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# Undefined Control Sequence: Giving Away Instant Solutions

Undefined control sequence error signifies different types of issues like writing confusing commands, forgetting to load a package, or loading a package at the wrong location, etc. You can say that this simple three-word error has more causes than you expect, but you don’t need to be worried about it because this post is here to serve you.

In this article, you’ll get to view the long list of well-explained causes and have a look at the solutions that’ll make your day. So, wait no more, grab a seat, and start reading to see how you can iron out the error.

## What Causes the Undefined Control Sequence Error?

The undefined control sequence – Overleaf error is caused by a command that is not recognized by LaTeX due to different reasons at the backend. Moreover, loading the same kind of obsolete and latest packages together or using pdftex to produce a document can result in the given error.

### – LaTeX is Unable To Identify the Command

Your code might be confusing LaTeX between the backslash that is part of a command and the backslash that is a part of the text. Also, it’s possible that you haven’t loaded the package required for using a particular command. In any of the said cases, you’ll receive the error under consideration today.

Think about it this way. You have entered some text that contains backslashes. In such a scenario, LaTex will consider the text following the backslash as a command and throw an undefined control sequence LaTeX table error.

Now, look at another example. You have entered the \includegraphics command without loading the graphicx package. Here, an undefined control sequence includegraphics error, will pop up to indicate that LaTeX can’t identify the command because the necessary package isn’t loaded.

### – You Are Using an Invalid Command Inside the Class

Not having clarity regarding classes and their commands can make you the victim of the above error. Putting it in simple words, if you use a command inside the wrong class, you’ll get to see the same error. It’s the same as using an irrelevant command inside a class.

For example, you write the \chapter command inside the article class. You must know that the \chapter command belongs to the book and report classes. Therefore, an undefined control sequence chapter error will interrupt your document processing.

### – You Have Loaded the Package After Starting the Document

It’s not only about loading the required package. Note that if you load the package after writing the \begin{document} command, neither the package will be recognized nor you’ll be able to use any of its commands. It means that the location where the package is loaded matters too.

Here is a relevant piece of code for your reference that’ll throw the undefined control sequence begin(document):

 \begin{document} \usepackage{graphicx}

### – You Are Loading the Subfig and Subfigure Packages in a Single File

Loading the subfig and subfigure packages in a single file is a possible reason behind the error stated in the title. You must know that both of the said packages offer the same functionality. Plus, the subfigure package has become obsolete, while the subfig has been used recently.

According to this, if you can find yourself loading both subfig and subfigure packages, then you should stop your search for the cause of the error.

### – The \RequirePackage[numbers]{natbib} Line Might Be the Reason

Although not necessarily always, sometimes, the line at which you require the natbib package can trigger the given error on your screen. So, if your code contains such a line, then you should consider this cause because it might be generating the error on your side.

Say that you have used the \RequirePackage command for multiple packages, including the natbib package. Suddenly, you receive an error saying undefined control sequence on your screen. In this case, requiring the natbib package can be the culprit.

### – Your Elsarticle Template Doesn’t Match the Elsarticle Class Version

If you are facing an undefined control sequence affiliation error while using the \affiliation command inside the elsarticle class, then the absence of the given command in the elsarticle version you are using currently can be the cause. Note that \affiliation isn’t found in elsarticle in TexLive19.

Furthermore, remember that the \affiliation command is available in the elsarticle version present in the fully updated TexLive20. So, even if you are working with TexLive20, but the elsarticle version is not the one present in fully updated TexLive20, then you’ll get the same error.

### – You Are Using pdftex To Produce Your Document

Using pdftex to produce your document can lead you to an undefined control sequence documentclass error. The commands, such as \usepackage, \begin{document}, etc., follow the LaTeX format and aren’t understandable by pdftex. Hence, the latter stops at the \begin{document}, and shows you an error.

This cause suggests that even if your entire LaTeX code is perfect, using the wrong program to compile the code, and produce a document can make things go wrong for you.

## How To Fix the Undefined Control Sequence Error?

You can fix the undefined control sequence error by replacing \ with \backslash in plain text, loading the package before starting the document, or writing only valid commands for the classes. Also, using latex or a relevant program to produce the document can solve the error.

### – Replace the \ in the Text With \backslash

The clearer your LaTeX code, the more chances you’ll have to satisfy LaTeX and stay away from the mentioned error. So, if you don’t intend to write a command after the backslash character, then it would be best to write \backslash instead of entering only the \ character.

This solution is the simplest one as all that you’ll have to do is to replace \ with \backslash in your already written text.

### – Study the Classes and Their Commands Well

Studying the classes and their commands well enough will help you make fewer mistakes while using commands. As you’ll be aware of everything already, you won’t mix and match irrelevant commands with different classes. Also, the error will have no reasons to stay.

Talking about the same example where you used the \chapter command inside the article class. Here, you’ll need to change either the class or the command. To stay with the \chapter command, you’ll have to switch from article to book or report. However, if you want to keep using the article class, you’ll need to tweak the command to make it \section or \subsection.

### – Load the Package, But Before Starting the Document

You should load the required package by using the \usepackage command to eliminate the given error. But don’t forget to load it before the \begin{document} to ensure that the error never comes back. Both of these steps will help LaTeX recognize the package and command.

Here is what the perfect sequence of commands looks like:

 \usepackage{graphicx} \begin{document}

### – Choose subfig Over subfigure

As the subfigure package has become obsolete, it would be better to choose the subfig package over the subfigure. Having only the subfig package will allow you to use the expected functionalities and kill the given error right away. So, it’s a no-loss deal.

It means if your code contains both packages, then removing the line that loads the subfigure package will resolve the issue.

### – Try Removing the Line That Requires the natbib Package

If you think your code might be facing the rarest problem where requiring the natbib package causes an error, then you might like to eliminate the erroneous line. However, removing the said line won’t allow you to use the commands belonging to the same package.

Please feel free to try out this solution to see if it kicks away the error.

### – Use the Elsarticle Template Matching the Current Elsarticle Version

You can resolve the error occurring while using the \affiliation command of the elsarticle class in TexLive19 by giving up using the \affiliation command. Next, you’ll need to follow the elsarticle template based on its version currently in use.

Making it simple, using only the commands available in your current elsarticle class version will solve the error.

### – Use Pdflatex, Latex, Xelatex, or Lualatex To Produce Your Document

You should use pdflatex, latex, xelatex, or lualatex program to efficiently produce a document from your LaTeX code. Moreover, choosing an appropriate program to produce the document will make the error leave your screen without causing any further problems. So, you shouldn’t hesitate to apply this solution.

Please feel free to go with any of the given programs because all of them understand LaTeX easily.

## Conclusion

As per this guide, the undefined control sequence error shows up whenever you go wrong with the commands, the packages, the classes, or the placement of backslashes. Although it’s difficult to predict the actual cause of the error on your side, the causes discussed above will make it easier for you to find out the culprit at the earliest. Please read on to view the listicle putting together some noteworthy points for you.

• It would be best to use \backslash instead of a \ character in the text.
• You should use the \ with only valid commands in a class and after loading the required package.
• Ensure to use \usepackage before \begin{document} to avoid the said error.
• Always use pdflatex and similar programs to generate the document.
• You should use subfig instead of subfigure to get rid of the error.

In the end, never forget that understanding the LaTeX format and having sufficient knowledge about its basics is the key to error-free document generation.


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How to derive the characteristic function of a polar coordinates representation of a bivariate normal

Suppose to have a bivariate normal variable $\mathbf{x}=(x_1,x_2)$ with mean $\mu$ and covariance matrix $\Sigma$. I move from $\mathbf{x}$ to $(\theta,r)$ where $x_1 = r \cos \theta$ and $x_2 = r \sin \theta$: the representation in polar coordinates of $\mathbf{x}$. My question is: is it possible to derive the characteristic function of $(\theta,r)$? and the characteristic function of $\theta$?

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IMR Press / RCM / Volume 23 / Issue 3 / DOI: 10.31083/j.rcm2303103
Open Access Review
Modern mapping and ablation of idiopathic outflow tract ventricular arrhythmias
Show Less
1 Arrhythmia Unit, Onassis Cardiac Surgery Center, 17674 Athens, Greece
2 Cardiac Arrhythmia Department, Humanitas Research Hospital IRCCS Rozzano, 20089 Milan, Italy
3 Department of Cardiology, KAT General Hospital of Attica, 14561 Athens, Greece
*Correspondence: stelios3n@msn.com (Stylianos Dragasis); k.letsas@gmail.com; letsas@ocsc.gr (Konstantinos P. Letsas)
Rev. Cardiovasc. Med. 2022, 23(3), 103; https://doi.org/10.31083/j.rcm2303103
Submitted: 27 November 2021 | Revised: 13 December 2021 | Accepted: 20 December 2021 | Published: 16 March 2022
(This article belongs to the Special Issue Catheter Ablation of Ventricular Tachycardia)
This is an open access article under the CC BY 4.0 license.
Abstract

Outflow tract (OT) premature ventricular complexes (PVCs) are being recognized as a common and often troubling, clinical electrocardiographic finding. The OT areas consist of the Right Ventricular Outflow Tract (RVOT), the Left Ventricular Outflow Tract (LVOT), the Aortomitral Continuity (AMC), the aortic cusps and the Left Ventricular (LV) summit. By definition, all OT PVCs will exhibit an inferior QRS axis, defined as positive net forces in leads II, III and aVF. Activation mapping using the contemporary 3D mapping systems followed by pace mapping is the cornerstone strategy of every ablation procedure in these patients. In this mini review we discuss in brief all the modern mapping and ablation modalities for successful elimination of OT PVCs, along with the potential advantages and disadvantages of each ablation technique.

Keywords
premature ventricular contractions
ablation
3D mapping systems
1. Introduction

Premature ventricular complexes (PVCs) are being recognized as a common and often troubling, clinical electrocardiographic finding. It is well known that a significant proportion of these arrhythmias usually originate from the outflow tract of either the right or the left ventricle (RVOT or LVOT). PVC-induced cardiomyopathy (PVC-CM), defined as the development of LV dysfunction caused by a high burden of PVCs (usually $\geq$10% of the total number of QRS complexes), has also been recognized as a clinical entity in consensus statements from both the European Heart Rhythm Society (EHRA) [1] and the American Heart Association (AHA) [2]. PVC treatment with catheter ablation is nowadays the proposed treatment for symptomatic patients suffering from PVC-CM [1, 2]. In this mini-review, we will describe some of the novel mapping and ablating modalities in idiopathic outflow tract (OT) PVCs. Basic anatomical considerations and relationships between OT structures, are reviewed and novel differentiation ECG algorithms are provided, in order to help with PVC localization. Moreover, we provide a thorough description of mapping techniques, catheters and contemporary 3-dimensional systems used and finally summarize on some of the most commonly used ablation techniques.

2. Basic anatomical considerations

In order to accurately pinpoint the location of an OT PVC with the use of the electrocardiogram (ECG), we must first obtain a comprehensive knowledge on the exact anatomic relation between the right and left OTs. The RVOT is located anteriorly to the LVOT, directed cephalad to the left shoulder, with the pulmonic valve located anteriorly and leftward, relative to the aortic valve. Conversely, the LVOT is situated posterior to the RVOT, with a cephalad direction to the right shoulder [3]. The aortic valve consists of three coronary cusps, the left coronary cusp, the right coronary cusp and the non-coronary cusp. The aortomitral continuity (AMC) is a fibrous band of tissue that extends between the anterior mitral leaflet and the left and non-coronary cusps of the aortic valve. The right coronary cusp (RCC) is located anteriorly, the non-coronary cusp (NCC) posteriorly and the left coronary cusp (LCC) posteriorly and to the left. A very important information is that the RCC is situated right posterior to the posteroseptal part of the RVOT, while the NCC is the lowest coronary cusp and in close proximity with the interatrial septum. The aortic cusps are frequent sites of successful ablation in OT PVCs [4]. Letsas et al. [4] recently reported a successful ablation rate of 46.7% in the aortic cusps, 4.9% in the AMC and 36.2% in the RVOT, for OT PVCs [4].

The left ventricular (LV) summit is the most superior epicardial segment of the LV and is defined as the triangular area formed by the left anterior descending (LAD) artery, the left circumflex artery (LCx) and the first septal perforator branch. The great cardiac vein (GCV) and its continuum, the anterior interventricular vein (AIV), transect and divide the LV summit into two parts (Fig. 1): (1) the inferior part, which is considered an “accessible area”, suitable for catheter ablation and (2) the superior part, also termed as the “unaccessible area” and unsuitable for catheter ablation, due to the presence of the epicardial arteries and epicardial fat [5, 6, 7].

Fig. 1.

Schematic representation of the LV summit and its relationship with the great cardiac vein (GCV) and the left anterior descending artery (LAD) in Left anterior oblique (LAO) view. L, Left coronary cusp; R, Right coronary cusp; NC, Non-coronary cusp.

3. How to pinpoint the origin of the PVC using the electrocardiogram

OT PVCs represent the majority of idiopathic PVCs. The OT areas consist of the RVOT, the LVOT, the AMC, the aortic cusps and the LV summit. By definition, all OT PVCs will exhibit an inferior QRS axis, defined as positive net forces in leads II, III and aVF. Several ECG differentiation algorithms have been published using stepwise approaches to pre-define the successful ablation area, guide initial vascular access (RVOT or LVOT/femoral vein or artery approach) and limit complications, given the close anatomical relationship between the RVOT and LVOT [8, 9, 10, 11, 12, 13, 14, 15]. The most likely origin of PVCs with left bundle branch block (LBBB) morphology in precordial lead V1 and precordial transition (first precordial lead with R$>$S in the PVC morphology) after lead V3 (leads V4–6) is the RVOT. Conversely, in cases where the precordial transition is located in lead V1 or V2, the most likely origin is the LVOT [8].

When the precordial transition in sinus rhythm precedes the precordial transition of the OT PVC (the PVC QRS exhibits later precordial transition than the QRS in sinus rhythm), the most likely origin is the RVOT [10]. For OT PVCs with precordial transition in lead V3, one of the easiest applicable algorithms is the V2S/V3R index [12]. It is calculated as the S-wave amplitude in lead V2 divided by the R-wave amplitude in lead V3 during the OT PVC. Values $\leq$1.5 predict LVOT origin with 89% sensitivity and 94% specificity. Recently, Efremidis et al. [15] published a novel differentiation algorithm for OT PVCs with precordial transition in V3, the RV1–V3 transition ratio, with higher sensitivity (94%) and less specificity (73%), using a cutoff value of $\geq$0.9 to predict LVOT origin. The most important published algorithms for differentiation of OT PVCs successful ablation location are summarized in Table 1 (Ref. [8, 9, 10, 11, 12, 13, 14, 15]).

Table 1.Common published ECG differentiation algorithms for successful localization of OT PVC origins.
 ECG FINDINGS DEFINITION RESULTS COMMENTS Transition in precordial leads [8] 1st precordial lead with R$>$S V1 or V2→LVOT origin Cardiac rotation affects reliability V4 and after→RVOT origin R wave duration index in leads V1 or V2 [9] Percentage of longer R wave duration in V1 or V2 to QRS complex duration R wave duration index $\geq$50% suggestive of a left-sided origin Discriminates RVOT vs aortic sinus cusp origins V2 transition ratio [10] Percentage of R wave during PVC (R/R+S)${}_{VT}$ in V2 divided by the percentage of R wave in sinus rhythm (R/R+S)${}_{SR}$ Values $\geq$0.6 predict left origin (91% accuracy) Used only if PVC precordial transition in lead V3 Transition Zone index (TZ index) [11] TZ score of PVC minus TZ score of sinus rhythm If TZ index $<$0, predictive of left sided origin with 88% sensitivity and 82% specificity V2S/V3R index [12] S wave in V2 divided by R wave amplitude in V3 during PVC Values $\leq$1.5 predict left sided origin with 89% sensitivity and 94% specificity It can be applied irrespective of precordial transition V4/V8 ratio [13] Ratio of PVC R wave in V4 to PVC R wave in V8 Values $>$3 suggestive of left sided origins with 88% sensitivity and 77% specificity V8 lead located at the inferior tip of the left scapula V4/V8 index [13] Ratio of PVC R wave V4/V8 divided by R wave V4/V8 in sinus rhythm Values $>$2.28 suggestive of left-sided origins with 67% sensitivity and 98% specificity V8 lead located at the inferior tip of the left scapula V3R/V7 index [14] R wave amplitude in lead V3R during PVC, divided by R wave amplitude in lead V7 during PVC V3R/V7 $\geq$0.85 predictive of LVOT origin with 87% sensitivity and 96% specificity V3R located at the right correspondent place of V3 and V7 at the left posterior axillary line at 5th intercostal space The RV1–V3 transition ratio [15] (RV1+RV2+RV3)${}_{PVC}$/(RV1+RV2+RV3)${}_{SR}$ Values $\geq$0.9 predict LVOT origin with 94% sensitivity and 73% specificity Only for OT PVCs with precordial transition in lead V3
4. Mapping the arrhythmia

Withdrawal of antiarrhythmic drugs for a period of at least 5 half-lives (preferably longer in cases of amiodarone) is of critical value prior to any ablation procedure for OT PVCs. Sedation is often avoided, because It may suppress the spontaneous PVC. However, mild sedation with intravenous propofol and fentanyl may be necessary. High density activation mapping using any of the contemporary 3-dimensional mapping systems (Carto 3 from Biosense Webster, Ensite NavX from St Jude Medical or Rhythmia from Boston Scientific) is the preferred modality, as it allows rapid, simultaneous and anatomically accurate acquisition of several activation points during the PVC, with the use of multipolar catheters with close coupled electrodes (Pentaray${}^{\textcopyright{}}$, HD Grid${}^{\textcopyright{}}$ and Orion${}^{\textcopyright{}}$ mapping catheters).

The Orion${}^{\textcopyright{}}$ catheter consists of 64 small sized electrodes, with a small interelectrode spacing of 2.5 mm, which provide faster simultaneous mapping with better near-field signal quality. This catheter combined with the Rhythmia${}^{\textcopyright{}}$ mapping system and Its automated intelligent annotation module, provides an accurate and very fast mapping of any PVC. However, due to its size and shape, its handling may be difficult in a small sized ventricle. The Pentaray${}^{\textcopyright{}}$ catheter consists of 20 electrodes distributed in 5 soft and flexible, 3-French branches. When combined with the novel Carto Prime${}^{\textcopyright{}}$ system mapping module, It can substantially improve ablation safety and efficacy, using features like Parallel mapping${}^{\textcopyright{}}$ (simultaneous 3D activation mapping of different morphology PVCs, from the same cardiac chamber) and LAT Hybrid${}^{\textcopyright{}}$ (providing an association of the PVC Local Activation Time information to Its corresponding normal sinus rhythm location). Finally the Ensite X${}^{\textcopyright{}}$ system from Abbott with Its AutoMap and TurboMap features, when combined with the Advisor HD Grid${}^{\textcopyright{}}$ catheter (16 electrodes), allows for fast and ultra high density mapping of any PVC, with the best signal to noise ratio. Fig. 2 exhibits a typical example of a 3D reconstruction model of both left and right ventricular heart chambers during activation mapping of a septal intramural PVC, using the Carto Prime module. Multipolar catheters are very useful in patients with high and even low PVC burdens, as they substantially accelerate the mapping procedure and limit the X-ray exposure for both the patient and operator.

Fig. 2.

3D reconstruction of the left and right ventricle using the Carto 3 mapping system during activation mapping of an intramural PVC which was successfully ablated in the basal septum from both the left and right ventricle (sequential ablation). Purple: Right Ventricle, Green: Left Ventricle, Yellow: Coronary Sinus, red and pink dots: ablation tags in the area with the earliest activation of the PVC.

However, these systems cannot entirely substitute person-reviewed electrogram analysis as an integral part of the mapping procedure. As all these systems are based on specific algorithms in order to time-reference the acquired intracardiac electrograms (EGMs) onto the 3D activation map, they are prone to error. In order for the 3D activation map of the PVC to be reliable, each activation point should ideally be reviewed carefully by the technician and the physician, in both the 3D module and the EP recording system. On the other hand, ultra high density maps acquired with catheters like Orion or Pentaray contain thousands of EGMs and manual review of each single EGM is practically impossible. The automatic QRS morphologic filtering algorithms incorporated in these systems might also exceed the physician’s ability to visually identify the mapped PVC. Finally, the EGM filter settings should be also set correctly (ideally 30–500 Hz for bipolar electrograms and 0.05–500 Hz for unipolar electrograms) in order to exclude any noise and maximize the quality of the recorded intracardiac signals.

After the initial 3D map has been acquired with a multipolar catheter, further mapping is advised with the ablation catheter, to accurately delineate the area of interest. Ideally, with adequate catheter-tissue contact (contact force of 5–10 grams), the ablation catheter should record a local bipolar EGM with a near field sharp component that precedes the QRS onset (pre-potential) by at least 20 msec and a synchronous unipolar EGM with a steep QS morphology (sharp downward slope), preferably with the presence of a notch [16, 17], especially in patients without previous extensive ablation [18]. The presence of a notched unipolar electrogram on the downstroke deflection has been reported to identify a distribution area of 0.8 $\pm$ 0.4 cm${}^{2}$ with an ablation success rate of 98.4% [17]. Unfortunately, the broadly used open-irrigated ablation catheters, due to their distal tip diameter of 3.5 mm and the 1 mm distance to their proximal bipole, seem to record a bipolar electrogram of a far greater underlying tissue area, with a diameter of 3.5 to 5.5 mm, depending on the angle of contact between catheter and tissue. Mini-electrode mapping improves mapping resolution (constructing “micro-bipolar” maps) and overcomes this obstacle especially in low voltage areas, therefore improving the ablation endpoint [19, 20]. Mapping and identification of very-low voltage areas in sinus rhythm (mean amplitude of 0.2 $\pm$ 0.1 mV) also seem to characterize the arrhythmogenic substrate in RVOT PVCs and may guide successful catheter ablation, when combined with pace mapping [21].

In patients with infrequent PVCs during 3D mapping despite aggressive stimulation protocols and intravenous isoprenaline (up to 40 $\mu{}$gr/min), pace mapping along with voltage mapping in sinus rhythm can be useful [21]. While previous reports have stressed that pace mapping is inferior to activation mapping, concerning the success of the ablation procedure [22], more contemporary data point out that pace mapping in patients with low intraprocedural burden of idiopathic OT PVCs can lead to comparable results regarding ablation efficacy, when it is executed under a certain protocol (ideally pace map correlation $>$90% with 2 mA pacing output, 2 msec pulse width and contact force $\geq$10 gr) [23]. In any case, pace mapping should always be attempted in combination with activation mapping (whenever it is possible), at the site of earliest ventricular activation. In RVOT PVCs, where initial ablation is ineffective, the pulmonary cusps, pulmonary artery and right coronary cusp should always be mapped afterwards [24, 25, 26]. The use of a long sheath (SR0 or SL1) to improve stability and maneuverability, along with pulmonary artery angiography may be useful to accurately determine the exact location of the ablation catheter [27].

5. The role of intracardiac echocardiography (ICE)

Intracardiac echocardiography has emerged as an effective tool in PVC ablation, as it can clearly help in the identification of the right ventricular inflow and outflow tract, the aorta, coronary ostia and the proximal course of the left main artery, obviating the need for coronary angiography, especially in cases with PVCs ablated from the left coronary cusp. As a result, it enables real time visualization of the ablation catheter stability in the aorta, limiting complications and radiation exposure [28, 29, 30]. Furthermore, steam pops, thrombus formation and pericardial effusion can be immediately identified and treated during the procedure, while ensuring the perpendicular catheter-tissue orientation, for optimal ablation results [31].

6. Ablation modalities

Irrigated ablation catheters have ultimately replaced the conventional, temperature-regulated, non-irrigated catheters, as they can create a more effective ablation lesion, avoiding the overheating phenomenon at the catheter-tissue interface. Irrigated catheters allow greater amounts of ablation energy to be delivered in the tissue, especially in areas with low blood flow, without any additional safety cost [32, 33, 34]. Ablation at a site with satisfactory near field prematurity in the bipolar EGM and steep negative (QS) unipolar EGM, as mentioned earlier, will usually suppress and cure the OT PVC. However, if the PVC origin is deeper (intramurally or epicardially, e.g., at the LV summit), endocardial catheter ablation is unlikely to suppress and cure the arrhythmia. In these cases, there are alternative ablative approaches, which will be discussed next.

If the activation mapping does not reveal any significant prematurity ($<$20 msec, far field local electrograms, absence of QS unipolar EGM at the earliest site, suboptimal pace maps, no or late suppression with immediate recurrence after ablation, equal activation times between septal RVOT and LVOT), that means that the PVC origin is deeper in the tissue that we are trying to ablate. Higher energy titration is the first step, but usually that is not enough. For septal (intramural) PVCs, if sequential unipolar ablation fails (ablation from the one side of the septum and on the exact opposite side, with the same catheter), simultaneous unipolar ablation may be effective in patients with septal PVCs refractory to sequential ablation [35, 36]. Simultaneous unipolar ablation is performed with two separate irrigated catheters each one connected to a separate energy generator with separate ground pads and positioned opposite to each other. This type of ablation results in deeper and larger lesions than unipolar sequential ablation [37].

Bipolar ablation is another ablation modality, where 2 ablation catheters are used, where one of them is responsible for the energy delivery and the other acts as a ground pad, connected to the indifferent electrode port. Consequently, the intervening myocardium is subjected to higher current density between the two catheter tips, which results to deeper and more concentrated lesions that simultaneous unipolar ablation (transmural lesions 20–25 mm) [38, 39]. The optimal distance between the two catheters should be 15–20 mm. The delivered energy is uniform between the two catheters, in contrast to unipolar simultaneous ablation, where the energy is titrated separately for each catheter. Major drawback is that there is no widely available setting for this setup and that there is no consensus regarding the optimal energy delivery and duration. Fig. 3 depicts catheter positioning in a patient subjected to bipolar ablation for a septal intramural PVC in our lab.

Fig. 3.

Right anterior oblique fluoroscopic image of bipolar ablation of a septal PVC in our lab. Irrgated catheter positioned on the septal side of the right ventricle and a 4 mm non-irrigated catheter acting as the indifferent electrode via the septal side of the left ventricle (retrograde aortic approach).

Ablation in distant areas, such as the LV summit can also be performed endocardially, with the use of half normal saline as the irrigant. Half normal saline acts as an insulator to the radiofrequency current, resulting in more tissue energy delivery, when compared with normal saline and larger ablation lesions [40]. Dextrose water as an irrigant produces even larger lesions and increased steam pops in comparison with half saline [40]. Both half saline and dextrose irrigation produces larger ablation lesions, at the expense of increased steam pops especially with catheter forces that exceed 20 gr.

Energy delivery to OT PVCs originating from the LV summit or septal RVOT (via septal collaterals) can also be performed via a novel technique using a guidewire [41]. The 0.014-inch Vision guidewire is advanced into the anterior interventricular vein via an Inquiry Luma-Cath. Since the wire unipolar recording exhibits greater prematurity than the other sites, radiofrequency ablation can be applied through its body (titrated up to 20W) using the Smartablate generator (Biosense Webster) and with its proximal end in a saline bath. Coronary angiography is mandatory before energy delivery, in order to delineate coronary artery anatomy. Fig. 4 (Ref. [41]) depicts the wire position and recordings in a female patient suffering from OT PVCs, who was referred for catheter ablation to our electrophysiology lab.

Fig. 4.

LV summit PVC ablation technique via an insulated guidewire (Vision© guidewire). (a) 12-lead ECG showing the OT PVC. (b) 3D activation mapping of the RVOT, coronary venous system and left aortic cusp. (c) unipolar recording via the 0.014-inch guidewire with the earliest signal in the anterior interventricular vein (AIV). (d) LAO view showing the wire course at the proximal AIV. (e) PVC abolition with RF energy delivery up to 20W. RVOT, Right Ventricular Outflow Tract; GCV, Great Cardiac Vein; LCC, left coronary cusp. Reproduced with permission from Efremidis et al. [41].

Other novel techniques for intramyocardial PVCs include catheter ablation via a specially designed 27-G needle tip, which except of energy delivery, it can also pace and record intracardiac electrograms [42]. Energy delivery is greatly augmented via saline irrigation through the needle [43]. Temperature controlled radiofrequency energy is limited to 60 ${}^{\circ}$C for 1–2 minutes. Intracoronary ethanol injection using an over-the-wire angioplasty balloon has been repeatedly performed for PVCs refractory to radiofrequency ablation, despite the risk of possible collateral damage after ethanol leak and backflow [44, 45]. Mapping of septal branches of the anterior interventricular vein (AIV) via a miniaturized multielectrode catheter or via an angioplasty wire, is always performed beforehand. Finally, epicardial ablation is also an alternative for LV summit PVCs.

7. Conclusions

The ventricular outflow tracts represent common ablation sites for idiopathic premature ventricular contractions and radiofrequency catheter ablation is an effective therapeutic strategy for these patients. Comprehensive knowledge of the ECG characteristics of OT PVCs and the exact anatomic relations between the LVOT and RVOT are of essential value in order to successfully treat these arrhythmias. Whenever standard ablation techniques prove ineffective, different strategies can be utilized to improve the procedural success rates.

Abbreviations

AHA, American Heart Association; AIV, Anterior Interventricular Vein; AMC, Aortomitral Continuity; CM, Cardiomyopathy; ECG, Electrocardiogram; EHRA, European Heart Rhythm Society; GCV, Great Cardiac Vein; LAD, Left Anterior Descending Artery; LBBB, Left Bundle Branch Block; LCC, Left Coronary Cusp; LCx, Left Circumflex Artery; LV, Left Ventricular; LVOT, Left Ventricular Outflow Tract; NCC, Non Coronary Cusp; OT, Outflow tract; PVC, Premature Ventricular Complex; PVCs, Premature Ventricular Complexes; RCC, Right Coronary Cusp; RVOT, Right Ventricular Outflow Tract.

Author contributions

SD—was the main author of this article. KV and AF—provided the images and tables. PM, AS, AZ, MEZ and MK—performed the online article search and provided the reference pool. NK, KPL and ME—conceived and designed the article layout.

Ethics approval and consent to participate

Not applicable.

Acknowledgment

Not applicable.

Funding

This research received no external funding.

Conflict of interest

The authors declare no conflict of interest. Konstantinos P. Letsas and Konstantinos Vlachos are serving as the Guest editors of this journal. We declare that Konstantinos P. Letsas and Konstantinos Vlachos had no involvement in the peer review of this article and has no access to information regarding its peer review. Full responsibility for the editorial process for this article was delegated to Bernard Belhassen and Petr Ostadal.

Publisher’s Note: IMR Press stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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text:
# Benchmarks or generic configurations for optimal flow control

I am about to test my algorithms for solving optimal control problems of type:

Find an input $u$, such that for a time interval $(0,T]$ the cost functional $$J(v,u) = \mathcal M(v(T)) + \int_0^T\mathcal K(v(t),u(t)) dt,$$ becomes minimal, where $v$ is the velocity of flow modelled by the incompressible Navier-Stokes equations. The functionals $\mathcal M$ and $\mathcal K$ measure the state trajectory, e.g. in terms of how well a given target flow is approximated.

For 2D, typical test problems I have seen comprise the backward facing step, driven cavity (as in the pics below) or the cylinder wake. However, I haven't found discussions on

What is a good configuration, or even a benchmark, for testing numerical solution approaches to optimal flow control?

I want to do my first tests on a very basic level. That's why I think the setup should be

• reasonably sized (~$10^5$ DOFs),
• laminar,
• and for distributed control.

Here, distributed means that the control appears in the right hand side of the Navier-Stokes equations and not in the boundary conditions.


text:
# Slash the matrix

You are given a matrix of forward and back slashes, for instance:

//\\
\//\
//\/

A slash cuts along the diagonal of its cell corner-to-corner, splitting it in two pieces. Pieces from adjacent (horizontally or vertically) cells are glued together. Your task is to count the number of resulting pieces. For the same example, the pieces are easier to see in this illustration - 8 of them:

Write a function or a complete program. Input is a non-empty matrix in any convenient form. You may choose any pair of values (characters or numbers) to represent / and \; in the tests below we use 0=/ and 1=\. Loopholes forbidden. Shortest wins.

in:
[[0,0,1,1],
[1,0,0,1],
[0,0,1,0]]
out:
8

in:
[[1]]
out:
2

in:
[[1,0],
[1,1],
[0,1],
[0,0]]
out:
6

in:
[[1,0,1,1,0,1,0,0,0,1,1,1],
[1,0,1,0,1,1,1,1,1,1,1,0],
[1,1,1,0,1,1,0,1,1,1,1,0],
[0,1,0,1,0,1,0,0,1,0,1,1],
[1,1,1,1,0,0,1,1,1,0,0,1]]
out:
19

in:
[[1,0,1,1,0,1,0,0,0,1,1,1,1,0,1,0,1],
[1,1,1,1,1,1,0,1,1,1,0,1,1,0,1,1,1],
[1,0,0,1,0,1,0,1,0,0,1,0,1,1,1,1,1],
[1,0,0,1,1,1,0,0,1,0,0,1,0,1,1,1,1],
[0,1,0,0,0,0,1,0,1,0,0,1,0,1,1,1,1],
[0,1,0,0,1,0,0,0,1,0,1,0,0,1,1,1,0],
[0,1,1,1,1,1,0,0,1,0,1,0,0,1,1,1,0]]
out:
27

in:
[[0,1,1,1,1,1,1,1,0,0,1,0,1,0,0,0,0],
[1,1,1,0,0,0,1,1,1,1,1,0,1,1,0,1,0],
[1,0,0,1,1,1,0,0,0,1,0,1,0,0,1,1,1],
[0,0,0,1,1,0,1,0,0,0,1,1,0,1,1,1,0],
[1,1,0,1,0,0,1,0,0,1,0,1,0,0,0,1,0],
[0,1,0,1,0,0,0,1,0,1,0,1,0,1,1,0,0],
[0,1,1,1,0,0,1,0,1,0,0,0,0,1,1,1,1]]
out:
32

# MATL, 21 bytes

3XytPJ*-X*Xj~4&1ZIunq

The input is a matrix with 1 for \ and j (imaginary unit) for /.

With some extra code, you can see the different pieces in random colours. Or increase the resolution for a better looking result.

## Explanation

Consider input [1,j; 1,1; j,1; j,j] as an example. This corresponds to

\/
\\
/\
//

3Xy creates a 3×3 identity matrix:

1 0 0
0 1 0
0 0 1

tP pushes a copy of this matrix and flips it vertically. J* multiplies each entry by the imaginary unit, to give

0 0 j
0 j 0
j 0 0

- subtracts the two matrices:

 1     0    -j
0   1-j     0
-j    0     1

X* takes the input matrix implicitly and computes the Kronecker product. This replaces each entry in the input matrix by its product with the above 3×3 matrix:

 1    0   -j    j    0    1
0  1-j    0    0  1+j    0
-j    0    1    1    0    j
1    0   -j    1    0   -j
0  1-j    0    0  1-j    0
-j    0    1   -j    0    1
j    0    1    1    0   -j
0  1+j    0    0  1-j    0
1    0    j   -j    0    1
j    0    1    j    0    1
0  1+j    0    0  1+j    0
1    0    j    1    0    j

Xj takes the real part:

1 0 0 0 0 1
0 1 0 0 1 0
0 0 1 1 0 0
1 0 0 1 0 0
0 1 0 0 1 0
0 0 1 0 0 1
0 0 1 1 0 0
0 1 0 0 1 0
1 0 0 0 0 1
0 0 1 0 0 1
0 1 0 0 1 0
1 0 0 1 0 0

Note how the above matrix is a "pixelated" version of

\/
\\
/\
//

~ applies logical negation, that is, swaps 0 and 1:

0 1 1 1 1 0
1 0 1 1 0 1
1 1 0 0 1 1
0 1 1 0 1 1
1 0 1 1 0 1
1 1 0 1 1 0
1 1 0 0 1 1
1 0 1 1 0 1
0 1 1 1 1 0
1 1 0 1 1 0
1 0 1 1 0 1
0 1 1 0 1 1

4&1ZI specifies 4-connectivity, and finds connected components considering 1 as foreground and 0 as background. The result is a matrix of labelled connected components, where each original 1 is replaced by an integer label:

0 3 3 3 3 0
1 0 3 3 0 5
1 1 0 0 5 5
0 1 1 0 5 5
2 0 1 1 0 5
2 2 0 1 1 0
2 2 0 0 1 1
2 0 4 4 0 1
0 4 4 4 4 0
4 4 0 4 4 0
4 0 4 4 0 6
0 4 4 0 6 6

unq computes the number of unique elements and subtracts 1. This gives the number of components, which is implicitly displayed.

• would it help if you chose [1,0,0; 0,1,0; 0,0,1] and [0,0,j; 0,j,0; j,0,0] as the two values for \ and /?
– ngn
Oct 28, 2019 at 19:46
• The essential idea of resizing the slashes so that connected components work naturally is fantastic. Oct 28, 2019 at 20:07
• @ngn I assumed that wasn't allowed. Yes, it would help, but allowing that would make the challenge less interesting in my opinion. (Also my answer would be less interesting, as Jonah's eloquent comment illustrates). By that rule, using [1,0,0; 0,1,0; 0,0,1] and [0,0,1; 0,1,0; 1,0,0] would probably be valid too?, and then the challenge would just be "find connected components", which is less interesting and possibly a dupe. So my recommendation, if I may say so, is to require two different characters or numbers as inputs. That's how I understood "Given a matrix of forward and back slashes" Oct 28, 2019 at 21:00
• @LuisMendo tbh, when i designed the challenge i didn't anticipate that reduction to connected components could be done so easily - that's the beauty of your solution. i'll amend it as you recommend.
– ngn
Oct 28, 2019 at 21:06

# MSX-BASIC, 226 199 bytes

1SCREEN2:READC,L:W=256/C:H=192/L:FORJ=1TOL:FORI=1TOC:A=H:B=H:READD:IFDTHENA=0:B=-H
2LINE(I*W,J*H-A)-STEP(-W,B):NEXTI,J:FORY=0TO191:FORX=0TO255:IFPOINT(X,Y)=4THENR=R+1:PAINT(X,Y)
3NEXTX,Y:SCREEN0:?R

This script draw slashes on a whole screen and use PAINT operator to count closed areas.

To test:

• copy to clipboard the script with test cases data (see below)
• open online emulator https://webmsx.org/
• press Alt-V and Ctrl+V to past test script into MSX
• press Enter and F5 to run test script
• wait a some time to see a result (press Shift-Alt-T to switch in CPU Turbo 8X mode to save your time)
1SCREEN2:READC,L:W=256/C:H=192/L:FORJ=1TOL:FORI=1TOC:A=H:B=H:READD:IFDTHENA=0:B=-H
2LINE(I*W,J*H-A)-STEP(-W,B):NEXTI,J:FORY=0TO191:FORX=0TO255:IFPOINT(X,Y)=4THENR=R+1:PAINT(X,Y)
3NEXTX,Y:SCREEN0:?R
10 ' this and below lines are not counted
20 ' the script runs first uncommented test case.
30 ' comment unnecessary test cases
100 '
110 'test case 1: expected output=8
120 'DATA 4,3
130 'DATA 0,0,1,1,1,0,0,1,0,0,1,0
200 '
210 'test case 2: expected output=2
220 'DATA 1,1
230 'DATA 1
300 '
310 'test case 3: expected output=6
320 'DATA 2,4
330 'DATA 1,0,1,1,0,1,0,0
400 '
410 'test case 4: expected output=19
420 'DATA 12,5
430 'DATA 1,0,1,1,0,1,0,0,0,1,1,1
440 'DATA 1,0,1,0,1,1,1,1,1,1,1,0
450 'DATA 1,1,1,0,1,1,0,1,1,1,1,0
460 'DATA 0,1,0,1,0,1,0,0,1,0,1,1
470 'DATA 1,1,1,1,0,0,1,1,1,0,0,1
500 '
510 'test case 5: expected output=27
520 DATA 17,7
530 DATA 1,0,1,1,0,1,0,0,0,1,1,1,1,0,1,0,1
540 DATA 1,1,1,1,1,1,0,1,1,1,0,1,1,0,1,1,1
550 DATA 1,0,0,1,0,1,0,1,0,0,1,0,1,1,1,1,1
560 DATA 1,0,0,1,1,1,0,0,1,0,0,1,0,1,1,1,1
570 DATA 0,1,0,0,0,0,1,0,1,0,0,1,0,1,1,1,1
580 DATA 0,1,0,0,1,0,0,0,1,0,1,0,0,1,1,1,0
590 DATA 0,1,1,1,1,1,0,0,1,0,1,0,0,1,1,1,0
600 '
610 'test case 5: expected output=32
620 DATA 17, 7
630 DATA 0,1,1,1,1,1,1,1,0,0,1,0,1,0,0,0,0
640 DATA 1,1,1,0,0,0,1,1,1,1,1,0,1,1,0,1,0
650 DATA 1,0,0,1,1,1,0,0,0,1,0,1,0,0,1,1,1
660 DATA 0,0,0,1,1,0,1,0,0,0,1,1,0,1,1,1,0
670 DATA 1,1,0,1,0,0,1,0,0,1,0,1,0,0,0,1,0
680 DATA 0,1,0,1,0,0,0,1,0,1,0,1,0,1,1,0,0
690 DATA 0,1,1,1,0,0,1,0,1,0,0,0,0,1,1,1,1

• Wait a second... this isn't powershell Nov 1, 2019 at 18:32
• oops! ¯\_(ツ)_/¯ Nov 1, 2019 at 18:36

# JavaScript (ES6),  175  174 bytes

This is probably overcomplicated.

a=>a.map((r,y)=>r.map((v,x)=>[2,4].map(s=>v&s||(n++,g=(x,y,s,i,v=(r=a[y])&&r[x])=>!(v&(s^=i%2==v%2&&6))/v&&g(x+1-(r[x]|=s,s&2),y++,s^6)|g(x,y-=v%2*2^s&2,s,v))(x,y,s))),n=0)|n

Try it online!

# Charcoal, 70 bytes

≔×³Ｌθη≔×³Ｌ§θ⁰ζＢζηψＦＬθ«Ｊ¹⊕×³ιＦ§θι«¿κＰ\²Ｐ/²Ｍ³→»»Ｆη«Ｊ⁰ιＦζ«⊞υ¬℅ＫＫ¤#→»»⎚ＩΣυ

Try it online! Link is to verbose version of code. Uses the same format as the examples (except Charcoal requires the list of inputs as an outer array). Explanation:

≔×³Ｌθη≔×³Ｌ§θ⁰ζ

Like @LuisMendo, we're going to be drawing the matrix at 3x scale, so calculate that in advance.

Ｂζηψ

Draw an empty rectangle of that size so that we can fill the edge pieces.

ＦＬθ«Ｊ¹⊕×³ιＦ§θι«

Loop over the rows and columns.

¿κＰ\²Ｐ/²Ｍ³→»»

Draw each slash at triple size and move to the next one.

Ｆη«Ｊ⁰ιＦζ«

Loop over all of the squares.

⊞υ¬℅ＫＫ

Record whether this square was empty.

¤#→»»

But try filling it anyway before moving on to the next square. (Fill does nothing if the current square is not empty.)

⎚ＩΣυ

Clear the canvas and output the total number of empty squares found, which equals the number of pieces (because each piece would have been immediately filled in as soon as we counted it).

# C# (Visual C# Interactive Compiler), 292 bytes

n=>{var x=n.SelectMany(l=>"\0".Select(g=>l.SelectMany(r=>r.Skip(g).Concat(r.Take(g))).ToList())).ToList();int i=0,j=0,t=0;for(;i<x.Count;i++)for(j=0;j<x[0].Count;k(i,j++))t+=x[i][j]%2;void k(int a,int b){try{if(x[a][b]<50){x[a][b]='2';k(a+1,b);k(a-1,b);k(a,b-1);k(a,b+1);}}catch{}}return t;}

The \0 should be a literal null byte.

112 for /, 211 for \

Try it online!

# Jelly, 50 46 bytes

®_ż+¥"SƝż€"Jż‘ḞṖ
ZJḤ©Żż‘$;€þJ;ÇẎfƇ@Ẏ¥€Q$ÐLL

Try it online!

A full program taking a matrix as its input with -0.5 as / and 0.5 as \`. Returns an integer with the number of pieces.

Full explanation to follow, but works by generating a list of all the pairs of connected cells, and then merging overlapping sets until there’s no change. The final number of sets is the desired answer.


text:
# XML Backup is Smaller in Size

#### お困りですか?

アトラシアン コミュニティをご利用ください。

コミュニティに質問

[Unable to render {include} The included page could not be found. ({include} をレンダリングできません。ページが見つかりませんでした)] を選択し、

## 症状

In Confluence the data appeared to be intact. However the XML backup appeared smaller than older backups. There are no error messages related to the backup in the log file.

## 原因

It appears that the reason why the backup is smaller is due to a compression algorithm behaviour.

Uncompressed, the XML backup will be bigger than older backups. When you zip up both of the entities.xml files separately, you would find that the current backup's entities.xml zip result is smaller.

## ソリューション

Your backup is not corrupted and you can proceed as per usual with your backup.

この内容はお役に立ちましたか?

はい
いいえ
この記事についてのフィードバックを送信する


text:
# How do I use elimination to find the solution of the system of equations y=1/3x+7/3 and y=−5/4x+11/4?

Jul 9, 2015

You multiply each equation by the LCM of the denominators and then solve by elimination as usual.

#### Explanation:

(1) $y = \frac{1}{3} x + \frac{7}{3}$
(2) $y = - \frac{5}{4} x + \frac{11}{4}$

Step 1: Multiply each equation by the least common multiple (LCM) of the denominator.

Multiply Equation 1 by $3$ and Equation 2 by $4$.

(3) $3 y = x + 7$
(4) $4 y = - 5 x + 11$

Step 2: To solve by elimination, multiply Equation 3 by $5$.

(5) $15 y = 5 x + 35$
(4) $4 y = - 5 x + 11$

Step 3: Add the two equations.

$19 y = 46$

(6) $y = \frac{46}{19}$

Step 4: Substitute Equation 6 into Equation 3.

x+7 = 3y = 3×46/19 = 138/19

$x = \frac{138}{19} - 7 = \frac{138 - 133}{19} = \frac{5}{19}$

The solution is $x = \frac{5}{19}$, $y = \frac{46}{19}$

Check:

Substitute in Equation 1.

$y = \frac{1}{3} x + \frac{7}{3}$

46/19 = 1/3× 5/19 + 7/3 = 5/57 + 7/3 = 5/57 + 133/57 =138/57 =46/19

Substitute in Equation 2.

$y = - \frac{5}{4} x + \frac{11}{4}$

46/19 = -5/4× 5/19 + 11/4 = -25/76 + 11/4 = -25/76 + 209/76 = 184/76 = 46/19


text:
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1.11

# Installation of Scalismo Lab

Welcome to Scalismo Lab! In this environment simple Scalismo programming can be done, with no Integrated Development Environment (IDE) required.

This document will guide you through the installation procedure.

Scalismo Lab is available as an executable Java jar (with a dataset), and is downloadable here.

Note: it is possible that the version of Scalismo we used for this course differs a little bit from the latest version you will be using.

### How to install and run Scalismo Lab:

Once the zip is downloaded and unzipped, all that is required to run the tool is a Java 8 Runtime Environment.

In case you want to use OpenJDK 8 on Linux, please make sure that the OpenJFX package is also installed on your system.

To run the tool on Windows and Mac:

2. Double-click on the scalismoLab.jar file.

On Linux and as an alternative on Windows and Mac, you can also run it in a console (terminal or windows command window):

cd path_to_unzipped_directory
java -jar scalismoLab.jar

That’s it !

You should then have a setting with three windows similar to the screenshot below:

Figure 1: screenshot Scalismo Lab

Note that in case you are handling large data files, you might want to increase the amount of memory pre-allocated for the tool, as follows:

java -Xmx3g -jar scalismoLab.jar

Also, we recommend to restart the program for each exercise to avoid crashes.

That’s it. You are now all set.

If you want to, you can now switch to Scalismo Lab and go through the Readme document that will give you more details on the usage of Scalismo Lab. This can be found in the Menu bar -> Documents -> Readme


text:
Definitions

# Convolution sampling

In mathematics, convolution sampling is a technique used to generate observations from a distribution.

A number of distributions can be expressed in terms of the (possibly weighted) sum of two or more random variables from other distributions (The distribution of the sum is the convolution of the distributions of the individual random variables).

## Example

Consider the random variable $X sim Erlang\left(k, theta\right)$, defined as the sum of k random variables each with distribution $exp\left(k theta\right)$.

Notice that:

$E\left[X\right] = frac\left\{1\right\}\left\{k theta\right\} + frac\left\{1\right\}\left\{k theta\right\} + ... + frac\left\{1\right\}\left\{k theta\right\} = frac\left\{1\right\}\left\{theta\right\}$

One can now generate $Erlang\left(k, theta\right)$ samples using the sampler for the exponential distribution:

if $X_i sim exp\left(k theta\right)$ then $X=sum_\left\{i=1\right\}^k X_i sim Erlang\left(k,theta\right)$

Search another word or see Convolution samplingon Dictionary | Thesaurus |Spanish


text:
# Problem Trying to get PORTB LED's to blink PIC16F887 - HELP PLEASE SAVE MY SANITY

Status
Not open for further replies.

#### 3BABY

##### Member level 5
Hi Guys,

i have googled and searched but the 16F887 seems to be harder to get working then a 18F4550.. can someone please point out the obvious mistake im making in the below? im only working with the 16F887 as i have run out of 18F4550's... any help would save my sanity greatly!!!!

Code:
;**************************************************************************************************
;
;	Target: PIC16F887
;	Oscillator: 8Mhz
;
;
;**************************************************************************************************

LIST	p=16F887		;tell assembler what chip we are using
#include<p16f887.inc>

__config 0x1D19			;sets the configuration settings (oscillator type etc.)

;-------- Register Definitions------

W       	EQU   H'0000'
F   		EQU   H'0001'

;-------- Register Files----

d10			EQU 	0x50
d11			EQU 	0x51
d12			EQU 	0x52
d13			EQU 	0x53

;------------ Port Settings --------------------------------------

ORG	0

;------------ Port Settings --------------------------------------

BSF			STATUS,5       	;Switch to Bank 1

CLRF PORTB			;PORTB is output
MOVLW b'00000000'
MOVWF TRISB

bcf      	STATUS,5       	;Switch back to Bank 0

;------------------------------------ MAIN PROGRAM ------------------------------------------------------------------

START

CLRF PORTB

MAIN

MOVLW b'11111111'
MOVWF PORTB

CALL DELAY_10SECS
NOP

MOVLW b'00000000'
MOVWF PORTB

CALL DELAY_10SECS
NOP

GOTO MAIN

;------ DELAY_10SECS - 10 Seccond delay --------------------------------------------------------------------------------------------

DELAY_10SECS

; Delay = 10 seconds
; Clock frequency = 8 MHz

; Actual delay = 10 seconds = 20000000 cycles
; Error = 0 %

;	cblock
;	d10
;	d11
;	d12
;	endc

;19999992 cycles
movlw	0xB5
movwf	d10
movlw	0x99
movwf	d11
movlw	0x2C
movwf	d12
Delay_10_1
decfsz	d10, f
;	goto	$+2 goto D10_2 decfsz d11, f D10_2 goto D10_3 decfsz d12, f D10_3 goto Delay_10_1 ;4 cycles ;goto$+1
;goto	$+1 NOP NOP NOP ;4 cycles (including call) return ;---------------------------------------------------------------------------------------------------------------------------------------- END #### hexreader ##### Advanced Member level 2 You really should go through the Gooligum PIC tutorials to learn better programming style. Here is your code with minimum fix, just enough to make it operate: Code: ;************************************************************************************************** ; ; Target: PIC16F887 ; Oscillator: 8Mhz ; ; ;************************************************************************************************** LIST p=16F887 ;tell assembler what chip we are using #include <p16F887.inc> ; config 0x1D19 ;sets the configuration settings (oscillator type etc.) __CONFIG _CONFIG1, _LVP_OFF & _FCMEN_OFF & _IESO_OFF & _BOR_OFF & _CPD_OFF & _CP_OFF & _MCLRE_ON & _PWRTE_ON & _WDT_OFF & _HS_OSC __CONFIG _CONFIG2, _WRT_OFF & _BOR21V cblock 0x20 d10 d11 d12 d13 endc ORG 0 ;------------ Port Settings -------------------------------------- CLRF PORTB ;PORTB is all zeros BSF STATUS,5 ;Switch to Bank 1 MOVLW b'00000000' MOVWF TRISB bcf STATUS,5 ;Switch back to Bank 0 ;------------------------------------ MAIN PROGRAM ------------------------------------------------------------------ START CLRF PORTB MAIN MOVLW b'11111111' MOVWF PORTB CALL DELAY_10SECS NOP MOVLW b'00000000' MOVWF PORTB CALL DELAY_10SECS NOP GOTO MAIN ;------ DELAY_10SECS - 10 Seccond delay -------------------------------------------------------------------------------------------- DELAY_10SECS ; Delay = 10 seconds ; Clock frequency = 8 MHz ; Actual delay = 10 seconds = 20000000 cycles ; Error = 0 % ; cblock ; d10 ; d11 ; d12 ; endc ;19999992 cycles movlw 0xB5 movwf d10 movlw 0x99 movwf d11 movlw 0x2C movwf d12 Delay_10_1 decfsz d10, f ; goto$+2
goto	D10_2
decfsz	d11, f
D10_2
goto	D10_3
decfsz	d12, f
D10_3
goto	Delay_10_1

;4 cycles
;goto	$+1 ;goto$+1

NOP
NOP
NOP

;4 cycles (including call)
return

;----------------------------------------------------------------------------------------------------------------------------------------

END

3BABY

### 3BABY

Points: 2

#### 3BABY

##### Member level 5
You really should go through the Gooligum PIC tutorials to learn better programming style.

Here is your code with minimum fix, just enough to make it operate:

Code:

Thankyou, ill have a look through Gooligum, i had used the same config code trying to get it working the first time but always got these (see pic) errors.. and now when i try re-complie the code you provided im getting the same error (see pic).. any idea why?

obviously you cant remove the "," or you would get a missing operator..

---------- Post added at 12:10 ---------- Previous post was at 11:46 ----------

ok so.. it looks like that config was for more like the 87X? i have looked around and found the below for the 887

CONFIG1 = _LVP_OFF & _FCMEN_OFF & _IESO_OFF & _BOR_OFF & _CPD_OFF & _CP_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT
CONFIG2 = _WRT_OFF & _BOR21V

it compiles but doesnt and programs but doesn't actually run..

Your version of config setting works fine for me, as below, and on real hardware, all PORTB LEDs flash on for 10 seconds, then off, repeatedly.

Maybe you have a hardware problem

Code:
;**************************************************************************************************
;
;	Target: PIC16F887
;	Oscillator: 8Mhz
;
;
;**************************************************************************************************

LIST	 p=16F887		;tell assembler what chip we are using
#include <p16F887.inc>

;	__CONFIG    _CONFIG1, _LVP_OFF & _FCMEN_OFF & _IESO_OFF & _BOR_OFF & _CPD_OFF & _CP_OFF & _MCLRE_ON & _PWRTE_ON & _WDT_OFF & _HS_OSC
;	__CONFIG    _CONFIG2, _WRT_OFF & _BOR21V

CONFIG1 = _LVP_OFF & _FCMEN_OFF & _IESO_OFF & _BOR_OFF & _CPD_OFF & _CP_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT
CONFIG2 = _WRT_OFF & _BOR21V

cblock 0x20

d10
d11
d12
d13
endc

ORG	0

;------------ Port Settings --------------------------------------

CLRF    PORTB			;PORTB is all zeros
BSF     STATUS,5       	;Switch to Bank 1

MOVLW b'00000000'
MOVWF TRISB

bcf      	STATUS,5       	;Switch back to Bank 0

;------------------------------------ MAIN PROGRAM ------------------------------------------------------------------

START

CLRF PORTB

MAIN

MOVLW b'11111111'
MOVWF PORTB

CALL DELAY_10SECS
NOP

MOVLW b'00000000'
MOVWF PORTB

CALL DELAY_10SECS
NOP

GOTO MAIN

;------ DELAY_10SECS - 10 Seccond delay --------------------------------------------------------------------------------------------

DELAY_10SECS

; Delay = 10 seconds
; Clock frequency = 8 MHz

; Actual delay = 10 seconds = 20000000 cycles
; Error = 0 %

;	cblock
;	d10
;	d11
;	d12
;	endc

;19999992 cycles
movlw	0xB5
movwf	d10
movlw	0x99
movwf	d11
movlw	0x2C
movwf	d12
Delay_10_1
decfsz	d10, f
;	goto	$+2 goto D10_2 decfsz d11, f D10_2 goto D10_3 decfsz d12, f D10_3 goto Delay_10_1 ;4 cycles ;goto$+1
;goto	\$+1

NOP
NOP
NOP

;4 cycles (including call)
return

;----------------------------------------------------------------------------------------------------------------------------------------

END

#### betwixt

##### Super Moderator
Staff member
Observations:

You can save yourself a lot of grief by using 'banksel' instead of switching banks by changing bits in the STATUS register. See the help file for instructions.

You will have trouble if you try to use interrupts. Nothing is wrong with your code but if an interrupt occurred it would almost certainly crash the program. I'm assuming you are using MPLAB as the assembler so I suggest you start all your programs by copying the template Microchip provide into the edit window before adding your own code. It will give you the 'bare bones' of a program which you can then expand and it will include all the essential configuration information and an interrupt handler which you can use if needed. In a normal instalation and for absolute code the templates are saved in:

C:\Program Files\Microchip\MPASM Suite\Template\Code

Brian.

3BABY

### 3BABY

Points: 2

#### 3BABY

##### Member level 5
Observations:

You can save yourself a lot of grief by using 'banksel' instead of.............

Thanks betwixt.. i have had a look at those templates.. ill use them in future. i have to educate myself on bank selecting as in still abit fuzzy on what it does.

Your version of config setting works fine for me, as below, and on real hardware, all PORTB LEDs flash on for 10 seconds, then off, repeatedly.

Maybe you have a hardware problem

Code:
;

hexreader, i can compile the program with MPLAB and write it to the 887, but nothing happens, i have an EasyPIC6 and can write one of the company's demo programs onto the same uC and it works fine (attached just change from .txt to .hex).. i have an 8Mz OSC hooked up to the uC but i have nothing happening.. no leds flashing or anything.

i have compiled almost identical code for a 18F4550 using

Code:
	CONFIG FOSC = XTPLL_XT		;XT oscillator, PLL Enabled XT used by USB

CONFIG PLLDIV = 2

and the PORTB LED's blink, this is using the same EasyPIC6 not changing anyting except the uC.. but for only about 2secconds.. i have to use CONFIG PLLDIV = 12 for it to make 10secconds (timed with a stopwatch).. it seems i dont understand the PLLDIV setting as i thought = 2 would mean the CPU would be running at 8Mhz/4(instruction time) = 2 Mhz

that 10 second delay was straight from Microchip PIC, ASM Delay Code, Code Generator and i chose 8Mhz.. should i be choosing 2Mhz as this is the actual CPU clock? or am i getting confused? surely choosing 2Mhz would just make the routine shorter and having an 8MHz FOSC connected would result in a delay that is very very short in time.

as for the 16F887 just not doing anything.. im stuck? is there some setting im overlooking?

#### Attachments

• Led_Curtain.txt
563 bytes · Views: 6
Last edited:

What programmer are you using? is it the EP6 on-board "micro ICD" programmer, or an external Microchip ICD2 (or ICD3) ?

Your picture shows using debug mode. I presume you switched to release mode before assembling?

Using MikroE interface with on-board programmer means setting configuration bits manually.

Can't think what else to suggest right now....

#### 3BABY

##### Member level 5
What programmer are you using? is it the EP6 on-board "micro ICD" programmer, or an external Microchip ICD2 (or ICD3) ?

Your picture shows using debug mode. I presume you switched to release mode before assembling?

Using MikroE interface with on-board programmer means setting configuration bits manually.

Can't think what else to suggest right now....

I didnt know you had to manualy switch from Dubug mode, when i get home ill recompile and write the program,

im using the MikroE onboard programmer.. arnt we setting the config bits at the start of the code anyways? so this should not be an issue?

il let you know what happens.. cheers

#### 3BABY

##### Member level 5
What programmer are you using? is it the EP6 on-board "micro ICD" programmer, or an external Microchip ICD2 (or ICD3) ?

Your picture shows using debug mode. I presume you switched to release mode before assembling?

Using MikroE interface with on-board programmer means setting configuration bits manually.

Can't think what else to suggest right now....

and still have nothing happening on PORTB.. is this a configuration issue or what im stumped.. any chance i could send you my HEX to try on your system?

This has to be a config problem or my MPLAB is not happy, i tried using the template and just putting in the delay and main, and register defs and i get that same error "," illegal at this point after _CONFIG1, and _CONFIG2,

Code:
	__CONFIG    _CONFIG1, _LVP_OFF & _FCMEN_ON & _IESO_OFF & _BOR_OFF & _CPD_OFF & _CP_OFF & _MCLRE_ON & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT
__CONFIG    _CONFIG2, _WRT_OFF & _BOR21V

Last edited:

I think the problem is with configuration bits.

MikroE software ignores config bit settings in code and seems to ignore config in .hex files too.

Try manually selecting the correct PIC and setting all config bits manually just before writing

If you have an ICD2 or ICD3, it is a better option for programming, as it does preserve config bit settings

#### 3BABY

##### Member level 5
I think the problem is with configuration bits.

Try manually selecting the correct PIC and setting all config bits manually just before writing

do you mean by going to the top of MPLAB and selecting "configure" => configuration bits? if so i have tried that and compiled again but still not output.

or is there a different way to manually set config bits?

thanks

No.

MPLAB does everything correctly.

It is the MikroE Programmer software that throws away the config bits, and forces you to select them manually.

How are you burning the PIC?

I assume that you use PicFlash software and the EasyPIC6 on-board Mikro-ICD hardware, but maybe I guess wrong.

Maybe you could explain your set up in more detail

#### 3BABY

##### Member level 5
No.

MPLAB does everything correctly.

It is the MikroE Programmer software that throws away the config bits, and forces you to select them manually.

How are you burning the PIC?

I assume that you use PicFlash software and the EasyPIC6 on-board Mikro-ICD hardware, but maybe I guess wrong.

Maybe you could explain your set up in more detail

im using the mikroProg Suite (link to pdf) .. i just have the EasyPIC6 connected to my PC via USB..

ok so this is strange.. when i clicked on the "config" tab i had nothing it was just blank.. so i just downloaded mikroProg suite again and reinstalled it and now i can see the settings in the config tab (please see pic) .. this is while power is on on the EasyPIC and i can load my HEX.. but if i select XT as the oscillator the PORTB leds light up but it looks like they must be going very fast as they are dim to look at.. they definitely do not go on and off for 10secs i have even tried calling the 10second delay 4 times per on/off and nothing changes.. i have a 8Mhz crystal on the board at the moment. just now as im writing this i have pulled the 8Mhz crystal out and put a 4Mhz one in.. no change to the LEDs.. i have pulled the crystal out all together and pressed the reset button.. no change to the LEDs.. whats going on? edit... check out pic.. its not the best but you can see PORTB 0-1 are bright and the rest are dim

another update.. ive just modified code to MOVLW b'10101010' PORTD , 10sec delay then MOVLW b'01010101' PORTD then 10secs and its just sitting at 01010101 and not "toggling" .. so the code must not be running?

Last edited:

Now we are getting somewhere....

I would choose HS oscillator, though XT would probably work

Disable LVP (low voltage programming). My guess is that this may be the setting that really matters. With LVP disabled, everything might start to work right - fingers crossed.

#### 3BABY

##### Member level 5
Now we are getting somewhere....

I would choose HS oscillator, though XT would probably work

Disable LVP (low voltage programming). My guess is that this may be the setting that really matters. With LVP disabled, everything might start to work right - fingers crossed.

AND WE HAVE A WINNER!! that worked! its giving me a good 10second delay with the 8Mhz crystal... ive never had to use the config tab when programming the 18F4550's, why would the programmer override the .HEX?

just on another not when using the same code on a 4550 like i mentioned before it was giving me a delay of around 2seconds.. i was using the below. i had to change the PLLDIV to 12 to get it to delay for 10secconds.. does this sound correct? wouldnt that mean the CPU was running at 250KHz?

CONFIG FOSC = XTPLL_XT ;XT oscillator, PLL Enabled XT used by USB

CONFIG PLLDIV = 2

thanks for all your help btw!!!

why would the programmer override the .HEX?
Good question, one for MikroE to answer. It is a very annoying feature of MikroE tools that configuration can only be set manually. There is no sign that MikroE will ever change this highly frustrating policy

ive never had to use the config tab when programming the 18F4550's
Then I would guess that the default settings just happened to give a working option. You just got lucky.

PIC18F4550 has many, many oscillator options which are really hard to configure correctly and to understand. It is a poor choice of chip to learn with for this reason.

PIC18 is capable of running much faster than PIC16.

I would run PIC18F4550 at maximum speed 48MHz and adjust your delay routine to suit. Rather than bring PIC18 down to PIC16 speeds.

I will leave you to study the PIC18F4550 datasheet ( oscillator section) to try and understand all of the different options. I do not have the patience. The oscillator block diagram is the best place to start.

Good luck

Status
Not open for further replies.


text:
# Showing unitary equivalence

How can it be shown that $UU^{*} = I$ where $U$ is a square matrix of an operator on a complex vector space implies that $\langle Ux, Uy\rangle = \langle x, y\rangle$?

-

Hint: For adjoint operators you have $$(Ax,y)=(x,A^{*}y)$$
You may try to expand the summation as $(UX,UY)=\sum_{i}(\sum_{j}u_{ij}x_{j}\overline{\sum_{j}u_{ij}y_{j}})$, etc. But this is usually quite messy. – Kerry Oct 10 '11 at 17:06


text:
# Physics Questions and Answers – Potential Energy of a System of Charges

«
»

This set of Physics Online Quiz for Schools focuses on “Potential Energy of a System of Charges”.

1. The work done to move a charge of 20C by a distance of 2cm is 2J. What is the potential difference between those two points?
a) 1V
b) 0.1V
c) 10V
d) 20V

Explanation: Work done to move a charge q in a potential difference of V is equal to q*V. According to the question, 2J=20C*Potential difference. Therefore, potential difference=$$\frac {2}{20}$$V=0.1V. The definition of 1J thus becomes, work done to move a charge of 1C from one point to another where the potential difference between the two points is 1V.

2.What should be the value of Q so that the potential energy of the system is zero?

a) 2q
b) $$\frac {-q}{2}$$
c) √2 q
d) $$\frac {-2q}{(2 + \sqrt 2)}$$

Explanation: The distance between the charges Q and +q is √2 a according to Pythagoras theorem. Therefore, the total potential energy of the system becomes (Q*$$\frac {q}{a}$$) + (q*$$\frac {q}{a}$$) + (Q*$$\frac {q}{\sqrt 2a}$$). But according to the question, the total potential energy is zero, i.e. (Q*$$\frac {q}{a}$$) + (q*$$\frac {q}{a}$$) + (Q*$$\frac {q}{\sqrt 2a}$$) = 0. Therefore, simplifying the equation, we get Q=$$\frac {-2q}{(2+\sqrt 2)}$$.

3. +q charges are placed at a, 3a, 5a… (up to infinity) and –q charges are placed at 2a, 4a, 6a….. (up to infinity). What is the total potential energy at origin (0, 0)?
a) Zero
b) $$\frac {q}{a}$$
c) $$\frac {(q \, log2)}{a}$$
d) $$\frac {qe^2}{a}$$

Explanation: The total potential energy at the origin due to the system is V=$$\frac {q}{a} – \frac {q}{2a} + \frac {q}{3a} – \frac {q}{4a} + \frac {q}{5a}$$……(up to infinity), where a, 2a, 3a… are the distances of the charges from the origin. Now, taking $$\frac {q}{a}$$ common from the terms, we get V=$$\frac {q}{a} (1 – \frac {1}{2} + \frac {1}{3} – \frac {1}{4} + \frac {1}{5})$$. By substituting the expansion of log2, we can get V=$$\frac {(q \, log2)}{a}$$.
Note: Join free Sanfoundry classes at Telegram or Youtube

4. Four point charges 2*10-9C, 1*10-9C, -2*10-9C, 3*10-9C are placed at the corners of a square of side length √2m. What is the electric potential at the center of the square?
a) 36V
b) -36V
c) 2*10-9V
d) Zero

Explanation: Distance of the center of the square from the corner points=√2*$$\frac {\sqrt 2}{2}$$m=1m. Therefore, electric potential at the center of the square due to the charges = V=$$\frac {1}{4\pi \epsilon} \frac {(2*10-9+1*10-9-2*10-9+3*10-9)}{1}$$=9*109*(2*10-9+1*10-9-2*10-9+3*10-9)=9*(2+1-2+3) =36V.

5. If three equal charges are placed at the corners of an equilateral triangle, the potential at the center of the triangle will be zero.
a) True
b) False

Explanation: Electrostatic potential at a distance r from a point charge q is $$\frac {1}{4 \pi \epsilon} * \frac {q}{r}$$. Therefore, adding this term three times, we get some positive value, not zero. Therefore, the potential energy at the center of the triangle is positive, not zero.
Take Physics - Class 12 Mock Tests - Chapterwise!
Start the Test Now: Chapter 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

6. What is the potential energy at the center of an equilateral triangle if +5esu, +5esu and -10esu are placed at the corners of the triangle? The triangle has a side length of √3cm.
a) 20V
b) 5V
c) $$\frac {5}{3}$$V
d) 0V

Explanation: Distance of the center of the triangle from every corner point is = $$\frac {2}{3} * \frac {\sqrt 3}{2}$$ * √3cm=1cm [as we know that the center divides the median in a 2:1 ratio and the length of the median is $$\frac {2}{3}$$*side length]. Therefore, the potential at the center is =$$\frac {5}{1} + \frac {5}{1} -\frac {10}{1}$$=0 esu Volt.

7. +q charges are placed at the points (1, 0), (2, 0), (4, 0), (8, 0) …. (up to infinity). What is the potential at the origin due to these charges?
a) $$\frac {2q}{3}$$
b) 2q
c) $$\frac {q}{3}$$
d) Infinity

Explanation: Electric potential due to the charges at the origin= q*$$(\frac {1}{1} + \frac {1}{2} + \frac {1}{4} + \frac {1}{8} +…..=q*\frac {1}{1-\frac {1}{2}})$$=2q [by applying the formula of infinite G.P. series]. It can be shown that if the charges are alternately positive and negative, then the potential at the center would be $$\frac {2q}{3}$$ .

Sanfoundry Global Education & Learning Series – Physics – Class 12.

To practice Physics Online Quiz for Schools, here is complete set of 1000+ Multiple Choice Questions and Answers.


text:
• ### Thermodynamic signatures of the field-induced states of graphite(1705.07056)

May 19, 2017 cond-mat.str-el
When a magnetic field confines the carriers of a Fermi sea to their lowest Landau level, electron-electron interactions are expected to play a significant role in determining the electronic ground state. Graphite is known to host a sequence of magnetic field-induced states driven by such interactions. Three decades after their discovery, thermodynamic signatures of these instabilities are still elusive. Here, we report the first detection of these transitions with sound velocity. We find that the phase transition occurs in the vicinity of a magnetic field at which at least one of the Landau levels cross the Fermi energy. The evolution of elastic constant anomalies with temperature and magnetic field draws a detailed phase diagram which shows that the ground state evolves in a sequence of thermodynamic phase transitions.Our analysis indicates that electron-electron interaction is not the sole driving force of these transitions and that lattice degrees of freedom play an important role.
• ### Quantum interference in a macroscopic van der Waals conductor(1609.08026)

Quantum corrections to charge transport can give rise to an oscillatory magnetoconductance, typically observed in mesoscopic samples with a length shorter than or comparable with the phase coherence length. Here, we report the observation of magnetoconductance oscillations periodic in magnetic field with an amplitude of the order of $e^2/h$ in macroscopic samples of Highly Oriented Pyrolytic Graphite (HOPG). The observed effect emerges when all carriers are confined to their lowest Landau levels. We argue that this quantum interference phenomenon can be explained by invoking moir\'e superlattices with a discrete distribution in periodicity. According to our results, when the magnetic length $\ell_B$, the Fermi wave length $\lambda_F$ and the length scale of fluctuations in local chemical potential are comparable in a layered conductor, quantum corrections can be detected over centimetric length scales.
• ### Anisotropic and strong negative magneto-resistance in the three-dimensional topological insulator Bi2Se3(1608.03615)

Aug. 11, 2016 cond-mat.mes-hall
We report on high-field angle-dependent magneto-transport measurements on epitaxial thin films of Bi2Se3, a three-dimensional topological insulator. At low temperature, we observe quantum oscillations that demonstrate the simultaneous presence of bulk and surface carriers. The magneto- resistance of Bi2Se3 is found to be highly anisotropic. In the presence of a parallel electric and magnetic field, we observe a strong negative longitudinal magneto-resistance that has been consid- ered as a smoking-gun for the presence of chiral fermions in a certain class of semi-metals due to the so-called axial anomaly. Its observation in a three-dimensional topological insulator implies that the axial anomaly may be in fact a far more generic phenomenon than originally thought.
• ### Thermal conductivity across the metal-insulator transition in single crystalline hyperkagome Na$_{3+x}$Ir$_3$O$_8$(1410.8792)

Oct. 31, 2014 cond-mat.str-el
The hyperkagome antiferromagnet Na$_{4}$Ir$_3$O$_8$ represents the first genuine candidate for the realisation of a three-dimensional quantum spin-liquid. It can also be doped towards a metallic state, thus offering a rare opportunity to explore the nature of the metal-insulator transition in correlated, frustrated magnets. Here we report thermodynamic and transport measurements in both metallic and weakly insulating single crystals down to 150 mK. While in the metallic sample the phonon thermal conductivity ($\kappa^{ph}$) is almost in the boundary scattering regime, in the insulating sample we find a large reduction $\kappa^{ph}$ over a very wide temperature range. This result can be ascribed to the scattering of phonons off nanoscale disorder or off the gapless magnetic excitations that are seen in the low-temperature specific heat. This works highlights the peculiarity of the metal-insulator transition in Na$_{3+x}$Ir$_3$O$_8$ and demonstrates the importance of the coupling between lattice and spin degrees of freedom in the presence of strong spin-orbit coupling.


text:
Version:

Computes the inverse hyperbolic sine of the input elements.

Syntax

c = asinh(a)

a

Real or complex scalar or array of any dimension.

c

Inverse hyperbolic sine of the elements in a. c is a scalar or an array of the same size as a.


text:
# Back from the Mac

iOS 6 ends up bringing a lot of interesting new features to the regular user, and looking over the API differences, not a lot on the developer side of things. iOS 5 was a gigantic leap for developers, starting with ARC, Storyboards, and a bajillion1 APIs opened up. I’m willing to bet that this is becoming Apple’s calling card. One on, one off, is now to be prevalent in designing both hardware and software.

1. That’s a technical term for all you non-tech savvy folk. ↩

# WWDC 2012 Predictions

I figure, might as well get these on the record, and afterwards we can all laugh at how wrong I am.

# A Letter

Below is a letter that I wrote.

# Thoughts on Apple’s Messages

The idea of a continuous client is something that has sent nerds’ hearts a flutter for a long time. No matter what device you pick up, you’ll have an up to date conversation log.


text:
# zbMATH — the first resource for mathematics

A three-node $$C^0$$ ANS element for geometrically nonlinear structural analysis. (English) Zbl 1083.74588
Summary: A three-node macro triangular element is proposed for geometrically nonlinear analysis of plates and shells. This study concentrates on not only improving the performance of the element by reducing the locking effect but also retaining the geometrical advantages of three-node triangular element in pre-processing. The assumed natural strain (ANS) formulation is adopted to suppress the locking effect. The macro element strategy improves the element accuracy and enhances the effectiveness of ANS formulation by incorporating three sub-triangles. The resulting element configuration fits on the conventional three-node triangular mesh after condensing out the virtual center node. Numerical tests evaluate the element for geometrically nonlinear analysis of plates and shells. The results demonstrate that the present element significantly improves the accuracy in nonlinear analysis.

##### MSC:
 74S05 Finite element methods applied to problems in solid mechanics 74K20 Plates 74K25 Shells
##### Keywords:
locking effect; macro element; pre-processing
Full Text:


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Composition of two absolute functions

$f$ and $g$ are two absolutely contiunous functions and $f$ is monotone.

Is $f(g)$ necessarily an absolutely continuous function? Why not any counter example?

Thanks a lot!!

-
What did you try? – Davide Giraudo Sep 13 '12 at 8:54
Refer to the book Measure Theory by V.I. Bogachev. There is hint for your problem. Try online books. :) – Babak S. Sep 13 '12 at 9:25
Babak I am curious about f(g) not g(f) thanks for the book though.. Davide I get stuck in the second stage when composed because disjointness criterion gets lost... – Salih Ucan Sep 14 '12 at 1:29

Let $\{x_n\}_1^\infty$, $\{y_n\}_1^\infty$ be two sequences of point in $I = [0, 1]$ such that $$x_1 = 0\\ x_n\to 1\\ x_n < y_n < x_{n+1} \quad n=1, 2, \dotsc$$ Let's define a function $h$ on the interval I setting $$h(x) = \begin{cases} \frac 1 {(y_n - x_n)(n + 1)^2} &x\in [x_n, y_n)\\ -\frac 1 {(x_{n + 1} - y_n)(n + 1)^2} &x\in [y_n, x_{n + 1}) \end{cases}$$ $h$ is summable \begin{align} \int_I \lvert h(x)\rvert dx &= \sum_{n = 1}^\infty \frac {y_n - x_n} {(y_n - x_n)(n + 1)^2} + \sum_{n = 1}^\infty \frac {x_{n + 1} - y_n} {(x_{n + 1} - y_n)(n + 1)^2} \\ &= 2\sum_{n = 1}^\infty \frac 1 {(n + 1)^2} \\ &= \pi^2/3 - 2 \end{align} Of course $$f(x) := \int_0^x h(t) dt, \quad x\in I$$ is absolutely continuous, moreover $$f(x_k) = \int_0^{x_k} h(t) dt = \sum_{n = 1}^{k - 1} \frac 1 {(n + 1)^2} - \sum_{n = 1}^{k - 1} \frac 1 {(n + 1)^2} = 0\\ f(y_k) = \int_0^{y_k} h(t) dt = \sum_{n = 1}^{k} \frac 1 {(n + 1)^2} - \sum_{n = 1}^{k - 1} \frac 1 {(n + 1)^2} = \frac 1 {(n + 1)^2}$$ From the above equalities we deduce the the total variation $V$ of the function $\sqrt f$ isn't finite $$V \geq \sum_{n = 1}^{\infty} \left\vert \sqrt {f(y_n)} - \sqrt{f(x_n)} \right\vert = \sum_{n = 1}^{\infty} \frac 1 {n + 1} = \infty$$ In particular $\sqrt f$ is not absolutely continuous even if it is the composition of two absolutely continuous functions, $f$ and $$g: x\in I \to \sqrt x \in I$$
Same idea as @AlbertH, but a bit simpler to write: $f(x)=x^2 \sin^2 \frac{\pi }{2x}$ is Lipschitz on $[0,1]$ because $f'$ is bounded. Hence, $f$ is absolutely continuous. However, $\sqrt{f}$ has infinite variation on $[0,1]$, which one can demonstrate by summing $|f(\frac1n)-f(\frac1{n+1})|$.


text:
Publication
Title
$V_{6}O_{13}$ films by control of the oxidation state from aqueous precursor to crystalline phase
Author
Abstract
 An aqueous deposition process for V6O13 films is developed whereby the vanadium oxidation state is continuously controlled throughout the entire process. In the precursor stage, a controlled wet chemical reduction of the vanadium(V) source with oxalic acid is achieved and monitored by (51)Vanadium Nuclear Magnetic Resonance (V-51-NMR) and Ultraviolet-Visible (UV-Vis) spectroscopy. The resulting vanadium(IV) species in the aqueous solution are identified as mononuclear citrato-oxovanadate(IV) complexes by Electron Paramagnetic Resonance (EPR) and Fourier Transform Infra-Red (FTIR) spectroscopy. This precursor is successfully employed for the deposition of uniform, thin films. The optimal deposition and annealing conditions for the formation of crystalline V6O13, including the control of the vanadium oxidation state, are determined through an elaborate study of processing temperature and O-2 partial pressure. To ensure a sub 100 nm adjustable film thickness, a non-oxidative intermediate thermal treatment is carried out at the end of each deposition cycle, allowing maximal precursor decomposition while still avoiding V(IV) oxidation. The resulting surface hydrophilicity, indispensable for the homogeneous deposition of the next layer, is explained by an increased surface roughness and the increased availability of surface vanadyl groups. Crystalline V6O13 with a preferential (002) orientation is obtained after a post deposition annealing in a 0.1% O-2 ambient for thin films with a thickness of 20 nm.
Language
English
Source (journal)
Journal of the Chemical Society : Dalton transactions. - London, 1972 - 1999
Publication
London : Chemical Society , 2013
ISSN
0300-9246 [print]
2050-5671 [online]
Volume/pages
42 :4 (2013) , p. 959-968
ISI
000312659200019
Full text (Publisher's DOI)
UAntwerpen
 Faculty/Department Research group Project info The elucidation of complex electron paramagnetic resonance (EPR) spectra of novel stable radical cations - an interdisciplinary approach. Publication type Subject Affiliation Publications with a UAntwerp address


text:
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Current Directions in Biomedical Engineering

Joint Journal of the German Society for Biomedical Engineering in VDE and the Austrian and Swiss Societies for Biomedical Engineering

Editor-in-Chief: Dössel, Olaf

Editorial Board: Augat, Peter / Buzug, Thorsten M. / Haueisen, Jens / Jockenhoevel, Stefan / Knaup-Gregori, Petra / Kraft, Marc / Lenarz, Thomas / Leonhardt, Steffen / Malberg, Hagen / Penzel, Thomas / Plank, Gernot / Radermacher, Klaus M. / Schkommodau, Erik / Stieglitz, Thomas / Urban, Gerald A.

Open Access
Online
ISSN
2364-5504
See all formats and pricing
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Volume 2, Issue 1

Continuous non-invasive monitoring of blood pressure in the operating room: a cuffless optical technology at the fingertip

Josep Solà
• Corresponding author
• CSEM – Centre Suisse d’Electronique et Microtechnique, Jacquet-Droz 1, CH-2002 Neuchâtel, Switzerland
• Email
• Other articles by this author:
• De Gruyter OnlineGoogle Scholar
/ Martin Proença
• CSEM – Centre Suisse d’Electronique et Microtechnique, Jacquet-Droz 1, CH-2002 Neuchâtel, Switzerland
• Other articles by this author:
• De Gruyter OnlineGoogle Scholar
/ Fabian Braun
• CSEM – Centre Suisse d’Electronique et Microtechnique, Jacquet-Droz 1, CH-2002 Neuchâtel, Switzerland
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/ Nicolas Pierrel
• CHUV – Centre Hospitalier Universitaire Vaudois, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland
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/ Yan Degiorgis
• CHUV – Centre Hospitalier Universitaire Vaudois, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland
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/ Christophe Verjus
• CSEM – Centre Suisse d’Electronique et Microtechnique, Jacquet-Droz 1, CH-2002 Neuchâtel, Switzerland
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/ Mathieu Lemay
• CSEM – Centre Suisse d’Electronique et Microtechnique, Jacquet-Droz 1, CH-2002 Neuchâtel, Switzerland
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/ Mattia Bertschi
• CSEM – Centre Suisse d’Electronique et Microtechnique, Jacquet-Droz 1, CH-2002 Neuchâtel, Switzerland
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/ Patrick Schoettker
• CHUV – Centre Hospitalier Universitaire Vaudois, Rue du Bugnon 46, CH-1011 Lausanne, Switzerland
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Published Online: 2016-09-30 | DOI: https://doi.org/10.1515/cdbme-2016-0060

Abstract

Routine monitoring of blood pressure during general anaesthesia relies on intermittent measurements with a non-invasive brachial cuff every five minutes. This manuscript provides first experimental evidence that a physiology-based pulse wave analysis algorithm applied to optical data (as provided by a standard fingertip pulse oximeter) is capable of accurately estimating blood pressure changes in-between cuff readings. Combined with the routine use of oscillometric cuffs, the presented novel approach is a candidate technology to increase patient safety by providing beat-to-beat hemodynamic measurements without the need of invasive monitoring procedures.

1 Introduction

Blood pressure and heart rate monitoring belong to the minimal standards for basic anaesthetic monitoring [1]. Still today, the non-invasive measurement of blood pressure is performed with brachial inflation cuffs placed around the arm. However, these devices only provide intermittent measurements of blood pressure during the interventions, i.e. every 2–5 min. For patient safety reasons, beat-to-beat blood pressure readings are mandatory in critical patients during long and complex interventions. Unfortunately, the routine procedure to obtain reliable continuous blood pressure readings relies on arterial invasive catheters, with their non-negligible associated morbidity issues [2]. Non-invasive and continuous blood pressure measurement devices have been tested in the past, but their accuracy and reliability have been repeatedly questioned [3], in particular when aiming at replacing existing procedures. Even more, high costs and cumbersomeness of existing non-invasive beat-by-beat devices impede their introduction into daily anaesthesia practices.

This manuscript presents first experimental evidence on the feasibility of tracking beat-by-beat changes of blood pressure in humans during induction of general anaesthesia by simple optical means. The presented technology relies on the physiological analysis of transmission photoplethysmographic signals measured at the fingertip. Such signals are recorded by commercial pulse oximeters, which are routinely applied to almost every patient. While the presented approach does not aim at replacing oscillometric gold-standard monitoring, it introduces an appealing approach to continuously estimate blood pressure measurements in-between two cuff inflations, thus allowing the detection of sudden blood pressure changes and thereby increasing the patient’s safety.

Because no additional monitoring equipment is required in the operating room, this optical technology appears as an appealing candidate to improve non-invasive monitoring capabilities during general anaesthesia. Figure 1 illustrates the status of the novel technology within the constellation of existing monitoring means in the operating room.

Figure 1

Summary of available blood pressure (BP) monitoring technologies in the operating room.

2 Materials

The clinical study (ClinicalTrials.gov NCT02651558) described in this section is compliant with all relevant Swiss ethics, regulations and institutional policies and in accordance with the tenets of the Helsinki Declaration. Informed consent was obtained from all individuals before enrolment at CHUV – University Hospital of Lausanne.

Patients were placed on the operating table and monitoring was carried out via the Philips monitor IntelliVue MX800. Monitoring consisted of a 3-lead electrocardiogram, non-invasive blood pressure cuff measurements at the left arm and oxygen fingertip saturation readings at the right index. Under local anaesthesia, a dedicated catheter (BD Arterial Cannula 20G/1.1 mm × 45 mm, Becton Dickinson Infusion Therapy Syst. Inc., UT, USA) was inserted into the right radial artery, allowing beat-to-beat continuous blood pressure monitoring. General anaesthesia was then provided by the anaesthetist in charge of the patient, in accordance with the standard practice of the department: propofol (2 mg/kg) for induction, fentanyl (3 μg/kg) for analgesia, and rocuronium (0.6 mg/kg) for neuromuscular blockade; endotracheal intubation followed.

Recording of continuous invasive blood pressure signals, non-invasive fingertip photoplethysmographic signals (i.e. Pleth Wave), and electrocardiogram was performed at 500 Hz by ixTrend® – software for Philips IntelliVue monitors. As the clinical study is ongoing, only the first three patients showing good raw signal quality (by an unsupervised quality index) were used to show first experimental evidence.

3.1 Overall methodology

The novel optical technology relies on the extraction of physiology-based pulse wave analysis (PWA) features from raw transmission photoplethysmographic signals. These physiological features are later projected into blood pressure values by means of intermittent oscillometric measurements provided by a brachial cuff (see Figure 2).

Figure 2

Overall methodology: blood pressure estimates interpolate patient’s hemodynamic changes in-between two oscillometric measurement.

3.2 Extraction of PWA features

Raw photo-plethysmographic signals are acquired by a fingertip pulse oximetry probe. While for the current study a commercial transmission probe is used, any other means to acquire a surrogate measure for peripheral arterial pulsatility is adapted for this methodology.

After a pre-processing and denoising procedure, a PWA technique is applied to each arterial pulse [4]. The implemented PWA algorithm extracts features from each pulse based on the wave reflection theory of the arterial system [5]. The algorithm assumes that arterial pulses propagate along the arterial tree being reflected at each arterial branching. The resulting arterial pulses are thus the superposition of forward and backward waves interfering at various locations of the arterial tree.

Given the arterial topology of a particular patient, changes in blood pressure modify the velocity at which arterial pulses propagate, reshaping the individual mixture of incident and reflected waves. These morphological changes are quantified via the implemented PWA algorithm as modifications of the patients’ arterial pulsatility patterns. Pulsatility pattern changes are indirect indicators of the underlying changes in propagation characteristics, and thus, of the underlying changes of central blood pressure. Therefore the outcome of the implemented PWA algorithm is a vector of physiologically meaningful features containing information on the patient’s central blood pressure status.

3.3 Calibration to brachial cuff values

While containing meaningful physiological information, the feature vector extracted from the PWA algorithm does not yet relate to blood pressure values in mm Hg.

In the context of a methodology to extract beat-to-beat blood pressure estimates in-between two cuff measurements a dedicated (re-)calibration algorithm is thus needed. The aim of this algorithm is to map subject-dependent changes of the PWA feature vector xi into actual changes of blood pressure. During each recalibration at instant i, the availability of intermittent cuff-based measurements yi is used as a reference to re-estimate the parameters $p^i$ of a mapping function f as it is depicted by equation 1. A forgetting factor λ can be used to smooth pressure estimates in time.

$p^i=(1−λ)p^i−1+λargminpi∥yi−f(pi,xi)∥2$(1)

4 Results and discussion

Based on the previously described methodology, first experimental evidence on the performance of the novel cuffless technique is provided here. Figures 35 illustrate the results of cuffless systolic blood pressure estimations compared to invasive reference measurements. Each figure corresponds to data recorded during induction of anaesthesia on one patient. Each data point in these figures corresponds to a single heartbeat. Calibration with reference measurement was performed every 5 min.

Figure 3

Performance of the cuffless blood pressure estimation technique on a particular study patient during induction of anesthesia. Each data point corresponds a patient’s heart beat. Temporal evolution of invasive systolic blood pressure is displayed as ±8 mm Hg range (shaded in grey).

Figure 4

Performance of the cuffless blood pressure estimation technique on a particular study patient during induction of anesthesia. Each data point corresponds a patient’s heart beat. Temporal evolution of invasive systolic blood pressure is displayed as ±8 mm Hg range (shaded in grey).

Figure 5

Performance of the cuffless blood pressure estimation technique on a particular study patient during induction of anesthesia. Each data point corresponds a patient’s heart beat. Temporal evolution of invasive systolic blood pressure is displayed as ±8 mm Hg range (shaded in grey).

The first row in each figure depicts correlation plots between invasive systolic blood pressure values and heart rate estimates (left plot) or cuffless blood pressure estimates (right plot), respectively. Note that in current clinical practice, when only intermittent blood pressure measurements are available, anaesthetists fully rely on heart rate measurements to infer blood pressure changes.

The second row in each figure depicts Bland-Altman plots when comparing invasive systolic blood pressure values against cuffless blood pressure estimates. Due to the re-calibration procedures, overall bias are within a reasonable range (|μ| < 4 mm Hg). Standard errors of the estimates σ are all smaller than 8 mm Hg, and thus comply with the specifications of the AAMI standard [6].

The third row in each figure depicts the temporal evolution of invasive systolic blood pressure during anesthesia induction (±8 mm Hg range shaded in grey), and simultaneous cuffless estimates. Note that calibration periods are illustrated by black boxes marked as “CAL”. It is important to note that the novel cuffless method was able to detect blood pressure changes in between calibration periods for all the three patients analyzed.

5 Conclusion

This manuscript presented first experimental evidence for the feasibility of estimating blood pressure changes in the operating room by means of a simple optical probe at the fingertip, which is routinely applied to every patient.

During all anaesthetic procedures and surgeries, the patient’s oxygenation, ventilation, circulation and temperature must be continuously monitored. To cope with these requirements, and in order to increase patients’ safety, international standards for safe practice of anaesthesia have been implemented and consist of cumbersome equipment.

While comprehensive statistical analysis of the performances of the novel approach will be presented at finalisation of the ongoing clinical study, these preliminary results support the hypothesis that physiology-based PWA algorithms applied to standard photo-plethysmographic signals might contain sufficient information to deduce blood pressure changes during general anaesthesia, without the need of additional monitoring equipment.

Technological advances such as the one herein presented appear as an interesting alternative, aiming at simplifying patient access, and potentially decreasing morbidity associated to invasive monitoring in the operating room.

Authors’ Statement

Research funding: The author state no funding involved. Conflict of interest: Authors state no conflict of interest. Material and Methods: Informed consent: Informed consent is not applicable. Ethical approval: The conducted research is not related to either human or animal use.

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Published Online: 2016-09-30

Published in Print: 2016-09-01

Citation Information: Current Directions in Biomedical Engineering, Volume 2, Issue 1, Pages 267–271, ISSN (Online) 2364-5504,

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