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# Tag Info

## New answers tagged exoplanet

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A rough back-of-the-envelope way of seeing what's going on... The tidal force is due to the difference in gravitational force, so follows an inverse cube law: $$F_\mathrm{tide} \propto M_\ast R^{-3}$$ where $M_\ast$ is the stellar mass and $R$ is the distance. So at the same distance from a less massive star, the tidal force will indeed be weaker. But ...

3

This answer applies to the simplest case: a static binary and a point source. In the binary case, $u(t)$ describes how close each point in the source trajectory comes to (what you have defined as) the origin of the binary axis. The solution is non-trivial. It involves finding the roots of a 5th order complex polynomial. You can look for example at how ...

2

The only way to answer the question about stability is to do the integration, because this problem does not have an analytic solution. There are approximate solutions for the stability of two-planet systems (although these are based on a somewhat weaker constraint that allows the outermost object to escape to infinity) but they do not necessarily generalise ...

1

(Some of) These plots are incorrect. Whilst Rayleigh scattering has a steep dependence on wavelength $(\propto \lambda^{-4})$, it cannot scatter what is not there. There is almost no blue light at all coming from stars with $T_{\rm eff} < 3500$ K. A detailed description of the problem with your calculations(?) is given here with regard to a red giant ...

1

I think the star,its halo and cloud can't be darker than the sky color even early M type still look blindingly bright orange-red on the sky not dim orange-red. The sky color, if heavier i think it will look more "desaturate"(brighter too but not bright to the point it's brighter than the star) and thecolor shift toward the red side(you are correct) that ...

4

> Do other stars have similar gaseous-to-rocky ratios among their planets? For any given stellar system, are there typically as many gaseous planets as there are rocky planets? With the current instruments and methods we have, we can only access certain population of exoplanets. Terrestrial-mass exoplanets are quite hard to find hence we have more ...

6

I am not using TESS to find planets, but I'm reasonably sure that the answer is that nobody has looked very carefully at all the data yet. The TESS data comes in two flavours. There were a subset of about 200,000 stars that were observed with a 2 minute cadence. These targets were chosen to be a combination of bright and small, heavily weighted towards ...

1

The important thing to bear in mind is that WASP-76b is a gas giant (at the time of writing, the NASA Exoplanet Archive gives values of 0.92 Jupiter masses and 1.83 Jupiter radii, so this planet is much less dense than Jupiter is): there's no solid surface for the iron to build up on. Instead what would happen is that the iron would rain down until it ...

2

FFI means "full frame image". It does not contain any tables, so the unhelpful error message is almost certainly due to that. Chapter 2 of the Kepler Archive Manual is essential reading. Light curve files have a file name suffix of .llc or .slc (long and short cadence), as described in that document, and contain binary fits tables that can be opened and ...

12

Radial velocity Radial velocity might be able to detect Jupiter in the 5 or 500 light-years cases unless the solar system were oriented close to face-on. There is nevertheless the potential for confusion with the solar activity cycle at a similar period (this issue has come up for a couple of extrasolar Jupiter-analogues), which may require a very long ...

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The distance moduli at 5, 500, 50,000 and 5,000,000 are -4.1, 5.9, 15.9 and 25.9 respectively. We add that to the absolute visual magnitude of the Sun, 4.8, to get apparent magnitudes of 0.7, 10.7, 20.7 and 30.7 respectively. Most planets are detected by the Doppler wobble in the parent star or if the planet transits in front of the parent star. Some are ...

3

It's usually a good idea to use the main page and follow links there instead of guessing URL; a search for "kepler telescope data" and "tess telescope data" quickly revealed these links: Kepler: https://keplerscience.arc.nasa.gov/data-products.html which links for some data to https://exoplanetarchive.ipac.caltech.edu/index.html TESS: https://heasarc.gsfc....

13

There is no unique definition of Earth-like and it depends on what characteristics are important in the context of discussion. The most simple one is to just compare radii and masses. That is observationally sensible as radius is directly deducable from transits (assuming stellar size known) and mass is often an accessible properties for transiting planets ...

3

The term "stellar component" refers to a part ("component") of a system that is in the form of one or more stars. For example, the Alpha Centauri system has three stellar components: Rigil Kentaurus, Toliman and Proxima Centauri. The planet Proxima Centauri b is also a component of the Alpha Centauri system but it is not a stellar component because it isn't ...

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# C++ - Getting Vertex data from text file into array

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Hi, I have a txt file full of vertex data fort he polygons i want to draw but the problem i am having is reading the numbers both positive and negitive seperatored by space, 9 -4 7 -1 -4 0 into the array without putting in the spaces and the ''-'' sysmbo on its own. I anyone could help, i would be most grateful. Thanks, Paul

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I'm not sure why you're not doing binary, or if there are any newlines ("\n") but here is a possible hack.

fscanf("%f %f %f", &Point.x, &Point.y, &Point.z);

I don't know your file format so it's kinda hard to help any more than that.
Good Luck,
~S'Greth

Edited by - SGreth on June 13, 2001 8:06:48 AM

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quote:
Original post by Zeus_666

Hi,
I have a txt file full of vertex data fort he polygons i want to draw but the problem i am having is reading the numbers both positive and negitive seperatored by space,

9 -4 7 -1 -4 0

into the array without putting in the spaces and the ''-'' sysmbo on its own. I anyone could help, i would be most grateful.

Thanks, Paul

To read an integer from a file, you can use the standard extractor operator (>> on an ifstream:
ifstream file;int i;file >> i;

It will read a negative number (-15) as easily as a postive number (15).

To do a loop to read ints, do the following:
while (file >> i){  // do whatever you like with i}

This will read ints from file until an error occurs (i.e. input that cannot be converted to an int), or end-of-file is reached.

Integers in the file have to be separated by whitespace (space, tab, newline).

HTH

Free multiplatform ANSI C++ Standard Library implementation
Visual C++ STL fixes
Visual C++ 6.0 noncompliance issues
C++ FAQ Lite

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But not just int''s, the >> operator can read any standard data type from a file. Since i''m sure you''re using floats or doubles, do something of the following

#include
#include

#define MAX_SIZE 250000
...

ifstream fin;
float n[MAX_SIZE];

fin.open("model_file");
// dont forget to check for errors

fin >> n[0];
for(int i=0; !fin.eof() && i < MAX_SIZE; i++)
fin >> n;

fin.close();

.....
this will read all the data from the file
it keeps track of what''s negative and what''s positive also. As long as they are seperated by spaces or new lines. However, i would suggest you do it in binary like the person who suggested it earlier. If you need help, I have a decent binary file format that makes it easy to use features like index vertex arrays, etc.

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The forums took the header names off my includes.. they were

iostream.h
fstream.h

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You can indeed use the stream extractor and inserter operators for any of the built in types, as Hairu pointed out (thanks).

However, (and this is more to Hairu), I''d like to make some small comments on the code you posted (just to clarify, not to mean any disrespect):

- iostream.h or fstream.h are old, pre standard-C++ headers, and their use is deprecated. All C++ Library headers have no .h. So, #include <iostream>. This also means that the C++ classes and types are in namespace std, so you have to use ''using namespace std'', or specify the scope directly (std::ifstream, for example).
- in your for loop, you only check for eof(). But, there may be other errors, like input that cannot be converted. Better is to use while(f >> n) { ... }
- last but not least: use vector instead of c-style arrays. C-style arrays are error prone, and can be difficult to use.

HTH

Free multiplatform ANSI C++ Standard Library implementation
Visual C++ STL fixes
Visual C++ 6.0 noncompliance issues
C++ FAQ Lite

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Ah, I did not know that you could leave the .h off of those headers. I only did that for the c++ string class. I was wondering though, what exactly did you mean by use vectors instead of arrays? You mean to create a vector structure yourself, or does c/c++ have built in vectors?

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Hi,
Thanks for the help, a few have mentioned doing the file in binary format, how would i go about this?

Thanks, Paul

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Using:

while( !file.eof() )
{
//Do stuff here
}

Will avoid having to use an empty while loop. In the while loop you probably will be storing the stuff in the vector.

"Ogun''s Laughter Is No Joke!!!" - Ogun Kills On The Right, A Nigerian Poem.

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quote:
Original post by EbonySeraph

Using:

while( !file.eof() )
{
//Do stuff here
}

Will avoid having to use an empty while loop. In the while loop you probably will be storing the stuff in the vector.

Actually, it''s better not to use file.eof() in that way. Usually, people write things like
  ifstream file("blabla");while (!file.eof()){ // ... read from file ... // ... do whatever with data read ...}

with the intention of reading data until the end of a file. There is a fundamental flaw in this approach: the eof file flag is only set after attempting to read past the end of a file. Consider this for an input steam mapped to keyboard input. It''s impossible to predict whether or not a character the user typed will be the last one! So the loop above will not reliably read the file.

Better is to use
  while ( file >> i ){ // ... do whatever with data read ...}

in case of formatted input, or
  while ( file.read(buf, n) ){ // ... do whatever with data read ...}

in case of unformatted input. Or you can use something else than a while loop, of course!

HTH

format: plain


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# Vertical line in LaTeX [duplicate]

How can I get this vertical line in LaTeX:

|

I dont see a command for it, and if I type | it becomes horizontal.


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# Convergence of measure on clopen basis implies the existence of a limit measure?

Let $$X$$ be a compact metrizable space. Let $$B$$ be basis for the topology of $$X$$. Assume that all sets in $$B$$ are clopen.

Let $$(\mu_n)_{n=1}^{\infty}$$ be sequence of Borel regular probability measures on $$X$$. Assume that for every $$U\in B$$ the sequence $$(\mu_n(U))_{n=1}^{\infty}$$ converges.

Does this mean that there is a Borel regular probability measure $$\mu$$ on $$X$$ such that $$\lim_{n\rightarrow\infty}\mu_{n}(U)=\mu(U)$$ for all $$U\in B$$?

I read a little about weak-* converges and it seems to be the right notion for this, but I'm not sure.

My knowledge in measure theory is somewhat lacking, but my goal is to understand how to construct such a measure $$\mu$$ completely including the proofs of all required theorems (hence, elementary answers would be great).

Identifying regular Borel measures with bounded linear functionals on $$C(X)$$ we can consider $$(\mu_n)_n$$ to be a sequence in the unit ball of $$C(X)^*$$. By the Banach-Alaoglu theorem it has a weak$$^*$$-cluster point, say $$\mu$$, in the unit ball of $$C(X)^*$$. This means that there is a subsequence, say $$(\mu_{n_k})_k$$, such that $$\int f$$ $$d\mu_{n_k}\rightarrow \int f$$ $$d\mu$$ for all $$f\in C(X)$$. $$\mathcal{X}_U\in C(X)$$ for any clopen $$U\subset X$$, hence $$\mu_{n_k}(U)=\int \mathcal{X}_U$$ $$d\mu_{n_k}\rightarrow \int \mathcal{X}_U$$ $$d\mu=\mu(U)$$. Since $$\lim\limits_{n \rightarrow \infty} \mu_n(U)$$ is assumed to exist we must then have $$\lim\limits_{n \rightarrow \infty} \mu_n(U)=\mu(U)$$.


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Search
Research Article

# The Cost and Impact of Scaling Up Pre-exposure Prophylaxis for HIV Prevention: A Systematic Review of Cost-Effectiveness Modelling Studies

• g.gomez@aighd.org

Affiliation: Department of Global Health, Academic Medical Centre, University of Amsterdam and Amsterdam Institute for Global Health and Development, The Netherlands

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• Affiliation: School of Public Health, Imperial College London, United Kingdom

X
• Affiliation: School of Public Health, Imperial College London, United Kingdom

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• Affiliation: Centre for Patient Safety and Service Quality, Imperial College London, United Kingdom

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• Affiliation: London School of Hygiene and Tropical Medicine, United Kingdom

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• Affiliations: Department of Global Health, Academic Medical Centre, University of Amsterdam and Amsterdam Institute for Global Health and Development, The Netherlands, London School of Hygiene and Tropical Medicine, United Kingdom

X
• Published: March 12, 2013
• DOI: 10.1371/journal.pmed.1001401

## Abstract

### Background

Cost-effectiveness studies inform resource allocation, strategy, and policy development. However, due to their complexity, dependence on assumptions made, and inherent uncertainty, synthesising, and generalising the results can be difficult. We assess cost-effectiveness models evaluating expected health gains and costs of HIV pre-exposure prophylaxis (PrEP) interventions.

### Methods and Findings

We conducted a systematic review comparing epidemiological and economic assumptions of cost-effectiveness studies using various modelling approaches. The following databases were searched (until January 2013): PubMed/Medline, ISI Web of Knowledge, Centre for Reviews and Dissemination databases, EconLIT, and region-specific databases. We included modelling studies reporting both cost and expected impact of a PrEP roll-out. We explored five issues: prioritisation strategies, adherence, behaviour change, toxicity, and resistance. Of 961 studies retrieved, 13 were included. Studies modelled populations (heterosexual couples, men who have sex with men, people who inject drugs) in generalised and concentrated epidemics from Southern Africa (including South Africa), Ukraine, USA, and Peru. PrEP was found to have the potential to be a cost-effective addition to HIV prevention programmes in specific settings. The extent of the impact of PrEP depended upon assumptions made concerning cost, epidemic context, programme coverage, prioritisation strategies, and individual-level adherence. Delivery of PrEP to key populations at highest risk of HIV exposure appears the most cost-effective strategy. Limitations of this review include the partial geographical coverage, our inability to perform a meta-analysis, and the paucity of information available exploring trade-offs between early treatment and PrEP.

### Conclusions

Our review identifies the main considerations to address in assessing cost-effectiveness analyses of a PrEP intervention—cost, epidemic context, individual adherence level, PrEP programme coverage, and prioritisation strategy. Cost-effectiveness studies indicating where resources can be applied for greatest impact are essential to guide resource allocation decisions; however, the results of such analyses must be considered within the context of the underlying assumptions made.

Please see later in the article for the Editors' Summary

## Editors' Summary

### Background

Every year approximately 2.5 million people are infected with HIV, the virus that causes AIDS. Behavioral strategies like condom use and reduction of sexual partners have been the hallmarks of HIV prevention efforts. However, biological prevention measures have also recently been shown to be effective. These include male circumcision, treatment as prevention (treating HIV-infected people with antiretroviral drugs to reduce transmission), and pre-exposure prophylaxis (PrEP), where people not infected with HIV take antiretroviral drugs to reduce the probability of transmission. Strategies such as PrEP may be viable prevention measure for couples in long-term relationships where one partner is HIV-positive and the other is HIV-negative (HIV serodiscordant couples) or groups at higher risk of HIV infection, such as men who have sex with men, and injection drug users.

The findings from recent clinical trials that demonstrate PrEP can reduce HIV transmission have led to important policy discussions and in the US, Southern Africa, and the UK new clinical guidelines have been developed on the use of PrEP for the prevention of HIV infection. For those countries that are considering whether to introduce PrEP into HIV prevention programs, national policy and decision makers need to determine potential costs and health outcomes. Cost-effectiveness models—mathematical models that simulate cost and health effects of different interventions—can help inform such decisions. However, the cost-effectiveness estimates that could provide guidance for PrEP programs are dependent on, and limited by, the assumptions included in the models, which can make their findings difficult to generalize. A systematic comparison of published cost-effectiveness models of HIV PrEP interventions would be useful for policy makers who are considering introducing PrEP intervention programs.

### What Did the Researchers Do and Find?

The researchers performed a systematic review to identify published cost-effectiveness models that evaluated the health gains and costs of HIV PrEP interventions. Systematic reviews attempt to identify, appraise, and synthesize all the empirical evidence that meets pre-specified eligibility criteria to answer a given research question by using explicit methods aimed at minimizing bias. By searching databases the authors identified 13 published studies that evaluated the impact of PrEP in different populations (heterosexual couples, men who have sex with men, and injection drug users) in different geographic settings, which included Southern Africa, Ukraine, US, and Peru.

The authors identified seven studies that assessed the introduction of PrEP into generalized HIV epidemics in Southern Africa. These studies suggest that PrEP may be a cost effective intervention to prevent heterosexual transmission. However, the authors note that funding PrEP while other cost-effective HIV prevention methods are underfunded in this setting may have high opportunity costs. The authors identified five studies where PrEP was introduced for concentrated epidemics among men who have sex with men (four studies in the US and one in Peru). These studies suggest that PrEP may have a substantial impact on the HIV epidemic but may not be affordable at current drug prices. The authors also identified a single study that modeled the introduction of PrEP for people who inject drugs in the Ukraine, which found PrEP not to be cost effective.

In all settings the price of antiretroviral drugs was found to be a limiting factor in terms of affordability of PrEP programs. Behavioral changes and adherence to PrEP were estimated to have potentially significant impacts on program effectiveness but the emergence of drug resistance or PrEP-related toxicity did not significantly affect cost-effectiveness estimates. Several PrEP prioritization strategies were explored in included studies and delivering PrEP to populations at highest risk of HIV exposure was shown to improve cost-effectiveness estimates. However, the extra costs of identifying and engaging with high-risk populations were not taken into consideration. The authors note that the geographic coverage of identified studies was limited and that the findings are very dependent on the setting which limits generalizability.

### What Do these Findings Mean?

These findings suggest that PrEP could be a cost-effective tool to reduce new HIV infections in some settings. However, the cost-effectiveness of PrEP is dependent upon cost, the epidemic context, program coverage and prioritization strategies, participants' adherence to the drug regimen, and PrEP efficacy estimates. These findings will aid decision makers quantify and compare the reductions in HIV incidence that could be achieved by implementing a PrEP program.

Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001401.

### Introduction

Since the announcement of the results of HIV pre-exposure prophylaxis (PrEP) trials and the HPTN052 early treatment for prevention trial, there have been crucial policy discussions about the use of antiretroviral (ARV) drugs to prevent HIV acquisition or transmission. With regards to PrEP, encouraging results were first reported for men and transgender women who have sex with men in the iPrEX trial [1], which showed a 44% (95% CI 15–63) reduction in HIV acquisition with a daily dose of tenofovir/emtricitabine (TDF/FTC). In two large trials, the Partners PrEP [2] and TDF2 [3] studies, PrEP was found to be effective in reducing the risk of heterosexual HIV transmission using either TDF or TDF/FTC daily (Partners PrEP) and TDF/FTC daily (TDF2). However, FEM-PrEP [4], a trial recruiting heterosexual women in South Africa, Tanzania, and Kenya for daily TDF/FTC was closed prematurely in 2011 for futility as was the oral TDF arm of the VOICE trial [5] in women in South Africa, Uganda, and Zimbabwe. Two topical PrEP trials have tested the efficacy of 1% TDF gel and a third, FACTS001 [6], is currently recruiting women in South Africa. The CAPRISA 004 trial [7] in Kwa Zulu-Natal found that pre- and post-coital vaginal TDF gel reduced women's acquisition risk by 39% (95% CI 6–60) but the VOICE trial stopped its gel arm when it became evident that daily gel use was safe but not effective [8].

Clinical guidance on oral PrEP has already been offered by the US Centers for Disease Control and Prevention, the Southern African HIV Clinicians Society, World Health Organization (WHO), and the British Association for Sexual Health and HIV [9][13]. An advisory panel to the US Food and Drug Administration recently recommended oral TDF/FTC for preventive use among people at higher risk of HIV exposure [14]. As PrEP emerges as an option for inclusion in the HIV prevention toolbox, it is important for national policy and decision makers to identify where PrEP may fit best within already established HIV prevention programming (and budgets) and the potential implications of introducing such policy changes. In particular, decision makers need information translating the trial results into potential population-level impact and cost-effectiveness to ensure that any additional investment will have the maximum possible effect on the epidemic.

Economic and mathematical models provide a framework to integrate information on efficacy, effectiveness, costs, and patient outcomes to support decision making and resource allocation [15]. However, due to their complexity, dependence on assumptions made, and inherent uncertainties, generalising results from these models can be difficult. In this review, we aim to assess published cost-effectiveness models that have evaluated the expected health gains and costs of PrEP interventions. Specifically, our objectives are: (1) to describe modelling approaches of cost-effectiveness analyses of PrEP; (2) to compare the effects of epidemiological and cost assumptions on cost-effectiveness results; and (3) to explore the potential impact on cost-effectiveness estimates of five issues raised by policy makers [16][18] when considering PrEP implementation: prioritisation, adherence, behaviour change, toxicity, and resistance.

### Methods

We performed a systematic review of the published literature following the protocol available in Text S2 and adhering to the PRISMA guidelines for reporting of systematic reviews (Text S1: PRISMA checklist) [19] and guidelines for appraisal of economic evaluations [20].

#### Search Strategy, Inclusion Criteria, and Study Selection

A broad strategy using both MeSH headings and free text, with no language limitations, was used to search PubMed/Medline, ISI Web of Knowledge (including Web of Science, Current Contents Connect, Derwent Innovations Index, CABI: CAB Abstracts, and Journal Citation Reports), Centre for Reviews and Dissemination databases (including DARE - Database of Abstracts of Reviews of Effects, NHS EED - NHS Economic Evaluation Database, and HTA database - health technology assessments), EconLIT, and region-specific databases (African Index Medicus, Eastern Mediterranean Literature (WHO), Index Medicus for South-East Asia Region, LILACS for Latin America). Our searches covered all published research up to the last search performed 14 January 2013 with no limitations on publication date. The following keywords were used: “cost” AND “tenofovir OR pre-exposure prophylaxis OR chemoprophylaxis OR PrEP” AND “HIV.” Citations and bibliographies of full text reports retrieved were reviewed for additional relevant articles. Abstracts from international conferences identified in the searches were also reviewed, as was the website of the International AIDS Economic Network. Experts were consulted for additional studies. We included all modelling studies reporting both cost and impact of a potential roll-out of a PrEP programme. We excluded those studies where costs were not assessed. No restrictions were made on the type of model, geography, mode of transmission, or impact (effectiveness) metric chosen. We included studies looking at both topical and systemic PrEP products. Full published papers were eligible, as well as abstracts from conferences providing sufficient information. Two authors (GBG and AB) screened titles and abstracts to identify potentially relevant articles. Full text reports of these articles were assessed independently for inclusion.

Data were extracted from selected studies by one reviewer (GBG) into prepared data sheets and independently cross-checked by a second assessor (AB). For conference abstracts selected for inclusion, we contacted the first author listed for further information. Extracted information on the study design included the type of study, viewpoint of analysis, timeframe, setting and population, background HIV prevalence or incidence, mode of HIV transmission, and a detailed description of alternative programmes compared in the studies (baseline scenario and PrEP scenario). We also tabulated data on the impact including risk heterogeneity, efficacy or effectiveness of PrEP, adherence (to programme or individual), behavioural change expected after introduction of PrEP, resistance, toxicity due to PrEP use, and disability-adjusted life year (DALY)/quality-adjusted life year (QALY) assumptions. A description of economic assumptions includes expected drug cost, other service costs, costs above service level, downstream antiretroviral treatment (ART) costs averted, discount rates, and, finally, cost-effectiveness results by metric and the conclusions presented in each publication. Prioritised scenarios were defined as those scenarios where PrEP was offered to specific sub-populations within the population modelled. While providing a critical assessment and narrative review of the studies included, we did not attempt to perform a meta-analysis due to the variability across the studies in reporting outcomes. Therefore, we adjusted estimates of cost-effectiveness for inflation to US$2012 to be able to compare studies from different years [21]. For those studies reporting cost/DALY averted, cost/QALY averted, or cost/life-year saved (LYS), we compared the estimates to a benchmark for cost-effectiveness [22] of one times the gross domestic product per capita (GDP/capita) per DALY averted, per QALY gained, or per LYS, depending on the unit of outcome used by each study. While DALYs, QALYs, and LYS are not equivalent, and decision rules vary by setting, this gives a broad indication of potential cost-effectiveness. The values for current GDP/capita were sourced from the World Bank databank for each country [23]. There is much controversy around decision rules [24], and while the comparison against GDP is the conventional approach, it should be noted that this may not represent the true opportunity cost in countries where less cost-effective health interventions are not being implemented at scale. ### Results We screened 961 titles and abstracts retrieved from 14 electronic databases. After performing web searches and consulting experts in the field, 36 full text articles were evaluated. We also reviewed the reference lists and citations of these articles. Of these 36, 13 studies were included in the review [25][37]: 11 peer-reviewed publications and two peer-reviewed conference abstracts (Figure 1). Articles excluded are listed in Table S1 and a summary of conclusions of the articles included are presented in Table S2. We present in Tables 1 to 4 the data extracted from the studies reviewed by study design, description of alternative programmes compared, impact, and cost assumptions. All studies were published between 2007 and 2013 and modelled the impact and cost, from a health care provider perspective, of PrEP scale-up in diverse settings. These settings included: heterosexual transmission in generalised epidemics in sub-Saharan Africa—the Southern Africa region [25], South Africa [28],[30],[31],[32],[36],[37]), and other modes of transmission in concentrated epidemics—among people who inject drugs (PWID) in Ukraine [33]; and men who have sex with men (MSM) in the USA [26],[29],[34],[35] and in Peru [27]. Timeframes varied from 5 to 20 y. All studies focused the models on high prevalence/incidence populations (Table 1). In all models, the comparison scenario did not include PrEP and assumptions varied regarding current treatment scale-up: from no ART programme included [25],[26],[32] to ART coverage remaining stable at a current level [27],[29],[31],[34],[35] or an ongoing ART programme coverage expansion [28],[30],[33],[36],[37]. While most of the studies looked at systemic PrEP (daily oral dosing), two studies in South Africa looked at vaginal gels [31],[32]. Coverage assumptions were stated as scenarios. The criteria used to characterise priority populations varied among the studies, including high risk of acquisition (defined by sexual activity, condom use, or HIV incidence) [25][27],[35],[37], age [25],[30],[31],[34],[36], and timing of PrEP use [28] in relation to users' life events (Table 2). All models were transmission models, except for two Markov simulations [31],[34]. Efficacy and effectiveness estimates varied from estimated ranges that were assumed prior to the results from clinical trials and had wide ranges (from 10% to 90%) [25],[26],[30],[33],[34] to estimates available directly from clinical trials [27][29],[31],[32],[35][37]. Several authors interpreted effectiveness as being dependent on the product efficacy and the individual-level adherence, specifically modelling this interaction [25][29],[32],[36]. Adherence assumptions varied from random [25] to profiles based on observations from published trials [27][29],[32]. Potential behaviour change following the introduction of a PrEP programme was included in the models as an increase in the number of sexual partners [25],[26], changes in condom use [27],[30], or both [35]. Drug resistance associated with PrEP use was explicitly modelled in one study [25], while in two further studies it was represented as a decrease in the rate of virologic suppression while on subsequent treatment [31],[34]. The studies did not assume any reduction in the quality of life or disability weights due to PrEP use, with the exception of three studies where toxicity to PrEP was addressed through a reduction in the quality of life and/or an excess fatality rate among PrEP users (Table 3) [31],[34],[35]. The majority of studies presented costs for PrEP programmes including drugs and monitoring costs, except for two studies that included drug costs only [25],[32]. Costs above service level were only included in two studies, as overheads [31] or a mark-up percentage of 5% [27]. Overall PrEP programme costs were consistent among studies by setting and ranged from high in the USA (between US$8,000 and US$12,000 per person-year) to low in South Africa (between US$80 to US$250). All cost estimates were driven by the cost of drugs. Three studies in the USA [26],[29],[35] and six in South Africa [28],[30][32],[36],[37] included averted ART costs. Ranges of estimated cost of ART were consistent among studies and context-specific (<US$1,000 per person-year in South Africa to >US$15,000 per person-year in the USA) (Table 4). We present all cost-effectiveness estimates in Table 5 by epidemiological context and scenario modelled. #### Generalised Epidemics in Southern Africa (n = 7) Studies on topical PrEP and two studies on oral PrEP suggest the intervention to be cost-effective (topical PrEP: <200 US$/DALY [32], <3,000 US$/LYS [31]; oral PrEP: <5,000 US$/QALY [28], <2,800 US$/QALY [37]) using benchmarks for cost-effectiveness specific to South Africa [22]. Three studies reported cost/infection averted only, estimates ranging from US$1,000 to 39,900 [25],[30],[36].

For topical PrEP, the two studies presented different estimates of cost-effectiveness: less cost-effective in Walensky et al. [31] (<US$1,600–US$2,700/life year saved) than in Williams et al. [32] (<US$18–US$181/DALY averted) due to a more comprehensive set of assumptions in the former (i.e., inclusion of the above service level costs of providing PrEP, adverse outcomes, topical PrEP toxicity, and resistance as well as a lifelong use of PrEP and discounting) [31],[32]. Prioritisation to high-risk key populations (high incidence groups, such as young women in South Africa) and improvements in adherence maximised the effectiveness of a topical PrEP programme [31],[32].

For oral PrEP, the impact was estimated to be higher if PrEP was prioritised for use among people at higher risk of HIV acquisition compared to no prioritisation strategy in four of the five studies included (i.e., higher sexual activity groups in Abbas et al. [25], couples at higher risk in Hallett et al. [28], people with high number of partners and low condom use in Alistar et al. [37], and younger women in Pretorius et al. [30]). In Cremin et al. [36], the authors compared PrEP prioritised to 15 to 24 years old to no prioritisation (PrEP available to the total adult population: 15 to 54 years old) and found the impact of the two strategies was very similar. However, the group prioritised (15 to 24 years old) did not present the highest risk of infection in this population. The impact of prioritising by age may be more evident when the intervention is aimed at age groups where incidence peaks (in this case among the 25- to 34-year age group).

Four studies analysed the interactions between oral PrEP and an expanding ART programme. Pretorius et al. found oral PrEP cost-effectiveness and its impact at population level to be considerably reduced if PrEP is added to the expanding ART programme [30]. Accordingly, Alistar et al. and Cremin et al. found that expanding ART coverage in this setting will be the more attractive strategy than investing in oral PrEP [36],[37]. However, Alistar et al. found PrEP to be cost saving, when delivered to individuals at greater risk of infection with no ART expansion [37]. Cremin et al. [36] found that a PrEP intervention was not cost-saving when implemented on top of a base case that included an 80% coverage of ART for people with CD4 counts of less than 200 cells/ml and male circumcision to be scaled up to 80%. Hallett et al. compared early ART to PrEP in HIV-serodiscordant couples, finding that if higher risk couples change their behaviour (for example through risk reduction counselling), earlier initiation of ART might become a cost-effective alternative to oral PrEP [28]. Assumptions about behavioural change (an increase in the number of partners) was a key driver of cost-effectiveness in Abbas et al. [25], while Pretorius et al. [30] found a lesser impact on cost-effectiveness following changes in condom use. This might be explained by the inclusion in Pretorius et al. of a background decrease in condom use with age, with older women tending to have less condom use. Hallett et al. did not include changes in behaviour due to oral PrEP introduction in their analyses. Resistance and toxicity levels did not significantly affect cost-effectiveness estimates [25],[31].

#### Concentrated Epidemics among People Who Inject Drugs in Ukraine (n = 1)

Alistar et al. [33] found PrEP not to be a cost-effective intervention in isolation from other HIV control interventions for use among populations of PWID (US$14,590–US$14,680/QALY gained) using benchmarks for cost-effectiveness specific to Ukraine [22]. PrEP is considerably less attractive when compared to the expansion of either methadone maintenance therapy (US$530/QALY gained) or to the combination of methadone maintenance therapy and ART for those in need (US$870/QALY gained) [33].

### Discussion

This systematic review included 13 modelling studies estimating the cost and potential population-level impact of introducing a PrEP programme in generalised and concentrated epidemic settings. Our findings show that PrEP is estimated to have the potential to be a cost-effective addition to HIV prevention programmes in some settings. However, the cost-effectiveness of PrEP is likely to depend on considerations such as cost, the epidemic context, PrEP programme coverage and prioritisation strategies, as well as individual adherence levels and PrEP efficacy estimates.

To prevent heterosexual transmission in the generalised epidemics of southern Africa, PrEP is potentially a cost-effective intervention. Topical PrEP, in particular, could have a significant impact in South Africa, providing a much-needed female-initiated prevention option. However, it should be noted that funding PrEP while other potentially more cost-effective HIV prevention interventions remain under-funded may have high opportunity costs. In concentrated epidemics, such as MSM-driven epidemics both in Peru and in the USA, PrEP could have a substantial impact on the epidemic but may not be affordable at current drug prices. In Ukraine, expansion of ART coverage and methadone maintenance treatment programmes for PWID should be a first priority, with PrEP potentially added on within a combination prevention framework. However, evidence to date shows PrEP might not be cost-effective in this setting at current drug prices. Nevertheless, findings from the phase III Bangkok Tenofovir Study of PrEP among PWID will shed light on the efficacy estimates of PrEP in this population and inform future model estimates in similar epidemic contexts [38].

In all settings, the price of drugs is a limiting factor in terms of affordability of PrEP programmes as has been previously suggested [39],[40], and is key to determining cost-effectiveness. Moreover, the findings above predominately exclude important service and above service costs of providing PrEP (i.e., regular HIV testing and blood chemistry panels; the costs of possible adverse outcomes, including PrEP-related toxicity and potential drug resistance attributable to PrEP; and system-wide costs of implementing a PrEP programme). All of these should be considered to improve the validity and utility of estimates. Another key limitation among the studies is that the majority did not include savings in treatment and hospitalisation due to secondary infections averted. Although carrying significant uncertainties, the inclusion of these benefits allows a more informed consideration of potential PrEP benefits within broader programmatic planning for HIV prevention and care.

In the models reviewed, several prioritisation strategies were explored. Prioritisation by sexual activity characteristics to deliver PrEP to those populations at highest risk of HIV exposure improved the cost-effectiveness estimates. However, the extent to which prioritising populations at higher risk improves cost-effectiveness results in the models depends largely on the assumptions made about sexual mixing and risk heterogeneity. Extra costs related to the identification and engagement of priority populations were not included in any of the studies, neither were considerations in terms of economies of scale. Furthermore, as results from the enrolment phase of iPrEX Ole show (65% of trial participants decided to continue taking PrEP), not all individuals at higher risk are willing to use PrEP [41]. Identifying and meaningfully engaging those at highest risk in tailored HIV prevention strategies represents a significant challenge for decision makers, health care providers, and prevention advocates.

Prioritisation by age was a strategy advanced in several studies. In the studies reviewed, prioritisation by age group resulted in a lower cost-effectiveness benefit compared to prioritisation strategies based on self-reported risk behaviour [25],[30],[31],[34]. However, the former has the advantage of being straightforward to implement compared to a selection of potential PrEP users based on self-reported risk behaviour. In contexts such as South Africa and the USA, age prioritisation clearly would focus on those populations at higher risk of HIV acquisition. Another prioritisation strategy analysed in one study was the delivery of PrEP depending on the stage in users' lives. In reality, PrEP use will not need to be sustained throughout an individual's lifetime but may vary as his or her risk situation changes over time. People may opt to use PrEP during specific higher risk life periods, such as during periods of active sex work or when serodiscordant couples are trying to conceive a child [42],[43]. Understanding potential scenarios of PrEP use over the life cycle is essential for decision makers to be able to evaluate the possible impact of PrEP programmes in their local contexts. An additional consideration concerns intermittent PrEP. The first report of safety and adherence to an intermittent PrEP regimen in Kenya showed that among MSM and female sex workers adherence was lower than for daily dosing [44]. Results from two phase II trials underway in France [45] and the USA [46] will help inform adherence requirements and, should intermittent pre- and post-exposure dosing be proven effective, help tailor PrEP programmes to consumer demand [47].

Behavioural change due to PrEP use and adherence to PrEP were estimated to have potentially significant impacts on programme effectiveness. While the emergence of drug resistance due to PrEP programme scale-up and PrEP-related toxicity assumptions did not significantly affect cost-effectiveness estimates, improvement of drug resistance surveillance systems as well as effective adherence counselling will be essential components of PrEP programme implementation, in addition to behavioural counselling.

This review has several limitations. The geographical coverage of the studies reviewed is partial and both the impact and cost evaluations are highly setting-specific, limiting the generalisability of the findings. We were unable to perform a meta-analysis due to the variability across studies in reporting outcomes. Nevertheless, in order to compare cost-effectiveness estimates across settings, we used the thresholds proposed by the WHO-CHOICE Project and the Commission on Macroeconomics as a benchmark [22]. These standards are based on the GDP per capita, assuming that a society is willing to pay the equivalent of up to one GDP per capita (for highly cost-effective interventions) or between one and three times the GDP per capita (for a cost-effective intervention for a DALY averted, QALY saved, or LYS). This is a normative selection of cost-effectiveness thresholds, albeit regarded as useful from a decision analytic perspective [24].

It is worth noting that, with the exception of four studies in South Africa [28],[30],[36],[37], research comparing the potential trade-offs of earlier treatment for prevention versus PrEP remains an important gap in the literature that should be addressed, especially in concentrated epidemics. Cost-effectiveness studies that demonstrate where resources applied can have the greatest impact will help inform this complicated decision-making, but these are not the only considerations. The decision to include a PrEP option within the combination prevention package requires input from all strata of society. For instance, in contexts where universal access to ART for patients in need has not been achieved, PrEP programme planning processes will be challenged by concerns about social justice, equity, and affordability. This is in addition to the hurdles of overcoming the marginalisation, stigmatisation, and criminalisation of many of the populations that would most benefit from tailored HIV prevention programming that includes the choice of PrEP. Disentangling these issues will be critical for effective decision-making, as will the consideration of potential synergies between an expanded testing and treatment programme and a PrEP programme.

While the interest of donors for modelling studies that compare the cost-effectiveness of different HIV prevention methods is expected to increase [48], current evidence is already available to aid policy makers in assessing PrEP as a new prevention option. In this context, our review sheds light on the main considerations that decision makers need to address when judging the relevance of cost-effectiveness estimates of a potential PrEP programme and the potential gaps in the modelling evidence. Given that our review shows that setting and target population are critical drivers of cost-effectiveness, the next step is to conduct context-specific demonstration studies, including comprehensive cost analyses, of different prioritisation and adherence promotion strategies to ensure that the maximum benefit from the introduction of PrEP is realised within combination HIV prevention programmes.

### Supporting Information

Table S1.

List of publications reviewed for inclusion and excluded from the review.

doi:10.1371/journal.pmed.1001401.s001

(DOCX)

Table S2.

Summary of conclusions of articles included in the review.

doi:10.1371/journal.pmed.1001401.s002

(DOCX)

Text S1.

PRISMA checklist.

doi:10.1371/journal.pmed.1001401.s003

(DOCX)

Text S2.

Protocol for systematic review (version 2).

doi:10.1371/journal.pmed.1001401.s004

(PDF)

### Acknowledgments

The authors would like to thank Sabina Alistar for her assistance with providing additional information on her studies.

### Author Contributions

Conceived and designed the experiments: GBG CH. Performed the experiments: GBG AB. Analyzed the data: GBG AB KKC AW AV CH. Wrote the first draft of the manuscript: GBG. Contributed to the writing of the manuscript: GBG AB KKC AW AV CH. ICMJE criteria for authorship read and met: GBG AB KKC AW AV CH. Agree with manuscript results and conclusions: GBG AB KKC AW AV CH.

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## The Annals of Mathematical Statistics

### Some Asymptotic Results in a Model of Population Growth

Burton Singer

#### Abstract

Motivated by ecological and genetic phenomena, Karlin and McGregor [3] introduced the following model to describe the continued formation and growth of mutant biological populations. It is assumed that a new mutant population arises at each event time of a stochastic process (referred to as the input process) $\{v(t),t > 0\}$ whose state space is the non-negative integers. Each new mutant population begins its evolution with a fixed number of elements and evolves according to the laws of a continuous time Markov chain $\mathscr{P}$ with stationary transition probability function $P_{i,j}(t)\quad i,j = 0, 1, 2, \cdots; t \geqq 0.$ We assume that all populations evolve according to the same Markov Chain and independent of one another. In terms of this structure, the basic question which we consider in this work can be formulated in the following manner: (A) Given an input process $\{v(t),t > 0\}$ and the individual growing process $\mathscr{P}$, determine the asymptotic behavior as $t \rightarrow \infty$ of the mean and variance of $S(t) = \{$number of different sizes of mutant populations at time $t\}$ and determine the limit distribution as $t \rightarrow \infty$ of $S(t)$ appropriately normalized. $S(t)$ is a special functional of the vector process $N(t) = \{N_0(t), N_1(t), N_2(t), \cdots\}\quad t > 0$ where $N_k(t) = \text{number of mutant populations with exactly} k \text{members at time} t$ and may be interpreted as a measure of the fluctuations in population size. We have restricted our considerations to this special case because it serves as a model problem for more general situations and possesses all the subtle difficulties of the general case. The random variable $S(t)$ can also be identified as the number of distinct occupied states at time $t$ among all Markov Chains which have begun their evolution up to that time. In the subsequent discussion we will refer to $\{S(t), t > 0\}$ as the "occupied states" process generated by the input process $\{v(t),t > 0\}$ and the Markov Chain $\mathscr{P}$. Without loss of generality we identify the state 0 as the initial state of all evolving Markov Chains and $-1$ as an absorbing state if absorption is possible. In this paper we introduce "occupied states" processes generated by a class of null recurrent, transient, and absorbing barrier Birth and Death processes and a Poisson input process. The special feature of this class is that with the normalization $Y(t;u) = t^{-1} X(t^\alpha u),\quad\alpha > 0$ $(\{X(t), t > 0\}$ is the growing process $\mathscr{P}$), the process $Y(t;u)$ converges weakly in the Markov sense as $t \rightarrow \infty$ to a Bessel diffusion (see C. Stone [8]). The main idea (also applicable to more general growing processes $\mathscr{P}$ is that one requires local limit theorems, and under some circumstances, specification of the rate of convergence of the transition density of $Y(t;u)$ to the density of the limiting diffusion in order to prescribe exact asymptotic formulas for $ES(t)$ and $\operatorname{Var} S(t)$ and to prove a central limit theorem for $S(t)$. The results of this paper are in sharp contrast with the asymptotic formulas for $ES(t)$ and $\operatorname{Var} S(t)$ which appear in the companion paper [6], where the growing process $\mathscr{P}$ is a general positive recurrent Markov chain and the input process remains Poisson. Section 2 contains basic definitions, some intuitive discussion, and precise statements of the main results on asymptotic behavior of $ES(t)$ and $\operatorname{Var} S(t)$. In Section 3, we present detailed proofs of the theorems of Section 2, and we conclude with a central limit theorem for $S(t)$ in Section 4. The appendix contains some technical lemmas which are essential for asymptotic formulas that incorporate speed of convergence theorems.

#### Article information

Source
Ann. Math. Statist., Volume 41, Number 1 (1970), 115-132.

Dates
First available in Project Euclid: 27 April 2007

https://projecteuclid.org/euclid.aoms/1177697193

Digital Object Identifier
doi:10.1214/aoms/1177697193

Mathematical Reviews number (MathSciNet)
MR260046

Zentralblatt MATH identifier
0219.60068

JSTOR


text:
# Thread: [SOLVED] Integration by parts with a polynomial fraction inside?

1. ## [SOLVED] Integration by parts with a polynomial fraction inside?

Here is what I have so far:
$
\int ln(x^2+10x+16)~dx = xln(x^2+10x+16) - \int \frac {2x^2+10}{x^2+10x+16}~dx
$

I am stuck after this though...

2. long division of the polynomial

3. How would this divide out? We have not really covered long division inside an integral in class yet. I know it splits into two integrals though right?

4. $2 + \bigg(\frac{- 20x - 22}{x^2 +10x +16}\bigg)$

I would like to show you how to do the long divison but not sure how to display it on latex.

5. Originally Posted by redman223
Here is what I have so far:
$
\int ln(x^2+10x+16)~dx = x \ln(x^2+10x+16) - \int \frac {2x^2+10}{x^2+10x+16}~dx
$

I am stuck after this though...
$
=x \ln(x^2+10x+16) - \int \frac {2x^2+20+32-10x-22}{x^2+10x+16}~dx
$

$
=x \ln(x^2+10x+16) - \int \left(2-\frac {10x+22}{x^2+10x+16}\right)~dx
$

$=x \ln(x^2+10x+16) -2x + \int \frac {5(2x+10)-28} {x^2+10x+16} ~dx$

$=x \ln(x^2+10x+16) -2x +5 \ln(x^2+10x+16) -28 \int \frac {1} {(x+5)^2-3^2} ~dx$

$=x \ln(x^2+10x+16) -2x +5 \ln(x^2+10x+16) - \frac{28}{2\times 3} \ln \left( \frac {x+5+3} {x+5-3} \right)$

$=x \ln(x^2+10x+16) -2x +5 \ln(x^2+10x+16) - \frac{14}{3} \ln \left( \frac {x+8} {x+2} \right)$

6. there is a mistake in the first line written by redman: the numerator of the last integral should be $x(2x+10)$, not $2x^2+10$

then $\frac{2x^2+10x}{x^2+10x+16}=\frac{2(x^2+10x+16)-10x-32}{x^2+10x+16}$ and so on...

7. You could also use partial fractions or trig substitution, whatever you feel more comfortable with.

8. Originally Posted by redman223
Here is what I have so far:
$
\int ln(x^2+10x+16)~dx = xln(x^2+10x+16) - \int \frac {2x^2+10}{x^2+10x+16}~dx
$

I am stuck after this though...
actually, i'd approach it this way

$\int \ln (x^2 + 10x + 16)~dx = \int \ln [(x + 2)(x + 8)]~dx = \int \ln (x + 2) ~dx + \int \ln (x + 8)~dx$

Now in light of the fact that we know $\int \ln x ~dx = x \ln x - x + C$ (we can get this via integration by parts, but you really should know this by heart), each of those two integrals are really easy with a simple linear substitution

Haha, I just realized the date on this thing. really late, but it might help someone anyway....


text:
# GATE Questions & Answers of Routers and Routing Algorithms (Distance Vector, Link State)

## What is the Weightage of Routers and Routing Algorithms (Distance Vector, Link State) in GATE Exam?

Total 7 Questions have been asked from Routers and Routing Algorithms (Distance Vector, Link State) topic of Computer Networks subject in previous GATE papers. Average marks 1.71.

Consider the following statements about the routing Protocols, Routing Information protocol (RIP) and open shortest path First (OSPF) in an IPv4 network.

I. RIP uses distance vector routing

II. RIP packets are sent using UDP

III. OSPF packets are sent using TCP

IV. OSPF operation is based on link-state routing

Which of the statement above are CORRECT?

Assume that source S and destination D are connected through two intermediate routers labeled R. Determine how many times each packet has to visit the network layer and the data link layer during a transmission from S to D.

Consider a network with five nodes, N1 to N5, as shown below

The network uses a Distance Vector Routing Protocol.once the Route have stabilized, the distance vectors

at different nodes are as following
N1:(0,1, 7, 8, 4)
N2: (1, 0, 6, 7, 3)
N3: (7, 6, 0, 2, 6)
N4: (8,7, 2,0,4)
N5: (4, 3, 6, 4, 0)

Each distance vector is the distance of best known path at that instance to nodes, N1 to N5, where the distance to itself is 0. Also, all links are symmetric and the cost is identical in both directions. In each round, all nodes exchange their distance vectors with their respective neighbors. Then all nodes update the distance vectors. In between two rounds, any change in cost of a link will cause the two incident nodes to change only that entry in their distance vectors.

The cost of link N2-N3 reduces to 2 (in both directions). After the next round updates, what will be the new distance vector at node, N3?

Consider a network with five nodes, N1 to N5, as shown below

The network uses a Distance Vector Routing Protocol.once the Route have stabilized, the distance vectors

at different nodes are as following
N1:(0,1, 7, 8, 4)
N2: (1, 0, 6, 7, 3)
N3: (7, 6, 0, 2, 6)
N4: (8,7, 2,0,4)
N5: (4, 3, 6, 4, 0)

Each distance vector is the distance of best known path at that instance to nodes, N1 to N5, where the distance to itself is 0. Also, all links are symmetric and the cost is identical in both directions. In each round, all nodes exchange their distance vectors with their respective neighbors. Then all nodes update the distance vectors. In between two rounds, any change in cost of a link will cause the two incident nodes to change only that entry in their distance vectors.

The cost of link N2-N3 reduces to 2 (in both directions). After the next round updates, what will be the new distance vector at node, N3?

At the update in the previous question ,the link N1-N2 goes down. N2 will reflect this change immediately in its distance vector as cost, $\infty$. After the NEXROUND of update, what will be the cost to N1 in the distance vector of N3?

Consider a network with 6 routers R1 to R6 connected with links having weights as shown in the following diagram

All the routers use the distance vector based routing algorithm to update their routing tables. Each router starts with its routing table initialized to contain an entry for each neighbour with the weight of the respective connecting link. After all the routing tables stabilize, how many links in the network will never be used for carrying any data?

Consider a network with 6 routers R1 to R6 connected with links having weights as shown in the following diagram

All the routers use the distance vector based routing algorithm to update their routing tables. Each router starts with its routing table initialized to contain an entry for each neighbour with the weight of the respective connecting link. After all the routing tables stabilize, how many links in the network will never be used for carrying any data?

Suppose the weights of all unused links in the previous question are changed to 2 and the distance vector algorithm is used again until all routing tables stabilize. How many links will now remain unused?


text:
# Reference Page of Float Object only if Page isn't actual page

Is it possible to tell LaTeX only use \pageref if the referenced object isn't on actual page?

if \pageref{fig:hello_world} != self.page then
\pageref{fig:hello_world}
end

-
Do you know package varioref (and cleveref)? varioref adds \pageref into the reference, if the figure or table is more than one page away. –  Kurt Aug 30 '12 at 16:18

I think perhaps you might like the varioref and/or the cleveref packages

varioref

\documentclass{article}

\usepackage{varioref}

\begin{document}

\begin{itemize}
\item Here is a reference to Table \vref{tab:thispage}.
\item Here's a reference to Table \vref{tab:nextpage}.
\end{itemize}

\begin{table}[!htb]
\centering
\begin{tabular}{cc}
1 & 2
\end{tabular}
\caption{Table}
\label{tab:thispage}
\end{table}

\clearpage
\setcounter{page}{20}

\begin{table}[!htb]
\centering
\begin{tabular}{cc}
1 & 2
\end{tabular}
\caption{Table}
\label{tab:nextpage}
\end{table}
\end{document}

cleveref

\documentclass{article}

\usepackage{varioref}
\usepackage{cleveref}

% each of the following has two versions
%   \crefname{environmentname}{singular}{plural}, to be used mid-sentence
%   \Crefname{environmentname}{singular}{plural}, to be used at the beginning of a sentence

% standard environments
\crefname{table}{Table}{Tables}
\Crefname{table}{Table}{Tables}

\begin{document}

\begin{itemize}
\item Here is a reference to  \vref{tab:thispage}.
\item Here's a reference to \vref{tab:nextpage}.
\end{itemize}

\begin{table}[!htb]
\centering
\begin{tabular}{cc}
1 & 2
\end{tabular}
\caption{Table}
\label{tab:thispage}
\end{table}

\clearpage
\setcounter{page}{20}

\begin{table}[!htb]
\centering
\begin{tabular}{cc}
1 & 2
\end{tabular}
\caption{Table}
\label{tab:nextpage}
\end{table}
\end{document}

-

You can use the refcount package to get the page number of the reference. Then you can use the xifthen package to do a comparison of integer values. You can get the value of the current page with the \value{page} command. In the MWE below, you can comment or uncomment the \clearpage to demonstrate the difference in behavior.

\documentclass{article}
\usepackage{refcount}
\usepackage{xifthen}
\usepackage[demo]{graphicx}

\begin{document}
\begin{figure}
\caption{Testing}\label{fig:test}
\includegraphics[width=0.4\textwidth]{temp}
\end{figure}
%Uncomment the clearpage command to get the pageref to print
%\clearpage
\ifthenelse{\getpagerefnumber{fig:test}=\value{page}}{}{\pageref{fig:test}}

\end{document}

You could now simplify things by changing the pageref command, so that you could can use pageref like normal, but it would run your conditional code.

\documentclass{article}
\usepackage{refcount}
\usepackage{xifthen}
\usepackage[demo]{graphicx}

\let\originalPageref\pageref
\renewcommand{\pageref}[1]{\ifthenelse{\getpagerefnumber{#1}=\value{page}}{}{\originalPageref{#1}}}
\begin{document}
\begin{figure}
\caption{Testing}\label{fig:test}
\includegraphics[width=0.4\textwidth]{temp}
\end{figure}
%Uncomment the clearpage command to get the pageref to print
%\clearpage
\pageref{fig:test}

\end{document}

-


text: dc.creator Bulkin, Bernard J. en_US dc.date.accessioned 2006-06-15T13:46:33Z dc.date.available 2006-06-15T13:46:33Z dc.date.issued 1976 en_US dc.identifier 1976-RD-2 en_US dc.identifier.uri http://hdl.handle.net/1811/9697 dc.description Author Institution: Polytechnic Institute of New York en_US dc.description.abstract Despite extensive experimental and theoretical work, uncertainties about the approximate form of normal modes of vibrations of hydrocarbon chains in the CH stretching region persist. The experimental observations are complicated by the possibility of Fermi resonance with the overtone of $CH_{2}$ deformation vibrations. Recent work on the melting of hydrocarbon chains in phospholipids has led to a reexamination of these assignments. While force field calculations appear to show that there is only a very small amount of coupling between C-H stretching vibrations on adjacent carbons, the experimental results, when one includes both infrared and Raman spectra and when one further examines both all trans and trans-gauche segments for the same molecule, lead to a different conclusion. This is particularly true for the asymmetric $CH_{2}$ stretches, which are seen to extend from 2875 to $2930 cm^{-1}$. The conclusions will be substantiated through a series of infrared and Raman difference spectra. en_US dc.format.extent 122868 bytes dc.format.mimetype image/jpeg dc.language.iso English en_US dc.publisher Ohio State University en_US dc.title CONCERNING THE ASSIGNMENT OF METHYLENE STRETCHING VIBRATIONS IN HYDROCARBONS en_US dc.type article en_US


text:
# Bias variance tradeoff boosting (xgboost) vs random forest (randomized bagging) which to use when?

I was looking up differences between boosting an bagging and I see this quoted everywhere

If the classifier is unstable (high variance), then we should apply Bagging. If the classifier is stable and simple (high bias) then we should apply Boosting.

also

Breiman [1996a] showed that Bagging is effective on unstable'' learning algorithms where small changes in the training set result in large changes in predictions. Breiman [1996a] claimed that neural networks and decision trees are examples of unstable learning algorithms.check last lines

Aren't gbdt's the most preferred/recommended learners in xgboost ? Which is contradictory considering how decision trees are apparently unstable learners.


text:
# IQ Contest, Daily, Weekly & Monthly IQ & Mathematics Competitions

#### Question No 1

217 x 217 + 183 x 183 = ?

#### Select the correct answer

Solution!
By DMAS rule do multiplication first and add the answers of multiplication.
.

#### Question No 2

In farm there is 2 ducks,6 cats ,4 dogs . Each weight of duck 4 kg, cat 4 kg and dog 7 kg what is the average weight of all animals?

#### Select the correct answer

Solution!
={( number of ducks Ã— weight)+( number of dogs x weight)}/ total animals
= 5 kilogram is average weight of all animals.
.

#### Question No 3

What comes next in the series 2, 6, 18, 54....

#### Select the correct answer

Solution!
No explanation available for this question..

#### Question No 4

4, 9, 16, 25, 26, 36...
Which one is odd?

#### Select the correct answer

Solution!
All numbers are square except 27..

Find odd one out

#### Select the correct answer

Solution!
No explanation available for this question..

#### Question No 6

Peter is swimming at a speed of 20 Km/h along the flow of water. If the speed of water is 5 Km/h What is swimming speed of Peter against the flow of water?

#### Select the correct answer

Solution!
No explanation available for this question..

#### Question No 7

7, 11, ___, 17, 19, 23
Find missing number?

#### Select the correct answer

Solution!
All are prime numbers..

#### Question No 8

What is the 1/4 of 1/3 of 1/5 of 540.

#### Select the correct answer

Solution!
=1/4 x 1/3 x 1/5 x 540
=1/60 x 540
=9
.

#### Question No 9

Nail is to finger as hand is to

#### Select the correct answer

Solution!
No explanation available for this question..

#### Question No 10

The sum of how many terms of the series 6 + 12 + 18 + 24 + ... is 1800 ?

#### Select the correct answer

Solution!
This is an A.P. in which a = 6, d = 6 and Sn = 1800
Then, n/2[2a + (n - 1)d] = 1800
n/2[2 x 6 + (n - 1) x 6] = 1800
3n (n + 1) = 1800
n(n + 1) = 600
n2 + n - 600 = 0
n2 + 25n - 24n - 600 = 0
n(n + 25) - 24(n + 25) = 0
(n + 25)(n - 24) = 0
n = 24
Number of terms = 24.
.

#### Question No 11

The present age of lewis and Brown are in ratio 1:2. Three years from now, the ages will in ratio 3:5. Find the age of lewis after five years?

#### Select the correct answer

Solution!
Let's present age
Lewis =l
Brown=b
l/b=1:2
l-2b=0
After three years
l+3/b+3=3:5
5l-3b=6
l=6
b=12
After 5 years
l=11
b=17
.

#### Question No 12

21 fishes are in a pond. 9 of them died. Now how many fishes are there in pond?

#### Select the correct answer

Solution!
No explanation available for this question..

#### Question No 13

In following number series, two terms have been put within brackets. Choose the appropriate option
Choose the appropriate option 4, 7, (9), 10, 13, 15, (16), 19

#### Select the correct answer

Solution!
The correct sequence is is + 3, + 2, + 1, + 3, + 2, + 1, + 3.
Clearly, both the terms 9 and 16 are correct..

#### Question No 14

In a fort there is enough food sufficient for 1200 man 5 days how long the food would have last for if there would would have been thousand men.

#### Select the correct answer

Solution!
Let food will last for X days.
As men and days are inversely proportional to each other so
X/5=1200/1000
X=1.2*5=5
X=6
.

#### Question No 15

Which word means the same as distinct?

#### Select the correct answer

Solution!
If something is distinct it is distinguishable  or seperate..

#### Question No 16

Forty is to sixty as 2x is to

#### Select the correct answer

Solution!
No explanation available for this question..

#### Question No 17

Find the same relationship as Ocean:Water

#### Select the correct answer

Solution!
No explanation available for this question..

#### Question No 18

Ana is 5 years more than Jack. The sum of their ages is 29. Find the age of Jack.

#### Select the correct answer

Solution!
let's
Jack= X
Ana= 5 + x
so, X + 5+ X=29
X = 29
Ana = 17 and jack = 12
.

#### Question No 19

,XWV, TSR, PON, ___, HGF, DCB.
Find the missing.

#### Select the correct answer

Solution!
In reverse series skip 1 Alphabet after consecutive 3 Alphabets. .

#### Question No 20

3, 5, 66, 7, 9, 66, 12, 14, 66, 17....?
Find next pair?

#### Select the correct answer

Solution!
It is Alternative series with difference of 2 and
every 3rd position number is 66.
.

#### Question No 21

0, 3, 10, ??, 36, 55, 78...

#### Select the correct answer

Solution!
No explanation available for this question..

#### Question No 22

In a family, there are 6 member A, B, C, D, E and F. A and B are married couple, A being the male member, D is only son of C, who is brother of A. E is the sister of D. B is daughter in law of F,  whose husband has died How is F related to A?

#### Select the correct answer

Solution!
A is male and married to B. So, A is husband and B is a wife. C is brother of A. D is a son of C.E, who is sister of D will be  daughter of C. B is the daughter in law of F whose husband has died means F ia the mother of A. Clearly, F is mother of A..

#### Question No 23

water : ______ :: food : hunger

#### Select the correct answer

Solution!
No explanation available for this question..

#### Question No 24

In a Fort there is food sufficient for 1500 men for 10 days. For how many days food will be sufficient if men are decreased 1000?

#### Select the correct answer

Solution!
Let food be last For x days
As men and food are inversely proportional to each other
so,
X/10=1500/1000
X=15
.

#### Question No 25

A pattern has 4 blue Triangles to every 12 yellow Triangles. What is the ratio of blue Triangles to all triangles?

#### Select the correct answer

Solution!
Total Triangles: 4 + 12 =  16
Blue: total triangles
4:16
1:4
.

#### Question No 26

Price of an article increases from $40,000 to$48,000. What is the percentage increase?

#### Select the correct answer

Solution!
Increase in price=48000-40000=8000
% increase= (8000/48000)*100
=16%
.

#### Question No 27

Choose or find odd word Rose, Lotus, Marigold, Lily, Tulip

#### Select the correct answer

Solution!
Here, all except Lotus are flowers, which grow on land while lotus is a water flower. Hence, the answer is (b). .

#### Question No 28

Idioms and phrases.
Bear out

#### Select the correct answer

Solution!
Description is not available..

#### Question No 29

CAAA, EEEE, GIIII, ___ , KUUU.
Find missing?

#### Select the correct answer

Solution!
1st letter is the alphabetical series skip between each segment C, E, G, I, K with vowel order A, E, I ,O ,U.

#### Question No 30

Determine if the ratio 2:3 is equal to?

#### Select the correct answer

Solution!
2 x 3 : 3 x3
6 : 9
Only 6:9 is correct and equal to 2:3
.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30


text:
# 1,603 questions

Tagged
• x
1
view
no
no

## can't program nrf52832ciaa

can't program nrf52832ciaa

I can connect the core through segger commander

I can erase the chip after push the download bottom in the keil 5 ,and erase the chip

but I can't program , what's wrong ?

19
views
no
no

## how to write a functions(program) for transmitting and receiving data over uart using nrf 51822?

Hi, there i am using nrf51822 to communicate with quectel ec25 .i want to send AT commands over uart and receive some response from quectel.for eg. i am sending a "AT" command i should get "ok" response in return ... (more)

40
views
no
no

## MPU9250 is not showing output

i am working with mpu xx example given in nordic website. it seems code is working fine i.e. compiling and dumping into nrf52 DK, But not showing any output values.

i was trying to run nrf5-mpu-simple example but not ... (more)

25
views
no
no

## trouble getting started with nRF52-DK

I have an nRF5- DK and I'm following this tutorial. I loaded the softdevice, I can compile, I can load the flash, I can see the output in Termite, I can change the code to print different information to ... (more)

41
views
no
1

## Performing DFU with nRF Connect v1.8 Fails to Switch from App to Bootloader - Worked on 1.7.5

Since upgrading to nRF Connect on my IOS device the DFU won't reconnect to the BLE in the boot-loader after initiation from the application.

The device will migrate to the boot-loader and begin advertising but nRF connect doesn't ... (more)

25
views
no
no

## iot stack compile for nrf52822

Hi,

I get following error when i try to compile nRF5_IoT_SDK_v0.9.x for target nrf52822

compiling x509_csr.c... assembling arm_startup_nrf51.s... <command line>(13): error: A1517E: Unexpected operator equal to or equivalent to < compiling x509_crt.c... compiling system_nrf51.c ... (more)

37
views
1
vote
1

## how to set the RAM start sddress of app and bootloader

I am working on OTA DFU about nRF52810. My refernece project are ble_app_uart\pca10040\s132 and bootloader_secure_ble\pca10040 I find that the RAM start address between are different. This is the start RAM address of APP:

This is the start ... (more)

41
views
no
1

## Set RTC in nRF52832

My application is built using the nRF52832 device. The system must only be "active" between certain times (5am through to 9pm).

I am a newbie and have no idea how to set the RTC of the nRF52832. I could either ... (more)

68
views
no
1

## How can i interface MPU9250 with nRF52 DK

As i am new in embedded programming,I was trying to connect MPU 9250 with nRF52 DK by using given examples. now it is showing error

  #error "No MPU defined. Please define MPU in Target Options C/C++ Defines"

where ... (more)

51
views
no
1

## how to define gpio pins and generate pwm on gpio pins?

Hi There, i am new to nrf51822 and new to program this kind of controller.I searched over the website, I couldn't find a good introductory documentation for programming the nrf51822, specifically the nrf51-dk. i have two problems 1 ... (more)

44
views
no
1

## RTC function using sleep mode

Im working on 14.0 and s132 and work inside ble_uart code...i was add rtc inside that code sucsessfully but now.. when device goes to sleep so rtc interrupt handler function not calling stop... so, can i use rtc ... (more)

19
views
no
no

Hi everyone ! I'm working with nRF 52840. I've downloaded softDevice s140 using Keil. Afterwards, I selected the target to nRF52840_xxaa and then build the project of Heart Rate Application and tried to download the code, I get the ... (more)

18
views
no
no

## How to turn on Leds only for advertising time?

Hi, i am using SDK v8.0 and in main function, initialization like this err_code = bsp_init(BSP_INIT_LED | BSP_INIT_BUTTONS, APP_TIMER_TICKS(100, APP_TIMER_PRESCALER), button_event_handler);  and

in advertising_start function, calling function is err_code = bsp_indication_set(BSP_INDICATION_ADVERTISING); this is working. but i want like this ... (more)

25
views
no
1

## Where can i find nrf51822 firmware?

Anyone know how to put the nrf51822 firmware again? I made an update and deleted it from the kit. Where can I find it?

Thanks

49
views
no
1

## How to use 10040

Hello , ebery one Please let me have a question about PCA 10040.

When you connect a USB cable, it acts as a virtual drive and if you copy hex format (such as Hart rate monitor) by dragging and dropping to ... (more)

24
views
no
no

## Parsing Device_name

I have a number of nRF52832 beacons that advertise at a set interval. All the beacons have a "device_name" set as "ECO". My application scans for these beacons with the device_name == "ECO". When the application reads a beacon device_name of ... (more)

40
views
-1
1

## how to interface tcrt1000 optical sensor with nrf51822?

Hi ,there i have tcrt1000 optical sensor wants to interface with nrf51822 so can anybody provide me the tutorial on this things with a code... cheers, Abhijeet

45
views
no
1

## Has anyone used nf51 bluetooth with some app mobile?

Has anyone ever used nf51 bluetooth with the app inventor?

I have values coming out of the microcontroller terminal. I want to send them to a mobile application using the app inventor.

But I do not know how to do ... (more)

46
views
no
no

## Battery Power problem

I am using nRF52840 board. And I used keil and nrfjprog, both successfully flashed the hex file onto the board with USB connected. The example I used is ble_app_uart_c.

My program runs fine, but once I disconnected the USB cable ... (more)

39
views
1
vote
1

I have a app that stores some calibration information in flash (1 page at 0x7F000) When I booted now I noticed it has replaced it with "DEADCODE" following some hex number, what is this?

35
views
no
no

## Any one can help me with source code of mpu9250 and nrf52 DK

As i am new i don't know from where i have to start if anyone help me with this it would be a great help to me

34
views
1
vote
1

## Symbol multiply defined

Hey all,

I tried to build my project in the Keil µVision IDE. But everytime I get the same error and I can't figure out where the problem should be. I searched for the multiply defined symbols but I ... (more)

57
views
1
vote
1

Hi all,

I'd like to pass bootloader version (2bytes) from bootloader_util_reset function (bootloader) to the main of application. can help me to acheive that?

14
views
no
no

## Cannot open Source input file

I am a newbie to Nordic thingy and Keil. So please help me with this. I downloaded SDK and opened it in Keil. It asked for updating software packs update and it was done. When I tried to build the ... (more)

45
views
no
1

I am getting random data while using saadc example to reading analog voltage applied to pin on nrf52840. i want to read analog output from MQ135 gas sensor, I have applied the voltage output from sensor to P0.06 and ... (more)

116
views
2
4

Im using sdk 14.0 and s132 When i add flashwrite codes to my project which has bluetooth communication ,it does not work I wanna send data to flash and i wanna read/write it What is the simplest way ... (more)

39
views
no
1

## start and stop advertising packet of every 5 min?

hi, i want to advertise packet every interval of 5min. how can i start and stop advertise packet.

21
views
no
1

## RTC and nrf_timer2 with BLE SOFTDEVICE nRF51_SDK_8.0.0

hi, i want to use 2 timer in my application and BLE continuous advertising. i'm able to do with NRF_TIMER2 and BLE continuous advertising and it's working fine. but when i add RTC0 part in my code, it ... (more)

37
views
no
2

## nrf52832 Central-Peripheral Connection

Hello,

I am using ndk52 (nrf52832) as peripheral and central in my system. I did some changes on ble-app-uart example for both. Now i can send my packets continiously. I am trying to change it little bit more. I want ... (more)

24
views
1
vote
1

HI,

I am using nRF51822 by Keil compiler. I found if it was programmed with boot loader nrf51422_xxac_s130.hex

by nRFGo Studio.

Then if download user code by Keil, it cannot run anymore. But if upload a zipped user code ... (more)

#### Statistics

• Total users: 24904
• Latest user: Ardis Mackie
• Resolved questions: 10659
• Total questions: 26081

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Posted 2017-09-22 08:27:00 by Rose Martin
• ### Creating a Keil project for a Bluetooth Mesh example (Updated for 0.10.0)

Posted 2017-09-19 12:08:11 by Kristian Skordal
• ### Using millis() like in Arduino.

Posted 2017-09-18 11:58:04 by schef

## Recent questions

• ### can't program nrf52832ciaa

Posted 2017-10-17 18:34:31 by luckxiaoer
• ### nRF52840 and others " printf()"

Posted 2017-10-17 18:30:44 by ToasTer86
• ### Help with breakpoints on Eclipse with sdk14 please

Posted 2017-10-17 18:18:00 by Tony
• ### Maximum power consumption

Posted 2017-10-17 18:15:05 by Ruediger
• ### Advertising restart after a disconnect event

Posted 2017-10-17 18:14:18 by Yatekii