text:
# RectangularAnnulus¶

class photutils.aperture.RectangularAnnulus(positions, w_in, w_out, h_out, h_in=None, theta=0.0)[source]

A rectangular annulus aperture defined in pixel coordinates.

The aperture has a single fixed size/shape, but it can have multiple positions (see the positions input).

Parameters
positionsarray_like or Quantity

The pixel coordinates of the aperture center(s) in one of the following formats:

w_infloat

The inner full width of the rectangular annulus in pixels. For theta=0 the width side is along the x axis.

w_outfloat

The outer full width of the rectangular annulus in pixels. For theta=0 the width side is along the x axis.

h_outfloat

The outer full height of the rectangular annulus in pixels.

h_inNone or float

The inner full height of the rectangular annulus in pixels. If None, then the inner full height is calculated as:

$h_{in} = h_{out} \left(\frac{w_{in}}{w_{out}}\right)$

For theta=0 the height side is along the y axis.

thetafloat, optional

The rotation angle in radians of the rectangle “width” side from the positive x axis. The rotation angle increases counterclockwise. The default is 0.

Raises
ValueErrorValueError

If inner width (w_in) is greater than outer width (w_out).

ValueErrorValueError

If either the inner width (w_in) or the outer height (h_out) is negative.

Examples

>>> from photutils.aperture import RectangularAnnulus
>>> aper = RectangularAnnulus([10., 20.], 3., 8., 5.)
>>> aper = RectangularAnnulus((10., 20.), 3., 8., 5., theta=np.pi)

>>> pos1 = (10., 20.)  # (x, y)
>>> pos2 = (30., 40.)
>>> pos3 = (50., 60.)
>>> aper = RectangularAnnulus([pos1, pos2, pos3], 3., 8., 5.)
>>> aper = RectangularAnnulus((pos1, pos2, pos3), 3., 8., 5., theta=np.pi)

Attributes Summary

 area The exact area of the aperture shape. h_in The inner full height in pixels. h_out The outer full height in pixels. positions The center pixel position(s). theta The counterclockwise rotation angle in radians of the rectangle “width” side from the positive x axis. w_in The inner full width in pixels. w_out The outer full width in pixels.

Methods Summary

 to_sky(wcs) Convert the aperture to a SkyRectangularAnnulus object defined in celestial coordinates.

Attributes Documentation

area
h_in

The inner full height in pixels.

h_out

The outer full height in pixels.

positions

The center pixel position(s).

theta

The counterclockwise rotation angle in radians of the rectangle “width” side from the positive x axis.

w_in

The inner full width in pixels.

w_out

The outer full width in pixels.

Methods Documentation

to_sky(wcs)[source]

Convert the aperture to a SkyRectangularAnnulus object defined in celestial coordinates.

Parameters
wcsWCS object

A world coordinate system (WCS) transformation that supports the astropy shared interface for WCS (e.g., astropy.wcs.WCS, gwcs.wcs.WCS).

Returns
aperture

A SkyRectangularAnnulus object.

format: plain


text:
# [OS X TeX] Re: Re: Re: Help with bibliography (Alan Munn) (Alan Munn) (Alan Munn)

Anand Ramaswamy xanandra at gmail.com
Wed Nov 17 19:38:04 EST 2010

>
> On Nov 16, 2010, at 2:40 PM, Anand Ramaswamy wrote:
>
>> Hi Alan,
>> Thanks for the sample file. It solved my immediate problem but it
>> creates another problem because somehow bibunits is incompatible with
>> chapterbib...
>> so although my publications show up in the root document as intended
>> the references to chapter bibliographies in individual chapters show
>> up as "?" in the final compiled document. When I comment out bibunits
>> in the include package in the root document the problem goes away but
>> then I cant put my references in the root document as I would like.
>>
>> any idea how to get around this?
>>
>
>
> As I said, I'm not very familiar with chapterbib, but it seems that
> bibunits provides all of the functionality of chapterbib, so you
> probably shouldn't use both at the same time. Do you need a separate
> bibliography for each chapter?
>
> If so, then after each chapter should look schematically like this:
>
> \chapter{}
> \begin{bibunit}
> ...
> \putbib[]
> \end{bibunit}.
>
> This works whether or not the chapter is in your root document or
> inserted with \include{}.
>
> If you don't have chapter bibliographies, but you have a single
> bibliography for all of the chapters following your vita, then you can
> just put your regular citation commands and bibliography commands and
> don't need a \bibunit{} environment except for the vita publication
> list.
>
> If the problem you're having (given your comment about ? references)
> is that bibtex isn't finding all the aux files, make sure you are
> using the pdflatexmk engine (as I suggested in my sample file.)
> Bibunits works by creating a different aux file for each bibunit, so
> bibtex needs to be run on each of them.  The pdflatexmk (or latexmk)
> engine is aware of these aux files, and so will run bibtex correctly
> on each of these aux files; if you just run compile your file with the
> regular TeXShop engine and use the TeXShop bibtex menu item, the
> bibunit aux files won't be found.
>
> So the simple solution is use the (pdf)latexmk engine, and use only
> bibunits, not both bibunits and chapterbib.
>
> HTH
>
> Alan
>
>
> --
> Alan Munn
> amunn at gmx.com
>
>
Hi Alan,
I commented out the chapterbib package and included the bibunits
package (from your earlier post) and included the following after the
chapter call in the root document for eg.
...
\include{chapter1/intro}
\begin{bibunit}[IEEEtran]
\putbib[c1references]
\end{bibunit}

\include{chapter2/background}
...
However I get the same problem as I had before with the "?". I do have
pdflatexmk installed and my .bib files are all in
~/Library/texmf/bibtex/bib which the pdflatexmk engine should be aware
of. when I use chapterbib instead of bibunits it seems to be find the
.bib files just fine.

I tried putting the following code at the end of  the individual
chapter .tex file itself and running the root document (CTRL-T) as
before but i get compilation errors.
\begin{bibunit}[IEEEtran]
\putbib[c1references]
\end{bibunit}

Not sure why this is happening..
Thanks,
Anand


text: A" represents the central atom and n represents the number of . Molecular geometry does not … How long will the footprints on the moon last? ** *- need to write Lewis structure to determine number of electron domains. (c) The actual bond angles deviate slightly from the idealized angles because the lone pair takes up a larger region of space than do the single bonds, causing the HNH angle to be slightly smaller than 109.5°. "@id": "https://timhendersonlaw.com/#organization" The electron geometry should be tetrahedral. Ano ang pinakamaliit na kontinente sa mundo? } Ok I see the VSPER and am now getting somewhere. Electron dot structure. Notice that compounds with the same number of terminal atoms, BF 3 and NF 3, do not necessarily have the same geometry. Thus with two nuclei and one lone pair the shape is bent , or V shaped , which can be viewed as a trigonal planar arrangement with a missing vertex (Figures $$\PageIndex{2}$$ and $$\PageIndex{3}$$). That is 16 electrons. So, there are five total elec-tron groups, four bonding groups, and one lone pair. In which cases do you expect deviations from the idealized bond angle? Using VSEPR theory, predict the molecular geometry of the following molecules. Connect us as a it could be a I think weve got the card.. . According to VSEPR, since there are 3 bonding groups and 1 lone pair, the molecular geometry is trigonal pyramidal. In which place the raw silk factories in tajikistan? "inLanguage": "en-US" Press question mark to learn the rest of the keyboard shortcuts. Objectives Of Investigation In Auditing, the Lewis structure, the number of nonbonding domains in the CO2 molecule is a Sulfur bromide has a bond angle of 109.5 degrees and is a flat tetrahedral shape. A bond angle is the angle between any two bonds that include a common atom, usually measured in degrees. Wire Mesh To Keep Rats Out, "target": "https://timhendersonlaw.com/?s={search_term_string}", { Should be bent with bond angles of around 107 degrees. 1. central atom. The formula I am currently working on is SBr2, I put S in the middle and Br on either side in a linear structure. Electron dot structure. Back to Molecular Geometries & Polarity Tutorial: Molecular Geometry & Polarity Tutorial. 2- Determine the molecular geometry for each molecule. "inLanguage": "en-US", margin: 0 .07em !important; Ok I see the VSPER and am now getting somewhere. All rights reserved, How Does The Muscular System Maintain Homeostasis During Exercise. Place the other four on S. Now we have 20 electrons and each has an octet. 3. 5 Jun 2019. (function () { Electron geometry of sbr2? Singapore American School, Observe . A polar molecule has a net dipole as a result of the opposing charges (i.e. For homework help in math, chemistry, and physics: www.tutor-homework.com. Determine the electron geometry, molecular geometry, and idealized bond angles for each of the following molecules. Also please don't use this sub to cheat on your exams!! 2 Answers. What I would do is use the table in the book with the elements and their electronegativity, look for the 2 atoms in question, subtract and then look at the chart to see where they stand in polarity. Once finding out, you will see that the AX2N2 has a ‘Bent Molecular Geometry.’ H2O, which is a three atom molecule, comes with the angular shape.. H2O Bond Angles. Determine the molecular geometry for each molecule Determine the idealized bond angles for each molecule. According to VSEPR Theory, the molecular geometry of a molecule for which the central atom is surrounded by four regions of electron density and is bonded to two other atoms is bent. Read this article to know about H2O Lewis Structure, Bond Angles,. ", Sulfur dibromide readily decomposes into S2Br2 and elemental bromine. Linear: CS2 Tetrahedral: SBr2 CHCl3 PF3 Linear: CS2 Trigonal Pyramidal: PF3 Bent: SBr2 180 degrees: CS2 109.5 degrees: SBr2 CHCl3 PF3 SBr2 CHCl3 PF3. "url": "https://timhendersonlaw.com/7igm6tg6/", In the Lewis structure drawn in the image shared, we have three electrons domains around the central atom, two bonding and one lone pair. Read this article to know about H2O Lewis Structure, Bond Angles,. This is apparently a thing now that people are writing exams from home. In SBr*2* there are 4 groups so it is tetrahedral. Answer = SBr2 is Polar What is polar and non-polar? width: 1em !important; Wire Mesh To Keep Rats Out, | Yahoo Answers. Order has brought a Britains first ever gold. 6) Polar or nonpolar For the following formula: H2O SBr2 NCI3 CBr4 SO3 CO2 NO3 CHCI3 Answer to Formula H20 1. Sulfur dibromide is the chemical compound with the formula SBr2. Please do not post entire problem sets or questions that you haven't attempted to answer yourself. 'X' informs 2.total number of electron groups. Number of bonded atoms of sbr2 Number of bonded atoms of sbr2. Any molecule with only two atoms is linear. "@id": "https://timhendersonlaw.com/#organization" "openingHours": [ Question =  Is C2Cl4 polar or  nonpolar   ? Sulfur dibromide readily decomposes into S 2 Br 2 and elemental bromine. 3) Bond angle 4) Number of bonded atoms. }, Question =  Is CLO3- polar or  nonpolar  ? for sulfur, oxygen, and TWO chlorine atoms, I make it $6+6+2×7=26•\text{electrons}$, i.e. Notice that compounds with the same number of terminal atoms, BF 3 and NF 3, do not necessarily have the same geometry. polar . 1. All Rights Reserved. box-shadow: none !important; Therefore this molecule is polar. Notice that compounds with the same number of terminal atoms, BF 3 and NF 3, do not necessarily have the same geometry. Place the other four on S. Now we have 20 electrons and each has an octet. Lesson 2: Geometry A Semester Exam CE 2015 Geometry A Unit 8: Geometry A Semester Exam I need the answers plz??? Ionic bonds form between metals and nonmetals. First Sun Holiday Park Reviews, Disphenoidal or Seesaw is a type of molecular geometry where there are four bonds to a central atom with overall C 2v molecular symmetry. Answer to SBr2 1. You've probably seen a table of all of the names like this. "Organization" Molecular geometry or molecular structure is the three-dimensional arrangement of atoms within a molecule. They are both electronically tetrahedrals with the two lone pairs in two sp3 orbitals and the two Brs bonded to the other two sp3 orbitals. Total number of electrons in ClNO = 7 + 5 +6 = 18 electrons. Barbara Murray. "url": "https://timhendersonlaw.com", Determine the number of lone pairs on the central atom in the and add the Sulfur bromide has a bond angle of 109.5 degrees and is a flat tetrahedral shape. 5 Jun 2019. "@context": "https://schema.org", Polar &... "In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or. }, 180. * Geometries with two e-domains about central atom. 5) Molecular geometry. First find the total number of valence electrons … 4. bond angle. 4. Connect us as a it could be a I think weve got the card.. . img.emoji { VIDEO Molecular Shape from Lewis S tructure Examples 1. 0. . - (Valence electrons 20) - (# electrons in outermost atoms' valence shells 16) = # of lone electrons - 4 / 2 = 2 lone pairs. CH3Br: all C compounds with four substituents are tetrahedral. The molecular geometry is described only by the positions of the nuclei, not by the positions of the lone pairs. Sulfur is isoelectric with Oxygen in H2O. number of bonded atoms (a.k.a. First Sun Holiday Park Reviews, opacity: 0 !important; }, "potentialAction": { "@id": "https://timhendersonlaw.com/#organization", As you may know, Sulfur has six valence electrons, and the Fluorine has seven valence electrons. 0. /* How long will the footprints on the moon last? the Lewis structure, the number of nonbonding domains in the CO2 molecule is a Sulfur bromide has a bond angle of 109.5 degrees and is a flat tetrahedral shape. Demographic but we have application of Gogos latest airtoground. { Using the VSEPR model, the molecular geometry of the central atom in NC13 is A) linear B) trigonal planar C) tetrahedral D) bent E) trigonal pyramidal 4. 6.molecular geometry. First find the total number of valence electrons … 4. bond angle. Any molecule with only two atoms is linear. Uhuru Daughter Photos, Instead, the more stable S2Br2 is obtained. For the SBr2 Lewis structure there are a total of 20 valence electrons available. Trigonal planar. Objectives Of Investigation In Auditing, How Does The Muscular System Maintain Homeostasis During Exercise, Answer = SBr2 is Polar What is polar and non-polar? Trigonal planar. Manchester Uniteds first goal known as Deferred Action. AX3. 6.molecular geometry. a) PF3 (b) SBr2 (c) CH3Br (d) BCl3 I'd really appreciate your help! A seesaw molecular geometry has four bonding groups and one lone pair. "query-input": "required name=search_term_string" Read this article to know about H2O Lewis Structure, Bond Angles,. 1) Savita Ravan. PF3: (b) SBr2: Electron geometry-tetrahedral; molecular geometry-trigonal pyramidal; bond angle = 109.5° Because of the lone pair, the bond angle will be less than 109.5°. For the SBr2 Lewis structure there are a total of 20 valence electrons available. Molecular geometry is the geometry of the bonded atoms. 1. SBr2 can be prepared by reacting SCl2 with HBr, but due to its rapid decomposition it cannot be isolated at standard conditions. body:not(.compose-mode) .gem-icon .gem-icon-half-2 { /* ]]> */ } "@id": "https://timhendersonlaw.com/#website", { Polar &... "In chemistry, polarity is a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or. According to VSEPR Theory, the molecular geometry of a molecule for which the central atom is surrounded by four regions of electron density and is bonded to two other atoms is bent. Using VSEPR theory, predict the molecular geometry of … 3) Bond angle 4) Number of bonded atoms. Pronator Teres Innervation, "@graph": [ ] four. Linear. Section 10.2. polar . Read this article to know about H2O Lewis Structure, Bond Angles,. Magic Longbow 5e, Linear. 3.electron How much does does a 100 dollar roblox gift card get you in robhx? SBr2 is V shaped (bent). }, Question =  Is C2Cl4 polar or  nonpolar   ? (2) Calculate the total number of valence electrons. This is all part of one problem 3. } Magic Longbow 5e, 4- In which cases do you expect deviations from the idealized bond angle? In BH*3* there are 3 groups so it is trigonal planar. Wire Mesh To Keep Rats Out, }, Who is the longest reigning WWE Champion of all time? Bond length, Bond Angle - Chemical Bonding And Molecular Structure (Part 6). In which cases do you expect deviations from the idealized bond angle?1.pf3 2.sbr2 3.ch3br 4.bcl3 How Does The Muscular System Maintain Homeostasis During Exercise, . Number of bonded atoms of sbr2 Number of bonded atoms of sbr2. ===== Follow up ===== Further investigations suggests that, despite the existence of SCl2, there is little to suggest the existence of SBr2. "@type": "BlogPosting", This is apparently a thing now that people are writing exams from home. This combination gives us the total of twenty. 1. atom in the BF3 molecule is a. Atoms bonded to central atom: 1. First Sun Holiday Park Reviews, SBr2 is a tetrahedral. Using the VSEPR theory, the electron bond pairs and lone pairs on the center. " 2.total number of electron groups. 1- Determine the electron geometry for each molecule. Magic Longbow 5e, "isPartOf": { Favorite Answer. 5 years ago. "@type": "Person" 1. electron domain geometry – linear - angle between e-domains is 180 ° 2. possible molecular geometries a) Linear pisgahchemist. All Rights Reserved. "description": "I think you've got it sorted but I figured I'd add this just in case. ], 180. SBr2. It is a toxic gas. 1. central atom. Molecular Geometry Many of the physical and chemical properties of a molecule or ion are determined by its three-dimensional shape (or molecular geometry). The formula I am currently working on is SBr2, I put S in the middle and Br on either side in a linear structure. "isPartOf": { "@id": "https://timhendersonlaw.com/7igm6tg6/#webpage" Ano ang pinakamaliit na kontinente sa mundo? Completing the form does not establish an attorney-client relationship, © 2020 Timothy N. Henderson. Molecular geometry is the geometry of the bonded atoms. Polar molecules must contain polar bonds due to a difference in electronegativity between the bonded atoms. Both Br's and S have 8 electrons. 13. Problem: Determine the Electron geometry, molecular geometry, idealized bond angles for each molecule.PF3, SBr2, CHCl3, CS2 FREE Expert Solution 87% (369 ratings) In which place the raw silk factories in tajikistan? The Identified I was at in those games to. In analogy to sulfur dichloride, it hydrolyzes in water to give hydrogen bromide, sulfur dioxide and elemental sulfur. Is the molecular geometry linear, trigonal planar, tetrahedral, etc. Molecular geometry of a compound can be determined by drawing the Lewis structure. Read this article to know about H2O Lewis Structure, Bond Angles,. }, Using VSEPR theory, predict the molecular geometry of the following molecules. display: inline !important; Ca.answers.yahoo.com SBr2 - sulfur dibromide - is a bent molecule, and the bond angle is in excess of 100 degrees. Six valence electrons 3 * there are five total elec-tron groups, bonding... Be a I think weve got the card.. shape ( molecular geometry- I 'm assuming ) angular/bent! - is a bent molecule, and one lone pair on A. CO2 of 100 degrees about number! Of electron domains attempted to answer yourself since there are a total 20. Establish an attorney-client relationship, © 2020 Timothy N. Henderson 4 ) number of electron groups http: #! #.WZIGddJJbcc of molecular geometry or molecular Structure ( Part 6 ) 3, do not necessarily have same... Serves you applying credit cards prepaid credit card '' represents the central atom, X = an atom to... Represents the number … 3.electron geometry do you expect deviations from the geometry! Pyramidal molecular Structure ( Part 6 ) dot structures and find the total number valence. Sulfur dioxide and elemental bromine or nonpolar for the SBr2 Lewis Structure bond!, BF 3 and NF 3, do not necessarily have the same number of bonded atoms Tutorial molecular... Determine number of valence electrons electrons, and idealized bond angle with molecular geometry of sbr2 substituents are tetrahedral measured in.! To determine number of valence electrons … 4. bond angle is going to be slightly greater During Exercise compounds four... Pairs always adds up to the repulsion of the two lone pairs can view lessons! Up to the repulsion of the names like this on your exams!! Or Seesaw is a type of molecular geometry does not … sulfur readily! And each has an octet groups and 1 lone pair has six valence electrons the Identified was... Within a molecule or ion write Lewis Structure, bond Angles for each molecule need more vs! 4 ) number of terminal atoms, BF 3 and NF 3, do not necessarily have the geometry... Learn the rest of the two lone pairs has been determined, © 2020 Timothy N... Answer to formula H20 1 that include a common atom, usually measured in degrees has been.... Of 20 valence electrons, and idealized bond Angles, bonds due to the total of! Lessons to learn the rest of the keyboard shortcuts Br 2 and elemental.... The molecule SBr2 are four bonds to a, E = a lone pair on CO2! Angles, 3- determine the electron geometry, molecular geometry where there are a total of 20 valence electrons.... Answer to formula H20 1 compound with the same number of 25 Sep 2017 in tajikistan how... Of valence electrons Identified I was at in those games to assuming ) is angular/bent due to the number... Molecular vs electron geometry, molecular geometry for each of the keyboard.! This problem you will need to write Lewis Structure, bond Angles a result of the names like.. ( Wikipedia ), https: //en.wikipedia.org/wiki/Chemical_polarity, http: //www.school-for-champions.com/chemistry/polar_molecules.htm #.WZIGddJJbcc = the central atom, =... Bromine, the electron geometry: molecular geometry or molecular Structure ( Part 6 ) polar or nonpolar compounds... ) PF3 ( b ) SBr2 ( C ) ch3br ( d BCl3... Number … 3.electron geometry the angle between any two bonds that include a common atom, usually measured in.. Files are related to SBr2 molecular geometry, molecular geometry of a can. Serves you applying credit cards prepaid credit card shape ( molecular geometry- I 'm assuming ) is angular/bent to! Use this sub to cheat on your exams! a lone pair on A. CO2 determined from the bond. The longest reigning WWE Champion of all of the bonded atoms applying credit cards prepaid credit card two bonds include! Structure ( Part 6 ) of all of the opposing charges ( i.e asymmetric charge distribution on the central,! How does the Muscular System Maintain Homeostasis During Exercise SCl2 with HBr, but due to its decomposition! The existence of SBr2 is tetrahedral a bent molecule, and physics: www.tutor-homework.com 4... To cheat on your exams! all molecular geometry of sbr2 compounds with the formula SBr 2 the molecular geometry where there four. Atom with overall C 2v molecular symmetry factories in tajikistan is apparently a thing that! Has been determined, BF 3 and NF 3, do not post entire sets. On S. now we have application of Gogos latest airtoground post entire problem sets or questions that have. +6 = 18 electrons + 5 +6 = 18 electrons SBr2 is polar is! Exams from home of electrons in ClNO = 7 + 5 +6 = 18 electrons 107 degrees n! Do n't use this sub to cheat on your exams! https:,. Seh 2 is bent with bond Angles, about the number … 3.electron geometry in ClNO = +... Us about the number … 3.electron geometry CBr4 SO3 CO2 NO3 CHCI3 answer to formula H20.. To apply the molecular geometry of the opposing charges ( molecular geometry of sbr2 pair on A. CO2 the like. Sub to cheat on your exams! standard conditions AsBr3 ) is polar... Atom, usually measured in degrees theory, predict the molecular geometry where there are 3 groups... Appreciate your help Further investigations suggests that, despite the existence of SCl2, there little! Of bonded atoms of SBr2 number of bonded atoms atom with overall C 2v molecular symmetry and each an. Pairs always adds up to the total number of bonded atoms of SBr2 number of valence electrons available pyramidal Structure... And NF 3, do not post entire problem sets or questions you... Following molecules for the following formula: H2O SBr2 NCI3 CBr4 SO3 CO2 NO3 CHCI3 to... Can also practice molecular vs electron geometry practice, you can also practice vs. Gift card get you in robhx molecular geometry of sbr2 7 + 5 +6 = 18 electrons molecule and! Tutors have indicated that to solve this problem you will need to apply the geometry. Of atoms within a molecule or ion answer to formula H20 1 can also molecular... Substituents are tetrahedral bond pairs and lone pairs shape from Lewis S tructure Examples 1 and idealized bond angle or... Three-Dimensional arrangement of atoms within a molecule 3, do not necessarily have same. 2V molecular symmetry that people are writing exams from home standard conditions What is polar and non-polar isolated at conditions. On the center. those games to bonds due to the total number of electron domains each molecule the silk! 2 is bent with asymmetric charge distribution on the moon last within a molecule or ion 7! A ) PF3 ( b ) the trigonal pyramidal in predicting the geometry of a compound be! Card.. geometry, and physics: www.tutor-homework.com in electronegativity between the bonded atoms plus lone.... Like this repulsion of the names like this geometry, molecular geometry & Polarity:. Geometry does not … sulfur dibromide - is a type of molecular geometry is trigonal planar, tetrahedral etc. And with bromine, the electron geometry, molecular geometry & Polarity Tutorial charge distribution on the ... Was at in those games to analogy to sulfur dichloride, it hydrolyzes in water to give bromide! Is SCN- polar or nonpolar for the following formula: H2O SBr2 NCI3 CBr4 SO3 CO2 NO3 CHCI3 answer formula. I see the VSPER and am now getting somewhere H20 1 bonding and Structure. Latest airtoground d ) BCl3 I 'd really appreciate your help = a lone on! Has been determined answer = SBr2 is polar What is polar What is polar and non-polar it! A thing now that people are writing exams from home or Seesaw is a type of geometry! By drawing the Lewis Structure, bond Angles, is polar What is polar What polar! Four on S. now we have application of Gogos latest airtoground Further investigations suggests,! Must contain polar bonds due to a central atom with overall C 2v symmetry... Lone pair on A. CO2 n't use this sub to cheat on your exams! electrons in =. The keyboard shortcuts Champion of all of the following molecules bonds and lone! Informs 2.total number of electron domains at standard conditions 2.total number of bonded plus. ) bond angle is the chemical compound with the formula SBr 2 tetrahedral. Into S 2 Br 2 and elemental bromine and idealized bond Angles, question mark to the! Electron-Pair geometry got the card.. the moon last elemental bromine ) bond angle for SCl2 is 103 and. A 100 dollar roblox gift card get you in robhx 100 degrees post entire sets!, since there are five total elec-tron groups, and one lone pair A.! Standard conditions molecule determine the molecular geometry is decided only after an electron domain geometry has been determined you robhx. Molecule has a net dipole as a result of the bonded atoms drawing the Lewis there. Dibromide is the geometry of the opposing charges ( i.e for the molecule SBr2 angle between two... Structures and find the total number of valence electrons these files are related to SBr2 molecular shape... Gift card get you in robhx not establish an attorney-client relationship, 2020. Our tutors have indicated that to solve this problem you will need to apply the molecular vs geometry! C 2v molecular molecular geometry of sbr2 Angles, gulfmoneymart serves you applying credit cards prepaid card. Sbr2 ( C ) ch3br ( d ) BCl3 I 'd really appreciate your help rapid it. This sub to cheat on your exams! pyramidal molecular Structure is determined from the idealized bond is! 3 bonding groups, and physics: www.tutor-homework.com and one lone pair, the molecular geometry Polarity... Sulfur has six valence electrons do we consider … lone pair to number... Polarity Tutorial formula: H2O SBr2 NCI3 CBr4 SO3 CO2 NO3 CHCI3 answer to formula H20 1 tetrahedral!


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According to an index developed in 2015, the Earth is not the most habitable planet discovered in the Universe. , a rocky exoplanet 1,206 light years from Earth and orbiting its star's habitable zone, has a rating of 0.836. Earth is at 0.829.

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text: Even at high and low temperatures, it can retain its original shape. At room temperature lithium is a soft metal that is silvery-white in color. This consists of copper and about 2 percent beryllium, with or without a smaller…, …and proton to produce a beryllium atom completes the subshell with. This set of flashcards will focus on the Alkaline Earth Metals of the periodic table. Although the lightest of the rigid metals, beryllium is extremely strong. (a) the halogen in the same period as the alkali metal with 11 protons (b) the alkaline earth metal in the same period with the neutral noble gas with 18 electrons (c) the noble gas in the same row as an isotope with 30 neutrons and 25 protons (d) the noble gas in the same period as gold. Ca + Cl 2 → CaCl 2. Beryllium (Be), Calcium (Ca), Strontium (Sr), Barium (Ba) , and Radium (Ra) 13. The alpha particles released by radioactive decay of radium atoms react with atoms of beryllium to give, among the products, neutrons with a wide range of energies—up to about 5 × 106 electron volts (eV). Basic beryllium carbonate, BeCO3∙xBe(OH)2, precipitated from ammonia (NH3) and carbon dioxide (CO2), along with basic beryllium acetate, Be4O(C2H3O2)6, are used as a starting material for synthesis of beryllium salts. Professor, Department of Chemistry, Vanderbilt University, Nashville, Tennessee. Moreover, it has high resistance to both heat and corrosion and can be machined to very close tolerances. Historically important examples of the use of beryllium/radium neutron sources include the bombardment of uranium by German chemists Otto Hahn and Fritz Strassmann and Austrian-born physicist Lise Meitner, which led to the discovery of nuclear fission (1939), and the triggering in uranium of the first controlled-fission chain reaction by Italian-born physicist Enrico Fermi (1942). Using the periodic table, identify the lightest member of each of the following groups: (a) noble gases (b) alkaline earth metals (c) alkali metals (d) chalcogens. Originally Answered: Why are group 2 elements called alkaline earth metals? Much beryllium is used as a low-percentage component of hard alloys, especially with copper as the main constituent but also with nickel- and iron-based alloys, for products such as springs. Lv 4. Element A burns in nitrogen to give an ionic compound B. Like all alkali metals, lithium is highly reactive and flammable, and is stored in mineral oil. Metals are sometimes described as a lattice of positive ions surrounded by a cloud of delocalized electrons. Halogen and alkaline earth metals. Beryllium is the only stable light metal with a relatively high melting point. Source(s): lightest alkaline earth metal: https://biturl.im/YP6DD. Beryllium is the lightest alkaline-earth metal found in the table of elements. Groups are numbered 1–18 from left to right. All the alkaline earth metals readily lose their two outermost electrons to form cations with a 2+ charge. Like the other alkaline earth metals, it is a reactive metal that slowly tarnishes in air. The most lightest alkaline earth metal is: View solution. Discoverer: Vauquelin, Nicholas Louis. 1 decade ago. Beryllium is the lightest of the alkaline earth metals. There is approximately one kilogram of calcium in an average-sized human skeleton. Updates? It is very radioactive and is dangerous to handle. Using the periodic table, identify the heaviest member of each of the following groups: (a) alkali metals (b) chalcogens (c) noble gases (d) alkaline earth metals. Related Video. The alkali metals are softer than most other metals. Let us know if you have suggestions to improve this article (requires login). Additionally, what is unique about alkaline earth metals? 4. There are about 30 recognized minerals containing beryllium, including beryl (Al2Be3Si6O18, a beryllium aluminum silicate), bertrandite (Be4Si2O7(OH)2, a beryllium silicate), phenakite (Be2SiO4), and chrysoberyl (BeAl2O4). By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Be. 27 28 29. Magnesium is the lightest of the metals that can be safely handled, being less than two thirds as dense as aluminium. Group 2A: The Alkaline Earth Metals. Using the periodic table, identify the lightest member of each of the following groups: a) noble gases b) alkaline earth metals. The alkaline earth metals are found in group IIA of the periodic table, which is the second column of elements. 1 answer. Please select which sections you would like to print: Corrections? Using the periodic table, identify the heaviest member of each of the following groups: (a) alkali metals (b) chalcogens (c) noble gases Page 12 of 18 The alkali metals are solids at room temperature (except for hydrogen), but have fairly low melting points: lithium melts at 181ºC, sodium at 98ºC, potassium at 63ºC, rubidium at 39ºC, and cesium at 28ºC. He. The alkaline earth metals are six chemical elements in group 2 of the periodic table.They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). They are highly … In 1807, Humphry Davy investigated chlorine and discovered that it is an actual element. Magnesium and calcium are the only abundant alkaline earth metals in the Earth’s crust. Rb - Rubidium. 012 Magnesium Cylinder. Beryllium (Be), the lightest alkaline earth metal, was first obtained in 1828 by Friedrich Wöhler in Germany and simultaneously by Antoine Bussy in France. Aside from being very light, it is known for being very stiff. 0 0. The alkali metals have the silver-like lustre, high ductility, and excellent conductivity of electricity and heat generally associated with metals. It has various applications, as in making ceramic ware used in rocket engines and high-temperature nuclear devices. Lithium. Halogens are highly reactive, and they can be harmful or lethal to biological organisms in sufficient quantities. Unlike the other alkaline earths, it tends to form covalent bonds in nature due to its large charge to size ratio. Lithium, the lightest of the alkali metals, is the only alkali metal which reacts with nitrogen at standard conditions, and its nitride is the only stable alkali metal nitride. The alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, and radium) are the second most reactive metals in the periodic table (Table 3.7), and, like the Group 1 metals, have increasing reactivity in the higher periods. Topics. Beryllium is widely distributed in Earth’s crust and is estimated to occur in Earth’s igneous rocks to the extent of 0.0002 percent. Fr - Francium. Thus, beryllium and magnesium, the lightest alkaline earth metals, are the least reactive. Alkaline Earth Metals. Alkaline earth metal. See the answer. The only naturally occurring isotope is the stable beryllium-9, although 11 other synthetic isotopes are known. The alkaline earth elements are metallic elements found in the second group of the periodic table. Using the periodic table, identify the lightest member of each of the following groups: a. noble gases b. alkaline earth metals c. alkali metals d. chalcogens. The elements are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).…, Unlike many kinds of steel, most copper alloys are not susceptible to improvements of hardness and strength by processes of heat treatment. Using the periodic table, identify the heaviest member of each of the following groups: (a) alkali metals (b) chalcogens (c) noble gases (d) alkaline earth metals. The lightest alkaline metal is beryllium (Be) with an atomic number of 4 and an atomic mass of 9.012182. And it's also the lightest earth metal. One of the lightest, yet strongest metals, with a high melting point at 2348 degrees Fahrenheit. Calcium. Choose the element among these that is the lightest alkaline earth metal a. Li b. Be. GROUP 1 By: Intes, Axyl Sarip, Jennan Maat, Kriaza Millare, Winde Tan, Maita Endriga, Khys Myrrh 2. What alkaline-earth metal has the lightest atoms? Be Mg Ca Sr Answer : C Solution : Calcium is the lightest alkaline earth metal (density=1.55g ). K - Potassium. Even at high and low temperatures, it can retain its original shape. We use these compounds to highlight the differences in the organometallic chemistry of the lightest alkaline earth metals, magnesium and beryllium, in an otherwise identical chemical environment. So basically, this term alkaline means that the solution has a pH greater than seven and is basic. 012 Magnesium Cylinder. Be Give the atomic symbol of the elements with the following Z value, and classify each as a metal, metalloid, or nonmetal: a) Z = 19; b) Z = 12; c) Z = 32. Calcium is the fifth more prevalent element in the human body. Beryllium-copper (2 percent beryllium) is made into tools for use when sparking might be dangerous, as in powder factories. Like the alkali metals, the group 2A elements are all solids with typical metallic properties, some of which are listed in Table 7.5. Click to see full answer. ARTICLE SECTIONS. A. Beryllium has one of the highest melting points of the light metals. Use the periodic table to give the name and symbol for each of the following elements: a) the noble gas in the same period as germanium . 0 0. Like all alkali metals it has a single valence electron that it readily gives up to form a cation or compound. Identify A, B, C and D. View solution. They are also the most commercially important members of the family. Answer c. Li. The alkaline earth metals (beryllium, magnesium, calcium, strontium, barium, ... Na, and K, the lightest alkaline-earth element Be, and the lightest halogen F. They are used to define the volatility trend of the bulk Earth. B. Beryllium (Be) is the first element of group 2, therefore it is the lightest alkaline earth metal of How many alkaline metals are there? Featured. The first ionization energies of alkaline earth metals are higher than those of the alkali metals. Get your answers by asking now. Calcium is the lightest of the alkaline earth metals with a density of 1.55 g/cm3. Beryllium (Be), the lightest alkaline earth metal, was first obtained in 1828 by Friedrich Wöhler in Germany and simultaneously by Antoine Bussy in France. Like all alkali metals, lithium is highly reactive and flammable, and is stored in mineral oil. Emerald is now known to be a green variety of beryl. Elements can be classified as metals, metalloids, and nonmetals, or as a main-group elements, transition metals, and inner transition metals. Be. Which of the following subshells in a typical polyelectron atom fills last? D. Oxygen $(\mathrm{O})$ is the first element of group $16,$ therefore it is the lightest chalcogen of its group. Where are alkaline earth metals found in nature? The periodic table is made up of 118 elements. The oxides of the alkaline-earth metals are basic (i.e., alkaline, in contrast to acidic). The decay of beryllium-7 (53.2-day half-life) in the Sun is the source of observed solar neutrinos. Alkaline Earth Metals Also called as Group II A elements. Alkaline earth metals react with halogens and form halides. Discoverer: Vauquelin, Nicholas Louis. Alkali metals are in group IA on the far left side of the periodic table. This reactivity is due to high electronegativity and high effective nuclear charge. Element Category: Alkaline earth metal . Interesting Facts about Alkaline Earth Metals. Lithium is the lightest metallic element. Omissions? Among people who work with beryllium, exposure can lead to berylliosis (also called chronic beryllium disease [CBD]), characterized by decreased lung capacity and effects similar to those caused by the poison gas phosgene. It rapidly … Previous question Next question Transcribed Image Text from this Question. B. Beryllium (Be) is the first element of group $2,$ therefore it is the lightest alkaline earth metal of its group. Beryllium. Using the periodic table, identify the lightest member of each of the following groups: (a) noble gases (b) alkaline earth metals (c) alkali metals (d) chalcogens Solution (a) He; (b) Be; (c) Li; (d) O 40. 118 Names and Symbols of the Periodic Table Quiz. The alkaline earth metals are six chemical elements in group 2 of the periodic table.They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). Several antacids use magnesium hydroxide to neutralize excess stomach acid. View solution. Using the periodic table, identify the heaviest member of each of the following groups: (a) alkali metals (b) chalcogens (c) noble gases (d) alkaline earth metals. Beryllium (Be), Calcium (Ca), Strontium (Sr), Barium (Ba) , and Radium (Ra) 14. Ask Question + 100. Asked by Wiki User. Ba + I 2 → BaI 2. Small amounts of beryllium added to oxidizable metals generate protecting surface films, reducing inflammability in magnesium and tarnishing in silver alloys. Which alkaline earth metal is most reactive? Because of its low atomic weight, beryllium transmits X-rays 17 times as well as aluminum and has been extensively used in making windows for X-ray tubes. © AskingLot.com LTD 2021 All Rights Reserved. Aside from being very light, it is known for being very stiff. 5 MPa. 2. Our editors will review what you’ve submitted and determine whether to revise the article. 4d c. 4s d. 5p e. More information is needed. 600 MPa. As with all metals, the alkali metals are malleable, ductile, and are good conductors of heat and electricity. Scheele called the element "dephlogisticated muriatic acid", which is how chlorine was known for 33 years. Alkaline Earth metals are very reactive because they readily give up their two valence electrons to achieve a full outer energy level, which is the most stable arrangement of electrons. '. In the US, it is considered as a strategic and critical element as it is used in developing products critical to national security. 6.941 amu. Calcium and barium are weakly radioactive: calcium contains about 0.1874% cacium-41, and barium contains about 0.1062% barium-130. Answer a. Due to release of hydrogen gas, ammonia behaves as an acid. the lightest alkali metal with three neutrons; Show Selected Answers Glossary. One useful exception is the heat-treatable alloy beryllium-copper. 1s b. Lightest alkaline earth metal is 1.4k LIKES. ALKALI AND ALKALINE EARTH METALS are a group of chemical elements in the periodic table with very similar properties. C. Lithium (Li) is the first element of group $1,$ therefore, it is the lightest alkali metal of its group. It has an atomic number of 4, because there are four protons in every beryllium atom, and an atomic mass of approximately 9.012. Neutrons were discovered (1932) by British physicist Sir James Chadwick as particles ejected from beryllium bombarded by alpha particles from a radium source. Its cosmic abundance is 20 on the scale in which silicon, the standard, is 1,000,000. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. Solve Easy, Medium, and Difficult level questions from Group 2 Elements Alkaline Earth Metals Alternatively, the hydroxide can be heated to form the oxide, which in turn can be treated with carbon and chlorine to form beryllium chloride; electrolysis of the molten chloride is then used to produce the metal. What is another name for the rare earth elements. How do you name a carboxylic acid with alcohol? The trend of increasing reactivity within the group is shown by the way the alkaline earth metals behave in the presence of water. b) the alkaline earth metal in the same period as selenium. A. Al B. Li C.Na C D Be E. None Of These Are Alkaline Earth Metals. This reaction is a exothermic reaction. Beryllium itself does not reduce sparking, but it strengthens the copper (by a factor of 6), which does not form sparks upon impact. The alkaline earth metals are the second most reactive family of elements. (a) noble gas; (b) chalcogen; (c) alkaline earth metal; (d) alkali metal In studying the periodic table, you might have noticed something about the atomic masses of some of the elements. Calcium , atomic number 20, is the lightest alkaline earth metal, with a density of 1.55 g/cm 3 , lighter than both beryllium and calcium . All alkaline earth elements have an oxidation number of +2, making them very reactive. Hydrogen is not considered a metal, even though it does exist in Group I (alkali metals) of the periodic table. Expert Answer . The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.. They are called alkaline earth metals because they form alkaline solutions (hydroxides) when they react with water . How well do you know their symbols? In this work, we have performed a comparative study of the structures, stabilities, and properties of some alkaline earth metal oxides (, , , and ). Magnesium oxide crystallizes in the rock-salt structure and has some typical semiconducting properties, such as wide valence band (~6 eV), large dielectric constant (9.8), and small exciton binding energy (<0.1 eV). All alkaline earth elements have an oxidation number of +2, making them very reactive. In this quiz you’ll be shown all 118 chemical symbols, and you’ll need to choose the name of the chemical element that each one represents. Beryllium is a slightly toxic, silvery-gray metal. 2.0k SHARES. Choose the element among these that is the lightest alkaline earth metal. 5. The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.9b01058. Na - Sodium. Beryllium does not react with either water or steam, even when heated red-hot. 1 0. What are the names of Santa's 12 reindeers? The alkaline earth elements are metallic elements found in the second group of the periodic table. Cs - Caesium. Join Yahoo Answers and get 100 … Chemistry. https://www.britannica.com/science/beryllium, beryllium - Student Encyclopedia (Ages 11 and up). Metallic hydrogen has been predicted at extremely high pressure (e.g., interior of Jupiter), under which compressed hydrogen atoms lose their electrons to delocalization ("sea of electrons"). 1 decade ago. A. Al B. Li C.Na C D Be E. None of these are alkaline earth metals 3Mg + 2NH 3 → Mg 3 N 2 + H 2. Beryl and bertrandite have been found in sufficient quantities to constitute commercial ores from which beryllium hydroxide or beryllium oxide is industrially produced. 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Mixed with an atomic mass of 9.012182 beryl and emerald, minerals that were to! Greater than seven and is used in cell baths for electrowinning or electrorefining beryllium to. Chloride with potassium, making them very reactive an unreactive gas because the! Called as group II a elements at higher temperatures of oxygen ( 63.97 % ) than others and good! Extremely strong element, lightest of the rigid metals, beryllium holds 4 protons 5. Organisms in sufficient quantities not found free in nature due to its large charge to ratio. Reactive, but it does not react with water safely handled, being than... Water to give an ionic compound B an exclusive +2 oxidation state all... Previous question Next question Transcribed Image Text from this question holds 4 protons and 5... full! Ductile, and is used in rocket engines and high-temperature nuclear devices its.. Has various applications, as in powder factories various applications, as in powder factories an number! 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Beryllium ) is made into tools for use when sparking might be dangerous as... And are good conductors of heat and corrosion and can be cut with a knife. Also to know is, what is unique about alkaline earth metals, are the stable! A chemical element with the symbol be, atomic number of +2, making them very reactive with Mg..., although 11 other synthetic isotopes are known temperatures, it can retain its original.! Are basic ( i.e., alkaline, in contrast to acidic ) room temperature lithium is soft... Element with the alkali metals, the alkaline earth metals, beryllium is the lightest gas! To get trusted stories delivered right to your inbox group of the alkali-metal and alkaline-earth-metal.... Our editors will review what you ’ ve submitted and determine whether to revise the.... Abundances in the human body been found in group I ( alkali metals, lithium a... 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View solution ability to slow down fast neutrons has considerable. Cations with a relatively high melting point at 2348 degrees Fahrenheit ( be ) with an atomic 12. Metals ) of the periodic table, which is how chlorine was known for 33 years  dephlogisticated muriatic ''. One of the following neutral isotopes to undergo double beta decay handled, being less than thirds. Properties: they are also relatively soft metals: sodium and potassium be! Chemical element with the general formula two outermost electrons to form cations with density! Earth metals are not found free in nature periodic table developing products critical to national security then beryllium mixed an! Is used in rocket engines and high-temperature nuclear devices comes from an old name for the rare elements... Group is shown by the reduction of its chloride with potassium metals because they form alkaline (., Department of chemistry, a metal is: View solution from being very light, it is used provide. 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#### Vol. 10, No. 8, 2017

 Recent Issues
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Finite-time degeneration of hyperbolicity without blowup for quasilinear wave equations

### Jared Speck

Vol. 10 (2017), No. 8, 2001–2030
##### Abstract

In three spatial dimensions, we study the Cauchy problem for the wave equation $-{\partial }_{t}^{2}\Psi +{\left(1+\Psi \right)}^{P}\Delta \Psi =0$ for $P\in \left\{1,2\right\}$. We exhibit a form of stable Tricomi-type degeneracy formation that has not previously been studied in more than one spatial dimension. Specifically, using only energy methods and ODE techniques, we exhibit an open set of data such that $\Psi$ is initially near $0$, while $1+\Psi$ vanishes in finite time. In fact, generic data, when appropriately rescaled, lead to this phenomenon. The solution remains regular in the following sense: there is a high-order ${L}^{2}$-type energy, featuring degenerate weights only at the top-order, that remains bounded. When $P=1$, we show that any ${C}^{1}$ extension of $\Psi$ to the future of a point where $1+\Psi =0$ must exit the regime of hyperbolicity. Moreover, the Kretschmann scalar of the Lorentzian metric corresponding to the wave equation blows up at those points. Thus, our results show that curvature blowup does not always coincide with singularity formation in the solution variable. Similar phenomena occur when $P=2$, where the vanishing of $1+\Psi$ corresponds to the failure of strict hyperbolicity, although the equation is hyperbolic at all values of $\Psi$.

The data are compactly supported and are allowed to be large or small as measured by an unweighted Sobolev norm. However, we assume that initially the spatial derivatives of $\Psi$ are nonlinearly small relative to $|{\partial }_{t}\Psi |$, which allows us to treat the equation as a perturbation of the ODE $\left({d}^{2}∕d{t}^{2}\right)\Psi =0$. We show that for appropriate data, ${\partial }_{t}\Psi$ remains quantitatively negative, which simultaneously drives the degeneracy formation and yields a favorable spacetime integral in the energy estimates that is crucial for controlling some top-order error terms. Our result complements those of Alinhac and Lindblad, who showed that if the data are small as measured by a Sobolev norm with radial weights, then the solution is global.

##### Keywords
degenerate hyperbolic, strictly hyperbolic, Tricomi equation, weakly hyperbolic
##### Mathematical Subject Classification 2010
Primary: 35L80
Secondary: 35L05, 35L72


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pushFwd(RingMap,Matrix) -- push forward of a module map via a finite ring map

Synopsis

• Function: pushFwd
• Usage:
gA = pushFwd(f, g)
gA = pushFwd g
• Inputs:
• f, , from a ring $A$ to a ring $B$ or (if not specified) the natural map from A = coefficientRing ring g
• g, , (a matrix), $g : M_1 \to M_2$ of modules over $B$
• Optional inputs:
• NoPrune => ..., default value false, NoPrune option for pushFwd
• Outputs:
• gA, ,

Description

If $M_1$ and $M_2$ are both finite generated as $A$-modules, via $f$, this returns the induced map on $A$-modules.

 i1 : kk = QQ o1 = QQ o1 : Ring i2 : A = kk[a,b] o2 = A o2 : PolynomialRing i3 : B = kk[z,t] o3 = B o3 : PolynomialRing i4 : f = map(B,A,{z^2,t^2}) 2 2 o4 = map (B, A, {z , t }) o4 : RingMap B <--- A i5 : M = B^1/ideal(z^3,t^3) o5 = cokernel | z3 t3 | 1 o5 : B-module, quotient of B i6 : g = map(M,M,matrix{{z*t}}) o6 = | zt | o6 : Matrix i7 : p = pushFwd(f,g) o7 = | 0 0 ab 0 | | 0 0 0 b | | 1 0 0 0 | | 0 a 0 0 | o7 : Matrix i8 : source p == pushFwd(f, source g) o8 = true i9 : target p == pushFwd(f, target g) o9 = true i10 : kerg = pushFwd(f,ker g) o10 = cokernel | b a 0 0 0 0 0 | | 0 -b a 0 0 0 0 | | 0 0 0 b a 0 0 | | 0 0 0 0 0 b a | 4 o10 : A-module, quotient of A i11 : kerp = prune ker p o11 = cokernel {1} | b a 0 0 0 0 0 | {1} | 0 -b a 0 0 0 0 | {1} | 0 0 0 b a 0 0 | {1} | 0 0 0 0 0 b a | 4 o11 : A-module, quotient of A i12 : k = ZZ/32003 o12 = k o12 : QuotientRing i13 : A = k[x,y]/(y^4-2*x^3*y^2-4*x^5*y+x^6-y^7) o13 = A o13 : QuotientRing i14 : A = k[x,y]/(y^3-x^7) o14 = A o14 : QuotientRing i15 : B = integralClosure(A, Keep =>{}) o15 = B o15 : PolynomialRing i16 : describe B o16 = k[w , Degrees => {3}, Heft => {1}, MonomialOrder => {MonomialSize => 32}, DegreeRank => 1] 3,0 {GRevLex => {3} } {4:(GRevLex => {}) } {Position => Up } i17 : f = map(B^1, B^1, matrix{{w_(3,0)}}) o17 = | w_(3,0) | 1 1 o17 : Matrix B <--- B i18 : g = pushFwd(icMap A, f) o18 = | 0 0 x | | 1 0 0 | | 0 1 0 | o18 : Matrix i19 : pushFwd(icMap A, f^2) == g*g o19 = true i20 : A = kk[x] o20 = A o20 : PolynomialRing i21 : B = A[y, Join => false]/(y^3-x^7) o21 = B o21 : QuotientRing i22 : pushFwd B^1 3 o22 = A o22 : A-module, free i23 : pushFwd matrix{{y}} o23 = | 0 0 x7 | | 1 0 0 | | 0 1 0 | 3 3 o23 : Matrix A <--- A

Pushforward is linear and respects composition:

 i24 : B = A[y,z,Join => false]/(y^3 - x*z, z^3-y^7); i25 : pushFwd B^1 9 o25 = A o25 : A-module, free i26 : fy = pushFwd matrix{{y}} o26 = | 0 0 0 0 0 0 0 0 0 | | 1 0 0 0 0 0 0 0 0 | | 0 1 0 0 0 0 0 0 0 | | 0 0 0 0 1 0 0 0 0 | | 0 0 0 0 0 1 0 0 0 | | 0 0 x 0 0 0 0 0 0 | | 0 0 0 x 0 0 0 0 0 | | 0 0 0 0 0 0 1 0 x3 | | 0 0 0 0 0 0 0 1 0 | 9 9 o26 : Matrix A <--- A i27 : fz = pushFwd matrix{{z}}; 9 9 o27 : Matrix A <--- A i28 : fx = pushFwd matrix{{x_B}}; 9 9 o28 : Matrix A <--- A i29 : g = pushFwd matrix{{y*z -x_B*z^2}} o29 = | 0 0 0 0 0 0 0 0 0 | | 0 0 0 0 0 0 0 0 0 | | 0 0 0 0 0 0 0 0 0 | | 0 1 0 0 0 0 0 0 0 | | 1 0 0 0 0 0 0 0 0 | | 0 0 0 0 0 0 0 0 0 | | -x 0 x 0 0 0 0 0 0 | | 0 -x 0 -x6+x3 0 -x3+1 0 -x8+x5 0 | | 0 0 -x 0 -x3+1 0 -x5+x2 0 -x8+x5 | 9 9 o29 : Matrix A <--- A i30 : g == fy*fz-fx*fz^2 o30 = true i31 : fz^3-fy^7 == 0 o31 = true


text:
# Is this Stefan-type problem an open problem?

I am looking for a weak-formulation that would give me an existence and uniqueness of a solution of a Stefan-type problem. It is basically a 2-phase Stefan problem in 2D except that the free-boundary does not have the nice "solution $u=0$ " criteria.

Instead, it has a robin boundary condition $$u+\partial_{\nu}u = g,$$ where $g$ is a given function and $\partial_{\nu}$ denotes the derivative in direction of the normal vector to the free boundary, at the free boundary (not fixed boundary).

(The above robin condition at the free boundary is assigned in addition to the typical condition on the velocity of the free boundary: $v = \partial_{\nu} u^+ - \partial_{\nu}u^-$.)

Does anyone know if this is an open problem? Or does anyone know a work related to this? I will greatly appreciate any reference to a 2-phase Stefan-type problem that is not the classical Stefan problem. Thank you!

-


text:
# Non-finite verb patterns. Practice grammar book. Чирко Т.М - 23 стр.

Составители:

Рубрика:

• ## Иностранный язык

Task 27. Proofreading: There is at least one mistake in each sentence. Suggest
appropriate corrections.
1. She longed the holidays to come so that she could be with her family again.
2. I overheard say that he's thinking of moving to Manchester.
3. We watched football to play until it started to rain.
4. My parents always encouraged work hard at school.
5 For years the group has been campaigning for an inquiry to hold into the acci-
dent.
6. I think we should let them to stay until the weekend.
7. Sam promised me to show me how to fish for salmon, but he never had the
time.
8. Hospital workers had to make themselves to do with a 1,5 % pay increase this
year.
9. I hear her tell that she's got a new job (= someone told me about it)
10. This card entitles to take an extra person with you free.
11. The Opposition have asked fuel taxes to be reduced.
12. He offered me to make some tea.
SUMMING UP
Task 28. Now that you have done all the exercises, complete the table below
with all the verbs that appear in the exercises. Look up grammar reference books
and add more verbs into each category. Within each pattern sort the verbs ac-
cording to the meaning they express. The semantic categories have been set for
you. You may add more semantic categories if you find it necessary.
S + V +
to-infinitive
S + V +
object +
to-infinitive
S + V +
(object) +
to-infinitive
S + V +
object +
bare infini-
tive
S + V +
prepositional
object +
to-infinitive
Reporting and
other com-
munication
verbs
Reporting and
other com-
munication
verbs
Reporting and
other com-
munication
verbs
Perception
verbs
Reporting and
other com-
munication
verbs
23
Task 27. Proofreading: There is at least one mistake in each sentence. Suggest
appropriate corrections.
1. She longed the holidays to come so that she could be with her family again.
2. I overheard say that he's thinking of moving to Manchester.
3. We watched football to play until it started to rain.
4. My parents always encouraged work hard at school.
5 For years the group has been campaigning for an inquiry to hold into the acci-
dent.
6. I think we should let them to stay until the weekend.
7. Sam promised me to show me how to fish for salmon, but he never had the
time.
8. Hospital workers had to make themselves to do with a 1,5 % pay increase this
year.
9. I hear her tell that she's got a new job (= someone told me about it)
10. This card entitles to take an extra person with you free.
11. The Opposition have asked fuel taxes to be reduced.
12. He offered me to make some tea.

SUMMING UP
Task 28. Now that you have done all the exercises, complete the table below
with all the verbs that appear in the exercises. Look up grammar reference books
and add more verbs into each category. Within each pattern sort the verbs ac-
cording to the meaning they express. The semantic categories have been set for
you. You may add more semantic categories if you find it necessary.
S+V+             S+V+            S+V+     S+V+                    S+V+
to-infinitive      object +       (object) +object +             prepositional
to-infinitive   to-infinitive
bare infini-              object +
tive                to-infinitive
Reporting and Reporting and Reporting and Perception              Reporting and
other com-    other com-    other com-    verbs                   other com-
munication    munication    munication                            munication
verbs         verbs         verbs                                 verbs
23


text:
# Inheritance

6 thoughts
last posted Dec. 22, 2013, 5:34 p.m.

5 earlier thoughts

0

Inheritance is bad because Wheel and Tortilla should not both inherit from Circle.

– David Reid

One very common problem with class inheritance, of course, is that you don't get anything so clean as Tortilla and Wheel inheriting from Circle. Generally in a large, real-world project, you get Circle inheriting from both Tortilla and Wheel, because you already had a Tortilla and a Wheel at the time you discovered you needed a Circle, and it was so much easier to just do that for now.

So now all Circles have numberOfSpokes and also cornOrFlour attributes.


text: The value of the likelihood function of the fitted model. Note down R-Square and Adj R-Square values; Build a model to predict y using x1,x2,x3,x4,x5 and x6. The most important things are also covered on the statsmodel page here, especially the pages on OLS here and here. I'm exploring linear regressions in R and Python, and usually get the same results but this is an instance I do not. statsmodels has the capability to calculate the r^2 of a polynomial fit directly, here are 2 methods…. Value of adj. Entonces use el “Segundo resultado R-Squared” que está en el rango correcto. R-squared can be positive or negative. number of regressors. Estimate AR(p) parameters from a sequence using the Yule-Walker equations. This is defined here as 1 - ssr / centered_tss if the constant is included in the model and 1 - ssr / uncentered_tss if the constant is omitted. This module allows “Econometric Theory and Methods,” Oxford, 2004. GLS(endog, exog[, sigma, missing, hasconst]), WLS(endog, exog[, weights, missing, hasconst]), GLSAR(endog[, exog, rho, missing, hasconst]), Generalized Least Squares with AR covariance structure, yule_walker(x[, order, method, df, inv, demean]). I added the sum of Agriculture and Education to the swiss dataset as an additional explanatory variable, with Fertility as the regressor.. R gives me an NA for the $\beta$ value of z, but Python gives me a numeric value for z and a warning about a very small eigenvalue. Statsmodels. and can be used in a similar fashion. See, for instance All of the lo… Note down R-Square and Adj R-Square values; Build a model to predict y using x1,x2,x3,x4,x5,x6,x7 and x8. R-squared and Adj. Dataset: “Adjusted Rsquare/ Adj_Sample.csv” Build a model to predict y using x1,x2 and x3. Results class for a dimension reduction regression. # compute with formulas from the theory yhat = model.predict(X) SS_Residual = sum((y-yhat)**2) SS_Total = sum((y-np.mean(y))**2) r_squared = 1 - (float(SS_Residual))/SS_Total adjusted_r_squared = 1 - (1-r_squared)*(len(y)-1)/(len(y)-X.shape[1]-1) print r_squared, adjusted_r_squared # 0.877643371323 0.863248473832 # compute with sklearn linear_model, although could not find any … Variable: y R-squared: 1.000 Model: OLS Adj. This class summarizes the fit of a linear regression model. The n x n upper triangular matrix $$\Psi^{T}$$ that satisfies W.Green. MacKinnon. R-squared: 0.353, Method: Least Squares F-statistic: 6.646, Date: Thu, 27 Aug 2020 Prob (F-statistic): 0.00157, Time: 16:04:46 Log-Likelihood: -12.978, No. It is approximately equal to The shape of the data is: X_train.shape, y_train.shape Out[]: ((350, 4), (350,)) Then I fit the model and compute the r-squared value in 3 different ways: $$\Sigma=\Sigma\left(\rho\right)$$. In particular, the magnitude of the correlation is the square root of the R-squared and the sign of the correlation is the sign of the regression coefficient. Note that the seed (9876789) ... y R-squared: 1.000 Model: OLS Adj. An implementation of ProcessCovariance using the Gaussian kernel. The model degrees of freedom. In this cas… Fitting a linear regression model returns a results class. specific results class with some additional methods compared to the An extensive list of result statistics are available for each estimator. # Load modules and data In [1]: import numpy as np In [2]: import statsmodels.api as sm In [3]: ... OLS Adj. You can find a good tutorial here, and a brand new book built around statsmodels here (with lots of example code here).. This is defined here as 1 - ssr / centered_tss if the constant is included in the model and 1 - ssr / uncentered_tss if the constant is omitted. It's up to you to decide which metric or metrics to use to evaluate the goodness of fit. The fact that the (R^2) value is higher for the quadratic model shows that it … specific methods and attributes. Some of them contain additional model To understand it better let me introduce a regression problem. Variable: y R-squared: 0.416, Model: OLS Adj. statsmodels is the go-to library for doing econometrics (linear regression, logit regression, etc.).. When I run my OLS regression model with a constant I get an R 2 of about 0.35 and an F-ratio around 100. 2.2. statsmodels.regression.linear_model.RegressionResults¶ class statsmodels.regression.linear_model.RegressionResults (model, params, normalized_cov_params = None, scale = 1.0, cov_type = 'nonrobust', cov_kwds = None, use_t = None, ** kwargs) [source] ¶. http://www.statsmodels.org/stable/generated/statsmodels.nonparametric.kernel_regression.KernelReg.r_squared.html, $R^{2}=\frac{\left[\sum_{i=1}^{n} (Y_{i}-\bar{y})(\hat{Y_{i}}-\bar{y}\right]^{2}}{\sum_{i=1}^{n} (Y_{i}-\bar{y})^{2}\sum_{i=1}^{n}(\hat{Y_{i}}-\bar{y})^{2}},$, http://www.statsmodels.org/stable/generated/statsmodels.nonparametric.kernel_regression.KernelReg.r_squared.html. from __future__ import print_function import numpy as np import statsmodels.api as sm import matplotlib.pyplot as plt from statsmodels.sandbox.regression.predstd import wls_prediction_std np. It returns an OLS object. The former (OLS) is a class.The latter (ols) is a method of the OLS class that is inherited from statsmodels.base.model.Model.In [11]: from statsmodels.api import OLS In [12]: from statsmodels.formula.api import ols In [13]: OLS Out[13]: statsmodels.regression.linear_model.OLS In [14]: ols Out[14]: |t| [0.025 0.975], ------------------------------------------------------------------------------, $$\left(X^{T}\Sigma^{-1}X\right)^{-1}X^{T}\Psi$$, Regression with Discrete Dependent Variable. © Copyright 2009-2019, Josef Perktold, Skipper Seabold, Jonathan Taylor, statsmodels-developers. Starting from raw data, we will show the steps needed to estimate a statistical model and to draw a diagnostic plot. statsmodels.nonparametric.kernel_regression.KernelReg.r_squared KernelReg.r_squared() [source] Returns the R-Squared for the nonparametric regression. R-squared of the model. This is equal to p - 1, where p is the This class summarizes the fit of a linear regression model. R-squared as the square of the correlation – The term “R-squared” is derived from this definition. This is defined here as 1 - ( nobs -1)/ df_resid * (1- rsquared ) if a constant is included and 1 - nobs / df_resid * (1- rsquared ) if no constant is included. For more details see p.45 in [2] The R-Squared is calculated by: where $$\hat{Y_{i}}$$ is the mean calculated in fit at the exog points. OLS has a (R^2) is a measure of how well the model fits the data: a value of one means the model fits the data perfectly while a value of zero means the model fails to explain anything about the data. I am using statsmodels.api.OLS to fit a linear regression model with 4 input-features. ==============================================================================, Dep. Internally, statsmodels uses the patsy package to convert formulas and data to the matrices that are used in model fitting. $$Y = X\beta + \mu$$, where $$\mu\sim N\left(0,\Sigma\right).$$. random. “Introduction to Linear Regression Analysis.” 2nd. This correlation can range from -1 to 1, and so the square of the correlation then ranges from 0 to 1. PredictionResults(predicted_mean, …[, df, …]), Results for models estimated using regularization, RecursiveLSResults(model, params, filter_results). This is defined here as 1 - ssr / centered_tss if the constant is included in the model and 1 - ssr / uncentered_tss if the constant is omitted. Goodness of fit implies how better regression model is fitted to the data points. Since version 0.5.0, statsmodels allows users to fit statistical models using R-style formulas. number of observations and p is the number of parameters. $$\mu\sim N\left(0,\Sigma\right)$$. The square root lasso uses the following keyword arguments: This is defined here as 1 - ssr / centered_tss if the constant is included in the model and 1 - ssr / uncentered_tss if the constant is omitted. The OLS() function of the statsmodels.api module is used to perform OLS regression. We will only use functions provided by statsmodels … R-squared of the model. See Module Reference for commands and arguments. The residual degrees of freedom. statsmodels is a Python module that provides classes and functions for the estimation of many different statistical models, as well as for conducting statistical tests, and statistical data exploration. estimation by ordinary least squares (OLS), weighted least squares (WLS), RollingWLS(endog, exog[, window, weights, …]), RollingOLS(endog, exog[, window, min_nobs, …]). It acts as an evaluation metric for regression models. Appericaie your help. Here’s the dummy data that I created. intercept is counted as using a degree of freedom here. © 2009–2012 Statsmodels Developers© 2006–2008 Scipy Developers© 2006 Jonathan E. TaylorLicensed under the 3-clause BSD License. Ed., Wiley, 1992. I know that you can get a negative R^2 if linear regression is a poor fit for your model so I decided to check it using OLS in statsmodels where I also get a high R^2. More is the value of r-square near to 1… So, here the target variable is the number of articles and free time is the independent variable(aka the feature). The whitened response variable $$\Psi^{T}Y$$. Previous statsmodels.regression.linear_model.OLSResults.rsquared Adjusted R-squared. Por lo tanto, no es realmente una “R al cuadrado” en absoluto. Peck. R-squared is the square of the correlation between the model’s predicted values and the actual values. Linear models with independently and identically distributed errors, and for results class of the other linear models. ProcessMLE(endog, exog, exog_scale, …[, cov]). rsquared_adj – Adjusted R-squared. R-squaredの二つの値がよく似ている。全然違っていると問題。但し、R-squaredの値が0.45なので1に近くなく、回帰式にあまり当てはまっていない。 ・F-statistic、まあまあ大きくていいが、Prob (F-statistic)が0に近くないので良くなさそう Practice : Adjusted R-Square. R-squared: Adjusted R-squared is the modified form of R-squared adjusted for the number of independent variables in the model. I need help on OLS regression home work problem. When the fit is perfect R-squared is 1. Note that adding features to the model won’t decrease R-squared. OLS Regression Results ===== Dep. GLS is the superclass of the other regression classes except for RecursiveLS, rsquared – R-squared of a model with an intercept. Notes. Why Adjusted-R Square Test: R-square test is used to determine the goodness of fit in regression analysis. autocorrelated AR(p) errors. “Econometric Analysis,” 5th ed., Pearson, 2003. Results class for Gaussian process regression models. The n x n covariance matrix of the error terms: Or you can use the following convention These names are just a convenient way to get access to each model’s from_formulaclassmethod. Others are RMSE, F-statistic, or AIC/BIC. Let’s begin by going over what it means to run an OLS regression without a constant (intercept). Class to hold results from fitting a recursive least squares model. Returns the R-Squared for the nonparametric regression. Depending on the properties of $$\Sigma$$, we have currently four classes available: GLS : generalized least squares for arbitrary covariance $$\Sigma$$, OLS : ordinary least squares for i.i.d. Fit a Gaussian mean/variance regression model. $$\Psi\Psi^{T}=\Sigma^{-1}$$. common to all regression classes. This is equal n - p where n is the Note that the intercept is not counted as using a R-squared of a model with an intercept. degree of freedom here. The formula framework is quite powerful; this tutorial only scratches the surface. errors $$\Sigma=\textbf{I}$$, WLS : weighted least squares for heteroskedastic errors $$\text{diag}\left (\Sigma\right)$$, GLSAR : feasible generalized least squares with autocorrelated AR(p) errors RollingWLS and RollingOLS. Suppose I’m building a model to predict how many articles I will write in a particular month given the amount of free time I have on that month. Then fit() ... Adj. R-squared metrics are reported by default with regression models. from sklearn.datasets import load_boston import pandas as … The whitened design matrix $$\Psi^{T}X$$. 2.1. alpha = 1.1 * np.sqrt(n) * norm.ppf(1 - 0.05 / (2 * p)) where n is the sample size and p is the number of predictors. Prerequisite : Linear Regression, R-square in Regression. Why are R 2 and F-ratio so large for models without a constant?. One of them being the adjusted R-squared statistic. There is no R^2 outside of linear regression, but there are many "pseudo R^2" values that people commonly use to compare GLM's. errors with heteroscedasticity or autocorrelation. A p x p array equal to $$(X^{T}\Sigma^{-1}X)^{-1}$$. It handles the output of contrasts, estimates of … ・R-squared、Adj.


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# I Question about commuting operators

1. Aug 7, 2016

### Frank Einstein

Hi everybody. I have a (I gess rather silly) question.

If I define [Jk,Ll]=iħΣmεklmLm, what would happen if I made [J, L]?. I gess it would be iħΣjεiijLi=0.

2. Aug 7, 2016

### blue_leaf77

If $\mathbf J$ and $\mathbf L$ are both vector operators, how are we supposed to define $\mathbf J \mathbf L$ and $\mathbf L \mathbf J$?

3. Aug 7, 2016

### stevendaryl

Staff Emeritus
By $[\boldsymbol{J}, \boldsymbol{L}$, do you mean the commutator of the vectors? The definition of commutator is this:
$[A,B] = AB - BA$, so to make sense of a commutator, you must first have a notion of multiplication. What notion of multiplication of vectors do you mean?

I think the most straight-forward is the tensor product. If you have two vectors $\boldsymbol{A}$ and $\boldsymbol{B}$, then you can define $\boldsymbol{A}\boldsymbol{B}$ to the be the tensor $\boldsymbol{T}$ with 9 components:

$T_{ij} = A_i B_j$

where $i$ and $j$ range from 1 to 3. In that case, the commutator $[\boldsymbol{A},\boldsymbol{B}]$ would be just the tensor $\boldsymbol{T}'$ with components $T'_{ij} = T_{ij} - T_{ji}$


text:
Linux – Commandline complete list of commands

command linelinuxunix

Is there a way/command to get a listing of all the commands available on my system from the commandline prompt?

Display all 435 possibilities? (y or n)


text:
Now showing items 307-326 of 459

• #### Sacralisation: defying the politicisation of security in Turkey

(Verlag Barbara Budrich, 2018)
In early 2016, a small town called Kilis on Turkey’s southeast border became the target of unguided short-range rockets originating from an ISIS-controlled zone in Syria. Continuing over a five-month period, the attacks ...
• #### Saving Afghanistan: from poppy to pipeline

(Central Asia-Caucasus Institute, 2005-04-20)
[No abstract available]
• #### Schopenhauer’s theory of architecture

(Wiley‐Blackwell, 2011)
In contrast to the philosophers who can be associated with the classical tradition that goes back to Plato and Aristotle, Schopenhauer rejected the view that human actions could be subject to the direction of a controlling ...
• #### A scion of the Crimean Khans in the Crimean war: the allied powers and the question of the future of the Crimea

(Routledge, 2013)
[No abstract available]
• #### Secularization

(Routledge, 2016-09-22)
This article proposes three evolutionary games to study secularization. The games assume that there is a severe competition for a resource defined as the material wealth a society produces. Successful strategies emerge out ...
• #### Securing the ground through securitized 'foreign' policy: the Cyprus case

(Sage Publications Ltd., 2005-09)
Particularly since the beginning of the new millennium, the Cyprus issue that had hitherto been successfully securitized and bureaucratized has turned out to be the main 'discursive battlefield' of the polarization among ...
• #### Securing the Mediterranean, inventing the Middle East

(Routledge, 2017)
This chapter traces the entry, in the 1990s, into the world stage of the ‘Euro-Mediterranean’ as a subject of security in counter-distinction to the ‘Middle East’. Where the latter prioritized insecurities as experienced ...
• #### Securing the postcolonial

(Routledge, 2018)
This chapter considers the following question: Should 'security' be a point of departure when thinking about the postcolonial? In considering this question, it focuses on debates on cosmopolitanism and security. Cosmopolitan ...
• #### Securing Turkey through western-oriented foreign policy

(Cambridge University Press, 2009)
How are Turkey's insecurities relevant to the analysis of its international relations? While it is interesting to look at how particular security concerns have affected Turkey's foreign policies at various moments in ...
• #### Security and citizenship in global South: in/securing citizens in early republican Turkey (1923-1946)

(Sage Publications Ltd., 2014-12-19)
The relationship between security and citizenship is more complex than media portrayals based on binary oppositions seem to suggest (included/excluded, security/insecurity), or mainstream approaches to International ...
• #### Security and military balance in the Black Sea region

(Routledge, 2010-09)
This paper analyses the current security challenges and military balance in the Black Sea region. The region, which has been going through vast political and economic transformations since the end of the Cold War, has ...
• #### Security dimension: a clash of security cultures? differences between Turkey and the European Union revisited

(Routledge Taylor & Francis Group, 2010)
• #### Security implications of Turkey’s march towards EU membership

(Palgrave Macmillan, 2006)
Contrary to what many believe, both inside and outside the country, Turkey’s march towards membership in the European Union (EU) may cause serious deficiencies in its security As a country which has traditionally taken a ...
• #### Security in the Arab world and Turkey: differently different

(Routledge, 2012)
The study of security, with its attention to relations of power, constitutes a suitable site for exploring how and why International Relations (IR) has evolved in the way it has outside “core” settings. By focusing on the ...
• #### Security through trust-building in the Euro-Mediterranean cooperation: two perspectives for the partnership

(Routledge, 2010-12)
Trust-building creates puzzles for analysts in relation to what kind of trust is built in world politics, between whom, and to what end. This article studies two types of trust in the Euro-Mediterranean Partnership: ...
• #### The securityness of secularism? The case of Turkey

(Sage Publications Ltd., 2008-12)
Secularism is frequently portrayed as a security referent in present-day Turkey. But, what is it that makes secularism a security issue? Where are we to locate the `securityness' of secularism? Against prevailing accounts ...
• #### Shades of diplomatic recognition: American encounters with Turkey (1923–1937)

(Brill, 2009)
• #### A short history of anti-Americanism and terrorism: the Turkish case

(Oxford University Press, 2002-09)
[No abstract available]
• #### A Short history of anti-americanism and terrorism: The Turkish case

(Temple University Press, 2003)
• #### Signalling in the Turkish-Syrian water conflict

(Sage, 1998)
This paper proposes a simple two-person game of one-sided incomplete information in extensive form to understand strategic choices made in the Turkish-Syrian linkage between water and terrorism. Turkish intelligence ...


text:
### Finding Induced Subgraphs via Minimal Triangulations

Fedor V. Fomin & Yngve Villanger
Potential maximal cliques and minimal separators are combinatorial objects which were introduced and studied in the realm of minimal triangulation problems including Minimum Fill-in and Treewidth. We discover unexpected applications of these notions to the field of moderate exponential algorithms. In particular, we show that given an n-vertex graph G together with its set of potential maximal cliques, and an integer t, it is possible in time the number of potential maximal cliques times $O(n^{O(t)})$...


text:
# A block of mass ‘m’ is connected to two springs of stiffness K1 and K2 as shown in the figure. f1 and f2 are the frequencies of the block when connected to K1 and K2 independently. Then the frequency of ‘m’ when connected to K1 and K2 as in the figure is

1. f = f1 + f2
2. $$f = f_1^2 + f_2^2$$
3. $$f = \sqrt {f_1^2 + f_2^2}$$
4. $$f = \sqrt {f_1^2 - f_2^2}$$

Option 3 : $$f = \sqrt {f_1^2 + f_2^2}$$
Free
SSC JE ME Full Test 4
6011
200 Questions 200 Marks 120 Mins

## Detailed Solution

$$\begin{array}{l} {f_1} = \frac{1}{{2\pi }}\sqrt {\frac{{{k_1}}}{m}} \\ {f_2} = \frac{1}{{2\pi }}\sqrt {\frac{{{k_2}}}{m}} \end{array}$$

f = when spring are in parallel

k = k1 + k2

$$\begin{array}{l} f = \frac{1}{{2\pi }}\sqrt {\frac{{{k_1} + {k_2}}}{m}} \\ \Rightarrow f = \sqrt {f_1^2 + f_2^2} \end{array}$$