kinetics - Unit consistency in rate equations

I suppose that my problem is not one of great profundity, but it is an annoying one. The problem is related to the measurement units involved in rate equations of different order. Not being a chemist myself, I have in my work encountered equations of the type: $$\frac{-\mathrm{d}[A]}{\mathrm{d}t} = k [B]^b [A]^a$$ representing the decay of some species $A$. The brackets denote concentration and $k$ is the rate constant. $B$ is some other chemical species (cooking chemical) and then there are the exponents $a$, $b$. For a first order reaction with $b = 0$ and $a = 1$ everything is still under some kind of control; if time is measured in minutes the unit of the rate constant is $\mathrm{min^{-1}}$.

However, if we have a pseudo first order reaction where the species $B$ is present albeit constant during an experimental run, problems arise. In my line of work the species $B$ is typically hydroxide ions and their concentration is traditionally given in molar, $\mathrm{mol/L}$. Even if the concentration of $B$ does not change, the initial concentration plays a role, hence the power of $[B]$ usually appears as a separate factor in the rate equation. Unfortunately, this complicates the unit balance in the equation as frequently the exponent $b$ is a non-integer number. One workaround would be to rescale the concentration to a dimensionless number, but the choice of scaling parameter would be rather arbitrary. Another, perhaps more elegant solution would be to work with molar fractions, but this would be discordant with most of the literature in the field, where the question of unit consistency mostly is disregarded.

A second order rate equation ($b = 0$, $a = 2$, or $b = 1$, $a = 1$) leads to the unit $\mathrm{L\,mol^{-1}\,min^{-1}}$ for the rate constant. I suppose this is still somehow acceptable, even if I would prefer to work with scaled concentrations (divided by the initial concentrations) with unit $\mathrm{min^{-1}}$ for the rate constant, but for fractional order rate equations there is the same problem as in the earlier described pseudo first order case.

Is there any prescribed remedy to this dilemma?

halacha - Non-Jew's marriage obligation

Does a non-Jew have an obligation to get married like the Jew does?

word choice - What's the difference between なぜ、どうして and なんで when meaning 'why'?

I've been meaning to ask this for a while.

What is the difference between these 3 words. I was taught they all mean "why", but obviously, being different words they convey different nuance and would be used in different situations.

What would be the difference between these 3 sentences and in what situations would they be used?

なぜここにいるのですか？
どうしてここにいるのですか？
なんでここにいるのですか？

organic chemistry - Is a SR2+ substituent really more electron-withdrawing than NH3+?

As the electronegativity of nitrogen and sulfur are around 3.04 and 2.58, respectively (according to the Pauling scale). So according to that, $\ce{NH3+}$ should pull the electrons more towards it than what $\ce{SR2+}$ should. This argument has been put forth by Jan in his answer to a similar question here.

However, my textbook (Organic Chemistry by Subrata Sengupta) states that the exact opposite is true. Who is correct here?

filters - Best way to process this signal

I am novice in signal processing, and i have to aplogise for my english level. The problem is the next:

I work for foundries, in this sector the cast parts are manufactured pouring liquid metal in sand moulds. These moulds are formed by 2 sand semi-moulds (first figure), and these semi-moulds are mafuctured in the DISA machine.

The problem is that sometimes the DISA machine does not work properly and the alignment between semi-mould is not correct. The result of the problem is thar the cast parts lose the symmetry properties and are rejected.

To solve the problem i have been capturing data through a laser device. The laser is placed in a fixed place and is measuring the distance until the semi moulds in a production lien. The semi moulds are manufactured with a cube footprint in the bond of itselves. Like in the image (in the manufacturing chain the gap between semi mould seen in the figure does not exist).

So, the laser measures the front face of the semimould and then the footprint of the cube obtaining the next image:

The upstairs line represent the measurement in the front face of the moulds and the downwords peaks represent the measurements in the cubes footprints.

If we make a zoom in the peaks we see the next.

This image represent the footprint of the cube and the bond of semimoulds (global minimum). The problem is the next, through the procesing of the laser device signal i must try if the semimoulds are correctly aligned or not with a tolerance value uf 0.2mm over this value, the semi moulds are misaligned.

What i am looking for is for methods to process the last images signal and compute the gap between semimoulds. I need algorithms to minimize the noise of the signal in vias of build a model which approximates my signal to the real morphology of the moulds and also need a robust method to calculate the gap between semi moulds with the minimum uncertainly as possible.

If the problem is not sufficiently clear, please ask me!

---

Firstly A_A, thanks for your answear. I think in some way, i have not correctly explain the problem.

As you have say above. This is correct.

  | H |
  | H |
  | H |
=>|   |

  |   |

But there is not distance between semimoulds. In the next image you can see a proptotype of the real system.

But the solution what we are looking for is to measure a gap in the cube footprint created between semimoulds. Such footprint represents the join of the semi moulds. So that, a mould is formed as (left image one semimould, right image two semimoulds forming a mould):

When the laser is measuring inside the cube footprint, we find the "valleys" in above graphics. But the gap we are trying to detect is generated by the shift of one semimould respect to the other. The threshold k is OK it is 0.2mm. The speed of the conveyor is not constant becouse it depends on the pouring machine and the wide of the mould (but we could know it). It is also important that sometimes the conveyor is stopped waiting to the pouring machine. The sample rate is 0.0025 seconds but que device can work with different sampler rates (bigger than 0.0025).

The main problem i have is to determine the gap of 0.2mm in the join of the two semimoulds, which depicts that a semimould is moved respect to the other one. [![enter image description here][6]][6]

And this one represents a mould which is NOK. So througth the laser we are tying to detect if the gap between semimoulds is bigger than 0.2mm (green slot in the image).

The last image of my first post is the laser measurement inside the cube footprint of the moulds. So, i reformulate the question. What is the best way to process this signal to detect if the gap is bigger than 0.2mm.

I hope it will be more explainatory.

[EDITED VERSION]

I list the main problem i thin what i will have once i have separate the signal into wave fronts.

First, i see 3 problems. Once separated into the sets which contains the values which belong to the cube footprints in the sand moulds (the cubes in the join of semimoulds).

• 
  

  How i can remove the signal noise produced by the vibrations of the DISA machine (the variability seen in the third image). I would like to get preprocess the signal in order to get the most similar signal to the real one.

  
  


• 
  

  Through which algorthm can i calculate the gap between semimoulds?

  
  
  


• How i can infer the angle between semimoulds?

Here is the link to download th Data

Two more images to explain the "gap" what i want to calculate.

This image depicts the conveyor (i have not draw the cube footprints in the image to make it simpler). We assume that the conveyor is moving the moulds to the right.

Representation of the real production line.

Thanks!

torah study - What is the importance of Chiddush?

I have long taken for granted that it is important to be m'chadesh chiddush (compose new and novel torah insights). However, I realize I have no source for that notion. Is there any source which indicates that it is important to try to come up with chiddushim, or perhaps is simply studying torah without adding any novel interpretation equally as meritorious?

tefilla - Facing east when standing in prayers

I was praying with my kid in a synagogue wherein the aron was against the eastern wall, and most of the seats were facing north or south. My kid wondered why the people around us turned to face east whenever they were standing. I had (and have) no idea. (Of course, they face east for the amida and so on. But then also for "Alenu" and shir shel yom and kadish (even those not saying it) et cetera.) Anyone know?

translation - What does 鏡越し mean in this sentence?

I encountered the word 「鏡越し」 while I'm reading a web novel, titled 『とある殉教者の訃報』by 鼠色猫／長月達平

Here is the full sentence.

「もし、これが鏡越しの会話じゃなかったら、今頃、君はバラバラだったよ。そうならなかったことを、僕に感謝した方がいいんじゃないかな」

I googled 「鏡越し」 and still I couldn't find the meaning of this word. The closet meaning I got when I used google translate was "Glanced up from glasses" and I don't think it is the right translation for this sentence. How should it be translated? Thank you in advance for your help.

Answer

Sounds like "through the looking glass" or "through the mirror". (Which I think may refers to an alternate world/universe/timeline used as a metaphor to illustrate what the present time might have been under different circumstances)

Unless if it happens that in the setting of the story the mirror is a plot device for actually going into an alternate world or communicating to the alternate world (or going/communicating to somewhere else within the same world) then it's not a metaphor.

meaning - What does といった mean?

I started to read The Alchemist (both in Japanese and English) and I'm not able to understand the meaning of といった in this sentence: 少年の名はサンチャゴといった。 The equivalent of that sentence in the English version is "The boy's name was Santiago".

kaddish - Siyum Masechta Ketana

When I celebrate my completion of a minor tractate (e.g. Masechet Derech Eretz or Kutim or Gerim), should I say Hadran and/or Kaddish at my Siyyum (party)?

Answer

Rabbi Yechezkel Moskowitz answers that one may make a full "Siyum" on all "Masechtos Ketanos", except for Maseches Derech Eretz (he quotes the Sefer Yoma Tava, Sha'ar 1, Page 23).

For the exception of Maseches Derech Eretz, he notes the Maharsham to OC 551:10 (image below), which states clearly in the name of the Peri Megadim (Mishbetzos Zahav) and Bach that it is not considered Torah for certain other Halachos:

This ruling (that one may make a Siyum on a Masechta Ketanah, although he doesn't mention the exception of Derech Eretz) is also stated clearly by the Alei Tamar in his intro to Bava Kama, as well as in Pesachim Perek 10 (text quoted here).

This article also confirms that a classic "siyum" may be made on these Masechtos, in the name of Rav Ovadiah in Yabia Omer 1:26:10, but I haven't looked that up.

minhag - Why is the day of Rosh Chodesh announced before every month except Tishrei?

Why is Tishrei the only month not included in the custom of announcing the day(s) of Rosh Chodesh on the Shabbos before the month begins?

halacha - May a 3 sided pyramid (almost) be used as a succah?

Talmud succah states that a succah must have a minimum of 3 sides. Can a person build a 3-sided pyramid, but rather than a "full" pyramid, where all the sides meet at the same point at the top, let's say, there's a small triangle (say 9 square inches in area) on top and schach is placed there. Is this permitted?

Two possible problems, perhaps:

• Do all the walls need to be perpendicular to the ground?


• What is the minimal area required for a valid roof for the succah? Is 9 sq. in. too small?

product recommendation - Is there a book which gives a good background understanding to Isaiah's prophecies?

I am trying to learn the book of the prophet Yeshaya (Isaiah). I am finding the early (unfamiliar) chapters very difficult. Rashi’s commentary does not help me enough. Is there a book which gives a good background understanding to the prophecies?

conjugations - ～うございます - keigo い-adjectives

I'm not sure if this is actual keigo, or just a polite form of adjectives. Anyway, there are several that we're all familiar with that are still used today.

• はやい　→　おはようございます


• ありがたい　→　ありがとうございます


• めでたい　→　おめでとうございます

There are a couple of others I've seen in textbooks at some point as well:

• たのしい　→　たのしゅうございます


• おいしい　→　おいしゅうございます.

I know that I've seen different rules for how to form these depending on the ending. We can see that the first three end in 〜ai that it becomes 〜ou gozaimasu, and the two 〜shii ones become 〜shuu gozaimasu.

However, I don't know the hard rules about how to form them based on their endings. Furthermore, I'm even more confused about when to add the starting お (はやい adds it, but ありがたい doesn't).

I know these forms aren't used much these days (except "set" phrases like the first three), but it's a piece of knowledge that has eluded me over the years.

Answer

I will answer the two questions separately.

How to make the form of i-adjectives before ございます

Grammatically はよう, ありがとう, めでとう, たのしゅう, おいしゅう in these examples are called ウ音便 (うおんびん) of はやく, ありがたく, めでたく, たのしく, おいしく, respectively. 音便 (おんびん) means the form modified for easy pronunciation.

The actual form of ウ音便 of an i-adjective depends on the vowel before く in the -く form (or equivalently, the vowel before い in the dictionary form).

• If the vowel is -a, ウ音便 is -ou: はやく→はよう, ありがたく→ありがとう, めでたく→めでとう. This -ou is pronounced as a long vowel /oː/.


• If the vowel is -i, ウ音便 is -yuu: たのしく→たのしゅう, おいしく→おいしゅう.



• If the vowel is -u, ウ音便 is -uu: さむく→さむう.


• (If the vowel is -e, ウ音便 should be -you, pronounced as a long vowel /joː/, but see below.)


• If the vowel is -o, ウ音便 is -ou: おそく→おそう. This -ou is also pronounced as a long vowel /oː/.

(I could not think of any i-adjective whose dictionary form ends with -ei, and the only adjective of this form in EDICT is 執念い (しゅうねい), which I had never heard of. The pattern above is estimated from the discussion below.)

These forms of ウ音便 are the result of two sound changes.

• In the first step, く was replaced by う: はやく→はやう, たのしく→たのしう, さむく→さむう, おそく→おそう.


• In the second step, the -au became -ou and the -iu became -yuu: はやう→はよう, たのしう→たのしゅう. (This sound change is not limited to ウ音便 of i-adjectives, and in other words, -eu became -you with pronunciation /joː/. This is why I wrote the ウ音便 of i-adjectives ending with -ei should be -you.)

Why sometimes with the prefix お and sometimes without お?

I can explain this only partly.

The prefix お shows respect. おはようございます literally means “You are early,” and おめでとうございます literally means “(what happened to you) calls for celebration.” In these cases, the adjectives describe something about “you,” hence the prefix お. On the other hand, in the sentence たのしゅうございます “I have fun,” the adjective たのしい describes the state of “me,” hence no prefix お.

However, this argument suggests ありがとうございます should have the prefix お because it literally means “What you did is hard to exist,” and the subject of ありがたい is the action of “you.” I do not know any explanation why ありがとうございます is not おありがとうございます.

colloquial language - I have some question about てけない

僕独りじゃ生きてけない

I saw this sentence, but, I actually get the meaning. It means "I can't live alone" right? But how do you translate it? What is "けない" grammar?

I tried to search a lot of websites, but I couldn't find any information about it.

Also, what is this じゃ？ I've never seen a sentence like this before. 教えてください！

computational chemistry - Definition of the B3LYP functional in common QC programs

I wanted to use custom functionals with Gaussian and came up with some interesting definitions of the B3LYP functional within Gaussian, Orca and Turbomole, ...

$$\small\begin{array}{lcccccc} \hline & \text{Gaussian} & \text{ORCA} & \text{Turbomole} & \text{NWChem} & \text{Molpro} & \text{GAMESS(US)}\\ \hline \text{HF} & 0.2 & 0.2 & 0.2 & 0.2 & 0.2 & 0.2\\ \text{Slater} & 0.8 & 0.8 & 0.8 & 0.8 & \color{red}{0.08} & 0.8\\ \text{Becke} & 0.72 & 0.72 & 0.72 & 0.72 & 0.72 & 0.72\\ \text{VWN-x} & {\color{red}1} & {\color{red}{1}} & 0.19 & 0.19 & 0.19 & 0.19\\ \text{LYP} & 0.81 & 0.81 & 0.81 & 0.81 & 0.81 & 0.81\\ \hline \end{array}$$

It seems to be clear, that all programs define it somehow similar, but there are also some points that made me curious about the definitions. Let's start with the overall structure of this functional:

$$\text{XC-Functional}=a E_x^\text{local}+(1-a)E_x^\text{HF}+b E_x^\text{non-local}+c E_c^\text{non-local}+(1-c) E_c^\text{local}$$

The Gaussian documentation for DFT inputs specifies how one could change the amounts of each "sub-functional" by using the IOp-Statements through:

IOp(3/76=mmmmmnnnnn) IOp(3/77=mmmmmnnnnn) IOp(3/78=mmmmmnnnnn)

Where mmmmm and nnnnn will get divided by 10000 and 3/76=$P_1P_2$, 3/77=$P_3P_4$ and 3/88=$P_5P_6$. Those $P_{1,..,6}$ values are part of the following equation, which is a modified version of the equation above.

$$\text{XC-Functional}=P_2 E_X^\text{HF} + P_1 \left(P_4 E_X^\text{Slater} + P_3\Delta E_x^\text{non-local}\right) + P_6 E_C^\text{local} + P_5 \Delta E_C^\text{non-local}$$

Combining both, this yields: $P_1 = \{1,0\}$, $P_2 = 1-a$, $P_3 = b$, $P_4 = a$, $P_5 = c$ and $P_6 = 1-c$.

---

Now looking at Gaussian and ORCA, they both use 100% VWN and 81% of LYP, which should actually be combined to give 100% (instead of 181%) as is done by all other mentioned programs through using 19% VWN and 81% LYP.

It seems, that I am lacking some important information to understand that definitions in both, Gaussian and ORCA, and I hope seriously, that someone can enlighten me.

---

PS My discussion with Martin came up with the possibility, namely that there might be some missing brackets in the second equation, giving the following:

$$\text{XC-Functional}=P_2 E_X^\text{HF} + P_1 \left(P_4 E_X^\text{Slater} + P_3\Delta E_x^\text{non-local}\right) + P_6 \mathbf{{\color{red}(}}(1-P_5)E_C^\text{local} + P_5 \Delta E_C^\text{non-local}\mathbf{{\color{red})}}$$

---

Appendix: Information from the program output or the documentary

• 
  

  Gaussian 09 Rev. A.02 output

  
  

  IExCor=  402 DFT=T Ex=B+HF Corr=LYP ExCW=0 ScaHFX=  0.200000
  ScaDFX=  0.800000  0.720000  1.000000  0.810000
  



• 
  
  

  ORCA 3.0.3 output

  
  

  Fraction HF Exchange ScalHFX         ....  0.200000
  Scaling of DF-GGA-X  ScalDFX         ....  0.720000
  Scaling of DF-GGA-C  ScalDFC         ....  0.810000
  Scaling of DF-LDA-C  ScalLDAC        ....  1.000000
  Perturbative correction              ....  0.000000
  NL short-range parameter             ....  4.800000
  



• 
  

  Turbomole 7 define

  
  
  

   b3-lyp          | HYB  | 0.8S+0.72B88   | 0.19VWN(V)     | 1-3,5,6,10
                   |      | +0.2HF         | +0.81LYP       |
   b3-lyp_Gaussian | HYB  | 0.8S+0.72B88   | 0.19VWN(III)   | 1-3,5,6,10
                   |      | +0.2HF         | +0.81LYP       |
  



• NWChem


• 
  

  Molpro

  
  

  B3LYP   EXACT:B88:DIRAC:LYP:VWN5    0.2:0.72:0.08:0.81:0.19
  

  
  
  

  the 0.08 is probably a typo

  
  


• GAMESS(US)

grammar - How to translate て-form + ろ

In the Japanese exclamation:

待ってろよ！

What function does ろ have and how should it be translated to English? I've searched everywhere, but I can't seem to find a decent explanation. The only thing that came close was a website telling me that the て-form could sometimes be replaced by a ろ, but that's not what's happening here..

Answer

This is a shortening of 待っていろ which is imperative for 待っている　(いろ being the imperative of いる)

separability - Fast/efficient way to decompose separable integer 2D filter coefficients

I would like to be able to quickly determine whether a given 2D kernel of integer coefficients is separable into two 1D kernels with integer coefficients. E.g.

 2   3   2
 4   6   4
 2   3   2

is separable into

 2   3   2

and

 1
 2
 1

The actual test for separability seems to be fairly straightforward using integer arithmetic, but the decomposition into 1D filters with integer coefficients is proving to be a more difficult problem. The difficulty seems to lie in the fact that ratios between rows or columns may be non-integer (rational fractions), e.g. in the above example we have ratios of 2, 1/2, 3/2 and 2/3.

I don't really want to use a heavy duty approach like SVD because (a) it's relatively computationally expensive for my needs and (b) it still doesn't necessarily help to determine integer coefficients.

Any ideas ?

---

FURTHER INFORMATION

Coefficients may be positive, negative or zero, and there may be pathological cases where the sum of either or both 1D vectors is zero, e.g.

-1   2  -1
 0   0   0
 1  -2   1

is separable into

 1  -2   1

and

-1
 0
 1

Answer

I have taken @Phonon's answer and modified it somewhat so that it uses the GCD approach on just the top row and left column, rather than on row/column sums. This seems to handle pathological cases a little better. It can still fail if the top row or left column are all zeroes, but these cases can be checked for prior to applying this method.

function [X, Y, valid] = separate(M)    % separate 2D kernel M into X and Y vectors 
  X = M(1, :);                          % init X = top row of M
  Y = M(:, 1);                          % init Y = left column of M

  nx = numel(X);                        % nx = no of columns in M
  ny = numel(Y);                        % ny = no of rows in M
  gx = X(1);                            % gx = GCD of top row
  for i = 2:nx
    gx = gcd(gx, X(i));
  end
  gy = Y(1);                            % gy = GCD of left column
  for i = 2:ny
    gy = gcd(gy, Y(i));
  end

  X = X / gx;                           % scale X by GCD of X
  Y = Y / gy;                           % scale Y by GCD of Y
  scale = M(1, 1) / (X(1) * Y(1));      % calculate scale factor
  X = X * scale;                        % apply scale factor to X
  valid = all(all((M == Y * X)));       % result valid if we get back our original M
end

Many thanks to @Phonon and @Jason R for the original ideas for this.

halacha - Permissibility of Prayer in a Sabbatean Synagogue

Inspired by the Churva Synagogue of R. Yehuda HaChassid (18th cent.) who was likely a Sabbatean (not to be confused with the 12th century rabbi of the same name), and his congregation which almost certainly included Sabbateans, I ask whether it is permitted to pray in a Sabbatean synagogue.

This in light of the fact that Sabbatean ideology included seemingly idolatrous elements.

---

I recognize that the Churva Synagogue in particular has been destroyed (hence the name) and subsequently rebuilt, and thus likely lost whatever its original legal status was. However, this was just the inspiration for the question. The question is not asking about the Churva in particular, but rather about Sabbatan sites in general.

christianity - Can I still wear my Star of David?

My mother is Jewish but my father is Christian and I was raised in the Christian church, but I still have a lot of respect for my Jewish heritage. Would it be wrong to wear a Star of David necklace, or would that offend people?

hashkafah philosophy - Why Wait for Moshiach according to the Rambam

The Rambam in Hilchos Yesodei HaTorah says God has no joy or sadness. If so, why do we wait for moshiach? For G-d's glory? G-d does not need anything from us.

Answer

Rambam himself states why great Jews wait for mashiach, in Hilkhot Melakhim (12:7):

לא נתאוו הנביאים והחכמים ימות המשיח--לא כדי שישלטו על כל העולם, ולא כדי שירדו בגויים, ולא כדי שינשאו אותם העמים, ולא כדי לאכול ולשתות ולשמוח: אלא כדי שיהיו פנויין בתורה וחכמתה, ולא יהיה להם נוגש ומבטל, כדי שיזכו לחיי העולם הבא, כמו שביארנו בהלכות תשובה

The prophets and the wise men only desired the messianic age...So that they be free [to pursue] Torah and its wisdom. (My translation of the bolded portion).

Rambam avoids the question entirely, by not saying that the waiting is for God's sake, but for our sake.

coordination compounds - Why is Ni[(PPh₃)₂Cl₂] tetrahedral?

Since PPh₃ is strong field ligand and, the famous Wilkinson's catalyst, which also possess this ligand is square planar, then what makes the above complex tetrahedral?

acid base - Determining the pH of an organic solvent

Our work is faced with the issue of determining the charge of compounds that are dissolved in chloroform. One could realistically determine the charge of the relevant moieties knowing the $\mathrm{p}K_\mathrm{a}$ of those groups. However,

• How would you determine or calculate the $\mathrm{pH}$ of an organic solvent?

An alternative way of asking this question is how would one calculate the concentration of hydronium ions or free protons in a nonaqueous solution.

Answer

I'm not sure why you're wanting to exert so much effort to find the charge of compounds.

If you really want to know the charge, determine it more directly. Electrophoresis can allow you to do so. A charged species is put in a capillary tube that is in between a cathode an an anode. When a charged species is subjected to an electric field, it will experience a force proportional to its charge and the field strength.

Drag forces present in the solvent are also a consideration in this setup and they depend on the "size" of your ion as well as viscosity of your solvent. One also has to worry about Joule heating, as an increase in temperature will cause poor reproducibility. Picking a suitable detector is fun, but hopefully you can get by with the common UV-vis detector.

So if you can find a suitable setup, know the radius of your ion and know the time between injection of your sample and its arrival at a detector, you can at least determine its effective charge.

halacha - May the Sotah take the bitter waters intravenously?

In Naso, we read (Bamidbar 5:32) that the kohen blots out the curses (which include Hashem's name) in the bitter waters and then gives for the woman to drink (5:24).

What if the woman is unable to swallow the waters due to their bitterness?Could she instead take it as an intravenous injection? Or do we insist that she swallow it?

parshanut torah comment - difference between תולעים and רמה

In Beshalach 16:20:

וְלֹא שָׁמְעוּ אֶל מֹשֶׁה וַיּוֹתִרוּ אֲנָשִׁים מִמֶּנּוּ עַד בֹּקֶר וַיָּרֻם תּוֹלָעִים וַיִּבְאַשׁ וַיִּקְצֹף עֲלֵהֶם מֹשֶׁה:‏

A few Pesukim later in 16:24:

וַיַּנִּיחוּ אֹתוֹ עַד הַבֹּקֶר כַּאֲשֶׁר צִוָּה מֹשֶׁה וְלֹא הִבְאִישׁ וְרִמָּה לֹא הָיְתָה בּוֹ

What's the difference and why the difference between תּוֹלָעִים and רִמָּה?

halacha - Can the descendants of a mamzer ever become full Jews?

Is there any way for the descendants of a mamzer to ever become Jews with full rights, or are they stuck with mamzerus forever? For example, if a man who is a mamzer marries a non-Jew, and then their children convert to Judaism, are the children mamzerim?

Answer

As discussed previously:

1800 years ago, it sounds like the Mishnah would permit a mamzer to marry a non-Jewish (actually, more like quasi-Jewish) slave woman; when that woman is freed she (and her unborn children) become full Jews. A (male) mamzer would thus be allowed to father a non-mamzer child this way.

In contemporary times you can't just go out and buy a quasi-Jewish slave woman (at least not legally in the US; and we don't condone breaking the law). One suggestion has been to find a woman interested in converting to Judaism, but instead of going through full conversion, declare it "conversion to quasi-Jewish slave status"; many rabbis feel this doesn't work as there is no such thing in our location and age.

If a mamzer married a non-Jewish woman, and she and the children then converted, the child(ren) would not be labeled a mamzer, though we generally don't allow a Jewish man to go marry a non-Jewish woman (even if she has plans to later convert). There are rumors that certain rabbis have actually recommended this in certain cases, though. (Again, ask your local rabbi!)

Lastly, Rabbi Moshe Feinstein had the fascinating opinion that mamzer status is transmitted only through normal procreation; a mamzer could choose to marry a normal Jewess and have children only via artificial insemination. I don't think Rabbi Feinstein's opinion on this is commonly accepted. (As heard from a yutorah shiur by Rabbi Willig.)

beis hamikdash - Will firstborn sons or Kohanim serve in the Third Temple?

In Ezekiel 48, where he prophesied about a future temple, he talks about Kohanim and Levites serving. "Kohanim of the sons of Zadok..." or "Now for the Levites, opposite the border of the Kohanim..." and so on. However I have heard (don't remember where) that firstborn males are supposed to be the ones to serve in the Third Temple. So who will serve, the Kohanim and Levites, or the firstborn?

halacha - What should a woman who can only do Chalitza do if her Yevam can't do it?

In some cases of Zikas Yibum, there is a Rabbinic prohibition against their doing Yibum (eg. the deceased husband's brother is a Mamzer, cf. Shulchan Aruch Even Haezer 174) and as such they must perform Chalitza.

What if in such a case all the brothers could not perform Chalitza for practical reasons (eg. none of them have legs, cf. Shulchan Aruch Even Haezer 169).
Could the brother who's a mamzer do Yibbum (according to sefardim who allow Yibbum and even according to Ashkenazim as there is no option of chalitza) or would she be left an aguna?

ions - Can metals have a net negative charge

Normal metals like sodium or Calcium have a positive charge as $\ce{Na}^+$ or $\ce{Ca}^{2+}$. Transition metals have a loot of variable oxidation states.

Yesterday I read about Iridium in Wikipedia and it stated that

a +9 oxidation state has been found in $\ce{IrO_4^+}$

which is astounding for me...

So i was thinking can metals have a net negative charged ion also?

According to Google :

Since it is written that metals USUALLY have positive charges which means there may be conditions or compounds when they have negative charges too. Is it possible?

Also can Noble gasses form ions too?

Answer

These species usually do not exist in nature, but they can be synthesized.

1. Silver has been reduced in liquid ammonia to give $\ce{Ag-}$.



2. A lot of anionic metal carbonyl complexes $\ce{M(CO)_{n}^{m-}}$ have been synthesized:

-1

• $\ce{[V(CO)6]-}$, $\ce{[Nb(CO)6]-}$, $\ce{[Ta(CO)6]-}$, $\ce{[Mn(CO)5]-}$, $\ce{[Ir(CO)4]-}$, $\ce{[Co(CO)4]-}$, $\ce{[Rh(CO)4]-}$

-2

• $\ce{[Ti(CO)6]^{2-}}$, $\ce{[Zr(CO)6]^{2-}}$, $\ce{[Hf(CO)6]^{2-}}$, $\ce{[Fe(CO)4]^{2-}}$, $\ce{[Ru(CO)4]^{2-}}$, $\ce{[Os(CO)4]^{2-}}$

-3

• $\ce{[V(CO)5]^{3-}}$, $\ce{[Nb(CO)5]^{3-}}$, $\ce{[Ta(CO)5]^{3-}}$, $\ce{[Mn(CO)4]^{3-}}$, $\ce{[Re(CO)4]^{3-}}$

-4

• $\ce{[Cr(CO)4]^{4-}}$, $\ce{[Mo(CO)4]^{4-}}$

There's a review by John E. Ellis: Highly Reduced Metal Carbonyl Anions: Synthesis, Characteri's zation, and Chemical Properties on these compounds.

---

Edit

While Christian Aichinger's comment concerning $\pi$-backbonding in metal carbonyls is correct, it is important to realize that $\ce{CO}$ is a neutral ligand!

With other words: The Mond process: $\ce{Ni(s) + 4CO -> Ni(CO)4}$, using nickel powder and carbon monoxide, is not a redox reaction and the oxidation state of the metal still is $0$ in the metal carbonyl.

number - Echad Va-arba'im Ushlosh Meyot?

Who knows three hundred forty one?

אחד וארבעים ושלוש מאות - מי יודע?‏

The traditional Passover song "Echad" implies a possible presupposition that there is a Jewish significance to be found for each natural number. Accordingly, there is an ongoing series on Mi Yodeya that is attempting to unearth significant Judaism facts about each number, in sequence.

What significant Judaism facts are there about the number 341? The more significant within Judaism and the more intrinsically dependent on the value 341, the stronger the answer. Please include sources for your information wherever possible, as with all other answers on this site.

Maybe lazy gematria is a good thing, or maybe you should stay away from it like you do from fire, knowing that if your answer last night was lazy gematria, your burden today and into the future will be guilt. Please don't base your answer on it.

Answer

According to Sefer Ezra, when the Jewish nation returned to Eretz Yisrael for the second Bais HaMikdash, 4289 Kohanim returned (2:36-39), while only 341 Leviyim returned (2:40-42).

Hat-tip: Sefer ראיות מכריעות נגד ולהויזן - הופמן, דוד צבי בן משה.

word choice - What are the differences between 帰る and 戻る?

Can you give an example of when 帰る should be used instead of 戻る, and vice versa?

The reason I ask is that I sometimes get corrected when using the two, such as in:

×　そのとき私は日本から戻ってきて、大学に戻って入りました。 (ignore the other problems with this ☺)
○　そのとき私は日本から帰ってきて、大学に戻りました。

Answer

Examples would be

• 
  
  

  仕事に戻る。(go back to work from appointment or something)

  
  


• 
  

  家に帰る。(go back to home, (when there is no plan in mind to go back to same place for today))

  
  


• 
  

  財布忘れたので家に一旦戻る。（Forgot the wallet and go back to home once (need to go back same route again)）

  
  

etymology - What are some examples of Jewish names?

What are Jewish sounding names that come from various occupations and locations? Please give the "rough" translation and background too.

Answer

The following links may be of interest:

frequency spectrum - Why is the bandwidth doubled with AM?

Let's say I have an arbitrary signal which has the following frequency spectrum and a bandwidth of BNF:

Now I use Amplitude Modulation to transport the signal. The frequency spectrum will change accordingly:

Now I know that the required bandwidth doubles. I don't understand where the doubled bandwidth applies as I can't transport negative frequencies.

MATLAB, How to filter a discrete signal?

I have a 1-by-10000 matrix of double`s stored in a file named "fecg.mat". The matrix represents the magnitude of a recorded FECG signal.

I've plotted it against time (from 0 to 9999):

For removing the baseline I wonder if I can use a high-pass filter. How do I design a proper filter?

P.S Signal processing isn't my field of study. I have no idea how to filter a discrete time-domain signal.

organic chemistry - What are the steps to creating synthetic glucose?

I need to know how to go about creating synthetic glucose with generally available materials. As I am aware of both photosynthesis and glucose in nature, I will not need lessons in how plants produce it. So, how may glucose be produced by artificial means?

experimental chemistry - Why is the outermost part of the Bunsen burner flame not the hottest region?

Why is the blue flame the hottest on a Bunsen burner?

I thought the outermost part of the flame must be the hottest region because of complete combustion of gases taking place there. Where am I getting wrong?

verbs - Conjunctive form (e.g. 書き) vs Conj + mono (e.g. 書き物)

I'm trying to fully understand the plain conjunctive form without a suffix. I've seen it mainly in the form of 話, where it means a talk or speech. So I think it means something along the lines of "the thing that is produced when someone speaks for a bit". So applying that logic to a verb like 書く. Would 書き be a thing that is produced when someone writes for a bit, i.e. a document? Is it a synonym for 書き物 then, or does it mean something subtly different? Or is it even a proper word?

Mainly I'm just trying to get a better understanding of the plain conjunctive form, and how to apply it to a wider range of verbs. The resources I'm studying from only cover it very briefly, and only give a few examples (話 usually being one of them).

Answer

Verb stem (masu-stem) as a noun can have various meanings depending on the original verb, and you may not be able to determine its meaning without referring to a dictionary. I generally recommend you memorize these, and avoid "coining" a new word unless you're really comfortable with Japanese.

• Person who does the action (≒ -er/-or)
  
  
  
  • 酔っ払い drunkard
  
  
  • のぞき peeper
  
  
  
  • ヴァイオリン弾き violin player
  
  
  
  


• The action itself (≒ -ing)
  
  
  
  • 走り run
  
  
  • 支払い payment
  
  
  
  


• Tool/device to do the action (≒ -er/-or)
  
  
  
  
  • つまみ knob, tab
  
  
  • はかり (weight) scale
  
  
  • 引き出し drawer
  
  
  
  


• Something resulting from the action, something associated with the action.
  
  
  
  • のぼり uphill (slope)
  
  
  • のぼり (storefront) banner
  
  
  
  • おのぼり
  
  
  • たたき tataki
  
  
  • 握り nigiri (sushi)
  
  
  • 吹き出し balloon (in manga)
  
  
  
  

Some nouns in this form can have more than one meaning depending on the context. For example, "殺し" can mean "murderer", "killer (weapon)", "killing (move)" or "murder case".

masu-stem + もの generally means "thing to [verb]", but again, lots of nouns in this form have derivative meanings which are difficult to guess, so you need to memorize.

• 出しもの event, attraction


• 入れもの container, box


• 着物 kimono


• 吸いもの suimono


• 見もの something worth seeing, spectacle


• 引き出物 wedding favor


• 吹き出物 pimple

Don't try to create a new one; for example 走りもの and 聞きもの would mean nothing.

A few words have both masu-stem and masu-stem + もの forms, and there is usually a drastic difference between the two:

• 書き (writing skill) vs 書きもの (writing job/task/material)


• 巻き (curl, hurry) vs 巻きもの (scroll (of paper))


• 飲み (drinking party) vs 飲みもの (beverage)


• 笑い (laughter) vs 笑いもの (laughingstock)


• 生き (liveliness) vs 生きもの (living things, animal)


• 考え (idea, thoughts) vs 考えもの (thing worth rethinking, problem)

vsepr theory - Bond character and bond angles

Somewhere along the line of researching why the $\ce{Cl-C-H}$ bond angle in methyl chloride is less than what is predicted ($\pu{109.5^\circ}$), I ran into a book which said that the electron withdrawing effects of the chlorine atom gave the $\ce{C-Cl}$ bond more "p-character".

What does this mean? Is he simply using this term to describe the elongated nature of the bond - i.e. s-orbitals are spherical and p-orbitals not spherical but rather elongated (at least as depicted by cartoon drawings in textbooks)?

Is the author saying that the electron-withdrawing effects of chlorine cause the electrons to spend more time further away from the nucleus; hence the "p-character"? I understand that in a spherical shell, electrons are basically equidistant from the nucleus. But in an elongated, "p-character" shell, electrons can go further away from the nucleus.

Answer

S orbitals are lower in energy than P orbitals. Electrons prefer to be in as low an energy orbital as possible. Therefor, when we mix S and P orbitals to make hybrid orbitals, the more S character the orbital has the lower the energy of electrons occupying that orbital. Let me use chloroform, $\ce{CHCl3}$, as an example to make my point (I have data for it and the $\ce{C-Cl}$ bonds are analogous to those in methyl chloride). The chlorine atom is electronegative, so electrons in the $\ce{C-Cl}$ bond will spend more of their time closer to chlorine - away from the carbon, then they would in say a $\ce{C-H}$ bond. So if the electron density in the hybrid orbital contributed by carbon to the $\ce{C-Cl}$ bond is going to be reduced, why put as much S character in it? Instead save that S character for other hybrid orbitals emanating from the carbon that have higher electron density in them. It turns out in the case of chloroform, knowing the various bond angles and the $\ce{C_{3V}}$ symmetry of the molecule, that the carbon portion of the $\ce{C-Cl}$ has a hybridization of about $\ce{sp^4}$ (more P character and less S character just as we predicted since it has a lower electron density) and the $\ce{C-H}$ bonds are approximately $\ce{sp^{2.75}}$ (using that S character we saved from the $\ce{C-Cl}$ bond to stabilize the electrons in these 3 orbitals, just as we predicted). The same effects play out in methyl chloride, just not as dramatically (e.g. the hybridization index of the $\ce{C-Cl}$ bond will be greater than 3 but less than 4).

What is the underlying concept behind Bandpass sampling?

Can you suggest me some books/webpages on Bandpass sampling?

I undestand that if the signal is restricted between $f_L$ and $f_H$, then the minimum bandwidth required is $2(f_H - f_L)$. But say the centre frequency is in GHz and the bandwidth is in MHz, then by this theory I would have the sampling frequency to be in a few MHz. So in case of GHz centre frequency signal(say 1 GHz), I collect the samples every microsecond. But the signal is changing every nanosecond. I did not understand this concept.

thermodynamics - Entropy Change for mixing water at two different temperatures

Assume that the heat capacity of water is independent of the temperature. Calculate the net entropy change when 1 mole of water at 0 degrees Celsius is mixed with 1 mole of water at 100 degrees Celsius. Assume that the heat capacity of water is (4.184 J/(K-g))(18 g/mol) = 75.3 J/(K-mol) and that the heat capacity of the calorimeter is negligible.

I was wondering if the following general methodology of my attempt was correct.

In attempting to solve this, I first found that the equilibrium temperature was (273+373)/2 = 323 K.

Then, I calculated the entropy by using the equation S = (heat capacity)*ln(T_eq/T_initial) for both 0 degrees and 100 degrees.

Afterwards, I added the two values for entropy and obtained 1.827 J/(mol-K) as the answer.

.

halacha - Learning History on Shabbos

Is there a Halachic problem to read and or learn the topic of History on Shabbos for enjoyment purposes? and why?

infinite impulse response - How does MATLAB handle IIR filters?

MATLAB has a butter, which constructs a Butterworth filter given an order and relative cutoff frequency. The filter created can be used to filter any finite signal.

How does MATLAB do this if the filter has an infinite impulse response? I suppose it must window the signal -- is this done by a simple rectangular window so that all known values are used?

Also, how is the continuous filter discretized? Bilinear transform, impulse response matching, etc?

I don't think the MATLAB help text explains this:

Y = FILTER(B,A,X) filters the data in vector X with the filter described by vectors A and B to create the filtered data Y. The filter is a "Direct Form II Transposed" implementation of the standard difference equation:

a(1)*y(n) = b(1)*x(n) + b(2)*x(n-1) + ... + b(nb+1)*x(n-nb)
                      - a(2)*y(n-1) - ... - a(na+1)*y(n-na)

Answer

This isn't really a MATLAB-specific issue; I see a couple more general questions:

How do you implement a digital IIR filter?

You can apply any general digital filter by convolving its impulse response with the signal that you want to filter. That looks like:

$$ y[n] = \sum_{k=0}^{N-1} x[k] h[n-k] $$

This works great for FIR filters, but you run into complications with IIR systems, because their impulse responses are infinitely long ($N \rightarrow \infty$ in the above sum). That makes the filter output difficult to calculate using the straightforward convolution sum above. To actually implement an IIR filter, we need a way to express the filter output in a way that is more computationally tractable.

The attribute of an IIR filter that makes its impulse response infinitely long is the system's recursive nature; there is feedback from the output back to the filter input. This means that the output of an IIR filter at any given instant of time can depend upon two separate information sources:

• 
  

  The input signal to the filter, past and present, and

  
  


• 
  

  Past values of the filter output signal.

  
  

This leads to the difference equation representation of the IIR system:

$$ a_0 y[n] = \sum_{k=1}^{M-1} a_k y[n-k] + \sum_{k=0}^{N-1} b_k x[n-k] $$

This representation illustrates that we can implement an IIR filter by calculating a weighted sum of $M$ past outputs of the filter and $N$ past inputs of the filter (in practice, $N$ and $M$ could and often are the same; the order of the filter when defined as above is $max(M,N) - 1$). This is a closed-form expression that captures the behavior of the filter fully, suitable for automated implementation, and is the equation referenced in the MATLAB help excerpt that you showed in your question. Note that $a_0$ is almost exclusively assumed to be equal to $1$; I only included it because it is shown in the quoted help text, referenced as a(1).

So to specifically answer your question, as the text suggests, MATLAB implements IIR systems using the above equation. When you design an IIR filter with MATLAB or otherwise, you get two sets of coefficients ($a_k$ and $b_k$ in the difference equation) that define how to weight past filter inputs and outputs in the filter implementation. There are some other subtleties that are sometimes relevant; for instance, the text refers to using a "direct-form II transposed" realization of the filter. You then apply the filter by calculating the difference equation above for each desired output sample.

There are in fact a number of topologies that can be used to implement digital filters, each with their own tradeoffs. DF2T is often used because of its more efficient structure (it contains a minimum number of delay elements) and its improved robustness to roundoff error (since the feedforward coefficients $b_k$ are implemented first).

How does MATLAB design Butterworth filters?

The documentation for the butter function does not specify how it generates the discrete approximation to the analog Butterworth filter prototype. However, by peeking into butter.m, you find:

% step 5: Use Bilinear transformation to find discrete equivalent:
if ~analog,
    [a,b,c,d] = bilinear(a,b,c,d,fs);

end

So it seems that it uses the bilinear transform to map the Butterworth filter prototype to a digital filter realization.

organic chemistry - When is the carbaldehyde suffix correct?

Is benzene carbaldehyde a correct name for Benzaldehyde? I'm (always) getting confused between common and IUPAC names. If the above name is correct then is it a common one or IUPAC? And why don't we use it more often?

Answer

Both are IUPAC names, but used in different situations. For a 1 carbon aldehyde attached to a benzene, the one that must be used is benzaldehyde.

Aldehydes ($\ce{R-CHO}$) take the suffix "-al". If other functional groups are present, the chain is numbered such that the aldehyde carbon is in the "1" position, unless functional groups of higher precedence are present.

If a prefix form is required, "oxo-" is used (as for ketones), with the position number indicating the end of a chain: $\ce{CHOCH2COOH}$ is 3-oxopropanoic acid. If the carbon in the carbonyl group cannot be included in the attached chain (for instance in the case of cyclic aldehydes), the prefix "formyl-" or the suffix "-carbaldehyde" is used: $\ce{C6H11CHO}$ is cyclohexanecarbaldehyde. If an aldehyde is attached to a benzene and is the main functional group, the suffix becomes benzaldehyde.

For example, this guy would be cyclohex-2-ene-1-carbaldehyde:

christianity - star of david and the cross

I am a Christian and our church has a group of women that make prayer shawls for those who are sick or hurting or who are just plain in need of some comfort. We collect these shawls all month long then our group prays over them then on Sunday, they are dedicated and these shawls are given away free to any one in need no questions asked! We are going to make and send prayer shawls to those who lost loved ones and any one else who wants one in Newtown Ct.

My question is: one of the family's that lost a child is Jewish and we wanted to send a shawl that is white and has a cross in the pattern and hand sew a gold color crocheted star of David across from the cross but we are not sure if this is proper. Could you please advise?

organic chemistry - Ring expansion from a given cyclic carbocation

How will the cyclobutane ring behave in the case of cyclobutylmethylium (cyclobutylmethyl cation)?

I initially thought there would be ring expansion to a five membered ring so that there may be less angle strain and a secondary carbocation instead of a primary one. But I have also been told that there will be ring contraction for stability purposes. I would be highly obliged if someone could explain the mechanism involved here.

Answer

I think your friend is thinking of the cyclobutyl carbocation which does ring contract to the cycylopropyl carbinyl carbocation (and also equilibrates with the methallyl carbocation).

However, just as you thought, the cyclobutyl carbinyl carbocation does ring open to the cyclopentyl carbocation (ref_1, ref_2, ref_3). This rearrangement is driven by carbocation stability (primary to secondary) and relief of the steric strain present in the 4-membered ring, again, just as you suggested.

Note: this question has been asked previously on SE Chem, however I believe the accepted answer is incorrect, as it seems to primarily address the cyclopropyl carbinyl case, and what is said about the cyclobutyl carbinyl carbocation (little to no ring expansion) is incorrect.

The component 曷 and the kanjis 褐, 喝, 謁, 渇

Note the right component of the kanjis 褐, 喝, 謁 and 渇. It doesn't exist as a separate Chinese character, at least I couldn't find it. Those who have used Heisig will know that he refers to this component as 'siesta'.

It's not 曷, but it's close.

Now, when I look these kanjis up on Wiktionary, it gets complicated. Take 褐 for example. There are two forms of the kanji given, which look different on screen, one is 褐 and the other has 曷 as the right component, but when I copy and paste the latter, it looks exactly the same as 褐.

So I am confused now. Are there indeed two forms of these kanjis? How can the forms look different on screen but not when copied? And does the right component of 褐 exist as a separate Chinese character?

Answer

You're experiencing what happens on the internet due to han unification, and really bad handling of fonts if your browser language isn't set as one of Japanese, Chinese, or Korean.

These are all actually the exact same character, but browsers and webpages each change how it looks depending on if they think it's simplified Chinese, traditional Chinese, or shinjitai (jpn).

Under shinjitai, it's represented differently, despite being the same in traditional and simplified. Below is a comparison, using the respective "lang" attribute for each:

Note: The above comparison might not display correctly if you don't have fonts for the respective languages installed on your computer.

Because of Chinese, these different forms of the same character all have one codepoint, and are just seen as variant forms of one character (which they technically are). Because of that, though, unless a page tells a browser to represent it one way, or your browser consistently does so on its own (i.e. you set your language to one of chinese character forms, jpn, or kor), confusion arises.

---

Below are some images comparing the complete form of the character 喝, in the event you don't have the appropriate fonts installed:

• zho (simplified, traditional), kor, vie:



• jpn:

organic chemistry - Reaction of 1 equivalent of Mg in ether with 1,4-dibromobut-2-yne

What will be the product formed the if the reaction of Mg in ether with 1,4-dibromobut-2-yne occurs? At first, I thought the answer would be cyclobutyne, but the correct answer is buta-1,2,3-triene.

Can anyone please explain how?

Answer

Cyclobutyne cannot exist. There is no way to enforce 90° bends at both ends of a triple bond, but the carbanion formed by the Grignard reagent synthesis finds an easy way around this problem.

Let's say the magnesium reacts at position 1. Then the negative charge would couple with the conjugated triple bond to spread to position 3:

$\ce{Br\overset{+}{Mg}\overset{-}{C}H2-C#C-CH2Br <-> Br\overset{+}{Mg}CH2=C=\overset{-}{C}-CH2Br}$

Then the carbon atom at position 3 can act as a nucleophile, displacing the remaining bromine as a bromide ion to give the product named in the book.

word choice - 恥知らず【はじしらず】 versus 厚顔無恥【こうがんむち】

The lack of examples makes me difficult to understand well the difference between 恥知らず and 厚顔無恥. Both seem to mean "shameless".

For example, can I use both as follows? Are there any differences?

脱いだまま公園で散歩する人は恥知らずだ。
脱いだまま公園で散歩する人は厚顔無恥だ。

Answer

「恥知{はじし}らず」 is an originally Japanese word (大和言葉{やまとことば}) as you could tell from its reading/pronunciation. (Please do not be fooled by the use of kanji (恥 & 知). The kanji were just "assigned" to the word later on. Japanese was only a spoken language before we encountered the Chinese and started learning the kanji and created the kana.)

「厚顔無恥{こうがんむち}」 is, of course, a straight-up Sino-loanword.

Just like the million other Yamato-Sino word pairs, there is little to no difference in the basic meaning.

The difference that does exist is that the Sino counterpart tends to sound more formal, more academic, less intuitive, etc. than the Yamato counterpart.

Finally, the general differences between Yamato words and Sino loanwords are strikingly similar, IMHO, to those between English-origin words and "big" Latin loanwords used in English - begin vs. commence, worker vs. employee, put out vs. extinguish, go down vs. descend, etc.

organic chemistry - Solvents in substitution reactions

My book says that to favour a reaction by SN1 mechanism we need to use a polar protic solvent and a polar aprotic solvent in a reaction by SN2. * My Prior Knowledge:*

There are two types of polar sovents : Polar Protic Solvents contain a hydrogen bonded to a highly electronegative atom. They can solvate both positively and negatively charged species. On the other hand Polar Aprotic Solvents can only solvate positively charged species to an appreciable extent as there is no hydrogen bonding.

A question which arises now is that why should we use a Polar Aprotic Solvent in an SN2 reaction. The leaving group (which usually is negatively charged) needs to be stabilized as well. Wouldn't it be perfectly fine if I used a Polar Protic Solvent? If this is fine then why does presence of Polar Protic Solvent favor SN1 over SN2? Also I asked this question on SE a while back. I am looking for a more satisfactory answer apart from the ones given. here

Answer

Take the example of methyl bromide reacting with chloride ions:

In protic solvents the chloride ion is strongly solvated by hydrogen bonding and so the energy of the reactants is lowered, compared to in aprotic solvents. For the SN2 mechanism, the transition state is less polar than the reactants because the negative charge is spread out across the chlorine and the bromine and so the transition state is less stabilised by protic solvents than the reactants, increasing the activation energy of the reaction.

In aprotic solvents, the reactants and transition state are less stabilised because of the lack of hydrogen bonding but crucially the difference between the stabilisation of the reactants and the transition state is less and so the activation energy is lower, meaning that the SN2 reaction proceeds more quickly in aprotic solvents than in protic solvents.

The reverse argument applies to SN1 reactions where the first transition state is more polar than the reactants and so is more stabilised by protic solvents.

fourier - What is the unit of autocorrelation function?

In general, for autocorrelation of the deterministic signals,from the formula what is the unit of it.

grammar - how could a sentence end with (noun + "よ"?)

I'd thought you cannot end a sentence with a noun. Rather:
noun + だ。
noun + です。
noun + である。
noun + であります。

noun + でございます。

But in a movie dialogue, I heard: "大切なのは、心よ。"

Ending a sentence with a noun sounds weird. In every situation, I add "です" (or でございます). But, what is "よ"? a 助詞？Does it effect whether to voice the "です"?

Answer

I think it's the usual 終助詞「よ」 (sentence-final particle よ). What I've read is that it attaches directly to nouns in so-called 女性語 (feminine speech). I think it's often used in stereotyped dialogue in fiction, so it's also an example of 役割語 (role words)--though I don't mean to imply that it's only used in fiction, or only by women for that matter!

Wikipedia's article for 女性語 says:

よ 【終助詞】 「わ」と並んで多用される女性語。「ね」と同様、「そうよ」「きれいよ」など体言に直接続く形式は女性的とされる。ただし、「よ」を下降調で伸ばしながら発音すると、「あっしは神田の生まれよォ」のような男性的な表現になる。

I've bolded the relevant part for emphasis, which I'll translate loosely here:

In the same way that ね attaches directly to uninflected words, so can よ, as in the examples 「そうよ」 and 「きれいよ」. This use of よ is considered feminine.

The dictionary 大辞泉 also talks about this use of よ:

現代語では、終止形に付く場合、男性語としてはその終止形に直に下接するが、女性語では「のよ」「わよ」「ことよ」「てよ」などの形で、また、名詞、形容動詞の語幹に付いて、用いられることが多い。

Again, I've bolded the relevant part for emphasis, and I'll do my best to translate it:

In women's language, it is often used in forms such as 「のよ」「わよ」「ことよ」「てよ」, as well as attaching directly to nouns, including adjectival nouns.

Note: I changed the translation slightly at the end to say "adjectival noun" in place of 形容動詞の語幹, because the root of a 形容動詞 is simply called a na-adjective in the grammar that is usually taught to non-native speakers. The dictionary says it this way because, in traditional Japanese grammar, the combination of a na-adjective plus an inflectional ending such as だ or な is considered a single word.

---

At the end of your question, you ask if です is omitted before よ. I think you can analyze it that way, sure. Except I'd usually assume it's だ that's omitted, not です.

tefilla - Davening with a Minyan in China

I regularly travel to China (and other countries) for business purposes. I know there are other Jewish travelers who do the same which I sometimes meet on the way. I think that if we have the right system in place we could easily daven with a minyan. However, it is difficult to reach out to each person and make the right connections so everyone is at the same place, at the same time.

Is there anything that can be done to automate this process?

Answer

I don't know if there's such a system available at the moment but I came across a project on Kickstarter [ JPal ] that aims to automate this process.

According to the developers people can create a minyan "on demand" and have users who plan on being in the area notified of the new minyan. The app tracks participants in real time and displays all the relevant information to potential participants.

Here's a screenshot of the app:

I know that in the past there were some other websites that performed this functionality but they are no longer working at the moment.

inorganic chemistry - Why does Bismuth only create a +3 ion instead of a +5 ion?

It has 5 valence electrons, but only loses 3 of them to make a +3 ion. Why does this occur?

I believe it may have something to do with how losing 3 electrons leaves you with the p sublevel full, but I do not understand why Bismuth is okay with that.

Answer

Isn't it just that +5 is a lot of (positive) charge for a single cation? Which other (transition) metals do form a $\ce{M^{5+}}$ cation? Just out of my mind, I can't think of any.

Typically, these high oxidation states exist in the form of oxo-anions ($\ce{CrO4-}$, $\ce{MnO4-}$, $\ce{VO4^{3-}}$, etc.) and bismuth is no exception here: $\ce{Bi(V)}$ exists as bismutate ($\ce{BiO3-})$.

translation - Wanting Someone To Do Something (てほしい Structure)

I have the following sentence to translate.

行ってほしくないと言われたが
新聞記者になりたいので
国際交換瑠学生の試験に受からなくても行くことにした

So far I have the following.

It was said ... doesn't want ... to go but
he wants to become a newspaper reporter so
he decided to go even if he doesn't pass the international exchange student exam

I am having trouble with that first segment. I think the てほしい structure is used to say you want someone to do something for you. So I don't get who is not wanting who to go. If the subject just didn't want to go, I would expect 行きたくない.

Answer

You are correct in your understanding that ～てほしい is used when saying what you want others to do. 言われた is the passive, so the subject, literally, "was told 'I don't want you to go'". 行ってほしくない is what they were told by someone else.

The main point of this passage is that the subject intends to go despite being told by someone that they don't want them to go.

As as sidenote regarding translation, it might just be me being sleepy here but I don't think a literal translation of the grammar results in very natural English. Some solutions might be to get rid of the passive ("They told me they don't want me to go but...") or change the "want" ("I was told not to go/...I shouldn't go but...").

organic chemistry - Is the compound CH2(OH)(ONa) possible?

I was just pondering about the reaction mechanism of Cannizzaro reaction.

$\ce{H2C^{+}-O- + OH- -> H2C(OH)O-}$

$\ce{HCHO + H2C(OH)O- -> H3CO- + HCOOH}$

$\ce{H3CO- + HCOOH -> HCOO- + H3COH}$

I wondered why in 2nd step instead of receiving $\ce{H-}$ from $\ce{H2C(OH)O-}$; $\ce{H2C^{+}-O-}$ wouldn't react with NaOH to form $\ce{H2C(OH)ONa}$.

I don't think this compound will be able to exist. But don't know why! Everything seems right about it.

Answer

Of course, you shouldn’t start from $\ce{H2C+-O-}$ unless you note that it is a mesomeric form of $\ce{H2C=O}$ — the more relevant mesmeric structure.

The mechanism as you wrote it and as it is typically written is given without any counterion, i.e. using just $\ce{OH-}$ and not $\ce{NaOH}$. You could instead write the mechanism using a counterion for $\ce{OH-}$ — $\ce{Na+}$, which would result in the first step being:

$$\ce{H2C=O + NaOH -> H2C(ONa)(OH)}\tag{1}$$

This is essentially the compound you are suggesting. Hence it exists, but it is a minor constituent of the overall solution. It’s not part of the second step, it is the first step. For the second step to happen, you need another molecule of $\ce{H2C=O}$, which has not yet reacted to the geminal diolate $\ce{H2C(ONa)(OH)}$.

See this scheme for the transition state of the Cannizzaro reaction and where $\ce{H2C(ONa)(OH)}$ comes into play:

How to calculate the impulse response of an RC circuit using time-domain method

I have an $RC$ circuit and I calculate the differential equation as
$$RC \frac{dV_c}{ dt} + V_c = V_g$$ that is the same of
$$RCy'(t) + y(t) = x'(t).$$ If I assume $x(t) = u(t)$ I have that the equation is $$RCg’(t) + g(t) = 0$$ and the solution is $$g(t) = K_1 e^{-t/RC} + K_0$$ now for have the impulse response I have to calculate this for $t > 0$, $t < 0$ and $ t= 0$ but I have no idea how to do. Can you please help me ?

grammar - Do the adverbial forms of verbs and nouns exist?

I know there are adverbial forms of:

• adjectives (Adj), 形容詞{けいようし} (連用形{れんようけい} - 早い→早く);


• adjectival nouns (AdjN), 形容動詞{けいようどうし} (連用形{れんようけい} - 上手だ→上手に).

Are there adverbial forms of nouns (名詞{めいし}) and verbs (動詞{どうし})? If they do exist (regardless of semantics), is there a generic rule like Adjs's and AdjNs's or not? How can they be constructed?

Answer

Verbs

I don't think that the て-form and the continuative form verbs qualify as an "adverbial" form, but at least they add meaning to the following verb just like adverbs.

Compare these:

流れている (流れる, an ichidan verb, in the て-form)

ご飯を食べて寝る* (食べる, an ichidan verb, in the て-form)

*everything preceding the て-form verb is included in the "adverbial" clause

ゆっくり話す (just an adverb for comparison)

決して忘れない (This is an interesting one. It is an actual adverb, but clearly based on the verb 決する.)

抱きしめる* (抱く, a godan verb, in the continuative form)

*maybe it is the other way around here, しめる adding meaning to 抱く

早く寝る (早い, an i-adjective from your example)

It should be noted that these verb forms have many other uses in addition to modifying following verbs. For example, the continuative form is used create the て-form:

ichidan: 流れ(cont.)+て

godan: 抱い(alternative cont.)+て)

It attaches to a noun to create another kind of meaning:

やり(cont.)+方

The て-form can also be used in various ways that don't resemble adverbs in my opinion.

Nouns

As Igor Skochinsky pointed out in comments, you can actually add -的 to nouns to make them adjectival nouns and as you said in the question, it will become an adverb when you add -に. The resulting adverbs aren't guaranteed to make sense, but that wasn't a requirement. Other ways to use nouns as adverbs depend on the noun in question. Some examples below:

• 
  

  Temporal nouns like 今年 can be both adverbs and nouns without adding anything, and nouns like 後 can be turned into adverbs by adding に or で in addition to being an adverb on their own in some situations.

  
  
  


• 
  

  Any noun that works as a verb with する can be used with the て-form (して) like ichidan and godan verbs in the examples. Like the examples, this isn't an adverb but something resembling it.

  
  

segulah - sources that neatness brings brocho/mazal

I heard in a daf yomi shiur on the end of Moed Katan (27a ‘Couch of Fortune’) that Jews kept an extra neat bed for brocho/mazal.
One of the reasons that he gave was that in general neatness brings brocho/mazal (malach of brocho/mazal).

Were can I find sources for this?

And it seems that even now Jews have a custom to keep a neat home.

everyday chemistry - How pure NaCl is typical table salt? How is it purified?

How pure $\ce{NaCl}$ is typical table salt? Is it pure enough for research-level experiments in chemistry? How is $\ce{NaCl}$ purified if need to be?

Answer

Table salt is often iodized (iodine is an essential micronutrient, and this is one way to introduce it into the diet in the right amount). According to Wikipedia,

Edible salt can be iodised by spraying it with a potassium iodate or potassium iodide solution. 60 ml of potassium iodate, costing about US $1.15 (in 2006), is required to iodise a ton of salt. Dextrose is added as a stabilizer to prevent potassium iodide from oxidizing and evaporating. Anti-caking agents such as calcium silicate are commonly added to table salt to prevent clumping.

Elsewhere, Wikipedia mentions other anti-caking agents, like sodium ferrocyanide, sodium aluminosilicate, and magnesium carbonate. And they point out that salt may also be "fortified" with iron or other micronutrients.

The certificate of analysis for "ultra pure NaCl" from American Bio shows TRACE amounts of aluminum, arsenic, bromides, heavy metals, iron, magnesium, phosphates, and sulfates. Those impurities may well be expected in table salt, too.

From all that, you'd think that table salt is fairly impure. Let's look at the numbers to put the amounts of these impurities in perspective. The box of Morton iodized salt in my kitchen gives me the amount of sodium per serving. If all of the sodium is in the sodium chloride, I estimate the purity as

$$\frac{0.590~\mathrm{g}~\ce{Na+}}{1.5~\mathrm{g}~\text{table salt}}\frac{1~\mathrm{mol}~ \ce{Na+}}{22.989769280~\mathrm{g}~\ce{Na+}} \frac{1~\mathrm{mol}~\ce{NaCl}}{1~\mathrm{mol}~\ce{Na+}}\frac{58.44277~\mathrm{g}~\ce{NaCl}}{1~\mathrm{mol}~\ce{NaCl}}\cdot 100\% = \fbox{99.99% NaCl}$$

where I'm assuming the label information is actually a bit more precise than reported (exactly 1.5 g of table salt contains approximately 590 mg Na). This is just a BOE (Back of the Envelope) calculation; I should round my answer to three or possibly two significant figures.

In fact there are sometimes other sodium salts present (anti-caking estimates such as Tivolex contain sodium) so this purity is a slight overestimate. One salt company (WA Salt supply) lists "typical" purities for the table salt it provides at 99.72%; this salt contains uses Tivolex. Morton Salt claims that their iodized table salt contains 0.04% dextrose and "less than 0.5% calcium silicate", so the mg Na per serving on the label is a little bit higher than it actually is; I should get something above 99.46%, considering that additional information.

Still, that's pretty pure. The assay for "ultra pure" NaCl linked above gives 99% to 100.5% NaCl. Sigma-Aldrich has reagent-grade NaCl (>98%), ACS grade NaCl (>99.5%) and TraceSelect NaCl for doing heavy metal analysis that is more than 99.999% pure.

Is 99% purity "pure enough for high level experiments in chemistry?" There is no one answer. It depends on what those experiments are. How many significant digits do you need in your results? Are the results going to be affected by the presence of tiny amounts of iodide, iodate, glucose, calcium, or silicate, or the other impurities listed above? Maybe, maybe not. If a specific impurity interferes, find a way to lock up, remove or otherwise neutralize its effects.

audio - Why are MFCCs of two equivalent signals completely different?

I have an audio file, of which I calculate 16 (actually 15 because I omit the first one) MFCCs in R. When I stream this file via VLC-Player and Icecast2-Server, receive it in Java (with the Player of Javazoom-Lib) and then pass it on to R again for MFCC calculation I get completely different values? Has anyone an idea why this could be?

Additional info:

• When I write the received data to a file again and view it next to the original file they look almost the same (Waveform + Spectrogram).


• The file has a length of 3 seconds and contains the sound of a passing vehicle (car).


• MFCCs are calculated for centered 44100 samples.


• I need valid data in order to automatically classify cars and trucks with a SVM. This classifier is trained with features calculated from 150 audio files (each containing one vehicle).


• Since R had problems with reading and processing mp3-files directly I first converted wav to mp3 and back again (in order to "simulate" the loss of information due to compression).

Furthermore, I automatically detect the vehicles in a continuous audio stream and therefore (for the particular example data above) the waveforms for calculating the MFCCs have an offset of about 4400 Samples. Does this matter with an analysis window of 44100 samples?

Answer

You say:

I stream this file via VLC-Player and Icecast2-Server, receive it in Java (with the Player of Javazoom-Lib)

When you receive the stream in Java, what is the stream format?

You say that it is the "same" because the waveform and/or spectrogram look similar, but the MFCCs will come out different if the stream format (sample rate, bit depth, etc) are different.

Can you confirm by printing out the stream formats

1. Before sending to Java


2. Upon receiving from Java?

I recommend using Soxi to print out the stream format (if you cannot otherwise dump it from R, or Java)

If you can eliminate stream format issues, mp3<->wav issues (deal only in wav), if you analysis windows are identical (as jojek says), then your MFCCs should come out identical.

inorganic chemistry - Methanol adducts with CaCl2

Methanol forms adducts with $\ce{CaCl2}$ but I am not finding much information about the nature of these adducts & their stability. Are these solid adducts? Crystalline? Is the reaction substantially exothermic etc.?

In this link, it is written that:-

At temperatures below 55°C, $\ce{CaCl2}$ forms $\ce{CaCl2·4CH3OH}$ with methanol and below 55°C, $\ce{CaCl2·3CH3OH}$ is formed.

Obviously, they seem to have gotten their Temperatures wrong. Any more authoritative information about methanol adducts?

translation - Is there a rule for Rashi's French transliterations (Laaz)?

Rashi frequently uses French words in his explanation to Chumash or the Gemara. However, he doesn't write it in the original language, but he writes it in a "transliteration" of French in Hebrew lettering.

Are there any rules to "transliterate" it back to French?

Answer

If I'm not mistaken, Dayan Gukovitzky's Targum HaLaaz has a transliteration guide. It seems that Rashi did have a specific set of rules for doing this.

sources mekorot - Responsum of Maimonides Regarding Translating Mishne Torah

The Maimonides Reader (p. 478) quotes Rambam's responsum to Ibn Gabir regarding translating the MT (also referenced here). He responds to a request from this Arabic speaker who was able to learn Peirush Hamishnayos, but unable to learn MT. Rambam responds that he wont be translating the MT into Arabic, and in fact is translating his Arabic works into Hebrew, but encourages the questioner to pursue his studies.

Does anyone know where else this responsum can be found? (Preferably in the 1859 Kovetz Tshuvos Harambam, the Blau tshuvos, or the P'er Hador tshuvos).

Answer

The Rambam's responsum to Yoseph ben Gabir you're looking for begins on the 177th page of Qovetz Teshuvot ha-Rambam ve-Igrotav (Leipzig 1859). It's also available on Sefaria.

Which Animals Have Only One Kosher Sign?

Vayikra 11:4-7 mentions four animals that either chew their cud or have split hooves, but do not posses both kosher signs and are therefore not kosher. At the present time, is this a complete list or only partial? If it is only partial, where can I find a complete list?

torah reading - Shalsheles Trop

How often is the Shalseles Trop found in the Torah, and where?

Answer

Four times in Chumash:

ויתמהמה (Vayeira, Gen. 19:16)

ויאמר (Chayei Sarah, Gen. 24:12)

וימאן (Vayeishev, Gen. 39:8)

וישחט (Tzav, Lev. 8:23)

and three times in the rest of Tanach (excluding Tehillim, Mishlei, and Iyov, which use a different system of trop):

ונבהלו (Is. 13:8)

ויאמר (Amos 1:2)

ואמר-לה (Ezra 5:15)

kanji - Japanese for "Dami Im"

How would I translate Dami Im's name into Japanese?

Im was born in South Korea (her name in Korean is 임다미), but moved to Australia when she was nine. "Dami" is her given name, and "Im" is her surname, based on her father's name being Dong Eal Im.

Is it ok to just use "ダミ･イム", like the Japanese edition of Wikipedia does? Or ought I try to work out the kanji equivalent of "Dami" and "Im", like how Ban Ki-moon is 潘基文 according to the Japanese edition of Wikipedia?

Does the fact that she's a singer (or any kind of celebrity) mean that she's more likely to have a katakana name than someone who isn't a celebrity (such as a politician or a scientist)?

I've also seen her name reversed back to surname first (イム･ダミ) here.

Answer

The three characters read 임(Im)다(Da)미(Mi). This is her Korean name.

I feel ダミ･イム and イム･ダミ are both fine. But, I prefer ダミ･イム. Basically, we try to copy native pronunciation of that person. For example, Michael has several ways of reading in Hebrew, English, German, French, etc. So, it is written in various forms like ミカエル, マイケル, ミハエル, ミチェル, etc. It seems that Dami Im is mainly based in Australia, and she is now an Australian. So, I want to import her name from English.

Probably, Im is 任 or 林, but basically there is no way to know what Kanjis are appropriate unless you ask her parents or herself. Now Koreans do not use Kanji in their daily life although most Koreans have their Kanji name. If you go to her wedding, probably you will see her Kanji name.

You can find several Kanji examples of 임다미 in the link below. 林多彌, 林爹彌, 林茶彌, 任茶迷, 林爹媺. http://www.erumy.com/nameAnalyze/AnalyzeMyName.aspx?name=%EC%9E%84%EB%8B%A4%EB%AF%B8

In old days, Japanese tend to write Chinese and Korean name in Kanji, and read it in Japanese way. For example, Kim Dae-jung (金大中), a president of South Korea, was called きんだいちゅう (Kin DaiTyuu).

However, there was a movement to read Korean names in a native way (現地読み) in 1984. Korean government had asked Japanese government and media to do so. And, Japanese government accepted this just before a president, Chun Doo-hwan (全斗煥, チョン・ドファン (Korean reading) or ぜんとかん(Japanese reading)) came to Japan. Japanese media also followed. As a result, we tend to read 金大中 as きむでじゅん (Kimu DeJun). Still, the old way of reading is OK.

On the other hand, Chinese government reads Japanese name in Chinese way, and they have not asked this. So, nothing has changed for Chinese names. (For example, Hu Jintao, 胡錦濤 is こきんとう Ko KinTou. Yet, フーチンタオ is OK, but it is hard to understand this.)

The reason why we tend to write a Korean politician or scientist's name in Kanji is probably that s/he is so old and famous that we know their Kanji name. It is shorter and easier to understand. But, as for young singers, we do not know their Kanji name anyway.