etymology - Why aren't マンション mansions? Or are they?

And no, this isn't about property sizes in Japan!

As Katakana Mysteries: 6 loan words Japan got wrong put it:

Bill Gates or Warren Buffet might be very surprised if they were to buy a Japanese manshon, only to find upon their arrival something a bit less grand than they envisioned, and that they would be sharing it with quite a few other people.

The English edition of Wiktionary claims that it is derived from English:

Etymology

From English mansion.

Note that while English “mansion” most commonly means “large house”, it is also occasionally used to mean “luxurious apartment”, the latter usage being followed in Japanese.

And the English language Wiktionary article talks about mansion meaning "A luxurious flat" being UK English, which I've heard was the main source of English in the 19th century.

Japanese English - 10 Truly Bizarre Examples Of Wasei-Eigo claims it might be borrowed from French:

マンション (mansion)

Don't get too excited if you're moving to Japan to live in a mansion. These mansions are actually condominiums. I have no idea how this creation came about. Some of the mansions I've seen in Japan were less than luxurious. Is it a joke? I suspect it might be a borrowed word from French.

Is 「マンション」 derived from English, or French? And did Japanese mess up the meaning of "mansion", or were they being faithful to a meaning that is rarely used nowadays?

Answer

I have nothing to back this up, but following on from Zhen Lin's comment:

It may have come from the British English "mansion block", which I think was a Victorian invention - the typical one would be something rather impressive in red brick within a suitably posh London postcode.

They often have names of the form "XYZ Mansions", for example Albert Hall Mansions and the individual apartments within are called "mansion flats". The term is still in use (but tends to refer to a period building rather than a new build).

This site says the term in Japanese really started up in the 1960s - so then again it might just have been the adoption of a word that made the apartments in question sound more luxurious - the same reason for the establishment of the phrase 'mansion block' in English in the first place.

reward punishment - equivalent schar

so nothing in this world is comparable. but for the sake of this question, comparison is needed. compare a girl, named Chanie brought up in Monroe, and a girl named Clara brought up in Las vegas, in an extremely progressive neighborhood, where modern orthodox is viewed as fanatic. now lets analyze this chanie and clara. their line of bechira lie in two very diverse places. chanie is faced with challenges such as, having a hard time davening mariv, while clara is struggling with shabbos. however they are both as good or if not better than their upbringing. now, hashem was the one to situate Chanie and Clara in their designated communities. question. wasup with their schar? is it equivalent? their life styles are so nonidentical, but will their oilem haba be corresponding?

halacha - Tallit Katan and Tallit brachot

Why is that when you wake up you put on a Tallit Katan and then you go to shul and put on a Tallit Gadol? How is it that you can say two different brachot? If it is in fact, that each peice of clothing gets the the chance for a new bracha, are there any other mitzvot, aside from food, where we recite a bracha each and every time we do the SAME action? Of those allowed are there any we commonly do multiple time as we do with the Tallit?

Answer

The custom among (as far as I know all) Ashk'nazim (and maybe among others also?) is that someone who dons a talis katan in the morning intending to don a talis gadol later (for prayers) does not say a b'racha on the former. However, I have no citation for this: I'm not seeing it in the Mishna B'rura, and certain parts of Shulchan Aruch Orach Chayim 8 seem to directly contradict it (cf. Double AA's answer).

Update: As Shalom mentions in a comment on this answer, MB 8:24 cites with approval the practice I am familiar with.

Earliest Sources To Avoid Pronouncing the Name 'Samael'

What are the earliest explicit sources that reference the practice of not pronouncing the name 'Samael'?

I ask since I have heard many people doing this. It is referenced here: http://www.yeshiva.org.il/ask/?q=%D7%A1%D7%9E%D7%90%D7%9C&search_in=0

Answer

Rav Shmuel Vital (17th century) in the siddur חמדת ישראל says this.

גם צריך להזהר מאד שלא להזכיר בפיו שם סמא"ל וזהו סוד מש"ה אלהים אחרים לא תזכירו וכו' ובפרט בלילה שאז היא שליטתו וממשלתו.ולא עוד אלא שגם הוא אסור להזכיר מעין דברים אלו כגון בני אדם הרגילים לומר בלשון לע"ז איל דייאבל"ו וכיוצא בדברים אלו אין להזכירם כלל לפי שגם השדי"ם הם בחלקו ומגביר כוחו כשיזכיר אותם. ופעם אחת הייתי עם בני אדם בלילה והזכרתי באמצע הדיבור שהייתי עמהם את שם סמא"ל ואח"כ בבקר הלכתי לבית מורי ז"ל ונסתכל בי ואמר לי הרי בלילה הזאת עברת על לאו ושם אלהים אחרים לא תזכירו. ולכן הזהר כל ימיך שלא תזכירו לא את שמו ולא כיוצא בו ובפרט בלילה כי אז ניתן לו כח להתגבר עליך ועל אחרים בסיבתך אם תזכי שמו ולכן ראוי להזכירו בשם אחד טוב כמו סמ"ך מ"ם וכיוצא מאלו השמות שיש בהם מקצת קדושה כל זה לשון אזהרת מורי זלה"ה

I don't know if this is the earliest source, but it seems like it would be.

Flipping the impulse response in convolution

During convolution on a signal, why do we need to flip the impulse response during the process?

Answer

Adapted from an answer to a different question (as mentioned in a comment) in the hope that this question will not get thrown up repeatedly by Community Wiki as one of the Top Questions....

There is no "flipping" of the impulse response by a linear (time-invariant) system. The output of a linear time-invariant system is the sum of scaled and time-delayed versions of the impulse response, not the "flipped" impulse response.

We break down the input signal $x$ into a sum of scaled unit pulse signals. The system response to the unit pulse signal $\cdots, ~0, ~0, ~1, ~0, ~0, \cdots$ is the impulse response or pulse response $$h[0], ~h[1], \cdots, ~h[n], \cdots$$ and so by the scaling property the single input value $x[0]$, or, if you prefer $$x[0](\cdots, ~0, ~0, ~1, ~0,~ 0, \cdots) = \cdots ~0, ~0, ~x[0], ~0, ~0, \cdots$$ creates a response $$x[0]h[0], ~~x[0]h[1], \cdots, ~~x[0]h[n], \cdots$$

Similarly, the single input value $x[1]$ or creates $$x[1](\cdots, ~0, ~0, ~0, ~1,~ 0, \cdots) = \cdots ~0, ~0, ~0, ~x[1], ~0, \cdots$$ creates a response $$0, x[1]h[0], ~~x[1]h[1], \cdots, ~~x[1]h[n-1], x[1]h[n] \cdots$$ Notice the delay in the response to $x[1]$. We can continue further in this vein, but it is best to switch to a more tabular form and show the various outputs aligned properly in time. We have $$\begin{array}{l|l|l|l|l|l|l|l} \text{time} \to & 0 &1 &2 & \cdots & n & n+1 & \cdots \\ \hline x[0] & x[0]h[0] &x[0]h[1] &x[0]h[2] & \cdots &x[0]h[n] & x[0]h[n+1] & \cdots\\ \hline x[1] & 0 & x[1]h[0] &x[1]h[1] & \cdots &x[1]h[n-1] & x[1]h[n] & \cdots\\ \hline x[2] & 0 & 0 &x[2]h[0] & \cdots &x[2]h[n-2] & x[2]h[n-1] & \cdots\\ \hline \vdots & \vdots & \vdots & \vdots & \ddots & \\ \hline x[m] & 0 &0 & 0 & \cdots & x[m]h[n-m] & x[m]h[n-m+1] & \cdots \\ \hline \vdots & \vdots & \vdots & \vdots & \ddots \end{array}$$ The rows in the above array are precisely the scaled and delayed versions of the impulse response that add up to the response $y$ to input signal $x$. But if you ask a more specific question such as

What is the output at time $n$?

then you can get the answer by summing the $n$-th column to get $$\begin{align*} y[n] &= x[0]h[n] + x[1]h[n-1] + x[2]h[n-2] + \cdots + x[m]h[n-m] + \cdots\\ &= \sum_{m=0}^{\infty} x[m]h[n-m], \end{align*}$$ the beloved convolution formula that befuddles generations of students because the impulse response seems to be "flipped over" or running backwards in time. But, what people seem to forget is that instead we could have written $$\begin{align*} y[n] &= x[n]h[0] + x[n-1]h[1] + x[n-2]h[2] + \cdots + x[0]h[n] + \cdots\\ &= \sum_{m=0}^{\infty} x[n-m]h[m], \end{align*}$$ so that it is the input that seems "flipped over" or running backwards in time! In other words, it is human beings who flip the impulse response (or the input) over when computing the response at time $n$ using the convolution formula, but the system itself does nothing of the sort.

home experiment - Is this reaction to produce ammonium sulfide safe?

For my chemistry experiment, I was assigned to produce ammonium sulfide and test the chemical properties of the compound. From my online research, I found out that I can mix household ammonia and match heads to produce Ammonia Sulfide.

I think this will satisfy the purpose of my assignment, but I have a few concerns.

I'm not sure what proportions I should mix these materials in order to produce an ideal solution. I am also unsure about the exact results of mixing ammonia and match heads, since match heads consists of more than just sulfer, but also potassium chlorate, antimony trisulfide, and some oxidizing agents. Will the end product potentially be dangerous? I plan to mix the two chemicals in a enclosed test tube, and seal it for a few days.

minhag - פ in German Sta"M Script

Does anyone know the German custom for the letter pey in Sta"m sofer? I know that the shape in Litvisch Bet Yosef is influenced by the Mekubalim of Tzfat (The Ari in particular) who said that the letter bet should appear within the pey. As the Germans were quite averse to most anything kabbalistic, would this apply to a sefer written by someone who follows German minhagim?

Answer

This is the picture from my sefer, which experts have identified as either German or Czech. As you can see, there is a beis visible inside the Peh but it made neither in the style of the old European Bet Yosef ksav nor the Mishna Berurah's modification.