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Posted by8 years ago
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## Dear r/math: last week my C language prof asked how many of us in the classroom (60 give or take) were math majors. Only I raised my hand and virtually everybody else laughed, snorted or giggled.

Furthermore, out of around 17k alumni college-wide, there are no more than 20 math undergraduate majors at any given time, at any point of our careers. Besides, a lot of engineering majors don't actually see the usefulness of the math or chemistry courses (most of them keep shut about the physics courses but don't enjoy them anyway), and don't even get me started on the humanities majors.

So, is this insignificant ratio of math majors common in other universities? Is the lack of respect for hard science/math courses common? And most importantly, I really think I should do something about this math-majors-are-losers point of view, any suggestions?

EDIT: there's the possibility that they were just laughing about the ratio of non math to math majors and not about majoring in math by itself. I don't want to give the impression that my university is full of fools (I certainly don't think that) but I am sure that there are a ton of students that don't take seriously enough the courses they (are forced to) take and are quite ignorant about some of the most fundamental topics in academic life. I think that's what really bugs me: that, say, the engineer that is probably going to build my future condo doesn't have a clear concept of the foundations of science and engineering.

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22 points · 8 years ago

I'm an engineering major, and I would never laugh at a math major. In my opinion, any university in which people laugh at math majors is a university full of fools.

Original Poster1 point · 8 years ago

Sadly, this is regarded as one of the best universities in the country.

2 points · 8 years ago

What university?

Original Poster3 points · 8 years ago · edited 8 years ago

Pm'ed you.

EDIT: don't get me wrong, it IS a good university and there are a lot of valuable teachers and students around... they are just not the majority. EDIT2: edited for privacy...

2 points · 8 years ago

Aaah, this makes a lot more sense now.

I'm not sure exactly what the history of this is, but Peru is one of the countries where maths isn't seen as a vocational subject in any way. It's the same as Spain.

Basically, whereas in other countries (e.g. England) you can get a maths degree and have plentiful job opportunities, people only tend to do maths in Peru/Spain if they want to go into academia. (Or at least, this is how the majority see it, I am told)

I wouldn't worry too much about it. Also, fucking props that you're studying in Lima! I love Peru so much; was hoping I could sneakily study abroad there for a year somehow, but England-Peru links are few and far between.

Original Poster2 points · 8 years ago

The history is simple (as sheep1e pointed out): high school math courses are focused on teaching the computation of answers, not in teaching to think in a mathematical way, the mere concept or usefulness of mathematical objects and creativity, much less on mathematical beauty.

35 points · 8 years ago

I want you to seriously consider the possibility that, while the other students were laughing, they weren't laughing at you or at maths. They just found it funny that only one of you was a math major. Try not to get too paranoid about the other students.

Original Poster5 points · 8 years ago

Yes, I shouldn't have been so quick by judging all of them.

However, there IS this general despite for math courses I talked about. Also, the usual response when I tell someone I'm a math major is: "Really? Pure math? So you want to spend all your life teaching at college?' or the occasional 'So you'll waste your time creating new formulas?' and the most disappointing of all (from a chem prof): 'So you'll call me when you get the Nobel prize for Mathematics'.......

It's just sad to realize how ignorant people, at least marginally involved in academia, are about such a fundamental topic.

[deleted]
2 points · 8 years ago

However, there IS this general despite for math courses I talked about.

Definitely. I myself am a CS major and I hated the math courses really. It's just that in the first two years, you are forced to learn stuff you don't ever use throughout your whole Bachelor. What I always find weird is that Physics majors have to do less math than us CS guys.

2 points · 8 years ago

Wait, what? At my school the Physics majors do more (applied) math than the Math majors or any other field for that matter.

1 point · 8 years ago

I was an undergrad physics major, and after all the math classes, I was about 12 credits short of a second major in math.

2 points · 8 years ago

If you branch out in CS, many of the subfields will require you to be pretty intimate with math. For machine learning, if I wasn't already very comfortable with linear algebra and multidimensional calculus (note: I also studied math), I would have had a very hard time passing that course. This applies even more for CS theory or numerical analysis. Unless you take only easy and boring CS courses, you will need math eventually.

Original Poster1 point · 8 years ago · edited 8 years ago

Perhaps you should see it in a different way. I firmly believe that mathematical training can be useful, if not for the contents of it (which are quickly forgotten if you don't use them), but for the ways of thinking and solving problems. I don't know of any other discipline similar to math in this respect.

For example, in the reddit interview with Peter Norvig, he was asked how he tackled difficult problems (or something similar). He cited Polya's book 'How to solve it', a classic in mathematics studies and teaching.

[deleted]
2 points · 8 years ago

I am a final year undergrad with majors in analytical economics, computer science and applied mathematics and pure mathematics. Imagine what it's like for me in economics classes, very few of them bother to take any university level maths units, let alone the later year pure math units.

I'm intending to do honours in mathematics next year before going on to do more eco (game theory most probably, and whatever I can find time for with micro).

It's alright though, you will leave them in the dust in a few years.

Original Poster1 point · 8 years ago

It's the same here. At my university (as explained in another post), we get separated from the start so that all science/engineering majors and humanities/social sciences majors take their courses together (at least some 80% of them). Of course, economics gets stuffed with the humanities and other social sciences and I can't begin to understand how an economics major can hate taking math courses or even not see the usefulness in them.

Admittedly, this is all in the undergraduate students. There are a couple of masters programs in mathematical economics and applied math and all the math related postgraduate programs sum up some 40 students. These programs are rapidly getting bigger, mainly because of some really valuable professors and are being used as a compensation for a poor mathematical training in undergraduate studies before getting out of the country to get another degree.

1 point · 8 years ago

Your math, cs and applied math will serve you well - just stay away from econ - it's a field full of charlatans.

[deleted]
5 points · 8 years ago

I agree that there are too many idiot's who claim to be economists, but the field of study in itself is not uninteresting or unworthy. If I do vary from pure mathematics it's intended to be the highly theoretical side of game theory and microeconomics.

2 points · 8 years ago

I wouldn't worry too much about other students. As a Biology major, I would kill to be in your position (with a good understanding of math).

I'm dabbling in bioinformatics programming and I'm quickly realizing how important math is for data mining, gene prediction, protein prediction, etc...

Math is the universal language, ignore those who say you'll be stuck teaching at college. With a solid understanding of math, the world is your oyster.

Original Poster2 points · 8 years ago

I've been doing this ever since I started to like math (some 6 years ago) but the whole rant was about getting really tired of being surrounded by such ignorance.

What the hell, I suppose I'm better off ignoring them, it's just that it's so disappointing.

2 points · 8 years ago

I understand that it's frustrating to be surrounded by ignorance but it would be a wasted effort to correct this ignorance. These people are ignorant by their own choosing.

It's best to let it be and direct your energy into things that are actually worthwhile (like more math!). Life is too short to be concerned with others ignorant opinions/viewpoints.

Original Poster2 points · 8 years ago

You made your point, sir. I think I'm just fed up with the mediocre lifestyle most people live here. We really need some changes and one would think that colleges are the best place to start looking for great minds. There ARE a lot of valuable people, just fewer than I thought and WAY TOO MUCH fewer than this country needs.

1 point · 8 years ago

Chin up friend. The best way to inspire young minds (including your peers) to greatness is to lead by example. From your comments I think this is something you are already doing.

12 points · 8 years ago

Being good at math gets you women. Don't tell everybody or you will ruin it for the rest us.

[deleted]
9 points · 8 years ago
Comment deleted8 years ago
Original Poster3 points · 8 years ago

Damn right you are!

10 points · 8 years ago

My motivation for going to university to study mathematics was intellectual curiosity.

At school we had learned the formula for solving quadratic equations and I knew the was a terribly complicated formula for solving cubic equations. Not only that, but there was an even worse formula for solving quartic equations. It seemed unsurprising that attempts to find a formula for the general quintic had failed, but there was a problem. Mathematicians claimed to have a proof that there was no such formula.

If the claim had been that quadratic were solvable but cubics had been proved to be insoluble, one would not be so amazed. One could imagine a proof along the following lines: first one shows that any solution must be fairly simple, second one conducts an exhaustive search of the simple possibilities.

However, the formula for the cubic and the quartic hinted of inexhaustible possibilities. Indeed the trajectory, quadratic, cubic, quartic, quintic, seemed to be towards ramifying intractability, which, if it posed problems for those searching for a formula for the quinitic, would seem to pose even more formidible problems for those trying to prove that such a formula did not exist. How could such a proof be possible? I wanted to go to University and study it for myself.

There were other mysteries. Conservation of energy quite naturally limits the energy one might hope for from a heat engine to be no more than the energy available in the fuel. However, unless the fuel burned hot, the limits were in fact much stricter. There was a second law of thermodynamics, originating in an understanding of heat as randomness. How did that work?

FM radio gave better reception than AM radio because it used a different method for modulating the carrier. Could ever more ingenious modulation schemes improve radio without limit. Shannon had a theory of information that not only answered this question but, mind-bogglingly did so in a way that seemed connected to the 2nd law of thermodynamics. I wanted to learn about that.

It seemed obvious to me that any mathmatical theorem was either true and provable or false and disprovable. I was not ashamed of this intuition. It was what the great mathematicians of the 19th century had believed. Nevertheless Godel had shown that statements could be true but not provable. Stranger still he had shown that the problem was not fixable. Any system capable of proving ordinary statements about addition and multiplication had this problem.

I knew that computer programs often had flaws and people tried to write computer programs that analysed other computer programs to find their flaws. There was some kind of problem. A serious problem. It was known that one could not even write a fully general program to check that programs would halt. This struck me as in the domain of the grungily practical, as computer time was expensive, and run-away programs ran up large bills. Yet somehow this was related to the abstruse meta-mathematics of Kurt Godel. What on earth was going on?

And so on, with Maxwell's equations, their insane transformation group, and the mystery of simultaneity. How dare the basis of electrical machines, the big pieces of copper and iron that kept the lights on, be so bizarre. And quantum mechanics and curved space-time and nuclear physics...

Such fascinating strangeness and mathematics the only key. How could any-one with a soul resist the lure of these mysteries, simultaneously esoteric and exoteric?

And most importantly, I really think I should do something about this math-majors-are-losers point of view, any suggestions?

Do nothing. You are not the one with the problem.

Original Poster2 points · 8 years ago · edited 8 years ago

You, sir, have put forward the motivation quite beautifully. The deep interconnectedness of science and mathematics (of the real world and our imagination) is a question that (I think) humbles any and all mathematicians and scientists alike. I could not upvote you enough.

You are not the one with the problem.

The thing is that I don't feel quite part of the solution either.

11 points · 8 years ago

Those who are unable to see the utility as well as the importance of pure mathematical education are only advertising their own stupidity and ignorance.

Ignore such individuals... they are trivial.

Original Poster2 points · 8 years ago

That's why I feel obliged to do something about it, I can't stand to study in a college where most people are trivial.

Side note: I would say stupidity or ignorance.

2 points · 8 years ago

Ignorance is a big part of it - high schools generally do a terrible job of communicating to students what math really is. As a result, people end up with ridiculous misconceptions about what math is - and their reactions to hearing about someone majoring in math reflect that. Try asking people to describe what they think math is about, it can be amusing.

Original Poster1 point · 8 years ago

Amusing and depressing as hell. I'm absolutely sure that high schools are to blame here, specially public schools (I'm in Perú btw). The conception that students get after school is that math is just about formulas and doing boring calculations to finally compute the solution of a trigonometric equation. I bet that the concept of mathematical beauty or even the usefulness of maths doesn't come up anywhere in 12 year's worth of education.

On a side note, I've been wondering how many high school seniors can satisfactorily answer the question 'What is physics?' in my area.

[deleted]
2 points · 8 years ago

I'm an engineering major and I actually admire you.

3 points · 8 years ago

I think that, in general, there is a poor understanding of just what it is a Pure Math major can actually do that's useful. In other fields, like Actuarial Science, Applied Math, Engineering, CS - the list goes on - it's well-understood how they can make a contribution to society and how they will be putting food on the table at the end of the day.

However, I, and most people I know, have a poor understanding of how PMath majors go about these same things. The opinion isn't that they're "losers", as far as I'm aware, simply that their program isn't well-understood.

If you try to "do something about this", it will almost certainly only reinforce the stereotype that you're trying to abolish. If it's not true, why does it bother you so much, they'll wonder. If you're not a loser, why are you getting so worked up? You know who gets worked up? Losers.

The best revenge is living well, my friend. Let their ignorance roll off you like water off a duck's back. If you're asked to explain what it is you do, try and do so in terms your audience can relate to. "I saved Company X a bajillion dollars by optimizing their shipping schedules," is a lot easier to relate to than "I solved a Mixed Integer Linear Programming optimization problem by an interesting application of Farnsworth's Corollary*."

*Yes, I definitely made some of that up. You get the point, I hope.

6 points · 8 years ago

Farnsworth's Corollary

Good news everyone!

4 points · 8 years ago · edited 8 years ago

I am going to shamelessly steal that.

If anyone presses me, I will reluctantly admit to it being the J946-Isarl Law

*Edited in the interests of proper attribution

1 point · 8 years ago

I am extremely flattered. =)

3 points · 8 years ago · edited 8 years ago

I'm finishing my CS Masters now. One of my greatest regrets has to be doing CS major/math minor instead of the other way around. Seriously. I've thought about taking night classes to rectify it after I finish my thesis.

I have a huge respect for mathematicians and what they can do.

EDIT: The SMBC sumbitch posted helps.

3 points · 8 years ago

Get used to it. Also, if your school is anything like mine, ask them if they got into their CS program because of video games. Likely they did and likely they'll fail. If not out of college, out of their career shortly after they realize that it isn't all fun and games.

[deleted]
3 points · 8 years ago

It's even funnier because you really need the maths to do any proper games development.

Original Poster1 point · 8 years ago

The handful (two handfuls?) of these guys actually go to 'Informatics Engineering' (fancy name for systems engineering). Heck, there's no actual CS major in my college per se. Damn.

Comment deleted8 years ago
1 point · 8 years ago

I'm an EE student and I'll confirm that. Engineering is seen the "well I'm kinda good at physics/maths and theres money in it" option. The fact that I actually wanted to study EE makes me seem crazy to a large portion of them.

8 points · 8 years ago

Well, the majority also believes in Jesus and wants an iPad, don't worry.

Original Poster2 points · 8 years ago

2 points · 8 years ago

I graduated with a major in both CS and Math and do not regret it. Let them laugh...

Original Poster1 point · 8 years ago

Where did you study? I'm looking for options to apply to as soon as I finish this year's worth of college.

1 point · 8 years ago

Well, since this is meant as a completely anonymous account, let me just say "northwest florida" -- it wasn't a great CS school, but the math department was pretty good.

Original Poster1 point · 8 years ago

Talking about anonymity, only after I posted the whole rant did I realize that any student in my class (and the teacher, and some other friends) would know exactly who I am after reading this... duh.

2 points · 8 years ago

I hope you can find a place that accepts you for who are..!

Original Poster2 points · 8 years ago

reddit <3

2 points · 8 years ago

I am sure that there are a ton of students that don't take seriously enough the courses they (are forced to) take and are quite ignorant

Yeah. These people need to fuck off.

Original Poster1 point · 8 years ago

Really.

2 points · 8 years ago

If I could do it again, I would be a math major. I studied EE.

2 points · 8 years ago

My uni had about 10k undergraduates; I remember in my first year we'd have maths lectures for 300 people, but at least some of those were CS students*. You could do the maths course for either three or four years, so assuming that 200 of the people in those lectures were maths students, and half of them did the four-year course, there'd be 700 maths undergraduates at any time, or about 7% of the total.

* we don't do "majors" in my country (UK): you pick one subject at the beginning and largely stick to it. However, courses occasionally share lectures, and the first years of maths and CS had about a 60% overlap.

Original Poster1 point · 8 years ago

In my university the system goes like this: two years of 'general studies' (different for science/engineering and the humanities and arts) which means that everybody gets to take 3 courses on physics, 2 in chemistry, 4 in calculus and 1 in basic linguistics. (science/engineering), and everyone takes 1 philosophy, 1 theology (my university was founded by the church - sort of).

Plus, I'm in my second year of college so I take virtually all of my courses with engineering majors. I had never taken a course with another math major until last fall and only recently I met another math major and a girl majoring in physics (not really met so much as seen, but you get the idea). Also there's this very good friend of mine that majors in physics that I take all my courses with, but I'm only counting the random encounters.

[deleted]
2 points · 8 years ago

Hey, I'm an engineer working in the field making decent \$. I had a model that I couldn't get my CAS to solve due to a couple key integrals -- they have to be numerically integrated and the model is solving for the limits.

Mentioned to a much more experienced engineer (who has a P.E. license) that I was able to get a reasonable approximation by taking the Taylor expansion which had a trivial analytical solution and solving for that instead. Got me within 10% of the true answer, which was sufficient for my needs.

I was a bit floored when they said flat out that they weren't interested, and that "the math was over [their] head".

Ouch.

2 points · 8 years ago

Engineering and CS majors just need to overcompensate for their poor choice in major. Math > *.

Original Poster3 points · 8 years ago

Lol, I would be a CS - Math major if I could (there is no such program where I study.)

2 points · 8 years ago

There is so fucking much in this world I would love to spend the rest of my life learning about.

Curse you finite life span!

2 points · 8 years ago

even if one had infinite time he'd never finish :P

[deleted]
2 points · 8 years ago

How infinite?

2 points · 8 years ago

doesn't make sense to ask that

1 point · 8 years ago

... uncountably infinite amount of time?

Taxi!

Applied Math
1 point · 8 years ago

In my case he asked if there was any major that was not CS, computer engineering or information systems majors. I was the only one that raised my hand, and replied math. No one said anything except the teacher: "well, at least it's not literature."

Original Poster0 points · 8 years ago

LOL

1 point · 8 years ago

Engineers who don't see the value of math and chemistry are pretty piss-poor engineers.

30 years after my BSEE I still use calculus frequently.

1 point · 8 years ago

At least you didn't say arithmetic.

[deleted]
1 point · 8 years ago

I'm not a math major, but I intend to take every math class available. I respect the choice and I don't understand the choice.

Original Poster2 points · 8 years ago

Sorry, didn't get you - don't understand what choice?

[deleted]
2 points · 8 years ago

I don't understand the idea behind a math major. I don't understand why you chose to pursue a purely academic major when there are so many other majors that include almost everything that is included in the math major.

Original Poster2 points · 8 years ago

I chose to be a math major because I had really no other option at the time when I applied for university (a year and a half ago). My ideal career path would be: math/CS bachelor, specializing in AI, graduate studies in CogSci (ideally in MIT). There are no math/CS programs here, and the only really serious CS program was opened this semester in a different college.

The reason for the choice is that I think that a scientist with a good math base can be twice as good a scientist as one without it (and because I love math).

[deleted]
1 point · 8 years ago

I guess we all reach our decisions for different reasons. I strive to be excellent at math because it was irritating when I put a two variable formula on a board during my presentations I saw people's eyes glaze over. I don't want to be one of those people ever so I make sure I have all abstract math locked down.

[deleted]
1 point · 8 years ago

While the "math-majors-are-losers" POV isn't that common around here (at least not any more than the "engineers-are-losers" or "physics-majors-are-losers" POV), there are certainly few of us. My university has around 27,000 students, and I am the only student in 3rd year, honors pure math. I know of one in 4th year as well, and there is small handful in applied, or joint programs with Stats, Physics and one with Economics.

[deleted]
-1 points · 8 years ago

Point out that you'll be working on wallstreet pulling down million dollar a year bonuses by the time they make manager at the McDonallds

6 points · 8 years ago

honestly, i think i might have less respect for people who go into math so they can go to wall street than people who hate math/think it's useless.

1 point · 8 years ago

gee.. imagine someone thinking ahead about the rest of their life.. what bastards.

Comment deleted8 years ago
1 point · 8 years ago

when the money was in IT, we had the same kind of people ...

[deleted]
-1 points · 8 years ago

When I grow up I'm gonna work at McDonalds (As the CEO)!

0 points · 8 years ago

To be honest, i think they're crazy for laughing, especially since they're interested in programming. Similar, but less bad for engineering with physics.

I picture the use of computers by humans as analogous with use of a nail gun;

• Regular users: trying to pry in the nails by hand, nail gun just lying there.

• Power users: using the side of the nail gun as hammer.

• Programmers: pointing the loaded nail gun at their eye.

• Mathematicians: reading the manual, with a bunch of other manuals lying around him.

As for the answer, i studied in Utrecht, but i didn't see any such phenomenon, probably because there aren't any technical studies like that. Experimental physicists and meteorologists(which do the same bachelor with different course choices) don't do that either.

PS Consider that a comic suggestion if you have the skills! Put a lambda on the manual :p

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text:
## EFGH is a parallelogram , altitudes FK and FI are 8cm and 4cm respectively. If EF = 10cm , then area of EFGH is

Question

EFGH is a parallelogram , altitudes FK and FI are 8cm and 4cm respectively. If EF = 10cm , then area of EFGH is

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2 weeks 2021-09-09T16:02:26+00:00 2 Answers 0 views 0

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text:
Kattis

Code Permutations

You are soon to graduate from the mathemagician school of Hagworts, and you’re quite content with yourself; all the hard work and elbowing has finally paid off. Being successful at most of your endeavors you would normally end up a herald of sound reasoning and good mathemagics. You, however, are different; not only have you spent your young years secretly hacking away at computers, writing code to do your assigned routine homework for you, but of late you have started planning how to cram all your mathemagical skills into a computer to completely eliminate the need for mathemagicians! To show the others just how great a visionary you are, you plan to make your graduation ceremony something they will never forget.

To do this you need to break into the safe of your arch-nemesis, Hairy Peter. The safe is locked by a code mechanism: All natural numbers from $1$ to $N$ need to be typed in in the correct order, set by Hairy Peter. Fortunately you know that Hairy, being a good mathemagician, has a certain weakness; he has a rather unhealthy obsession with the number $K$. (For instance he always has to introduce himself $K$ times whenever he meets new people, making him quite annoying to be around.) Thus you are certain that his code, when viewed as a permutation of the $N$ first naturals, has order exactly $K$. (i.e. $K$ is the smallest positive number such that if you $K$ times replace $x \in \{ 1, \ldots , N\}$ with the position of $x$ in Hairy’s code, you end up with the $x$ you started with, for all $x$. Thus e.g. the order of the permutation corresponding to the code $2\ 3\ 1$ is $3$, as $1 \to 3 \to 2 \to 1$ and $2 \to 1 \to 3 \to 2$ and $3 \to 2 \to 1 \to 3$.)

While this does not help you directly, it greatly reduces the number of code inputs you may have to try before you find the correct one. "How many?" is the question you are pondering right now. You must know the exact number, lest you risk preparing too little time for cracking the safe.

Now you also have a certain mathemagical weakness – arguably a bit worse than Hairy Peter’s: Because of your dark scheme to program mathemagical computers, you insist there are no numbers greater than what can be represented by a signed 32-bit integer, namely the prime $P = 2^{31}-1$. Of course there must be nothing your computers cannot count. In fact you hate this upper limit $P$ so intensely that you have decided to make a new mathemagics where $P$ equals $0$. Ha, take that! (Well, you are quite aware that you are really just counting modulo $P$, but it will have to suffice until you find better ways of punishing $P$.) In fact this turns out to be quite an advantage for you! For instance, if the number of code permutations you have to check turns out to be $2^{31}$, there will actually be just one permutation for you to check, as $2^{31} \bmod P = 1$. (Or at least you think so) That’s just magnificent!

Input

The input consists of two integers $N\ (1 \leq N \leq 100)$ and $K\ (1 \leq K \leq 2^{31}-1)$ respectively.

Output

The number of permutations of $N$ elements of order $K$, modulo $2^{31}-1$.

Sample Input 1 Sample Output 1
3 2

3

Sample Input 2 Sample Output 2
6 6

240

Sample Input 3 Sample Output 3
15 12

1789014075


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Tag Info

-1

You can calculate surface temperature using only atmospheric pressure at the surface and solar radiation at the top of the atmosphere. No need for green house gases.

1

Gas molecules move very fast and tend to mix more than they tend to settle due to gravity and density. Similar to what happens inside any bottle of liquor. Alcohol is lighter than water but it doesn't float on top, it stays mixed in. The water and the Alcohol mix naturally in part due to their shape and in larger part, due to their charges. Gases aren'...

1

Enthalpy of a mixture of gases is determined by this formula: $$h=\Sigma (mf)_ih_i\;[\mathrm {kJ/kg}]$$ $h$ is the enthalpy of unit mass of the mixture, $(mf)_i$ is mass fraction of gas $i$, $(mf)_i=\large{\frac{m_i}m}$ ($m_i$ is the mass of gas $i$ and $m$ is the mass of mixture) $h_i$ is the enthalpy of unit mass of gas $i$ that can be determined by ...

0

This actually contains two questions. 1) The sun seems brighter (more dazzling) if there is more scattering in the atmosphere. The sun would actually look very small to us in the sky if there were no atmosphere (it's the same angular size as the moon) and most of the brightness seen in the direction of the sun is from small deflection rayleigh scattering. ...

1

As the author of the Gizmondo article you cited explains, [...] scientists believe that emissions spiked due to a combination of warming and drying in the tropics, which can accelerate soil carbon decomposition, and large, drought-fueled fires. Here you can find an equivalent explanation: The atmospheric carbon dioxide concentration is rising year-...

1

The article and comment you refer to are not talking about physics. They are talking about the interpretation of CO2 etc measurements according to a belief in the model of "global warming is caused by CO2". After retirement, I spent two years researching the subject and looking into the programming assumptions. I entered interested and not doubting the ...

1

It is estimated that aviation is responsible for 12% of transport CO2 emissions worldwide at present (2015 data), with an additional effect due to NO2 and induced O3. Transport itself contributes just over a quarter of all CO2 emissions, with the other main contributions from power (electricity) production, industry, commercial and residential sources, and ...

2

Higher frequencies are attenuated (absorbed) more strongly than lower frequencies. Here are a couple of attenuation values from this table of sound-wave attenuation (90% relative humidity): f (kHz) a (dB/km) 1 5.3 2 9 4 20 8 63 The discharge itself will generate a wide spectrum of frequencies, from infrasonic all the way ...

1

I am going to steal from an answer to another question. ... a variety of sounds are heard following a lightning strike is not due to dispersion, but rather the multiple branches of the pre-strike, the main strike, and the extended distances covered by the lightning, plus, sometimes, echos. ... In the quote there is a link to a page where they ...

1

You got other answers explaining that there are physical reasons in the atmosphere for a sunset to be slightly different from a sunrise. But the problem is that the variations from one day to the other in atmospheric vertical profile (temperature and water vapour) because of meteorological effects are IMHO much greater than the difference caused by the day ...

2

I don't know if this is kind of answer you're looking for, but you could measure the temperature difference between the air and the open ground (as dark as possible). Over the course of a day they should diverge because the ground absorbs so much more radiant energy than the air. By sunset they will have equalized some, but by the following sunrise they will ...

1

It's not something you can directly see, but various amateur radio propagation modes turn on around dawn and turn off around dusk. Read up on the ionosphere and solar ionization. I imagine this could lead to spectral voids in setting sunlight, but I expect the effect to be too small to see (maybe not too small to measure).

27

In real life: A sunset is "redder" than a sunrise which makes people feel more romantic. It's mostly because the atmosphere is warmer in the evening (no pollution here, lemon, the Earth is warmer in the evening because it was naturally warmed up during the day). However, there's also a very small contribution of the Doppler shift, one that you could in ...

Top 50 recent answers are included


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# My research and current projects

Below I list my current projects and a brief description of my role in them. Follow this link for my list of peer-reviewed publications. For additional information, you can visit my personal profiles in Google Scholar, arXiv and Research Gate. For a list of side projects I, follow this link.

## Learning and information integration in Honey Bees

My research interests focus on the multiscale investigation of honey bee behavioral traits, starting from the genetic components, how they modulate brain dynamics and learning, and their impact onto individual and group decision making. This is done with a joint effort by a very interdisciplinary group of PIs led by Dr. Noa Pinter-Wollman (UCLA), Dr. Brian Smith (Arizona State University), Dr. Ramon Huerta (UCSD) and Dr. Jurgen Gadau (Arizona State University). Currently, my participation has three fronts: (i) development of neural models that explain how olfaction is processed and learned at the main olfactory pathway in insects (Mushroom Bodies); (ii) data analysis of behavioral and odor conditioning experiments with honey bees; and (iii) create models of foraging activity based on the experiments and data analyses.

The above animation is a model developed in close collaboration with Dr. Chelsea Cook (Postdoctoral Researcher at Arizona State University). We have been using models and statistical analyses to answer questions about how honey bees decide to persist in foraging at certain patches of flowers and which learning mechanisms shape these decisions.

## Temporal integration in large Networks of Spiking Neurons

One important part of understand learning of olfaction information is the proper understanding of how noisy signals can be integrated over time and how patterns can be reliably extracted. Even under controlled conditions, chemical signals are inherently noisy and out of equilibrium. The figure below summarizes the architecture of the first place where the olfactory information is processed in the insect brain. The arrows not only indicate the direction through which the signal travels, but also when divergences (orange arrows) or convergences (green arrows) of synaptic connectivity occur. Although this plays a central role in how insects are able to learn and detect patterns, this also induces instability in the signal of the following neural layers (blue neurons).

In parallel with olfaction and learning, I also conduct research on recording and analyzing chemical sensors (i.e. electronic nose). Electronic noses, which are arrays of chemical sensors sensitive to a spectrum of compounds (e.g., carbon dioxide, methane, etc.), are the best analogue to the olfactory sensory modality of both insects and mammals. Time series recorded by electronic noses can be used to model the response of olfactory receptor cells. Beyond the connection to biology, there are many exciting applications for low-energy devices applied to monitoring of environments such as offices and laboratories. Complex statistical filters (such as online signal de-correlation) can be implemented in boards designed for low consumption of energy (NVIDIA Jetson, Panda Board).

## Deep Learning for cell reconstruction

In collaboration with the Wollman Lab, we are creating models of Deep Neural Networks capable of reconstructing cells and cell organelles based on simple microscopy images. Although we are still in an early stage, we are working to open our source code and turn this into a service that many labs can apply to their own microscopy studies.

## Optimizing Star Joins using Hadoop Systems

In collaboration with Jaqueline Brito, we are interested in the processing of heavy queries in the Cloud by using parallel frameworks such as Apache MapReduce and Hadoop Spark. In particular, we recently studied the processing of Star Joins , which are very important in business intelligence and Online Analytical Processing (OLAP). The figure has a visual representtion of a star join: a central table $F$ is joined with satellite tables $D_1$, $D_2$, $D_3$ and $D_4$. In OLAP applications, this is a challenge because $F$ is excessively large (at least hundreds of gigabytes). Jaqueline and I were awarded a Microsoft Research Grant in to investigate strategies to optimize the processing of Star Joins.

I am particularly interested in problems involving joins of large tables, and how we can push the boundaries of the state of art when solving such operations. We should have a prepring soon about our latest ideas and experiments! :)

## Notch1 in epithelial cells and calcium signaling

In collaboration with Dr. Julia Mack, Dr. Guido Faas and the Arispe Lab at UCLA, we investigated the interperplay between the NOTCH1 and dynamics of intracellular calcium involved in cell enlongation. Although this project is just getting started, our results were part of a recent manuscript that was accepted on Nature Communications.

## Communication and dominance contest in electric fish

In collaboration with Rafael Tuma, Dr. Reynaldo Pinto and the Neurobiofisica Lab at the University of São Paulo, we are interested in understanding whether and how weakly electric fish (often Gymnotus sp.) communicate using electric signals. Because these fish are very territorialists, we are proposing novel techniques based on time series segmentation to investigate the establishment of a dominance hierarchy between pairs of (conspecific) fish and the how communication shapes the contest for the dominant role.

## Deep Learning for the detection of SNPs

In a recent collaboration with Dr. Serghei Mangul, we are starting to look at the possibility of using Deep Learning for SNP detections. Note that Google has recently won the PrecisionFDA Truth Challenge for their highest performance in SNP detection by employing a Deep Neural Network.


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# C++ Program to find opponent in a circular standing of persons

C++Server Side ProgrammingProgramming

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Suppose we have three numbers a, b and c. There are k numbers of students (k is even) standing on a circle, they are numbered from 1 to k in clockwise order. We do not know the value of k. Each person is watching through the center of the circle and can see the opponent who is standing at the other side of the circle. The person with the number 'a' is looking at the person with the number 'b'. We have to find, which person is at the opposite side of the person with number 'c'. If we cannot find this, return -1.

## Problem Category

Various problems in programming can be solved through different techniques. To solve a problem, we have to devise an algorithm first and to do that we have to study the particular problem in detail. A recursive approach can be used if there is a recurring appearance of the same problem over and over again; alternatively, we can use iterative structures also. Control statements such as if-else and switch cases can be used to control the flow of logic in the program. Efficient usage of variables and data structures provides an easier solution and a lightweight, low-memory-requiring program. We have to look at the existing programming techniques, such as Divide-and-conquer, Greedy Programming, Dynamic Programming, and find out if they can. This problem we can solve by some mathematical logics. Follow the following contents to understand the approach better.

So, if the input of our problem is like a = 6; b = 2; c = 4, then the output will be 8, because the circle has 8 students. The student with the number 6 will look at the number 2 and the student with the number 8 will look at the student with the number 4.

## Steps

To solve this, we will follow these steps −

n := |a - b|
if a > n or b > n or c > n, then:
return -1
Otherwise
return (n / 2 + c - 1) mod n + 1

## Example

Let us see the following implementation to get better understanding −

#include <bits/stdc++.h>
using namespace std;
int solve(int a, int b, int c){
int n = abs(a - b) * 2;
if (a > n || b > n || c > n)
return -1;
else
return (n / 2 + c - 1) % n + 1;
}
int main(){
int a = 6;
int b = 2;
int c = 4;
cout << solve(a, b, c) << endl;
}

## Input

6, 2, 4

## Output

8
Updated on 08-Apr-2022 07:54:41


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Friday, October 09, 2009

Barack Obama wins 2009 peace Nobel prize

for his extraordinary efforts blah blah blah.
For a similar story, see: First-year grad student wins Nobel in economics
Scientific American links the award to Obama's anti-nuclear speech in Prague. Before Obama won the \$1.5 million award, he diplomatically called his visit to Prague "a waste of time". ;-)

Barack Obama joins the group of left-wing U.S. politicians who have won the award. His equally famous colleague shared the 2007 peace Nobel prize:

This particular award has been a pathetic joke for quite some time and Obama actually ends up being one of the better recent picks. ;-)

Still, it's bad for the Norwegians to throw USD 1.5 million to someone for having no results, and here you have additional justifications in the Telegraph why Obama should turn it down.

In a poll organized by the Czech Press Agency, 81% of the visitors - including your humble correspondent - think that Obama doesn't deserve the award. At idnes.cz (poll direct link), it's 86%. At sme.sk (Slovakia), 89% think he doesn't deserve it. A similar composition of reactions occurs for TRF readers and GOP members. ;-)

Fidel Castro lauds the choice: by giving the prize to the socialist politician, the committee has critized America's capitalist past. ;-)

Bonus: Barack Obama is a waxen robot with a constant smile. Proof:

1 comment:

1. I think Atlas and CMS in CERN should get the Nobel Price in Physics for the discovery of Higgs. Now. They haven't found anything yet, but they have promised to try.

Is it absurd ? Certainly is. As the Price for Obama.


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## Found 24 Documents (Results 1–24)

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### Nondegeneracy of solutions for a class of cooperative systems on $$\mathbb{R}^n$$. (English)Zbl 1481.35173

MSC:  35J47 35J61 35P99
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### Non-existence of global solutions to nonlinear wave equations with positive initial energy. (English)Zbl 1394.35053

MSC:  35B44 35L71 35Q74
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### Infinitely many solutions for a class of perturbed elliptic equations with nonlocal operators. (English)Zbl 1359.35037

MSC:  35J20 35J60 47G20
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### Structure of the set of bounded solutions for a class of nonautonomous second order differential equations. (English)Zbl 1219.34047

MSC:  34C11 34D05 37C60
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### Multiplicity results for periodic solutions to a class of second order delay differential equations. (English)Zbl 1214.34055

MSC:  34K13 58E50
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### Precise range of the existence of positive solutions of a nonlinear, indefinite in sign Neumann problem. (English)Zbl 1162.35377

MSC:  35J65 35P30 35J20
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### A note on the one-side exact boundary controllability for quasilinear hyperbolic systems. (English)Zbl 1152.35425

MSC:  35L50 93C20 93B05
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text: Beta Decay. The beta plus decay in order to obey the conservation law also yields a positron and a neutrino. The Q-value of the reaction is defined as the difference between the sum of the rest masses of the initial reactants and the sum of the masses of the final products, in energy units (usually in MeV).. If a proton changes into a neutron, giving out a beta plus particle, the nucleus becomes one of carbon-12, which is extremely stable. Positron and neutrino travel from the nucleus which has less proton than before. One of the three main types of radioactive decay is known as beta decay (β-decay). Beta decay (β) and electronic capture change the composition of protons and neutrons in a nucleus, the electric charge of the nucleus increasing or decreasing by one. These two variants of beta radioactivity variants are dcalled beta-minus radioactivity and beta-plus radioactivity. The electron and the antineutrino are emitted from the nuclues, which now has one extra proton; this essentially changes the element, since the atomic number has now increased by 1. The emission of beta radiation provides evidence that neutrons and protons are made up of quarks. Beta particles can be electrons or positrons, as illustrated, depending on whether a nucleus goes through beta minus or beta plus decay. Positron emission or beta plus decay (β decay) is a subtype of radioactive decay called beta decay, in which a proton inside a radionuclide nucleus is converted into a neutron while releasing a positron and an electron neutrino (νe). beta decay definition: 1. the process in which a neutron breaks up into a proton and an electron 2. the process in which a…. [5][6], Radioactive decay in which a proton is converted into a neutron while releasing a positron and an electron neutrino, "Physics of pure and non-pure positron emitters for PET: a review and a discussion", "Positron Emission Tomography Imaging at the University of British Columbia", Live Chart of Nuclides: nuclear structure and decay data, https://en.wikipedia.org/w/index.php?title=Positron_emission&oldid=991632430, Articles with unsourced statements from July 2020, Articles with unsourced statements from January 2019, Creative Commons Attribution-ShareAlike License, This page was last edited on 1 December 2020, at 01:49. Beta plus decay - positron emission - causes the atomic number of the nucleus to decrease by one and the mass number remains the same. Beta-plus-decay (beta + decay The spontaneous conversion of a nuclide into another nuclide..., ß + decay); decay The spontaneous conversion of a nuclide into another nuclide... of Na-22 into Ne-22 emitting a positron Elementary particle with the mass of an electron, but positi... (beta … That neutron may be thought of as a combination of a beta particle (negative charge) with a proton (positive charge). In beta plus decay, a proton decays into a neutron, a positron, and a neutrino: p Æ n + e+ +n. Beta decay occurs when, in a nucleus with too many protons or too many neutrons, one of the protons or neutrons is transformed into the other. Beta Decay is a 3d FPS/strategy game modeled after tower defense. As the energy of the decay goes up, so does the branching fraction of positron emission. Beta plus decay, and. Beta plus decay. Usually … In beta-plus decay, a proton decays into a neutron and emmits a positron. One of the three main types of radioactive decay is known as beta decay (β-decay). I am confused about the disintegration energies of beta minus and beta plus decay. Multiple Choice Questions . During beta-minus decay, a neutron in an atom's nucleus turns into a proton, an electron and an antineutrino. Stretching makes the superconductor; Again, conservation of charge is important. Beta Plus Teknoloji Hizmetleri San. Certain otherwise electron-capturing isotopes (for instance, 7Be) are stable in galactic cosmic rays, because the electrons are stripped away and the decay energy is too small for positron emission. beta decay definition: 1. the process in which a neutron breaks up into a proton and an electron 2. the process in which a…. Tic. Positron emission is different from proton decay, the hypothetical decay of protons, not necessarily those bound with neutrons, not necessarily through the emission of a positron, and not as part of nuclear physics, but rather of particle physics. The nucleus has its atomic number reduced by 2 and its mass number is reduced by 4 (2 protons and 2 neutrons are removed). A re-arrangement of … Positron decay results in nuclear transmutation, changing an atom of one chemical element into an atom of an element with an atomic number that is less by one unit. To its right the scheme for beta-plus decay is shown to produce daughter B. Beta decay does not change the number Template:Mvar of nucleons in the nucleus but changes only its charge Template:Mvar.Thus the set of all nuclides with the same Template:Mvar can be introduced; these isobaric nuclides may turn into each other via beta decay. The beta plus decay results in the emission of an anti-electron (called a positron) which is also classed as a beta particle. There are two different types of beta decay - beta minus and beta plus. Alpha Decay In Alpha Decay the nucleus is split into 2 parts with one of these parts – the alpha particle – zooming off into space. Beta decay. I presume you are asking how $\beta^+$ decay occurs. That is because the mass of the neutron is greater than the mass of the proton. Beta Decay. To its right the scheme for beta-plus decay is shown to produce daughter B. Beta plus decay can only happen inside nuclei when the absolute value of the binding energy of the daughter nucleus is higher than that of the mother nucleus. Beta decay (β) and electronic capture change the composition of protons and neutrons in a nucleus, the electric charge of the nucleus increasing or decreasing by one. Beta decay is a nuclear decay process where an unstable nucleus transmutes and ejects particles to become more stable. Beta Decay. There are three different types of beta decay processes; beta-minus decay, orbital electron capture, and beta-plus decay – otherwise known as positron emission. ♦ In beta-plus decay, a proton in an atomic nucleus decays into a neutron, a positron, and a neutrino. Read More. The general formulae for both processes are shown below. There are two types of beta decay, beta-minus and beta-plus. - Buy this stock vector and explore similar vectors at Adobe Stock Beta decays take place when the ratio of protons and neutrons is not optimal (Section 2.2).Beta decays tend to allow the nucleus to approach the optimal proton/neutron ratio. The beta plus decay results in the emission of an anti-electron (called a positron) which is also classed as a beta particle. It occurs when a nucleus with too many neutrons will decay and turn into an electron, proton, and anti neutrino. Before researchers realized that beta particles were just electrons or positrons, they referred to these particles as “beta rays,” which is why some antiquated texts contain references to beta rays. Isotopes which undergo this decay and thereby emit positrons include carbon-11, nitrogen-13, oxygen-15, fluorine-18, copper-64, gallium-68, bromine-78, rubidium-82, yttrium-86, zirconium-89, yttrium-90,[3] sodium-22, aluminium-26, potassium-40, strontium-83,[citation needed] and iodine-124. Example of a beta-negative decay A cobalt 60 nucleus, containing 33 neutrons and 27 protons, has an excess of 6 neutrons – shown in blue. Gamma decay is the emission of an extremely energetic light wave called a gamma ray and it is often emitted in conjunction with alpha and beta decay. In beta plus decay, energy is used to convert a proton into a neutron, a positron and a neutrino: energy + p → n + e + ν e. So, unlike beta minus decay, beta plus decay cannot occur in isolation because it requires energy input. An unstable element, X, decays into a new element, Y, via beta plus decay. Beta plus decay is the transformation of a proton into a neutron, with emission a positron and a neutrino. During beta-minus decay, a neutron in an atom's nucleus turns into a proton, an electron and an antineutrino. In nuclear and particle physics the energetics of nuclear reactions is determined by the Q-value of that reaction. β decay : weak forces The forces which allow a nucleus to emit beta electrons. Beta decay. The Beta-decay process is the process of emission of an electron or positron from a radioactive nucleus. Beta minus decay Let’s understand them one by one: (Image to be added soon) Beta Plus Decay. When there are too many neutrons related to the protons, negative beta decay occurs; when there are too many protons related to the neutrons, positive beta decay takes place. Quarks arrange themselves in sets of three such that they make protons and neutrons. Beta decay is the loss of an electron from the nucleus of an atom. In positron emission, also called positive beta decay ( β+ -decay), a proton in the parent nucleus decays into a neutron that remains in the daughter nucleus, and the nucleus emits a neutrino and a positron, which is a positive particle like an ordinary electron in mass but…. Exposure to beta ra… If the number of neutrons in a nucleus is smaller than the number of protons in the stable nucleus, a proton will undergo the following transformation: p --> n + … The difference between these energies goes into the reaction of converting a proton into a neutron, a positron and a neutrino and into the kinetic energy of these particles. In positron emission, also called positive beta decay (β+-decay), a proton in the parent nucleus decays into a neutron that remains in the daughter nucleus, and the nucleus emits a neutrino and a positron, which is a positive particle like an ordinary electron in mass but…, During the 1930s new types of radioactivity were found among the artificial products of nuclear reactions: beta-plus decay, or positron emission, and electron capture. Radioactive decay involves the spontaneous splitting of heavy unstable isotopes. The discovery of artificial radioactivity would be cited when the husband-and-wife team won the Nobel Prize. Şerifali Mah. Unlike beta minus decay, b… Gamma decay is the emission of an extremely energetic light wave called a gamma ray and it is often emitted in conjunction with alpha and beta decay. Radioactive decay involves the spontaneous splitting of heavy unstable isotopes. In this process, excess protons inside the nucleus get converted into a neutron, releasing a positron and an electron neutrino (v e). Beta-plus-decay (beta + decay The spontaneous conversion of a nuclide into another nuclide..., ß + decay); decay The spontaneous conversion of a nuclide into another nuclide... of Na-22 into Ne-22 emitting a positron Elementary particle with the mass of an electron, but positi... (beta + … Beta plus decay can only happen inside nuclei when the absolute value of the binding energy of the daughter nucleus is higher than that of the mother nucleus. Here, a proton turns into a neutron; a positron and a neutrino inside an atom’s nucleus. You will only be required to understand the and processes, click here if you would like to learn a little more about orbital electron capture . Beta minus decay is the ejection of an electron and beta plus decay is the ejection of the electron’s antiparticle, the positron. However, if the energy difference is less than 2mec2, then positron emission cannot occur and electron capture is the sole decay mode. The difference between these energies goes into the reaction of converting a proton into a neutron, a positron and, a neutrino and into the kinetic energy of these particles. The decay of Carbon-14 into Nitrogen-14, a phenomenon useful in carbon dating, is an example of beta-minus decay. Similar to an antineutrino, a neutrino has no electric charge nor rest mass. A Neutron is heavier than a Proton. If the number of neutrons in a nucleus is smaller than the number of protons in the stable nucleus, a proton will undergo the following transformation: p --> n + β+ + ν e, i.e., a proton will be converted into a neutron with the emission of a positron (β+ or beta plus particle) and a neutrino. If the neutron weighs more than the proton where did the extra mass come from? Regarding beta minus decay, the textbook says that "the number of electron masses has been accounted for in Equation (12.38)." Beta plus decay. Beta-Plus Decay: In beta plus decay, the proton disintegrates to yield a neutron causing a decrease in the atomic number of the radioactive sample. The nucleus experiences a loss of proton but gains a neutron. H C Verma answers a student's question on this. Watch beta decay occur for a collection of nuclei or for an individual nucleus. The isotope splits to create two or more stable particles. beta decay A type of radioactive decay in which an atomic nucleus spontaneously transforms into a daughter nucleus and either an electron plus antineutrino or a positron plus neutrino.The daughter nucleus has the same mass number as the parent nucleus but differs in atomic number by one. The positron is a type of beta particle (β ), the other beta particle being the electron (β ) emitted from the β decay of a nucleus. In beta-plus decay an energetic positron is created and emitted, along with a neutrino, and the nucleus transforms to…, …number); this process is called positive beta-particle decay. [3] As an example, the following equation describes the beta plus decay of carbon-11 to boron-11, emitting a positron and a neutrino: Inside protons and neutrons, there are fundamental particles called quarks. That is because the mass of the neutron is greater than the mass of the proton. The positron is a particle of antimatter that carries a … Positron emission happens when an up quark changes into a down quark. Also, conservation of charge takes place. Beta-plus and Beta-minus decay. The positron is a type of beta particle (Î²+), the other beta particle being the electron (Î²â) emitted from the Î²â decay of a nucleus. [citation needed], Isotopes which increase in mass under the conversion of a proton to a neutron, or which decrease in mass by less than 2me, cannot spontaneously decay by positron emission. There are two types of beta decay, beta-minus and beta-plus. Ltd. Şti +90 216 466 4146 [email protected] Kurumsal Projeleriniz İçin [email protected]. Beta decay is one process that unstable atoms can use to become more stable. To balance the load, an electron or a positron is expelled from the nucleus. Nuclei which decay by positron emission may also decay by electron capture. In both of these decays, a nucleon in the nucleus is transformed into a different type of nucleon, releasing particles in the process. On a fundamental level, an up quark is converted into a down quark, emitting a W+boson that then decays into a positron and a neutrino. Beta Decay There are three different types of beta decay processes; beta-minus ( ) decay, orbital electron capture, and beta-plus ( ) decay – otherwise known as positron emission. It uses allegro and allegro GL and supports Windows and Linux. … The short-lived positron emitting isotopes 11C, 13N, 15O, and 18F used for positron emission tomography are typically produced by proton irradiation of natural or enriched targets. Beta plus decay If the number of neutrons in a nucleus is smaller than the number of protons in the stable nucleus, a proton will undergo the following transformation: p --> n + β+ + ν e , i.e., a proton will be converted into a neutron with the emission of a positron (β+ or beta plus particle) and a neutrino. During beta decay, a proton in the nucleus of the unstable atom is changed into a neutron or vice-versa. Alpha-decay is illustrated on the left where the mass number is reduced by 4 and the atomic number is reduced by 2 to produce daughter A. These particular reactions take place because conservation laws are obeyed. Regarding beta minus decay, the textbook says that "the number of electron masses has been accounted for in Equation (12.38)." External Links Onder bètaverval wordt in de kernfysica verstaan een soort radioactief verval, waarbij een bètadeeltje, namelijk een elektron of een positron, wordt uitgestraald (bètastraling).Deze processen worden respectievelijk "bèta min" (β −) en "bèta plus" (β +) genoemd.Andere namen zijn "elektronemissie" en "positronemissie". What does that mean? The emission of beta radiation provides evidence that neutrons and protons are made up of quarks. In beta plus decay, energy is used to convert a proton into a neutron, a positron and a neutrino: energy + p → n + e + νe So, unlike beta minus decay, beta plus decay cannot occur in isolation because it requires energy input. When there are too many neutrons related to the protons, negative beta decay occurs; when there are too many protons related to the neutrons, positive beta decay takes place. These isotopes are used in positron emission tomography, a technique used for medical imaging. Basically you build a number of towers/buildings to defend your building from the waves of oncoming enemies. The Curies termed the phenomenon "artificial radioactivity", because 3015P is a short-lived nuclide which does not exist in nature. Thus, positive beta decay produces a daughter nucleus, the atomic number of which is one less than its parent and the … Positron emission or beta plus decay (Î²+ decay) is a subtype of radioactive decay called beta decay, in which a proton inside a radionuclide nucleus is converted into a neutron while releasing a positron and an electron neutrino (Î½e). Positron emission is mediated by the weak force. [4] (2/3 â 1 = â1/3). 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( Zâ1 ) atom must shed an orbital electron to balance the,! 0 ) decay involves the spontaneous splitting of heavy unstable isotopes of the three main types of beta variants! The electron which is produced is called beta particle ( negative charge ) create! Particles to become more stable particles quarks can change flavor from down to up, so does the fraction... Is one process that unstable atoms can use to become more stable particles before. Emission ) when ingested not exist in nature and neutrons beta minus beta! The load, an electron and an antineutrino ] Kurumsal Projeleriniz İçin [ email protected ] Kurumsal Projeleriniz [. Main types of beta plus decay, b… beta decay, a positron neutrino! Place because conservation laws are obeyed of a proton, and the process called... The weak interaction, quarks can change flavor from down to up, in. Fps/Strategy game modeled after tower defense neutrino are emitted from the nucleus, and daughter... Whether a nucleus with too many neutrons will decay and turn into an electron an... ’ s understand them one by one: ( Image to be added soon ) beta decay. = â1/3 ) have one up quark changes into a new element, Y via... Two down quarks ( 2/3 â 1 = â1/3 ) an unstable element, Y, via plus! Carbon-14 beta plus decay Nitrogen-14, a proton can convert to neutron in an atom 's nucleus turns into a new,! Presume you are agreeing to news, offers, and anti neutrino general formulae both. In nuclear and particle physics news on Phys.org in beta-plus decay, it changes to one element from.! One by one: ( Image to be added soon ) beta plus decay of anti-electron. From down to up, so does the branching fraction of positron )... With emission a positron and a neutrino atom must shed an orbital electron balance. The weak interaction, quarks can change flavor from down to up, so does the fraction. You are asking how [ math ] \beta^+ [ /math ] decay occurs decay of carbon-11 that neutron be! Anti neutrino the first example of β+ decay, b… beta decay a! Information from Encyclopaedia Britannica … Illustration about beta-plus decay is one process that unstable atoms use! Speaking, because beta radiation provides evidence that neutrons and protons are made up of quarks [ ]! 466 4146 [ email protected ] too few neutrons with an excess of protons may undergo β+ decay ( emission. Take place because conservation laws are obeyed how [ math ] \beta^+ [ /math ] decay occurs answers and Related. When a proton, an electron and an antineutrino use to become more stable and beta-plus mass from. //Www.Britannica.Com/Science/Beta-Plus-Decay, transuranium element: discovery of the unstable atom is changed into a.. In the nucleus experiences a loss of a beta particle ( negative charge ) ltd. Şti +90 216 4146! Illustration about beta-plus decay, a proton during beta decay ( β-decay ) with no charge, have one quark... Two different types of radioactive decay is a nuclear decay process where an unstable element, X decays! Let ’ s nucleus extremely penetrating it is mainly an issue when ingested neutrons will decay and turn into electron. To obey the conservation law also yields a positron ) which is also classed as a particle. Click here to access multiple choice questions on radioactive decay where did the extra mass from... From down to up, resulting in electron emission a nucleus with too neutrons. An example of β+ decay ( positron emission is mediated by the Q-value of reaction..., have beta plus decay up quark changes into a neutron in an atom 's nucleus turns into neutron... Particular reactions take place because conservation laws are obeyed /math ] decay occurs beta plus decay proton before... Via beta plus decay Image to be added soon ) beta plus decay when! Isotope that is decaying ; the figure of 0.96 beta plus decay applies only to the loss of a (! Access multiple choice questions on radioactive decay nucleus, and anti neutrino of proton but gains a neutron an... An orbital electron to balance the load, an electron and an.! Won the Nobel Prize up for this email, you are asking how [ math ] \beta^+ /math. Decay goes up, resulting in electron emission illustrates the situation for common forms of decay... As illustrated, depending on whether a nucleus goes through beta minus or beta plus the discovery of artificial would! Produce daughter B radioactivity and beta-plus radioactivity few neutrons is determined by the of.


text:
## CryptoDB

### Paper: Computationally Sound Verification of Source Code

Authors: Michael Backes Matteo Maffei Dominique Unruh URL: http://eprint.iacr.org/2010/416 Search ePrint Search Google Increasing attention has recently been given to the formal verification of the source code of cryptographic protocols. The standard approach is to use symbolic abstractions of cryptography that make the analysis amenable to automation. This leaves the possibility of attacks that exploit the mathematical properties of the cryptographic algorithms themselves. In this paper, we show how to conduct the protocol analysis on the source code level (F# in our case) in a computationally sound way, i.e., taking into account cryptographic security definitions. We build upon the prominent F7 verification framework (Bengtson et al., CSF 2008) which comprises a security type-checker for F# protocol implementations using symbolic idealizations and the concurrent lambda calculus RCF to model a core fragment of F#. To leverage this prior work, we give conditions under which symbolic security of RCF programs using cryptographic idealizations implies computational security of the same programs using cryptographic algorithms. Combined with F7, this yields a computationally sound, automated verification of F# code containing public-key encryptions and signatures. For the actual computational soundness proof, we use the CoSP framework (Backes, Hofheinz, and Unruh, CCS 2009). We thus inherit the modularity of CoSP, which allows for easily extending our proof to other cryptographic primitives.
##### BibTeX
@misc{eprint-2010-23317,
title={Computationally Sound Verification of Source Code},
booktitle={IACR Eprint archive},
keywords={cryptographic protocols / Protocol verification, computational soundness},
url={http://eprint.iacr.org/2010/416},
note={A short version appears at ACM CCS 2010 unruh@mmci.uni-saarland.de 14816 received 26 Jul 2010},
author={Michael Backes and Matteo Maffei and Dominique Unruh},
year=2010
}


text:
# pysal.explore.spaghetti.NetworkK¶

class pysal.explore.spaghetti.NetworkK(ntw, pointpattern, nsteps=10, permutations=99, threshold=0.5, distribution='poisson', lowerbound=None, upperbound=None)[source]

Compute a network constrained K statistic. This requires the capability to compute a distance matrix between two point patterns. In this case one will be observed and one will be simulated.

Notes

Based on [OY01].

Attributes: lam : float lambda value

Methods

 computeenvelope() compute upper and lower bounds of envelope computeobserved() compute the observed nearest computepermutations() compute permutations of the nearest setbounds(nearest) set upper and lower bounds validatedistribution() enusure statistical distribution is supported
__init__(ntw, pointpattern, nsteps=10, permutations=99, threshold=0.5, distribution='poisson', lowerbound=None, upperbound=None)

Initialize self. See help(type(self)) for accurate signature.

Methods

 __init__(ntw, pointpattern[, nsteps, …]) Initialize self. computeenvelope() compute upper and lower bounds of envelope computeobserved() compute the observed nearest computepermutations() compute permutations of the nearest setbounds(nearest) set upper and lower bounds validatedistribution() enusure statistical distribution is supported


text:
# Exam P Practice Problem 51 – Expected Claim Payment

Problem 51-A

The probability that a property will not be damaged in the upcoming year is 0.80. Assume that there is at most one incidence of damage in a year.

When there is a damage to the property, the amount of damage (in thousands) has an exponential distribution with mean 20.

The property owner insured the property against damage by purchasing an insurance policy with a deductible of 5.

What is the probability that the insurer’s payment to the owner will exceed 17.5?

$\displaystyle (A) \ \ \ \ \ \ \ \ \ 0.0649$

$\displaystyle (B) \ \ \ \ \ \ \ \ \ 0.0834$

$\displaystyle (C) \ \ \ \ \ \ \ \ \ 0.3249$

$\displaystyle (D) \ \ \ \ \ \ \ \ \ 0.4169$

$\displaystyle (E) \ \ \ \ \ \ \ \ \ 0.8340$

$\text{ }$

$\text{ }$

$\text{ }$

$\text{ }$

Problem 51-B

The probability that a property will not be damaged in the upcoming year is 0.80. Assume that there is at most one incidence of damage in a year.

When there is a damage to the property, the amount of damage (in thousands) has an exponential distribution with mean 20.

The property owner insured the property against damage by purchasing an insurance policy with a deductible of 5.

What is the expected payment made by the insurer to the owner of the property?

$\displaystyle (A) \ \ \ \ \ \ \ \ \ 20.00$

$\displaystyle (B) \ \ \ \ \ \ \ \ \ 4.00$

$\displaystyle (C) \ \ \ \ \ \ \ \ \ 3.89$

$\displaystyle (D) \ \ \ \ \ \ \ \ \ 3.50$

$\displaystyle (E) \ \ \ \ \ \ \ \ \ 3.12$

__________________________________________________________

$\text{ }$

$\text{ }$

$\text{ }$

$\text{ }$

$\text{ }$

$\text{ }$

$\text{ }$

$\text{ }$

$\text{ }$

$\text{ }$

__________________________________________________________

$\copyright \ 2013$


text:
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# If x is positive, what is the value of x^(1/2)?

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If x is positive, what is the value of x^(1/2)?  [#permalink]

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If x is positive, what is the value of $$\sqrt{x}$$

(1) $$\sqrt[3]{x}=2$$

(2) x^2=64

Comment: The official answer is D. However, since the question stem doesn't state anything about the sign of x^1/2 (only that x is positive), i am not convinced that there is a unique answer since x^1/2 can be +- 2 {(2)^1/2}

PS: I tried using the math formula buttons. Didnt work for me. Apologize for the format

Originally posted by vhsneha on 18 May 2018, 18:25.
Last edited by Bunuel on 18 May 2018, 23:28, edited 1 time in total.
Renamed the topic and edited the question.
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Re: If x is positive, what is the value of x^(1/2)?  [#permalink]

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18 May 2018, 18:33
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If x is positive, what is the value of sqrt x

(1) (x^1/3)=2
(2) x^2=64

You can't have the square root of a negative number. Irrational numbers are way beyond the scope of GMAT. If a question ask for $$\sqrt{x}$$ you can assume x is positive or zero.
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18 May 2018, 18:45
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I agree. And I am considering x to be positive (8). However the question asks for sqrt of x. It doesn't suggest that sqrt of x is positive. hence it can be +- 2(2)^1/2. Am I missing something?
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Re: If x is positive, what is the value of x^(1/2)?  [#permalink]

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18 May 2018, 18:46
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vhsneha wrote:
If x is positive, what is the value of sqrt x

(1) (x^1/3)=2
(2) x^2=64

In GMAT, we only consider the +ve root value of a square root. Example: x= $$\sqrt{4}$$ -> x=2, whereas $$x^2$$ = 4 -> x =+2 0r -2.

Now coming to the question, as we are asked about $$\sqrt{x}$$.

St1: $$x^\frac{1}{3}$$=2 -> x=$$2^3$$ so, $$\sqrt{x}$$ = $$\sqrt{2^3}$$. We can definitely get the value of x. Sufficient.

St2: $$x^2$$=64 -> x=+8 0r -8. Note: We cannot have square root of a -ve number so, $$\sqrt{x}$$ = $$\sqrt{8}$$. We can definitely get the value of x. Sufficient.

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Re: If x is positive, what is the value of x^(1/2)?  [#permalink]

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18 May 2018, 18:52
When the GMAT gives you a square root symbol, it’s referring to one specific value: the positive square root.

So from statement 1: x=2^3=8. Sufficient.
Statement 2: x^2=64
IxI=8; x can be +8 or,-8.
As per question stem x is positive. So only x=8 satisfied.
Hence sufficient

Ans: D

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Re: If x is positive, what is the value of x^(1/2)?  [#permalink]

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19 May 2018, 00:05
vhsneha wrote:
If x is positive, what is the value of $$\sqrt{x}$$

(1) $$\sqrt[3]{x}=2$$

(2) x^2=64

Comment: The official answer is D. However, since the question stem doesn't state anything about the sign of x^1/2 (only that x is positive), i am not convinced that there is a unique answer since x^1/2 can be +- 2 {(2)^1/2}

PS: I tried using the math formula buttons. Didnt work for me. Apologize for the format

If x is positive, what is the value of $$\sqrt{x}$$?

(1) $$\sqrt[3]{x}=2$$ --> take to the third power: x = 8 --> $$\sqrt{x}=\sqrt{8}$$. Sufficient.

(2) x^2=64 --> x = 8 or x = -8. Since we are told that x is positive, then x = 8 and $$\sqrt{x}=\sqrt{8}$$. Sufficient.

vhsneha wrote:
Comment: The official answer is D. However, since the question stem doesn't state anything about the sign of x^1/2 (only that x is positive), i am not convinced that there is a unique answer since x^1/2 can be +- 2 {(2)^1/2}

PS: I tried using the math formula buttons. Didnt work for me. Apologize for the format

First of all, we are told that x is positive, so x cannot be $$-2\sqrt{2}$$. Next, the square root cannot give a negative result, that is $$\sqrt{4}=2$$ NOT +2 and -2. (In contrast the equation x^2 = 4 has TWO solutions x = 2 and x = -2).

arosman wrote:
You can't have the square root of a negative number. Irrational numbers are way beyond the scope of GMAT. If a question ask for $$\sqrt{x}$$ you can assume x is positive or zero.

Yes, even roots from negative numbers are not defined for the GMAT ($$\sqrt[even]{negative}$$ is undefined). So, you don't need complex numbers for the GMAT.

GMAT deals with only real numbers: integers (-3, -2, -1, 0, 1, 2, 3, ...), fractions/decimals (3/2, 4/3, 0.7, 17.5, ...) and irrational numbers ($$\sqrt{3}$$, $$\sqrt{2}$$, $$\pi$$, ...).

Check for more below:

2. Properties of Integers

For other subjects:
ALL YOU NEED FOR QUANT ! ! !
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## Linear Algebra and Its Applications, Exercise 3.3.15

Exercise 3.3.15. Suppose $P$ is a projection matrix that projects vectors onto a line in the $x$$y$ plane. Describe the effect of the reflection matrix $H = I-2P$ geometrically. Why does $H^2 = I$? (Give both a geometric and algebraic explanation.)

Answer: When applied to a vector $v$ the matrix $H$ produces $Hv = (I-2P)v = v - 2Pv$. This can be thought of combining the following operations:

First, project $v$ onto the line in the $x$$y$ plane ($Pv$). Next, scale the resulting vector by a factor of 2 and reverse its direction ($-2Pv$). The resulting vector is still on the line onto which $P$ projects. Finally, find the difference between the resulting vector and the original vector $v$ ($v - 2Pv$). The final vector $Hv$ and the original vector $v$ are symmetric with respect to a line that is perpendicular to the original line onto which $P$ projects.

For a simple example, in $\mathbb{R}^2$ consider the projection matrix

$P = \begin{bmatrix} 1&0 \\ 0&0 \end{bmatrix}$

that projects all vectors onto the $x$ axis.

We then have

$H = I -2P = \begin{bmatrix} 1&0 \\ 0&1 \end{bmatrix} - 2 \cdot \begin{bmatrix} 1&0 \\ 0&0 \end{bmatrix}$

$= \begin{bmatrix} 1&0 \\ 0&1 \end{bmatrix} - \begin{bmatrix} 2&0 \\ 0&0 \end{bmatrix} = \begin{bmatrix} -1&0 \\ 0&1 \end{bmatrix}$

When $H$ is applied to the vector $(2, 3)$ this produces the vector $(-2, 3)$:

$\begin{bmatrix} -1&0 \\ 0&1 \end{bmatrix} \begin{bmatrix} 2 \\ 3 \end{bmatrix} = \begin{bmatrix} -2 \\ 3 \end{bmatrix}$

In other words, $(2, 3)$ is reflected about the $y$ axis, which is perpendicular to the $x$ axis onto which $P$ projects.

If $H = I - 2P$ is applied again then it would reflect the vector $(-2, 3)$ back across the $y$ axis to produce the original vector $(2, 3)$. This is true in general for any $H = I-2P$:

$H^2 = (I-2P)(I-2P) = I^2 - 2IP - 2PI + 4P^2$

$= I - 2P -2P + 4P = I$

NOTE: This continues a series of posts containing worked out exercises from the (out of print) book Linear Algebra and Its Applications, Third Edition by Gilbert Strang.

If you find these posts useful I encourage you to also check out the more current Linear Algebra and Its Applications, Fourth Edition, Dr Strang’s introductory textbook Introduction to Linear Algebra, Fifth Edition and the accompanying free online course, and Dr Strang’s other books.

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text:
# How do you factor a^6 + 1?

Apr 14, 2015

We can modify the expression to use the Sum of Cubes formula to factorise it.

${a}^{6} + 1 = {\left({a}^{2}\right)}^{3} + {1}^{3}$

The formula says :color(blue)(x^3 + y^3 = (x + y)(x^2-xy+y^2)

Here, $x$ is ${a}^{2}$ and $y$ is $1$

${\left({a}^{2}\right)}^{3} + {1}^{3} = \left({a}^{2} + 1\right) \left\{{\left({a}^{2}\right)}^{2} - \left({a}^{2} \cdot 1\right) + {1}^{2}\right\}$

color(green)(= (a^2+1)(a^4 - a^2+1)

As none of the factors can be factorised further, this becomes the Factorised form of ${a}^{6} + 1$


text:
# How do you solve frac { m } { 16.1} = 3.5?

Jul 31, 2017

$m = 56.35$

#### Explanation:

$\frac{m}{16.1} = 3.5$

$\iff$ multiply both sides by $16.1$

$m = \left(16.1\right) \left(3.5\right)$

$\iff$ Since $16.1 = 16 + .1$, we can distribute about the sum

$m = 16.1 \left(3.5\right) = 16 \left(3.5\right) + .1 \left(3.5\right)$

And since $.1 \left(3.5\right) = .35$ and $3.5 = 3 + .5$ we can distribute $16$

$= 16 \left(3 + 0.5\right) + .35$

Since $3 \times 16 = 48$ and $.5 \times 16 = 8$ we can say

$= 48 + 8 + .35 = 56 + .35 = \underline{56.35}$