This perspective article covers several functions of Orexin, a lesser known neurotransmitter:
Arousal and sleep/wake transitions
Reward seeking
Stress
Homeostatic regulation
Cognition: attention, learning and memory
and concludes:
http://www.nature.com/neuro/journal/v17/n10/abs/nn.3810.html
There are various kinds of approximation methods in band theory. In my opinion, Bloch theorem implies the existence of energy band. From nearly-free electron approximation or tight binding method, we can calculate the energy band. They can tell us the information of band gap and band width...
On page 56 (see attachment) Dummit and Foote define the notation Z_n as follows:
"Notation: For each n \in \mathbb{Z}^+ , let Z_n be the cyclic group of order n (written multiplicatively). " (my emphasis)
But this notation is surely a bit counter-intuitive since Z_n is an additive...
Hello, this is my first topic here.
I'm studying mathematics, this is my 2nd year and I have a problem about studying. In my life, I studied exams just before some days and I know that I should start to study regularly.
These days, I am spending my time with comp. games or surfing on the...
An eigenvector is defined as a non-zero vector 'v' such that A.v = λ.v
I don't understand the motive behind this. We are trying to find a vector that when multiplied by a given square matrix preserves the direction of the vector.
Shouldn't the motive be the opposite i.e. finding the matrix...
For another thread https://www.physicsforums.com/showthread.php?p=4420542 , I want to give simple motivations for the definition of two groups being isomorphic and related topics. My explanations have become so lengthy that I decided to post them here in 3 parts. ( They are probably too...
Hi,
I am using Hartle to study GR and at one point, there is a leap that I don't understand. He finds the result for the geodesic deviation equation and introduces the Riemann curvature tensor.
Then, we are told that there is an object called the Ricci curvature tensor which is a...
If I have w(x, y, z) and take "dw = (∂w/∂x)dx + (∂w/∂y)dy + (∂w/∂z)dz"; doesn't that accurately describe how w changes as x, y and z change by an infinitesimal? Or does that only work for some special cases?
I feel like if I take the total derivative I am actually describing how the function w...
Hello folks,
I'm a postdoc in CS/Statistics in a small EU country, working in academia as a scientist, no teaching just research. The stupid thing is that our department is the second worst in the (otherwise prestigious) institute, as there are many lazy people around, just procrastinating...
In Dirac's "The Principles of Quantum Mechanics", in chapter V on the equations of motion Dirac proceeds with a line of reasoning that is something along the following lines (I've modified it a bit to coincide with what's taught in the course I'm taking)
1. We assume that the motion...
Hi everyone, I'm currently learning about finite-element methods and I'm having trouble understanding the motivation for the Galkerkin method. Most textbooks I've managed to find are either overly simple or more advanced than my current understanding.
I understand unless you happen to select...
I don't know why, but I just can't get into E&M. I didn't find it interesting as an undergrad, and it's not interesting to me now as a grad student. However, I need to know the material--gotta pass the quals!--and I even want to know the material ('cause it's an important part of physics and I...
Hi everyone.
I have a degree in ME and now I am doing my post graduation in Mechanical Engineering Design. I had a lot of interest in Design during my Bachelors but suddenly I've lost interest in technical field/studies. My GPA is also going down day by day and I find no motive for studying. I...
Hi all,
It is the first time to post in your forum.
While applying for post grad studies, some colleges require a motivation letter while others require a statement of purpose.
so, are the letter and the statement the same?
Thanks,
Where's the motivation for concluding that there are infinitely many unique infinite cardinal numbers?
I understand the proof for it and accept it, but what other useful implications of this can be drawn in mathematics? It almost seems like Cantor developed this idea in set theory just to say...
I've always liked mathematics, and I've always preferred to study mathematics over any other discipline. But now that I'm studying at a more advanced level, it's kind of hard to keep the motivation to study it.
For you who study mathematics, what's your motivation for studying it(other than...
When I look for it, the best I can come up with are things related to making calculations simpler. But I would like something deeper. The best thing I could find is this:
In the (translated) words of Jacques Hadamard: "the shortest path between two truths in the real domain passes through the...
Hi guys,
This isn't a homework question but it's course related. In my mathematical methods in Physics course we were introduced the Jordan normal form of a matrix.
I didn't grasp all. What I understood is that when a matrix isn't diagonalizable, it's still possible (only sometimes...
This is being discussed in micromass's "Math stuff that hasn't been proven" thread, but I want to be particular about this topic.
Essentially, I think I'm looking for a "proof" or derivation of pi from few first principles. Honestly I have no idea which is the "purest", most motivating question...
The book I use for linear algebra explains that the motivation for defining a vector space has to do with the Gauss' reduction method taking linear combinations of the rows, but I don't understand the explanation very well. Can somebody explain?
My mother had a dream that there should at least be one child who goes into the field of medicine and comes out as a doctor. She always used to motivate me to excel in studies be it any subject, mathematics, sciences, geography etc. But as time passed my interest developed more towards the...
I've just realized I don't understand something pretty fundamental about the need to renormalize. Popular wisdom has it (or had it - forget the shift towards an effective framework) that theories that were not renormalizable had no predictive power, on account of the fact each n-point vertex...
I have a quick question. First let me give a definition.
Let a_1, a_2, ..., a_k be independent vectors in R^n. We define the k-dimensional parallelopiped \mathbb{P}(a_1, ..., a_k) to be the set of all x in R^n such that x = c_1a_1 + \cdots + c_k a_k for scalars c_i such that 0 <= c_i...
I'm curious why people develop these objects. Although I've seen some proofs of theorems using coset(or quotient space somtimes), it remains mysterious to me how people come up with these in the first palce. So what's the motivation for inventing coset or quotient space, logical and historical?
I have just finished my first year in Physics, and in a few months I will start the second year, and although I have a lot to study I feel I am stuck when I get to solving problems. Its not like I can't solve them, but I simply want to do something else entirely when I get to the problems...
So I've nearly finished school and, depending on my grades, may go to university.There's probably about 40 people out of 200 who are aiming for university.
Our school runs something called the 'Grammar Stream" and "Alpha Stream". Both these programmes allowed for 'talented students' to have...
Since I began studying at the univ. I find it really hard to motivate myself to study. I always end up thinking "I've got much time left until the exam, I'll study later" and then I always end up studying everything in a rush before the exams. It happened on every single exam/test I've taken, I...
Hi,
Today I was sitting in the train and I wondered what the motivation for a time traveler would be if he wanted to go in the past. Say that I live in 2011 and I went back 210 million years ago to see the dinosaurs, that would be my motivation. But when I would travel back to there and...
Homework Statement
Using the eigenstates of x_op, show that the probability of finding a system described by a wavefunction Psi(x) at a position between a and a+da is given by lY(a)l^2da. Comment on a connection to initial motivation for a wave function from 2-slit interference pattern...
Hi, this has been bugging me for a long time: I am lacking a philosophical concept or just a general motivation behind the concept of an integral. To me, "computing the area under a graph" seems too specialized to me, especially how our pictorial representation of a function could have been...
So I know what they are and I've been given some really vague and weak interpretations, but I want to build up my intuition and know more about the specifics of curl and divergence. To my understanding now I know that
curl is similar to a paddle wheel spinning in a direction dependent on the...
It seems like most people have motivation while they're going to school, but after a forum search, it seemed like these motivations aren't explicitly stated often enough for me to find them. (That, or I stink at using the forum search.)
So, long story short, I'm 31 and have my Associates...
I majored in physics and astronomy as an undergrad, and my interest has been monotonically waning ever since. As a college freshman I was very motivated, focused, and over-achieving; in high school I spent my summers reading about these subjects. Throughout college I worked enthusiastically on...
What is the motivation behind random variables in probability theory?
The definition is easy to understand. Given a probability space (Ω, μ), a random variable on that space is an integrable function X:Ω→R. So essentially, it allows you to work in the concrete representation R instead of the...
Hi PF,
I'm actually still an undergrad, so this is a long ways off, but I've been thinking about what possible route I want to take if/when I complete a Physics PhD program. I've come up with a couple reasons why the quant/finance path (or its analogue in 5-10 years) seems interesting to me...
In the gulf oil spill thread, a few weeks ago, Ivan said something to the effect of: if there's a silver lining to be had in the gulf oil disaster, it's the possibility that it could give rise to a new generation of environmentalists. It got me thinking about how activism is motivated.
I...
| --- willpower --- \\\\\\\\\\\\\\\\
| ------ motivation ------- \\\\\\\\
| ------------ emotion ----------- \
Let's imagine the picture above is a house with 3 floors. First is emotion, second motivation and third willpower. The house has a roof and basement too, which are empty. The...
Well basically the dilemma is I am very interested in maths, I think of math questions as provocative and the sense of genius when you get a complex problem correct. The problem is I am trying to self study calculus II using Stewart's calculus ( single variables) yet i find myself always...
I usually have no shortage of motivation because I like to think about all the practical applications that I could use this theory for in my future endeavours and also how the theory I'm learning expands on and fills in the gaps of what I already know. In maths I can't automatically think of...
If anyone needs motivation to keep an active life, or work shoulder to shoulder with his/her children to prevent them from ending as adolescent fat slobs, here is something to think about:
story of a 11 year double amputee excelling at wrestling...
I am after some advice about confronting some personal demons of mine. I have been suffering depression since I started university, basically 9 years now. At high school I was a straight A student, I understood things easily and liked to learn ... and be challenged though I wasn't very often...
Now I am reading on Technicolor. Unfotunately I am not clear yet what is the exact motivation of Technicolor? Please help me to clarify this. Thanks in advance.
I keep seeing this word a lot. In reviews of textbooks (apparently some authors provide more motivation), in the textbooks themselves (one of mine said that no proof of the cauchy-schwartz inequality is well-motivated) but despite lots of google searching I can't really get a clear definition of...
What is your purpose in field of Computer Science ? Do you have any idealistic aims ? As we know it is the one of the leading fields of world in next years, what kind of targets can be constructed to increase your motivation level to work hard ?
I attend a rather small university in Canada. I'm doing my MSc. in physics and I've noticed that myself and other grad students rarely have any motivation to do their grad work. Personally, I'm at the pre-experiment stage where all I'm doing is reading papers about the subject, which I find to...
Say a week, month, or year of undergoing consistent tasks, during this time, every morning when you wake up you kind of forget who you are. You start to hate everything about your hobby/career path. If it's a hobby, you simply quit. For an education, it's not that simple... but if you quit...