I just graduated in aeronautical engineering (master of science) at the Polytechnic of Milan. In the Italian university system, students who finish their major get a final grade that that goes from 66 to 110 (plus honors). In my particular case, I got a 103/110.
Since I am writing my resume/CV in English, I would like to convert my Italian final grade to the American (GPA?) and U.K system.
Can anyone suggest me what conversion I should follow?
I had the impression that obtaining written permission before including someone in acknowledgements was required. Therefore, I just wrote to someone asking for written permission to include him in the acknowledgements of a paper, and he said he didn't think it was necessary. I don't recall where I got this notion from - perhaps the rules of a specific journal? So, I was wondering if there are any general rules about this or not, or are they perhaps journal specific?
If I were to do a blue/white selection of transformed E. coli on LB agar ampicillin plates at room temperature (23⁰C) for about 2 days and 18 hours, will I run into the issue of satellite colonies or any other issues?
I recently completed a part of my project and communicated a paper to a conference. Let's call the paper's title as "project x: for this and that". Now, I wish to open-source project x to facilitate reproducible research and to have more (at least some) people use it (and cite it!).
Are there any specific drawbacks or risks involved in open-sourcing project x on, say, Github or Sourceforge? Do note here that I would still be improving on project x, and possibly sending the extended version to a journal (my area of work being Computer Science).
I understand that if a conference/journal requires double-blind review and my project is searchable on the Internet, I am revealing my identity to the reviewers. This is bad, right?
Are there any other cons I should be considering? And are there any pros of open-sourcing before a making it into a publication?
Answer
Double-blind reviews are usually more common in conferences. For example, I don't know of any journals using double-blind review in my field (machine learning). I'm going to assume revealing your identity is not an issue (if it is, circumstances differ).
Whenever relevant I provide an implementation along with a paper. This also helps reviewers, in case they want to fiddle with an algorithm under slightly different circumstances than those reported in the paper (which is a good thing!). When an implementation is provided, the option is there.
The pros are increased visibility, reproducibility and (in my opinion) credibility since you allow everyone to try for themselves instead of taking your word for it in the paper. On rare occasions, your software may become quite popular during the review period, which may positively impact the paper under review.
A potential con is that someone may discover a critical bug in your implementation. From the perspective of software engineering this is always helpful since you can then improve the software. For the associated paper this may be a good, bad or irrelevant thing, depending on the type of bug:
A similar question but about teeth healing themselves is Do teeth have the capacity to heal?.
So I understand that teeth have the capacity to heal themselves to a certain degree. It appears to be that part of the reason they can't heal all of themselves is that they are not surrounded by cells. In that case why can't we grow teeth back?
If a tooth is grown in the gum, or somewhere else, it would be surrounded by cells and so should be able to grow back right?
It appears that sharks can grow their teeth back:
New teeth are continually grown in a groove in the shark’s mouth and the skin acts as a “conveyor belt” to move the teeth forward into new positions.
Why can't we do this?
Answer
Unfortunately, the answer to your question isn't as well researched as other areas, I believe...let's add some complexity into this.
You're correct, teeth does "grow" in the gums. And it does start off surrounded by cells (look up: tooth bud, cap, bell stage)!
The tooth originates from an interaction between the ectomesenchyme (likely originating from the neural crest cells) and the epithelium of the mouth when it is forming while you're still an embryo in your momma's tummy.
Unlike sharks, which are homodonts (meaning, their tooth are all of one morphology), we are heterodonts (e.g. we have different shaped teeth - e.g. molars, canines, incisors, premolars). There are a couple of theories to why this occurs (look up: clone model, field model, odontogenic homeobox code - a combination of all these theories). Basically, a bunch of genes transcribe for proteins and signalling factors that create the complexity of your tooth shape and position in the mouth.
Basically, this means, our teeth are going to take longer and require more energy and effort to carve into (yes carve! lot's of the tooth shape is create by apoptosis of the regions around the "cusp" area when it is developing).
When your primary/baby teeth pop out, they serve functions such as developing speech, allowing you to eat, strengthening your jaw muscles (which in turn helps to develop your mandible and shape of the face), all this so you can have a great bite when you get older!
Luckily, sharks don't speak much underwater, so they probably don't give a poop about having properly lined up teeth. Their teeth grows everywhere. Proper bite for eating various nuts, fruits, meats and vegetables? NAH. WE JUST CHEW OFF LEGS. WE CAN ONLY SHRED STUFF. Sharks need strong ankylosed teeth (ankylosed = like an anchor? teeth are anchored into the mandible of the shark).
In contrast, humans have teeth in gomphosis (sockets), which gives our teeth some cushioning and sense of proprioception (the sense knowing how hard you're biting) when we bite on something extremely hard, to prevent us breaking our teeth - thus helping us preserve our teeth. Sharks don't have that, they just break their teeth.
Humans do finally replace their teeth, after our jaw grows enough for us to accommodate them at a genetically planned stage. This happens by tooth germs (cells) being bud off (like a flower yes :D) from the baby teeth. Note though, your 1st adult/permanent molars are already beginning to form when you're still in your momma's tummy.
I believe that the continuous creation of teeth requires more energy, but takes less time (sharks). For humans, one time creation of teeth requires less energy, but takes wayyyyy more time (and also has to be timed correctly with all our other growing bits).
TL;DR Evolutionary reasons and different functional uses of teeth between sharks and humans probably determine why we only have two sets of teeth (diphyodonts). That being said, it would be cool if we were like rats (have molars/incisors) though, which replace their teeth anytime its lost. Maybe one day we can evolve into it? Yay!
Some interesting points: You mentioned teeth "healing".
Your teeth is made up of enamel on the outside, which is NEVER replaced. It "heals" by remineralisation which is not exactly the same as growing new crystals on top of it. Kinda complex, won't go into it.
However, your teeth is always forming new dentine, which is below the enamel. In a way, your tooth really is growing back all the time. Because a new layer of dentine is deposited everyday (like...4 micrometers). This is because the dentine producing cells, called odontoblasts, are still around. In contrast, the enamel producing cells, called ameloblasts, are removed when your tooth has developed. I THINK, the reason is to make space in your enamel so it can be fully mineralised and completely filled up by hydroxyapatite. (Too much fluoride when young can block this removal of ameloblasts and its proteins like amelogenin and enamelin = forming holes, which cavitate resulting in fluorosis).
Hopefully all that answered your question. But, it was fun for me to rant anyway. Cheers.
I'm surprised to see that an academic who died over 50 years ago has a Google Scholar profile with a verified email (https://scholar.google.com/citations?hl=en&user=5qvdHjQAAAAJ):
How is that possible? I see the email domain, melipona.org, is some online shop.
Answer
Verified email just mean that the user has done the confirmation in his/her inbox. It means in that case that the person that created this profile has an email with the domain "@melipona.org".
Usually, people will do this verification with their institutional email, adding credence that this is the right person, but technically, anyone within an institution can do it for anyone else inside that particular institution.
My research group has regular group meeting but I usually think it is not effective. In particular the research area of the group is very diverse, every time I just listen on something I cannot understand and have totally no interest on it, and I believe other members think the same way as I do when I am presenting. While it is a good way to expose to something new, and know other group members what they are doing, this is not effective for my own research. I know group meeting has its point (What is the purpose of the weekly research meetings that advisers often have with their research group?), but how can it be conducted in a more effective way?
As a supervisor:
As a student:
If you are a faculty, how do you conduct your group meeting? As a research student, what can you suggest for an effective group meeting? An effective group meeting can greatly help on one's research work, otherwise it is just a drain of energy, time and motivation.
Answer
You have a lot of questions interspersed within your question, but it sounds like the main issue is
the research area of the group is very diverse, every time I just listen on something I cannot understand and have totally no interest on it, and I believe other members think the same way as I do when I am presenting.
I have had the same problem in the past. I'm a professor who works in a variety of related subfields, some very theoretical and some fairly applied. Most of my students and postdocs have been focused exclusively on either something theoretical or something applied, and their backgrounds range from computer science to mathematics to electrical engineering, so there is often a disconnect when they try to communicate what they are doing. Here is my advice.
Use meetings for skills development. This was already mentioned in this related answer. Instead of focusing exclusively on research, group meetings can also include discussions of things like:
These topics are useful and interesting to anyone involved in research.
My dad asked this question when I explained some circumstances surrounding Homo sapiens survival against all odds.
We know there is only one hominid species left in the world, Homo sapiens. We also know that there are only 6 other species of great apes left: 2 species of chimpanzees, 2 species of gorillas, and 2 species of orangutans. These 7 species are the last remaining in the family Hominidae.
All the other hominids besides Homo sapiens died out tens of thousands of years ago, and we believe the reason our ancestors survived is because we were more "adaptable", meaning we were not restricted to a single environment but could survive in many others. This is the reason we later spread out all over the world, and probably why we gained "sapience" and are able to contemplate these grim circumstances.
At one point, following the eruption of the Toba volcano 70,000 years ago, there were between 1,000 and 10,000 mating pairs of Homo sapiens left, though there may have been other hominid species alive at the time. My dad asked, if the hominids faced such grueling environments and all but a few died, why did the great apes fare any better? Why are there 6 extant non-human Hominidae species left, but only 1 hominid species?
Answer
Determining why one species (or group of species survived) while others did not can be difficult to answer, but I can offer one possible explanation for the genus Homo: competition. Competition between similar species is one possibility. Consider for example gorillas or chimps. The two species of gorillas occupy different habitats so they rarely compete with each other for resources (food, water, shelter, etc.). The two species of chimpanzees have non-overlapping ranges (or minimally so) so again they do not compete for resources.
Chimps and gorillas do overlap with each other for parts of their range and even potentially use the same resources, although no competition for resources has been observed (see this primate factsheet and McNeilage 2001). The same applies for the orangutans, which lives on two different southeast Asian islands.
The genus Homo is an entirely different story. As you may know, Homo first evolved in east central Africa. The first species to leave Africa and disperse across Europe and Asia was Homo erectus. This migration out of Africa happened as early as aout 1.8 million years ago. Homo sapiens had not yet evolved. However, while H. erectus was establishing itself across Europe and Asia, populations still in Africa continued to evolve.
Modern Homo sapiens evolved in central Africa perhaps about 250-200,000 years ago and dispersed out of Africa about 100,000 years ago. Homo sapiens also dispersed across Europe and Asia. Both H. erectus and H. sapiens co-occurred across parts of their range. Some have argued (Stringer and Andrews, among others, I believe but I'll have to be at work before I can verify ths reference) that H. sapiens outcompeted H. erectus, leading to its eventual extinction by competition. They occurred together and used the same resources, so H. sapiens could have caused the extinction of H. erectus. This has been called the replacement hypothesis. The later evolving species (H. sapiens) replaced the earlier evolving H. erectus.
However, Templeton (2002) has argued that the two species interbred so the species became integrated rather replaced (if I am interpreting him correctly). While I don't dispute the possibility of interbreeding, I am skeptical of Templeton's complete dismissal of replacement.
Complicating the picture is H. neanderthalensis. Genetic evidence published by Green et al. (2010) suggests that Neanderthals diverged from H. sapiens (in central Africa) between 800,000-500,000 years ago and also dispersed out of Africa. They also provided evidence of interbreeding between H. sapiens and H. neanderthalensis in Europe. Modern H. sapiens may also have outcompeted H. neanderthals.
All of this was occurring during the Pleistocene ice age. Europe was experiencing repeated bouts of extensive glaciation. Thus, it is also possible that climate change caused or contributed to the extinction of H. erectus, H. neanderthalensis, or both.
In summary, the processes that led to the extinction of other species of Homo are complex and likey interactive. Competetion among species is, in my view, well within the realm of possibility but would be extremely difficult (if not impossible) to test. Climate change is also a very likely contributing factor. There are several other hypotheses but I have tried to hit the major highlights. The debate is certainly not settled.
McNeilage A. 2001. Diet and habitat use of two mountain gorilla groups in contrasting habitats in the Virungas. In: Robbins MM, Sicotte P, Stewart KJ, editors. Mountain gorillas: three decades of research at Karisoke. Cambridge (England): Cambridge University Press. p 265
According to wikipedia and the original complete sequence of the K-12 genome, there are multiple non-AUG start codons such as GUG and UUG. How is this possible? I'm particularly curious about the mechanism of translation initiation in the absence of the canonical tRNAfMet.
Answer
Actually, the start codon, no matter whether it is AUG or GUG/UGG, always encodes for Met. So the translation is initiated by tRNAfMet (prokaryotic translation). The 30s ribosome subunit binds to the Shine-Dalgarno sequence and then it scans the dowstream mRNA sequence for AUG and the tRNA loaded with Met, which has the CAU anticodon form the most stable interaction. But apparently, only two-bases-interaction between the start codon (GUG, UUG) and the fMet-tRNA anticodon are sufficient for the initiation of translation (1). I will look more into the literature.
1. Initiation of translation in prokaryotes and eukaryotes
My 8 year old son asked me a question I could not answer (and Google, at least in so far as we tried, was no help either).
We were watching a documentary about Salt Water Crocodiles in Northern Australia.
The crocodiles seem very energy efficient: they barely move if they don't absolutely need to (and when they do, it is mostly to eat). Particularly, they hardly ever run, but when they do they are very fast and powerful.
So the question he asked me was: how can crocodiles remain so fit if they don't do any exercise?
If humans just sat around and moved only to eat, ran only when they absolutely had to, our muscles would atrophy. Other mammals seem to be in a similar boat to us humans.
Why not crocs? What distinguishes animals that need to exercise to be strong from animals that don't?
This is the closest question I could find here, but I don't think it assists in answering this question: Do insects' muscles become stronger with exercise?
Answer
Let us start with difference between humans and crocodiles. There are lot of differences but the one which matters in current discussion is thermophysiology.
Unlike humans, crocodiles are cold blooded animals (more specifically ectotherms). These animals needs to get heat from environmental sources to maintain their body temperature. As contrast to humans who can get heat from internal metabolism. That is the precise reason crocodiles are seen always not moving and basking in sun light when it is cold (while go to shade or water if it is hot). Read this for more elaborate strategies they use. If you want scientific reference, you can check this, this or this.
On your exercise point, there are few reports which suggest exercise can enhances aerobic capacity in young crocodiles. In this study they actually put crocodiles on treadmill and checked affect on their respiration. This report suggest crocodile uses 3 different kinds of muscle mechanisms for lung ventilation. These three act differently in different conditions (means one acts during rest while other during high metabolism). However I couldn't find any information regarding atrophy.
how can crocodiles remain so fit if they don't do any exercise? What distinguishes animals that need to exercise to be strong from animals that don't?
Short answer: Their body metabolism.
Their body metabolism is different from human's. Although doing exercise might help in their aerobic capacity as mentioned in reference above.
Should one create slides similar to those that one uses in a good powerpoint presentation? Or are there things that a poster should include that a powerpoint should not include? (and vice versa)
Answer
The title is your bait, the first paragraph is your hook. Make the bait big and tasty, make the first paragraph catchy.
A poster is primarily an advert for you. Secondarily, it's an advert for your research. Thirdly, it's an advert for your department. And it will succeed at those things best, if it gives the casual reader an easily accessible introduction into what's novel about your research.
Know the flow: it should be clear to anyone reading, what they should read first, then second, and so on.
Make it clear that it's your work. Get your name and affiliation in big letters, with a photo of you. Include your contact details, and make sure you can be reached on them during the conference.
Don't use powerpoint. A poster is graphic design, so use a graphic design package such as InDesign. If you don't have an eye for graphic design, design the poster with someone who does. Most departments have at least one natural talent. It's often the person who keeps winning the "best poster at conference" prize. It's orthogonal to (i.e. independent of) quality of research.
Use a big, clear typeface. Not everyone you need to reach has the healthy, clear vision that most students have.
Briefly state the problem, the method, the results, and the implications.
Pretty pictures are crucial. The words are there just to supplement the explanation of your work given in the pictures.
Test, test, test. Print it out life-size (tiled sheets & sticky tape are your friend), show it to a couple of colleagues (one hot on your area of research, and one hot on design), watch the order in which they read things, ask for feedback. Implement any advice on content that comes from the one who is hot in your area of work. Implement any advice on design that comes from the one hot on design.
My university uses TurnItIn to check student's work for plagiarism and collusion. I think the underlying TurnItIn database includes both submitted work and material it has found by crawling the web, but not material behind pay walls. One major issue with TurnItIn, and presumably all plagiarism detection software, is that it can only compare submitted work to material which is in the database. This means that TurnItIn either misses when students copy from textbooks which are behind a pay wall or matches other sources which have plagiarised the textbook.
My department's academic misconduct committee is thinking about seeding the TurnItIn database with the textbook chapters that are most often used by the students by submitting a number of "assignments" that are copies of the textbook chapters. This would require an individual member(s) of staff to submit assignments that contained copied copyright material. Is it possible that this could get the staff member in trouble in the future? We were thinking about adding something like:
The following submission is intended to seed the TurnItIn database and is an exact copy of FULL REFERENCE.
Would this work, or would TurnItIn realize that it is being given copyrighted material and purge it from its database?
Answer
This is a bit long for a comment, but I also acknowledge that only someone from TurnItIn could categorically answer this.
Since TurnItIn does not provide access to source material (other than small sections which actually match the submitted paper), I do not see how it could be a copyright issue. I get matches all the time from papers submitted to other schools, yet, TurnItIn does not allow me to see that paper.
Additionally, much of the content within TurnItIn is under copyright (blogs and others) and they do not purge it, further implying that they would not have a problem with your plan.
All that said, unless the content is quite new, or changed regularly, as soon as one student includes content, any other student including that same content will trigger a flag for you.
So, I do not believe your plan will have any problem but I am also not sure you need to worry about it unless you have a special set of texts you believe other students around the world will not have access to.
I'm taking a machine learning class at a school in South Korea. I've heard some good and bad things about this professor in particular, but I didn't really know until I actually took his course.
I've noticed that my instructor is literally following the exact course of the well-known online machine learning course taught by Coursera co-founder Andrew Ng. The print-outs he uses in class are also taken from the online course, and the examples and jokes he uses are also the same to the T. There are other print-outs he takes from Youtube which I happened to find which he seems reluctant to address when I asked him about it.
Perhaps I am thinking/acting out of my place, but I just don't think that it's appropriate, and maybe I feel a bit cheated because many students (including myself) have to work several jobs to come up with tuition money, and it doesn't feel good that I'm paying a large amount of money for a potentially free online course.
How should I feel about this? Is this more commonplace than I feel?
EDIT
I haven't mentioned the quality of education I'm getting through the course.
The quality is low, which is what led to my initial frustration. I honestly couldn't care less what material instructors are using as long as they cite the source and are able to use it to everyone's benefit. This instructor is not only not citing the sources, but is reluctant to tell me where he got them when asked about it.
Regarding the class itself, I've found myself in situations where asking the instructor of this particular class a question is often either not answered in a clear manner or is answered with "Just email the TA's," which has led me to seek answers either online or elsewhere.
Perhaps this is my prejudice, but when I ask a professor from an internationally accredited institute of higher education a question on machine learning, I am hoping to get a detailed explanation on the mathematical or conceptual reasons to how certain algorithms were formed or how we can prove they are sound. Not just an answer that goes along the lines of "Hmm well when I was working on this project this algorithm worked best, and you can find the proof online."
Answer
Copying an entire course from Coursera is definitely not commonplace. Some parts of ML courses are fairly 'standard' (there are only so many ways one could define linear regression), but lifting material without proper credit can range from annoying, unethical to outright plagiarism. It's fine to take some examples and use them (with proper credit), but it's generally expected that an instructor adds some value of their own.
I don't know how you should feel about this. Sounds like you already are feeling pretty annoyed (I would!). I can answer what you can do about this.
The minimum I would do is report this in the student course evaluations. Write a detailed report of everything that went wrong. If you school's administration cares in the least about their teaching, this will get someone's attention.
The best thing you can do is rally the entire class. If it's just you - well, you're just an angry student who's not getting the material and is trying to squeeze a good grade. If a significant number of complaints come in (even 10 students is a good amount), that's going to get people's attention. Does your university have a student union? An ombudsman? If you go through them this will also get people's attention.
You can also try to (discreetly) reach out to the person in charge (professor in charge of curriculum, the department head etc.). I would not confront the lecturer directly if I were you, unless you don't mind getting a bad grade. It is very unlikely that this instructor will be removed from the class, and if they find out you reported them they may be very biased against you: reporting paints a target on your back (this is another reason to have more people complain, the instructor can't fail all of them and get away with it!).
The likeliest outcomes here are that the professor will not be teaching this class in the future, and that's about it. Alternatively, they'll be required to stop this bad practice in future iterations of the class (say, if your department is understaffed). I don't foresee them facing disciplinary action, unless this is not the first time that this has happened.
Good luck!
Many researchers list out their submitted manuscripts on their website. Some specify the journal name, like
Smith J, Oliver J (under review) My awesome paper. Nature.
while others don't, like
Smith J, Oliver J (under review) My awesome paper.
One reason I can think of as to why some don't mention the journal name is that they may get embarrassed in the case where the current journal rejects the paper. Then, the "circle" will know this paper gets rejected from Nature first and then ends up in an inferior journal.
Besides this, are there any other considerations preventing people from mentioning to which journal they submit a paper to?
P.S.: I am asking because my advisor is a researcher who only mentions accepted papers on his webpage. As a student hunting jobs, I feel it is advantageous for me to mention my submitted papers on my webpage. I hesitate to do so, as I worry I may make my advisor unhappy by announcing in which journal our papers are currently under review.
Recently I found a paper that has a number of typographical errors, esp in equations. Should one notify the authors or the publishers on such issues? How do the approach change if the article is somewhat aged?
When should/can one write a 'Comments on ...' article? How different is an Errata and a 'Comments on ...' article?
Answer
Here's what I would suggest:
Errata are “authored” by the original authors. Publisher's corrections also exist, when the responsibility for the issue (typo in equation, misprint in figures, etc.) is that of the publisher.
I'm applying to MS / MS-PhD programs in CS this fall.
I don't have a good GPA (2.86 on a scale of 4). I have experience as a research assistant under a professor and also a couple of good projects.
Right now I'm working as a developer, so I have around 5 months of experience. I have a GRE score of 314 on 340. I'm giving subject test to improve my chances of getting into a grad school. What score can be considered 'good'? I don't have much time to prepare and I am a little rusty on some of the topics, what is the good advice for a crash course for subject test in, say a week or so?
I have been in a rush to accomplish academic goals since I remember myself. Started my PhD right after undergrad and did my Masters on the same time. Now I am about to submit my thesis and feel kind of burned out, having spend so many years in a far from perfect working environment.
Academia has always been my goal (I like both teaching and research and I am not interested in industry), which is why I started a PhD on the first place, but I really feel I need a big break to think clearly of what I really want before applying for a post-doc. I also read this somewhere: "The rest of your life you are going to be a scientist. This could be your last chance to be something else. Take it."
So I thought a "late gap year" would be ideal for me. I would get to travel, which I love, volunteer in wildlife conservation and in schools of developing countries and take some time to clear my mind, so that when I am back, I can take the right decision for a post-doc and be totally dedicated in it.
Up to now I have a decent resume with a 5th paper in preparation (including first-authored) and several international conferences, fellowships and awards. However, I am very concerned on the impact such a gap would have on my CV, since I want to apply in high reputation universities/institutes, where competition is fierce.
Should I tell a future PI I did a gap year and if not, what would be the appropriate excuse for a year off? Also would this gap have an impact in future job-seeking (mainly for positions in academia)? Finally, I am also worried about the reaction of my current PI (who has been asking me lately, which lab I am planning to apply for a PD) when I tell him my plans. The last thing I want is a reference letter from an angry PI.
*EDIT*My field is Molecular Biology. I performed my PhD research at several European countries and I am flexible with post-doc positions (Europe/Israel/US/...) depending on the projects available.
Answer
As usual, if you include information about geographic location (both the current one and the one(s) in which you intend for the future) and your field, you can get more specific advice. Advice which is generalized across all the world's academia is at times extremely superficial.
I will speak from the perspective of American academic mathematics. In this subculture, taking a full year off before starting a postdoc looks bad: the competition for postdocs is extremely fierce right now. For every postdoc position there are at least five other people who wanted that position but couldn't get it. So employers really want to give jobs to people who are sure that they want them, not those who are feeling "kind of burned out" or "need a big break to think clearly of what I really want".
If you take a full year off instead of applying for postdocs, then unless you have something amazing to show for yourself at the end of that time, the year off will definitely hurt your applications. Whether or not you can actually do work during a "year off" seems highly field dependent: in mathematics this is certainly possible; in laboratory science this seems much less feasible.
Here is some advice that I would offer you:
1) If you want to take some length of time off, try to secure a job upon return before you take the time off.
If this happens then in some sense you do not really have an employment gap, and that will look much better on your CV.
2) Consider taking a smaller amount of time off than a year.
A year is a really long time to put aside one's career. In fact many people would have trouble supporting themselves (especially if they have families or dependents, which I guess you do not) over such a long unpaid stretch. It is also more than enough time for your academic skills to atrophy. In some academic fields (pure mathematics not so much, although in some subfields this could still come into play) a year off is enough to make your entire research program less fresh and cutting edge. Anyway, imagine that you are competing with many talented young people who spent the first year after getting their PhD working their butts off. Do you really want to spot them an entire year headstart? As other people remarked in a closely related question: whether it is fair or not, you should imagine that a big clock in the sky starts ticking the second you receive your PhD. From that point on, people will be evaluating your work not just in an absolute sense but relative to the time elapsed from that point. Adding in an extra year makes almost anyone's profile look much less strong.
I think you should consider taking a shorter amount of time off: either a semester or a long summer. As the American academic calendar runs, you will have a built-in vacation of about three months just by virtue of being an unemployed PhD over the summer. I really enjoyed this time: I moved into an apartment downtown in the city where I grew up but hadn't spent more than a few weeks at a time for my entire adult life. It really was refreshing and recharged my batteries. However, it also depleted my savings: by the time the new semester rolled around, I really needed the paychecks.
If you need much more than three months' break from a career, you should ask yourself: are you sure that this career is really for you?
Is there any research/study/survey that looked at the location of predatory publishers? (e.g., x% are based in country A, y% are based in country B, etc.)
I am mostly interested in English-speaking venues and the field of computer science. Trends over time are welcome as well.
I am an assistant professor at an undergraduate college in India. I teach a rigorous compulsory course in microeconomics, requiring some intermediate-advanced math knowledge. There is no add/drop option at my University/college, nor is there an option to take a course in a later semester. I don't decide the syllabus or the final exam--it is set centrally. We are a publicly funded University and have a diverse set of students.
General math preparation in my country is low, due to poor schooling standards and sometimes, students are not clear about basic concepts: for example, in a third semester intermediate microeconomics course, some of them don't know how to write the (linear) equation of a budget frontier (something taught to them in the first semester). Unless they understand such things, it is impossible for them to grasp the rest of the material, since all topics are related. Is it my responsibility to explain concepts taught in introductory-level courses? I welcome all questions and have a generally amicable attitude, so students don't feel intimidated in getting a clarification.
However, I do get frustrated sometimes when having to answer something very basic, that too repeatedly. I get glowing feedback for most of my courses, but despite being appreciated for my effort and the clarity of explanation, a group of students (around 20% of the class) repeatedly under-performs, which upsets me a lot. How much should I hold students responsible for their learning?
I wonder whether it is possible to bulk download all papers stored in Sci-Hub.
I am aware of the questions:
but they focus on arXiv.
Cross-posted question on Open Data (not encouraged by Stack Exchange policy): Bulk download Sci-Hub papers
One of the most important challenges that academics will face is group management. Although this takes many forms for graduate students, undergraduate assistants, and so on, I believe postdocs are a fairly "universal"—a professor hires a postdoc specifically for his group.
However, it's not necessarily clear what qualities to look for in a postdoc.
Does it make a difference if it's your group's first or second postdoc, versus the n'th postdoc?
How much weight should one give to letters of recommendation?
How do you analyze a publication record, especially when towards the end of the PhD, many papers are often still unpublished and therefore "embargoed?"
Are there any criteria that applies specifically to postdocs that might not be considered in, say, hiring for industry or business?
Answer
My answer, item by item:
I'm working with a non-profit organization at the moment and we're planning to conduct a survey on ~93,000 to find certain attitudes and the correlation associated with them. We're hoping on having our results being published in a reputable journal if possible, because we've done a lot of research and background reading to have a pretty solid study design written down. Is it necessary for us to have IRB approval to publish in a reputable Psychology/Educational academic journal? Additionally, even if it's not explicitly stated in the manuscript guidelines, are there "unspoken" rules about stating IRB approval before submission?
Disclaimer: Since this question is explicitly about applying to do a PhD, I figured that the Academia SE was a better fit than Workplace, but do correct me if I'm wrong.
How can I explicitly, concisely and effectively explain a period of frequent job-hopping in my employment record in my application package (e.g. in the cover letter, statement of interests, research proposal and/or in my CV itself) which was due to a period of "soul-searching", after which I realized that I definitely do want to do research? I assume that my problem is two-fold:
Answer
Job hopping is potentially a problem in getting into a PhD program. The fear of admissions, obviously, would be that your lack of commitment to one thing will show up again in your studies, and you will tire of this quickly, too.
However, it may be less of a problem here than in looking for new employment in industry. Some reasons:
What should you do about it?
From what I understand, your body needs certain amounts of vitamins and minerals to maintain health. Why can't we just take enough pills to obtain these vitamins and minerals?
Answer
This is more of a biochemistry question and to be honest its a little bit out of my league because I have not had the necessary grad classes to explain nutrition but indeed I will try.
Unknown metabolite cofactors and things like ionization, oxidation and state of matter are the reason that straight up vitamins are rejected by the body and cause really expensive urine and a difficult time otherwise excreting.
Metabolism involves a vast array of chemical reactions, but most fall under a few basic types of reactions that involve the transfer of functional groups. This common chemistry allows cells to use a small set of metabolic intermediates to carry chemical groups between different reactions. These group-transfer intermediates are the loosely bound organic cofactors, often called coenzymes.
Each class of group-transfer reaction is carried out by a particular cofactor, which is the substrate for a set of enzymes that produce it, and a set of enzymes that consume it. An example of this are the dehydrogenases that use nicotinamide adenine dinucleotide (NAD+) as a cofactor. Here, hundreds of separate types of enzymes remove electrons from their substrates and reduce NAD+ to NADH. This reduced cofactor is then a substrate for any of the reductases in the cell that require electrons to reduce their substrates.
Therefore, these cofactors are continuously recycled as part of metabolism. As an example, the total quantity of ATP in the human body is about 0.1 mole. This ATP is constantly being broken down into ADP, and then converted back into ATP. Thus, at any given time, the total amount of ATP + ADP remains fairly constant. The energy used by human cells requires the hydrolysis of 100 to 150 moles of ATP daily, which is around 50 to 75 kg. In typical situations, humans use up their body weight of ATP over the course of the day. This means that each ATP molecule is recycled 1000 to 1500 times daily.
If you did not like that explanation of cofactors maybe you will this:
Whole foods offer three main benefits over dietary supplements:
Greater nutrition. Whole foods are complex, containing a variety of the micronutrients your body needs — not just one. An orange, for example, provides vitamin C plus some beta carotene, calcium and other nutrients. A vitamin C supplement lacks these other micronutrients.
Essential fiber. Whole foods, such as whole grains, fruits, vegetables and legumes, provide dietary fiber. Most high-fiber foods are also packed with other essential nutrients. Fiber, as part of a healthy diet, can help prevent certain diseases, such as type 2 diabetes and heart disease, and it can also help manage constipation.
Protective substances. Whole foods contain other substances important for good health. Fruits and vegetables, for example, contain naturally occurring substances called phytochemicals, which may help protect you against cancer, heart disease, diabetes and high blood pressure. Many are also good sources of antioxidants — substances that slow down oxidation, a natural process that leads to cell and tissue damage.
Are the photoreceptors in our eyes not fast enough to register the fast moving bullet, or is the brain not powerful enough to make sense of something happening that fast?
Answer
It's less a problem of speed and more of raw photon count. Assuming a brightly lit day, the bullet will move so fast that it doesn't reflect enough photons to register against the background. High speed images of bullets usually involve a very bright flash (and other controlled settings) for the camera to pick it up. (Also, a very short flash helps the bullet to appear stationary in the image.
On the other hand, seeing where your bullets are going is pretty useful. Therefore tracer bullets were created, which are essentially a pyrotechnic flare that you substitute in every 5th bullet, typically in machine gun ammunition. Proof that if you make a bullet bright enough, you can register it just fine.
http://en.wikipedia.org/wiki/Tracer_ammunition
I'm taking a microbial physiology course and we noted that, while some archaea are phototrophic, there are no known photosynethetic archaea. Are there any physiological characteristics that make archaea less suited for photosynthesis? Or is it simply a matter of there likely being photosynthetic archaea, but they have not yet been found (which seems like it could easily be the case, given that there are many extremophilic archaea)?
I once wanted to do a PhD in the UK, but found out that the opportunities were limited for those coming from outside Europe (I did my PhD in Norway instead). I think it is still the case today. I am wondering why this is so.
EDIT:
Additional thought: I am wondering, for instance, if the vacancy were open to anyone in the world, would it not increase the chance of getting the best applicants? Also, what differences are there in the UK system compared to other countries (e.g. Norway) which open their PhD vacancies to anyone?
I'm trying to understand more about inheritance of an autosomal recessive trait that runs in my girlfriend's family. How could I start looking at this?
My girlfriend's sister, C, is affected with a recessive trait. Her parents, A and B, are confirmed unaffected carriers. Am I correct to assume my girlfriend, D, is a carrier with probability 50%? Or must I take into consideration that we know the state of C given she is affected.
Furthermore, if I (E) have a child with my girlfriend, what is the probability that our children are either carriers or affected? My carrier status is unknown.
My son found this floating in a stream in Massachusetts, in the northeastern US. It was intact when he found it, but he cracked it open to see what was inside. I did some Google image searching, but couldn't find anything. Any idea what it is, and where it came from?
I have not been able to locate any research that indicates whether a single axon of a neuron or nerve cell can conduct multiple simultaneous (i.e. spatially separate) action potentials. I am aware that in many neurons refractory periods would preclude this possibility, however in some cases delays along axons are large enough.
Is this the case? Can you point me to any citations supporting your answer?
It recently occurred to me that probably more often than it should happen, while reading someones paper, they see a reference to a different paper, and just use the reference without looking. In my area, a common example is in referencing data, such as average human height, etc.
I came across this as I was looking for data on human dimensions from a somewhat smaller country that does not use English. I found 9 papers that all referenced the same data sheet. I then contacted the author of that data sheet and was informed that there is no online version (never has been), and the only print copy exists in that country. The author herself does not have this book. I'm guessing the only reason the other authors referenced the data was because the author of the referenced data wrote a paper that referenced her own data.
I am not interested in how to format these citations. I would like to know if it is appropriate to cite this information at all, or cite that someone else cited it. I am curious as I am not sure about the accuracy of the information. If I do cite someone else's citation (which i am 99% confident they never saw the data), it seems like I can just make something up myself. Is there a way to express that maybe this data is accurate, but that I'm not sure, since it is the only available source about that data? Or should I ignore it all together and pretend as if there is no data?
Answer
Is there a way to express this (not as a citation format), that maybe this data is accurate, but not sure, since it is the only available source about that data.
How about something like: "X, measured by Jones in 1950, is commonly given as the value for Y (as cited in Smith, 1989 and Cutler, 1995). However, the original manuscript by Jones describing this result is not generally available."
Or should I ignore it all together and pretend as if there is no data.
Don't do this. If X is cited often in the field, then by pretending as if there is no data, you give the appearance of not knowing your field.
Whether or not you should use X (knowing that it is unreliable) depends on your purposes.
If your work hinges on having an accurate value for X, then you definitely should not use X if you cannot track down a reliable source for it. (Nor should you make something up.)
If you are using X just as a "sane" value for something, and it isn't central to your work, on the other hand:
If you think you have a better value than X, and can justify why you are using a different value than everyone else in your field, go ahead.
Otherwise, if you need a value, you should just use X (unreliable as it is). A bit of unreliable data that is accepted in your field is still better than a bit of unreliable data that you just made up with no justification.
Sometimes I struggle in choosing notations for a mathematical paper. There are probably no explicit rules, but unwritten conventions. In a discussion, is it proper to use different typographical variants of the same letter to denote different variables?
For example, is it acceptable to use an italic K (𝐾), an upright K (K), a blackletter K (𝔎) and a calligraphic K (𝒦) for four different variables in one section?
Answer
Enhancing on some of the other answers: while this is OK, and I have done this and worse in extremis (one of my papers is known as "the one with the four types of arrow"), your paper will be difficult to read.
You need to be aware of the fact that many readers will have a hard time tracking the differences between symbols. I recommend:
The statements of
"Applicants who are invited to campus for interviews must be able to show proof that they will be eligible and qualified to work in the United States by the time of hire."
is almost associated with every open academic positions in US and I am wondering what does this statement clearly mean?
As far as I know, academic positions in US are opened to the scientifically eligible candidates worldwide, but receiving US work permit requires a sponsor (employer) inside US who should initiate visa application.
My 1st question: Does this sentence show unwillingness of the employer (university in this case) to support applicants' visa application? Does this position only open to those residing in US? or work permit holders?
From the immigration website, I learnt that there are some costs for the employer who is offering job to an outsider. But, universities are exempted from paying the biggest chunk ($1500).
My 2nd question: Considering low visa petition cost, what else is the problem that US-based universities are hesitant to hire such candidates.
My 3rd question: Is faculty selection in US-based universities based on candidate's merit or there are other parameters when selecting them.
Edit: I think the email received from UW can be of help to get better idea of the situation.
Dear XYZ,
When completing your application for employment at the University of Washington you were asked to complete the US Work Authorization Assessment. The second question asked was:
To legally work in the United States, will you require University of Washington sponsorship for an H1-B, other UW sponsored visa, or UW sponsored green card now or in the future?
You responded yes, that you would need sponsorship, either now or in the future. As a result you are not eligible for employment in staff positions at the University.
I emailed to HR of UW for clarification with this note:
Does UW consider only those foreigners for staff position who are currently having work permit in US? Those who are willing to obtain work permit based on the UW job offer are ineligible to work in UW?
UW Reply (Though I think the reply is by a robot):
Unfortunately, the UW does not provide sponsorship for Green Cards( or HB-1 visas, or any other type of work authorization requiring sponsorship.) for staff positions.
EDIT 2: Though my question is about academic staff position, about university of washington, I applied for research scientist. Here is the link to the job opening.
I've been wondering lately how evolution manages to produce complex organs. It is pretty obvious to me how evolution would select some minor traits like size, resistnce to illness or climate. There is a mutation where some organisms are slightly different and better traits are selected. However I cannot imagine how an organism will mutate to have lets say lungs at once and unless organism has a functional organ there is no reason for the trait to be selected. So how does evolution produce complx organs?
Answer
The best introduction to evolution of complex phenotypes via master control genes is Endless Forms Most Beautiful: The New Science of Evo Devo and the Making of the Animal Kingdom by Sean B. Carroll. You might also want to have a look at a more recent Evolutional developmental biology (Evo Devo) book like those you get when searching for "Evo Devo" in Google Books.
In summary, it is possible for a mutation to change a shape by changing the spatial distribution of a transcription factor during embryo development. What's more, by changing the distribution of two mutually dependent factors, formation of any shape is possible if the distributions overlap. Such transcription factors are highly conserved in evolution and the most important cause of the endless forms we see.
When I cite papers online, especially in Wikipedia pages, it is very convenient to use their DOI. However, some papers which I would like to cite (like this and that) have no DOI. Or at least, I haven't been able to find their DOI in the crossref search form.
Why isn't a DOI assigned to all papers? Is there something I can do to change this?
EDIT: I now found out that in ResearchGate, I can upload my paper and it automatically receives a DOI. So practically, my problem is solved.
Answer
A process exists for obtaining DOI's, including the submission of meta-data and fees. Thus, it is time and cost prohibitive for some authors / publishers to obtain DOI's for their published works.
You can find information about DOI's here: http://www.doi.org/faq.html
I have finished my PhD and am currently a postdoc. Since receiving my PhD, I have not worked with my PhD advisor. I am planning to apply for jobs for after I finish my postdoc — mostly tenured-track positions.
I am considering not asking my PhD advisor for a letter of recommendation. I feel this might be appropriate because I plan to ask my postdoc advisor to write a letter, because my PhD advisor may not have kept up with my current research, because my coauthors know my work better, and for other reasons.
What are the pros and cons of not having my PhD advisor as a letter writer?
Answer
You should ask your supervisor for a letter.
Not having your supervisor write a letter is going to raise red flags. People are going to ask themselves, why isn't this candidate's thesis supervisor writing a letter? If you don't have a letter, you need to answer that question. Unless there's a very good reason to not have that letter, I think that it's better to avoid the question altogether. The reasons you've given so far do not seem good enough to me.
You suggested that (1) there may be more appropriate letter writers and that (2) your advisor might not be up-to-date on your current research.
I think these are not good enough reasons to not ask your thesis supervisor to write a letter and I think you can easily address these concerns:
You should also ask your postdoc supervisor to write you a letter. Not doing so will also raise red flags for similar reasons. If there are other great letter writers, ask them as well. For the tenure-track jobs I applied to, each expected three or more letters. There's room for everybody.
You can prioritize the more important or relevant letters. In your cover letter, it is normal to list the names of people writing you letters and it is normal to list those names in the order that you want them to be viewed. You can also specify in the letter which letters reflect more recent relationships, closer collaborations, or relationships closer to the core of your current research efforts.
It is not a critical problem if your advisor is not up to date on your current work. Presumably, their letter will talk the work that they know about and about your qualities as a researcher, colleague, and person that will not change. Also, you can point your advisor to or summarize the work you've done more recently.
I provided a copy of a draft cover letter, research statement, and teaching statement to each of my letter writers so that they could see how I was pitching and framing my work. I didn't do this because we were out of touch, but it seems like something similar would help address your concern.
I am most likely leaving my permanent position at my current university for a permanent position at a new university. I have been given an unofficial offer and we have agreed to terms. I have been told it could take over a month to generate an official offer and contract and that I should not give notice until then. I would prefer not to broadcast the news widely since nothing is set in stone until I am given the contact. Obviously I do not care that much since I am asking here.
In the few days I have known, I have told:
I am clearly failing at keeping it quiet. How do you not screw over your colleagues, but still keep the job change quiet until it is official?
Answer
This is common in academia. I think you have to be honest with everyone who might rely on you being at your current job in the future, let them know what stage you are at, and ask them to keep it to themselves until you get the official offer. You can only control what you say to others while asking others to respect your privacy in the meantime.
Suppose that you told everyone in your current department exactly what you have told us, and for some reason your new position falls through at this late date, what's the worst case situation you're worried about? It seems to me that, assuming your current job is held for you, your worst problems will be interpersonal with other faculty that resented your desire to leave. Is that it, or are you worried about some specific ramifications if word got around?
Update:
I found 8 students cheating in today's quiz despite stern warning and personal threatening to kick them out of the classroom if I notice cheating behavior again. 4 of them also likely cheated last time. The main reason is I left 5 minutes to fetch old quiz from last time.
I have reported this to the instructor and the two chairs of the department as well as sending the quiz sheets. I am very upset even though it "is not my fault". I have asked the professors explicitly that I do not to see these students in classroom again.
I work as a probability&statistics TA. During actual grading of the quiz papers submitted by students, I suspect some students are involved in cheating. The question is what I should do. I should note that my relationship with students is not the best judged from past experience.
The evidence that support my claim students were cheating in the quiz was follows:
During the quiz, I noticed students A, B, C, D, E, F, etc sitting very close to each other. I pulled their chairs apart and minutes later their chairs were close again. While I did not suspect cheating, I felt this is quite strange. In the end I have to pull their chairs apart three times. I also noticed they talking to each other, but I am not sure if they were borrowing the calculator or something. I simply did not suspect cheating.
During the actual grading I found the students A, B, C, D, E, F, etc all submitted work of very low quality and they made identical elementary mistakes like 1+1=3 on their exam sheets. This elementary mistake was carried through to the second part of the exam, such that a few of them did not bother to give any derivation to the wrong results in the test paper.
I have reported this to the professor, who avoided my email on any discussion with this topic. My questions are as follows:
For example, when I was an undergraduate, I was wrongly accused for cheating, and I knew such accusations makes people psychologically very uncomfortable even if turned out false in the end. While I am quite confident with what I found, I do not want to be the mean professor who treated me that way. I checked the university honor code and it says "the instructor should communicate with the students regarding the nature of the charge and the evidence...". I simply do not know what to say in this case. Should I simply say "I am suspecting you of cheating behavior, please explain yourself", or something?
But cheating behavior is far worse; it makes the normal Q&A process break down, and I simply do not know what feedback should I give to the students who cheated. It also makes life very unfair for students who made an huge effort but did not do as well as cheaters. I find it very difficult to prepare the lecture in the same mood again and pretend that this have not happened.
Answer
Addressing (3): You should check the policies at your institution, but a common rule is that the only person who can initiate academic dishonesty proceedings is the instructor of record for the course, ie the professor. This means that you cannot prosecute the students yourself; your job is to report what you observed to the professor, and let her handle it. (Note that references to "instructor" in university policies most likely do not include TAs.)
You say the professor is "avoiding" your emails about this, but how do you know? One possibility is that she hasn't received them, or hasn't read them; so you should contact her by some other means and ask if she got them. Once you have verified that she did, that is where your responsibility ends, unless you are asked to further explain your evidence, appear at a formal hearing, etc.
Another possibility is that she got your report and decided not to take any action. Again, policies vary, but most likely that is her prerogative. Maybe she thinks the evidence is not strong enough, or knows something about the disciplinary procedure that you do not, or simply wants to avoid conflict. Whatever. Her problem, not yours.
A third option is that she is taking steps to punish the students, but has not told you about it. Again depending on policies, she may not be allowed to do so; such proceedings are usually confidential, and you don't really have a need to know.
So in short: make your report to the professor, verify that it was received, and move on with your life.
I'm a professional programmer with 15 years of experience, working in game development as a game and engine programmer, currently working at a prestigious game company on two well known games.
I've submitted a paper to a graphics journal (jcgt.org), and am waiting on the review process. (2.5 months into an expected 3 month process!)
In the meantime I'm working on a computer science paper which doesn't pertain to game development, but is more related to cryptography and metaprogramming.
That realm is a little bit more of a challenge for me since it isn't my area of expertise, so I don't know as many obscure things, proper terminology, or what people expect to see, etc.
How would someone like myself - who is a professional with no academic ties - find a more academic minded mentor who knows more about these areas, that I could ask questions to, bounce ideas off, etc?
Or is that even a likely possibility?
Answer
I think it this can be achieved. Here are some thoughts on how I would do it.
Many academics lack practical skills but require practical skills to evaluate and test their theories and get the publications they desire. These are the kind of academics who will be interested in working with you. To find them, you should first find areas of research that you are interested in where your skills are relevant. Find researchers in those areas who are looking for people with skills you possess (look for what they want for their funded PhD positions and Post-doc positions). Based on this information prepare a clear value proposition - a set of things which you can offer the researchers, and what you would want in return.
Make contact. Ideally do this through a mutual connection who is well liked and respected. If that is not possible then you should try to talk with the academic face to face or on the phone so you can make it as easy as possible and create trust more quickly. Academics are often very busy and cautious of having their time wasted so this is important.
The suggestion above might seem like it involves too much commitment, but you will almost definitely need to show you can provide some sort of return for an academics time before they will work with you so unless you can show how working with you will get them publications or grants they probably won't be interested in helping you with your personal interests.
With that considered, if you are successful with your journal publication you will have a much better chance as the academics will be able to see that you have what it takes to write papers and thus infer that you will be likely to be able to get more publications with relatively little help from others.
A student asked me to write a letter of recommendation for graduate school admission in London and the student insisted that I include a short biography describing my job title and qualifications. I find this information is a little out of place. First, my degree is in progress, so I do not have any impressive qualifications. Second, I think such letters are intended to introduce the applicant, not the writer.
Answer
You are right, the point of the letter is entirely the candidate, any sentence(s) about yourself should be entirely to the point of facilitating communication about the candidate. I was told in school that all histories tell you as much about the culture that wrote them as the culture they describe, so you need to take both into account when you read them. I suppose this is true of reference letters as well. It's like introducing yourself before you ask an academic you don't know a question one-on-one over coffee at a conference – sometimes there's no need, but sometimes it's essential to framing the question & making the most of the other person's time & answer.
I have never been explicitly asked for a biography beyond "how do you know the candidate, for how long, and in what capacity". However, the UK is under a lot of legal pressure concerning letters of reference because some are so much better than others, not necessarily due to the candidate, but possibly due to how knowledgeable the writer is about writing letters. Possibly candidates deserve some credit for picking good letter writers, but this could be hard particularly for very junior candidates. So having guidance for writing a letter is useful, it's letting all letter writers know good practice by previous letter writers.
Personally I include biographical information (not a full biography) where I think it may be helpful and when I am trying to write a strong letter. Similarly, I also give information about our institution where I think it might not be known and be helpful. Examples: if I am writing a US institution from the UK, I let them know that I have attended US institutions & know what their programmes are like. Sometimes if I know someone well in the department I may point that out in the letter so that whoever is doing the search has the option of going to ask that person how seriously to take my opinion if they want to.
I put this at the end of the first paragraph or possibly as a stand-alone second paragraph, in advance of offering my verbose opinion of the candidate, so that the reader can have that information in mind when they see what my opinion is. The first sentence of the first paragraph says who the letter is for & for what position. The second sentence is my one-sentence summary of my recommendation. The third (or the second paragraph) is in what capacity I am writing the letter. That's where biographical details might be useful.
I notice that after long tests, or long periods of critical thinking, my body and mind feel noticeably tired. Why does this happen? Are the neurons in my head not firing as quickly, or is there just a perceived lack of mental concentration?
What exactly is the mechanism that makes my brain feel worn out, or at least gives me the perception of my brain being worn out?
Answer
There is ongoing research on this topic, but there is a theory known as inhibition theory. It has been defined as:
Inhibition theory is based on the basic assumption that during the performance of any mental task requiring a minimum of mental effort, the subject actually goes through a series of alternating latent states of distraction (non-work 0) and attention (work 1) which cannot be observed and are completely imperceptible to the subject.
For a more in-depth explanation, see this paragraph from Wikipedia:
Directed attention fatigue occurs when a particular part of the brain’s global inhibitory system is overworked due to the suppression of increasing numbers of stimuli. This temporary condition is not a clinical illness or a personality disorder. It is rather a temporary fatigue of the inhibitory mechanisms in the brain. According to inhibition theory, it is natural for one to alternate between periods of attention and distraction. Although one’s efforts may involve very different tasks, each incoming stimulus calls upon the same directed attention mechanism.
or this paragraph from NCBI:
Recently, it has been shown that the neural mechanisms of mental fatigue related to cognitive task performance are more complex than previously thought and that mental fatigue is not caused only by impaired activity in task-related brain regions. There is accumulating evidence supporting the existence of mental facilitation and inhibition systems. These systems are involved in the neural mechanisms of mental fatigue, modulating the activity of task-related brain regions to regulate cognitive task performance.
In short, it is now believed that the brain contains mental facilitation and inhibition systems, which control mental freshness and fatigue. Basically, when you concentrate, you actually stop all distractions from taking over (and not give more focus to the main point). This mechanism is governed by the inhibitory system of the brain. After some time, this system stops working ('it gets tired') and you become unable to pay attention towards anything. That's why it is advised that after some time of concentration, you need to distract yourself (to refresh your inhibitory system); like, say, while preparing for exams, you should have a break of 5-10 minutes after studying for about 45 minutes.
Now, why mental tiredness causes physical fatigue can be (I think) summarized by the diagram below from here:
The exact process at this part is rather very interesting. Here, the neurons are not firing as quickly as they do normally. See this Wikipedia page:
Physical fatigue can be caused by a lack of energy in the muscle, by a decrease of the efficiency of the neuro-muscular junction or by a reduction of the drive originating from the central nervous system. The central component of fatigue is triggered by an increase of the level of serotonin in the central nervous system. During motor activity, serotonin released in synapses that contact motor neurons promotes muscle contraction. During high level of motor activity, the amount of serotonin released increases and a spillover occurs. Serotonin binds to extrasynaptic receptors located on the axon initial segment of motor neurons with the result that nerve impulse initiation and thereby muscle contraction are inhibited.
The same might happen in the case of mental fatigue i.e. the excess serotonin released from frontal or parietal lobes, or even the inhibition system itself, can cause the same effect i.e. inhibition of muscle contraction.
References:
