evolution - Are there any multicellular forms of life which exist without consuming other forms of life in some manner?

The title is the question. If additional specificity is needed I will add clarification here.

Are there any multicellular forms of life which exist without requiring the consumption (destruction) of other forms of life in some manner? Thus purely on inorganic material.

I do understand that the definition of life is a semantic distinction, so for this discussion I will assume the one Wikipedia provides:

"Life is a characteristic distinguishing physical entities having signaling and self-sustaining processes from those that do not, either because such functions have ceased (death), or because they lack such functions and are classified as inanimate. Biology is a science concerned with the study of life."

I am open to considering alternative suggestions.

Thank you.

teaching - In-class, allowing students to address professor informally ('tutoyer' / 'tutear')

Supposing that Dr. A is teaching an undergraduate-level course, what would be the pros and cons for Dr. A to allow students to address himself in an "informal" manner?

By "informal" here I mean using what is employed in a number of languages for informal conversation. For example, this would be tutoyer in French or tutear in Spanish. (Hence, the question does not apply for an English-speaking classroom, but does apply for a French or Spanish-speaking one).

EDIT (clarification, thanks j91): In Spanish, French, German and other languages, the second person singular has two versions: "Tú", "Tu" and "Du" are the informal versions in Spanish, French and German, respectively, and "Usted", "vous" and "Sie" are the formal ones in the same order. "Tutear" is the act of using systematicaly the informal version and, in theory, should be avoided when speaking to a person in a position of authority.

Answer

The effects of the decision to invite your students to address you informally, and whether this is considered appropriate at all, are very culture-dependent. In general there are several trade-offs. How you balance them depends on your personal judgement. My experience is that of a German who has worked both in Germany and Austria.

Possible upsides of having the students address you in an informal manner (tutoyer/tutear/duzen) include:

• Students may be less concerned about perhaps embarrassing themselves in front of the "authority figure"; they may be more inclined to participate in class discussions and ask ("stupid") questions.



• Less perceived role conflict on your side, if you are a very junior lecturer and empathize more strongly with the student side than more senior staff.


• A more relaxed and friendly atmosphere in general

Possible downsides:

• Students may be more willing to negotiate about grades etc.; and less distance between you and the students can make it hard to say "no"


• Politely ignoring each other can be harder if you encounter students in a different social setting


• Explaining or even just giving a disappointing grade feels more personal and unpleasant when you have crossed the line between you (tu, Du) and "You" (vous, Sie).

career path - Postdoc opportunities in mathematics

I am expected to finish my Ph.D in mathematics (if relevant, more specifically - in commutative/homological algebra) by the end of this academic year. I am studying in a somewhat minor university, although my supervisor is a well know figure in his field.

Following my supervisor's advice, I submitted applications for postdoctoral positions in about 20 top level universities in the US. As most of these universities already finished hiring for this year, I suspect I made the mistake aiming too high, and would probably get negative answers from all the different employers.

Assuming this is the case, I am now wondering what should be the next step in my academic career. One option is to stay at my current university for another year (but with a much lower salary, as my scholarship will come to an end). I should mention that my supervisor highly discourages this option, as he thinks that I should get more involved in the research community of my field, and my current university is a poor place to do so.

Alternatively, I am wondering if there are any other opportunities for postdocs in Europe or the US for the 2013 academic year, in my relevant field, of which the deadline still did not pass.

Any advice or idea for my situation would be helpful.

Thank you

Can I force evolution in a group of cells by removing all the smaller cells?

I actually have algae growing in water in a container. I was thinking if it was possible to filter the water so that all the small cells will be filtered out and only the bigger ones will remain to reproduce cells that tend to be bigger. Is that possible? What type of filter should I use?

plagiarism - Professor does not care about cheating, what should TA do?

I am a PhD student, working as a Homework marking TA in a school where cheating is extremely blatant. The university has an extremely strict policy against cheating. Hundreds of students in math courses alone are reported each year, and suspensions are given to severe/repeat offenders. I have personally reported cheating many times.

Based on this environment, most courses have shifted away from Homework grades, and more toward Quiz/Test grades.

My course is a low-bar mid-level math course, very likely to be the last math course ever taken by the students who enrolled in the course.

The marking distribution of my course is done in a way where the homework mark weight is so absurdly high that cheating on homework would almost guarantee a pass.

I had realized this at the beginning of September, and discussed with (confronted) the instructor. The short summary of the response is that the instructor doesn't care about cheating.

The professor doesn't want to put in the effort to deal with cheaters. The professor thinks the students cheating would not be overly unfair to other students who don't cheat. The professor also does not want me to try to catch cheaters.

I have made clear that cheating on homework almost guarantees a pass, and he/she agrees, and is ok with this.

The homework are all questions from the textbook, and a solution manual is readily available on google.

In this week's homework, I have found more than 100 students who have copied from the solution manual, where at least 50 students copied word for word (if reported, the cheating done can be easily proved by the school.)

I suspect I only caught a portion of all cheaters, as buying solutions at this university is too blatant.

I would like to ask the community of my next steps.

If I were to report the cheating to him/her: Would I anger the professor, since this is against his/her wishes? Would I build a tense relationship with him following this? (There is still a whole semester ahead, and possibly years in the same university.) What would be done in the end? What if he ignores the report, what should my next steps be?

If I were to report to the undergrad chair: Would it be inappropriate to skip reporting to instructor first? Would I also build a tense relationship with the instructor by this move? I am almost positive that there would be action by the undergrad chair on the cheating behavior.

I could also report to both simultaneously. I could also do nothing at all, in which case the cheating would without a doubt continue for the whole term, with the vast majority of students taking part.

I personally disagree with the professor, as I believe that it is unfair for the minority of students who don't cheat. Due to the high homework marks, a mark curve is highly unlikely, so the students who don't cheat are truly getting lower marks because of the cheaters.

The instructor is in the beginning of his/her career, and not retiring. The university is in North America, very large (more than 50,000 undergrad)

Edit3: As I continue to grade, I have found more and more cheaters, in the hundreds, approaching 50% of the class.

Thanks for all the suggestions asking me to "let it go". After much consideration, I can not take such advice.

Thanks for all the suggestions of asking me to "not skip the chain of command". I have since realized this may have severe consequences, and have decided against it.

I have contacted only the instructor with minimal details of the situation. Thanks for all the support and best wishes from the community, I sincerely appreciate it.

Recommendation Letter Request: No response

I am applying to graduate school, and I am having a problem with recommendation letters. I need three recommendation letters with two of them being academic reference letters. Honestly, last year, I had requested two recommendation letters from two of my former professors for my law school applications. However, in the end, I decided not to pursue law school for a number of reasons, despite being accepted to one. Currently, I am applying to a number of different schools' masters' programs in the field I plan to study.

As I mentioned earlier, I am having difficulty with the recommendation letter process. I wrote emails to those two professors about my situation, and one professor was willing to revise her former recommendation letter for my new masters' programs applications. However, I have yet to hear back from the other professor. I had written a senior thesis under that professor, and I was hoping to receive a letter from him. After I sent an email to that professor a few weeks ago, and received no response, I sent him a follow-up email yesterday. I received no response to that follow-up email either. If there is no response, does that mean a discreet "no"? Should I send another follow-up email a few days later? Or, should I find another academic recommender at this point? My first application deadline is in the middle of December.

behaviour - Why do humans suffer anxiety when they view "Trypophobia trigger images"?

When you type Trypophobia Trigger Images in google, you see a variety of images with irregular lumps and bumps among some more gory images.

Many people report that these images induce phobia like symptoms of anxiety.

Why do we get anxious when exposed to these images? What advantage is there to be had from this response?

I find the reasons like this ABC news report on ants and spiders. But still didn't get it any info from it.

Answer

Trypophobia is not a recognised specific anxiety disorder (Washington Post). It is worth mentioning that anyone can have a phobia to anything, this is merely a question of whether many people associate these spatial patterns with anxiety. Nevertheless, the response of individuals to these images can be quantified (Le et al., 2015). Ultimately the findings show that a response of trypophobia is not correlative with anxiety. Note that here we are discussing anxiety in a phobia response test. Typically anxiety manifests as sweating, dizziness, headaches, racing heartbeats, nausea, fidgeting, uncontrollable crying or laughing and drumming on a desk. This is not merely feeling uncomfortable.

One hypothesis was that these images had irregular spatial patterns that cause revulsion. A study found that in nature some animals and plants may use this patterning as a warning mechanism and that it is associated with poisonous animals (spatial pattern quantification of 10 poisonous animals versus 10 control animals p=0.03), and indeed spiders were among those that use irregular patterns (Cole & Wilkins, 2013). Note that this hypothesis was presented in a psychology journal so the evolutionary mechanisms remain, in my opinion, not fully explored and scrutinised.

Hover over the below yellow box to view a lotus seed head, which has typical irregular spatial patterning presented in the 2013 study.

This image is often reported as inducing trypophobia.

Answer: In summary, humans do not reliably feel anxious when viewing these images. It also remains unclear why some people do get anxious or uncomfortable when viewing these images. It is perhaps to do with an aversion to some potentially harmful animals, but evidence remains scarce.