Notes on 3D-Printed Face Shields

Face Shield

Printed from a design by Doug LaRue available here:

 

Use

This will hold a letter-sized sheet of overhead transparency material firmly in place. The 3D printed face shield itself might feel flimsy, but the curved transparency material locked into it provides structural integrity.
 

My friend wearing one of the shields.

Here are the designer’s instructions for inserting the transparency:
HOWTO:
1)Insert film by deflecting the outer rim at the front just enough to see the inner rim.
2)Then while holding the deflected outer rim, insert one corner of the film towards one earpiece and release the deflected outer rim.
3)Working from that side, pull the film through the slot equally all the way around.
4)Slide the outer rim back into place thereby locking the film between the two rims.
 It is easier to do than these instructions sound – just try it.
 
The earpieces should hold the face shield securely. If desired, a rubber band or some chained hair ties can be secured to the hooked ends of the ear pieces to go around the back of the head.

Material

The shield is made of polylactic acid (PLA), described in detail here:
 
https://campus.albion.edu/wjwilson/2020/04/08/notes-on-3d-printed-face-shields/
PLA is a product of plant starch (typically corn). The PLA will melt at around 150 degrees C, so it cannot be autoclaved, but a means of sterilizing it is described here
including a regimen of wiping with 70% alcohol, soaking in a 30% KOH solution, and “a round in an ethylene oxide (EO) gas oven designed specifically for sterilizing plastic medical equipment.”

My Printer Settings:

Printer: Creality CR-10 300
 
Bed temperature: 65 deg C
 
Nozzle temperature: 210 deg C
 
Layer height: 0.2 mm
 
Infill: 40% (rectilinear)

No supports

(The above represents my preferred settings for this shield; at a print speed of 40 mm/s for perimeters and 60 mm/s for infill it takes about 2.5 hrs to print one. I have printed some at different settings, e.g., 0.3 mm layer height and 0% infill, higher printing speed; this reduces the print time to about 1.2 hrs, but results in a flimsier shield. These faster printing shields likely work fine, but they are far less sturdy. EDIT: Constantly working to improve print speed while retaining quality. These settings are subject to change.)

 

Robert Rescorla

Robert Rescorla

Bob Rescorla, a giant of modern learning theory, died recently. Although I did not know him well (met him twice) I have great respect for him and his work. Together with Allan Wagner, he created a model of Pavlovian learning that drove the understanding of classical conditioning from the 1970s to the present. Their model’s importance was recognized by the Pavlovian Society: Rescorla won the Society’s Gantt Medal in 2005, Wagner in 2009.

The Rescorla-Wagner Model proposed that learning occurred when reality did not match expectations, that is, when there was surprise. Importantly, this approach suggested that expectations were based on all available information: Pavlov’s dog learned that Tone meant Food because the dog did not expect Food on the basis of the Tone and all other available cues. If Tone happened at a time when the situation meant food was imminent (e.g., Pavlov was opening the can of dog food), then there would be no surprise and the dog would not learn an association between Tone and Food. Their model offered a mathematical approach that allowed explicit predictions that could then be tested empirically. The Rescorla-Wagner Model was not perfect and was overly simplistic (Rescorla and Wagner knew this) but it provided a starting point for refinements that have come closer to the truth.

Rescorla was born in 1940, did undergraduate work at Swarthmore College, and completed his PhD at University of Pennsylvania. Since 1981 he was on the faculty at U Penn. His page at the U Penn Psychology Department web sites states “The long-term goal of the research is to provide a characterization and theoretical understanding of simple associative learning.” I believe that he met his goal. 

Thoughts on Bucking Bulls

When I’m not professoring, I am a photographer. I frequently shoot bull riding, and a photo I posted led to discussion of how the bulls feel about it, and then to possible autonomic nervous activity and what that can tell us (there is no off position for the neuroscience mentality). I post the discussion here, with other people’s names removed.
 

Photo that started the discussion. Bucking bull, spewing lots of saliva.

 
Animal Learning Person: Great shot! Are they…in pain?
  • Me: I went into rodeo photography with eyes wide open to abuse – my animal research, IACUC, learning theory background all made me hyper-aware of this. I have seen little if any abuse. The stock contractors who raise the bulls and provide them to the venues treat them well – the bulls are their income. At the rodeos the bulls are ridden at most twice a night (usually just once), and then at most for 8 seconds – usually much less. Once the rider is off the bulls typically jump around a bit, then trot out of the arena – they are well-versed in the protocol, like a rat running a maze. I don’t know if they like bucking–I suspect that it is driven by some instinctive anti-predator behavior, but I don’t think they are in pain.There are frequent reports of bulls being shocked to make them buck more. I have never seen this. I _have_ seen, twice, a bull that is shocked to get it to stand up if it has lain down. Given the bull’s thick hide, I suspect that the subjective experience is similar to a human getting a static shock (but this is conjecture). Here’s a statement from the Midwest Bucking Bulls Association rulebook about this:—————————–
    ELECTRICAL DEVICES & FOREIGN OBJECTS:
    All electrical devices used to stimulate the animal cannot be used while he is in chute, unless the bull is leaning bad or
    squatting, and he won’t stand correctly. Contractors or MBBA personnel are prohibited from hot shotting any bull while he
    is leaving the chute. Foreign objects in flank will not be allowed. Any owner that is not following this rule is subject to
    disqualification of the animal involved in the particular incident, and total disqualification from the competition and they
    will forfeit any entry fees. In addition, failure to adhere to this rule could result in suspension and fine as outlined in
    MISCONDUCT & CHEATING.
    ——————————

    The bulls are trained to buck (or rather chosen for their ability to buck) when they are 1 – 2 years old. A dummy weight (around 20 pounds) is placed on their back, and they are judged based on the effort they make in bucking it off. Selective breeding has resulted in bulls that are quite adept at doing this dramatically, and the ones who do it well are highly valued. I assume that the bulls that fail become meat, but that is true of most cattle, and we could have another different discussion about animal treatment at the slaughterhouse.

    So, do they feel pain? I don’t think so. They are viewed as prized athletes and treated as such. I doubt that many people involved with rodeo think about this as deeply as I have, but I think they care about the health and well-being of the animals. Would the animals rather be grazing idyllically on the grasslands of the US? Probably, if they knew about that option, but in comparison to most domesticated cattle I think the rodeo bulls have it pretty good.

    And I recognize that my views might be colored by my involvement in the sport. As a behaviorist I try to be objective, but as a psychologist I recognize the possibility of bias. Always open to additional information…

    • Animal Learning Person: Thank you for the great information. I have long felt that you wouldn’t be involved in this if there was abuse involved. I had to do a lot of research on zoos and circuses in order to get involved in elephant research. That is why I chose elephant habitation as the topic for my honors thesis. I needed to understand as many aspects of the entire situation as I could. As with the rodeo, people often form opinions about zoos and circuses based on assumptions and emotion. But I talked to enough keepers and trainers to see the obvious love, respect, and care that goes into each and every animal they are responsible for. Being an animal lover at my very core has, on occasion, made it complicated to pursue quality research without allowing emotion to cloud my efforts. Before I get too far off topic, I will wrap this up. But thank you for your thoughts and information on this. Having no experience with the rodeo, I simply didn’t know. It eases my mind to know that you feel this way.
  • Neuroendocrinology Prof:  I must admit, I wondered the same thing upon seeing the spittle/mucus from the bull’s mouth. What causes that? Effort? Adrenaline usually dries one out.
    • Me: Neuroendocrinology Prof – I’m not sure why the saliva, but it is plentiful. Perhaps it’s evidence of more parasympathetic than sympathetic activation at this time, suggesting that the primary emotional experience is not fear or something aversive, but instead something like “workday’s almost over – time to go chill for a while.” Maybe similar to a student’s experience as an exam ends?

    • Me: Neuroendocrinology Prof –  And on a related note, it is not at all unusual for the bulls to sport an erection while bucking – additional evidence of parasympathetic activity. I’ll post a photo when I find one.

      Bull with obvious erection while bucking. Note: erect penis is pink; testicles are swinging forward by the bull’s rear legs.

       

       

Animal Learning Scientist and Horse Person: Honestly naive question: is a “bucking strap” cinched on the bulls like is done with the broncos?
 

Another flank strap photo.

Photo showing the flank strap.

  • Me: There is a “flank strap” that goes around the bull’s hindquarters. Ostensibly is makes them buck more – perhaps initially (i.e., early in training) adding to the simulation of threat. I think by the time the bulls are experienced it serves more as a discriminative stimulus – signalling time to buck.  

    It does NOT affect the testicles at all — I’ll try to find a photo that illustrates this) — but it does cross the area between the testicles and the penis, so there is almost certainly some genital stimulation produced by it.

     

Science: It be like this.

Once More, For People in the Back

I’ve grown tired of repeating myself in comments to anti-LGBTQ posts on various social media; this post is a summary to which I can simply refer people in the future.

[tl;dr: Gender is in your brain, not in your pants.]

There is growing evidence from biology and from neuroscience that sexual behavior, sexual preference, and gender identity are far more dependent on the brain than on the genitals. Here is a quick synopsis. I’ll provide a few references at the end for people looking for more information.

  1. Mammals typically have either XX or XY sex chromosomes. The function of these chromosomes in determining sex or gender is somewhat limited, and depends mostly on the presence of the gene Sry, that is most commonly on the Y chromosome but that can in fact sometimes occur on an X chromosome.
  2. Sry causes the primordial gonads to become testes. In the absence of Sry, the gonads become ovaries.
  3. The gonads then secrete hormones: mostly androgens from the testes and estrogens from the ovaries.
  4. The presence of testosterone and of other androgens during early development leads to masculinization and defeminization:
    1. The primordial phallus becomes a penis.
    2. The labia fuse into the scrotum.
    3. The male internal reproductive organs (Wolffian system: prostate, epididymis, vas deferens) develop and the female (Müllerian system) is suppressed.
    4. Index finger growth is stopped, resulting in a shorter index than ring finger on average.
    5. Inner ear changes result in a decrease in later otoacoustic emissions and poorer hearing
    6.  Brain is masculinized.
  5. The absence of androgens during early development leads to feminization and demasculinization:
    1. The primordial phallus becomes a clitoris.
    2. The labia remain unfused.
    3. The female internal reproductive organs (Müllerian system: Inner part of the vagina, fallopian tubes, uterus) develop and the male (Wolffian) system does not.
    4. Index finger growth continues, resulting in an index finger equal to or longer than the ring finger.
    5. Inner ear changes increase the occurrence of otoacoustic emissions, leading to better hearing.
    6. The brain is feminized.

The effects detailed within 4 and 5 above are largely independent. Typically they all proceed in the same direction, but that does not have to be the case: an XX individual might be born with female genitals but a male brain, or vice versa.

Adult sexual behavior in nonhuman mammals is determined almost exclusively by the effects of adult hormones on the brain (whose sex was determined in development):

  1. Androgens affect the male brain to produce male-typical sexual behavior.
  2. Estrogens affect the female brain to produce female-typical sexual behavior.

NOTE: By “male” or “female” brain I mean a brain that was masculinized by testosterone (“male”) or feminized by the lack of testosterone (“female”). It does not matter at all what sex chromosomes the organism has. It is also possible that the genitals were masculinized and the brain was feminized, or vice versa. All that matters is how the brain was organized.

In humans, adult hormones are linked to sexual behavior, but do not have quite the same strong effect as in most nonhuman animals. Apparently in humans, whose young require a very long time to mature compared to the young of most mammalian species, sexual behavior occurs readily throughout the hormonal cycle, promoting a pair-bond (love) between the parents that keeps them together to care for the young. 

Sexual orientation and gender are hard to study in nonhuman animals, but there is general agreement that early brain differentiation as a result of the presence or absence of testosterone plays a role here as well.  Male mammals have a large third interstitial nucleus of the anterior hypothalamus, while the female INAH-3 is small. This area is known to play an important role in male-typical sexual behavior. Gay human males have an INAH-3 that is on average the size of the average female INAH-3. The bed nucleus of the stria terminalis (BNST) is larger in people who have a male gender identity (regardless of what the genitals look like) and smaller in those with a female gender identity. That is, both cis and trans males have a large BNST.

The best way to determine someone’s gender is not to look at their genitals, but to ask the brain. Brain gender trumps genital gender.

 In summary: brain differences that relate to sexual behavior, sexual orientation, and gender identity develop as the brain develops. These brain features are far more determined by hormones than by genetics, and are unrelated in any causal sense to the genitals. The brain features do not represent the effect of a choice; rather those brain features determine gender and orientation.  The brain appears to be born with a gender identity and with a sexual orientation.


I recognize that much of what I have written reflects the influence of the heavily cis-, binary- and hetero-normative culture in which most of the research was done. Give us time – neuroscience will develop the language and strategy necessary to address the complex spectra that are gender identity and sexual orientation.  See Arnold & McCarthy (2016) for a start.


Arnold, A. P., & McCarthy, M. M. (2016). Sexual differentiation of the brain and behavior: A Primer. In D.W. Pfaff, N.D. Volkow (eds.), Neuroscience in the 21st century. New York: Springer Science+Business Media.

Breedlove, S. M., & Hampson, E. (2002). Sexual differentiation of the brain and behavior. In J. B. Becker, S. M. Breedlove, D. Crews, & M. M. McCarthy (Eds.), Behavioral endocrinology (p. 75–114). MIT Press.

Hines, M (2010). Sex-related variation in human behavior and the brain. T rends in Cognitive Sciences, 14, 448-456.

Savic, I., ed. (2010) Sex differences in the human brain, their underpinnings and implications. Amsterdam: Elsevier.

Mike Eisenberg

Mike Eisenberg

l learned today that a friend from college — a suite-mate from my first year at Haverford — passed away in March. I had some contact with him in the 1990s, and was glad then to learn that he was leading a fulfilling and happy life. Here are some memories that I want to be sure are recorded in case anyone else is interested.

My memories of Mike Eisenberg

from https://twitter.com/bpenuel/status/1140976105253429249/photo/1

Mike was in my suite in Gummere our first year at Haverford. It was a three-person suite, but overcrowding that year meant that there were four of us in it – the living room was a bedroom. Sadly, the fourth person, assigned to the living room, spent most of his first year in the infirmary with hepatitis, so we essentially had use of the living room. Mike, Chris Billy, and I were the three suitemates.  My memories of Mike are strongest early in the year, largely because I found myself spending increasing amounts of time with a girlfriend at Bryn Mawr as the year progressed.

  1. In the summer before our first year I phoned my soon-to-be suite-mates. I recall liking Mike immediately — this was the summer of 1973, and our discussion centered on the troubles facing then-President Nixon. We were both anticipating the end of his presidency with glee. When the infamous 18.5-minute gap in the secret White House tape recordings was revealed in November, I remember Mike and me marveling at the explanation of how Rose Mary Woods had managed to create that erasure accidentally.
  2. During our first few days at Haverford, Mike asked for my help retrieving a trunk of possessions that had been shipped to the College. It was large and heavy; Mike was, well, diminutive; the trunk might have weighed as much as he did.  I recall carrying it on my shoulder back to the dorm, working up a tremendous sweat. Mike was grateful, and I was glad to help.
  3. At some point during the year Mike returned to the suite to discover that someone had placed pictures of nude women all over his room. He was mildly amused, and a bit upset at the fact that someone had gained access to his space. He was livid and especially troubled when he found a picture inside his violin (viola?) case – this was going too far in his eyes. The instrument was undamaged (as far as I know), but he was visibly disturbed and angered by this intrusion.  I have no idea who perpetrated this act, although I think Mike probably found out.
  4. I recall several animated discussions about language learning in chimps. We were all fascinated by the studies, and Mike especially wanted to extend the chimps’ language to situations that had not yet been examined. I don’t recall any specifics, only that Mike took great joy in mimicking the presumed responses of the apes to unexpected events.
  5. Mike recounted an embarrassing moment from high school, when in a class discussion he talked about someone “misling” someone else. People were confused, which he didn’t understand, and he tried to explain by saying, “You know, to misle.” He had never heard the word pronounced–his confusion came from having read the word “misled” with a reasonable but incorrect pronunciation.
  6. In discussing the difficulty of some courses, especially courses in the pre-med curriculum, I recall Mike suggesting that the College’s motto should be, “Haverford College: We’ve got a buster for every ball you can muster.” I don’t think this was ever officially adopted.
  7. There were several Sunday mornings when Mike and I worked the NY Times crossword puzzle together. To be honest, although I love the puzzle, this was not much fun for me.  I learned a lot, because Mike was exceedingly good at it. He had had two crosswords published by the New York Times before coming to Haverford. [Edit: I’ve looked for these puzzles, without success. I found one published in Dec 1974, after I met Mike, but the two earlier puzzles elude me. I cannot imagine that Mike was dishonest in saying that he had done this, so if anyone comes across the earlier ones please let me know.]
Sadly, I think it was the pressure of the pre-med curriculum that caused Mike ultimately to leave Haverford.  He would have been a great physician, but I am happy that he found a life’s work that brought him much joy. I am not surprised that he was very good at it.

Rest in peace, my friend.

Looking Back after SfN 2019

Another Society for Neuroscience meeting is in the books. More than 27,000 people came together in Chicago, all sharing some kind of interest in the brain or nervous system. Some engage in basic research, some work on clear clinical applications, some were there to sell goods to anyone who would buy. More than 8,000 were students, many of whom will make important contributions. Seven of the students there were Albion College neuroscience students.

Tony Reiner, Alice Powers, and me.

I attended my first SfN meeting in 1977, and every SfN meeting from 198o through this year except for 2009 Chicago meeting (I was in Poland at the time). That’s 40 meetings. I’ve had the chance to interact with many wonderful scientists and great people (and some who were both). Among my favorite memories of earlier meetings:

  • 1982, Minneapolis: Running into my first Psych prof, Alice Powers, at breakfast in the tremendously overcrowded hotel restaurant. I’ve seen her at just about every meeting since.
  • 1987, New Orleans: The first Bryn Mawr get-together that I recall. We’ve had these many times since.
  • 1989, Phoenix: Stayed at my brother’s condo (he was out of town). Neuroscientists overran the city, to the point that even the Subway that I went to for lunch was out of bread.
  • 1991, New Orleans: First gathering of the group that was to become Faculty for Undergraduate Neuroscience (FUN). Here’s a history of FUN.
  • 1994, Miami: Hurricane (or remnant of a hurricane) made its way back and forth and back across the city.
  • 2000, New Orleans: First Albion student trip to SfN; I arranged for Ned Garvin to play Cajun Accordion with Lee Benoit’s band at Mulates.

And among my favorite memories of people meeting with my students:

  • Candace Pert (co-discoverer of the endorphins).
  • Dick Thompson (wonderful, caring scientist who met with us several times).
  • Ramachandran (on several occasions, including visiting with him at his lab).
  • Catharine Rankin (convincing students that even invertebrate neuroscience and behavior is worthwhile).
  • William Calvin (love his book The River that Flows Uphill).
  • Joe Ledoux (of Amygdaloid fame).
  • Debra Bangasser (who routinely meets with my students to offer great advice).
  • Jim Pfaus (who disturbed some more conservative students with his frank talk about sex at Albion).
  • Rodolfo Llinas (who visited the Atlanta Aquarium with my students after having lunch with us).
  • Ki Goosens (who has the best, most amusing story of personal terror I have ever heard).
  • and many, many post-docs and grad students who had profound effects on my students, including Moriel Zelikovsky, Erin Young, Kyle Baumbauer, Marieke Gilmartin, Robert Twining, Sydney Trask, Nicholas Singletary (who will be famous one day), and many more (my apologies to those I failed to mention — I truly appreciated your time spent with us).

Here are some photos from the 2019 meeting.

Historic Photo Comparison

In 1908 Winston Churchill campaigned for a seat in Parliament. In Dundee, Scotland, he was pestered by Mary Maloney, who followed him with a large bell, ringing it whenever he spoke, as a protest against his earlier comments against women’s suffrage. I saw a Facebook post about this, and Googled to do some fact-checking (the story is apparently true). However, I noticed that the photo that accompanied the FB post (top photo below, source not given) is not the most common one used to illustrate this piece of history. Instead, the lower photo, from the London Evening News, is far more often seen. 

 

The Evening News image clearly shows Maloney holding a bell – this is not nearly as obvious in the FB image. The difference that immediately caught my eye was the audience – clearly several women listening in the FB image, none visible in the Evening News image. I thought that maybe the Evening News image had been altered to create the FB image, but that is clearly not the case as they are two distinctly different photos. See the comparison photo below.

In the side by side comparison, you can see that in the Evening News image Maloney obscures the second tall window (A) – in the FB image that window (A’) is not blocked by her. Similarly, the two guys hanging from the window (B) in the Evening News image are obscured (B’) by Churchill in the FB image (or possibly any vestiges of them have been edited out).  The small guy (C and C’) in the window behind Churchill in the Evening News image is obscured by Light-Colored-Hat guy (c and c’) in the FB image.  Finally, I believe that the woman in the light-colored hat in the FB image (D’) appears in part in the Evening News image (D).

A bit of elementary geometry and some thinking about perspective will lead to the conclusion that the FB image was taken by a photographer about 8 feet to the right of the camera that took the Evening News image and considerably further away from Churchill.

Cameras were not omnipresent in 1908, so it is likely that the FB image was taken by another press photographer–after all this would have been a newsworthy event. The FB image is used with the caption “WSC addressing suffragists, Dundee 1909” to illustrate an online piece by Richard Langworth, a Senior Fellow of the Hillsdale College Churchill Project. I’ve contacted him to see if he can offer a source for the image. [5/20/19: He cannot.]

I geek out on old photos, and find it especially interesting to see two photos of this age showing essentially the same moment in time. I hope I can find the source of the FB image.


Addendum: For those of you who have difficulty visualizing perspective, here’s a drawing that might clarify my conclusion.

Function of Pupillary Dilation in Sympathetic Arousal

A commonly cited response to sympathetic arousal is pupillary dilation: the eye’s pupils open up. Italian women of the Renaissance thought that by applying atropine (belladonna, literally beautiful lady) to their eyes, causing pupillary dilation, they could enhance their beauty, and modern studies by psychologists have shown that they were right: photographs of people with large pupils are judged to be more attractive than photos with small pupils (presumably because when you look at a person with large pupils you are looking at someone who is aroused while looking back at you). Psychologists have attempted to use pupillometry as a measure of emotion.

Dilated pupil (from Nutschig at the English language Wikipedia)

Constricted pupil (public domain)

What is almost always glossed over is the function served by dilated pupils in times of high emotional arousal.  One often sees statements such as “The pupils dilate, letting in more light so you can see better,” but this has never made much sense to me; why would making the scene brighter than normal make vision better?

I think I know what those dilated pupils are doing for us. At this point consider it a strong hunch, guided by years of thinking about both the adaptive value of behavior and about photography.  In photography, the term “depth-of-field” (DoF) refers to the region from the closest to the farthest part of the photo that appears to be in focus.  A large DoF means that objects near and far are in focus; landscape photographers typically want large DoF.  A small DoF means only a narrow region at a particular distance from the camera appears in focus and the rest is blurry; portrait photographers usually want small DoF resulting in a blurry background that does not distract from the model’s face. Enlarging the aperture of the lens decreases the depth-of-field, and reducing the aperture increases the depth-of-field.

Depth of field illustration. larger aperture on the left, small aperture on the right. (photo by Alex1ruff, licensed under the Creative Commons Attribution-Share Alike 4.0 International license)

Why should sympathetic arousal be associated with a large-aperture pupil and thus a small DoF? Wouldn’t you want a large DoF, with as much as possible in the scene in clear focus? I argue that no, in times of “fight or flight” a small DoF is beneficial. Accurate movement is essential, and judging the distance of objects (the branch to which you must jump to escape; the neck of the predator you have to bite to disable it) is critical. One unconscious cue that we use to judge distance is the extent that the lens must be curved or straightened to bring an object into focus — a process called accommodation. With a large DoF (small aperture pupil) there is a lot of leeway or “slop” in how accurately the lens must be curved. As the DoF gets smaller (with a large aperture pupil) lens curvature is more critical to focus as their is less slop. The result of that dilated pupil with its small DoF is more precision in the information that is provided by the lens accommodation; the brain therefore more accurately interprets the distance of the object being viewed. Behavior is then more accurate. Our arboreal primate ancestor escaping from the proto-leopard gauges the distance to the neighboring branch correctly because his pupils were dilated and he survives; his friend lacking the pupillary dilation misses the branch, and his genes are gone from the gene pool. 

To examine human DoF for constricted and dilated pupils, I used a web-based DoF simulator designed for photographers, applying photographic parameters to the human eye.  A web search suggested that a commonly-suggested value for the focal length of the human eye is 22 mm (the DoF simulator needs the entered focal length to be stated as if the camera in use is a 35-mm film camera, with film size of 24 x 36 mm; at least one online site suggests that in these terms the human eye’s focal length should be entered as 32 mm).  Another site suggests that the aperture of the human eye, expressed in the traditional f-stop terminology of photography, ranges from f/8.3 when constricted to f/2.1 when dilated. 

Taken from the online tool DOF Simulator, the grey regions illustrate the distance from the human eye that will appear in focus (depth of field) when an object is 3 m away. On the left – the DoF when the pupil is constricted; on the right – the DoF when the pupil is dilated.

The images (clipped from my session with the online DoF simulator) show the DoF when the pupil is constricted compared to the DoF when the pupil is dilated. Here the model is 3 m from the camera, a reasonable distance for that escape branch. With a constricted pupil (left), the area from ~0.8 m in front of that branch to ~1.6 m beyond the branch appears in sharp focus, a distance of 2.4 m. With a dilated pupil (right), the clear focus ranges from ~0.25 m in front to ~0.25 m beyond the branch, only 0.5 m. Clearly the dilated pupils provide better information about exactly how far to leap.

Please recognize that the values used in the calculations that created these estimates were at best rough approximations of the parameters of the human eye. However, whatever values are used, the dilated pupil will produce a DoF that is much narrower than that afforded by the constricted pupil, so the dilated pupil will always provide better information about the accurate distance to the object. 

[If someone wants to take this idea and develop it more fully or more rigorously please do so – just acknowledge my contribution, please.]

Thoughts on the Fate of Liberal Arts Colleges

Green Mountain College

Green Mountain College (VT) announced recently that it will close at the end of this year. Other small liberal arts colleges (LACs) face severe financial issues that have led to closing (Newbury College, Atlantic Union College, Mount Ida College) or fear of imminent closure (Hampshire College, Bennett College). Antioch College closed its main campus in Ohio a few years ago, and is now trying to rise phoenix-like from its ashes. 

I recall in the early 2000s seeing a TV segment about Upsala College, a small liberal arts college in East Orange, NJ, that had closed in 1995. The TV show featured an architectural salvage crew entering the now-overgrown buildings to reclaim whatever might be useful. My thought at the time was “Wow! How could that happen!? Glad it wouldn’t happen to me!”
 
Now it is clear that Upsala’s fate will be the fate of many other good schools. Why is this happening? All of these colleges have struggled with attracting students, whose tuition dollars are essential given relatively low endowments. Students chose not to attend these schools because of the perception that they could get the same education for a lower price elsewhere, typically at large state universities. This is a misperception that liberal arts colleges must overcome in order to survive
 
Course names and major names might be the same, but that’s where the similarities between the LACs and the state universities end. LACs send proportionately far more students to graduate programs than do the large universities; students come out of the small schools prepared for PhD programs because they have often done things that graduate students do: overseen research projects, presented papers at conferences, published articles. LAC graduates are preferred by businesses because they are better trained to think and to communicate.
 
High school students can’t assess the differences,and their parents are typically also not prepared to do so. A prospective student interested in, say, Psychology, will see a Psych program at Albion College and a Psych program at Big State, and on paper the programs look similar. Big State probably offers more courses, has a larger faculty, and publishes more papers, so Big State must be the better place. Look a bit deeper and the differences become clear: Big State has classes of 100 students or more, taught by graduate students, and those many research papers represent work done by graduate students under the mentorship of professors. Small classes at Albion are taught by professors, who oversee the research of undergraduates (much like the prospective student), mentoring it through to presentation or publication.
 
The prospective student who opts for the LAC will graduate in four years with a level of preparation that surpasses Big State’s graduates (who might have taken five or more years to graduate). Liberal arts colleges must figure out how to convey this truth to the prospective student and her parents if they hope to survive. I don’t know how to do this, nor, sadly, do most of the rest of us at liberal arts colleges. Until we figure this out the distinctly American liberal arts education is threatened, and with it one of the foundations of our country’s greatness.
 
News of the closings of these small schools saddens me, but it also reduces any potential regrets about my approaching retirement; I won’t have to spend much time worrying about the future of my job security at my very good small liberal arts college.
 
=========================
A few disclaimers:
 
Of course there are students who do very well at Big State U. My two older kids attended Big States and are quite successful in their careers. Finding and taking advantage of the best opportunities is easier at the LAC.
 
The perceived price difference between the LACs and Big State is smaller than it seems. LACs offer scholarships and financial aid that can significantly reduce the cost. The likelihood of needing more than four years to finish at Big State (due to difficulty in getting the required courses, or finding that the general education requirements for a changed major differ from those of the old major, requiring more classes, or maybe just due to poor advising) adds to the cost; LACs almost always get students out in four years.
 
This piece clearly reflects the views of the author, informed by many years of teaching at a liberal arts college, and experience at a few Big States.

Musings on Photography at Concerts

I have attended many events where the venue bars cameras. Typically this means “good” cameras, often but not always defined as cameras with interchangeable lenses. Most recently I saw Jesse Cook at the Kalamazoo State Theatre—it was a great show by fabulously talented musicians—and I watched as countless cell phones were used to take photos and to record audio and video. I had smuggled in my “good” camera, an Olympus OM-D E-M10, with a 45mm f/1.8 lens – a fast and somewhat short telephoto lens. Patrons were searched as the entered the venue; we had to have our coats open and security patted us down – probably checking for alcohol or weapons. My camera, in the pocket of the coat and thus held away from me as I opened the coat for inspection, was undetected.

Jesse Cook at the Kalamazoo State Theatre

My seat at the front of the Mezzanine (lower balcony) gave me a great view of the stage, and after the first song I got my camera out and took a few photos, being sure to hold this threatening object in my lap when not in use so that the watchful eyes of the security guards wouldn’t see it.  At a prior concert at this venue I had seen security approach people with “good” cameras and ask them to put them away under threat of expulsion (of course while cell phones were in use all around them); at that concert I had used a longer lens and got some great shots.  

So, should cameras be allowed or not? My view, not surprisingly, is that if photography is permitted, then the venue should not care what equipment is used, within limits. Equipment that could interfere with the enjoyment of the event by those around you should of course not be used – no flash, no tripods that might impede safe egress, no long lenses poking over the shoulder of the patron in the seat in front of you.  Once photography is allowed and phones are recording photos and video, cameras should not be banned.

Upon arriving home, I reviewed my shots and posted a few good ones to a Facebook album. By the next morning, the Kalamazoo State Theatre had “liked” my album. Here’s the reply that I posted to them:

Great show – glad you brought Jesse Cook and his other talented musicians to town! And I’m glad that you liked the photo album that I shared. I wish I hadn’t had to smuggle in my camera to take a few photos, especially considering that photos were allowed and there were many phones recording not only still photos but audio and video as well. Guess I need to add a phone app to my camera, then there would be no issue 🙂. Wish you would reconsider your camera policy.

No reply from them yet – I’ll post it here if they respond.

WordPress Themes