Field of Science

The Scoop on Thawing

My mom made delicious home-made ice cream. When I was a kid, she made it in a turquoise electric crank machine, the ice had to be chopped up with an ice pick and added, along with layers of rock salt to the bucket. The machine needed careful tending as the motor whirred away, a hot job on what was sure to be a hot day, but the reward for layering in the salt and ice was to lick the paddle.

Stephen Metcalf has a review of the next generation of ice cream makers up at Slate magazine: The Inside Scoop The next generation includes those with built-in freezers and and some with a gel filled canister you pre-freeze -- they still make the ones like my mother used and ones you can use at a picnic to soak up excess kid energy. Metcalf notes that

"More expensive machines contain built-in freezers, with obvious advantages: A built-in compressor maintains a constantly low temperature throughout the freezing process (whereas a gel canister starts to thaw the instant you remove it from your freezer), and consecutive batches can be made without waiting 24 hours for the canister to re-freeze."

There is physical chemistry here -- even though the gel canister does begin to thaw as soon as you take it out of the freezer, it doesn't actually get warmer immediately. As the gel thaws, the temperature remains constant until the thawing is complete. Why? A very simple-minded way of thinking about it, is that all the energy going into the canister goes into melting the gel, so there isn't any "left-over" to raise the temperature. Don't believe me? Take a glass of water and ice and stick a thermometer in it. Wait a while, stir (the stirring is important), and take it again. If all the ice hasn't melted yet, the temp should be unchanged.

A wonderful recipe for ice cream made with liquid nitrogen.

Another post on the physical chemistry of ice cream.

Weird Words of Science 6: adiabatic

adiabatic Describes a process in which no heat is gained or lost by the system. Comes from the Greek for not (α) through δια) passable (βατωσ). In other words, the heat doesn't pass through. The terms seems to have been coined by William Rankine in 1859.

Decode this one, coined in the 18th century? adiapneustia

Dispatches from the Frontiers of Science

This week I'm at a Gordon Research Conference (on Chemical Education Research and Practice). These are small conferences, meant to foster informal conversations between active scientists. They were founded 75 years ago by Neil Gordon, a chemist from Johns Hopkins. The ground rules for the conference are that no results may be cited from the conference, (so I can't post about the intriguing work I'm hearing about research in science education this week) so that presenters are encouraged to bring new, speculative, unfinished ideas to the table for active discussion.

I've heard Nobel laureates talk about current work, and sketch out their current thinking on unfinished problems, a rare and wonderful opportunity. Once, I'll admit, I heard a talk from a prominent scientist that repeated work of 15 years before, but generally the talks are interesting, if not all quite at the frontiers of science as Neil Gordon imagined them.

The summer conferences are held in New England at colleges and boarding schools. You stay in the dorms, eat in the cafeteria and have afternoons free to take a hike with colleagues and talk science. I have a friend who calls it summer camp for chemists!

Romancing the Stone

Summer reading should be fun, and not science, but the mystery/romance novel I picked up to read at the swimming pool had a great physical chemistry twist in it. The Paid Companion by Amanda Quick is set in the 19th century and features an evil scientist who believes himself to be the next Newton, working to build a weapon that could destroy London. The penultimate scene finds the heroine in the fiend's underground laboratory, where he shows her the device he has built from 3 red stones (it's implied that they are rubies) and an electrical source. The device produces a thin red beam that chars everything in its path -- what could this be? A laser, perhaps? The word never appears, but those in the know, what else could it be? Physical chemistry is everywhere!

Last year my physical chem students and I tried to build a laser (a dye laser, not a ruby laser) from scratch, and I now have a much greater appreciation for what it takes to get a working system. Interested in building your own laser in your basement? Directions can be found at Sam's Lasers

Flip-flops and MIPmaps

Computer speeds are measured in flops and mips. A flop (or flops, more precisely) is a floating point operation per second. These days, teraflop machines define fast (tera = 1012), while gigaflop (109)machines can be toted in a briefcase. A mips is a million instructions per second. Both flops and mips are difficult to compare between machines, since both depend on the instruction set used. Better to do a benchmark using something like LINPACK and compare times.

MIPmaps are an entirely different animal. The MIP part of the name is an acronym for the Latin multum in parvo or "much in a small space". MIPmaps are collections of pre-calculated chunks of an image that can be used to speed its rendering at different resolutions (say as you move closer to an object in a game). MIP is sometimes used as a shorthand for MIPmap.

Floating point numbers are like sand, everytime you move one, you lose a little sand and pick up a little dirt.

Build your own supercomputer

I'm enough of a geek to remember the excitement of running my first job on a supercomputer (in 1984 on a Cray X-MP). That machine ran at about 200 megaflops (floating point operations pers second) -- the laptop I'm typing on now is significantly faster. The present generation of supercomputers maxes out in the teraflop range, the current #1 machine is the Earth Simulator in Japan which clocks in at 35 teraflops!

Building and maintaining a supercomputer is an expensive business. There are some cheaper alternatives, such as beowulf clusters and grid computing, that let you spread problems out over a number of machines linked either by cables (the beowulfs) or over a network (grid). SETI@home is probably the most famous grid computing effort. Both methods require some kind of investment in a permanent infrastructure - what if you just wanted a supercomputer for day or two? You could ask for time on at one of the centers, or you could invite some friends with laptops over for pizza and build your own!

The FlashMob team has developed software that lets you link whatever computers you have lying around the house into an ad hoc cluster, run your huge computational problem, then unlink, have dessert and send everyone home. Download the software and give it a try!

The ACS Computers in Chemistry Division (I'm a past chair) and the Philadelphia section of the ACS are hosting an instant supercomputer event September 15 at Bryn Mawr. If you're in the Philly area and interested in computational chemistry, supercomputers, or just want to be able to say that your laptops was once part of a supercomputer, join us! More details coming later in the summer.

The "Productivity Puzzle" and the "Impact Enigma"

Remarks as part of a panel presentation on women in science, prompted by Larry Summers' remarks on the paucity of women in science for a joint meeting of the Cosmopolitan Club and the Franklin Inn club in Philadelphia.

I will confess to a guilty pleasure, I keep a blog. It's called the Culture of Chemistry, and for the most part it is a gentle riff on popular culture through the eyes of a chemist. Last week I posted a short piece called "The Hidden Women of Science" -- and overnight the number of readers quadrupled. The post was prompted by an article in the Chronicle of Higher Education about the record number of women elected to the National Academy of Science this year and reads in part:

"The words "women in science" tend to bring up the image of Marie Curie, Dorothy Hodgkin or, in a peevish moment, Larry Summers. These are not the women in science I'm thinking about. It's the hidden women, the women behind the scenes that fascinate me. The truly invisible women of science are the wives of the scientists who make it possible for them to work 80+ hours per week and still play golf.

A recent look at Princeton's cadre of science faculty, which is reasonably representative, one might presume, of the larger cohort of top research universities, reveals that the majority of male faculty enjoy a stay at home spouse. None of the female science faculty are so blessed. So what? So, the guys with spouses who work at home have staff. Someone to coordinate the school activities, the after school activities, the errands, the house repairs (who stays home for the plumber, eh?), the grocery shopping, car repairs, cooking, cleaning.....

So when we think about women in science, we must realize that much of the top-ranked academic research enterprise depends very heaviliy on the unpaid [and unacknowledged] labor of women -- in science."

The post provoked various comments on my blog and the blogs of others, by both men and women. One male computer scientist frankly acknowledged that his wife's willingness to take on these tasks made it possible for him to spend the hours necessary; a male English professor notes that he does the same so that his wife can make partner in her law firm, and that reading my commentary he realized that he was a "man of the law" in the same way; a woman computer scientist wondered why (with respect to Harvard): "there isn't really even an awareness that they might need changing. It is still a case of 'how can we make you more like us?', rather than 'women, what do you need so that you can strike a balance?'"

I'd reframe Nandini Pandya's comment and ask, what do we - men and women both - need to be successful, productive and well-balanced scientists without recourse to the hidden women of science (or the missing men of law!).

A couple of years ago I gave a paper at a international conference. There had been an after-dinner talk - the first given by a woman at this meeting in its 30-year history. Afterward, a clump of chemists lingered by the elevators, dissecting the talk, when suddenly an older colleague blurted out that science was, he thought, "a grim life for a young woman." He went on to say that you could neither do enough science to be taken seriously, nor take adequate care of your children, so it is rather a lot of drudge work, without any chance of reward. I certainly had not found my life to be "grim" at all. I enjoyed what I did as a chemist and as a parent. I am a successful scientist - tenured, promoted, on a list of highly cited scientists - and had managed much of this while raising two young sons who seem to be turning out reasonably well. (My kids read about this in an essay published this month and my youngest was aghast that anyone would think that a scientist could not be a great Mom - who else has a mom that can help you extract DNA in your own kitchen). Let's just say that my adversary's response, "Well, la-di-da for you!" did not exactly encourage further serious discourse on the issue. I hate to say it, but he does have a point: and one that is supported by research.

The National Survey of Faculty, based at Penn State, compared men and women in the fields of chemistry and English, noting that in both fields at any rank, at any type of institution, women faculty are less likely then men to be married or in committed relationships. The average number of children per woman faculty member is also substantially lower - again regardless of discipline, rank, or type of institution. The survey's authors attribute this directly to "bias avoidance behaviors" in women. Research has shown that time = papers, i.e. productivity (as measured by number of publicationss) is strongly correlated to the number of hours invested in research [M.R. Nakhaie "Gender differences in publication among university professors in Canada" Canadia Rev of Sociology and Anthropology 39 (2): 151-179 May 2002].
Restricting the hours restricts the output, and research shows that what we think is true - is in fact true: restricting the output reduces the chances for promotion. [J.S. Long, P.D. Allison, R. McGinnis, "Rank Advancement In Academic Careers - Sex-Differences And The Effects Of Productivity"] Women know that having a family will cost them, this is the "bias advoidance", both in terms of the hours of domestic work that their male peers not have to invest (men, on average, contribute 10 hours a week to a household, and adding children to the mix does not increase their contribution), and perhaps also in their reputation for academic seriousness. It is a Faustian bargain that women must strike—sacrifice your immortality for scholarly heft.

Scholarly heft is hard to quantify, and we often consider hours worked and papers published as the measure of the quality of the science. Hence Summer's comments that women aren't able or perhaps willing to work the 80+ hours needed. Are they needed? Well, certainly the research suggests they are needed to produce lots of papers. The "productivity puzzle" was proposed in an essay by Scott Long in the early 1990s: why aren't women scientists as productive as men? Recent research has shown that when you account for factors such as prestige of institution, marital status and effort invested (read time) there isn't a puzzle, the differences fade. Which suggests that inherently, women can be successful in science in the traditional way (publish lots of papers), as long as they have the time to invest.

The flip side of the productivity puzzle was the "impact enigma" - women's papers (in biochemistry, the field studied) are cited much more frequently. Why? Even given that the cohort of women studied were in more "marginal" positions, their research appears to be more valued by peers than men's. Is it that each paper must count for more, if you get one chocolate bar a year, it had better be Scharffen-Berger and not Hershey? The jury remains out on the reasons.

President Summers wanted to provoke a conversation, so I will respond in kind and ask two questions:

First, is a model in which depends on "hidden" contributions of women, sustainable in a cultural moment in which women are getting more of the bachelor's degrees than men? Is it fair to those, single parents, singles and women, who do not have access to the same support systems? And, in the end, is this system the most productive for society? My mother-in-law, an X-ray crystallographer, was married to another scientist, and faced productivity issues (a postcard found in her files congratulates her on a productive sabbatical, two sons and a new crystal structure solved). Mildred Dresselhaus, a highly productive and well-regarded materials scientist, at MIT is married to another scientist. If we took one of the two of the pair out of play in either of these partnerships, are we losing more than we are now (since presumably neither partner is as productive as they might be if each had a support staff)? Can we afford to lose 1/2 the pair, when we might have almost two? Certainly the answer to the last is no! To put it more provocatively, would some of Harvard's fifty million dollars be better spent creating a concierge service for faculty, than for more panel discussions?

Second, to what extent do we confuse quantity of publication with quality of work? Is the solution to the "impact enigma" to consider quantitatively the contribution of a scholar's work to the culture at large? If we made the shift to consider impact rather than sheer mass of publication, perhaps then the need for the heavy investment of hours would fade, the hidden women of science (and men of law) could go on to other things and the productivity puzzle would be solved as well!


  • Nandini Pandya has a wonderful essay on these issues being published this week. See her blog at Progressive Indian-American Woman
  • Christiane Nusslein-Volhard, who won the Nobel prize in Medicine in 1995, is well aware of this issue and is using her prize money to fund household help and childcare for women scientists in Germany. See Lisa Belkin in the NY Times 6/5/2005: "What a Working Woman Needs: A Wife". (Dr. Anna Meadows of CHOP pointed me to this article.)
  • Some of the material in here comes from an essay I wrote entitled "Elemental MoThEr" collected in Parenting and Professing: Balancing Family Work with an Academic Career (edited by Rachel Hile Bassett, Vanderbilt University Press, 2005) and published this month. Another short excerpt is posted here.

Weird Words of Science 5

secular If you look up secular in most dictionaries, the only definition given is "non-religious" or "of the world". Hunting a bit deeper yields an astronomical meaning, coming from Roman usage where a secular event is one that happens once in long period (such as century). [The Latin root is saeculum, "age".] Astronomers refer to long-period effects as "secular" effects. The secular effects in an orbit can be found by finding the roots of the secular determinant, which has the same form as the determinant that arises in quantum mechanics' linear variation theory. The physicists working on linear variation theory noticed the similarity in form and used the same term.

Elements of Trivia 1

How cultured is your chemistry? Test your knowledge!

What element takes its name from the Greek for lead? (Hint: It's not lead and was used in medieval illuminated manuscripts.)

The Topology of the Tangled Bank

The latest edition of the Tangled Bank is up at geomblog. The emphasis is on math and physics blogging, but there is plenty for biology fans as always.

Film Studies

In the late 19th century, Wilhelm Roentgen discovered the x-ray. X-rays are light, with very short wavelengths (on the order of 10s of Angstroms) relative to visible light (on the order of 1000s of Angstroms). Roentgen was experimenting with various materials to see what might be opaque to the new rays by placing samples in front of a barium platinocyanide screen which fluoresced on contact with x-rays. When putting a block of lead in the way, he noticed the skeletal image of his own hand on the screen. Roentgen published a paper less than 2 months later detailing his discoveries, but it turns out that the first x-ray image had actually been made two years before at the University of Pennsylvania, and filed away, its significance unrecognized by the researchers there.

The new rays were all the rage - as an article in McClure's magazine shows. Many of the images in the article were produced at the Urania in Berlin by Spies. The Urania was a scientific theater, where spectators paid to see new scientific discoveries (and other interesting phenomena) demonstrated and explained. The x-ray at the top of this post is of Professor Spies' wife's hand.

Science as performance -- a new funding model? Set up the lab, train a guide and sell tickets to the latest new discovery.

Why can't a woman be more like a man?

A post on Harvard's new $50M initiative for women in science by a woman in IT, brings to mind Henry Higgin's lament in "My Fair Lady": Why can't a woman be more like a man?

Progressive Indian-American Woman notes

. Seems to me they want to spend $50M to get more women and minorities in. But they are not really looking towards changing their system. Indeed there isn't really even an awareness that they might need changing. It is still a case of "how can we make you more like us?", rather than "women, what do you need so that you can strike a balance?"

On this coming Friday, I get a chance to speak on these issues at the Cosmopolitan Club in Philadelphia.

Glow in the Dark Kid

"Mom, is it OK for me to go back to school?," asks my 11-year old wounded road warrior. We're driving back after getting his shoulder x-rayed - he broke my tail light (and his pediatrician suspects, his clavicle) after hitting my car with his new bike.

"Sure you can go back to school, why not?" "I'm radioactive now, aren't I?" "Ah....well, actually you are, but not from the x-ray!"

Slate magazine's Explainer column last week looked at the radioactivity of everyday materials in "Is Cat Litter Really Radioactive?". (The short answer is yes.) People living in the US are exposed to roughly 360 millirems of radiation a year. Most of this is from naturally occurring sources, such as cosmic radiation and radon (and cat litter). About 10% of the exposure is from your own body, which contains measurable amounts of carbon-14 and potassium-40, both are which are radioactive. Your basic banana contains about 47 μg of potassium-40. Crash Kid's x-ray probably exposed him to less than 10 mrems, about what he gets every year from flying to visit his grandparents in California. To put this all in perspective, an acute dose of 50,000 mrem could give you radiation sickness.

Oh...the fracture is limited to the tail light!

Book Meme (from Snail's Tales)

Aydin tagged me last week, but I haven't had a chance to respond until now.

Number of books I own: The collection is hovering around 5000 volumes and I've committed to a "one in-(at least) one out" philosophy, so that is its size for the foreseeable future. There are no more walls to put bookshelves against - so unless we convert the kids' room to compact shelving (and don't think I haven't dreamed about it!)...this is it.

Last book I bought: Spirit of Fire by Ursula King. A biography of Teilhard de Chardin, a Jesuit paleontologist and theologian.

Last book I read for the first time: I wished I'd made you angry earlier. This series of essays by Max Perutz, a Nobel prize winning x-ray crystallographer is wonderful to dip into. I didn't read them in order, but opened it up at random to find yet another gem. There is an essay about Haber, Germany and the war effort, and another one about the discovery of the α-helix.

Four books that have influenced me:
Lady with a Spear by Eugenie Clark. Women in science, working your way through school, and adventures in the Pacific, this book has it all. Dr. Clark's sheer joy in the science comes through, and even though I didn't end up as an oceanographer, I think I take as much pleasure in my work as she does in hers.
The Seven Storey Mountain by Thomas Merton. The courage to change your life, or let it be changed in dramatic and sometimes, difficult ways. The book that inspired me to begin praying the Liturgy of the Hours on a regular basis.
The Liturgy of Hours
Marie Curie by Eve Curie. When I was younger, it was such a romantic tale -- fainting in a garret, so entranced by the science that she didn't eat (or couldn't afford to!) ; meeting her husband, another scientist. When I was older, coping with being a young widow...

Five bloggers to tag:
Respectful Insolence
The Examining Room of Dr. Charles
Geeky Mom
See Jane Compute

I cross posted this on my other blog (Quantum Theology).

The Hidden Women of Science

The Chronicle of Higher Education has an article this week on the election of a record number of women to the National Academy of Science, the obstacles women face, and a forum on issues related to women in science. The words "women in science" tend to bring up the image of Marie Curie, Dorothy Hodgkins or, in a peevish moment, Larry Summers. These are not the women in science I'm thinking about. It's the hidden women, the women behind the scenes that fascinate me. The truly hidden women of science are the wives of the scientists who make it possible for them to work 80+ hours per week and still play golf.

A recent look at Princeton's cadre of science faculty, which is reasonably representative, one might presume of the larger cohort of top research universities, reveals that the majority of male faculty enjoy a stay at home spouse. None of the female science faculty are so blessed. On the face of it, this is not surprising, since the bulk of women with doctoral degrees are married to highly educated spouses. In these days, men (highly educated or not) do not frequently choose to stay out of the job market and work in the home. Women have more freedom to make such choices in the current social millieu. So what? So, the guys with spouses who work at home have staff. Someone to coordinate the school activities, the after school activities, the errands, the house repairs (who stays home for the plumber, eh?), the grocery shopping, car repairs, cooking, cleaning. Yes? In households where both work, say as science and math faculty, someone still must do those chores! And these things do take time. Outsourcing is expensive, particularly for younger faculty, and in some cases just not easily accomplished. (Again, who stays home for that plumber? Our toilet was stopped up for a week until one of our schedules was open enough to allow for someone to be here for the extended period of time required. I was trying to submit a paper, and my session timed out twice while I was trying to help the plumber identify the object that was stuck in the @#$% thing.)

So when we think about women in science, we must realize that much of the top-ranked academic research enterprise depends very heaviliy on the unpaid labor of women -- in science.

The French Connection: Napoleon and Laplace

The Laplacian is a scalar (not a vector) differential operator that appears in important equations in physics and chemistry, such as Schrodinger's wave equation.

The operator, and the quintessential equation it appears in are named for Pierre-Simon Laplace, an 18th century French mathematician, who made critical contributions to the development of calculus and classical mechanics. The Laplace equation
appears in Laplace's Treatise on Celestial Mechanics, however, it was not original to Laplace, having been known for almost a half century.

Chemists typically write the Laplacian using the symbol ∇, however, some mathematicians will use Δ instead. Since chemists associate Δ with "change in" or "heat", depending on context, the source of the preference is obvious! The Laplacian can be constructed for higher dimensional spaces. The symbol used for the operator in 4-dimensions (called the d'Alembertia after another French mathematician of the 18th century, the quarrelsome Jean Le Rond d'Alembert) is . I presume the symbol for the Laplacian in 5-D would involve a pentagon?

What do Laplace and d'Alembert have to do with Napoleon Bonaparte? Laplace was appointed by Napoleon to the Ministry of the Interior, but removed from his post in less than a year for what Napoleon later wrote was his habit of bringing "the spirit of the infinitely small into the government." Napoleon was 14 when d'Alembert died, as far as I know, there is no direct connection.