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How Does a Scanning Electron Microscope (SEM) Work?

admin August 28th, 2009

Flip on the light in your kitchen and take a look around. In front of you most likely are your cabinets, refrigerator, and maybe the trusty coffee pot that you stumble downstairs to turn on every morning. We process the world through sight so naturally that rarely do we think about how it occurs, but the truth is that we do not actually observe the objects around us. Instead what we really see is the pattern of light that bounces off of them. The reason the coffee pot looks different from the fridge is that the light interacts with it differently, sending different patterns to your eye. If you find this difficult to believe, flip that light back off again. To your eye, your kitchen has vanished. The coffee pot still exists, but now there is no light to bounce off of it.

Electron microscopes work much the same way, but instead of bouncing light off of an object to figure out what it looks like, they use electrons. Why use electrons? Well, because they are smaller than photons (light “particles”) and like smaller pixels on a TV, they provide a more detailed picture of the thing you want to see. Imagine that you are blindfolded and given a small object (say a toy car) to draw and identify. At first, you are only allowed to feel the object with your arms. Later, you are allowed to hold and feel the toy with your fingers. Your fingers give you a much better description of the car because they are smaller, and can fit into all the small folds and crevices. Your two drawings will look very different. The same principle works for microscopy. The smaller the bits exploring the object, the more detail we can observe.

While light microscopes use glass lenses to focus light down on an object, electron microscopes use magnetic lenses to focus down the electrons. Electrons are scanned over the object, and information about how they interact is sent back to sensors. The sensors then use this information, just like your eye, to create an image of what the object looks like. As you can see above, SEMs can produce very highly detailed images of small objects, achieving up to 250 times the magnification of light microscopes.

Of course this is a very simple description of a complex technology. Yet strip away the details, and underneath it all is the simple idea that you’ll figure out more about an object by poking it with a pin than you will with a bowling ball.

Funding Affects Creativity in Science

admin February 11th, 2009

Today, I would like to bring your attention to a well written and very true op-ed from the New York Times.

http://judson.blogs.nytimes.com/2009/02/10/guest-column-letting-scientists-off-the-leash/?ref=science

“It’s almost like a small business — each faculty member is essentially running an enterprise for which he or she must find revenue (grants), manage finances, balance the books and pay expenses like salaries, tuition, rent and even taxes to the university for the space used.

Such a system does not come without its own perils. It is not so easy to ask our young scientists to think out of the box when a significant portion of their salary (and mortgage payments) depends on guaranteeing a steady source of funding. Consequently, professors become highly attuned to the institutional priorities of various funding agencies — often at a cost to their own creativity and desired research direction”

Today

admin December 15th, 2008

Today I

1. Somehow allowed my son to smack his head on our vessel sink. A call to the nurse confirms he is OK, but I still feel like an inept mother

2. Almost started a grease fire. Turns out once you are heating up the oil, you shouldn’t allow yourself to get distracted. It was the kiddo fussing and staring at the smoke who alerted me to the danger.

Let’s hear it for tomorrow!

I totally agree with this

admin November 10th, 2008

True, even in the hard sciences and engineering. This article is copied from Science Magazine online Career section.

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Issues & Perspectives
Taken for Granted: Joe the Plumber and the Postdocs

By Beryl Lieff Benderly

November 07, 2008

Supervisors have largely abandoned any pretence of promising a career, except to the handful of star students usually designated early by mega-prestigious awards and publications.

Joe the Plumber, John McCain’s favorite working man, might not have turned out to be the perfect symbol of Americans’ struggle to get ahead in hard times that the Republican presidential candidate originally imagined. But McCain was on to something, nonetheless. Even if the real-life Samuel Joseph Wurzelbacher is not in fact a licensed plumber , the plumbing trade still has something important to teach us about how opportunity works in America. It’s a lesson, surprisingly enough, that is particularly relevant to a seemingly quite different group of workers who have been facing tough times not just for weeks–but for decades: the nation’s postdocs.

Over the past 35 years or so, the labor market that postdocs work in has undergone drastic, painful, long-term change. Among the high-profile indications of that transformation are the recent decisions by postdocs across the University of California system, and at McMaster University and the University of Western Ontario in Canada, to follow the earlier example of their counterparts at the University of Connecticut Health Center and form labor unions.

Of course, the idea of belonging to a union is nothing new on America’s campuses. Back in the days before the big change happened–say, during the middle Pleistocene when I was in graduate school–people used to jocularly call the Ph.D. a “union card.” No one says that much anymore, even as thousands of scientists who hold such degrees have decided to carry an entirely different kind of union card.

To understand what this means and what it has to do with plumbing, think back to high school American history and recall that historically there have been two quite different types of labor unions, each designed to serve workers in a particular kind of labor market. One type is the so-called trade or craft union still prevalent among skilled workers in the building trades, such as carpenters, electricians, and, of course, those wrench-wielding mavens of drains.
Crafting protections
Beryl Lieff Benderly

The craft union model descends from the medieval craft guilds that once protected the prerogatives and incomes of high-level artisans by controlling who could legally practice particular trades. Like those guildsmen of yore, skilled members of today’s building trades often hire themselves out as contractors on a variety of temporary jobs and thus need protection from competition. Therefore, the major functions of their unions, apart from working to establish the going rate for their labor, are guarding the standards for practicing the craft and maintaining firm boundaries to keep outsiders from competing with union members.

Craft unions do this in part by overseeing the training and credentialing of aspirants to the trade and, through union-run hiring halls open only to members, by controlling who gets the union jobs that, of course, pay the best wages. These privileges, naturally, accrue only to holders of hard-to-get and therefore often highly coveted union cards.

In former times, the Ph.D. functioned in precisely this manner. It admitted newcomers to the privileged ranks of a professorial guild and protected full-fledged faculty members against interlopers trying to snag tenure-worthy posts with lesser degrees. Philosophiae doctor literally means “teacher of philosophy,” and teaching–or, at least, joining a university faculty–was what people who earned the degree overwhelmingly wanted and expected to do.

Of course, the basic goal of any self-respecting craft union (and of similar professional groups such as physicians) is limiting the number of apprentices who can enter the trade and eventually compete with the established members. If a union can enforce those boundaries, it can also provide another truly major benefit: sufficient work at attractive wages. Apprentice plumbers and electricians (and medical residents) agree to accept a trainee’s income while working hard and passing required exams. But once they progress to the status of journeyman or master craftsman (or board-certified specialist), they are pretty much assured a chance at earning a decent (and for master craftsmen and specialist doctors, a good-to-amazingly excellent) living practicing their craft.
A broken agreement

The same used to be true also in academe (except, of course, for the stratospheric earnings, which academics gladly traded for their exceptional lifestyles). In decades gone by, what labor economists Paula Stephan and Sharon Levin have called an “implicit contract” existed between professors and their graduate students (and the tiny handful of postdocs). It was the very same agreement that craft unions still make with their apprentices. A young person works at puny trainee wages for a time while meeting or exceeding the standards for entry into the trade. A mentor or guild then arranges opportunities for the successful novice to launch a career.

In the old days, professors considered finding jobs for their students a moral responsibility. And, as French management professor Vincent Mangematin has pointed out , the arrangement just happened to also help senior academics advance their own careers; the eminence of their students’ positions and accomplishments redounded to the mentors’ reputations. Not coincidentally, the system also encouraged professors to recruit only the number of grad students they could reasonably expect to place in suitable posts, thereby maintaining those reputations.

By the 1970s, however, the old compact was breaking down, and observers of the scientific establishment were beginning to worry aloud about training more Ph.D.s than could find appropriate faculty jobs. But the elders of the professorial trade, unlike the plumbers and the doctors, ultimately let down their side of the bargain. There grew up within the funding research system what Michael Teitelbaum of the Alfred P. Sloan Foundation calls “perverse” incentives that instead encourage principal investigators (PIs) to take on as many grad students and postdocs as they possibly can.

Unlike the master artisans who diligently guard the value of their union membership, the professors who run federally funded labs gave up limiting their students and trainees to the number they could successfully launch. Instead, they came to view students not as future guild members but rather mostly as cheap labor useful for doing the work needed to get and keep grants. Instead of the old contract between master and apprentice, graduate training these days, in Stephan’s stinging words, “resembles a pyramid scheme.”

But most professors no longer worry because they know that the majority of those aspirants will never become competitors. Professors’ own reputations among their peers now depend much less on the fate of their students and trainees than on their ability to win grants. The professoriate’s de facto union card is no longer the Ph.D. but the first tenure-track appointment–the launching pad for the grants competition–or perhaps even the first competitive federal grant.
Grave new world

Few among the mass of grad students and postdocs, however, will ever enter that ultra-elite guild no matter how many hours they toil at their PI’s bench, because there simply are too few academic jobs. Supervisors have largely abandoned any pretence of promising a career, except to the handful of star students usually designated early by mega-prestigious awards and publications. Few professors, in fact, even have the contacts or knowledge to steer young people toward the jobs that do exist, in quite substantial numbers, outside the academy.

As Mangematin has shown, the criterion that marks success in academe and that professors urge students to attain–publications in leading journals–carries far less weight on the outside, where most grad students and postdocs ultimately spend their careers. And though a study by Harvard University economist Richard Freeman and colleagues found grad students and postdocs very dissatisfied with the current state of affairs, many of their professors agree with one who stated, “I don’t find a whole lot wrong with the system. … It’s not broken.”

That leaves grad students and postdocs not as promising aspirants to a prestigious trade but rather as employees of large organizations, namely, the research universities that pay their wages out of PI grants. As such, these young scientists are exactly the sort of worker for whom the second type of labor union, the so-called industrial union, was devised. This type serves the interests not of accomplished artisans selling their skills in competitive markets but rather of workers drawing their pay from a given large company or organization. Rather than defending the prerogatives of a particular craft against the threat of interlopers, industrial unions strive to recruit all the workers at a particular workplace and defend them against the power of their employer.

The unmistakable transformation of aspiring scientists from apprentices to hired hands has finally persuaded at least some postdocs to move explicitly from the now-outdated trade union model of academe, with a “union card” that no longer opens the way to a desired career, toward an industrial union model designed for large numbers of employees who need to negotiate job conditions with their single, even larger, employer. The old “union card” no longer provides Joe and Joan the Ph.D. scientist decent employment in academe. Perhaps their new union cards can.

The thing is

admin November 4th, 2008

I love taking care of my son, and I’m not sure I’m ready to quit right now but…

This not having a job lined up is terrifying. I have never not been on a path to somewhere. This uncertainty is crippling.

So I plan to write something of real substance soon. Promise.

Are We Really Drips?

admin October 14th, 2008

Ask any woman who has left academic science for another career and you are sure to hear about her sense of guilt; guilt for “wasting” her training, guilt for not living up to expectations, guilt for becoming another negative point on the female academic census. Women who leave academia to go on to successful careers as businesswomen, lawyers, teachers, writers, and industrial researchers, to name a few, often still refer to themselves as “drips” in the academic pipeline. What is so incredible about these women is that this guilt remains regardless of the circumstances that led to their alternate careers. The term “drip” connotes someone who whether via insurmountable obstacles or some personal flaw could not maintain a steady path to the goal. What neither the word nor the statistics elucidate are the many women who could have become professors, but who make conscious and courageous decisions to jump off the academic path for their own reasons.

A trend is growing in the national workforce. Young professionals are no longer content to labor simply for wealth, promotion, and prestige. Workers want to enjoy their jobs. They want to work in pleasant environments with competent people, and they want balance. Corporations are acknowledging this trend and are offering flextime and other benefits in an effort to keep valuable employees who might otherwise leave to work at home or more accommodating offices. Young women are no different. No longer content to toil under several years of apprenticeship to eventually claim tenure and a professorial seat they may not enjoy, educated women are looking elsewhere, to places where they feel their work will be fulfilling and help achieve unique personal goals. Why do we still consider an academic career the best path for doctoral females? Why is any other career considered a drip?

Labeling women who leave academia to pursue careers they have deemed more favorable as “drips” does these pioneering scientists a disservice. These women are not failures. They are leaders. The goal should not be to attract as many women as possible into the academic ranks, but to ensure that all qualified females who want to achieve these positions are able. It is time we changed perspective by acknowledging these women, and distinguishing them from those who would have welcomed a professorial placement, yet were unable to achieve it. Certainly there still is much to accomplish in academia when it comes to attracting and promoting female scientists. We can start with making an effort to eliminate the guilt that academic culture places on women by indiscriminately labeling them “drips,” and acknowledge that the goal should be helping young female scientists find their own best careers, not blindly pumping them through the pipeline.

6 Things I miss

admin April 10th, 2008

1. Mr. Wizard.
He was SO AWESOME. Why can’t they play Mr. Wizard reruns? We have Andy Griffith, Momma’s Family, Scooby Doo and Little Miss Sunshine all running right now. Why not Mr. Wizard?

2. Naivete about the safety of vehicles.
After years of science and engineering classes and a few summers spent mopping up after things have gone wrong, planes (not really trains) and automobiles have become tools of death. Especially automobiles.

3. My grandparents.
You never fully appreciate them until they are gone and you realize your kids will never know who they were.

4. Summer break
How much I would enjoy three months to spend or waste in sunshine, in pools, selling koolaide, and making it back home for dinner before dark.

5. Having infinite career choices
What do I want to do when I grow up used to be a great game. Now it is serious. And the more choices you make, the fewer that are left in most cases. I just don’t really see me as a fighter pilot, or an Amazon explorer or a dictator any time soon.

6. Playing with the parachute.
Did anyone else do this in PE? That was so much fun. Even if I could buy one now, I just don’t think it would be the same.

The Thesis

admin March 26th, 2008

I am somewhat afraid of the thesis. Afraid I can’t get it done. Afraid it won’t let me leave. I have some confidence at the
moment, but I have to say that the thesis weighs on my mind.

Yesterday I added a HUGE amount to the thesis. It was mostly cutting and pasting from work I had done before. It is very rough and will need major editing and adding, but when I look at my document it now has a shitload of pages, and that makes me very happy. Maybe I can like, totally own this thesis.

The problem with me is that I love to write. This would normally seem more of a benefit than a problem, but the thing is I love to write well. I like to say things perfectly, beautifully, or at least the best I can muster, so previous writing was taking a long long time. I have decided that instead of something to look back on with glowing pride, I should just do this thing. I don’t mean that I shouldn’t worry about doing a good job, or getting things right, but I think I won’t try to make this a wonderful example of my writing ability, and more of a recap of what I have been doing and what I have learned in the last five years. And that I think will be good enough. I don’t love my research. I am ready to have it done. I need to finish this thesis.

I came across a wonderful analogy to the thesis writing process today on the blog of PhD (People have Doubts) so I thought I would re-post it here. Plus, I just have a thing for ants.

http://notarealdoctor.blogspot.com/2007/01/what-is-deal.html

“Monday, January 8, 2007
What is the deal?

Here is the deal. I am 28 years old. I have been in school since I was 4.
24 years of school. I have been in university since 1996. 11 f*cking years. The thought of that makes me want to pull my hair out.

The bright side? I am nearly there. NEARLY DONE.

The problem? There is one tiny weeny itsy bitsy little thing in my way. One minor task I need to complete so I can say good bye to school and enter the real world. I can’t even type it really. I haven’t said the word in weeks. Its just such a dirty sonofabitch of a word. Thhh thhhh. THESIS.

There I said it. I need to write my thesis. the-sis. thes-is. It’s just a thesis. Why is it so scary??? All I need to do is write it and I am free. I mean I can’t possibly fail my defense, right? Just write it, everyone keeps telling me. Just hurry up and finish. It sounds so easy.

No one really understands what a PhD truly entails unless they have gone through the process themselves. No one in my life (besides co-workers and fellow students that is) has any clue what is going on in my life, or in my head. They pretend to be sympathetic and say they feel for me but really, they can’t begin to understand how I feel right now.

How do I feel? I feel like an ant. Who left it’s family (herd? colony!) Who left it’s farm 5 years ago because it’s family was hungry and said ant thought to herself “Self, my family is hungry and they always think I am fat good for nothing ant but I am not good for nothing! I am smart and I have goals and I want to change the world!! I am going to prove to my family that I am Super-Ant!!” So Ant goes out into the world, away from the life she has lived in comfort in for her life and goes on with the goal to find the biggest piece of food ever known to man, I mean ants, and bring that huge delicious chuck of food back to show everyone in her farm that she is able and she, herself, is going to end ant-hunger.

After 5 years of the most excruciating journey of her life, after hundreds of sleepless nights, 18 hour days, begging for food, for love, wanting to bury herself in an abandoned ant-hole, Ant finds what she is looking for. Everyone is excited for her, but most of all they just want her to bring the damn thing home and get on with her life. All she has to do, they keep telling her, is bring it home. Just do it. But how is Ant going to get her prize home? It weighs 14million times as much as her! Its uphill all the way home!

I am at the bottom of the hill with this immense weight on my shoulders. All I have to do is bring it up the hill.

Easier said than done.”

The Crazy Belt

admin March 14th, 2008

I do not understand GA’s Governor Perdue. He has no problem with signing a bill that would allow a stadium to sell alcohol on Sundays, but will veto the bill if it contains an extra provision for general alcohol sales on Sunday.

In an article, Perdue is quoted as saying, “Six days is plenty” [to allow liquor sales in Georgia] “We need a little relief on Sunday.”

Relief from what? From the hoards of zombie-like booze crazed consumers beating down doors and demanding more vodka on Monday-Saturday? From the horrible soul-condemning sinning that is the purchase of wine and beer? From the roads clogged not by soccer Moms and commuters, but by those out to pick up their daily handle? Maybe Georgians should be spending so much time in church and with their families on Sunday that they just shouldn’t HAVE TIME to grab some half-price pre-mixed margaritas?

I just think it’s crazy how in a state where most everyone can tell you they’re confident they could score some illegal moonshine if they wanted it, Sunday alcohol sales are such a huge issue.

Human BPA contamination is confirmed by study

admin February 28th, 2008

I read this today in the peer-reviewed journal “Science”

“SHINY, PLASTIC PEOPLE
You may already be a part of Ken and Barbie’s plastic family. A new U.S. government study suggests that the bodies of most Americans are laced with bisphenol A (BPA), the primary component of one of the most widely used plastics.

BPA is an ingredient in polycarbonate plastics, used in everything from baby bottles to composite dental fillings to toy dolls. Frequent use and heating can cause the plastic to break down, leaching BPA into whatever the plastic touches, including food. Although recent studies have linked BPA to reproductive problems in lab animals, little is known about humans and BPA.

To measure BPA exposure, chemist Antonia Calafat and colleagues at the U.S. Centers for Disease Control and Prevention in Atlanta, Georgia, examined urine samples from 2517 participants in the ongoing National Health and Nutrition Examination Survey. Significant levels of BPA were present in 92% of the samples. Those with the highest levels were children and adolescents, women, and low-income participants.

The body metabolizes BPA in only a few hours, suggesting that exposure to BPA is continuous, says epidemiologist Russ Hauser of Harvard School of Public Health in Boston. Although the jury’s still out on what high exposures mean for human health, Hauser says industry should consider alternatives that aren’t biologically active.”

I had heard several mentions about BPA in the blogosphere, but I had wondered if this was perhaps a case of people becoming alarmed at something that was not truly of concern. Perhaps the amounts of this stuff were very small. Perhaps we weren’t really absorbing it. To my knowledge, previous studies have been conducted in animals, and while this information is very useful, animal models do not always correlate well with human biology. Well now they have found this stuff in people. It appears that this is a real phenomenon. Of course, as the article says, we don’t have a firm handle on what this means to human health, these findings are truly alarming.

If you would like to read some very thoughtful writing on this subject that includes information on how to remove BPA leaching products from your home, I highly recommend a post by Michelle at mihow.com.

http://mihow.com/articles/2008/1/28/waging-war-against-bisphenol-a

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