Sick Day

Laser Mom is taking a sick day.

One of the hardest things about being a parent, especially a stay-at-home breastfeeding one, is the lack of sick days. You are never completely ‘off duty.’ My daughter still wants to eat and play, to go for walks outside and be held. So I am going to take a break from blogging to rest and recuperate.

If you still need your fun Physics fix for the week, check out this website on the Scale of the Universe. It’s a great interactive website that let’s you see how big things are in comparison to one another – from cells to galaxies and beyond.

Or check out the latest Physics news from one of these sites:

Back to more Physics of babies in April…


Peer Reviewed Journal Articles

I usually work on my blog entries on Saturday mornings at a coffee shop so I can get away for a few hours and concentrate. I find it difficult to make much coherent progress on anything Physics related in the short periods of time I get during the day while my daughter naps (especially when she takes short naps like she has lately). At home, I am distracted by all the household work that needs to be done – bills to pay, laundry, dishes, and lately, unpacking.

This Saturday, however, I found myself having to do some other Physics related work. I find it interesting that despite the fact that I am not currently gainfully employed and have no official affiliation to any teaching or research institute, that I still have research work to do. I was asked to review a journal article for Optics Express, an open-access online journal published by the Optical Society of America. Doing a good review of a journal article takes a good amount of time and so I spent my Saturday morning working exclusively on this task.

So, instead of a blog entry on teaching or the Physics of babies, I thought you all might be interested in learning more about the peer review process – how are journal articles reviewed and published? I think this is particularly interesting in the world of constant information online from all sorts of reliable and unreliable sources. When teaching, I tried to help my students understand the importance of using peer-reviewed sources. While the system is certainly not perfect, these sources from good journals are much more reliable than news articles and other online sources written by non-experts.

Why do scientists bother to write these journal articles? Researchers are required to publish to show that they are doing ‘worthwhile’ research. It is generally a requirement to graduate with a PhD, get a research position, and get promoted. This applies mostly to academic institutions as private companies tend to want to keep their research private.

So how does this work? You do some research and get some cool results – you either build a new widget that you think has potential to change the world or measure something better than everyone else. Or, usually, something less impressive but still interesting. I have a couple of published journal papers on shining a laser beam into a photopolymer (plastic that is sensitive to light) and making the plastic change in interesting ways. Fun stuff.

Then you describe what you have done in enough detail that a reader could replicate your work. That is the goal at least, but with time and page limits, we all tend to leave out important details. You format the paper to the right page length, font, etc. for a specific journal and you send it to them and say, “I would like you to publish this in your super awesome journal.”

Next the editor looks at the paper and decides whether or not to even review it. If you send it to a very prestigious journal (Science and Nature are two), it may be rejected out of hand if it is not considered new and interesting enough.

If the editor decides the paper has some merit, s/he sends the paper to a set of reviewers, usually three different people. These reviewers are scientists who have published in that journal in the past and do work that is related to the content of the paper. I was reviewing a paper this past week for Optics Express because I have two past publications in that journal and the topic of the paper was related to photopolymers, which I have done research on in the past.

So I get this request to review the paper. Here comes one of the ‘not such a good system’ parts of the review process. The peer review process is constantly criticized for taking too long to review and publish new research. The online publications try to work faster. So I was given one week to review a paper. This is not a long time when you are home with a baby and do not have a lot of free time. It takes several hours for me to critically review a paper, and longer depending on the complexity and quality of the paper. This short turn around time can definitely result in a poor paper review.

But I agreed to do it and I did.  Reviewers are asked to consider the following questions (these are specifically for Optics Express but are similar for other journals):

  • Does the technical content merit publication in this journal?
  • Is this paper an original and significant contribution?
  • If it is not original, can you cite prior publications on the subject?
  • Are the results significant to the field and/or offer interdisciplinary application?
  • Are conclusions supported by the data presented?
  • Is the work placed in proper context?
  • Is related work adequately referenced?
  • Does work warrant publication in an archival journal?

There are several options for a review:

  1. Accept the paper with no changes. It’s awesome. Publish it as is. This is not common. I have never done this, but did have one paper that received this review. You sort of wonder if they read it when this is the response you get.
  2. Accept the paper with revisions. This comes in two forms:
    1. Minor revisions: I make suggestions for changes but consider them minor enough that I do not need to re-edit the paper. The journal editor is in charge of making sure those edits are made.
    2. Major revisions: I list things that need to be changed to make the paper publishable and request to re-edit before the paper is published.
  3. Reject outright. I have only done this twice. Once for a paper that was in such poorly written English that it was unreadable. And once for a paper whose authors ignored the reviewers comments (despite all three reviewers making the same comments).

Some examples of changes that might need to be done:

  • Clarify a point that is not clear.
  • Add or improve a figure or picture that is not clear.
  • Fix a mistake in an equation or calculation.
  • Describe in more detail why your research is interesting or relevant and why people might want to read your paper.
  • Add data when it does not seem that you have sufficient scientific data to back up your point.

Really, anything at all that would make the paper a better paper can be suggested. The idea is to hold the authors to a high standard of scientific research – you expect that their work is careful, well thought out and honest.

The editor takes the reviewers comments and sends them on to the author or edits them. If the reviews are wildly different, s/he might get another reviewer.

The reviewers do not get paid. I do not get anything at all except the right to put this on my resume as “service to my field of research.” It is expected that scientists take the time to review papers as carefully and thoughtfully as they would like their own work reviewed. The system is not perfect, but having at least three expert reviewers and an editor keeps things honest.

This is very different from the review process for most information online and I consider these journal articles to be a much more reliable source of information. Of course, most are so technical that only an expert in the field would understand them, so that’s not too useful. Like I said: The system is far from perfect.

Airport body scanners

I have been in the middle of a cross-country move the past few weeks, which has been quite challenging with a baby in tow. According to Google Maps, we moved 1423 miles from our old home to our new home. We also moved 4292 ft higher in elevation (according to Wikipedia). No wonder I am exhausted

For work reasons, we needed to move rather quickly. Normally, we would have driven, which takes about 24 hours. With stops for feeding, changing, and soothing a baby, that would have been at least 3 long days, or 4 or 5 if we took our time and stopped to see things on the way – after all, if you are going to drive more than 1400 miles, you might as well see the sights along the way. Unfortunately, we did not have time for that this trip, and so I flew with my daughter to our new home.

I am a relatively frequent flyer and adept at getting through security quickly and efficiently, though it is definitely more of a challenge now that I have a baby with me. I, like all of you who fly I’m sure, have noticed the increasing number of airport body scanners in the security line over the past couple of years. My first experience with one was returning to the US from an international flight in the spring of 2010. Now they seem to be in all the airports that I frequently fly through.

There are a number of issues surrounding these scanners: privacy, effectiveness, cost, and safety. There are huge numbers of articles around the web on each of these issues. I started to think seriously about the last one – safety – last year when I was pregnant. I went on three plane trips while pregnant and was wondering if the scanners were safe for my unborn baby. I never had to walk through one of these scanners during those trips, and so I did not give it much more thought. Then I started traveling with my daughter and wondered once again whether or not these scanners are safe for her. It is interesting that it never occurred to me to worry about this for my own safety, but I guess we are always more concerned about keeping our children safe.

Ignoring all the other issues (which may also be very important to you), let’s take a look at how these scanners work and whether or not they are safe for us to walk through.

There are two types of scanners that are currently in use in the United States: millimeter wave three dimensional scanners, and x-ray backscatter (two dimensional) scanners. They use different wavelengths of light (both invisible to the eye) and different methods of making an image.

A few weeks ago, I had a blog entry on how CT scans work. These body scanners are very similar in a lot of ways, so let’s review a few of those ideas, starting with wavelength. The electromagnetic spectrum (the different wavelengths and frequencies of light) is shown below:

I did not mention the relationship between wavelength () and frequency (f) in my previous blog entry, but here it is:


where c is the speed of light, 3 x 108 meters/second (or 186 miles/second). This is true for all wavelengths of light traveling through air. Who cares, you say? Well, this means that the millimeter wave beams have a frequency of ~ 300 GHz and below. For reference, your cell phone uses waves that have a frequency of ~ 1 GHz. The x-ray beams have frequencies of greater than a million GHz, or about 10,000 times that of the millimeter beam waves.

Again…this is interesting and all (if you are into numbers), but why should I care? Well, the energy contained in the individual balls of light (photons) in these beams is directly proportional to the frequency of light. That means that the x-ray photons hitting your body have more than 10,000x more energy than the millimeter wave photons. These high energy photons can actually ionize atoms – that means they can remove electrons from the atoms in your body, which can change the ways your atoms chemically bond and form all the organic material your body needs to function correctly.

So that is why x-rays are more dangerous than millimeter waves (which have not been shown to have any lasting harm on your body as far as I know). The question of safety seems to lie in the dosage. The backscatter scanners only send a very small amount of x-rays at your body.

According to the Transportation Security Administration (TSA):

“Advanced imaging technology is safe and meets national health and safety standards. Backscatter technology was evaluated by the Food and Drug Administration’s (FDA) Center for Devices and Radiological Health (CDRH), the National Institute for Standards and Technology (NIST), and the Johns Hopkins University Applied Physics Laboratory (APL). For comparison, a single scan using backscatter technology produces exposure equivalent to two minutes of flying on an airplane, and the energy projected by millimeter wave technology is thousands of times less than a cell phone transmission. Millimeter wave imaging technology meets all known national and international health and safety standards. In fact, the energy emitted by millimeter wave technology is 1000 times less than the international limits and guidelines.”

So this sounds like the scanners are safe, right? But the European Union has banned the x-ray backscatter scanners. From a European Commission Press Release:

“In order not to risk jeopardising citizens’ health and safety, only security scanners which do not use X-ray technology are added to the list of authorised methods for passenger screening at EU airports.”

Why? Well, the backscatter machines concentrate the x-rays on our skin. Unlike for CT scans, the x-rays do not travel through our bodies, but are reflected backwards to a detector to form an image. Some scientists, like the ones from the University of California at San Francisco that wrote a Letter of Concern printed in this news article, are concerned that the scanners have not be accurately tested and evaluated for this use. They believe that until these tests are done, the scanners should not be used in airports.

Okay, so we have heard this all before. They are safe. They are not safe. What does this mean? I feel that there are enough intelligent people (scientists, officials in Europe) who do not feel the machines are safe, especially for children. I will not walk through one of the x-ray backscatter machines with my daughter. (Of course, it is unlikely I will ever have to since I currently have to carry my daughter and that would defeat the purpose of the scanners – I could just hold her in front of my body wherever I was carrying something forbidden on airplanes.)

I do believe that the millimeter scanners are safe and have no problem walking through those. My next question was this: How can I tell which is which? It turns out they look completely different. There are number of pictures online showing what they look like. This article on The Science Behind Airport Body Scanners shows the scanners side by side so you can see what they look like.

Now I can make an educated decision about whether or not to walk through the scanner I see in the airport. I have only seen the millimeter wave machines and am not sure what airports have the x-ray backscatter scanners. If anyone has found a list of what airports carry which scanners, please leave a comment – I would be interested in knowing.

Side note: We are still in the midst of settling in and so the blog entries will likely be shorter and/or later than usual for a few weeks until I can find the time to work on them.

Scientific Parenting

I have recently started reading a book entitled Scientific Teaching by Jo Handelsman, Sarah Miller and Christine Pfund. I have had this book for several years now and never found the time to open it. Not that I have a lot of extra time in my day for intellectual reading now, but I have at least made it through most of the introduction. It has made me think a bit about how teaching, science and parenting are all related.

The book talks about approaching teaching science in the same way that we approach research in science. I have not had any real training in teaching (or parenting!), but have had a lot of training as a scientific researcher, so it makes sense to make use of that training to help me in teaching and parenting. Also, as the book points out, teaching science should be done in the same way that we approach science – completely separating the two will never help our students learn what science is all about. Science is about being curious, exploring the world, and solving problems – these are all things that I hope are important to my daughter as she grows, whatever other things she ends up doing.

So how DO I approach my scientific research?

Curiosity is important. I need to want to know the answers and be interested in exploring new ideas. Experiments rarely work the way you expect and a desire to follow the experiment where it takes you is essential to making progress in science. This is easy for babies – they are naturally incredibly curious. Encouraging this in my students is sometimes more challenging, but helps make the class more interesting and engaging for everyone involved.

I start my research by clearly defining my goal or the problem I would like to solve. In my lab, this usually involves using lasers to make a better, more accurate microscope for looking at fiber optic circuits (the optical wires used to send information along the internet so you can read this blog). In teaching, this means deciding what skills and information I want my students to have when they leave my class. In parenting, this can range from helping my daughter learn how to sit up or fall asleep on her own to figuring out why she is so fussy and always spits up after eating.

The next step, which is one that is often overlooked, is determining how I will measure my success – how will I know if I succeeded? This was one of the most difficult issues in my research since I was measuring a completely unknown object – how do I know if my measurements are accurate? How do I know that my students have learned the Physics and problem solving skills that I wanted them to learn and that they have not just blindly memorized some facts and answers to certain problems? My daughter sleeping better on her own seems like an obvious indicator that I was successful in that, but how do I know what things make my daughter a fussy eater when there are so many factors that may affect her behavior? Success may seem clear in those cases, but if I do not understand what caused the success, then I cannot be sure she will remain happy (and sleeping well).

Once I have a goal and a method of measurement, I still need to figure out how to achieve that goal. I start with what I already know and use that information to design a set of experiments to learn more about the problem so that I can come up with a solution. For examples, I can give my students a pretest to see what they already know and then try different types of teaching methods and see how each affect their performance. I can alter my diet (since I am breastfeeding) to see what foods in my diet make my daughter upset. In scientific experiments, this is the part I find the most fun – the troubleshooting. It’s a lot like detective work (which is why all those crime shows on television really focus on the cool science behind solving crimes). It can also be incredibly frustrating since most things you try do not work. And if you really want to solve a problem, you need to slowly, systematically try many different approaches.

This sounds like a good, rational approach to parenting, but it is easier said than done. The consequence of not finding a solution fast enough with my daughter is lack of sleep and a very unhappy, screaming baby. Using a more systematic, calm approach will still likely result in a solution faster, but it is hard to be calm and methodical when my baby is upset (and while I am so sleep deprived). I do try to approach each new challenge in teaching and parenting with a scientific mind when I am well rested enough to think of it!

I am looking forward to finding more time to read this book on Scientific Teaching – both to improve my teaching of Physics and also to help give me ideas on approaches with my daughter. Much of parenting is teaching, after all, and she still has a lot of exciting things to learn.