In his tribute to Arthur C. Clarke, John Dennehy mentions the opening scene from 2001: A Space Odyssey [Goodbye Arthur C. Clarke]. That was a scene that made a big impression on me as well, although I was a good deal older than John when I first saw it. Here it is.
Wednesday, March 19, 2008
Dawn of Man
In his tribute to Arthur C. Clarke, John Dennehy mentions the opening scene from 2001: A Space Odyssey [Goodbye Arthur C. Clarke]. That was a scene that made a big impression on me as well, although I was a good deal older than John when I first saw it. Here it is.
Arthur C. Clarke (1917 - 2008)
Science can destroy religion by ignoring it as well as by disproving its tenets. No one ever demonstrated, so far as I am aware, the non-existence of Zeus or Thor - but they have few followers now.
Arthur C. Clarke
It may be that our role on this planet is not to worship God-but to create him.
Arthur C. Clarke
I don't believe in God but I'm very interested in her.
Arthur C. Clarke
The greatest tragedy in mankind's entire history may be the hijacking of morality by religion.
Arthur C. Clarke
Information is not knowledge1, knowledge is not wisdom, and wisdom is not foresight. Each grows out of the other, and we need them all.
Arthur C. Clarke
1. This simple statement of fact is much more important in today's world than most people realize. Information should not be confused with knowledge.
[Photo Credit: ABCNews - Arthur C Clarke turns 90]
Billboard Censorship
According to the Grand Rapids Press, the Freedom From Religion Foundation is having trouble renting billboard space to advertise its message "Beware of Dogma" [Atheists claim censorship by billboard company]. The group that asked Hudsonville to remove God from the city's mission statement says it is having a hard time placing a billboard espousing its position.We discussed this issue before when I declared that this was a "freedom of speech" issue [What Freedom of Speech Really Means]. Many readers disagreed , stating that a private company had the right to discriminate on the basis of religious beliefs (or lack of them).
"This is new, that a billboard company is censoring us," said Annie Laurie Gaylor, co-president of the Freedom From Religion Foundation. The Madison, Wis.-based group, dedicated to the separation of church and state, bills itself as North America's largest group of atheists and agnostics with 12,000 supporters.
The billboard with the words "Beware of Dogma" and the group's Web address has been used around the country, she said.
Gaylor said CBS Outdoor Advertising in Grand Rapids declined to rent a billboard to Freeedom From Religion, telling her it had been through controversy in the past and community reaction would force the billboard down within a day. She is working with other area firms, she said, but their locations are not her first choice.
This time there's a very interesting discussion going on at RichardDawkins.net [ Atheists claim censorship by billboard company]. Read the comments on that site.
This is clearly a gray area but, personally, I'd like to live in a society where a private billboard company wasn't afraid to rent space to all kinds of groups—including those groups whose opinions aren't shared by the management of the company. I'd like to live in a society where everyone understood that this was ethical behavior on the part of the billboard company and they didn't hold the company responsible for the message on the billboard. Even better would be to live in a society where the average person celebrated diversity of opinion and looked forward to seeing and hearing about contrary views. They would also look forward to debating and discussing those views.1
1. In case anyone is wondering whether this can be construed as support for teaching the controversy, the answer is yes. I think Christian private schools should be teaching about evolution and the scientific views on the age of the Earth. I think public school students should be discussing the conflict between evolution and creationism (and science vs. religion).
[Photo Credit: More Billboards in Chambersburg PA]
Tuesday, March 18, 2008
Are You as Smart as a Third Year University Student? Q7
Question 1
Question 2
Question 3
Question 4
Question 5
Question 6Choose the INCORRECT statement about protein folding.
a) protein folding is a cooperative phenomenon
b) the energy of the final folded protein is at the bottom of a free energy well
c) most proteins fold extremely rapidly
d) folding is an enthalpy-driven reaction (ΔH)
e) protein folding can be assisted by molecular chaperones
Are You as Smart as a Third Year University Student? Q6
Question 1
Question 2
Question 3
Question 4
Question 5
Here are the names and structures of the aldohexoses. The common ones in biology are shown in blue.
Identify the monosaccharide shown below in three different views.
a) D-allose
b) D-altrose
c) D-galactose
d) D-glucose
e) D-mannose
THEME: Protein Structure
Jan. 28, 2007Free Love, the '60's, and Protein Synthesis
Feb. 8, 2007
How Proteins Fold
Feb, 11, 2007
Heat Shock and Molecular Chaperones
Feb. 13, 2007
Disulfide Bridges Stabilize Folded Proteins
THEME:
More posts on
Protein Structure
Feb. 14, 2007
The Anfinsen Experiment in Protein Folding
Feb. 15, 2007
Gene HSPA5 Encodes BiP-a Molecular Chaperone
Feb. 20, 2007Glycoproteins
Feb. 27, 2007
Collagen
March 12, 2007
How Cells Make Tryptophan, Phenyalanine, and Tyrosine
June 5, 2007
Protein Turnover
July 10, 2007
Fixing Carbon: the Structure of Rubisco
Aug. 1, 2007
Hemoglobin
Aug. 1, 2007
Myoglobin
Aug. 1, 2007
Heme Groups
Oct.13, 2007
HSP90 Structure
March 2, 2008The α Helix
March 10, 2008
β Strands and β Sheets
March 13, 2008
Loops and Turns
March 13, 2008
Levels of Protein Structure
March 13, 2008
Examples of Protein Structure
March 14, 2008
Evolution and Variation in Folded Proteins
April 3, 2008
The Peptide Bond
April 3, 2008
Ramachandran Plots
April 4, 2008
Levinthal's Paradox
April 6, 2008
One Protein - Two Folds
Monday, March 17, 2008
A Challenge to Jonathan Wells
On February 29th Jonathan Wells published a short review of a scientific paper by Maurice et al. (2008). You can read the original Wells posting at: The Irrelevance of Darwinian Evolution to Antibiotic Resistance.
Wells was trying to make a point. Concerning the work from Dardel's lab (Maurice et al, 2008), Wells claimed ...
Yet Darwinian evolution had nothing to do with it.We all know how creationists use the word "Darwinism." Most of the time, it's a synonym for evolution. All of the time, it's an attempt to obfuscate and confuse their audience. What Wells is saying is that evolution had nothing to do with the paper. All that happened was a bit of genetics. According to Wells, "Darwin's theory of the origin of species by natural selection" was not involved.
First, some bacteria happen to have a very complex enzyme (acetyltransferase), the origin of which Darwinism hasn’t really explained. Come to think of it, most cases of antibiotic resistance (including resistance to penicillin) involve complex enzymes, and the only “explanations” for them put forward by Darwinists are untestable just-so stories about imaginary mutations over unimaginable time scales.
Second, the acetyltransferase story is about minor changes in an existing species of bacteria. But Darwin’s theory isn’t really about how existing species change over time. People had been observing those long before 1859, and most of the new insights we’ve gained since then have come from genetics, not Darwinism. Yet Mendel’s theory of genetics contradicted Darwin’s, and Darwinists rejected Mendelian genetics for half a century. And although an understanding of genetics is important when dealing with antibiotic resistance, Darwin’s theory of the origin of species by natural selection is not.
Third, Dardel and his colleagues made their discovery using protein crystallography. They were not guided by Darwinian evolutionary theory; in fact, they had no need of that hypothesis.
The senior author of the paper posted a comment on Pharyngula saying, "Actually, we did indeed use darwinian evolution within this work (something unusual in structural biology)." [see Why the Right People Hate IDiots, and links within that posting].
Michael Egnor gallops to the defense of his hero. Today he posted a rebuttal to my criticism of him and Wells [Dr. Larry Moran, Darwinism, and Vicious Personal Invective]. Here's what Egnor says,
Dr. Wells pointed out that research on antibiotic resistance wasn’t guided by Darwinian evolutionary theory. That evolution occurred — that is, that the population of bacteria changed over time — is obviously true, and obviously was relevant to the antibiotic resistance research. Dr. Wells made the observation that the research owed little to Darwin’s theory that all biological complexity arose by natural selection without teleology.This is an incredible admission from a creationist. Egnor admits that the bacteria evolved. He then goes on to define some bizarre version of "Darwin's theory."1 But the cat is out of the bag. What we see here folks, is the recognition that there is a distinction between Darwinism and evolution by natural selection. We're still not clear about the difference but it seems that bacteria can evolve resistance to antibiotics.
Egnor admits that the paper used evolution but it just wasn't Darwinism.
Now let's see if Jonathan Wells agrees. I'll apologize to Wells if he will post a comment here, or on Evolution News & Views, agreeing to the following ..
I, Jonathan Wells, agree that Maurice et al. (2006) employed evolution by natural selection in their methodology. My position is that evolution by natural selection is not what I mean when I use the word Darwinian.Note that I'm not asking him to agree that "Darwinism" was involved in the paper. All he has to do is admit that evolution by natural selection is not what he means when he uses the word "Darwinian."
Michael Egnor has indicated that this is what Wells actually means. Now let's see if Wells himself will admit it.
1. The standard version of Darwin's Theory of Evolution by Natural Selection is that populations evolve due to the differential survival of individuals with a fitter genotype.
Maurice, F., Broutin, I., Podglajen, I., Benas, P., Collatz, E. and Dardel, F. (2008) Enzyme structural plasticity and the emergence of broad-spectrum antibiotic resistance. EMBO Rep. 2008 Feb 22 [Epub ahead of print] [PubMed]
What Is Consciousness?
There are two broad traditional and competing metaphysical views concerning the nature of the mind and conscious mental states: dualism and materialism. While there are many versions of each, the former generally holds that the conscious mind or a conscious mental state is non-physical in some sense. On the other hand, materialists hold that the mind is the brain, or, more accurately, that conscious mental activity is identical with neural activity.
ConsciousnessThere were lots of interesting things going on at SciBarCamp over the weekend but I want to pick out one topic that came up several times.
At one point there was a group of us talking about a number of different things when the topic of consciousness arose. One member of the group happened to mention that humans were special because they are "conscious."
Now, I happen believe that there's no such thing as "consciousness" in the sense of something tangible that we can point to and say. "That's consciousness." I think it's merely a descriptive term for brain activity. It's an epiphenomenon. Consciousness may be an important and useful word for describing the phenomenon but that's all it is. I don't know whether an octopus is conscious, or a dolphin, or a dog, or a chimpanzee. The reason I don't know this is because nobody can tell me what consciousness is.
Nobody in the group seemed to share my view. They all seemed to think that consciousness was something tangible and real—something that set humans off from the rest of life. Lee Smolin, a physicist at the Perimeter Institute, was particularly vocal about this. He expressed a great deal of surprise at the fact that anyone could question the existence of consciousness. In fact, Smolin insisted that the onus was on me to prove that consciousness doesn't exist.
I tried out some of my standard approaches on the group. For example, I asked them whether the character Data on Star Trek (TNG) was conscious. (The question applies equally well to any sophisticated robot.) Several people said yes. To me, this means that they define consciousness as simply complex electronic activity. If a robot/android can possess consciousness then how, exactly, do you define consciousness as anything else?
Other weren't sure whether Data was conscious or not. Unfortunately, they weren't able to explain why Data was not conscious and the other members of the Star Trek crew were conscious. At that point the group broke up because sessions were starting. My suspicion is that some people at the meeting were true dualists and they had never thought seriously about any other possibility.
The question is complex. Even a cursory review of the Wikipedia entry will be enough to confuse almost everyone [Consciousness]. What surprised me the most about the group I was talking to is that they seemed to take for granted that there was such a thing as a meaningful definition of consciousness that could be used to separate humans from all other animals. Some of them seemed to be genuinely puzzled by the fact that they couldn't define consciousness. It was as though they had never thought about the problem before.
The question came up again in the afternoon when I attended a discussion led by Robert Sawyer. Sawyer is a science fiction author, and a very good one at that. One of his books Calculating God is an excellent story about discovering God. I highly recommend it. His latest book is Rollback and I will be buying a copy as soon as I get to a bookstore. I've met Robert Sawyer before. He's been to Skeptics meetings and to the Centre for Inquiry. He's a smart guy, and he knows it. I like people like that.
Sawyer is currently working on a series of books where the World Wide Web acquires consciousness. He organized a session to talk about his books under the title "World Wide Web Gaining Consciousness." As he explained it, this was supposed to be a brainstorming session to help him with his book. It was also pretty good publicity.
Sawyer began by explaining that consciousness evolved in humans about 40,000 years ago. We know this, according to Sawyer, because that's when we see the first signs of human adornment. Apparently, the ability to be self-aware is the hallmark of consciousness. In his book, the World Wide Web becomes self-aware and conscious.
There was a lot of discussion about what it meant for the WWW to be conscious. There were some questions about how the characters in the book knew that the WWW had become conscious. This was quite interesting. Most of the people in the room seemed to be having some difficulty understanding what it meant for Web to be conscious.
At one point I asked whether consciousness was ever defined and whether the characters in the book discussed the idea that there might not be any such thing as consciousness. Sawyer responded that, of course, everyone thinks about such things and so will his characters. I mentioned that some people don't seem to know about the difficulty in defining consciousness and don't seem to have thought about the fact that it may not actually exist.
I called for everyone to raise their hands if they had thought about the idea that consciousness may not exist. Everyone raised their hands. This is when Sawyer said that it's not a good idea to think you are the smartest person in the room, Larry.
It was embarrassing. The result of the survey indicated that everyone in the room had pondered the consciousness problem and all but one (me) had reached the same conclusion after careful thought. Consciousness, which none of them could define, exists and furthermore, it evolved uniquely in humans in the recent past.1 Whatever it is, the same kind of consciousness was also able to arise spontaneously in a network of fiber optic cables.
I admit I was wrong. The evidence is clear. All smart people have thought about these things. Most of them have made a "conscious" decision to be dualists and reject the notion of consciousness as a mere epiphenonenon. The lunch group seems to have been an exception.
Later on the the same session, another science fiction writer named Peter Watts mentioned that consciousness arose by natural selection. I pointed out that there was another possibility; namely that it could evolve by accident. This would be similar to how it evolved in the World Wide Web. (Sawyer did not indicate that natural selection was involved there.) Peter assured me in no uncertain terms that he knew as much about evolution as I did.
Science fiction writers sure know a lot of things.
In case you want the see another version of this story go to Robert Sawyer's blog and read what he has to say about this discussion [SciBarCamp].
1. I wonder how this actually worked. Since consciousness evolved it must have a genetic component. Otherwise it's not evolution. Presumably a mutation causing consciousness arose some 40,000 years ago. It rapidly spread though the population in a short period of time. It must have been interesting times. In some families you would have had a mixture of children; some were conscious and some were not. How did they tell which was which?
Happy St. Patricks Day!!!
Today's the day when the Irish—and people who want to be Irish—celebrate by doing typically Irish things; like drinking green beer, dancing Irish jigs, and going to mass. (?)1My ancestors on my mother's side are (mostly) Irish. My grandfather was a Doherty (O'Doherty). That's the name at the top of the map in country Donegal. That side of the family came to Canada in 1802 and the Irish blood has been diluted—most notably by American refugees from the Revolutionary War (United Empire Loyalists) (gasp!).
The O'Doherty's are descended from Niall Noigíallach who kidnapped St. Patrick.
My grandmother was a Foster from Fermanagh. That's by the two lakes (Lower Lough Erne and Upper Lough Erne) in the upper central part of the country near the seat of the Maguires. Her family came to Canada in 1865 but both of her parents were Irish so at least 1/4 of my genes are undiluted Irish. I'll drink to that.We don't talk about the nasty little fact that the Foster's were probably English invaders from the 1600's. As they say, somebody had to civilize the Irish and it might as well have been the English!
One of the reasons why the topic was avoided by my grandparents was because the O'Doherty clan was almost wiped out by the English during the O'Doherty rebellion in 1608 led by Sir Cahir O’Doherty. Some of the survivors had to flee to Skye to avoid being hung. I descend from those refugees.
1. This entire post is a copy of my first St. Patrick's Day post in 2007.
Monday's Molecule #65
Some of the most important contributions to the biological sciences aren't associated with a particular molecule. This is one of those cases. The figure on the right is taken from the Nobel Lecture of the Laureate who will be featured on Wednesday. It illustrates the problem that was being addressed. The real contribution of this Nobel Laureate is more easily illustrated by using a mathematical equation. The equation is shown below.
Your task is to identify the general field that's being discussed and to describe the significance of the equation. You must explain all the variables in the equation and why it was important enough to contribute to the award of a Novel Prize. Naturally, you also have to name the Nobel Laureate. The first person to correctly describe the equation and name the Nobel Laureate wins a free lunch at the Faculty Club. Previous winners are ineligible for one month from the time they first collected the prize. There is only one ineligible candidate for this week's reward.
THEME:
Nobel Laureates
Send your guess to Sandwalk (sandwalk (at) bioinfo.med.utoronto.ca) and I'll pick the first email message that correctly identifies the equation and the Nobel Laureate(s). Note that I'm not going to repeat Nobel Laureates so you might want to check the list of previous Sandwalk postings.
Correct responses will be posted tomorrow along with the time that the message was received on my server. I may select multiple winners if several people get it right.
UPDATE: We have a winner! Haruhiko Ishii of the Dept. of Physics at UCSD got the right answer. I've issued an invitation to meet for lunch.
The figure shows the transition from a random coiled polymer to one that has more structure. The process was studied by Paul Flory who won the Nobel Prize in 1974 for his work on the physical chemistry of macromolecules. One of his important contributions was the concept of intrinsic viscosity [η]. This is a measure of viscosity that takes into account the contribution of a solute. The intrinsic viscosity depends on the viscosity of the solvent in the absence of solute and the change that takes place when the solute occupies a certain volume of the solution.
The equation for solving intrinsic viscosity can be written several ways. In the example shown above, K and α represent constants that depend on the type of solute. M is the molecular weight of the polymer.
IDiots Get Public Funding for their Schools in Alberta
Scott Rowed is one of the Alberta representatives for the Centre for Inquiry. He has an op-ed piece in Saturday's Edmonton Journal where he points out the dangers of giving public money to faith-based schools. These schools are permitted by law to discriminate on the basis of religious belief. That's not new. Here in Ontario we have a Roman Catholic school system that is fully funded by taxpayer money.The shocking thing is the extent to which some faith-based schools will go to exclude rational thought and genuine education. For example, Scott says,
To have this choice of placing their children into a faith school, parents must obtain a letter from a preacher praising their church devotion and sign a statement of faith. This quote, from the constitution and bylaws of Fort McMurray Christian School Society, is typical: "We believe the Genesis account of creation is to be understood literally; that man was created in God's own image and after His own likeness; that man's creation was not by evolution or change of species or development through interminable periods of time from lower to higher form."I agree with Scott. This is outrageous. Any school system that explicitly denies one of the fundamental facts of science should not receive a single penny of taxpayer's money.1
Parents who believe that the first cowboy saddled up a triceratops have more choice as their children can attend either a faith school or a public school. On the other hand, Christians who accept evolution, non-believers, and followers of other faiths can enrol their children only in a public school.
There's only one rational solution to the problem. The government must fund a single secular school system. That means eliminating funding for the Catholic schools as well as the IDiot schools. If you live in Ontario, join the One School System Network and work toward achieving this goal.
1. I wonder if Ben Stein will make a movie about this kind of discrimination? It's obvious that any teacher who believes in evolution will never get a job in one of these schools and any student who starts to believe in evolution will be EXPELLED.
[Photo Credit: Rahime at Prayer for Rain]
Friday, March 14, 2008
A Visit to Guelph
Next Wednesday I'll be visiting Guelph University (Ontario, Canada) to give a lecture on "Evolution as a Fact and a Theory." The hosts are Guelph Skeptics [Lecture].Maybe I'll see some of you there?
Evolution and Variation in Folded Proteins
As a general rule, the primary structure of a protein (amino acid sequence) ultimately determines it's final three-dimensional shape1. Proteins fold spontaneously to adopt a specific structure that minimizes free energy. The folded protein occupies the bottom of a free energy well [How Proteins Fold, The Anfinsen Experiment in Protein Folding, Disulfide Bridges Stabilize Folded Proteins, Heat Shock and Molecular Chaperones]. Each protein has a characteristic shape associated with its function. When we discuss the evolution of proteins, we like to divide the residues into three categories as shown below for the structure of myoglobin from sperm whale (Physeter catodon) [PDB 1A6M].
Myoglobin is a small protein with a bound heme group (shown as a space-filling molecule). It carries oxygen in the bloodstream and tissues. The oxygen molecule binds to the active site of the protein near one side of the heme group. There are specific amino acid residues at the active site that are absolutely required for binding oxygen. As you might expect, these amino acids are highly conserved—they will be found at that position in myoglobin from humans or any other species.The second category of amino acid residues makes up the hydrophobic interior of the protein. Myoglobin is an all-α-helical protein and several of the helices group together to form a helix bundle. The interior of that bundle consists largely of hydrophobic amino acid residues. This is what stabilizes the three-dimensional structure and causes the polypeptide chain to spontaneously fold after it is synthesized.
The third category of residues is the surface residues. These are usually hydrophilic residues that interact with the surrounding water. The surface residues don't make as much of a contribution to the overall three-dimensional structure so their exact composition can be quite variable.
The class of proteins to which myoglobin belongs is called "globins." There are two other globins that you are probably familiar with: α-globin and β-globin are the two polypeptides that come together to form an α2β2 hemoglobin tetramer. The three proteins (myoglobin, α-globin, and β-globin) descended by gene duplication from a common ancestral globin several hundred million years ago. Today their amino acid sequences are quite different due to the accumulation of random mutations and fixation by random genetic drift. In spite of the differences in primary structure, the three-dimensional structures of the three proteins are very similar. This can easily be shown by superimposing the three structures as shown in the figure (myoglobin=green, α-globin=blue, β-globin=purple).
Most people don't appreciate the amount of variation that underlies this conserved three-dimensional structure. It's worth taking a look at a bunch of aligned globin sequences from different species to see exactly which amino acids are highly conserved and which positions can tolerate almost any amino acid.
Let's go to the Pfam (protein family) database at the Sanger Institute in Cambridge (UK). The entry for the globin family is Globin PF00041. Click on "Alignments" in the left sidebar. This link takes you to the alignment page where you can create an alignment of all the known globin sequences. Choose 75 seeds (default) in the first table and select "Pfam viewer" from the pull-down menu under "Viewer." Click "View" to see the alignments.Highly conserved amino acid residues are highlighted by vertical shading in the Pfam view. The first thing you should notice is that there are very few amino acids that are invariant. The conserved residue on the left (blue) is tryptophan (W). It's present in most of the globins from different species but not all. Look at the other positions and note that in most cases a variety of different amino acid residues can be substituted. Sometimes only hydrophobic residues (blue) can be found at a particular site and sometimes there are other restricted choices. Lots of insertions and deletions (dots) can be tolerated without major disruption to the overall three-dimensional structure.
Data like this reveals that the amino acid residues in the active site are usually conserved. Residues in the hydrophobic core are moderately conserved. And residues on the surface are hardly conserved at all.
The point is that there are literally billions of different proteins that have the same shape as globins and still function as carriers of oxygen. This is an important point. Opponents of evolution often take a single globin from a single species and calculate the probability that such a structure will form. They assume that only one out of twenty amino acids can be found at each position and the resulting probability (e.g., 20020) is enormous. Thus, they conclude, such a protein could never form by chance. They don't seem to appreciate the fact that we already know of billions of different proteins that can function as globins.
There are many other examples of this observation. The four structures below show the conformation of the cytochrome c polypeptide chain from tuna, rice, yeast, and a bacterium. The amino acid sequences have diverged considerably from their common ancestor of 3 billion years ago but the structures are very similar.
We conclude that the amino acid sequence of a polypeptide determines how it will fold in three-dimensional space but there are billions of different amino acid sequences that will adopt the same structure.
Finally, let's look at a more complicated example. The enzymes lactate dehydrogenase (below left) and malate dehydrogenase (below right) share a common ancestor even though they are different enzymes. This is a case where substitutions of amino acid residues in the active site gave rise to a new activity. Today the amino acid sequence similarity is barely above the threshold for defining homology but the structures are still very similar.
1. Other factors that contribute are bound ligands, such as heme groups, and interactions with other proteins as in multimeric proteins with sifferent subunits.
Escalators Are Dangerous
From Science News [Rate Of Escalator Injuries To Older Adults Has Doubled]
Using U.S. Consumer Product Safety Commission data, the researchers found nearly 40,000 older adults were injured on escalators between 1991 and 2005. The most frequent cause of injury was a slip, trip or fall resulting in a bruise or contusion. The most common injuries were to the lower extremities. However, most injuries were not serious. Only 8 percent of the 39,800 injured were admitted to the hospital after evaluation in an emergency department.
"Although escalators are a safe form of transportation, fall-related injuries do occur. Older adults, especially those with mobility, balance or vision problems, should use caution while riding an escalator and especially when stepping on or off. They should not try to walk up or down a moving escalator, carry large objects, or wear loose shoes or clothing while riding since these appear to be associated with an increased risk of falling," said Dr. O'Neil, associate professor of clinical pediatrics at the IU School of Medicine.
500,000 Visitors
Sometime on Wednesday night Sandwalk notched up 500,000 visitors. To put this in perspective, after 16 months of blogging the total number of visitors is less than half the number who visit Pharyngula in one month.
This is depressing. We need to do something about it. Is there any way we can shut down Pharyngula?
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