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The virus that causes COVID-19, SARS-CoV-2, is highly infectious, and can be spread by physical contact or by aerosols, sprays of tiny droplets we expel when we cough, sneeze, or even talk. We know now that surgical masks can block the transmission of the virus, but at the beginning of the pandemic, experts weren’t advising most people to wear them. The reasons for this were complicated, and included shortages that posed a danger to health care workers if there was a sudden run on the mask market.… Read the rest “Masks and soap”

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Three years ago I posted an article called “The Efficiency of the Human Body”, and it has proven to be popular. Then I posted an update last November. I’ve now learned more about the subject, and thought about it, and it’s time for another upgrade. Naturally, upgrades almost always involve an expansion, so there are two pieces now: This one, which explores the distribution of energy use in the resting body (our resting metabolic rate) and the next, which includes the material in the original post by describing energy distribution in the body in motion.… Read the rest “Human Energy Metabolism I: The Body at Rest”

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Nutritional scientists break down energy consumption into three components. The largest is Resting Energy Expenditure (REE), which I’ve examined in detail in the previous post. It accounts for 60-80% of our daily energy consumption. REE is the energy consumed at rest, when there’s no physical activity going on. Another 5-10% is used for digestion. The rest of our energy consumption is due to physical activity. These proportions can vary: if you’re a rider in the Tour de France, your daily physical activity will probably exceed your REE several times over.… Read the rest “Human Energy Metabolism II: The Body in motion”

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(Electron micrograph of SARS-CoV-2 from NIAID-RML)

It’s difficult to make predictions, especially about the future. That aphorism has been attributed to a long list of prognosticators, including the legendary wordsmith and NY Yankees catcher, Yogi Berra. Yogi was eminently quotable, including such gems as, “When you come to a fork in the road, take it.” But he wasn’t the first people’s scholar to have that insight into the difficulty of making predictions. It was apparently spoken in the Danish parliament, in 1937 or 1938, in Danish.… Read the rest “The future of coronavirus”

As of March 4, 2020 the novel coronavirus SARS-CoV-2, which causes COVID-19, has spread to more than 77 countries. More than 93,000 cases have been reported, and just under 3,200 deaths. It’s thought that the virus infected its first human victim in the city of Wuhan in China, in November, 2019. That case was apparently caused by transmission of SARS-CoV-2 from an animal. Since then, it has spread by human-to-human contact. The virus probably originated in bats, and then likely passed through another animal before it found its human host.… Read the rest “The Drift of Coronavirus”

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The environmental cost of beef production is well known: it generates a lot of greenhouse gases (GHG), compared to plant-derived foods or even meats such as pork or chicken. A major reason is that bovines’ stomachs use oxygen-free, “enteric” fermentation to digest grass, as described in a previous post. As a result, they burp up a lot of methane, which is a potent GHG.

The greenhouse gas contributions of methane, nitrous oxide, and fluorinated gases are encompassed by the term “CO2 equivalents” (CO2e).… Read the rest “The Environmental Cost of Beef”

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The agitated detective barks, “I need that DNA now. There’s a killer on the loose, and I have to know if we’ve got him in custody. I don’t give a damn how busy you are . . . ” We’ve all been there, on the edge of the couch, watching a cop show on TV and hoping that the magic of DNA testing will give a clear answer to the question “DidHeDoIt?” And indeed, DNA fingerprinting, more accurately ‘DNA profiling’, has transformed crimefighting.… Read the rest “DNA profiling I”

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Gel electrophoretic separation of DNA fragments containing Variable Numbers of Tandem Repeats. Each vertical lane contains one DNA sample. PCR-amplified fragments have been labeled, with different probes having different fluorescent labels. The red bands are internal calibration markers. The positions of the bands reflect their different mobilities, which in turn reflect their lengths (larger fragments move more slowly in electrophoresis). Capillary electrophoresis and automatic recording are used today instead of gel electrophoresis.

DNA profiling resulted from the convergence of scientific curiosity, technological advances, and the desire to provide a social benefit.… Read the rest “DNA profiling II”

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The material in this post has been upgraded and expanded in two posts, which describe human energy efficiency at rest and during vigorous exercise.

I first posted “The Inefficiency of Humans” in January 2017. It’s about the reasons that our energy metabolism provides only about 20-25% of the energy we consume as food for muscular work. I referred to this as our “inefficiency”, although it isn’t really that. The explanation and conclusions remain largely unchanged, but since then I’ve learned more about how energy metabolism is measured, so I’ve rewritten the post as this 2.0 version.… Read the rest “The Inefficiency of Humans”

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Laphroiag distillery on Islay. A group of international whisky tourists, an important source of revenue for malt distilleries in Scotland, is being shown around. The pagoda chimney is a common feature.

There is a good deal of science, and art, associated with single malt Scotch whisky (there’s no “e” in whisky in Scotland). Many of us know bits and pieces about it and how it’s made. But there may be readers, who, like me, are fans but also interested to learn more.… Read the rest “Single malt Scotch Whisky 101”