Category Archives: Science

“You absorb fewer calories eating toast that has been left to go cold”

The Economist: Death of the calorie. “For more than a century we’ve counted on calories to tell us what will make us fat. Peter Wilson says it’s time to bury the world’s most misleading measure.”

“There’s a further weakness in the calorie-counting system: the amount of energy we absorb from food depends on how we prepare it. Chopping and grinding food essentially does part of the work of digestion, making more calories available to your body by ripping apart cell walls before you eat it. That effect is magnified when you add heat: cooking increases the proportion of food digested in the stomach and small intestine, from 50% to 95%.
[…]
The difficulty in counting accurately doesn’t stop there. The calorie load of carbohydrate-heavy items such as rice, pasta, bread and potatoes can be slashed simply by cooking, chilling and reheating them. As starch molecules cool they form new structures that are harder to digest. You absorb fewer calories eating toast that has been left to go cold, or leftover spaghetti, than if they were freshly made. Scientists in Sri Lanka discovered in 2015 that they could more than halve the calories potentially absorbed from rice by adding coconut oil during cooking and then cooling the rice. This made the starch less digestible so the body may take on fewer calories (they have yet to test on human beings the precise effects of rice cooked in this way). That’s a bad thing if you’re malnourished, but a boon if you’re trying to lose weight.”

I read this article last week and was reminded of it by this MetaFilter post that has more links on the subject.

Plastic, paper, or cotton bags?

NPR Planet Money: Are Plastic Bag Bans Garbage?

“It was only about 40 years ago that plastic bags became standard at U.S. grocery stores. This also made them standard in sewers, landfills, rivers and the Great Pacific Garbage Patch. They clog drains and cause floods, litter landscapes and kill wildlife. The national movement to get rid of them is gaining steam — with more than 240 cities and counties passing laws that ban or tax them since 2007. New York recently became the second U.S. state to ban them. But these bans may be hurting the environment more than helping it.
[…]
Plastic haters, it’s time to brace yourselves. A bunch of studies find that paper bags are actually worse for the environment. They require cutting down and processing trees, which involves lots of water, toxic chemicals, fuel and heavy machinery. While paper is biodegradable and avoids some of the problems of plastic, Taylor says, the huge increase of paper, together with the uptick in plastic trash bags, means banning plastic shopping bags increases greenhouse gas emissions. That said, these bans do reduce nonbiodegradable litter.
[…]
A 2011 study by the U.K. government found a person would have to reuse a cotton tote bag 131 times before it was better for climate change than using a plastic grocery bag once. The Danish government recently did a study that took into account environmental impacts beyond simply greenhouse gas emissions, including water use, damage to ecosystems and air pollution. These factors make cloth bags even worse. They estimate you would have to use an organic cotton bag 20,000 times more than a plastic grocery bag to make using it better for the environment.”

It’s neither black nor a hole

NPR: Earth Sees First Image Of A Black Hole.

“Researchers at the Event Horizon Telescope project say they were able to create an image of a black hole by using a network of eight radio telescopes to create “a virtual telescope dish as large as the Earth itself,” the National Science Foundation says.

The breakthrough, Doeleman said, came after a decade of work to align the myriad working parts of the project and gain the highest resolution possible from the Earth’s surface. Finally, in April of 2017, he said, “all of the dishes in the Event Horizon Telescope swiveled, turned and stared” at the core of M87. From that data came the image that was released Wednesday.”

See also: XKCD: M87 Black Hole Size Comparison.

Graphische Biographie zum Humboldt-Jahr

Deutsche Welle: Andrea Wulf: “Humboldt bringt Kunst und Wissenschaft zusammen”. “Ihre Humboldt-Biografie wurde 2015 ein Weltbestseller. Zum Humboldt-Jahr veröffentlicht Andrea Wulf nun ein weiteres Werk über den berühmten Forscher. Mit der DW sprach sie über ihre “illustrierte Entdeckungsreise”.”

“Deutsche Welle: Frau Wulf, Sie haben 2015 mit der Monumentalbiografie “Alexander von Humboldt und die Erfindung der Natur ” einen preisgekrönten Weltbestseller vorgelegt. Was hat Sie veranlasst, sich Humboldt jetzt noch einmal auf ganz andere Weise zu nähern: mit einem farbenprächtigen, opulent illustrierten Buch über seine berühmte Südamerika-Expedition?

Andrea Wulf: Humboldt wird immer gern als Wissenschaftler dargestellt, dabei wird aber vergessen, dass er auch ein Künstler war. Humboldt bringt die Kunst und die Wissenschaft zusammen, und ich wollte ein Buch machen, das das auch wirklich zeigt. Der eigentliche Anlass dafür war, dass Ende 2013 die legendären Südamerika-Tagebücher von Humboldt, die bis dahin in Privatbesitz waren, erstmals der Öffentlichkeit verfügbar gemacht wurden, weil die Stiftung Preußischer Kulturbesitz sie gekauft hat. Sie wurden digitalisiert und waren ab Ende 2014 online verfügbar. Als ich diese Dokumente gesehen habe, hat es mich einfach umgehauen.”

“Ein unübersichtlicher Chemikaliencocktail”

Deutsche Welle: E-Zigaretten verursachen Herzinfarkte und Depressionen. “Eine US-Studie zeigt, dass E-Zigaretten gefährlicher sind, als viele glauben: Raucher riskieren Herzkrankheiten und Depression. Allerdings sind die herkömmlichen Zigaretten noch viel gefährlicher.”

“”Ich möchte nicht, dass irgendeiner meiner Patienten oder Familienmitglieder E-Zigaretten ‘dampft'” sagte [Medizinprofessor Mohinder] Vindyhal. “Wir haben herausgefunden, dass es keine Rolle spielt, wie oft jemand E-Zigaretten konsumiert. Selbst wenn es nur an einigen Tagen [in der Woche] geschieht, steigt trotzdem die Wahrscheinlichkeit eines Herzinfarktes oder einer koronaren Herzkrankheit an.”

Seine Studie widerlegt die weitverbreitete Auffassung, dass E-Zigaretten deutlich ungefährlicher sind als normale Zigaretten, weil in ihnen keine Rauchgase entstehen und damit weniger Gifte aus dem Verbrennungsprozess in die Lunge gelangen.”