Author Archives: curiouscat

How Aerobic Exercise Suppresses Appetite

How aerobic exercise suppresses appetite

Those of you who run, bike, swim, or otherwise engage in aerobic exercise have probably noticed that in spite of burning scads of calories during your chosen activity, the last thing you feel when you’re finished is hungry.
…
The researchers discovered that aerobic exercise produces increased peptide YY levels while lowering ghrelin, leading to decreased appetite. Weight training was associated with a decrease in ghrelin, but no change in peptide YY, meaning that there was a net suppression of appetite, but not to the same degree as observed with treadmill training. In both cases, changes in appetite lasted for about two hours.

I know I find this to be true for me.

Bird Brain

Bird-brains smarter than your average ape

In a recent study 20 individuals from the great ape species were unable to transfer their knowledge from the trap-table and trap-tube or vice versa, despite the fact that both these puzzles work in the same way. Strikingly the crows in The University of Auckland study were able to solve the trap-table problem after their experience with the trap-tube.

“The crows appeared to solve these complex problems by identifying causal regularities,” says Professor Russell Gray of the Department of Psychology. “The crows’ success with the trap-table suggests that the crows were transferring their causal understanding to this novel problem by analogical reasoning. However, the crows didn’t understand the difference between a hole with a bottom and one without. This suggests the level of cognition here is intermediate between human-like reasoning and associative learning.”

“It was very surprising to see the crows solve the trap-table,” says PhD student Alex Taylor. “The trap table puzzle was visually different from the trap-tube in its colour, shape and material. Transfer between these two distinct problems is not predicted by theories of associative learning and is something not even the great apes have so far been able to do.”

StoryCorps: Passion for Mechanical Engineering

StoryCorps is an effort to record and archive conversations. NPR plays excerpts of one of the conversations each week, and they are often inspiring. They are conversation between two people who are important to each other: a son asking his mother about her childhood, an immigrant telling his friend about coming to America, or a couple reminiscing on their 50th wedding anniversary. By helping people to connect, and to talk about the questions that matter powerful recording are made. Yesterday I heard this one – A Bent For Building, From Father To Daughter:

“Can a girl be an engineer?” she asked her father. His answer: There was no reason she couldn’t.
…
Anne loved to take her things apart. It was mostly her toys — until the day she took a clock apart and spread its contents out.

When her father asked what had happened, his daughter answered, “Oh, I took it apart. Daddy fix.”

And as her dad put things back together, Anne would sit by, watching intently to see how things were made. “Did you ever notice that I always followed you around the shop, watching?” Anne asked Ledo.

“I thought there was a magnet hooked up to me and to you.”

Beautiful Basics of Science

Natalie Angier’s recent book, The Canon, is a great overview of the world of science. The book gets a bit too carried away with being cute (A top-of-the-line radar can pinpoint the whereabouts of a housefly two kilometers away, although clearly this is a radar with far too much time on its hands), but overall is excellent. Such lines are find, in moderation, but this book has too many by a factor of 10 or 100. Some gems from the book:

page 19: Science is not a rigid body of facts. It is a dynamic process of discovery.

page 47: true happenstance bears a distinctive stamp, and until you are familiar with its pattern, you are likely to think it messier, more haphazard, than it is… it often makes people uncomfortable by not looking random enough.

page 92: while the different atoms are all about the same size – a tenth of a billionth of a meter across – they diverge in their mass, in the number of protons and neutrons with which their nucleus is crammed.

page 99: If you drag a comb through your dry hair, the comb will strip off millions of electrons from the outermost shells of the atoms of you coiffure.

The details are great (about a trillion electrons are involved when you get a small static electricity shock) and it is an excellent book for those interested in an overview of science that does not require in depth science education to follow. And yet with a good background in science the material presented is still plenty interesting.

Friday Cat Fun #9 with a Guest Star. A Dolphin.

Fun but, pretty short. Why not see some more cat fun: Bunny and Kittens: Friday Cat Fun #5 – Cat running up a $300 water bill – Dolphin Rescues Beached Whales

How We Found the Missing Memristor

How We Found the Missing Memristor By R. Stanley Williams

For nearly 150 years, the known fundamental passive circuit elements were limited to the capacitor (discovered in 1745), the resistor (1827), and the inductor (1831). Then, in a brilliant but underappreciated 1971 paper, Leon Chua, a professor of electrical engineering at the University of California, Berkeley, predicted the existence of a fourth fundamental device, which he called a memristor. He proved that memristor behavior could not be duplicated by any circuit built using only the other three elements, which is why the memristor is truly fundamental.
…
the memristor’s potential goes far beyond instant-on computers to embrace one of the grandest technology challenges: mimicking the functions of a brain. Within a decade, memristors could let us emulate, instead of merely simulate, networks of neurons and synapses. Many research groups have been working toward a brain in silico: IBM’s Blue Brain project, Howard Hughes Medical Institute’s Janelia Farm, and Harvard’s Center for Brain Science are just three. However, even a mouse brain simulation in real time involves solving an astronomical number of coupled partial differential equations. A digital computer capable of coping with this staggering workload would need to be the size of a small city, and powering it would require several dedicated nuclear power plants.

High School Inventor Teams @ MIT

Sadly MIT deleted the video after having it live for several years.

Lemelson-MIT InvenTeams is a national grants initiative of the Lemelson-MIT Program to foster inventiveness among high school students. The webcast above shows a high school team presenting a project they completed to create a solution to provide clean water. This stuff is great. I love appropriate technology. I love seeing kids think and create effective solutions to real problems. This is how you get kids to learn – not boring classes (at least kids like me).

The students are passing on the project to students at their school to continue to work on. (MIT TechTV used to have many more presentation by other InvenTeams – not anymore 🙁 ) InvenTeams and MIT deserve a great deal of credit for creating such great learning opportunities and great solutions for the world.

InvenTeams composed of high school students, teachers and mentors are asked to collaboratively identify a problem that they want to solve, research the problem, and then develop a prototype invention as an in-class or extracurricular project. Grants of up to $10,000 support each team’s efforts. InvenTeams are encouraged to work with community partners, specifically the potential beneficiaries of their invention.

Dolphins Using Tools to Hunt

photo of a dolphin with a sponge it uses to hunt

Photograph of dolphin with a sponge it uses to hunt, courtesy of Ewa Krzyszczyk, PLoS, high resolution.

Cool open access research from PLoS One, Why Do Dolphins Carry Sponges?

Tool use is rare in wild animals, but of widespread interest because of its relationship to animal cognition, social learning and culture. Despite such attention, quantifying the costs and benefits of tool use has been difficult, largely because if tool use occurs, all population members typically exhibit the behavior. In Shark Bay, Australia, only a subset of the bottlenose dolphin population uses marine sponges as tools, providing an opportunity to assess both proximate and ultimate costs and benefits and document patterns of transmission.

We compared sponge-carrying (sponger) females to non-sponge-carrying (non-sponger) females and show that spongers were more solitary, spent more time in deep water channel habitats, dived for longer durations, and devoted more time to foraging than non-spongers; and, even with these potential proximate costs, calving success of sponger females was not significantly different from non-spongers. We also show a clear female-bias in the ontogeny of sponging. With a solitary lifestyle, specialization, and high foraging demands, spongers used tools more than any non-human animal. We suggest that the ecological, social, and developmental mechanisms involved likely (1) help explain the high intrapopulation variation in female behaviour, (2) indicate tradeoffs (e.g., time allocation) between ecological and social factors and, (3) constrain the spread of this innovation to primarily vertical transmission.

The dolphins use the sponge to push along the ocean floor and disturb fish, that are hidden. Once the fish start swimming away the dolphin abandons the sponge and catches and eats the fish. Then the dolphin goes back and gets the sponge and continues.

How Antibiotics Kill Bacteria

Since the first antibiotics reached the pharmacy in the 1940s, researchers discovered that they target various pieces of machinery in bacterial cells, disrupting the bacteria’s ability to build new proteins, DNA, or cell wall. But these effects alone do not cause death, and a complete explanation of what actually kills bacteria after they are exposed to antibiotics has eluded scientists.
…
The group found that all bactericidal antibiotics, regardless of their initial targets inside bacteria, caused E. coli to produce unstable chemicals called hydroxyl radicals. These compounds react with proteins, DNA, and lipids inside cells, causing widespread damage and rapid death for the bacteria.
…
With the results of these two experiments, the researchers were able to identify three major processes implicated in gentamicin-induced cell death: protein transport, a stress response triggered by abnormal proteins in the cell membrane, and a metabolic stress response.

Global Cancer Deaths to Double by 2030

Global Cancer Deaths to Double by 2030 by Salynn Boyles

Cancer deaths are projected to more than double worldwide over the next two decades, largely from a dramatic increase in cancer incidence in low- and middle-income countries driven by tobacco use and increasingly Westernized lifestyles.

A new report from the International Agency for Research on Cancer (IARC) explores the global burden of cancer, which is poised to become the leading cause of death worldwide by 2010. The report predicts that by 2030, 27 million new cancer cases and 17 million cancer deaths will occur each year worldwide. That compares to 12 million new cancers and slightly less than 8 million cancer deaths in 2007.

People really need to stop smoking. And we are pretty lame a society when we inflict such needless disease and death on our fellow humans. Curing millions of cancer patients 20 years from now will be very hard. but it isn’t hard to “cure” millions of them today. We just need people not to pay a lot of money to give themselves cancer by smoking.