The movements of the wing in flight
Calliphora vicina] during flight, seen from below the horizontal plane passing through the wing-roots.
The anatomy, physiology, morphology and development of the blow- fly (Calliphora erythrocephala) A study in the comparative anatomy and morphology of insects; with plates and illustrations executed directly from the drawings of the author by B. Thompson Lowne (1890)
Starting late last week, with several small protests denouncing a hike in public transport fares, demonstrations flared up yesterday, encompassing larger public anger at poor public services, police violence and government corruption. More than 200,000 took to the streets of Brazil’s biggest cities yesterday, voicing frustration with the billions of dollars set aside for upcoming sports events like the World Cup and the 2014 Olympics, despite crushing levels of poverty in some places, and underfunded public education, health, security and transportation. Though the majority of the protests were peaceful, a few violent demonstrations were broken up by police in Rio de Janeiro.
There’s a lot of people in the comic shop, so I must shot the photo from the outside…
This image of Mercury, acquired by the Mercury Dual Imaging System (MDIS) aboard NASA’s MESSENGER mission on April 23, 2013, allows us to take a step back to view the planet. Prior to the MESSENGER mission, Mercury’s surface was often compared to the surface of Earth’s moon, when in fact, Mercury and the moon are very different. This image in particular highlights many basins near Mercury’s terminator, including Bach crater. Many craters with central peaks and the nearby bright rays of Han Kan crater are also evident.
Once per week, MDIS captures images of Mercury’s limb, with an emphasis on imaging the southern hemisphere limb. These limb images provide information about Mercury’s shape and complement measurements of topography made by the Mercury Laser Altimeter (MLA) of Mercury’s northern hemisphere.
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Hemoglobin: Binding O2: Cooperation Makes It Easier
The gorgeous and colourful animination above, from the Research Collaboratory for Structural Bioinformatics Protein Data Bank (RCSB PDB), illustrates the conformational change upon oxygen binding to hemoglobin(1).
What is hemoglobin?
Hemoglobin is a remarkable metalloprotein (a protein that contains a metal ion), found in red blood cells, that plays an important role in oxygen transport. Hemoglobin is a heterotetramer consisting of 2 α subunits (light pink and the other one can’t be seen) and 2 β subunits (light purple and light blue), arranged in 2 αβ subunits (2 sets of dimers). Each subunit contains one heme group (red) — a protoporphyrin ring with Fe2+ in the ring centre — resulting in four heme groups in total.(2)
How does hemoglobin bind O2?
Interestingly, hemoglobin binds O2 (teal) cooperatively: when one heme group binds to O2, it increases the other heme groups’ affinity (ability to bind) for O2. This is a type of allosteric interaction — the change in shape of a protein that results from binding of a molecule at the allosteric site (a site other than the active site).(2)
Why does this happen?
When O2 is not bound (deoxy), Fe2+ lies a little outside of the protoporphyrin ring. When O2 is bound (oxy), Fe2+ ”pops” into the ring, pulling with it a histidine (yellow), His, residue. Also attached to His is an α-helix (orange), which also shifts. All of this movement disrupts and forms new interactions between the α1β1-α2β2 interface.(1) It is this conformational change that increases the other hemes’ ability to bind to O2. Noticeably, as more O2 binds to hemoglobin, the α1β1 dimer will rotate 15° relative to the α2β2 dimer, which can be observed in the animation.2
(1) Goodsell, D., & Dutta, S. (2003). Hemoglobin RCSB Protein Data Bank DOI: 10.2210/rcsb_pdb/mom_2003_5
(2) Krisinger, M. BIOC 202 Lecture on Protein Function. Presented at the University of British Columbia. May 27, 2013.
Can I just stop you for a minute and note how fucking amazing it is that one of our greatest living cartoonists is not only teaching this class, but she’s letting us all follow along? Incredible.
Two or three times a year, NASA’s Solar Dynamics Observatory observes the moon traveling across the sun, blocking its view. While this obscures solar observations for a short while, it offers the chance for an interesting view of the shadow of the moon. The moon’s crisp horizon can be seen up against the sun, because the moon does not have an atmosphere. (At other times of the year, when Earth blocks SDO’s view, the Earth’s horizon looks fuzzy due to its atmosphere.)
If one looks closely at such a crisp border, the features of the moon’s topography are visible, as is the case in this image from Oct. 7, 2010. This recently inspired two NASA visualizers to overlay a 3-dimensional model of the moon based on data from NASA’s Lunar Reconnaissance Orbiter, or LRO, into the shadow of the SDO image. Such a task is fairly tricky, as the visualizers — Scott Wiessinger who typically works with the SDO imagery and Ernie Wright who works with the LRO imagery — had to precisely match up data from the correct time and viewpoint for the two separate instruments. The end result is an awe-inspiring image of the sun and the moon.
Image Credit: NASA/SDO/LRO/GSFC
John Wargo, lead technician at NASA Glenn’s Propulsion System Laboratory (PSL) is performing an inspection on the inlet ducting, upstream of the Honeywell ALF 502 engine that was recently used for the NASA Engine Icing Validation test.
This test allows engine manufacturers to simulate flying through the upper atmosphere where large amounts of icing particles can be ingested and cause flame outs or a loss of engine power on aircraft. This test was the first of its kind in the world and was highly successful in validating PSL’s new capability. No other engine test facility has this capability.
Glenn is working with industry to address this aviation issue by establishing a capability that will allow engines to be operated at the same temperature and pressure conditions experienced in flight, with ice particles being ingested into full scale engines to simulate flight through a deep convective cloud.
The information gained through performing these tests will also be used to establish test methods and techniques for the study of engine icing in new and existing commercial engines, and to develop data required for advanced computer codes that can be specifically applied to assess an engine’s susceptibility to icing in terms of its safety, performance and operability.
Image Credit: NASA
Bridget R. Caswell (Wyle Information Systems, LLC)