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Comment by Dr. Krishna Kumari Challa on August 3, 2013 at 8:03am

The Physics of Disaster: An Exploration of Train Derailments [Excerpt]

Understanding the science behind trains can help identify the causes of accidents—and lead us to safer railways
http://www.scientificamerican.com/article.cfm?id=the-physics-of-dis...

Everyone knows, or thinks they know, what centrifugal force is. It’s the phenomenon that flings passengers against the car door on a curve, the force that keeps the water in the bucket when swung fast enough overhead, and the force that derails trains on a curve. But centrifugal force can be a source of much confusion because it’s not a force in the traditional sense. Centrifugal force is an inertial effect that occurs when a body in motion changes direction, as in each of the examples above.

Per Isaac Newton, a body in motion tends to stay in motion. If somehow we could eliminate gravity and air resistance, a ball thrown straight up would continue straight up forever. It takes additional force to change the straight-line motion of the ball and to move a train around a curve.

Inertia, the property of matter that resists changes in motion, is most easily explained by accelerating in an elevator. If a 100-lb (0.44-kN) person is standing on a scale in an elevator accelerating up, the scale reads something higher than 100 lbs. If the elevator is accelerating down, the scale reads something less than 100 lbs. If the elevator is accelerating up at 16 ft/sec², or one-half the normal acceleration of gravity, the scale will read 150 lbs (0.66 kN). The extra 50 lbs (0.22 kN) is from the person’s body resisting acceleration.

When a body accelerates, or changes velocity, that acceleration is accompanied by a force. According to Newton’s Second Law, f  m × a. The body’s inertia (m × a) is not a force even though it acts on the scale like a force. The additional 50-lb reading on the scale is the 100-lb person’s resistance to accelerating up 16 ft/sec² (4.9 m/s²)—the person’s inertia.

Inertia always acts in the opposite direction of the acceleration. In the case of the elevator, the person is accelerating up and the inertial response is acting down and is being recorded by the scale. A similar thing happens in circular motion. Circular motion at constant speed creates an acceleration that points toward the center of rotation.

We tend to think of acceleration as being a change in speed (see Chapter 4). Velocity is actually a vector with both direction and magnitude. (The velocity the velocity vector, be it a change in speed or a change in direction, requires a force to create the change. Any change in the velocity vector, be it a change in speed or a change in direction, requires a force to create the change.

Comment by Dr. Krishna Kumari Challa on August 3, 2013 at 8:02am

http://www.scientificamerican.com/article.cfm?id=blue-death-in-worm...
Glowing, Glowing, Gone: Cell Fluorescence Casts Light on How Death Spreads Throughout Body

Researchers have identified a key molecular pathway for animal death that may provide clues for better managing traumatic injury and disease in humans
http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.p...
Anthranilate Fluorescence Marks a Calcium-Propagated Necrotic Wave That Promotes Organismal Death in C. elegans
Abstract

For cells the passage from life to death can involve a regulated, programmed transition. In contrast to cell death, the mechanisms of systemic collapse underlying organismal death remain poorly understood. Here we present evidence of a cascade of cell death involving the calpain-cathepsin necrosis pathway that can drive organismal death in Caenorhabditis elegans. We report that organismal death is accompanied by a burst of intense blue fluorescence, generated within intestinal cells by the necrotic cell death pathway. Such death fluorescence marks an anterior to posterior wave of intestinal cell death that is accompanied by cytosolic acidosis. This wave is propagated via the innexin INX-16, likely by calcium influx. Notably, inhibition of systemic necrosis can delay stress-induced death. We also identify the source of the blue fluorescence, initially present in intestinal lysosome-related organelles (gut granules), as anthranilic acid glucosyl esters—not, as previously surmised, the damage product lipofuscin. Anthranilic acid is derived from tryptophan by action of the kynurenine pathway. These findings reveal a central mechanism of organismal death in C. elegans that is related to necrotic propagation in mammals—e.g., in excitotoxicity and ischemia-induced neurodegeneration. Endogenous anthranilate fluorescence renders visible the spatio-temporal dynamics of C. elegans organismal death.
Author Summary

In the nematode Caenorhabditis elegans, intestinal lysosome-related organelles (or “gut granules”) contain a bright blue fluorescent substance of unknown identity. This has similar spectral properties to lipofuscin, a product of oxidative damage known to accumulate with age in postmitotic mammalian cells. Blue fluorescence seems to increase in aging worm populations, and lipofuscin has been proposed to be the source. To analyze this further, we measure fluorescence levels after exposure to oxidative stress and during aging in individually tracked worms. Surprisingly, neither of these conditions increases fluorescence levels; instead blue fluorescence increases in a striking and rapid burst at death. Such death fluorescence (DF) also appears in young worms when killed, irrespective of age or cause of death. We chemically identify DF as anthranilic acid glucosyl esters derived from tryptophan, and not lipofuscin. In addition, we show that DF generation in the intestine is dependent upon the necrotic cell death cascade, previously characterized as a driver of neurodegeneration. We find that necrosis spreads in a rapid wave along the intestine by calcium influx via innexin ion channels, accompanied by cytosolic acidosis. Inhibition of necrosis pathway components can delay stress-induced death, supporting its role as a driver of organismal death. This necrotic cascade provides a model system to study neurodegeneration and organismal death.

Comment by Dr. Krishna Kumari Challa on August 2, 2013 at 8:41am

http://www.contractlaboratory.com/labclass/outsource_entryform.cfm

Comment by Dr. Krishna Kumari Challa on August 2, 2013 at 8:05am

http://www.scientificamerican.com/article.cfm?id=how-accidents-can-...
Train of Thought Derailed: How an Accident Can Affect Your Brain

A survivor of last week's deadly train derailment in Spain illustrates how disaster can alter your mind

Comment by Dr. Krishna Kumari Challa on August 2, 2013 at 7:10am

http://www.longislandexchange.com/press/2013/07/31/orthobiologics-t...
By definition, orthobiologics is the inclusion of biology and biochemistry in the development of bone and soft tissue replacement materials for skeletal and tissue healing.

Comment by Dr. Krishna Kumari Challa on August 2, 2013 at 7:04am

https://www.researchgate.net/post/Is_the_Protection_of_Research_Ide...,,
Is the Protection of Research Ideas by Intellectual Property Really Worthwhile?

Comment by Dr. Krishna Kumari Challa on August 2, 2013 at 5:44am

http://geology.about.com/cs/odds_and_ends/a/aa070101a.htm?nl=1
The Loch Ness Phenomenon
Natural explanations for the Loch Ness Monster

Comment by Dr. Krishna Kumari Challa on August 2, 2013 at 5:36am

Comment by Georgescu Dan on August 1, 2013 at 10:03pm

Comment by Dr. Krishna Kumari Challa on August 1, 2013 at 6:06am

http://www.scientificamerican.com/article.cfm?id=physicists-debate-...
Physicists Debate Whether the World Is Made of Particles or Fields--or Something Else Entirely [Preview]

Physicists speak of the world as being made of particles and force fields, but it is not at all clear what particles and force fields actually are in the quantum realm. The world may instead consist of bundles of properties, such as color and shape.

It stands to reason that particle physics is about particles, and most people have a mental image of little billiard balls caroming around space. Yet the concept of “particle” falls apart on closer inspection.
Many physicists think that particles are not things at all but excitations in a quantum field, the modern successor of classical fields such as the magnetic field. But fields, too, are paradoxical.
If neither particles nor fields are fundamental, then what is? Some researchers think that the world, at root, does not consist of material things but of relations or of properties, such as mass, charge and spin.

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