Magnetic resonance imaging (MRI) is the medical application of nuclear magnetic resonance spectroscopy and a powerful diagnostic tool.
It works by resonantly exciting hydrogen atoms and measuring the relaxation time -- different materials return to equilibrium at different rates; this is how contrast develops (i.e. between soft and hard tissue). By comparing the measurements to a known spectrum of relaxation times, medical professionals can determine whether the imaged tissue is muscle, bone, or even a cancerous growth.
Although now widely accepted as the most natural explanation of the observed features of the universe around us, dark matter remains a highly mysterious entity to this day. There are literally dozens of possible candidates to explain its nature, wide-ranging in size from subnuclear particles all the way to primordial black holes and beyond. To particle physicists, it is of course natural to assume that dark matter IS a particle, which we have not detected yet. We have a hammer, and that looks like a nail.
There has been discussion among cosmologists about galileons, a hypothetical class of effective scalar fields which are extremely universal and arise generically in describing the short distance behavior of the new degrees of freedom introduced during the process of modifying gravity, and in describing the dynamics of extra dimensional brane worlds. They might be able to explain dark matter - no cosmological constant needed.
Despite prolific use of the term 'theory', they are math that hopes to become physics.
It is a well-known fact that given the availability of food, we eat far more than what would be healthy for our body. Obesity has become a plague in many countries, and the fact that it correlates very tightly with a decreased life expectancy is not a random chance but the demonstrated result of increased risk of life-threatening conditions connected with excess body fat.
Yet we eat, and drink, and eat. We look like self-pleasing monkeys trained to press a button to self-administer a drug. To make matters worse, many of the foods and drinks we consume contain substances purposely added to increase our addiction. So it takes a strong will to control our body weight.
A team of researchers has developed a technique to record the quantum mechanical behavior of an individual electron - contained within a nanoscale defect in diamond.
Their technique uses ultrafast pulses of laser light both to control the defect's entire quantum state and observe how that single electron state changes over time.
This research contributes to the emerging science of quantum information processing, which demands that science leave behind the unambiguous universe of traditional binary logic—0 or 1—and embrace the counterintuitive quantum world, where behavior is radically different from what humans experience every day. While people are generally content being in one place at a time, electrons can be in many states at once.
Today the Cornell arxiv features a paper by J. Aguilar Saavedra and F. Jouaquim
, titled "A closer look at the possible CMS signal of a new gauge boson
". As I read the title I initially felt somewhat lost, as being a CMS member I usually know about the possible new physics signals that my experiment produces, and the fact that we had a possible signal of a new gauge boson had entirely escaped my attention. Hence I downloaded the paper and started reading it, hoping to discover I had discovered something new.
Tomorrow's commercial refrigeration systems, such as those in supermarkets, could be cooled by carbon dioxide instead of hydrofluorocarbons.
Hydrofluorocarbons are a greenhouse gas that is nearly 4,000 times more potent than CO2 and a future with less of them could be important because millions of pounds of HFCs leak into the environment every year, said Brian Fricke, a researcher in Oak Ridge National Laboratory's Building Equipment Research Group.
To address the problem, Fricke and colleagues are experimenting with CO2 and other refrigerants, including a hydrofluoroolefin called R1234yf.
As I reported a couple of times in the course of the last three months, the ATLAS experiment (one of the two all-purpose experiments at the CERN Large Hadron Collider) has launched a challenge to data analyzers around the world
. The task is to correctly classify as many Higgs boson decays to tau lepton pairs as possible, separating them from all competing backgrounds. Those of you who are not familiar with the search of the Higgs boson may wonder what the above means, so here is a crash course on that topic. Crash course on the Higgs and its decays to tau leptons
As a quantum state collapses from a quantum superposition to a classical state or a different superposition, it will follow a path known as a quantum trajectory. For each start and end state there is an optimal or "most likely" path, but it is not as easy to predict the path or track it experimentally as a straight-line between two points would be in our everyday, classical world.
UPDATE III is a rather important one. There is a group at Cambridge which does some similar work to mine. Great minds think alike, I guess. I have posted and revised a few times a paper on my new hypothesis for a theory of gravity which unifies Quantum Mechanics and General Relativity. Whenever someone writes "I have posted and revised a few times a paper on my new hypothesis for a theory of gravity which unifies Quantum Mechanics and General Relativity." The crank alarms should be flashing red alert, but I assure you all Einstein was quite right, but then so was Feynman and those who followed him.
First some background on Quantum Gravity research: