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### Mathematical Quantum Field Theory – Observables

The following is one chapter in a series on Mathematical Quantum Field Theory. The previous chapter is 6. Symmetries. The next chapter is 8. Phase space 7. Observables Given a Lagrangian field theory (def. 5.4), then a general observable quantity or just observable for short (def. 7.1 below), is a smooth function  A \;\colon\; […]

### Physics Week in Review: November 18, 2017

There's been a flood of cool physics news heading into the Thanksgiving holiday. Some highlights: theory of dark matter disks is toast; LIGO detects yet another binary black hole merger; and the physics of whammy bar resonance. Snap, Crackle, Whop--Explore...

### IEEE International Symposium on Biomedical Imaging 2018

Conference: 4 Apr 2018 - 7 Apr 2018, Washington D.C., United States.

### Excess positrons could come from dark matter after all

HAWC observations discount nearby pulsar sources

### Earth’s body tide hints at deep mantle structure

Flash Physics: need-to-know updates from the world of physics

### Thermal Imaging and Active Thermography seminar

Lecture/talk: 11 Dec 2017, Leatherhead, Surrey, United Kingdom.

### New Research on Untying Knots in Polymers

A joint computational-experimental paper that I worked on was just published in MacroLetters, a journal that covers all topics relating to macromolecules (polymers and the like). In it, we looked at simulations of knotted polymer chains being stretched by an external flow field, and studied how the knot affected the response of the polymer to […]

### Strain-free epitaxy of germanium film on mica

Germanium, an elemental semiconductor, was the material of choice in the early history of electronic devices, before it was largely replaced by silicon. But due to its high charge carrier mobility—higher than silicon by threefold—the semiconductor is making a comeback.

### Researchers reveal jamming in cellular motor protein traffic

To keep a cell alive, molecular motor proteins constantly transport building blocks and waste across the cell, along its biopolymer network. Because of the high density of these proteins, jamming effects are believed to affect this transport, just like traffic jams affect street traffic. Show More Summary

### Researchers tunnel to a new light source

With concerns over moving to a clean energy platform worldwide with electric vehicles and renewables, wasted energy is a factor as important as the amount of green energy produced. Thus, solid-state lighting based upon light-emitting diodes (LEDs) is touted as a solution. Show More Summary

### New imaging technique peers inside living cells

To undergo high-resolution imaging, cells often must be sliced and diced, dehydrated, painted with toxic stains, or embedded in resin. For cells, the result is certain death.

### Arecibo Observatory lives on, but with less money

Flash Physics: need-to-know updates from the world of physics

### Hope fades for axion-like dark matter

Flash Physics: need-to-know updates from the world of physics

### Mathematical Quantum Field Theory – Symmetries

The following is one chapter in a series on Mathematical Quantum Field Theory. The previous chapter is 5. Lagrangians. The next chapter is 7. Observables.   6. Symmetries We have introduced the concept of Lagrangian field theories ##(E,\mathbf{L})## in terms of a field bundle ##E## equipped with a Lagrangian density ##\mathbf{L}## on its jet bundle […]

### Carefully crafted light pulses control neuron activity

Specially tailored, ultrafast pulses of light can trigger neurons to fire and could one day help patients with light-sensitive circadian or mood problems, according to a new study in mice at the University of Illinois.

### Scientists invent technique to map energy and momentum of electrons beneath a material's surface

For the first time, physicists have developed a technique that can peer deep beneath the surface of a material to identify the energies and momenta of electrons there.

### Nano-'hashtags' could be the key to generating the highly sought Majorana quasiparticle

UC Santa Barbara scientists are on the cusp of a major advance in topological quantum computing.

### The stacked color sensor

Red-sensitive, blue-sensitive and green-sensitive color sensors stacked on top of each other instead of being lined up in a mosaic pattern – this principle could allow image sensors with unprecedented resolution and sensitivity to light to be created. Show More Summary

### NIST's next-generation atomic clocks may support official timekeeping

For more than a decade, the National Institute of Standards and Technology (NIST) has been unveiling experimental next-generation atomic clocks. These clocks, based on ytterbium, strontium, aluminum, and mercury atoms, among others, have set records for precision and stability.