Electrons in atoms possess both spin and orbital degrees of freedom. In non-relativistic quantum mechanics, these are independent, resulting in large degeneracies in atomic spectra. However, relativistic effects couple the spin and orbital motion, leading to the well-known fine structure in their spectra. The electronic states in defect-free carbon nanotubes are widely believed to be four-fold degenerate, owing to independent spin and orbital symmetries, and also to possess electron-hole symmetry.

One of key challenges in high-Tc superconductivity research is to identify a predominant mechanism controlling superconductivity at atomic scale.

The problem of reconstructing an object from diffraction data that has been incoherently averaged over a discrete group of symmetries is considered. A necessary condition for such data to uniquely specify the object is derived in terms of the object support and the symmetry group. An algorithm is introduced for reconstructing objects from symmetry-averaged data and its use with simulations is demonstrated.

Background: Insertions and deletions (indels) are an important evolutionary force, making the evolutionary process more efficient and flexible by copying and removing genomic fragments of various lengths instead of rediscovering them by point mutations. As a mutational process, indels are known to be more active in specific sequences (like micro-satellites) but not much is known about the more general and mechanistic effect of sequence context on the insertion and deletion susceptibility of genomic loci.

We present experimental observations of the suppressed superfluid transition temperature, T ca, superfluid fraction, Ï s/Ï and Leggett frequency of 3He-B in aerogel, Ω Ba. We determine T ca from mass decoupling and the vanishing of the frequency shift away from the Larmor frequency in our different samples and different laboratories.

Background. Imaging single cells with fluorescent markers over multiple cell cycles is a powerful tool for unraveling the mechanism and dynamics of the cell cycle. Over the past ten years, microfluidic techniques in cell biology have emerged that allow for good control of growth environment. Yet the control and quantification of transient gene expression in unperturbed dividing cells has received less attention. Methodology/Principal Findings.

To seek the simplest efficient flapping wing motions and understand their relation to steady flight, a two-stroke model in the quasi-steady limit was analyzed. It was found that a family of two-stroke flapping motions have aerodynamic efficiency close to, but slightly lower than, the optimal steady flight. These two-stroke motions share two common features: the downstroke is a gliding motion and the upstroke has an angle of attack close to the optimal of the steady flight of the same wing.

We argue that Coulomb blockade phenomena are a useful probe of the crossover to strong correlation in quantum dots. Through calculations at low density using variational and diffusion quantum Monte Carlo (up to rs ∼55), we find that the addition energy shows a clear progression from features associated with shell structure to those caused by commensurability of a Wigner crystal. This crossover (which occurs near rs ∼20 for spin-polarized electrons) is, then, a signature of interaction-driven localization.

We demonstrate the fabrication and operation of high aspect ratio tensile stressed silicon nitride string resonators. We explore the parameter space of small cross sections, on the order of 100 nm, and long lengths up to 325 μm, demonstrating that such high aspect ratio resonators can be made with standard wet release processing using a material with internal tensile stress. Room temperature quality factors exceed one million at frequencies above 1 MHz.

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