Low-Noise Amplification of a Continuous Variable Quantum State

We present an experimental realization of a low-noise, phase-insensitive optical amplifier using a four-wave mixing interaction in hot Rb vapor. Performance near the quantum limit for a range of amplifier gains, including near unity, can be achieved. Such low-noise amplifiers are essential for so-called quantum cloning machines and are useful in quantum information protocols. We demonstrate that amplification and ``cloning'' of one half of a two-mode squeezed state is possible while preserving entanglement.Comment: To appear in Physical Review Letters July 3rd. 4 pages, 4 figure

Movement Disorders Presenting in Childhood.

PURPOSE OF REVIEW: This article provides an overview of movement disorders that present in childhood. Key clinical features are discussed, and a brief guide to management strategies is provided. Recent advances in the field of pediatric movement disorders are also a focus of the article. RECENT FINDINGS: Advances in genetic technologies and cell biology have contributed greatly to the elucidation of underlying disease mechanisms in childhood movement disorders. This article discusses the expanding spectrum of both genetic and acquired movement disorders that present in childhood, including benign, acquired, genetic, and psychogenic movement disorders. SUMMARY: Movement disorders in childhood comprise a wide spectrum of both genetic and acquired diseases, ranging from benign self-limiting conditions to more progressive phenotypes associated with significant morbidity and mortality. Elucidation of the underlying cause is achieved through accurate history, detailed clinical examination, review of video footage (including home videos), and, where appropriate, neuroimaging and laboratory investigations. Early accurate diagnosis will facilitate the instigation of appropriate management strategies

Magnetic shape-memory effects in La2-xSrxCuO4 crystals

The magnetic field affects the motion of electrons and the orientation of spins in solids, but it is believed to have little impact on the crystal structure. This common perception has been challenged recently by ferromagnetic shape-memory alloys, where the spin-lattice coupling is so strong that crystallographic axes even in a fixed sample are forced to rotate, following the direction of moments. One would, however, least expect any structural change to be induced in antiferromagnets where spins are antiparallel and give no net moment. Here we report on such unexpected magnetic shape-memory effects that take place ironically in one of the best-studied 2D antiferromagnets, La2-xSrxCuO4 (LSCO). We find that lightly-doped LSCO crystals tend to align their b axis along the magnetic field, and if the crystal orientation is fixed, this alignment occurs through the generation and motion of crystallographic twin boundaries. Both resistivity and magnetic susceptibility exhibit curious switching and memory effects induced by the crystal-axes rotation; moreover, clear kinks moving over the crystal surfaces allow one to watch the crystal rearrangement directly with a microscope or even bare eyes.Comment: 3 pages, 4 figures; shortend version of this paper has been published in Nature as a Brief Communicatio

High-contrast approximation for penetrable wedge diffraction

Abstract The important open canonical problem of wave diffraction by a penetrable wedge is considered in the high-contrast limit. Mathematically, this means that the contrast parameter, the ratio of a specific material property of the host and the wedge scatterer, is assumed small. The relevant material property depends on the physical context and is different for acoustic and electromagnetic waves for example. Based on this assumption, a new asymptotic iterative scheme is constructed. The solution to the penetrable wedge is written in terms of infinitely many solutions to (possibly inhomogeneous) impenetrable wedge problems. Each impenetrable problem is solved using a combination of the Sommerfeld–Malyuzhinets and Wiener–Hopf techniques. The resulting approximated solution to the penetrable wedge involves a large number of nested complex integrals and is hence difficult to evaluate numerically. In order to address this issue, a subtle method (combining asymptotics, interpolation and complex analysis) is developed and implemented, leading to a fast and efficient numerical evaluation. This asymptotic scheme is shown to have excellent convergent properties and leads to a clear improvement on extant approaches.</jats:p

Analytical methods for perfect wedge diffraction: A review

© 2019 Elsevier B.V. The subject of diffraction of waves by sharp boundaries has been studied intensively for well over a century, initiated by groundbreaking mathematicians and physicists including Sommerfeld, Macdonald and Poincaré. The significance of such canonical diffraction models, and their analytical solutions, was recognised much more broadly thanks to Keller, who introduced a geometrical theory of diffraction (GTD) in the middle of the last century, and other important mathematicians such as Fock and Babich. This has led to a very wide variety of approaches to be developed in order to tackle such two and three dimensional diffraction problems, with the purpose of obtaining elegant and compact analytic solutions capable of easy numerical evaluation. The purpose of this review article is to showcase the disparate mathematical techniques that have been proposed. For ease of exposition, mathematical brevity, and for the broadest interest to the reader, all approaches are aimed at one canonical model, namely diffraction of a monochromatic scalar plane wave by a two-dimensional wedge with perfect Dirichlet or Neumann boundaries. The first three approaches offered are those most commonly used today in diffraction theory, although not necessarily in the context of wedge diffraction. These are the Sommerfeld–Malyuzhinets method, the Wiener–Hopf technique, and the Kontorovich–Lebedev transform approach. Then follows three less well-known and somewhat novel methods, which would be of interest even to specialists in the field, namely the embedding method, a random walk approach, and the technique of functionally-invariant solutions. Having offered the exact solution of this problem in a variety of forms, a numerical comparison between the exact solution and several powerful approximations such as GTD is performed and critically assessed

What role for the bioeconomy in an electrified transportation sector?

The growth of the bioeconomy has recently been slowed by over production of petroleum and natural gas from unconventional domestic reserves, which has reduced demand for biofuels. In the longer term, liquid transportation fuels, both petroleum- and bio-based, are threatened by electrification of the transportation sector, which will benefit from the use of low-cost natural gas to generate electricity for battery electric vehicles. Low-cost natural gas in the USA is attractive for other applications as well, including the production of certain petrochemicals. On the other hand, natural gas is not suitable for producing many high molecular weight petrochemicals. Cost-competitive biorenewable versions of these products will need to be commercialized if petroleum is to be displaced without causing substantial economic distortions. This article reviews the available bio-based pathways and the current state of research on their technical and, where available, economic feasibility

Monitoring the efficiency of iron chelation therapy: the potential of nontransferrin-bound iron.

The major ligands of nontransferrin-bound iron (NTBI) are suggested to be citrate and albumin. The proportion of iron binding to albumin is influenced by the degree of oxidation and glycation of the protein. LC-ICP-MS is demonstrated to be a useful technique for the speciation of NTBI, with unprocessed serum being subjected to analysis. Ferritin iron, citrate iron, and ferrioxamine can be quantified using this technique. This review describes the use of a new fluorescent probe for NTBI quantification

Primary gastric plasmacytoma: a rare entity

Extramedullary plasmacytomas (EP) are tumours composed by a monoclonal population of plasma cells that arise in extraosseus tissues, comprising <5% of all plasma cell neoplasms. Usually, EP arise in the head and neck region, and the stomach is the second most common location-gastric plasmacytoma (GP). Clinical and radiological manifestations are unspecific and may mimic other tumours like gastric adenocarcinomas, gastric stromal tumours and lymphomas, mainly marginal cell lymphoma (MALT lymphoma) and usually definitive diagnosis is provided by pathological evaluation. We present a case of primary GP, discovered incidentally as a polypoid lesion. Tumour was composed by sheets of mature and immature plasmocytes positive for CD138 on immunohistochemistry, without Helicobacter pylori identification. The patient is alive 6 years later and without tumour relapse.info:eu-repo/semantics/publishedVersio