Stationary states of an electron in periodic structures in a constant uniform electrical field

On the basis of the transfer matrix technique an analytical method to investigate the stationary states, for an electron in one-dimensional periodic structures in an external electrical field, displaying the symmetry of the problem is developed. These solutions are shown to be current-carrying. It is also shown that the electron spectrum for infinite structures is continuous, and the corresponding wave functions do not satisfy the symmetry condition of the problem.Comment: 10 pages (Latex), no figures, in the revised variant some mistakes in the English text are corrected and also the first two paragraphs in the Conclusion are refined (Siberian physical-technical institute at the Tomsk state university, Tomsk, Russia

Using state space differential geometry for nonlinear blind source separation

Given a time series of multicomponent measurements of an evolving stimulus, nonlinear blind source separation (BSS) seeks to find a "source" time series, comprised of statistically independent combinations of the measured components. In this paper, we seek a source time series with local velocity cross correlations that vanish everywhere in stimulus state space. However, in an earlier paper the local velocity correlation matrix was shown to constitute a metric on state space. Therefore, nonlinear BSS maps onto a problem of differential geometry: given the metric observed in the measurement coordinate system, find another coordinate system in which the metric is diagonal everywhere. We show how to determine if the observed data are separable in this way, and, if they are, we show how to construct the required transformation to the source coordinate system, which is essentially unique except for an unknown rotation that can be found by applying the methods of linear BSS. Thus, the proposed technique solves nonlinear BSS in many situations or, at least, reduces it to linear BSS, without the use of probabilistic, parametric, or iterative procedures. This paper also describes a generalization of this methodology that performs nonlinear independent subspace separation. In every case, the resulting decomposition of the observed data is an intrinsic property of the stimulus' evolution in the sense that it does not depend on the way the observer chooses to view it (e.g., the choice of the observing machine's sensors). In other words, the decomposition is a property of the evolution of the "real" stimulus that is "out there" broadcasting energy to the observer. The technique is illustrated with analytic and numerical examples.Comment: Contains 14 pages and 3 figures. For related papers, see http://www.geocities.com/dlevin2001/ . New version is identical to original version except for URL in the bylin

Direct evidence for the magnetic ordering of Nd ions in NdFeAsO by high resolution inelastic neutron scattering

We investigated the low energy excitations in the parent compound NdFeAsO of the Fe-pnictide superconductor in the $\mu$eV range by a back scattering neutron spectrometer. The energy scans on a powder NdFeAsO sample revealed inelastic peaks at E = 1.600 $\pm 0.003 \mu$eV at T = 0.055 K on both energy gain and energy loss sides. The inelastic peaks move gradually towards lower energy with increasing temperature and finally merge with the elastic peak at about 6 K. We interpret the inelastic peaks to be due to the transition between hyperfine-split nuclear level of the $^{143}$Nd and $^{145}$Nd isotopes with spin $I = 7/2$. The hyperfine field is produced by the ordering of the electronic magnetic moment of Nd at low temperature and thus the present investigation gives direct evidence of the ordering of the Nd magnetic sublattice of NdFeAsO at low temperature

The recoverability of fingerprints on paper exposed to elevated temperatures - Part 2: natural fluorescence

Previous work by the authors [1] investigated the recoverability of fingerprints on paper which had been exposed to elevated temperatures by comparing various chemical enhancement techniques (ninhydrin, 1,8-diazafluoren-9-one (DFO), and physical developer (PD)). During that study, it became apparent, as a consequence of observations made in operational work [2], that fingerprints on paper subjected to 150˚C fluoresced under examination with green light of waveband 473-548nm with a 549nm viewing filter. This work examined the three types of prints (eccrine, sebaceous, and ungroomed) after 20 min exposure to the temperature range 110˚C to 190˚C (in 10˚C increments) and found that the eccrine fingerprints fluoresced more brightly. This indicated that it was a component of the eccrine deposit which was causing the fluorescence. Luminance measurements found that the maximum fluorescence was experienced at 170˚C on both types of paper. As a consequence, eccrine heat-treated fingerprints were viewed under violet-blue (350-469nm), blue (352-509nm), and green light (473-548nm) which indicated that the greatest luminance intensities were obtained under blue light and the smallest under green light. In order to determine what component of the eccrine fingerprint was causing this fluorescence, five of the most prevalent amino acids (alanine, aspartic acid, glycine, lysine, and serine) [3-4] were exposed to this temperature range. The luminance measurements were taken under exposure to the green light in order for the minimum fluorescence to be observed, with an assumption that blue-violet or blue illumination will provide brighter fluorescence in practice. The results indicated that four of the amino acids are behaving similarly across the temperature range, but with slightly different luminance measurements, but all are exhibiting some level of fluorescence. Thermal degradation products of alanine and aspartic acid have been suggested by Richmond-Aylor et al. [5]. The structure of these thermal degradation products is cyclic in nature, and as such, there is a possibility that two of these products would fluorescence. Sodium chloride and urea were also exposed to the temperature range and they also fluoresced to some extent. This work shows that eccrine fingerprints that have been exposed to temperatures of between 130˚C to 180˚C will fluoresce under violet-blue, blue, and green light. This level of fluorescence for ungroomed fingerprints is much less but this will be dependent on the individual, the more eccrine the deposit, the stronger the fluorescence. This work shows that the amino acids, sodium chloride, and urea present in fingerprint deposits are all contributing to the fluorescence of the print, but may not be the sole contributor as other eccrine components have not yet been tested

Effects of Process Variables and Size Scale on Solidification Microstructure in Laser-Based Solid Freeform Fabrication of Ti-6Al-4V

Mechanical Engineerin

The Love in Loving: Overcoming Artificial Racial Barriers

The rewritten opinion of Loving v. Virginia in Feminist Judgments: Rewritten Opinions of the United States Supreme Court is in stark contrast to the original. Professor Teri McMurtry-Chubb’s judgment for the court “unmasks—and renders unavoidable— the link between America’s history of White supremacy and patriarchy and America’s legal structures for regulating marriage and families.” The feminist opinion relies almost entirely on legal, social, and cultural history, in particular the history of marriage and family relationships among and between Blacks and Whites during the colonial, antebellum, and postbellum eras in the American South. For the authors of this response Essay, both the original and rewritten Loving opinions get it right by focusing on White supremacy, but they fall short in treating Mildred and Richard as proxies for racial justice. In their view, it is important for the law to remember that Mildred and Richard were real people, whose lives depended on the outcome of this case. The authors also reflect on the future of what they identify as artificial racial barriers. In emphasizing that Mildred Jeter identified as mixed race, the authors highlight the difficulty of racial categorization in the modern era when so many are discovering, sometimes surprisingly, their mixed and diverse ancestry. Thus, the Essay suggests, while the rewritten feminist judgment might have worked some societal change through the development of the law, time and culture are equally powerful agents of change

Obesity-induced changes in lipid mediators persist after weight loss.

BackgroundObesity induces significant changes in lipid mediators, however, the extent to which these changes persist after weight loss has not been investigated.Subjects/methodsWe fed C57BL6 mice a high-fat diet to generate obesity and then switched the diet to a lower-fat diet to induce weight loss. We performed a comprehensive metabolic profiling of lipid mediators including oxylipins, endocannabinoids, sphingosines and ceramides in key metabolic tissues (including adipose, liver, muscle and hypothalamus) and plasma.ResultsWe found that changes induced by obesity were largely reversible in most metabolic tissues but the adipose tissue retained a persistent obese metabolic signature. Prostaglandin signaling was perturbed in the obese state and lasting increases in PGD2, and downstream metabolites 15-deoxy PGJ2 and delta-12-PGJ2 were observed after weight loss. Furthermore expression of the enzyme responsible for PGD2 synthesis (hematopoietic prostaglandin D synthase, HPGDS) was increased in obese adipose tissues and remained high after weight loss. We found that inhibition of HPGDS over the course of 5 days resulted in decreased food intake in mice. Increased HPGDS expression was also observed in human adipose tissues obtained from obese compared with lean individuals. We then measured circulating levels of PGD2 in obese patients before and after weight loss and found that while elevated relative to lean subjects, levels of this metabolite did not decrease after significant weight loss.ConclusionsThese results suggest that lasting changes in lipid mediators induced by obesity, still present after weight loss, may play a role in the biological drive to regain weight

Evaluation of the Effects of a Plasma Activated Medium on Cancer Cells

The interaction of low temperature plasma with liquids is a relevant topic of study to the field of plasma medicine. This is because cells and tissues are normally surrounded or covered by biological fluids. Therefore, the chemistry induced by the plasma in the aqueous state becomes crucial and usually dictates the biological outcomes. This process became even more important after the discovery that plasma activated media can be useful in killing various cancer cell lines. Here, we report on the measurements of concentrations of hydrogen peroxide, a species known to have strong biological effects, produced by application of plasma to a minimum essential culture medium. The activated medium is then used to treat SCaBER cancer cells. Results indicate that the plasma activated medium can kill the cancer cells in a dose dependent manner, retain its killing effect for several hours, and is as effective as apoptosis inducing drugs