Helmholtz bright and boundary solitons

We report, for the first time, exact analytical boundary solitons of a generalized cubic-quintic Non-Linear Helmholtz (NLH) equation. These solutions have a linked-plateau topology that is distinct from conventional dark soliton solutions; their amplitude and intensity distributions are spatially delocalized and connect regions of finite and zero wave-field disturbances (suggesting also the classification as 'edge solitons'). Extensive numerical simulations compare the stability properties of recently-reported Helmholtz bright solitons, for this type of polynomial non-linearity, to those of the new boundary solitons. The latter are found to possess a remarkable stability characteristic, exhibiting robustness against perturbations that would otherwise lead to the destabilizing of their bright-soliton counterpart

Importance of Bacillithiol in the Oxidative Stress Response of Staphylococcus aureus

In Staphylococcus aureus, the low-molecular-weight thiol called bacillithiol (BSH), together with cognate S-transferases, is believed to be the counterpart to the glutathione system of other organisms. To explore the physiological role of BSH in S. aureus, we constructed mutants with the deletion of bshA (sa1291), which encodes the glycosyltransferase that catalyzes the first step of BSH biosynthesis, and fosB (sa2124), which encodes a BSH-S-transferase that confers fosfomycin resistance, in several S. aureus strains, including clinical isolates. Mutation of fosB or bshA caused a 16- to 60-fold reduction in fosfomycin resistance in these S. aureus strains. High-pressure liquid chromatography analysis, which quantified thiol extracts, revealed some variability in the amounts of BSH present across S. aureus strains. Deletion of fosB led to a decrease in BSH levels. The fosB and bshA mutants of strain COL and a USA300 isolate, upon further characterization, were found to be sensitive to H2O2 and exhibited decreased NADPH levels compared with those in the isogenic parents. Microarray analyses of COL and the isogenic bshA mutant revealed increased expression of genes involved in staphyloxanthin synthesis in the bshA mutant relative to that in COL under thiol stress conditions. However, the bshA mutant of COL demonstrated decreased survival compared to that of the parent in human whole-blood survival assays; likewise, the naturally BSH-deficient strain SH1000 survived less well than its BSH-producing isogenic counterpart. Thus, the survival of S. aureus under oxidative stress is facilitated by BSH, possibly via a FosB-mediated mechanism, independently of its capability to produce staphyloxanthin

Wave envelopes with second-order spatiotemporal dispersion : I. Bright Kerr solitons and cnoidal waves

We propose a simple scalar model for describing pulse phenomena beyond the conventional slowly-varying envelope approximation. The generic governing equation has a cubic nonlinearity and we focus here mainly on contexts involving anomalous group-velocity dispersion. Pulse propagation turns out to be a problem firmly rooted in frames-of-reference considerations. The transformation properties of the new model and its space-time structure are explored in detail. Two distinct representations of exact analytical solitons and their associated conservation laws (in both integral and algebraic forms) are presented, and a range of new predictions is made. We also report cnoidal waves of the governing nonlinear equation. Crucially, conventional pulse theory is shown to emerge as a limit of the more general formulation. Extensive simulations examine the role of the new solitons as robust attractors

Wave envelopes with second-order spatiotemporal dispersion: II. Modulational instabilities and dark Kerr solitons

A simple scalar model for describing spatiotemporal dispersion of pulses, beyond the classic “slowly-varying envelopes + Galilean boost” approach, is studied. The governing equation has a cubic nonlinearity and we focus here mainly on contexts with normal group-velocity dispersion. A complete analysis of continuous waves is reported, including their dispersion relations and modulational instability characteristics. We also present a detailed derivation of exact analytical dark solitons, obtained by combining direct-integration methods with geometrical transformations. Classic results from conventional pulse theory are recovered as-ymptotically from the spatiotemporal formulation. Numerical simulations test new theoretical predictions for modulational instability, and examine the robustness of spatiotemporal dark solitons against perturbations to their local pulse shape

Generalized Buneman pruning for inferring the most parsimonious multi-state phylogeny

Accurate reconstruction of phylogenies remains a key challenge in evolutionary biology. Most biologically plausible formulations of the problem are formally NP-hard, with no known efficient solution. The standard in practice are fast heuristic methods that are empirically known to work very well in general, but can yield results arbitrarily far from optimal. Practical exact methods, which yield exponential worst-case running times but generally much better times in practice, provide an important alternative. We report progress in this direction by introducing a provably optimal method for the weighted multi-state maximum parsimony phylogeny problem. The method is based on generalizing the notion of the Buneman graph, a construction key to efficient exact methods for binary sequences, so as to apply to sequences with arbitrary finite numbers of states with arbitrary state transition weights. We implement an integer linear programming (ILP) method for the multi-state problem using this generalized Buneman graph and demonstrate that the resulting method is able to solve data sets that are intractable by prior exact methods in run times comparable with popular heuristics. Our work provides the first method for provably optimal maximum parsimony phylogeny inference that is practical for multi-state data sets of more than a few characters.Comment: 15 page

Evidence For The Production Of Slow Antiprotonic Hydrogen In Vacuum

We present evidence showing how antiprotonic hydrogen, the quasistable antiproton-proton (pbar-p) bound system, has been synthesized following the interaction of antiprotons with the hydrogen molecular ion (H2+) in a nested Penning trap environment. From a careful analysis of the spatial distributions of antiproton annihilation events, evidence is presented for antiprotonic hydrogen production with sub-eV kinetic energies in states around n=70, and with low angular momenta. The slow antiprotonic hydrogen may be studied using laser spectroscopic techniques.Comment: 5 pages with 4 figures. Published as Phys. Rev. Letters 97, 153401 (2006), in slightly different for

Influencia de harinas de yuca y de batata sobre pigmentación, contenido de carotenoides en la yema y desempeño productivo de aves en postura

Se evaluaron ocho dietas iso-energéticas (2.9 Kcal/g) e iso-proteicas (14.5% CP) [(Sin pigmento comercial (t1); pigmento comercial (t2); harina de yuca al 15% (t3); harina de yuca al 30% (t4); harina de batata al 15% (t5); harina de batata al 30% (t6); harina de yuca más harina de batata al 15% cada una (t7) y harina de yuca más harina de batata al 25% cada una (t8)] en un diseño completamente al azar utilizando cuatro réplicas de tres gallinas cada una durante siete periodos experimentales. La concentración de carotenos totales (espectrofotometría UV-visible) presentó deferencias (P and lt;0.01) entre las dietas. La pigmentación (Abanico Roche) y la concentración de carotenos en huevos provenientes de dietas con harinas de yuca y de batata no presentaron diferencias (P and gt;0.05); sí lo hicieron con las dietas testigo (P and lt;0.01). La dieta con pigmento comercial demostró la más alta pigmentación y concentración de carotenoides en yema de huevo. No se observaron diferencias (P and gt;0.05) entre yemas provenientes de dieta sin pigmento y de dietas con harina de yuca y de batata. Luteina, -caroteno, -caroteno, 9-cis--caroteno fueron los más importantes carotenoides encontrados en dietas y en yemas de huevo (HPLC). Cantaxantina solo se encontró en el testigo con pigmento comercial. La concentración fue del 65% del perï¬�l de carotenoides. Luteína fue el principal carotenoide encontrado en yemas mientras que -caroteno fue mayor en las dietas. Las yemas provenientes de dietas con harina de yuca y harina de batata al 15% tuvieron los más altos Equivalentes Retinol de provitamina A. El tipo y componentes del huevo no demostraron diferencias (P and gt;0.05). El desempeño productivo tuvo diferencias (P and lt;0.01). Palabras clave: Manihot esculenta, Ipomoea batatas, Carotenoides, yemas de huevo, vitamina A, harinas.Utilization effect of cassava (Manihot esculenta) and potatoe (Ipomoea batatas) on pigmentation, carotenoids pull on egg yolk and performance yield hens. Eight diets (T1:without pigment, T2: commercial pigment, T3: cassava meal 15%, T4: cassava meal 30%, T5: sweet potato meal 15%, T6: sweet potato meal 30%, T7: cassava and sweet potato meal 15% each, T8: cassava and sweet potato meal 25% each) in a randomized design using four replicates of three hens each during seven experimental periods were evaluated. Diets were iso-energetics (2.9 kcal/g) and iso-proteis (14.5% CP). Carotenoid concentrations (UV-visible chromatography) had differences (P and lt;0.01) among diets. Pigmentation (Fan Roche) and carotenoid concentration in egg yoks to come from cassava and sweet potato diets did not show differences (P and gt;0.05) A comparison with egg yolk to come from test diets signiï¬�cant differences (P and lt;0.01) were detected. Diet with commercial pigment showed the highest pigmentation and carotenoid concentration in egg yolk. The other hand, there saw not differences (P and gt;0.05). A comparison with egg yolk to come from test diets signiï¬�cant differences (P and lt;0.01) were detected. Diet with commercial pigment showed the highest pigmentation and carotenoid concentration in egg yolk. The other hand, there saw not differences (P and gt;0.05) between egg yolk to come from diet without pigment and cassava and sweet potato diets. Lutein, -carotene, -carotene, and 9-cis-- carotene were the most importants carotenoids found in diets and egg yolk (HPLC). Cantoxatin was found in egg yolk and diet with commercial pigment only. Its concentration reached to 65% in proï¬�le carotenes. Lutein was the main carotenoid in egg yolk, while -carotene was the highest in all diets. Egg yolk that come from cassava and sweet potato 15% diet, showed the highest Retinol Equivalent provitamin A. Type and component egg, don¨t showed differences (P and gt;0.05). There were differences (P and lt;0.01) in yield performance.key words: Manihot esculenta, Ipomoea batatas, Carotenoids, egg yolk, vitamin A, meals

Essays on river mechanics

CER92-93-PYJ-5.Presented by the Graduate Students in CE 717 - River Mechanics (Spring 1993).Includes bibliographical references.April 1993

Endometrial carcinoma: molecular alterations involved in tumor development and progression

In the western world, endometrial carcinoma (EC) is the most common cancer of the female genital tract. The annual incidence has been estimated at 10-20 per 100 000 women. Two clinicopathological variants are recognized: the estrogen related (type I, endometrioid) and the non-estrogen related (type II, non-endometrioid).The clinicopathological differences are paralleled by specific genetic alterations, with type I showing microsatellite instability and mutations in phosphatase and tensin homologue deleted on chromosome 70, PIK3CA, K-RAS and CTNNB1 (beta-catenin), and type II exhibiting TP53 mutations and chromosomal instability. Some non-endometrioid carcinomas probably arise from pre-existing endometrioid carcinomas as a result of tumor progression and, not surprisingly, some tumors exhibit combined or mixed features at the clinical, pathological and molecular levels. In EC, apoptosis resistance may have a role in tumor progression. Understanding pathogenesis at the molecular level is essential in identifying biomarkers for successful targeted therapies. In this review, the genetic changes of endometrial carcinogenesis are discussed in the light of the morphological features of the tumors and their precursors

Lineage Divergence and Historical Gene Flow in the Chinese Horseshoe Bat (Rhinolophus sinicus)

PMCID: PMC3581519This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited