An explicitly solvable model of the spontaneous PT-symmetry breaking

We contemplate the pair of the purely imaginary delta-function potentials on a finite interval with Dirichlet boundary conditions. The two parameter model exhibits nicely the expected quantitative features of the unavoided level crossing and of a "phase-transition" complexification of the energies. Combining analytic and numerical techniques we investigate strength- and position-dependence of its spectrum.Comment: presented in the int. conference "Pseudo-Hermitian Hamiltonians in Quantum Physics III" (Instanbul, Koc University, June 20 - 22, 2005). accepted in Czechoslovak J. Phy

Deep active learning in remote sensing for data efficient change detection

We investigate active learning in the context of deep neural network models for change detection and map updating. Active learning is a natural choice for a number of remote sensing tasks, including the detection of local surface changes: changes are on the one hand rare and on the other hand their appearance is varied and diffuse, making it hard to collect a representative training set in advance. In the active learning setting, one starts from a minimal set of training examples and progressively chooses informative samples that are annotated by a user and added to the training set. Hence, a core component of an active learning system is a mechanism to estimate model uncertainty, which is then used to pick uncertain, informative samples. We study different mechanisms to capture and quantify this uncertainty when working with deep networks, based on the variance or entropy across explicit or implicit model ensembles. We show that active learning successfully finds highly informative samples and automatically balances the training distribution, and reaches the same performance as a model supervised with a large, pre-annotated training set, with ≈99% fewer annotated samples

Human perception of fighting ability: facial cues predict winners in Mixed Martial Arts fights

In antagonistic encounters, the primary decision to be made is to fight or not. Animals may then possess adaptations to assess fighting ability in their opponents. Previous studies suggest that humans can assess strength and fighting ability based on facial appearance. Here we extend these findings to specific contests by examining the perception of male faces from paired winners and losers of individual fights in mixed martial arts sporting competitions. Observers, unfamiliar with the outcome, were presented with image pairs and asked to choose which of the 2 men was more likely to win if they fought while other observers chose between the faces based on masculinity, strength, aggressiveness, and attractiveness. We found that individuals performed at rates above chance in correctly selecting the winner as more likely to win the fight than the loser. We also found that winners were seen to be more masculine, stronger, and more aggressive than losers. Finally, women saw the winners as more attractive than the losers. Together these findings demonstrate that 1) humans can predict the outcome of specific fighting contests based on facial cues, 2) perceived masculinity and strength are putative cues to fighting success available from faces, and 3) facial cues associated with successful male–male competition are attractive to women

Soliton defects in one-gap periodic system and exotic supersymmetry

By applying Darboux-Crum transformations to the quantum one-gap Lame system, we introduce an arbitrary countable number of bound states into forbidden bands. The perturbed potentials are reflectionless and contain two types of soliton defects in the periodic background. The bound states with finite number of nodes are supported in the lower forbidden band by the periodicity defects of the potential well type, while the pulse type bound states in the gap have infinite number of nodes and are trapped by defects of the compression modulations nature. We investigate the exotic nonlinear N=4 supersymmetric structure in such paired Schrodinger systems, which extends an ordinary N=2 supersymmetry and involves two bosonic generators composed from Lax-Novikov integrals of the subsystems. One of the bosonic integrals has a nature of a central charge, and allows us to liaise the obtained systems with the stationary equations of the Korteweg-de Vries and modified Korteweg-de Vries hierarchies. This exotic supersymmetry opens the way for the construction of self-consistent condensates based on the Bogoliubov-de Gennes equations and associated with them new solutions to the Gross-Neveu model. They correspond to the kink or kink-antikink defects of the crystalline background in dependence on whether the exotic supersymmetry is unbroken or spontaneously broken.Comment: 44 pages, 11 figures; comments and refs added, version to appear in Phys. Rev.

Atomic resolution structure of EhpR: phenazine resistance in Enterobacter agglomerans Eh1087 follows principles of bleomycin / mitomycin C resistance in other bacteria

RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are.Abstract Background The phenazines are redox-active secondary metabolites that a large number of bacterial strains produce and excrete into the environment. They possess antibiotic activity owing to the fact that they can reduce molecular oxygen to toxic reactive oxygen species. In order to take advantage of this activity, phenazine producers need to protect themselves against phenazine toxicity. Whereas it is believed that phenazine-producing pseudomonads possess highly active superoxide dismutases and catalases, it has recently been found that the plant-colonizing bacterium Enterobacter agglomerans expresses a small gene ehpR to render itself resistant towards D-alanyl-griseoluteic acid, the phenazine antibiotic produced by this strain. Results To understand the resistance mechanism installed by EhpR we have determined its crystal structure in the apo form at 2.15 Å resolution and in complex with griseoluteic acid at 1.01 Å, respectively. While EhpR shares a common fold with glyoxalase-I/bleomycin resistance proteins, the ligand binding site does not contain residues that some related proteins employ to chemically alter their substrates. Binding of the antibiotic is mediated by π-stacking interactions of the aromatic moiety with the side chains of aromatic amino acids and by a few polar interactions. The dissociation constant KD between EhpR and griseoluteic acid was quantified as 244 ± 45 μM by microscale thermophoresis measurements. Conclusions The data accumulated here suggest that EhpR confers resistance by binding D-alanyl-griseoluteic acid and acting as a chaperone involved in exporting the antibiotic rather than by altering it chemically. It is tempting to speculate that EhpR acts in concert with EhpJ, a transport protein of the major facilitator superfamily that is also encoded in the phenazine biosynthesis operon of E. agglomerans. The low affinity of EhpR for griseoluteic acid may be required for its physiological function.Peer Reviewe

Morphological and ophthalmoscopic features of epiretinal membranes after intravitreal injection of various doses of aflibercept in patients with proliferative diabetic retinopathy

Background: Although methods are available to treat proliferative diabetic retinopathy (PDR), 30% of cases progress, which is an indication for vitrectomy. Purpose: To investigate the ophthalmoscopic and morphological features of epiretinal membranes (ERMs) in patients with PDR depending on the dose of preoperative intravitreal aflibercept (PIA). Material and Methods: Seventy-five patients (75 eyes) with PDR and the presence of fibrovascular ERM with a marked proliferative component were involved in the study. Patients were divided into three groups: eyes of group 1 or control group (31 eyes) received vitrectomy without PIA; group 2 (17 eyes), PIA 1.0 mg; and group 3 (27 eyes), PIA 2.0 mg. We performed a histological study on specimens of fibrovascular ERMs surgically obtained from patients to determine the microscopic features of these membranes. Results: There was ophthalmoscopic and microscopic evidence that aflibercept pretreatment in vitrectomy for PDR resulted in fibrosis of the ERM. The extent of fibrosis of the ERM and obliteration of newly formed blood vessels in the ERM depended on the dose of PIA. Complete obliteration of newly formed blood vessels in the ERM was observed as early as day 3 after 2.0-mg intravitreal aflibercept injection compared to day 5 after 1.0-mg intravitreal aflibercept injection. Pretreatment with 1.0-mg intravitreal aflibercept in vitrectomy for PDR reduced the probability of complications associated with ERM contraction, worsening of the tractional component and the development of a retinal break

Investigating nano-precipitation in a V-containing HSLA steel using small angle neutron scattering

Interphase precipitation (IPP) of nanoscale carbides in a vanadium-containing high-strength low-alloy steel has been investigated. Small angle neutron scattering (SANS) and transmission electron microscopy (TEM) were employed to characterize the precipitates and their size distributions in Fe-0.047C-0.2V-1.6Mn (in wt.%) alloy samples which had been austenitized, isothermally transformed at 700 °C for between 3 and 600 min and water quenched. TEM confirms that, following heat treatment, rows of vanadium-containing nanoscale interphase precipitates were present. Model-independent analysis of the nuclear SANS signal and model fitting calculations, using oblate spheroid and disc-shapes, were performed. The major axis diameter increased from 18 nm after 3 min to 35 nm after 600 min. Precipitate volume percent increased from 0.09 to 0.22 vol% over the same period and number density fell from 2 × 1021 to 5 × 1020 m−3. A limited number of measurements of precipitate maximum diameters from TEM images showed the mean value increased from 8 nm after 5 min to 28 nm after 600 min which is in reasonable agreement with the SANS data