Failure of conductance quantization in two-dimensional topological insulators due to non-magnetic impurities

Despite topological protection and the absence of magnetic impurities, two-dimensional topological insulators display quantized conductance only in surprisingly short channels, which can be as short as 100 nm for atomically thin materials. We show that the combined action of short-range nonmagnetic impurities located near the edges and on site electron-electron interactions effectively creates noncollinear magnetic scatterers, and, hence, results in strong backscattering. The mechanism causes deviations from quantization even at zero temperature and for a modest strength of electron-electron interactions. Our theory provides a straightforward conceptual framework to explain experimental results, especially those in atomically thin crystals, plagued with short-range edge disorder.Comment: 8 pages, 9 figures, 5 appendice

Dichotomies in Ontology-Mediated Querying with the Guarded Fragment

We study the complexity of ontology-mediated querying when ontologies are formulated in the guarded fragment of first-order logic (GF). Our general aim is to classify the data complexity on the level of ontologies where query evaluation w.r.t. an ontology O is considered to be in PTime if all (unions of conjunctive) queries can be evaluated in PTime w.r.t. O and coNP-hard if at least one query is coNP-hard w.r.t. O. We identify several large and relevant fragments of GF that enjoy a dichotomy between PTime and coNP, some of them additionally admitting a form of counting. In fact, almost all ontologies in the BioPortal repository fall into these fragments or can easily be rewritten to do so. We then establish a variation of Ladner's Theorem on the existence of NP-intermediate problems and use this result to show that for other fragments, there is provably no such dichotomy. Again for other fragments (such as full GF), establishing a dichotomy implies the Feder-Vardi conjecture on the complexity of constraint satisfaction problems. We also link these results to Datalog-rewritability and study the decidability of whether a given ontology enjoys PTime query evaluation, presenting both positive and negative results

The mesolithic occupation at Isolidda (San Vito Lo Capo), Sicily

‘Gruppo dell’Isolidda’ is a complex of five caves along a rocky cliff on the eastern side of the promontory of San Vito Lo Capo (Trapani) in NW Sicily. In 2004 archaeological excavations in the slope below the caves revealed a stratified deposit, partially in secondary position, containing levels with Late Epigravettian and Mesolithic stone tool assemblages. Early Mesolithic stone tool industries, characterized by backed microlithic tools, were distributed in two contiguous layers (SU 21 and SU 25), the lowest of which (SU 21) also contained Epigravettian tools, probably due to sediment reworking. Three AMS dates on Phorcus turbinatus shells (~9520-8990 cal. BP) are chronologically compatible with the Early Mesolithic materials and suggest that the bulk of the deposit accumulated then. A third level, lying above the previous ones, contained material culture associated to the Late Mesolithic or Early Neolithic. Faunal remains from the site represent mainly food refuse and included abundant shells of intertidal molluscs (e.g. Phorcus turbinatus and Patella sp.), along with few fragmented bones of terrestrial herbivores (e.g. Cervus elaphus and Sus scrofa). Oxygen isotope analyses on shell carbonates of Phorcus turbinatus show that, around 9520-9000 cal. BP, marine molluscs were exploited year-round, albeit more often in autumn and winter

HySenS data exploitation for urban land cover analysis

This paper addresses the use of HySenS airborne hyperspectral data for environmental urban monitoring. It is known that hyperspectral data can help to characterize some of the relations between soil composition, vegetation characteristics, and natural/artificial materials in urbanized areas. During the project we collected DAIS and ROSIS data over the urban test area of Pavia, Northern Italy, though due to a late delivery of ROSIS data only DAIS data was used in this work. Here we show results referring to an accurate characterization and classification of land cover/use, using different supervised approaches, exploiting spectral as well as spatial information. We demonstrate the possibility to extract from the hyperspectral data information which is very useful for environmental characterization of urban areas

Much or More? Experiments of Rationality and Spite with School Children

Copyright © 2014 North American Journal of Pyschology.In a competitive environment the maximization of self-interest and the minimization of the other's interest can be seen as the two faces of the same coin. However, these motivations can lead to very different behaviors. In order to understand how these are expressed, we designed an experiment to measure the ability of children and teenagers to react to stimuli that induce behavior to act as a rational player (maximization of self interest) or as a spiteful player (minimization of other's interest). Each player faced the following dilemma: maximizing pay-off and incurring the risk of having a lower pay-off; or alternatively guaranteeing one’s own pay-off was not smaller than the opponent’s pay-off. A prize was attributed proportionally to the pay-off (Treatment 1) or to the player with highest pay-off (Treatment 2), which meant that the optimal behavior was different for each treatment. We performed experiments with 398 Portuguese children and teenagers and found evidence that younger children tended to be maximizers (in both variants) and that teenagers tended towards rational behavior when it was best for them and towards spiteful behavior when the latter was more advantageous

Patient's reactions to digital rectal examination of the prostate

OBJECTIVE: In recent years, there has been a rise in the incidence of prostate cancer (PCa), and routine screening for the disease has become a well accepted clinical practice. Even with the recognized benefit of this approach, some men are still reluctant to undergo digital rectal examination (DRE). For this reason, we designed the present study in order to better understand men's reactions about this method of screening. The aim was to identify possible drawbacks that could be overcome to increase DRE. MATERIALS AND METHODS: We randomly selected 269 patients that were enrolled in an institutional PCa screening program. They were first asked to answer a question regarding their preferred position to undergo the examination. Following this step, they answered a questionnaire in which physical and psychological reactions regarding the DRE were presented. Finally, we used a visual analogical scale (VAS) to analyze the perception of pain during DRE. RESULTS: The supine position was preferred for most patients (53.9%). Before DRE, about 59.4% of patients felt that the exam would be acceptable. After DRE, this figure increased to 91.5% (p < 0.001). Mean VAS score during DRE was 1.69 on a scale with a range between 0 and 10 (0 = no pain; 10 = extreme pain). CONCLUSION: Patient expectations about DRE were negative before examination and changed significantly following the exam. Pain during examination was negligible, contrary to the prevalent belief. These two findings must be clearly presented to patients in order to improve PCa screening acceptance

Heterologous expression and functional characterization of a GH10 endoxylanase from \u3ci\u3eAspergillus fumigatus\u3c/i\u3e var. \u3ci\u3eniveus\u3c/i\u3e with potential biotechnological application

Xylanases decrease the xylan content in pretreated biomass releasing it from hemicellulose, thus improving the accessibility of cellulose for cellulases. In this work, an endo-β-1,4-xylanase from Aspergillus fumigatus var. niveus (AFUMN-GH10) was successfully expressed. The structural analysis and biochemical characterization showed this AFUMN-GH10 does not contain a carbohydrate-binding module. The enzyme retained its activity in a pH range from 4.5 to 7.0, with an optimal temperature at 60°C. AFUMN-GH10 showed the highest activity in beechwood xylan. The mode of action of AFUMNGH10 was investigated by hydrolysis of APTS-labeled xylohexaose, which resulted in xylotriose and xylobiose as the main products. AFUMN-GH10 released 27% of residual xylan from hydrothermally-pretreated corn stover and 14% of residual xylan from hydrothermally-pretreated sugarcane bagasse. The results showed that environmentally friendly pretreatment followed by enzymatic hydrolysis with AFUMN-GH10 in low concentration is a suitable method to remove part of residual and recalcitrant hemicellulose from biomass