Kohn-Sham potential with discontinuity for band gap materials

We model a Kohn-Sham potential with a discontinuity at integer particle numbers derived from the GLLB approximation of Gritsenko et al. We evaluate the Kohn-Sham gap and the discontinuity to obtain the quasiparticle gap. This allows us to compare the Kohn-Sham gaps to those obtained by accurate many-body perturbation theory based optimized potential methods. In addition, the resulting quasiparticle band gap is compared to experimental gaps. In the GLLB model potential, the exchange-correlation hole is modeled using a GGA energy density and the response of the hole to density variations is evaluated by using the common-denominator approximation and homogeneous electron gas based assumptions. In our modification, we have chosen the PBEsol potential as the GGA to model the exchange hole, and add a consistent correlation potential. The method is implemented in the GPAW code, which allows efficient parallelization to study large systems. A fair agreement for Kohn-Sham and the quasiparticle band gaps with semiconductors and other band gap materials is obtained with a potential which is as fast as GGA to calculate.Comment: submitted to Physical Review

The quantum phase slip phenomenon in superconducting nanowires with high-impedance environment

Quantum phase slip (QPS) is the particular manifestation of quantum fluctuations of the order parameter of a current-biased quasi-1D superconductor. The QPS event(s) can be considered a dynamic equivalent of tunneling through conventional Josephson junction containing static in space and time weak link(s). At low temperatures T<<Tc the QPS effect leads to finite resistivity of narrow superconducting channels and suppresses persistent currents in tiny nanorings. Here we demonstrate that the quantum tunneling of phase may result in Coulomb blockade: superconducting nanowire, imbedded in high-Ohmic environment, below a certain bias voltage behaves as an insulator.Comment: 3 pages, 3 figure

The two phases of core formation : orbital evolution in the centres of ellipticals with supermassive black hole binaries

The flat stellar density cores of massive elliptical galaxies form rapidly due to sinking supermassive black holes (SMBHs) in gas-poor galaxy mergers. After the SMBHs form a bound binary, gravitational slingshot interactions with nearby stars drive the core regions towards a tangentially biased stellar velocity distribution. We use collisionless galaxy merger simulations with accurate collisional orbit integration around the central SMBHs to demonstrate that the removal of stars from the centre by slingshot kicks accounts for the entire change in velocity anisotropy. The rate of strong (unbinding) kicks is constant over several hundred Myr at similar to 3 M-circle dot yr(-1) for our most massive SMBII binary (M-BH = 1.7 x 10(10) M-circle dot). Using a frequency-based orbit classification scheme (box, x-tube, z-tube, rosette), we demonstrate that slingshot kicks mostly affect box orbits with small pericentre distances, leading to a velocity anisotropy of beta less than or similar to -0.6 within several hundred Myr as observed in massive ellipticals with large cores. We show how different SMBH masses affect the orbital structure of the merger remnants and present a kinematic tomography connecting orbit families to integral field kinematic features. Our direct orbit classification agrees remarkably well with a modern triaxial Schwarzschild analysis applied to simulated mock kinematic maps.Peer reviewe

Transgenerational Effects of Heavy Metal Pollution on Immune Defense of the Blow Fly Protophormia terraenovae

Recently environmental conditions during early parental development have been found to have transgenerational effects on immunity and other condition-dependent traits. However, potential transgenerational effects of heavy metal pollution have not previously been studied. Here we show that direct exposure to heavy metal (copper) upregulates the immune system of the blow fly, Protophormia terraenovae, reared in copper contaminated food. In the second experiment, to test transgenerational effects of heavy metal, the parental generation of the P. terraenovae was reared in food supplemented with copper, and the immunocompetence of their offspring, reared on uncontaminated food, was measured. Copper concentration used in this study was, in the preliminary test, found to have no effect on mortality of the flies. Immunity was tested on the imago stage by measuring encapsulation response against an artificial antigen, nylon monofilament. We found that exposure to copper during the parental development stages through the larval diet resulted in immune responses that were still apparent in the next generation that was not exposed to the heavy metal. We found that individuals reared on copper-contaminated food developed more slowly compared with those reared on uncontaminated food. The treatment groups did not differ in their dry body mass. However, parental exposure to copper did not have an effect on the development time or body mass of their offspring. Our study suggests that heavy metal pollution has positive feedback effect on encapsulation response through generations which multiplies the harmful effects of heavy metal pollution in following generations

Antimicrobial resistance in Staphylococcus spp., Escherichia coli and Enterococcus spp. in dogs given antibiotics for chronic dermatological disorders, compared with non-treated control dogs

The aim of this study was to evaluate antimicrobial resistance in canine staphylococci, Escherichia coli and enterococci, which were isolated from 22 dogs with pyoderma and a history of previous antibiotic treatment, compared to bacterial isolates from 56 non-treated control dogs. Two isolates of each bacterial species per dog were investigated, if detected. Staphylococcal isolates from dogs with pyoderma (35 isolates) were more resistant to sulphatrimethoprim than the isolates from controls (56 isolates) (57% vs. 25%, p < 0.004). Multiresistance in staphylococci was also more common in dogs with pyoderma (29% vs. 9%, p = 0.02). A similar trend among isolates of E. coli was detected (24 and 74 isolates from treated and control dogs, respectively), but the differences were not significant. Resistance for macrolide-lincosamides was approximately 20% among staphylococci in both groups. Resistance to ampicillin among enterococci was 4%–7%. The age of the dogs might have an impact on resistance: multiresistance among staphylococcal isolates from younger dogs (≤5 years) was more common than in older dogs (≥6 years) (24%, vs. 0%, 63 and 27 isolates, respectively, p = 0.02). Staphylococci in younger dogs were more resistant to tetracycline (48% vs. 11%, p < 0.001) and sulphatrimethoprim (48% vs. 15%, p < 0.01) than those in older dogs. In contrast, the isolates of E. coli from older dogs tended to be more resistant, although a significant difference was detected only in resistance to tetracycline (13% vs. 2% of 40 and 50 isolates respecthely, p = 0.04)). The results of this small study indicate that resistance in canine staphylococci in the capital area of Finland is comparable with many other countries in Europe. Resistance in indicator bacteria, E. coli and enterococci, was low

Personalized drug sensitivity screening for bladder cancer using conditionally reprogrammed patient-derived cells

Many patients with muscle-invasive bladder cancer (BC) are either ineligible for or do not benefit from cisplatin-based chemotherapy, and there is an unmet need to estimate individuals’ drug sensitivities. We investigated the suitability of conditionally reprogrammed (CR) cells for the characterization of BC properties and their feasibility for personalized drug sensitivity screening. The CR cultures were established from six BC tumors with varying histology and stage. Four cultures were successfully propagated for genomic, transcriptomic, and protein expression profiling and compared to the parental tumors. Two out of four CR cultures (urothelial carcinoma and small cell neuroendocrine carcinoma [SmCC]) corresponded well to their parental tumors and underwent drug sensitivity screening to identify novel drugs for the respective tumors. Both cultures were sensitive to standard BC chemotherapy agents (eg cisplatin and gemcitabine) and to conventional drugs such as taxanes and inhibitors of topoisomerase and proteasome. The SmCC cells were also sensitive to statins (eg, atorvastatin and pitavastatin). In summary, after confirming their representativeness and origin, we conclude that CR cells are a feasible platform for personalized drug sensitivity testing and might thus add to the approaches used to personalize BC treatment strategies

Annual cycle of volatile organic compound exchange between a boreal pine forest and the atmosphere

Long-term flux measurements of volatile organic compounds (VOC) over boreal forests are rare, although the forests are known to emit considerable amounts of VOCs into the atmosphere. Thus, we measured fluxes of several VOCs and oxygenated VOCs over a Scots-pine-dominated boreal forest semi-continuously between May 2010 and December 2013. The VOC profiles were obtained with a proton transfer reaction mass spectrometry, and the fluxes were calculated using vertical concentration profiles and the surface layer profile method connected to the Monin-Obukhov similarity theory. In total fluxes that differed significantly from zero on a monthly basis were observed for 13 out of 27 measured masses. Monoterpenes had the highest net emission in all seasons and statistically significant positive fluxes were detected from March until October. Other important compounds emitted were methanol, ethanol+ formic acid, acetone and isoprene+ methylbutenol. Oxygenated VOCs showed also deposition fluxes that were statistically different from zero. Isoprene+ methylbutenol and monoterpene fluxes followed well the traditional isoprene algorithm and the hybrid algorithm, respectively. Emission potentials of monoterpenes were largest in late spring and autumn which was possibly driven by growth processes and decaying of soil litter, respectively. Conversely, largest emission potentials of isoprene+ methylbutenol were found in July. Thus, we concluded that most of the emissions of m/z 69 at the site consisted of isoprene that originated from broadleaved trees. Methanol had deposition fluxes especially before sunrise. This can be connected to water films on surfaces. Based on this assumption, we were able to build an empirical algorithm for bi-directional methanol exchange that described both emission term and deposition term. Methanol emissions were highest in May and June and deposition level increased towards autumn, probably as a result of increasing relative humidity levels leading to predominance of deposition.Peer reviewe

Band offset determination of the GaAs/GaAsN interface using the DFT method

The GaAs/GaAsN interface band offset is calculated from first principles. The electrostatic potential at the core regions of the atoms is used to estimate the interface potential and align the band structures obtained from respective bulk calculations. First, it is shown that the present method performs well on the well-known conventional/conventional AlAs/GaAs (001) superlattice system. Then the method is applied to a more challenging nonconventional/conventional GaAsN/GaAs (001) system, and consequently type I band lineup and valence-band offset of about 35 meV is obtained for nitrogen concentration of about 3 %, in agreement with the recent experiments. We also investigate the effect of strain on the band lineup. For the GaAsN layer longitudinally strained to the GaAs lattice constant, the type II lineup with a nearly vanishing band offset is found, suggesting that the anisotropic strain along the interface is the principal cause for the often observed type I lineup

Genetic resistance determinants to fusidic acid and chlorhexidine in variably susceptible staphylococci from dogs

Abstract Background Concern exists that frequent use of topically-applied fusidic acid (FA) and chlorhexidine (CHX) for canine pyoderma is driving clinically relevant resistance, despite rare description of FA and CHX genetic resistance determinants in canine-derived staphylococci. This study aimed to determine minimum inhibitory concentrations (MICs) and investigate presence of putative resistance determinants for FA and CHX in canine-derived methicillin-resistant (MR) and -susceptible (MS) staphylococci. Plasmid-mediated resistance genes (fusB, fusC, fusD, qacA/B, smr; PCR) and MICs (agar dilution) of FA and CHX were investigated in 578 staphylococci (50 MR S. aureus [SA], 50 MSSA, 259 MR S. pseudintermedius [SP], 219 MSSP) from Finland, U.S.A., North (NUK) and South-East U.K. (SEUK) and Germany. In all isolates with FA MIC ≥64 mg/L (n = 27) fusA and fusE were amplified and sequenced. Results FA resistance determinants (fusA mutations n = 24, fusB n = 2, fusC n = 36) were found in isolates from all countries bar U.S.A. and correlated with higher MICs (≥1 mg/L), although 4 SP isolates had MICs of 0.06 mg/L despite carrying fusC. CHX MICs did not correlate with qacA/B (n = 2) and smr (n = 5), which were found in SEUK SA, and SP from NUK and U.S.A. Conclusions Increased FA MICs were frequently associated with fusA mutations and fusC, and this is the first account of fusB in SP. Despite novel description of qacA/B in SP, gene presence did not correlate with CHX MIC. Selection pressure from clinical use might increase prevalence of these genetic determinants, but clinical significance remains uncertain in relation to high skin concentrations achieved by topical therapy