The critical current of disordered superconductors near 0 K

An increasing current through a superconductor can result in a discontinuous increase in the differential resistance at the critical current. This critical current is typically associated either with breaking of Cooper-pairs or with the onset of collective motion of vortices. Here we measure the current–voltage characteristics of superconducting films at low temperatures and high magnetic fields. Using heat-balance considerations we demonstrate that the current–voltage characteristics are well explained by electron overheating enhanced by the thermal decoupling of the electrons from the host phonons. By solving the heat-balance equation we are able to accurately predict the critical currents in a variety of experimental conditions. The heat-balance approach is universal and applies to diverse situations from critical currents to climate change. One disadvantage of the universality of this approach is its insensitivity to the details of the system, which limits our ability to draw conclusions regarding the initial departure from equilibrium

Descemet's membrane detachment management following trabeculectomy

Purpose: To present a case of total Descemet's membrane detachment (DMD) after trabeculectomy and its surgical management. Case Report: A 68-year-old woman presented with large DMD and corneal edema one day after trabeculectomy. Intracameral air injection on day 3 was not effective. Choroidal effusion complicated the clinical picture with Descemet's membrane (DM) touching the lens. Choroidal tap with air injection on day 6 resulted in DM attachment and totally clear cornea on the next day. However, on day 12 the same scenario was repeated with choroidal effusion, shallow anterior chamber (AC), and DM touching the lens. The third surgery included transconjunctival closure of the scleral flap with 10/0 nylon sutures, choroidal tap, and intracameral injection of 20 sulfur hexafluoride. After the third surgery, DM remained attached with clear cornea. Suture removal and needling bleb revision preserved bleb function. Lens opacity progressed, and the patient underwent uneventful cataract surgery 4 months later. Conclusion: Scleral flap closure using transconjunctival sutures can be used for DMD after trabeculectomy to make the eye a closed system. Surgical drainage of choroidal effusions should be considered to increase the AC depth. © 2016 Journal of Ophthalmic and Vision Research

Performance indicators of sheep fed rice straw supplemented with browse leaves

The use of browse leaves as a protein source can help ruminants cope with adverse nutritional stress under unpredictable climatic conditions. The objective of this study was to determine feed intake, digestibility, metabolisable energy intake, weight gain and feed conversion efficiency of sheep fed untreated rice straw supplemented with browse leaves. Four forest type rams with an average weight of 27.75± 0.89 kg (2 years old) and in a replicated 4 x 4 Latin square design were used in the digestibility study. Twelve ram lambs of average weight 13.2 kg ± 0.05 kg were assigned to the experimental diets randomly for 12 weeks in the growth study in a completely randomized design. Animals were fed four diets namely: Untreated rice straw (URS) + Albizzia lebbek (AL) (Control), URS + Moringa oleifera (MO), URS + Ficus exasperata (FE) and URS + Spondias mombin (SM). The dietary treatment influenced (p<0.05) the digestible organic matter in dry matter (DOMD), maintenance energy requirement (MEm), metabolisable energy intake (MEI) and ratio of metabolisable energy intake to maintenance energy requirement (MEI: MEm). The DOMD, MEm, MEI and MEI: MEm were in the range of 965-983/kgDM, 3.61-5.36 MJ/d, 9.51-15.8 MJ/d and 2.63-3.38 respectively. The total intake of browse and straw ranged from 428.71 to 487.14 g/d. The average daily gain ranged from 7.14 to 20.24 g/d. The animals fed URS+FE recorded the highest average daily gain (p<0.05) while the animals fed URS+AL recorded the lowest average daily gain (p<0.05). Feed conversion efficiency ranged from 25.97 to 71.45 kg feed/ kg gain. The sheep fed URS+FE were the most efficient (p<0.05) and those fed URS+AL, the least efficient (p<0.05). Supplementation of browse leaves to sheep using untreated rice straw as a basal diet improved digestibility with moderate weight gains. These browse leaves (AL, FE, MO and SM) can be used to supplement poor quality ruminant diets for improved performance particularly during periods of feed scarcity.&nbsp

AKTIVITAS ANTIOKSIDAN DAN TOKSISITAS EKSTRAK DAUN Coleus Scutellarioides

Coleus scutellarioides merupakan salah satu tanaman yang digunakan untuk mengobati berbagaijenis penyakit di Indonesia. Pada penelitian ini, daun segar diekstraksi dengan pelarut yang berbeda(metanol, etil asetat, diklorometana, dan n-heksana). Semua ekstrak diuji aktivitas antioksidannya denganmenggunakan radikal bebas DPPH. Hasil menunjukkan bahwa ekstrak diklorometana memiliki aktivitasantioksidan yang paling tinggi, diikuti dengan ekstrak etil asetat dengan nilai IC50 masing-masing29,26 dan 67,22 μg/mL. Ekstrak metanol dan n-heksana menunjukkan aktivitas antioksidan yang lemahdengan nilai IC50 > 500 μg/mL. Selain itu, uji toksisitas juga dilakukan pada ekstrak menggunakan BrineShrimp LethalityTest (BSLT). Hasil menunjukkan ekstrak n-heksana memiliki toksisitas yang tinggi diikutidengan ekstrak diklorometana, etil asetat, dan metanol dengan nilai LC50 masing-masing 41,59; 59,93;312,61; dan >500 μg/mL. Oleh karena itu, dapat disimpulkan tanaman ini mengandung senyawa yangmemiliki aktivitas antioksidan dan memiliki toksisitas yang baik sebagai uji pendahuluan antikanker

Diode effect in Josephson junctions with a single magnetic atom

Current flow in electronic devices can be asymmetric with bias direction, a phenomenon underlying the utility of diodes and known as non-reciprocal charge transport. The promise of dissipationless electronics has recently stimulated the quest for superconducting diodes, and non-reciprocal superconducting devices have been realized in various non-centrosymmetric systems. Probing the ultimate limits of miniaturization, we have created atomic-scale Pb--Pb Josephson junctions in a scanning tunneling microscope. Pristine junctions stabilized by a single Pb atom exhibit hysteretic behavior, confirming the high quality of the junctions, but no asymmetry between the bias directions. Non-reciprocal supercurrents emerge when inserting a single magnetic atom into the junction, with the preferred direction depending on the atomic species. Aided by theoretical modelling, we trace the non-reciprocity to quasiparticle currents flowing via Yu-Shiba-Rusinov (YSR) states inside the superconducting energy gap. Our results open new avenues for creating atomic-scale Josephson diodes and tuning their properties through single-atom manipulation

Diode effect in Josephson junctions with a single magnetic atom

Current flow in electronic devices can be asymmetric with bias direction, a phenomenon underlying the utility of diodes1 and known as non-reciprocal charge transport2. The promise of dissipationless electronics has recently stimulated the quest for superconducting diodes, and non-reciprocal superconducting devices have been realized in various non-centrosymmetric systems3,4,5,6,7,8,9,10. Here we investigate the ultimate limits of miniaturization by creating atomic-scale Pb–Pb Josephson junctions in a scanning tunnelling microscope. Pristine junctions stabilized by a single Pb atom exhibit hysteretic behaviour, confirming the high quality of the junctions, but no asymmetry between the bias directions. Non-reciprocal supercurrents emerge when inserting a single magnetic atom into the junction, with the preferred direction depending on the atomic species. Aided by theoretical modelling, we trace the non-reciprocity to quasiparticle currents flowing by means of electron–hole asymmetric Yu–Shiba–Rusinov states inside the superconducting energy gap and identify a new mechanism for diode behaviour in Josephson junctions. Our results open new avenues for creating atomic-scale Josephson diodes and tuning their properties through single-atom manipulation

The Quiescent Emission Spectrum of Cen X-4 and other X-ray Transients containing Neutron Stars

We use the observed optical-UV and X-ray emission spectrum of Cen X-4 during quiescence to constrain models for the accretion flow in this system. We argue that the optical-UV emission is not due to an optically-thick quiescent accretion disk, nor due to synchrotron emission from an Advection-Dominated Accretion Flow (ADAF). Emission from the bright spot could account for the observed optical-UV component if the mass transfer rate in Cen X-4 is >~ 2.10^16 g/s. Although the presence of an ADAF around the neutron star leads to Compton upscattering of the soft X-ray photons radiated from the stellar surface, we find that this process alone cannot account for the power law component seen in the quiescent X-ray spectrum of Cen X-4 and other X-ray transients containing neutron stars; this result is independent of whether the source of soft photons is incandescent thermal emission or accretion-powered emission. We conclude that, in models which invoke the presence of an ADAF and a propeller effect for the quiescence of X-ray transients containing neutron stars, the intrinsic emission from the ADAF must contribute very little to the optical-UV and X-ray emission observed. If these ADAF+propeller models are correct, the X-ray power law component observed must arise from regions where the gas impacts the neutron star surface. Variability studies could greatly help clarify the role of the various emission mechanisms involved.Comment: 10 pages, 3 figures, accepted for publication in Ap

Trace Formulae and Spectral Statistics for Discrete Laplacians on Regular Graphs (I)

Trace formulae for d-regular graphs are derived and used to express the spectral density in terms of the periodic walks on the graphs under consideration. The trace formulae depend on a parameter w which can be tuned continuously to assign different weights to different periodic orbit contributions. At the special value w=1, the only periodic orbits which contribute are the non back- scattering orbits, and the smooth part in the trace formula coincides with the Kesten-McKay expression. As w deviates from unity, non vanishing weights are assigned to the periodic walks with back-scatter, and the smooth part is modified in a consistent way. The trace formulae presented here are the tools to be used in the second paper in this sequence, for showing the connection between the spectral properties of d-regular graphs and the theory of random matrices.Comment: 22 pages, 3 figure

Learning to Control a Brain–Machine Interface for Reaching and Grasping by Primates

Reaching and grasping in primates depend on the coordination of neural activity in large frontoparietal ensembles. Here we demonstrate that primates can learn to reach and grasp virtual objects by controlling a robot arm through a closed-loop brain–machine interface (BMIc) that uses multiple mathematical models to extract several motor parameters (i.e., hand position, velocity, gripping force, and the EMGs of multiple arm muscles) from the electrical activity of frontoparietal neuronal ensembles. As single neurons typically contribute to the encoding of several motor parameters, we observed that high BMIc accuracy required recording from large neuronal ensembles. Continuous BMIc operation by monkeys led to significant improvements in both model predictions and behavioral performance. Using visual feedback, monkeys succeeded in producing robot reach-and-grasp movements even when their arms did not move. Learning to operate the BMIc was paralleled by functional reorganization in multiple cortical areas, suggesting that the dynamic properties of the BMIc were incorporated into motor and sensory cortical representations

Association analysis identifies ZNF750 regulatory variants in psoriasis

<p>Abstract</p> <p>Background</p> <p>Mutations in the <it>ZNF750 </it>promoter and coding regions have been previously associated with Mendelian forms of psoriasis and psoriasiform dermatitis. <it>ZNF750 </it>encodes a putative zinc finger transcription factor that is highly expressed in keratinocytes and represents a candidate psoriasis gene.</p> <p>Methods</p> <p>We examined whether <it>ZNF750 </it>variants were associated with psoriasis in a large case-control population. We sequenced the promoter and exon regions of <it>ZNF750 </it>in 716 Caucasian psoriasis cases and 397 Caucasian controls.</p> <p>Results</p> <p>We identified a total of 47 variants, including 38 rare variants of which 35 were novel. Association testing identified two <it>ZNF750 </it>haplotypes associated with psoriasis (p < 0.05). We also identified an excess of rare promoter and 5'untranslated region (UTR) variants in psoriasis cases compared to controls (p = 0.041), whereas there was no significant difference in the number of rare coding and rare 3' UTR variants. Using a promoter functional assay in stimulated human primary keratinocytes, we showed that four <it>ZNF750 </it>promoter and 5' UTR variants displayed a 35-55% reduction of <it>ZNF750 </it>promoter activity, consistent with the promoter activity reduction seen in a Mendelian psoriasis family with a <it>ZNF750 </it>promoter variant. However, the rare promoter and 5' UTR variants identified in this study did not strictly segregate with the psoriasis phenotype within families.</p> <p>Conclusions</p> <p>Two haplotypes of <it>ZNF750 </it>and rare 5' regulatory variants of <it>ZNF750 </it>were found to be associated with psoriasis. These rare 5' regulatory variants, though not causal, might serve as a genetic modifier of psoriasis.</p