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In a Type II superconductor, the vortex core behaves like a normal metal. Consequently, the single-particle density of states in the vortex core of a conventional Type II superconductor remains either flat or (for very clean single crystals) exhibits a peak at zero bias due to the formation of Caroli-de Gennes-Matricon bound state inside the core. Here we report an unusual observation from scanning tunneling spectroscopy measurements in a weakly pinned thin film of the conventional s-wave superconductor a-MoGe, namely, that a soft gap in the local density of states continues to exist even at the center of the vortex core. We ascribe this observation to rapid fluctuation of vortices about their mean position that blurs the boundary between the gapless normal core and the gapped superconducting region outside. Analyzing the data as a function of magnetic field we show that the variation of fluctuation amplitude as a function of magnetic field is consistent with quantum zero-point motion of vortices., arXiv admin note: substantial text overlap with arXiv:1905.01045

The highly convergent form of superfluid density in disordered conventional superconductors available in the literature and independently obtained by us following the approach of an earlier paper [Phys. Rev. B $\bm{102}$, 024514 (2020)] has been reformulated to separate out the generally used so-called `dirty-limit' term and an additional term. We use this new expression for making an extensive comparison with previously published experimental data and show that the former, generally used, term is {\em not} sufficient for analyzing these results. We point out that consequently, there is a large regime (disordered superconductors with moderate to no disorder) where theoretical predictions need to be confronted with experiment., Comment: 8 pages, 3 figures

In two-dimensional (2D) systems, the melting from a solid to an isotropic liquid can occur via an intermediate phase that retains orientational order. However, in 2D superconducting vortex lattices, the effect of orientational correlations on transport, and their interplay with disorder remain open questions. Here we study a 2D weakly pinned vortex system in amorphous MoGe films over an extensive range of temperatures ($\bm{T}$) and perpendicular magnetic fields ($\bm{H}$) using linear and nonlinear transport measurements. We find that, at low fields, the resistivity obeys the Vogel-Fulcher-Tamman (VFT) form, $\bm{\rho(T)\propto\exp[-{W}(H)/(T-T_0(H))]}$, characteristic of fragile glasses. As $\bm{H}$ increases, $\bm{T_0(H)}$ is suppressed to zero, and a standard vortex liquid behavior consistent with a $\bm{T=0}$ superconducting transition is observed. Our findings, supported also by simulations, suggest that the presence of orientational correlations gives rise to a heterogeneous dynamics responsible for the VFT behavior. The effects of quenched disorder become dominant at high $\bm{H}$, where a crossover to a strong-glass behavior is observed. This is a new insight into the dynamics of melting in 2D systems with competing orders., Comment: 16 pages, 12 figures

Adequate calcium intake is important for the prevention of bone loss and osteoporosis. For some populations such as those of Southeast Asia where calcium intake is very low, supplements represent a suitable dietary source of calcium. The objective of this study was to compare the relative oral bioavailability of calcium from calcium glucoheptonate, a highly soluble calcium salt containing 8.2% of elemental calcium, to that of calcium carbonate. A single‐dose, randomized‐sequence, open‐label, two‐period crossover study, with a 7‐day washout period, was conducted in 24 Indonesian healthy adult volunteers. After a 12‐hour (overnight) fast, subjects received either two oral ampoules of 250 mg/10 mL of calcium glucoheptonate each or one effervescent tablet of calcium carbonate containing 500 mg of elemental calcium. The relative oral bioavailability of calcium from calcium glucoheptonate as compared to calcium carbonate was 92% within 6 hours and 89% within 12 hours after study drug administration. The 90% confidence intervals for the mean test/reference ratios of the maximum plasma concentration and the area under the concentration‐time curve at 12 hours post‐administration were 77.09%–120.31% and 60.58%–122.30%, respectively. Five subjects experienced a total of eight adverse events which were all mild and transient; no serious adverse events or deaths were reported. These results indicate that calcium glucoheptonate is associated with a high relative bioavailability of calcium compared to calcium carbonate, and is well‐tolerated. Calcium glucoheptonate might thus be a potential choice for calcium supplementation in Southeast Asian populations.

Superconductivity occurs in metals when attractive interactions between electrons promote the formation of Cooper pairs which get locked in a phase-coherent state, leading to superfluid behavior. In situations where the phase stiffness falls below the pairing energy, the superconducting transition temperature ${T}_{c}$ is driven by phase fluctuations and pairing can continue to survive above ${T}_{c}$. Such a behavior has long been thought of as the hallmark of unconventional superconductivity. Here we combine sub-K scanning tunneling spectroscopy, magnetic penetration depth measurements, and magnetotransport measurements to show that in ultrathin amorphous MoGe ($a$-MoGe) films the superfluid density is strongly suppressed by quantum phase fluctuations at low temperatures for thickness below 5 nm. This is associated with a rapid decrease in the superconducting transition temperature ${T}_{c}$ and the emergence of a pronounced pseudogap above ${T}_{c}$. These observations suggest that even in conventional superconductors strong disorder and low dimensionality will ultimately trigger a Bosonic route for the destruction of superconductivity.

We report the growth, characterization and superconducting properties of a new amorphous superconductor, RexZr ( x ~ 6 ), in thin film form. Films were grown by pulsed laser deposition with the substrate kept at room temperature. Films with thickness larger than 40 nm showed a superconducting transition temperature (Tc) of 5.9 K. Superconducting properties were measured for films with varying thickness from 120 to 3 nm. The normal state resistance scales linearly with inverse of thickness. The transition temperature, critical field, coherence length, penetration depth and superconducting energy gap changes marginally with decreasing film thickness down to 8 nm. Scanning tunneling spectroscopy and penetration depth measurements provide evidence for a single gap strong coupling s-wave superconductor. Magneto-transport properties indicate a rich magnetic field-temperature phase diagram with the possibility of vortex liquid phases existing over a large fraction of the mixed state.

Recently, detailed real space imaging using scanning tunneling spectroscopy of the vortex lattice in a weakly pinned a-MoGe thin film revealed that the vortex lattice melts in two steps with temperature or magnetic field, going first from a vortex solid to a hexatic vortex fluid and then from a hexatic vortex fluid to an isotropic vortex liquid. In this paper, we show that the resistance in the vortex fluid states is extremely sensitive to radio-frequency electromagnetic perturbation. In the presence of very low-amplitude excitation above few kilohertz, the resistance increases by several orders of magnitude. On the other hand when the superconductor is well shielded from external electromagnetic radiation, the dissipation in the sample is very small and the resistance is below our detection limit., pdf file with figures

Pinning and creep determine the current--voltage characteristic of a type II superconductor and thereby its potential for technological applications. The recent development of strong pinning theory provides us with a tool to assess a superconductor's electric properties in a quantitative way. Motivated by the observation of typical excess-current characteristics and field-scaling of critical currents, here, we analyze current--voltage characteristics measured on 2H-NbSe$_2$ and $a$-MoGe type II superconductors within the setting provided by strong pinning theory. The experimentally observed shift and rounding of the voltage-onset is consistent with the predictions of strong pinning in the presence of thermal fluctuations. We find the underlying parameters determining pinning and creep and discuss their consistency.

The Alaknanda River is the most significant parental river of Ganga and forms an 11.5 km long and 2.5 km wide valley, locally known as the Srinagar Valley. The purpose of the present study is to highlight the recent landform changes in the Alaknanda channel course after the Kedarnath disaster, 2013. The Kedarnath flood completely changed the channel morphology of the Alaknanda river. The river changed its course at Srikot, SSB and Sriyantra Tapu with lower terraces being silted by sands at Ranihat, SSB, Bhaktiyana and Sriyantra Tapu. A new depositional terrace also formed opposite to Sriyantra Tapu. New lateral channel bars, braided channels, back swamp, rapids, pools and river souls were identified in the channel course of the river. Shifting of the channel course at Chauras still remains a serious problem for the Garhwal University Chauras Campus. About 2–5 m silt was deposited on the lower terrace at SSB, and ITI. The Srikot river bed was appended to 4.60 m. Shifting of channel course remains a serious threat to the Srinagar valley. Urbanization, sand and boulders mining, construction of dam, hydrological canal, road and settlements are the prominent example of anthropogenic activities which affect the shifting channel.

Within the Bardeen–Cooper–Schrieffer (BCS) theory, superconductivity is entirely governed by the pairing energy scale, which gives rise to the superconducting energy gap, Δ. However, another important energy scale, the superfluid phase stiffness, J, which determines the resilience of the superconductor to phase-fluctuations is normally ignored. The spectacular success of BCS theory owes to the fact that in conventional superconductors J is normally several orders of magnitude larger than Δ and thus an irrelevant energy scale. However, in certain situations such as in the presence of low carrier density, strong disorder, at low-dimensions or in granular superconductors, J can drastically come down and even become smaller than Δ. In such situations, the temperature and magnetic field evolution of superconducting properties is governed by phase fluctuations, which gives rise to novel electronic states where signatures of electronic pairing continue to exist even when the zero resistance state is destroyed. In this article, we will review the recent experimental developments on the study of phase fluctuations in conventional superconductors.

We investigate the magnetic field variation of the thermally activated flux flow resistivity, ρ TAFF and flux flow critical current density, J c, in a weakly pinned thin film of the amorphous superconductor a-MoGe, where vortices are in a fluid state over a large range of magnetic fields. We show that both quantities can be understood within the framework of collective pinning theory. In particular, our results demonstrate that a 'peak effect' can arise at the order-disorder transition of the vortex lattice even when both the ordered and disordered states are vortex fluids, such as the boundary between a hexatic vortex fluid and an isotropic vortex liquid.

This paper represents a converged exposition of machine learning approach on various network security applications specifying the possible future scope and detailed outcome of the researches on the basis of intrusion detection, analysis of malware behavior, internet traffic classification, and other security aspects. The complexity of the respective algorithms and the challenges of using them for network security applications are also discussed which would help in understanding the current scenario and the future prospects.

The hexatic fluid refers to a phase in between a solid and a liquid that has short-range positional order but quasi-long-range orientational order. In the celebrated theory of Berezinskii, Kosterlitz, and Thouless and subsequently refined by Halperin, Nelson, and Young, it was predicted that a two-dimensional hexagonal solid can melt in two steps: first, through a transformation from a solid to a hexatic fluid, which retains quasi-long-range orientational order; and then from a hexatic fluid to an isotropic liquid. In this Letter, using a combination of real space imaging and transport measurements, we show that the two-dimensional vortex lattice in an a-MoGe thin film follows this sequence of melting as the magnetic field is increased. Identifying the signatures of various transitions on the bulk transport properties of the superconductor, we construct a vortex phase diagram for a two-dimensional superconductor.

Static video summarization techniques aim to represent the salient content in a video by extracting a set of keyframes for presentation to the user. An efficient key-frame extraction process is thus vital for effective video summarization, browsing and indexing in content-based video retrieval systems. In this paper, a three phased approach for key-frame extraction is proposed which aims to represent a static summary of a video. The first phase deals with detecting the best representative frame(s) for each shot in the video. The second and third phases comprise of techniques for intra-shot and inter-shot redundancy reduction using SURF and GIST on the extracted key-frames in the first phase. At the end of each phase, comparison between the system generated summary and user summary is performed. A comparative analysis between SURF and GIST for redundancy reduction is also presented. Experimental evaluation of the results on a test set of videos from sports, movie songs, music albums and documentaries show that the proposed method achieves high precision and recall values in all the cases. Keywords—Static video summarization; redundancy reduction; SURF; GIST; dynamic thresholding

Multilocational field trials were conducted in grapevines at four different locations by applying hydrogen cyanamide 50% SL during 2006-2007. In order to determine the residue of hydrogen cyanamide in grape, hydrogen cyanamide 50% SL was applied to the freshly pruned grapevines at the rate of 1.20% a.i./L, 2.40% a.i./L, 4.80% a.i./L along with untreated control. No residue was detected in grape berries at the time of harvest irrespective of any locations.

The increasing trend in use of computer systems in safety critical applications has driven the researchers to develop techniques to achieve high degree of fault tolerance. In mission critical applications like banking, satellite launching etc. a single failure may incur huge monitory loss. So far numerous techniques have been developed to impart fault tolerance in computer systems. Dual redundant systems are widely used in applications where fault tolerance is required. Although there are commercially available dual redundant fault tolerant systems, high cost and lack of customizability of those systems render them unusable in some cases. In this paper we present an implementation of a dual redundant system using low cost off-the-shelf personal computers.