Critical current of a superconductor measured via injection of spin polarized carriers

In this paper we report a direct evidence of the suppression of critical current due to pair-breaking in a superconducting micro-bridge when the measurement is carried out by injecting spin polarised carriers instead of normal electrons. A thin layer of La0.7Ca0.3MnO3 was used as the source of spin polarised carriers. The micro-bridge was formed on the DyBa2Cu3O7-d thin film by photo-lithographic techniques. The design of our spin-injection device allowed us to inject spin-polarised carriers from the La0.7Ca0.3MnO3 layer directly to the DyBa2Cu3O7- d micro-bridge (without any insulating buffer layer) making it possible to measure the critical current when polarised electrons alone are injected into the superconductor. Our results confirm the role of polarised carriers in breaking the Cooper pairs in the superconductor.Comment: 8 pages, 4 figure

Determination of the Elastic Constants of Composites Through the Inversion of Leaky Lamb Wave Data

Analysis and prediction of the response of composite laminates to external loads are essential for the design of composite structures. This in turn requires a precise knowledge of their mechanical properties including their constitutive behavior. It is reasonable to assume that, in the bulk, the overall behavior of unidirectional graphite/epoxy composites is the same as that of a homogeneous, transversely isotropic material with its symmetry axis along the fiber direction. Then the linear elastic response of the material can be described by means of five elastic constants. If the values of these constants can be determined, then the stress analysis of a laminate with a given number and stacking order of the laminae can, in principle, be carried out. However, the measurement of the elastic constants by conventional, destructive techniques is difficult and often, inaccurate. Thus, the availability of alternative, preferably nondestructive methods, for the determination of the elastic costants of the material would be extremely helpfu

Separating Developmental and Environmental Effects on Fluctuating Asymmetry in Lythrum salicaria and Penthorum sedoides

Environmental stress can disrupt developmental processes on biological, physiological, and chemical levels and thereby affect the symmetry of a trait. For this reason, fluctuating asymmetry is often proposed as a measure of stress encountered by an individual. One problem is that asymmetry may have multiple causes, including developmental noise and genetic background, and genetic differences may interact with any physiological stress imposed by the environment. The main objective of this research was to determine whether developmental noise and genetic stress can be separated from environmental effects on leaf asymmetry. The experiments were conducted on two wetland plants, Lythrum salicaria (purple loosestrife) and Penthorum sedoides (ditch stonecrop). Replicates of different genotypes were measured when young and after they matured, with the latter group grown under two nutrient treatments. The largest and healthiest leaf of each plant was measured for length, width, and differences in width between the left and right sides (measuring from the central vein at the widest point). Nutrient enrichment increased leaf asymmetry, while age reduced asymmetry in L. salicaria. However, leaf asymmetry changed only as a consequence of development in P. sedoides and decreased. Genotype did not affect asymmetry in either species

Remote state preparation by multiple observers using a single copy of a two-qubit entangled state

We consider a scenario of remote state preparation (RSP) of qubits in the context of sequential network scenario. A single copy of an entangled state is shared between Alice on one side, and several Bobs on the other, who sequentially perform unsharp single-particle measurements in order to prepare a specific state. In the given scenario without any shared randomness between the various Bobs, we first determine the classical bound of fidelity for the preparation of remote states by the Bobs. We then show that there can be at most 6 number of Bobs who can sequentially and independently prepare the remote qubit state in Alice's lab with fidelity exceeding the classical bound in the presence of shared quantum correlations. The upper bound is achieved when the singlet state is initially shared between Alice and the first Bob and every Bob prepares a state chosen from the equatorial circle of the Bloch sphere. Then we introduce a new RSP protocol for non-equatorial ensemble of states. The maximum number of Bobs starts to decrease from six when either the choice of remote states is shifted from the equatorial circle towards the poles of the Bloch sphere, or when the initial state shifts towards non-maximally entangled pure and mixed states.Comment: 41 pages, 9 figures, 6 table

Aquatic Macrophyte Diversity and Habitat Characterization of the Cuyahoga River Watershed in Northeastern Ohio

Author Institution: Dept. of Biological, Geological and Environmental Sciences, Cleveland State University, OHWe surveyed aquatic macrophyte diversity and abundance at 20 sites along the main channel of the Cuyahoga River and its tributaries. These sites included 12 sites in the watershed at which an Index of Biological Integrity (IBI) for fish communities deviated significantly from a value predicted by a statistical model of landscape urbanization and stream habitat quality. These sites were classified as Best of the Best, Worst of the Best, Best of the Worst and Worst of the Worst among 164 sites within the Cuyahoga basin. In order to characterize a site, we collected data on the physical features of the stream and quantified the species abundance of aquatic macrophytes in a 100 m transect. Within each transect, measurements of stream width, bankfull width, stream depth, bankfull depth, and canopy cover were recorded every 10 m. Nitrate, phosphate, and ammonia content of water samples were also assayed. The quality of stream habitat for each site was quantified using the Qualitative Habitat Evaluation Index (QHEI). Strong significant correlations between the measure of stream depth and stream width as well as canopy coverage and bankfull width were observed. A weak significant correlation was found between IBI and QHEI scores. Additional analysis showed that water chemistry did not influence QHEI or IBI scores. An analysis of variance indicated that the IBI scores significantly differed among site types. Macrophytes were discovered at seven of the 20 sites with an overall richness of 11 species among all sites. The most common aquatic macrophytes were: Elodea canadensis L., Sparganium americanum Nutt., and Sagittaria latifolia Willd. Results demonstrate that physical stream characteristics are strong indicators of fish population integrity, but are not necessarily indicative of aquatic macrophyte assemblages. Storms severely impacted many streams during the survey, possibly altering macrophyte assemblages. Further surveys should be undertaken at additional sites within the Cuyahoga River watershed for a comprehensive assessment of aquatic macrophytes

Sectorwise assessment of glacial lake outburst flood danger in the Indian Himalayan region

Climate change and associated glacier recession have led to the formation of new glacial lakes and the expansion of existing ones across the Himalayas. Many pose a potential glacial lake outburst flood (GLOF) threat to downstream communities and infrastructure. In this paper, 4418 glacial lakes in the Indian Himalayan Region and 636 transboundary lakes are analyzed. We consider hazard, exposure, and integrated danger levels using robust geographic information system-based automated approaches. The hazard level of lakes was estimated based on the potential for avalanches to strike the lake, size of the lake and its upstream watershed, and distal slope of its dam. Exposure levels were calculated by intersecting cropland, roads, hydropower projects, and the human population with potential GLOF trajectories. Then, GLOF danger was determined as a function of hazard and exposure. The study demonstrates that Jammu and Kashmir (JK) is potentially the most threatened region in terms of total number of very high and high danger lakes (n = 556), followed by Arunachal Pradesh (AP) (n = 388) and Sikkim (SK) (n = 219). Sectorwise, JK faces the greatest GLOF threat to roads and population, whereas the threat to cropland and hydropower is greatest in AP and SK, respectively. Transboundary lakes primarily threaten AP and, to a lesser extent, Himachal Pradesh (HP). For Uttarakhand (UK), the impacts of potential future glacial lakes, expected to form during rapid ongoing glacier recession because of climate change, are explored. Finally, a comparison of current results with previous studies suggests that 13 lakes in SK, 5 in HP, 4 in JK, 2 in UK, and 1 in AP are of highest priority for local investigation and potential risk reduction measures. Current results are of vital importance to policymakers, disaster management authorities, and the scientific community

Effect of High Temperature on Reproductive Phase of Plants: A Review

Climate change is a universal challenge that threatens the very existence of life on planet Earth. One of the most sensitive areas to climate change is agriculture. Climate change affects precipitation, cyclones, clouds, temperature, humidity, and CO2 levels. All these factors affect plant productivity which poses another grave concern in feeding the ever-increasing population. The productivity in terms of crop yield is reduced due to a direct correlation between phenology and climate change. The reproductive organs of a plant and other parameters that define good fertility of a species are all affected by the increasing temperatures during their vegetative and reproductive phases of growth and development. Thus, this review is an attempt to understand the effect of climate change on the reproductive structures of plants and discuss the short-term and long-term adaptations in plants and agriculture as mitigation measures to combat the significant yield loss in developing countries

Electronic structure, phase stability and chemical bonding in Th2_2Al and Th2_2AlH4_4

We present the results of theoretical investigation on the electronic structure, bonding nature and ground state properties of Th$_2$Al and Th$_2$AlH$_4$ using generalized-gradient-corrected first-principles full-potential density-functional calculations. Th$_2$AlH$_4$ has been reported to violate the "2 \AA rule" of H-H separation in hydrides. From our total energy as well as force-minimization calculations, we found a shortest H-H separation of 1.95 {\AA} in accordance with recent high resolution powder neutron diffraction experiments. When the Th$_2$Al matrix is hydrogenated, the volume expansion is highly anisotropic, which is quite opposite to other hydrides having the same crystal structure. The bonding nature of these materials are analyzed from the density of states, crystal-orbital Hamiltonian population and valence-charge-density analyses. Our calculation predicts different nature of bonding for the H atoms along $a$ and $c$. The strongest bonding in Th$_2$AlH$_4$ is between Th and H along $c$ which form dumb-bell shaped H-Th-H subunits. Due to this strong covalent interaction there is very small amount of electrons present between H atoms along $c$ which makes repulsive interaction between the H atoms smaller and this is the precise reason why the 2 {\AA} rule is violated. The large difference in the interatomic distances between the interstitial region where one can accommodate H in the $ac$ and $ab$ planes along with the strong covalent interaction between Th and H are the main reasons for highly anisotropic volume expansion on hydrogenation of Th$_2$Al.Comment: 14 pages, 9 figure

Performance of a Large-Area GEM Detector Prototype for the Upgrade of the CMS Muon Endcap System

Gas Electron Multiplier (GEM) technology is being considered for the forward muon upgrade of the CMS experiment in Phase 2 of the CERN LHC. Its first implementation is planned for the GE1/1 system in the $1.5 < \mid\eta\mid < 2.2$ region of the muon endcap mainly to control muon level-1 trigger rates after the second long LHC shutdown. A GE1/1 triple-GEM detector is read out by 3,072 radial strips with 455 $\mu$rad pitch arranged in eight $\eta$-sectors. We assembled a full-size GE1/1 prototype of 1m length at Florida Tech and tested it in 20-120 GeV hadron beams at Fermilab using Ar/CO$_{2}$ 70:30 and the RD51 scalable readout system. Four small GEM detectors with 2-D readout and an average measured azimuthal resolution of 36 $\mu$rad provided precise reference tracks. Construction of this largest GEM detector built to-date is described. Strip cluster parameters, detection efficiency, and spatial resolution are studied with position and high voltage scans. The plateau detection efficiency is [97.1 $\pm$ 0.2 (stat)]\%. The azimuthal resolution is found to be [123.5 $\pm$ 1.6 (stat)] $\mu$rad when operating in the center of the efficiency plateau and using full pulse height information. The resolution can be slightly improved by $\sim$ 10 $\mu$rad when correcting for the bias due to discrete readout strips. The CMS upgrade design calls for readout electronics with binary hit output. When strip clusters are formed correspondingly without charge-weighting and with fixed hit thresholds, a position resolution of [136.8 $\pm$ 2.5 stat] $\mu$rad is measured, consistent with the expected resolution of strip-pitch/$\sqrt{12}$ = 131.3 $\mu$rad. Other $\eta$-sectors of the detector show similar response and performance.Comment: 8 pages, 32 figures, submitted to Proc. 2014 IEEE Nucl. Sci. Symposium, Seattle, WA, reference adde