Using mobile RE tools to give end-users their own voice

Researchers highlight end-user involvement in system design as an important concept for developing useful and usable solutions. However, end-user involvement in software engineering is still an open-ended topic. Novel paradigms such as service-oriented computing strengthen the need for more active end-user involvement in order to provide systems that are tailored to individual end-user needs. Our work is based on the fact that the majority of end-users are familiar with mobile devices and use an increasing number of mobile applications. A mobile tool enabling end-user led requirements elicitation could be just one of many applications installed on end-users' mobile devices. In this paper, we present a framework of end-user involvement in requirements elicitation which motivates our research. The main contribution of our research is a tool-supported requirements elicitation approach allowing end-users to document needs in situ. Furthermore, we present first evaluation results to highlight the feasibility of on-site end-user led requirements elicitation

Reply to [arXiv:1201.5347] "Comment on 'Vortex-assisted photon counts and their magnetic field dependence in single-photon superconducting detectors'"

We argue that cutoff in the London model cannot be settled without use of the microscopic theory

Corticosterone-Induced Potentiation of Cocaine Seeking: A Potential Role for Organic Cation Transporter 3

While it is known that stress plays a role in the relapse of cocaine-seeking behavior, recent studies demonstrate that stress may be acting as a stage setter rather than directly triggering further cocaine use. This model suggests stimuli that do not normally evoke relapse under stress-free conditions may result in drug seeking when the exposure occurs under stressful conditions. In this study, we examined the corticosterone-dependent potentiation of cocaine-induced reinstatement by a stressor, electric footshock (EFS), in rats following cocaine self-administration and extinction. We found that in rats with a history of drug exposure under low intake conditions, footshock alone did not reinstate cocaine seeking, but did result in a potentiation of reinstatement in response to a subthreshold dose of cocaine (2.5 mg/kg, ip.). This effect was abolished in adrenalectomized rats and reproduced in intact animals receiving a physiologically relevant dose of corticosterone (2.0 mg/kg, ip.). Administration of the glucocorticoid receptor (GR) antagonist RU-486 did not block these effects, suggesting a rapid, non-GR mediated mechanism. In order to determine the site of action, we performed in vivo microdialysis to measure dopamine levels in the nucleus accumbens (NAc) and found that, similar to its actions on cocaine-seeking behavior, corticosterone potentiated cocaine-induced increases in dopamine. In support of this evidence, direct administration of corticosterone into the NAc or prefrontal cortex (PFC) potentiated reinstatement to a subthreshold dose of cocaine, an effect that was blocked with pretreatment of the dopamine antagonist, fluphenazine. Through immunoflourescence studies, we have shown the presence of a high capacity, corticosterone sensitive, monoamine transporter, organic cation transporter 3 (OCT3), located in the NAc adjacent to tyrosine hydroxylase terminals, suggesting a potential interaction with dopamine clearance. Based on this, we hypothesize the mechanism involves corticosterone inhibition of OCT3-mediated dopamine clearance. In support of this mechanism, pretreatment of rats with normetanephrine, a non-glucocorticoid OCT3 inhibitor mimics the effect of corticosterone on reinstatement. These results suggest a novel mechanism through which stress may modulate dopaminergic signaling and promote drug-seeking behavior

Tunneling conductance in normal metal - triplet superconductor junction

We calculate the tunneling conductance spectra of a normal metal / insulator / triplet superconductor from the reflection amplitudes using the Blonder-Tinkham-Klapwijk (BTK) formula. For the triplet superconductor we assume one special p-wave order parameter having line nodes and two two dimensional $f$-wave order parameters with line nodes breaking the time-reversal symmetry. Also we examine nodeless pairing potentials. The tunneling peaks are due to the formation of bound states for each surface orientation at discrete quasiparticles trajectory angles. The tunneling spectra can be used to distinguish the possible candidate pairing states of the superconductor Sr$_2$RuO$_4$.Comment: 4 pages with 3 figures, presented at the second Euroconference on Vortex Matter in Superconductors, 15-25 September 2001, Crete, Greec

Intrinsic Josephson Effect and Violation of the Josephson Relation in Layered Superconductors

Equations describing the resistive state of a layered superconductor with anisotropic pairing are derived. The similarity with a stack of Josephson junctions is found at small voltages only, when current density in the direction perpendicular to the layers can be interpreted as a sum of the Josephson superconducting, the Ohmic dissipative and the interference currents. In the spatially uniform state differential conductivity at higher voltages becomes negative. Nonuniformity of the current distribution generates the branch imbalance and violates the Josephson relation between frequency and voltage.Comment: 11 pages, no figures, revtex, to be published in Phys. Rev. Let

Linear response and collective oscillations in superconductors with d-wave pairing

Simple and physically transparent equations for the linear response of layered superconductors with d-wave symmetry of the order parameter are derived by means of the quasiclassic kinetic theory of superconductivity. Responses to solenoidal and potential electric fields have different frequency dependencies. The conductivity describing the response to the solenoidal field is limited by the momentum relaxation, like in a normal metal. The response to the potential electric field depends, in addition, on the branch imbalance relaxation rate. The damping of plasma oscillations of superconducting electrons is determined by dielectric relaxation and is small. Relaxation of branch imbalance determined by elastic scattering is large enough to make the Carlson-Goldman mode in d-wave superconductors overdamped.Comment: 11 pages, latex, no figures, submitted to Physical Review

Thermally Assisted Penetration and Exclusion of Single Vortex in Mesoscopic Superconductors

A single vortex overcoming the surface barrier in a mesoscopic superconductor with lateral dimensions of several coherence lengths and thickness of several nanometers provides an ideal platform to study thermal activation of a single vortex. In the presence of thermal fluctuations, there is non-zero probability for vortex penetration into or exclusion from the superconductor even when the surface barrier does not vanish. We consider the thermal activation of a single vortex in a mesoscopic superconducting disk of circular shape. To obtain statistics for the penetration and exclusion magnetic fields, slow and periodic magnetic fields are applied to the superconductor. We calculate the distribution of the penetration and exclusion fields from the thermal activation rate. This distribution can also be measured experimentally, which allows for a quantitative comparison.Comment: 7 pages, 4 figure

Charge current in ferromagnet - triplet superconductor junctions

We calculate the tunneling conductance spectra of a ferromagnetic metal / insulator / triplet superconductor from the reflection amplitudes using the Blonder-Tinkham-Klapwijk (BTK) formula. For the triplet superconductor, we assume one special $p$-wave order parameter, having line nodes, and two two dimensional $f$-wave order parameters with line nodes, breaking the time reversal symmetry. Also we examine nodeless pairing potentials. The evolution of the spectra with the exchange potential depends solely on the topology of the gap. The weak Andreev reflection within the ferromagnet results in the suppression of the tunneling conductance and eliminates the resonances due to the anisotropy of the pairing potential. The tunneling spectra splits asymmetrically with respect to $E=0$ under the influence of an external magnetic field. The results can be used to distinguish between the possible candidate pairing states of the superconductor Sr$_2$RuO$_4$.Comment: 15 pages with 8 figure

Emergence of intrinsic superconductivity below 1.178 K in the topologically non-trivial semimetal state of CaSn3

Topological materials which are also superconducting are of great current interest, since they may exhibit a non-trivial topologically-mediated superconducting phase. Although there have been many reports of pressure-tuned or chemical-doping-induced superconductivity in a variety of topological materials, there have been few examples of intrinsic, ambient pressure superconductivity in a topological system having a stoichiometric composition. Here, we report that the pure intermetallic CaSn3 not only exhibits topological fermion properties but also has a superconducting phase at 1.178 K under ambient pressure. The topological fermion properties, including the nearly zero quasi-particle mass and the non-trivial Berry phase accumulated in cyclotron motions, were revealed from the de Haas-van Alphen (dHvA) quantum oscillation studies of this material. Although CaSn3 was previously reported to be superconducting at 4.2K, our studies show that the superconductivity at 4.2K is extrinsic and caused by Sn on the degraded surface, whereas its intrinsic bulk superconducting transition occurs at 1.178 K. These findings make CaSn3 a promising candidate for exploring new exotic states arising from the interplay between non-trivial band topology and superconductivity, e.g. topological superconductivityComment: 20 pages,4 figure