9,735 research outputs found
Comparison of Hadronic Interaction Models at Auger Energies
The three hadronic interaction models DPMJET 2.55, QGSJET 01, and SIBYLL 2.1,
implemented in the air shower simulation program CORSIKA, are compared in the
energy range of interest for the Pierre Auger experiment. The model dependence
of relevant quantities in individual hadronic interactions and air showers is
investigated.Comment: Contribution to XII Int. Symp. on Very High Energy Cosmic Ray
Interactions, 4 pages, 8 figure
Formulation of additional observables for ENTREE
The S-band X and Y angles, SAMS, and TACAN range and bearing were incorporated into the ENTREE software for use by experimenters at LaRC for entry trajectory reconstruction purposes. Background discussions present the need for this added capability. Formulations for the various observables are presented. Both north-south and east-west antenna mounts were provided for in the S-band angle computations. Sub-vehicle terrain height variations are included in the SAMS model. Local magnetic variations were incorporated for the TACAN bearing computations. Observable formulations are discussed in detail along with the partial computations
Thermal conductance as a probe of the non-local order parameter for a topological superconductor with gauge fluctuations
We investigate the effect of quantum phase slips on a helical quantum wire
coupled to a superconductor by proximity. The effective low-energy description
of the wire is that of a Majorana chain minimally coupled to a dynamical
gauge field. Hence the wire emulates a matter-coupled gauge
theory, with fermion parity playing the role of the gauged global symmetry.
Quantum phase slips lift the ground state degeneracy associated with unpaired
Majorana edge modes at the ends of the chain, a change that can be understood
as a transition between the confined and the Higgs-mechanism regimes of the
gauge theory. We identify the quantization of thermal conductance at the
transition as a robust experimental feature separating the two regimes. We
explain this result by establishing a relation between thermal conductance and
the Fredenhagen-Marcu string order-parameter for confinement in gauge theories.
Our work indicates that thermal transport could serve as a measure of non-local
order parameters for emergent or simulated topological quantum order.Comment: 5 pages, 2 figures; v2: different introduction, added references,
updated figure 2; published version to appear in PR
Minimal circuit for a flux-controlled Majorana qubit in a quantum spin-Hall insulator
We construct a minimal circuit, based on the top-transmon design, to rotate a
qubit formed out of four Majorana zero-modes at the edge of a two-dimensional
topological insulator. Unlike braiding operations, generic rotations have no
topological protection, but they do allow for a full characterization of the
coherence times of the Majorana qubit. The rotation is controlled by variation
of the flux through a pair of split Josephson junctions in a Cooper pair box,
without any need to adjust gate voltages. The Rabi oscillations of the Majorana
qubit can be monitored via oscillations in the resonance frequency of the
microwave cavity that encloses the Cooper pair box.Comment: Contribution for the proceedings of the Nobel Symposium on
topological insulators. 8 pages, 6 figure
Web Auctions in Europe
This paper argues that a better understanding of the business model of web auctions can be reached if we adopt a broader view and provide empirical research from different sites. In this paper the business model of web auctions is refined into four dimensions. These are auction model, motives, exchange processes, and stakeholders. One of the objects of this research is to redefine the blurry concept of the business model by analyzing one business model, the web auction model. We show in this research the complexity and diversity of factors contributing to the success of the web auction model. By generalizing the results to the level of business model we also show how complex and diverse business models can be. Motivated by the lack of empirically grounded justification for the mixed business results of web auctions, this paper adopts a qualitative approach that includes telephone interviews with web auctions developed in different European countries.exchange processes;stakeholders;Web auctions
Monte Carlo simulations of air showers in atmospheric electric fields
The development of cosmic ray air showers can be influenced by atmospheric
electric fields. Under fair weather conditions these fields are small, but the
strong fields inside thunderstorms can have a significant effect on the
electromagnetic component of a shower. Understanding this effect is
particularly important for radio detection of air showers, since the radio
emission is produced by the shower electrons and positrons. We perform Monte
Carlo simulations to calculate the effects of different electric field
configurations on the shower development. We find that the electric field
becomes important for values of the order of 1 kV/cm. Not only can the energy
distribution of electrons and positrons change significantly for such field
strengths, it is also possible that runaway electron breakdown occurs at high
altitudes, which is an important effect in lightning initiation.Comment: 24 pages, 19 figures, accepted for publication in Astroparticle
Physic
Out-of-plane focusing grating couplers for silicon photonics integration with optical MRAM technology
We present the design methodology and experimental characterization of compact out-of-plane focusing grating couplers for integration with magnetoresistive random access memory technology. Focusing grating couplers have recently found attention as layer-couplers for photonic-electronic integration. The components we demonstrate are designed for a wavelength of 1550 nm, fabricated in a standard 220 nm SOI photonic platform and optimized given the fabrication restrictions for standard 193-nm UV lithography. For the first time, we extend the design based on the phase matching condition to a two-dimensional (2-D) grating design with two optical input ports. We further present the experimental characterization of the focusing behaviour by spatially probing the emitted beam with a tapered-and-lensed fiber and demonstrate the polarization controlling capabilities of the 2-D FGCs
Gay-Straight Alliances as Settings to Discuss Health Topics: Individual and Group Factors Associated with Substance Use, Mental Health, and Sexual Health Discussions
Sexual minority (e.g. lesbian, gay, bisexual, questioning; LGBQ) and gender minority (e.g. transgender) youth experience myriad health risks. Gay-Straight Alliances (GSAs) are school-based settings where they may have opportunities to discuss substance use, mental health, and sexual health issues in ways that are safe and tailored to their experiences. Attention to these topics in GSAs could aid in developing programming for these settings. Among 295 youth from 33 Massachusetts high-school GSAs (69% LGBQ, 68% cisgender female, 68% White, Mage = 16.06), we examined how often youth discussed these topics within their GSA and identified factors associated with having more of these discussions. Youth and GSAs as a whole varied in their frequency of discussing these topics. Youth who accessed more information/resources in the GSA and did more advocacy more frequently engaged in discussions around substance use, mental health and sexual health. Youth who reported greater victimization more often discussed substance use and mental health, but not sexual health. Finally, GSAs whose members collectively reported greater victimization more frequently discussed these topics. These findings can assist the development of health programming to be delivered within GSAs
Depositional environments and diagenesis of the Mississippian Bottineau interval (Lodgepole) in North Dakota
Bottineau interval rocks from the North Dakota part of the Williston Basin comprise a single marine transgression/regression cycle, Early Mississippian (lower Scallion subinterval) marine transgression from the restricted depositional environment of the Bakken Formation resulted in normal marine circulation, Six major facies were developed: (1) the central basin, (2) basin flank, (3) open shelf, (4) crinoidal mudstone, (5) gray shale, and (6) restricted shelf. Marine transgression continued until upper Scallion subinter val time, by which time the open shelf facies had already prograded over the gray shale and crinoidal mudstone facies.
Marine regression had begun by middle Bottineau interval (Virden subinterval) deposition. Three younger shallow water facies were developed along the margin of the basin: (1) the pelletal grain stone, (2) oolite grainstone, and (3) lagoonal. These facies pro graded basinward over deeper water facies as marine regression con tinued until, by Flossie Lake subinterval time, these shallow water facies were being deposited in the central basin area. Bottineau interval sedimentation terminated with continued marine regression and a transition to deposition of shallower water Tilston interval sediments.
Two diagenetic provinces, basin and shelf, with different dia genetic histories, were identified in Bottineau interval rocks. Dia genetic processes were post- or pre-lithification events. Prelithification processes included biologic acthity, compaction, soft sediment deformation, pyrite replacement, cementation, and neomorphism. Biologic activity occurred early, both during and after deposition, Pyrite replacement, soft sediment deformation, precipitation of fringing cement, and microstylolitization occurred shortly after deposition. Later precipitation of equant and overgrowth cements prevented further microstylolitization in cement-lithified fabrics. All pre-lithification processes ceasec once cementation and neomorphism had completely lithified the sediments.
Post-lithification processes included stylolitization, solution, fracturing, silicification, hematite replacement, dolomitization, and anhydritization. Stylolitization and fracturing began after complete lithification, as did silicification which produced chert nodules in the restricted shelf facies. This was followed by hematite replacement of matrix and allochems. Solution voids formed prior to, or during dolomitization as meteoric waters dissolved skeletal allochems. Anhydritization was the last event observed to have altered Bottineau interval rocks.
Areas of potential petroleum production exist from the L2 interval in northwestern North Dakota, from structural traps resulting from salt solution of the Prairie Formation in north-central North Dakota, and from structural and stratigraphic traps along the erosional unconformity in eastern North Dakota
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