404 research outputs found
Nernst Effect as a Signature of Quantum Fluctuations in Quasi-1D Superconductors
We study a model for the transverse thermoelectric response due to quantum
superconducting fluctuations in a two-leg Josephson ladder, subject to a
perpendicular magnetic field B and a transverse temperature gradient. The
off-diagonal Peltier coefficient (\alpha_{xy}) and the Nernst effect are
evaluated as functions of B and the temperature T. The Nernst effect is found
to exhibit a prominent peak close to the superconductor-insulator transition
(SIT), which becomes progressively enhanced at low T. In addition, we derive a
relation to diamagnetic response: \alpha_{xy}= -M/T_0, where M is the
equilibrium magnetization and T_0 a plasma energy in the superconducting legs.Comment: An extended (and hopefully more comprehensible) version of an earlier
postin
Community-based environmental monitoring goes to school: translations, detours and escapes
Community-school partnerships are an established practice within environmental science education, where a focus on how local phenomena articulate with broader environmental issues and concerns brings potential benefits for schools, community organisations and local communities. This paper contributes to our understanding of such educational practices by tracing of the diverse socio-material flows that constitute a community environmental monitoring project, where Australian school students became investigators of and advocates for particular sites in their neighbourhood. The theoretical resources of Actor-Network Theory are drawn upon to describe how the project—as conceptualised by its initiators—was enacted as both human and non-human actors sought to progress their own agendas thus translating the concept-project into multiple project realities. We conclude by identifying implications for sustaining educational innovations of this kind
Oncology patients' experience at the interface between hospital and community care: a mixed method investigation
Trunk Refugia : A Simple, Inexpensive Method for Sampling Tree Trunk Arthropods
Trees host a large share of the global arthropod diversity. Several methodologies have been described to sample arthropods from trees, ranging from active sampling techniques (e.g., visual searching, beating, or shaking the branches) to passive sampling devices. The majority of these collection techniques are destructive, and do not specifically target the tree trunk arthropod fauna. Here, we describe an alternative sampling method called trunk refugia (TR). TR are cylindrical shelters made of corrugated cardboard that can be secured to trees using string, and can remain exposed for varying time periods. These refugia are inexpensive, easy to use, and suitable to monitor a diverse array of insects and arachnids. Moreover, TR are nonlethal sampling tools, and allow collecting live individuals for behavioral studies or for rearing.RESUMEN: Los árboles albergan una gran parte de la diversidad global de artrópodos. Varias metodologÃas han sido descritas para muestrear artrópodos de árboles, desde técnicas activas (e.g., búsqueda visual, red de golpeo) hasta dispositivos de muestreo pasivo. La mayorÃa de estas técnicas son letales, y no están dirigidas especÃficamente a los artrópodos de troncos de árboles. Describimos aquà un método alternativo llamado trampas refugio (TR). Las TR son refugios hechos de cartón corrugado que se colocan en los troncos usando cuerda, y pueden permanecer expuestos por perÃodos variables. Estas trampas son económicas, fáciles de usar, y apropiadas para monitorear una gran variedad de insectos y arácnidos. Además, las TR son no-letales, por lo que permiten la colección de individuos vivos para estudios de comportamiento o crianza.Jacob Blaustein Center for Scientific Cooperation; Israel Nature and Parks Authorities (INPA); Israel's National Nature Assessment Program (HAMAARAG); Israel Ministry of Agriculture (131-1793-14)info:eu-repo/semantics/publishedVersio
Random field Ising systems on a general hierarchical lattice: Rigorous inequalities
Random Ising systems on a general hierarchical lattice with both, random
fields and random bonds, are considered. Rigorous inequalities between
eigenvalues of the Jacobian renormalization matrix at the pure fixed point are
obtained. These inequalities lead to upper bounds on the crossover exponents
.Comment: LaTeX, 13 pages, figs. 1a,1b,2. To be published in PR
A local families index formula for d-bar operators on punctured Riemann surfaces
Using heat kernel methods developed by Vaillant, a local index formula is
obtained for families of d-bar operators on the Teichmuller universal curve of
Riemann surfaces of genus g with n punctures. The formula also holds on the
moduli space M{g,n} in the sense of orbifolds where it can be written in terms
of Mumford-Morita-Miller classes. The degree two part of the formula gives the
curvature of the corresponding determinant line bundle equipped with the
Quillen connection, a result originally obtained by Takhtajan and Zograf.Comment: 47 page
The Role of Vortices in the Mutual Coupling of Superconducting and Normal-Metal Films
I propose a possible explanation to a recently observed ``cross-talk'' effect
in metal-insulator-metal trilayers, indicating a sharp peak near a
superconducting transition in one of the metal films. Coulomb interactions are
excluded as a dominant coupling mechanism, and an alternative is suggested,
based on the local fluctuating electric field induced by mobile vortices in the
superconducting layer. This scenario is compatible with the magnitude of the
peak signal and its shape; most importantly, it addresses the {\it
non-reciprocity} of the effect in exchanging the roles of the films.Comment: 13 pages, RevTe
Light-induced self-synchronizing flow patterns
In this paper, we present the observation of light-induced self-synchronizing flow patterns in a light-fluid system. A light beam induces local flow patterns in a fluid, which oscillate periodically or chaotically in time. The oscillations within different regions of the fluid interact with each other through heat-and surface-tension-induced fluid waves, and they become synchronized. We demonstrate optical control over the state of synchronization and over the temporal correlation between different parts of the flow field. Finally, we provide a model to elucidate these results and we suggest further ideas on light controlling flow and vice versa
Alternating Superconductor--Insulator Transport Characteristics in a Quantum Vortex Chain
Experimental studies of magnetoresistance in thin superconducting strips
subject to a perpendicular magnetic field B exhibit a multitude of transitions,
from superconductor to insulator and vice versa alternately. Motivated by this
observation, we study a theoretical model for the transport properties of a
ladder--like superconducting device close to a superconductor--insulator
transition. In this regime, strong quantum fluctuations dominate the dynamics
of the vortex chain forming along the device. Utilizing a mapping of the vortex
system at low energies to one-dimensional (1D) Fermions at a chemical potential
dictated by B, we find that a quantum phase transition of the Ising type occurs
at critical values of the vortex filling, from a superconducting phase near
integer filling to an insulator near 1/2-filling. The current--voltage (I-V)
characteristics of the weakly disordered device in the presence of a d.c.
current bias I is evaluated, and investigated as a function of B, I, the
temperature T and the disorder strength. In the Ohmic regime (I/e << T), the
resulting magnetoresistance R(B) exhibits oscillations similar to the
experimental observation. More generally, we find that the I-V characteristics
of the system manifests a dramatically distinct behavior in the superconducting
and insulating regimes.Comment: 10 pages, 3 figures. arXiv admin note: substantial text overlap with
arXiv:1010.066
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