2,177 research outputs found
Superconductivity of Quasi-One-Dimensional Electrons in Strong Magnetic Field
The superconductivity of quasi-one-dimensional electrons in the magnetic
field is studied. The system is described as the one-dimensional electrons with
no frustration due to the magnetic field. The interaction is assumed to be
attractive between electrons in the nearest chains, which corresponds to the
lines of nodes of the energy gap in the absence of the magnetic field. The
effective interaction depends on the magnetic field and the transverse
momentum. As the magnetic field becomes strong, the transition temperature of
the spin-triplet superconductivity oscillates, while that of the spin-singlet
increases monotonically.Comment: 15 pages, RevTeX, 3 PostScript figures in uuencoded compressed tar
file are appende
Rapid changes in shape and number of MHC class II expressing cells in rat airways after Mycoplasma pulmonis infection
This article is made available for unrestricted research re-use and secondary analysis in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.Mycoplasma pulmonis infection in rodents causes a chronic inflammatory airway disease with a strong immunological component, leading to mucosal remodeling and angiogenesis. We sought to determine the effect of this infection on the shape and number of dendritic cells and other major histocompatibility complex (MHC) class II expressing cells in the airway mucosa of Wistar rats. Changes in the shape of subepithelial OX6 (anti-MHC class II)-immunoreactive cells were evident in the tracheal mucosa 2 days after intranasal inoculation with M. pulmonis. By 1 week, the shape of the cells had changed from stellate to rounded (mean shape index increased from 0.42 to 0.77). The number of OX6-positive cells was increased 6-fold at 1 week and 16-fold at 4 weeks. Coincident with these changes, many columnar epithelial cells developed OX6 immunoreactivity, which was still present at 4 weeks. We conclude that M. pulmonis infection creates a potent immunologic stimulus that augments and transforms the OX6-immunoreactive cell population in the airways by changing the functional state of airway dendritic cells, initiating an influx of MHC class II expressing cells, and activating expression of MHC class II molecules by airway epithelial cells
Quantum Fully Homomorphic Encryption With Verification
Fully-homomorphic encryption (FHE) enables computation on encrypted data
while maintaining secrecy. Recent research has shown that such schemes exist
even for quantum computation. Given the numerous applications of classical FHE
(zero-knowledge proofs, secure two-party computation, obfuscation, etc.) it is
reasonable to hope that quantum FHE (or QFHE) will lead to many new results in
the quantum setting. However, a crucial ingredient in almost all applications
of FHE is circuit verification. Classically, verification is performed by
checking a transcript of the homomorphic computation. Quantumly, this strategy
is impossible due to no-cloning. This leads to an important open question: can
quantum computations be delegated and verified in a non-interactive manner? In
this work, we answer this question in the affirmative, by constructing a scheme
for QFHE with verification (vQFHE). Our scheme provides authenticated
encryption, and enables arbitrary polynomial-time quantum computations without
the need of interaction between client and server. Verification is almost
entirely classical; for computations that start and end with classical states,
it is completely classical. As a first application, we show how to construct
quantum one-time programs from classical one-time programs and vQFHE.Comment: 30 page
Superconductivity of Quasi-One and Quasi-Two Dimensional Tight-Binding Electrons in Magnetic Field
The upper critical field of the tight-binding electrons in the
three-dimensional lattice is investigated.
The electrons make Cooper pairs between the eigenstates with the same energy
in the strong magnetic field. The transition lines in the quasi-one dimensional
case are shown to deviate from the previously obtained results where the
hopping matrix elements along the magnetic field are neglected. In the absence
of the Pauli pair breaking the transition temperature of the quasi-two
dimensional electrons is obtained to oscillationally increase as the magnetic
field becomes large and reaches to in the strong field as in the
quasi-one dimensional case.Comment: 4pages,4figures,to be published in J.Phys.Soc.Jp
Infrared behavior of interacting bosons at zero temperature
We review the infrared behavior of interacting bosons at zero temperature.
After a brief discussion of the Bogoliubov approximation and the breakdown of
perturbation theory due to infrared divergences, we present two approaches that
are free of infrared divergences -- Popov's hydrodynamic theory and the
non-perturbative renormalization group -- and allow us to obtain the exact
infrared behavior of the correlation functions. We also point out the
connection between the infrared behavior in the superfluid phase and the
critical behavior at the superfluid--Mott-insulator transition in the
Bose-Hubbard model.Comment: 8 pages, 4 figures. Proceedings of the 19th International Laser
Physics Workshop, LPHYS'10 (Foz do Iguacu, Brazil, July 5-9, 2010
Effect of nearest- and next-nearest neighbor interactions on the spin-wave velocity of one-dimensional quarter-filled spin-density-wave conductors
We study spin fluctuations in quarter-filled one-dimensional
spin-density-wave systems in presence of short-range Coulomb interactions. By
applying a path integral method, the spin-wave velocity is calculated as a
function of on-site (U), nearest (V) and next-nearest (V_2) neighbor-site
interactions. With increasing V or V_2, the pure spin-density-wave state
evolves into a state with coexisting spin- and charge-density waves. The
spin-wave velocity is reduced when several density waves coexist in the ground
state, and may even vanish at large V. The effect of dimerization along the
chain is also considered.Comment: REVTeX, 11 pages, 9 figure
Failure detection for the Bin-Packing Constraint
Abstract In addition to a filtering algorithm, the Pack constraint introduced by Shaw uses a failure detection algorithm. This test is based on a reduction of the partial solution to a standard bin-packing problem and the computation of a bin-packing lower bound (BPLB) on the reduced problem. A first possible improvement on Shaw's test is to use a stronger BPLB. In particular, Labbé's lower bound was recently proved to dominate Martello's lower bound used by Shaw. A second possible improvement is to use a reduction different from the one introduced by Shaw. We propose two new reduction algorithms and prove that one of them theoretically dominates the others. All the proposed improvements on the failure test are evaluated using the COMET System
Unforgeable Quantum Encryption
We study the problem of encrypting and authenticating quantum data in the
presence of adversaries making adaptive chosen plaintext and chosen ciphertext
queries. Classically, security games use string copying and comparison to
detect adversarial cheating in such scenarios. Quantumly, this approach would
violate no-cloning. We develop new techniques to overcome this problem: we use
entanglement to detect cheating, and rely on recent results for characterizing
quantum encryption schemes. We give definitions for (i.) ciphertext
unforgeability , (ii.) indistinguishability under adaptive chosen-ciphertext
attack, and (iii.) authenticated encryption. The restriction of each definition
to the classical setting is at least as strong as the corresponding classical
notion: (i) implies INT-CTXT, (ii) implies IND-CCA2, and (iii) implies AE. All
of our new notions also imply QIND-CPA privacy. Combining one-time
authentication and classical pseudorandomness, we construct schemes for each of
these new quantum security notions, and provide several separation examples.
Along the way, we also give a new definition of one-time quantum authentication
which, unlike all previous approaches, authenticates ciphertexts rather than
plaintexts.Comment: 22+2 pages, 1 figure. v3: error in the definition of QIND-CCA2 fixed,
some proofs related to QIND-CCA2 clarifie
Renormalization group approach to Fermi Liquid Theory
We show that the renormalization group (RG) approach to interacting fermions
at one-loop order recovers Fermi liquid theory results when the forward
scattering zero sound (ZS) and exchange (ZS) channels are both taken into
account. The Landau parameters are related to the fixed point value of the
``unphysical'' limit of the forward scattering vertex. We specify the
conditions under which the results obtained at one-loop order hold at all order
in a loop expansion. We also emphasize the similarities between our RG approach
and the diagrammatic derivation of Fermi liquid theory.Comment: 4 pages (RevTex) + 1 postcript file, everything in a uuencoded file,
uses epsf (problem with the figure in the first version
Substance use capital: Social resources enhancing youth substance use.
Social capital is described as a protective factor against youth substance use, but it may also be associated with behaviours that do not enhance health. The present study hypothesized that 'substance use capital', i.e. resources favourable to substance use, is a risk factor for substance use and misuse.
We used baseline data from the ongoing Cohort Study on Substance Use Risk Factors (C-SURF) that included a representative sample of young Swiss men (n=5623). Substance use (alcohol, cannabis, 15 illicit drugs, lifetime use, hazardous use and dependence), substance use capital (parental and peer attitudes towards substance use, parental and peer drug use, perceived norms of substance use) and aspects of social capital (relationships with parents and peers) were assessed. Logistic regressions were used to examine the associations between substance-related resources and social resources, and substance use.
Results showed that substance-related resources were associated with an increased risk of substance use (OR between 1.25 and 4.67), whereas social resources' associations with substance use were commonly protective but weaker than substance-related resources. Thus, a drug-friendly environment facilitated substance use and misuse. Moreover, the results showed that peer environments were more drug-friendly than familial environments.
In conclusion, this study highlighted a concept of 'substance use capital', which may be useful for advancing both theoretical and applied knowledge of substance use. Indeed, substance use is not only associated with a lack of social resources, but also with specific drug-friendly social resources coming from environment and background
- …