4,643 research outputs found
Characterization of the T cell receptor repertoire causing collagen arthritis in mice
Collagen type II-induced arthritis (CIA) is generated in susceptible rodent strains by intradermal injections of homologous or heterologous native type II collagen in complete Freund's adjuvant. Symptoms of CIA are analogous to those of the human autoimmune disease, rheumatoid arthritis. CIA is a model system for T cell-mediated autoimmune disease. To study the T cell receptor (TCR) repertoire of bovine type II-specific T cells that may be involved in the pathogenesis of CIA in DBA/1Lac.J (H-2q) mice, 13 clonally distinct T cell hybridomas specific for bovine type II collagen have been established and the alpha and beta chains of their TCRs have been analyzed. These T cell hybridomas recognize epitopes that are shared by type II collagens from distinct species and not by type I collagens, and exhibit a highly restricted TCR-alpha/beta repertoire. The alpha chains of the TCRs employ three V alpha gene subfamilies (V alpha 11, V alpha 8, and V alpha 22) and four J alpha gene segments (J alpha 42, J alpha 24, J alpha 37, and J alpha 32). The V alpha 22 is a newly identified subfamily consisting of approximately four to six members, and exhibits a high degree of polymorphism among four mouse strains of distinct V alpha haplotypes. In addition, the beta chains of the TCRs employ three V beta gene subfamilies (V beta 8, V beta 1, and V beta 6), however the V beta 8.2 gene segment is preferentially utilized (58.3%). In contrast, the J beta gene segment usage is more heterogeneous. On the basis of the highly limited TCR-alpha/beta repertoire of the TCRs of the panel of bovine type II-specific T cell hybrid clones, a significant reduction (60%) of the incidence of arthritis in DBA/1Lac.J mice is accomplished by the use of anti-V beta 8.2 antibody therapy
Relation between stress heterogeneity and aftershock rate in the rate-and-state model
We estimate the rate of aftershocks triggered by a heterogeneous stress
change, using the rate-and-state model of Dieterich [1994].We show that an
exponential stress distribution Pt(au) ~exp(-tautau_0) gives an Omori law decay
of aftershocks with time ~1/t^p, with an exponent p=1-A sigma_n/tau_0, where A
is a parameter of the rate-and-state friction law, and \sigma_n the normal
stress. Omori exponent p thus decreases if the stress "heterogeneity" tau_0
decreases. We also invert the stress distribution P(tau) from the seismicity
rate R(t), assuming that the stress does not change with time. We apply this
method to a synthetic stress map, using the (modified) scale invariant "k^2"
slip model [Herrero and Bernard, 1994]. We generate synthetic aftershock
catalogs from this stress change.The seismicity rate on the rupture area shows
a huge increase at short times, even if the stress decreases on average.
Aftershocks are clustered in the regions of low slip, but the spatial
distribution is more diffuse than for a simple slip dislocation. Because the
stress field is very heterogeneous, there are many patches of positive stress
changes everywhere on the fault.This stochastic slip model gives a Gaussian
stress distribution, but nevertheless produces an aftershock rate which is very
close to Omori's law, with an effective p<=1, which increases slowly with time.
We obtain a good estimation of the stress distribution for realistic catalogs,
when we constrain the shape of the distribution. However, there are probably
other factors which also affect the temporal decay of aftershocks with time. In
particular, heterogeneity of A\sigma_n can also modify the parameters p and c
of Omori's law. Finally, we show that stress shadows are very difficult to
observe in a heterogeneous stress context.Comment: In press in JG
Anomalies, absence of local equilibrium and universality in 1-d particles systems
One dimensional systems are under intense investigation, both from
theoretical and experimental points of view, since they have rather peculiar
characteristics which are of both conceptual and technological interest. We
analyze the dependence of the behaviour of one dimensional, time reversal
invariant, nonequilibrium systems on the parameters defining their microscopic
dynamics. In particular, we consider chains of identical oscillators
interacting via hard core elastic collisions and harmonic potentials, driven by
boundary Nos\'e-Hoover thermostats. Their behaviour mirrors qualitatively that
of stochastically driven systems, showing that anomalous properties are typical
of physics in one dimension. Chaos, by itslef, does not lead to standard
behaviour, since it does not guarantee local thermodynamic equilibrium. A
linear relation is found between density fluctuations and temperature profiles.
This link and the temporal asymmetry of fluctuations of the main observables
are robust against modifications of thermostat parameters and against
perturbations of the dynamics.Comment: 26 pages, 16 figures, revised text, two appendices adde
Dynamics of Energy Transport in a Toda Ring
We present results on the relationships between persistent currents and the
known conservation laws in the classical Toda ring. We also show that
perturbing the integrability leads to a decay of the currents at long times,
with a time scale that is determined by the perturbing parameter. We summarize
several known results concerning the Toda ring in 1-dimension, and present new
results relating to the frequency, average kinetic and potential energy, and
mean square displacement in the cnoidal waves, as functions of the wave vector
and a parameter that determines the non linearity.Comment: 34 pages, 11 figures. Small changes made in response to referee's
comment
The effectiveness Village-Owned Enterprises (BUMDes) Sehati in Nekmese Village Amarasi Sub-District, South Kupang Regency
Purpose: The purpose of this study is to measure and analyze the effectiveness of Sehati Village-Owned Enterprises (BUMDes) in Nekmese Village, South Amarasi District, Kupang Regency.
Research Methodology: This study used descriptive research with a qualitative approach that used the effectiveness measurement criteria of Chambell J.P (1989).
Results: The findings in this study are that BUMDes has been effective with several successes, namely program success, target success, satisfaction with the program and the achievement of.
Limitations: This research only reviewed the effectiveness of BUMDes Sehati in Nekmese village, Kupang Regency.
Contribution: This research becomes scientific information for public administration science.
Keywords: Effectiveness, BUMDe
Quantum Signatures of The Classical Disconnection Border
A quantum Heisenberg model with anisotropic coupling and all-to-all
interaction has been analyzed using the Bose-Einstein statistics. In
Ref.\cite{jsp} the existence of a classical energy disconnection border (EDB)
in the same kind of models has been demonstrated. We address here the problem
to find quantum signatures of the EDB. An independent definition of a quantum
disconnection border, motivated by considerations strictly valid in the quantum
regime is given. We also discuss the dynamical relevance of the quantum border
with respect to quantum magnetic reversal. Contrary to the classical case the
magnetization can flip even below the EDB through Macroscopic Quantum
Tunneling. We evaluate the time scale for magnetic reversal from statistical
and spectral properties, for a small number of particles and in the
semiclassical limit.Comment: 5 pages, 5 figure
Reflectionless analytic difference operators I. algebraic framework
We introduce and study a class of analytic difference operators admitting
reflectionless eigenfunctions. Our construction of the class is patterned after
the Inverse Scattering Transform for the reflectionless self-adjoint
Schr\"odinger and Jacobi operators corresponding to KdV and Toda lattice
solitons
Chaos and Noise in a Truncated Toda Potential
Results are reported from a numerical investigation of orbits in a truncated
Toda potential which is perturbed by weak friction and noise. Two significant
conclusions are shown to emerge: (1) Despite other nontrivial behaviour,
configuration, velocity, and energy space moments associated with these
perturbations exhibit a simple scaling in the amplitude of the friction and
noise. (2) Even very weak friction and noise can induce an extrinsic diffusion
through cantori on a time scale much shorter than that associated with
intrinsic diffusion in the unperturbed system.Comment: 10 pages uuencoded PostScript (figures included), (A trivial
mathematical error leading to an erroneous conclusion is corrected
Supersonic crack propagation in a class of lattice models of Mode III brittle fracture
We study a lattice model for mode III crack propagation in brittle materials
in a stripe geometry at constant applied stretching. Stiffening of the material
at large deformation produces supersonic crack propagation. For large
stretching the propagation is guided by well developed soliton waves. For low
stretching, the crack-tip velocity has a universal dependence on stretching
that can be obtained using a simple geometrical argument.Comment: 4 pages, 3 figure
Fission yeast 26S proteasome mutants are multi-drug resistant due to stabilization of the pap1 transcription factor
Here we report the result of a genetic screen for mutants resistant to the microtubule poison methyl benzimidazol-2-yl carbamate (MBC) that were also temperature sensitive for growth. In total the isolated mutants were distributed in ten complementation groups. Cloning experiments revealed that most of the mutants were in essential genes encoding various 26S proteasome subunits. We found that the proteasome mutants are multi-drug resistant due to stabilization of the stress-activated transcription factor Pap1. We show that the ubiquitylation and ultimately the degradation of Pap1 depend on the Rhp6/Ubc2 E2 ubiquitin conjugating enzyme and the Ubr1 E3 ubiquitin-protein ligase. Accordingly, mutants lacking Rhp6 or Ubr1 display drug-resistant phenotypes
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