12,291 research outputs found
Miniature vibration isolator Patent
Miniature vibration isolator utilizing elastic tubing materia
A combination of soluble helper factors bypasses the requirement for stimulator cells and induces nonspecific cytotoxic T cell responses
The specificity of cytotoxic T lymphocyte (CTL) responses generated in the presence of lymphokines was studied. Thymic responder cells were activated in the presence of stimulator cells that differed in their metabolic activity. After 5 days of culture, the cytotoxic response was estimated in a 4-h 51Cr-release test. Coculture of thymic responders with irradiated splenic stimulator cells in the presence of interleukin 2(IL 2) led to preferential cytolysis of target cells that expressed the same histocompatibility antigens as the cells used for sensitization. Addition of T cell cytotoxicity-inducing factor 1 (TCF1), however, to those cultures made the presence of stimulator cells unnecessary and induced cytotoxic responses against all target cells tested, including target cells syngeneic to the responder cells. This activation was neither due to contaminating mitogen nor to the effect of heterologous serum in the assay system. The conclusion of these findings was that either polyclonal activation of CTL was induced by TCF1 or that some specific CTL clones differentiated into unrestricted killer cells under the influence of TCF1
Canister closing device Patent
Design and characteristics of device for closing canisters under high vacuum condition
Requirement of endogenous tumor necrosis factor/cachectin for recovery from experimental peritonitis
By intrasplenic immunization we raised a rat mAb (mAb V1q; IgG2a, kappa) with a potent neutralizing activity against natural mouse TNF (1 microgram/ml mAb V1q/100 U/ml TNF). mAb V1q was used to study the role of endogenous TNF in experimental peritonitis induced by sublethal cecal ligation and puncture. mAb V1q persisted for over 5 days in the serum of mice injected with 100 micrograms of the antibody and, therefore, proved useful for in vivo experiments. As little as 20 micrograms mAb V1q/mouse prevented lethal shock of the animals by 400 micrograms LPS/mouse. In sublethal cecal ligation and puncture i.p. injection of mAb V1q directly and up to 8 h after induction of experimental peritonitis lead to death of the animals within 1 to 3 days. The lethal effect of mAb V1q was compensated by injection of recombinant mouse TNF. Similar mAb V1q effects as in immunocompetent mice were shown in severe combined immune deficiency mice deficient of mature functional B and T cells. Taken together, these data suggest that during the early phase of peritonitis endogenous TNF may stimulate nonlymphoid cells such as granulocytes, macrophages, platelets, and fibroblasts to ingest bacteria and to localize inflammation, respectively. These beneficial effects of TNF may determine survival. Thus, our data may have implications for the therapeutic management of a beginning peritonitis
Novel Spin and Statistical Properties of Nonabelian Vortices
We study the statistics of vortices which appear in (2+1)--dimensional
spontaneously broken gauge theories, where a compact group G breaks to a finite
nonabelian subgroup H. Two simple models are presented. In the first, a quantum
state which is symmetric under the interchange of a pair of indistinguishable
vortices can be transformed into an antisymmetric state after the passage
through the system of a third vortex with an appropriate -flux element.
Further, there exist states containing two indistinguishable spinless vortices
which obey Fermi statistics. These results generalize to loops of nonabelian
cosmic string in 3+1 dimensions. In the second model, fractional analogues of
the above behaviors occur. Also, composites of vortices in this theory may
possess fractional ``Cheshire spin'' which can be changed by passing an
additional vortex through the system.Comment: 11 pages, UICHEP-TH/92-15; FERMILAB-PUB-92/233-T; SLAC-PUB-588
CP Tagged Decays at SuperBaBar
We explore the possibility of measuring the CKM parameter gamma using CP
tagged decays at a very high luminosity e+e- B Factory. A new collider capable
of integrating as much as 10 inverse attobarns per year is being discussed as a
possible future for SLAC beyond the current PEP-II program, and could also be
in the future of KEK. In two years of operation, it could be possible for a
successor to BaBar or Belle to accumulate a sample of one million CP tagged B
decays. We find that a theoretically clean extraction of gamma with uncertainty
less than 5 degrees may be achievable in the analysis of such a data set.Comment: 14 pages, 4 figures; minimal revisions for version to appear in
Physical Review D, all formulas and conclusions unchange
Spin Coherence During Optical Excitation of a Single NV Center in Diamond
We examine the quantum spin state of a single nitrogen-vacancy (NV) center in
diamond at room temperature as it makes a transition from the orbital
ground-state (GS) to the orbital excited-state (ES) during non-resonant optical
excitation. While the fluorescence read-out of NV-center spins relies on
conservation of the longitudinal spin projection during optical excitation, the
question of quantum phase preservation has not been examined. Using Ramsey
measurements and quantum process tomography, we establish limits on NV center
spin decoherence induced during optical excitation. Treating the optical
excitation and ES spin precession as a quantum process, we measure a process
fidelity of F=0.87\pm0.03, which includes ES spin dephasing during measurement.
Extrapolation to the moment of optical excitation yields F\approx0.95. This
result demonstrates that ES spin interactions may be used as a resource for
quantum control because the quantum spin state can survive incoherent orbital
transitions.Comment: 12 pages, 3 figure
Strain localization in a shear transformation zone model for amorphous solids
We model a sheared disordered solid using the theory of Shear Transformation
Zones (STZs). In this mean-field continuum model the density of zones is
governed by an effective temperature that approaches a steady state value as
energy is dissipated. We compare the STZ model to simulations by Shi, et
al.(Phys. Rev. Lett. 98 185505 2007), finding that the model generates
solutions that fit the data,exhibit strain localization, and capture important
features of the localization process. We show that perturbations to the
effective temperature grow due to an instability in the transient dynamics, but
unstable systems do not always develop shear bands. Nonlinear energy
dissipation processes interact with perturbation growth to determine whether a
material exhibits strain localization. By estimating the effects of these
interactions, we derive a criterion that determines which materials exhibit
shear bands based on the initial conditions alone. We also show that the shear
band width is not set by an inherent diffusion length scale but instead by a
dynamical scale that depends on the imposed strain rate.Comment: 8 figures, references added, typos correcte
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