6,367 research outputs found
High-temperature measurements of Q-factor in rotated X-cut quartz resonators
The Q-factors of piezoelectric resonators fabricated from natural and synthetic quartz with a 34 deg rotated X-cut orientation were measured at temperatures up to 325 C. The synthetic material, which was purified by electrolysis, retains a higher enough Q to be suitable for high temperature pressure-transducer applications, whereas the natural quartz is excessively lossy above 200 C for this application. The results are compared to results obtained previously at AT-cut resonators
On the existence of quantum representations for two dichotomic measurements
Under which conditions do outcome probabilities of measurements possess a
quantum-mechanical model? This kind of problem is solved here for the case of
two dichotomic von Neumann measurements which can be applied repeatedly to a
quantum system with trivial dynamics. The solution uses methods from the theory
of operator algebras and the theory of moment problems. The ensuing conditions
reveal surprisingly simple relations between certain quantum-mechanical
probabilities. It also shown that generally, none of these relations holds in
general probabilistic models. This result might facilitate further experimental
discrimination between quantum mechanics and other general probabilistic
theories.Comment: 16+7 pages, presentation improved and minor errors correcte
Early-type Galaxies in the Cluster Abell 2390 at z=0.23
To examine the evolution of the early-type galaxy population in the rich
cluster Abell 2390 at z=0.23 we have gained spectroscopic data of 51 elliptical
and lenticular galaxies with MOSCA at the 3.5 m telescope on Calar Alto
Observatory. This investigation spans both a broad range in luminosity
(-19.3>M_B>-22.3) and uses a wide field of view of 10'x10', therefore the
environmental dependence of different formation scenarios can be analysed in
detail as a function of radius from the cluster centre. Here we present results
on the surface brightness modelling of galaxies where morphological and
structural information is available in the F814W filter aboard the Hubble Space
Telescope (HST) and investigate for this subsample the evolution of the
Fundamental Plane.Comment: 5 pages, 5 figures, to appear in "Carnegie Observatories Astrophysics
Series, Vol. 3: Clusters of Galaxies: Probes of Cosmological Structure and
Galaxy Evolution", ed. J. S. Mulchaey, A. Dressler, and A. Oemler (Pasadena:
Carnegie Observatories,
http://www.ociw.edu/ociw/symposia/series/symposium3/proceedings.html
An entropic approach to local realism and noncontextuality
For any Bell locality scenario (or Kochen-Specker noncontextuality scenario),
the joint Shannon entropies of local (or noncontextual) models define a convex
cone for which the non-trivial facets are tight entropic Bell (or
contextuality) inequalities. In this paper we explore this entropic approach
and derive tight entropic inequalities for various scenarios. One advantage of
entropic inequalities is that they easily adapt to situations like bilocality
scenarios, which have additional independence requirements that are non-linear
on the level of probabilities, but linear on the level of entropies. Another
advantage is that, despite the nonlinearity, taking detection inefficiencies
into account turns out to be very simple. When joint measurements are conducted
by a single detector only, the detector efficiency for witnessing quantum
contextuality can be arbitrarily low.Comment: 12 pages, 8 figures, minor mistakes correcte
Dimensional crossover in quantum critical metallic magnets
Nearly magnetic metals often have layered lattice structures, consisting of
coupled planes. In such a situation, physical properties will display, upon
decreasing temperature or energy, a dimensional crossover from two-dimensional
(2d) to three-dimensional (3d) behavior, which is particularly interesting near
quantum criticality. Here we study this crossover in thermodynamics using a
suitably generalized Landau-Ginzburg-Wilson approach to the critical behavior,
combined with renormalization group techniques. We focus on two experimentally
relevant cases: the crossover from a 2d to a 3d antiferromagnet, and the
crossover from a 2d ferromagnet to a 3d antiferromagnet. We discuss the
location of phase boundary and crossover lines and determine the crossover
functions for important thermodynamic quantities. As naive scaling does not
apply at and above the upper critical dimension, two crossover scales arise
which can be associated with separate dimensional crossovers of classical and
quantum fluctuations, respectively. In particular, we find an intermediate
regime with novel power laws where the quantum fluctuations still have a 2d and
the classical fluctuations already have a 3d character. For the
ferromagnet-to-antiferromagnet crossover, the mismatch of the dynamical
exponents between the 2d and 3d regimes leads to an even richer crossover
structure, with an interesting 2d non-critical regime sandwiched between two
critical regimes. For all cases, we find that thermal expansion and
compressibility are particularly sensitive probes of the dimensional crossover.
Finally, we relate our results to experiments on the quantum critical
heavy-fermion metals CeCu(6-x)Au(x), YbRh(2)Si(2) and CeCoIn(5).Comment: 18 pages, 8 figures, published versio
IL-33 signaling regulates innate and adaptive immunity to Cryptococcus neoformans.
Susceptibility to progressive infection with the fungus Cryptococcus neoformans is associated with an allergic pattern of lung inflammation, yet the factors that govern this host response are not clearly understood. Using a clinically relevant mouse model of inhalational infection with virulent C. neoformans H99, we demonstrate a role for IL-33-dependent signaling in host immune defense. Infection of BALB/c mice with 10(4) CFU of C. neoformans H99 caused a time-dependent induction of IL-33 with accumulation of type 2 pulmonary innate lymphoid cells and alternatively activated macrophages in the lungs as well as Th2-polarized CD4(+) T cells in draining lymph nodes. IL-33R subunit T1/ST2-deficient (T1/ST2(-/-)) mice infected with C. neoformans H99 had improved survival with a decreased fungal burden in the lungs, spleen, and brain, compared with wild-type mice. Signaling through T1/ST2 was required for the accumulation and early production of IL-5 and IL-13 by lung type 2 pulmonary innate lymphoid cells. Further analysis of T1/ST2(-/-) mice revealed increased fungicidal exudate macrophages in the lungs and decreased C. neoformans-specific Th2 cells in the mediastinal lymph nodes. T1/ST2 deficiency also diminished goblet cell hyperplasia, mucus hypersecretion, bronchoalveolar lavage eosinophilia, alternative activation of macrophages, and serum IgE. These observations demonstrate that IL-33-dependent signaling contributes to the expansion of innate type 2 immunity and subsequent Th2-biased lung immunopathology that facilitates C. neoformans growth and dissemination
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Structural characterization of proteoglycans produced by testicular peritubular cells and Sertoli cells
The structural characteristics of proteoglycans produced by seminiferous peritubular cells and by Sertoli cells are defined. Peritubular cells secrete two proteoglycans designated PC I and PC II. PC I is a high molecular mass protein containing chondroitin glycosaminoglycan (GAG) chains (maximum 70 kDa). PC II has a protein core of 45 kDa and also contains chondroitin GAG chains (maximum 70 kDa). Preliminary results imply that PC II may be a degraded or processed form of PC I. A cellular proteoglycan associated with the peritubular cells is described which has properties similar to those of PC I. Sertoli cells secrete two different proteoglycans, designated SC I and SC II. SC I is a large protein containing both chondroitin (maximum 62 kDa) and heparin (maximum 15 kDa) GAG chains. Results obtained suggest that this novel proteoglycan contains both chondroitin and heparin GAG chains bound to the same core protein. SC II has a 50-kDa protein core and contains chondroitin (maximum 25 kDa) GAG chains. A proteoglycan obtained from extracts of Sertoli cells is described which contains heparin (maximum 48 kDa) GAG chains. In addition, Sertoli cells secrete a sulfoprotein, SC III, which is not a proteoglycan. SC III has properties similar to those of a major Sertoli cell-secreted protein previously defined as a dimeric acidic glycoprotein. The stimulation by follicle-stimulating hormone of the incorporation of [35S]SO2(-4) into moieties secreted by Sertoli cells is shown to represent an increased production or sulfation of SC III (i.e. dimeric acidic glycoprotein), and not an increased production or sulfation of proteoglycans. Results are discussed in relation to the possible functions of proteoglycans in the seminiferous tubule
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