799 research outputs found
YARN PARAMETERS INFLUENCING THE KNITTABILITY OF HIGH-GRADE SPUN YARNS
Noncollinear magnetism can play an important role in multiferroic materials but is relatively understudied in oxide heterostructures compared to their bulk counterparts. Using variable temperature magnetometry and neutron diffraction, we demonstrate the presence of helical magnetic ordering in CaMn7O12 and Ca1−xSrxMn7O12
(for x up to 0.51) thin films. Consistent with bulk Ca1−xSrxMn7O12, the net magnetization increases with Sr
doping. Neutron diffraction confirms that the helical magnetic structure remains incommensurate at all values
of x, while the fundamental magnetic wavevector increases upon Sr substitution. This result demonstrates a
chemical-based approach for tuning helical magnetism in quadruple perovskite films and enables future studies
of strain and interfacial effects on helimagnetism in oxide heterostructures
On the Complexity of Scheduling in Wireless Networks
We consider the problem of throughput-optimal scheduling in wireless networks subject to interference constraints. We model the interference using a family of K-hop interference models, under which no two links within a K-hop distance can successfully transmit at the same time. For a given K, we can obtain a throughput-optimal scheduling policy by solving the well-known maximum weighted matching problem. We show that for K > 1, the resulting problems are NP-Hard that cannot be approximated within a factor that grows polynomially with the number of nodes. Interestingly, for geometric unit-disk graphs that can be used to describe a wide range of wireless networks, the problems admit polynomial time approximation schemes within a factor arbitrarily close to 1. In these network settings, we also show that a simple greedy algorithm can provide a 49-approximation, and the maximal matching scheduling policy, which can be easily implemented in a distributed fashion, achieves a guaranteed fraction of the capacity region for "all K." The geometric constraints are crucial to obtain these throughput guarantees. These results are encouraging as they suggest that one can develop low-complexity distributed algorithms to achieve near-optimal throughput for a wide range of wireless networksopen1
Quantum physics in inertial and gravitational fields
Covariant generalizations of well-known wave equations predict the existence
of inertial-gravitational effects for a variety of quantum systems that range
from Bose-Einstein condensates to particles in accelerators. Additional effects
arise in models that incorporate Born reciprocity principle and the notion of a
maximal acceleration. Some specific examples are discussed in detail.Comment: 25 pages,1 figure,to appear in "Relativity in Rotating Frame
Discovery of SQSTM1/p62-dependent P-bodies that regulate the NLRP3 inflammasome
Autophagy and ribonucleoprotein granules, such as P-bodies (PBs) and stress granules, represent vital stress responses to maintain cellular homeostasis. SQSTM1/p62 phase-separated droplets are known to play critical roles in selective autophagy; however, it is unknown whether p62 can exist as another form in addition to its autophagic droplets. Here, we found that, under stress conditions, including proteotoxicity, endotoxicity, and oxidation, autophagic p62 droplets are transformed to a type of enlarged PBs, termed p62-dependent P-bodies (pd-PBs). p62 phase separation is essential for the nucleation of pd-PBs. Mechanistically, pd-PBs are triggered by enhanced p62 droplet formation upon stress stimulation through the interactions between p62 and DDX6, a DEAD-box ATPase. Functionally, pd-PBs recruit the NLRP3 inflammasome adaptor ASC to assemble the NLRP3 inflammasome and induce inflammation-associated cytotoxicity. Our study shows that p62 droplet-to-PB transformation acts as a stress response to activate the NLRP3 inflammasome process, suggesting that persistent pd-PBs lead to NLRP3-dependent inflammation toxicity
Is Microsporidial keratitis an emerging cause of stromal keratitis? – a case series study
BACKGROUND: Microsporidial keratitis is a rare cause of stromal keratitis. We present a series of five cases of microsporidial keratitis from a single centre in southern India with microbiologic and histopathologic features. CASE PRESENTATION: Patient charts of five cases of microsporidial stromal keratitis diagnosed between January 2002 and June 2004 were reviewed retrospectively for clinical data, microbiologic and histopathologic data. The presence of microsporidia was confirmed by special stains on corneal scrapings and/or corneal tissues, and electron microscopy. All patients were immunocompetent with a preceding history of trauma in three. Four patients presented with unilateral, small, persisting deep stromal infiltrates, of uncertain etiology, in the cornea, which were not responding to conventional antimicrobial treatment and required penetrating keratoplasty in three. Fifth case was unsuspected and underwent keratoplasty for post-traumatic scar. Three of five cases were diagnosed on corneal scrapings, prior to keratoplasty, while two were diagnosed only on histology. The microsporidia appeared as oval well defined bodies with dense staining at one pole. None of the patients showed recurrence following keratoplasty. CONCLUSION: Microsporidia, though rare, should be suspected in chronic culture-negative stromal keratitis. Organisms could lie dormant without associated inflammation
Study of the Decays B0 --> D(*)+D(*)-
The decays B0 --> D*+D*-, B0 --> D*+D- and B0 --> D+D- are studied in 9.7
million Y(4S) --> BBbar decays accumulated with the CLEO detector. We determine
Br(B0 --> D*+D*-) = (9.9+4.2-3.3+-1.2)e-4 and limit Br(B0 --> D*+D-) < 6.3e-4
and Br(B0 --> D+D-) < 9.4e-4 at 90% confidence level (CL). We also perform the
first angular analysis of the B0 --> D*+D*- decay and determine that the
CP-even fraction of the final state is greater than 0.11 at 90% CL. Future
measurements of the time dependence of these decays may be useful for the
investigation of CP violation in neutral B meson decays.Comment: 21 pages, 5 figures, submitted to Phys. Rev.
Measurements of B --> D_s^{(*)+} D^{*(*)} Branching Fractions
This article describes improved measurements by CLEO of the and branching fractions, and first evidence
for the decay , where
represents the sum of the , , and
L=1 charm meson states. Also reported is the first
measurement of the polarization in the decay . A partial reconstruction technique, employing only the fully
reconstructed and slow pion from the decay, enhances sensitivity. The observed branching fractions are
, , and , where the first error is statistical,
the second systematic, and the third is due to the uncertainty in the branching fraction. The measured longitudinal
polarization, , is consistent with
the factorization prediction of 54%.Comment: 26 pages (LaTeX), 15 figures. To be submitted to PR
Improved Measurement of the Pseudoscalar Decay Constant
We present a new determination of the Ds decay constant, f_{Ds} using 5
million continuum charm events obtained with the CLEO II detector. Our value is
derived from our new measured ratio of widths for Ds -> mu nu/Ds -> phi pi of
0.173+/- 0.021 +/- 0.031. Taking the branching ratio for Ds -> phi pi as (3.6
+/- 0.9)% from the PDG, we extract f_{Ds} = (280 +/- 17 +/- 25 +/- 34){MeV}. We
compare this result with various model calculations.Comment: 23 page postscript file, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Precise Measurement of B^{0}\to \bar{B^{0} Mixing Parameters at the S)$
We describe a measurement of B^0-B^0bar mixing parameters exploiting a method
of partial reconstruction of the decay chains B0 -> D^{*-}\pi^+ and B0 ->
D^{*-}\rho^+. Using 9.6 x 10^6 BBbar pairs collected at the Cornell Electron
Storage Ring, we find \chi_d = 0.198 +- 0.013 +- 0.014, |y_d|<0.41 at 95%
confidence level, and |Re(\epsilon_B)|<0.034 at 95% confidence level.Comment: 11 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
First Observation of and Decays
We have observed new channels for decays with an in the final
state. We study 3-prong tau decays, using the and
\eta\to 3\piz decay modes and 1-prong decays with two \piz's using the
channel. The measured branching fractions are
\B(\tau^{-}\to \pi^{-}\pi^{-}\pi^{+}\eta\nu_{\tau})
=(3.4^{+0.6}_{-0.5}\pm0.6)\times10^{-4} and \B(\tau^{-}\to
\pi^{-}2\piz\eta\nu_{\tau}
=(1.4\pm0.6\pm0.3)\times10^{-4}. We observe clear evidence for
substructure and measure \B(\tau^{-}\to
f_1\pi^{-}\nu_{\tau})=(5.8^{+1.4}_{-1.3}\pm1.8)\times10^{-4}. We have also
searched for production and obtain 90% CL upper limits
\B(\tau^{-}\to \pi^{-}\eta'\nu_\tau)<7.4\times10^{-5} and \B(\tau^{-}\to
\pi^{-}\piz\eta'\nu_\tau)<8.0\times10^{-5}.Comment: 11 page postscript file, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
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