1,001 research outputs found
Coarse coherence of metric spaces and groups and its permanence properties
We introduce properties of metric spaces and, specifically, finitely
generated groups with word metrics which we call coarse coherence and coarse
regular coherence. They are geometric counterparts of the classical algebraic
notion of coherence and the regular coherence property of groups defined and
studied by F. Waldhausen. The new properties can be defined in the general
context of coarse metric geometry and are coarse invariants. In particular,
they are quasi-isometry invariants of spaces and groups. We show that coarse
regular coherence implies weak regular coherence, a weakening of regular
coherence by G. Carlsson and the first author. The latter was introduced with
the same goal as Waldhausen's, in order to perform computations of algebraic
K-theory of group rings. However, all groups known to be weakly regular
coherent are also coarsely regular coherent. The new framework allows us to
prove structural results by developing permanence properties, including the
particularly important fibering permanence property, for coarse regular
coherence.Comment: 11 page
Tariffs as Insurance: Optimal Commercial Policy When Domestic Markets Are Incomplete
Free trade is not optimal for a small country that faces uncertain terms of trade if some factors are immobile - ex post, and markets for contingent claims are incomplete. The government can improve social welfare by using commercial policy that serves as a partial substitute for missing insurance markets. Using a combination of analytical and simulation techniques we demonstrate that optimal policy for this purpose will often have an anti-trade bias. We also show that the usual preference by economists for factor or product taxes and subsidies over tariffs and export subsidies may not be justified in this context.
Interpreting the time-dependent CP asymmetry in
Flavor SU(3) is used for studying the time-dependent CP asymmetry in by relating this process to and . We calculate correlated bounds on and
, with maximal magnitudes of 0.2 and 0.3, where and
are coefficients of and in the
asymmetry. Stronger upper limits on are expected to reduce
these bounds and to imply nonzero lower limits on these observables. The
asymmetry is studied as a function of a strong phase and the weak phase
.Comment: 11 pages, 2 figures, to be published in Phys. Lett. B. Some equations
corrected leading to small changes in figure
MalStone: Towards A Benchmark for Analytics on Large Data Clouds
Developing data mining algorithms that are suitable for cloud computing
platforms is currently an active area of research, as is developing cloud
computing platforms appropriate for data mining. Currently, the most common
benchmark for cloud computing is the Terasort (and related) benchmarks.
Although the Terasort Benchmark is quite useful, it was not designed for data
mining per se. In this paper, we introduce a benchmark called MalStone that is
specifically designed to measure the performance of cloud computing middleware
that supports the type of data intensive computing common when building data
mining models. We also introduce MalGen, which is a utility for generating data
on clouds that can be used with MalStone
A Case of Steroid-Responsive Encephalopathy
Hashimoto\u27s encephalopathy (HE), also known as steroid-responsive encephalopathy, is associated with autoimmune-mediated thyroiditis. Onset is typically gradual often with evolution over the course of months. Characteristic symptoms include impaired concentration and memory, delusions, hallucinations, personality changes, incoordination, tremor, hemiparesis, seizures, and speech difficulties. Diagnosis is predicated upon discovery of elevated anti-thyroid antibodies, specifically anti-thyroid peroxidase (TPO) or anti-M antibodies. Some patients may also present with subclinical hypothyroidism but many are euthyroid. Of note, neither thyroid function tests or antibody titers correlate with disease severity. Other common laboratory findings include elevations in sedimentation rate, liver enzymes, and cerebrospinal fluid (CSF) protein. Radiological work-up, including cerebral angiography, is often normal. Successful treatment includes administration of steroids and/or intravenous immunoglobulin (IVIg) or plasmapheresis. We describe a case of a 74-year-old male who presented for evaluation of abrupt onset confusion ultimately determined to be a consequence of autoimmune-mediated thyroiditis
Differences in hearing acuity among “normal-hearing” young adults modulate the neural basis for speech comprehension
AbstractIn this paper, we investigate how subtle differences in hearing acuity affect the neural systems supporting speech processing in young adults. Auditory sentence comprehension requires perceiving a complex acoustic signal and performing linguistic operations to extract the correct meaning. We used functional MRI to monitor human brain activity while adults aged 18–41 years listened to spoken sentences. The sentences varied in their level of syntactic processing demands, containing either a subject-relative or object-relative center-embedded clause. All participants self-reported normal hearing, confirmed by audiometric testing, with some variation within a clinically normal range. We found that participants showed activity related to sentence processing in a left-lateralized frontotemporal network. Although accuracy was generally high, participants still made some errors, which were associated with increased activity in bilateral cingulo-opercular and frontoparietal attention networks. A whole-brain regression analysis revealed that activity in a right anterior middle frontal gyrus (aMFG) component of the frontoparietal attention network was related to individual differences in hearing acuity, such that listeners with poorer hearing showed greater recruitment of this region when successfully understanding a sentence. The activity in right aMFGs for listeners with poor hearing did not differ as a function of sentence type, suggesting a general mechanism that is independent of linguistic processing demands. Our results suggest that even modest variations in hearing ability impact the systems supporting auditory speech comprehension, and that auditory sentence comprehension entails the coordination of a left perisylvian network that is sensitive to linguistic variation with an executive attention network that responds to acoustic challenge.</jats:p
Complete Genome Sequences of Bacillus subtilis subsp. subtilis Laboratory Strains JH642 (AG174) and AG1839
The Gram-positive bacterium Bacillus subtilis is widely used for studies of cellular and molecular processes. We announce the complete genomic sequences of strain AG174, our stock of the commonly used strain JH642, and strain AG1839, a derivative that contains a mutation in the replication initiation gene dnaB and a linked Tn917.National Institute of General Medical Sciences (U.S.) (NIH award number GM41934
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