3,463 research outputs found
Dark matter detection in focus point supersymmetry
We determine the prospects for direct and indirect detection of thermal relic neutralinos in supersymmetric theories with multi-TeV squarks and sleptons. We consider the concrete example of the focus point region of minimal supergravity, but our results are generically valid for all models with decoupled scalars and mixed Bino-Higgsino or Higgsino-like dark matter. We determine the parameter space consistent with a 125 GeV Higgs boson including 3-loop corrections in the calculation of the Higgs mass. These corrections increase m_h by 1–3 GeV, lowering the preferred scalar mass scale and decreasing the fine-tuning measure in these scenarios. We then systematically examine prospects for dark matter direct and indirect detection. Direct detection constraints do not exclude these models, especially for μ<0. At the same time, the scenario generically predicts spin-independent signals just beyond current bounds. We also consider indirect detection with neutrinos, gamma rays, antiprotons, and antideuterons. Current IceCube neutrino constraints are competitive with direct detection, implying bright prospects for complementary searches with both direct and indirect detection
Reliability, Effect Size, and Responsiveness and Intraclass Correlation of Health Status Measures Used in Randomized and Cluster-Randomized Trials
Background: New health status instruments are described by psychometric properties, such as Reliability, Effect Size, and Responsiveness. For cluster-randomized trials, another important statistic is the Intraclass Correlation for the instrument within clusters. Studies using better instruments can be performed with smaller sample sizes, but better instruments may be more expensive in terms of dollars, lost opportunities, or poorer data quality due to the response burden of longer instruments. Investigators often need to estimate the psychometric properties of a new instrument, or of an established instrument in a new setting. Optimal sample sizes for estimating these properties have not been studied in detail.
Methods: We examined the power of a two-sample test as a function of the Reliability, Effect Size, Responsiveness, and Intraclass Correlation of the instrument. We calculated the “cost-effectiveness” of using a 1-item versus a 5-item measure of mental health status. We also used simulation to determine formulas for the sample size needed to estimate the psychometric statistics accurately.
Findings: Under the usual model for measurement error, the psychometric statistics are all functions of the same error term. In randomized trials, a poorer instrument can achieve the desired power if the number of persons per treatment group is increased. In cluster-randomized trials, adequate power may be obtained by increasing the number of clusters per treatment group (and often the number of persons per cluster), as well as by choosing a better instrument. The 1-item measure of mental health status may be more cost-effective than the 5-item measure in some settings. Most published psychometric values are situation-specific. Very large samples are required to estimate Responsiveness and the Intraclass Correlation accurately.
Conclusion: If the goal is to diagnose or refer individual patients, an instrument with high Validity and Reliability is needed. In settings where the sample sizes can be increased easily, less reliable instruments may be cost-effective. It is likely that many values of published psychometric statistics were derived from samples too small to provide accurate values, or are importantly specific to the setting in which they were derived.
Note: A paper based on some of the material in this technical report has been published. (Diehr P, Chen L, Patrick D, Feng Z, Yasui Y. Reliability, effect size, and responsiveness of health status measures in the design of randomized and cluster-randomized trials. Contemporary Clinical Trials. 2005; 26:45-58. B). That paper does not include the material on estimating the sample size required to provide an accurate estimate of the reliability of a new instrument. That material is included in this technical report
Sensory afferents use different coding strategies for heat and cold
Primary afferents transduce environmental stimuli
into electrical activity that is transmitted centrally to
be decoded into corresponding sensations. However, it remains unknown how afferent populations
encode different somatosensory inputs. To address
this, we performed two-photon Ca2+ imaging from
thousands of dorsal root ganglion (DRG) neurons in
anesthetized mice while applying mechanical and
thermal stimuli to hind paws. We found that approximately half of all neurons are polymodal and that
heat and cold are encoded very differently. As temperature increases, more heating-sensitive neurons
are activated, and most individual neurons respond
more strongly, consistent with graded coding at population and single-neuron levels, respectively. In
contrast, most cooling-sensitive neurons respond
in an ungraded fashion, inconsistent with graded
coding and suggesting combinatorial coding, based
on which neurons are co-activated. Although individual neurons may respond to multiple stimuli, our results show that different stimuli activate distinct
combinations of diversely tuned neurons, enabling
rich population-level coding
Magnetic Quantum Tunneling: Insights from Simple Molecule-Based Magnets
This article takes a broad view of the understanding of magnetic bistability
and magnetic quantum tunneling in single-molecule magnets (SMMs), focusing on
three families of relatively simple, low-nuclearity transition metal clusters:
spin S = 4 Ni4, Mn(III)3 (S = 2 and 6) and Mn(III)6 (S = 4 and 12). The Mn(III)
complexes are related by the fact that they contain triangular Mn3 units in
which the exchange may be switched from antiferromagnetic to ferromagnetic
without significantly altering the coordination around the Mn(III) centers,
thereby leaving the single-ion physics more-or-less unaltered. This allows for
a detailed and systematic study of the way in which the individual-ion
anisotropies project onto the molecular spin ground state in otherwise
identical low- and high-spin molecules, thus providing unique insights into the
key factors that control the quantum dynamics of SMMs, namely: (i) the height
of the kinetic barrier to magnetization relaxation; and (ii) the transverse
interactions that cause tunneling through this barrier. Numerical calculations
are supported by an unprecedented experimental data set (17 different
compounds), including very detailed spectroscopic information obtained from
high-frequency electron paramagnetic resonance and low-temperature hysteresis
measurements. Diagonalization of the multi-spin Hamiltonian matrix is necessary
in order to fully capture the interplay between exchange and local anisotropy,
and the resultant spin-state mixing which ultimately gives rise to the
tunneling matrix elements in the high symmetry SMMs (ferromagnetic Mn3 and
Ni4). The simplicity (low-nuclearity, high-symmetry, weak disorder, etc..) of
the molecules highlighted in this study proves to be of crucial importance.Comment: 32 pages, incl. 6 figure
final safety tolerability and seizure outcomes in patients with focal epilepsy treated with adjunctive perampanel for up to 4 years in an open label extension of phase iii randomized trials study 307
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Genetic Diversity and Virulence Potential of Shiga Toxin-Producing Escherichia coli O113:H21 Strains Isolated from Clinical, Environmental, and Food Sources
Shiga toxin-producing Escherichia coli strains of serotype O113:H21 have caused severe human diseases, but they are unusual in that they do not produce adherence factors coded by the locus of enterocyte effacement. Here, a PCR microarray was used to characterize 65 O113:H21 strains isolated from the environment, food, and clinical infections from various countries. in comparison to the pathogenic strains that were implicated in hemolytic-uremic syndrome in Australia, there were no clear differences between the pathogens and the environmental strains with respect to the 41 genetic markers tested. Furthermore, all of the strains carried only Shiga toxin subtypes associated with human infections, suggesting that the environmental strains have the potential to cause disease. Most of the O113:H21 strains were closely related and belonged in the same clonal group (ST-223), but CRISPR analysis showed a great degree of genetic diversity among the O113:H21 strains.French Joint Ministerial Program of R&D against CBRNE RisksFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Food & Drug Adm, Div Microbiol, College Pk, MD 20740 USAFrench Agcy Food Environm & Occupat Hlth & Safety, Lab Food Safety, Maisons Alfort, FranceFood & Drug Adm, Div Mol Biol, Laurel, MD USAUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilFed Inst Risk Assessment, Natl Reference Lab Escherichia coli, Berlin, GermanyInst Nacl Enfermedades Infecciosas ANLIS Dr Carlo, Serv Fisiopatogenia, Buenos Aires, DF, ArgentinaUniv Melbourne, Peter Doherty Inst Infect & Immun, Dept Microbiol & Immunol, Melbourne, Vic, AustraliaUniv Adelaide, Res Ctr Infect Dis, Sch Mol & Biomed Sci, Adelaide, SA, AustraliaUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilFrench Joint Ministerial Program of R&D against CBRNE Risks: C17609-2Web of Scienc
Higgs friends and counterfeits at hadron colliders
We consider the possibility of "Higgs counterfeits" - scalars that can be
produced with cross sections comparable to the SM Higgs, and which decay with
identical relative observable branching ratios, but which are nonetheless not
responsible for electroweak symmetry breaking. We also consider a related
scenario involving "Higgs friends," fields similarly produced through gg fusion
processes, which would be discovered through diboson channels WW, ZZ, gamma
gamma, or even gamma Z, potentially with larger cross sections times branching
ratios than for the Higgs. The discovery of either a Higgs friend or a Higgs
counterfeit, rather than directly pointing towards the origin of the weak
scale, would indicate the presence of new colored fields necessary for the
sizable production cross section (and possibly new colorless but electroweakly
charged states as well, in the case of the diboson decays of a Higgs friend).
These particles could easily be confused for an ordinary Higgs, perhaps with an
additional generation to explain the different cross section, and we emphasize
the importance of vector boson fusion as a channel to distinguish a Higgs
counterfeit from a true Higgs. Such fields would naturally be expected in
scenarios with "effective Z's," where heavy states charged under the SM produce
effective charges for SM fields under a new gauge force. We discuss the
prospects for discovery of Higgs counterfeits, Higgs friends, and associated
charged fields at the LHC.Comment: 27 pages, 5 figures. References added and typos fixe
Rewritable nanoscale oxide photodetector
Nanophotonic devices seek to generate, guide, and/or detect light using
structures whose nanoscale dimensions are closely tied to their functionality.
Semiconducting nanowires, grown with tailored optoelectronic properties, have
been successfully placed into devices for a variety of applications. However,
the integration of photonic nanostructures with electronic circuitry has always
been one of the most challenging aspects of device development. Here we report
the development of rewritable nanoscale photodetectors created at the interface
between LaAlO3 and SrTiO3. Nanowire junctions with characteristic dimensions
2-3 nm are created using a reversible AFM writing technique. These nanoscale
devices exhibit a remarkably high gain for their size, in part because of the
large electric fields produced in the gap region. The photoconductive response
is gate-tunable and spans the visible-to-near-infrared regime. The ability to
integrate rewritable nanoscale photodetectors with nanowires and transistors in
a single materials platform foreshadows new families of integrated
optoelectronic devices and applications.Comment: 5 pages, 5 figures. Supplementary Information 7 pages, 9 figure
Spatial transcriptomics reveals a role for sensory nerves in preserving cranial suture patency through modulation of BMP/TGF-β signaling
: The patterning and ossification of the mammalian skeleton requires the coordinated actions of both intrinsic bone morphogens and extrinsic neurovascular signals, which function in a temporal and spatial fashion to control mesenchymal progenitor cell (MPC) fate. Here, we show the genetic inhibition of tropomyosin receptor kinase A (TrkA) sensory nerve innervation of the developing cranium results in premature calvarial suture closure, associated with a decrease in suture MPC proliferation and increased mineralization. In vitro, axons from peripheral afferent neurons derived from dorsal root ganglions (DRGs) of wild-type mice induce MPC proliferation in a spatially restricted manner via a soluble factor when cocultured in microfluidic chambers. Comparative spatial transcriptomic analysis of the cranial sutures in vivo confirmed a positive association between sensory axons and proliferative MPCs. SpatialTime analysis across the developing suture revealed regional-specific alterations in bone morphogenetic protein (BMP) and TGF-β signaling pathway transcripts in response to TrkA inhibition. RNA sequencing of DRG cell bodies, following direct, axonal coculture with MPCs, confirmed the alterations in BMP/TGF-β signaling pathway transcripts. Among these, the BMP inhibitor follistatin-like 1 (FSTL1) replicated key features of the neural-to-bone influence, including mitogenic and anti-osteogenic effects via the inhibition of BMP/TGF-β signaling. Taken together, our results demonstrate that sensory nerve-derived signals, including FSTL1, function to coordinate cranial bone patterning by regulating MPC proliferation and differentiation in the suture mesenchyme
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