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Comparing ligo merger rate observations with theory: distribution of star-forming conditions
Within the next decade, ground based gravitational wave detectors are in principle capable of determining the compact object merger rate per unit volume of the local universe to better than 20% with more than 30 detections. Though these measurements can constrain our models of stellar, binary, and cluster evolution in the nearby present-day and ancient universe, we argue that the universe is sufficiently heterogeneous (in age and metallicity distribution at least) and that merger rates predicted by these models can be sufficiently sensitive to those heterogeneities so that a fair comparison of models per unit similar star forming mass necessarily introduces at least an additional 30%--50% systematic error into any constraints on compact binary evolution models. Without adding new electromagnetic constraints on massive binary evolution or relying on more information from each merger (e.g. , binary masses and spins), as few as the {approx_equal}5 merger detections could exhaust the information available in a naive comparison to merger rate predictions. As a concrete example immediately relevant to analysis of initial and enhanced LIGO results, we use a nearby-universe catalog to demonstrate that no one tracer of stellar content can be consistently used to constrain merger rates without introducing a systematic error of order 0(30%) at 90% confidence (depending on the type of binary involved). For example, though binary black holes typically take many Gyr to merge, binary neutron stars often merge rapidly; different tracers of stellar content are required for these two types. More generally, we argue that theoretical binary evolution can depend sufficiently sensitively on star-forming conditions -- even assuming no uncertainty in binary evolution model -- that the distribution of star forming conditions must be incorporated to reduce the systematic error in merger rate predictions below roughly 40%. We emphasize that the degree of sensitivity to star-forming conditions depends on the binary evolution model and on the amount of relevant variation in star-forming conditions. For example, if after further comparison with electromagnetic and gravitational wave observations future population synthesis models suggest all BH-BH binary mergers occur promptly and therefore are associated with well-studied present-day star formation, the associated composition-related systematic uncertainty could be lower than the pessimistic value quoted above. Further, as gravitational wave detectors will make available many properties of each merger -- binary component masses, spins, and even short GRB associations and host galaxies could be available -- many detections can still be exploited to create high-precision constraints on binary compact object formation models
Tropomyosin controls sarcomere-like contractions for rigidity sensing and suppressing growth on soft matrices
Cells test the rigidity of the extracellular matrix by applying forces to it through integrin adhesions. Recent measurements show that these forces are applied by local micrometre-scale contractions, but how contraction force is regulated by rigidity is unknown. Here we performed high temporal- and spatial-resolution tracking of contractile forces by plating cells on sub-micrometre elastomeric pillars. We found that actomyosin-based sarcomere-like contractile units (CUs) simultaneously moved opposing pillars in net steps of âŒ2.5ânm, independent of rigidity. What correlated with rigidity was the number of steps taken to reach a force level that activated recruitment of α-actinin to the CUs. When we removed actomyosin restriction by depleting tropomyosin 2.1, we observed larger steps and higher forces that resulted in aberrant rigidity sensing and growth of non-transformed cells on soft matrices. Thus, we conclude that tropomyosin 2.1 acts as a suppressor of growth on soft matrices by supporting proper rigidity sensing
TeV physics and the Planck scale
Supersymmetry is one of the best motivated possibilities for new physics at
the TeV scale. However, both concrete string constructions and phenomenological
considerations suggest the possibility that the physics at the TeV scale could
be more complicated than the Minimal Supersymmetric Standard Model (MSSM),
e.g., due to extended gauge symmetries, new vector-like supermultiplets with
non-standard SU(2)xU(1) assignments, and extended Higgs sectors. We briefly
comment on some of these possibilities, and discuss in more detail the class of
extensions of the MSSM involving an additional standard model singlet field.
The latter provides a solution to the problem, and allows significant
modifications of the MSSM in the Higgs and neutralino sectors, with important
consequences for collider physics, cold dark matter, and electroweak
baryogenesis.Comment: 17 pages, 5 figures. To appear in New Journal of Physic
Neutron time-of-flight measurements of charged-particle energy loss in inertial confinement fusion plasmas
Neutron spectra from secondary ^{3}H(d,n)α reactions produced by an implosion of a deuterium-gas capsule at the National Ignition Facility have been measured with order-of-magnitude improvements in statistics and resolution over past experiments. These new data and their sensitivity to the energy loss of fast tritons emitted from thermal ^{2}H(d,p)^{3}H reactions enable the first statistically significant investigation of charged-particle stopping via the emitted neutron spectrum. Radiation-hydrodynamic simulations, constrained to match a number of observables from the implosion, were used to predict the neutron spectra while employing two different energy loss models. This analysis represents the first test of stopping models under inertial confinement fusion conditions, covering plasma temperatures of k_{B}Tâ1-4ââkeV and particle densities of nâ(12-2)Ă10^{24}ââcm^{-3}. Under these conditions, we find significant deviations of our data from a theory employing classical collisions whereas the theory including quantum diffraction agrees with our data
Consensus recommendations for risk stratification in multiple myeloma: report of the International Myeloma Workshop Consensus Panel 2.
A panel of members of the 2009 International Myeloma Workshop developed guidelines for risk stratification in multiple myeloma. The purpose of risk stratification is not to decide time of therapy but to prognosticate. There is general consensus that risk stratification is applicable to newly diagnosed patients; however, some genetic abnormalities characteristic of poor outcome at diagnosis may suggest poor outcome if only detected at the time of relapse. Thus, in good-risk patients, it is necessary to evaluate for high-risk features at relapse. Although detection of any cytogenetic abnormality is considered to suggest higher-risk disease, the specific abnormalities considered as poor risk are cytogenetically detected chromosomal 13 or 13q deletion, t(4; 14) and del17p, and detection by fluorescence in situ hybridization of t(4; 14), t(14; 16), and del17p. Detection of 13q deletion by fluorescence in situ hybridization only, in absence of other abnormalities, is not considered a high-risk feature. High serum beta(2)-microglobulin level and International Staging System stages II and III, incorporating high beta(2)-microglobulin and low albumin, are considered to predict higher risk disease. There was a consensus that the high-risk features will change in the future, with introduction of other new agents or possibly new combinations. (Blood. 2011; 117(18): 4696-4700
Melody and pitch processing in five musical savants with congenital blindness
Abstract. We examined absolute-pitch (AP) and short-term musical memory abilities of five musical savants with congenital blindness, seven musicians, and seven non-musicians with good vision and normal intelligence in two experiments. In the first, short-term memory for musical phrases was tested and the savants and musicians performed statistically indistinguishably, both signifi- cantly outperforming the non-musicians and remembering more material from the C major scale sequences than random trials. In the second experiment, participants learnt associations between four pitches and four objects using a non-verbal paradigm. This experiment approximates to testing AP ability. Low statistical power meant the savants were not statistically better than the musicians, although only the savants scored statistically higher than the non-musicians. The results are evidence for a musical module, separate from general intelligence; they also support the anecdotal reporting of AP in musical savants, which is thought to be necessary for the development of musical-savant skill
Dark Matter Annihilation around Intermediate Mass Black Holes: an update
The formation and evolution of Black Holes inevitably affects the
distribution of dark and baryonic matter in the neighborhood of the Black Hole.
These effects may be particularly relevant around Supermassive and Intermediate
Mass Black Holes (IMBHs), the formation of which can lead to large Dark Matter
overdensities, called {\em spikes} and {\em mini-spikes} respectively. Despite
being larger and more dense, spikes evolve at the very centers of galactic
halos, in regions where numerous dynamical effects tend to destroy them.
Mini-spikes may be more likely to survive, and they have been proposed as
worthwhile targets for indirect Dark Matter searches. We review here the
formation scenarios and the prospects for detection of mini-spikes, and we
present new estimates for the abundances of mini-spikes to illustrate the
sensitivity of such predictions to cosmological parameters and uncertainties
regarding the astrophysics of Black Hole formation at high redshift. We also
connect the IMBHs scenario to the recent measurements of cosmic-ray electron
and positron spectra by the PAMELA, ATIC, H.E.S.S., and Fermi collaborations.Comment: 12 pages, 7 figures. Invited contribution to NJP Focus Issue on "Dark
Matter and Particle Physics
Dark Matter in the MSSM
We have recently examined a large number of points in the parameter space of
the phenomenological MSSM, the 19-dimensional parameter space of the
CP-conserving MSSM with Minimal Flavor Violation. We determined whether each of
these points satisfied existing experimental and theoretical constraints. This
analysis provides insight into general features of the MSSM without reference
to a particular SUSY breaking scenario or any other assumptions at the GUT
scale. This study opens up new possibilities for SUSY phenomenology both in
colliders and in astrophysical experiments. Here we shall discuss the
implications of this analysis relevant to the study of dark matter.Comment: 27 pages, 19 figs; Journal version in NJP issue "Focus on Dark Matter
and Particle Physics". Previous version had 26 pages, 19 figures. Text and
some figures have been update
Scientific Objectives of Einstein Telescope
The advanced interferometer network will herald a new era in observational
astronomy. There is a very strong science case to go beyond the advanced
detector network and build detectors that operate in a frequency range from 1
Hz-10 kHz, with sensitivity a factor ten better in amplitude. Such detectors
will be able to probe a range of topics in nuclear physics, astronomy,
cosmology and fundamental physics, providing insights into many unsolved
problems in these areas.Comment: 18 pages, 4 figures, Plenary talk given at Amaldi Meeting, July 201
The Effect of Human Factor H on Immunogenicity of Meningococcal Native Outer Membrane Vesicle Vaccines with Over-Expressed Factor H Binding Protein
The binding of human complement inhibitors to vaccine antigens in vivo could diminish their immunogenicity. A meningococcal ligand for the complement down-regulator, factor H (fH), is fH-binding protein (fHbp), which is specific for human fH. Vaccines containing recombinant fHbp or native outer membrane vesicles (NOMV) from mutant strains with over-expressed fHbp are in clinical development. In a previous study in transgenic mice, the presence of human fH impaired the immunogenicity of a recombinant fHbp vaccine. In the present study, we prepared two NOMV vaccines from mutant group B strains with over-expressed wild-type fHbp or an R41S mutant fHbp with no detectable fH binding. In wild-type mice in which mouse fH did not bind to fHbp in either vaccine, the NOMV vaccine with wild-type fHbp elicited 2-fold higher serum IgG anti-fHbp titers (Pâ=â0.001) and 4-fold higher complement-mediated bactericidal titers against a PorA-heterologous strain than the NOMV with the mutant fHbp (Pâ=â0.003). By adsorption, the bactericidal antibodies were shown to be directed at fHbp. In transgenic mice in which human fH bound to the wild-type fHbp but not to the R41S fHbp, the NOMV vaccine with the mutant fHbp elicited 5-fold higher serum IgG anti-fHbp titers (Pâ=â0.002), and 19-fold higher bactericidal titers than the NOMV vaccine with wild-type fHbp (Pâ=â0.001). Thus, in mice that differed only by the presence of human fH, the respective results with the two vaccines were opposite. The enhanced bactericidal activity elicited by the mutant fHbp vaccine in the presence of human fH far outweighed the loss of immunogenicity of the mutant protein in wild-type animals. Engineering fHbp not to bind to its cognate complement inhibitor, therefore, may increase vaccine immunogenicity in humans
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