368 research outputs found
Residential mobility and local housing-market differences
The authors extend previous literature on variations in mobility rates across local housing markets by examining the linkage of mobility rates at the household level to the structure of local housing markets. The results suggest that residential mobility rates differ widely across local housing markets, substantiating the view that residential relocation is intimately intertwined with conditions at the local level. Local housing-market conditions also have different effects on mobility rates for renters and owner-occupiers. The results suggest that variation in residential mobility rates across housing markets can be in part explained by level of urbanization, the tenure structure, the degree of government intervention, and the size of the housing market. Remarkably, these differences in local housing markets cannot be seen to be related to housing-market features only. The results suggest that these differences can also be attributed to the behavior or attitude of households with respect to housing
Where does Cosmological Perturbation Theory Break Down?
We apply the effective field theory approach to the coupled metric-inflaton
system, in order to investigate the impact of higher dimension operators on the
spectrum of scalar and tensor perturbations in the short-wavelength regime. In
both cases, effective corrections at tree-level become important when the
Hubble parameter is of the order of the Planck mass, or when the physical wave
number of a cosmological perturbation mode approaches the square of the Planck
mass divided by the Hubble constant. Thus, the cut-off length below which
conventional cosmological perturbation theory does not apply is likely to be
much smaller than the Planck length. This has implications for the
observability of "trans-Planckian" effects in the spectrum of primordial
perturbations.Comment: 25 pages, uses FeynM
Decoupling in an expanding universe: boundary RG-flow affects initial conditions for inflation
We study decoupling in FRW spacetimes, emphasizing a Lagrangian description
throughout. To account for the vacuum choice ambiguity in cosmological
settings, we introduce an arbitrary boundary action representing the initial
conditions. RG flow in these spacetimes naturally affects the boundary
interactions. As a consequence the boundary conditions are sensitive to
high-energy physics through irrelevant terms in the boundary action. Using
scalar field theory as an example, we derive the leading dimension four
irrelevant boundary operators. We discuss how the known vacuum choices, e.g.
the Bunch-Davies vacuum, appear in the Lagrangian description and square with
decoupling. For all choices of boundary conditions encoded by relevant boundary
operators, of which the known ones are a subset, backreaction is under control.
All, moreover, will generically feel the influence of high-energy physics
through irrelevant (dimension four) boundary corrections. Having established a
coherent effective field theory framework including the vacuum choice
ambiguity, we derive an explicit expression for the power spectrum of
inflationary density perturbations including the leading high energy
corrections. In accordance with the dimensionality of the leading irrelevant
operators, the effect of high energy physics is linearly proportional to the
Hubble radius H and the scale of new physics L= 1/M.Comment: LaTeX plus axodraw figures. v2: minor corrections; refs added. JHEP
style: 34 pages + 18 pages appendi
Reduced Heart Failure and Mortality in Patients Receiving Statin Therapy Before Initial Acute Coronary Syndrome
Background: There is uncertainty regarding the impact of statins on the risk of atherosclerotic cardiovascular disease (ASCVD) and its major complication, acute heart failure (AHF). Objectives: The aim of this study was to investigate whether previous statin therapy translates into lower AHF events and improved survival from AHF among patients presenting with an acute coronary syndrome (ACS) as a first manifestation of ASCVD. Methods: Data were drawn from the International Survey of Acute Coronary Syndromes Archives. The study participants consisted of 14,542 Caucasian patients presenting with ACS without previous ASCVD events. Statin users before the index event were compared with nonusers by using inverse probability weighting models. Estimates were compared by test of interaction on the log scale. Main outcome measures were the incidence of AHF according to Killip class and the rate of 30-day all-cause mortality in patients presenting with AHF. Results: Previous statin therapy was associated with a significantly decreased rate of AHF on admission (4.3% absolute risk reduction; risk ratio [RR]: 0.72; 95% CI: 0.62-0.83) regardless of younger (40-75 years) or older age (interaction P = 0.27) and sex (interaction P = 0.22). Moreover, previous statin therapy predicted a lower risk of 30-day mortality in the subset of patients presenting with AHF on admission (5.2 % absolute risk reduction; RR: 0.71; 95% CI: 0.50-0.99). Conclusions: Among adults presenting with ACS as a first manifestation of ASCVD, previous statin therapy is associated with a reduced risk of AHF and improved survival from AHF. (International Survey of Acute Coronary Syndromes [ISACS] Archives; NCT04008173
Light-like noncommutativity and duality from open strings/branes
In this paper we perform some non-trivial tests for the recently obtained
open membrane/D-brane metrics and `generalized' noncommutativity parameters
using Dp/NS5/M5-branes which have been deformed by light-like fields. The
results obtained give further evidence that these open membrane/D-brane metrics
and `generalized' noncommutativity parameters are correct. Further, we use the
open brane data and supergravity duals to obtain more information about
non-gravitational theories with light-like noncommutativity, or `generalized'
light-like noncommutativity. In particular, we investigate various duality
relations (strong coupling limits). In the light-like case we also comment on
the relation between open membrane data (open membrane metric etc.) in six
dimensions and open string data in five dimensions. Finally, we investigate the
strong coupling limit (high energy limit) of five dimensional NCYM with
\Theta^{12}=\Theta^{34}. In particular, we find that this NCYM theory can be UV
completed by a DLCQ compactification of M-theory.Comment: 24 pages, Latex. v2:Comments and references added. v3:Version
published in JHE
Small-Molecule Inhibitors of Dengue-Virus Entry
Flavivirus envelope protein (E) mediates membrane fusion and viral entry from endosomes. A low-pH induced, dimer-to-trimer rearrangement and reconfiguration of the membrane-proximal “stem" of the E ectodomain draw together the viral and cellular membranes. We found stem-derived peptides from dengue virus (DV) bind stem-less E trimer and mimic the stem-reconfiguration step in the fusion pathway. We adapted this experiment as a high-throughput screen for small molecules that block peptide binding and thus may inhibit viral entry. A compound identified in this screen, 1662G07, and a number of its analogs reversibly inhibit DV infectivity. They do so by binding the prefusion, dimeric E on the virion surface, before adsorption to a cell. They also block viral fusion with liposomes. Structure-activity relationship studies have led to analogs with submicromolar IC90s against DV2, and certain analogs are active against DV serotypes 1,2, and 4. The compounds do not inhibit the closely related Kunjin virus. We propose that they bind in a previously identified, E-protein pocket, exposed on the virion surface and although this pocket is closed in the postfusion trimer, its mouth is fully accessible. Examination of the E-trimer coordinates (PDB 1OK8) shows that conformational fluctuations around the hinge could open the pocket without dissociating the trimer or otherwise generating molecular collisions. We propose that compounds such as 1662G07 trap the sE trimer in a “pocket-open" state, which has lost affinity for the stem peptide and cannot support the final “zipping up" of the stem
De Sitter Holography and the Cosmic Microwave Background
We interpret cosmological evolution holographically as a renormalisation
group flow in a dual Euclidean field theory, as suggested by the conjectured
dS/CFT correspondence. Inflation is described by perturbing around the
infra-red fixed point of the dual field theory. The spectrum of the cosmic
microwave background radiation is determined in terms of scaling violations in
the field theory. The dark energy allows similar, albeit less predictive,
considerations. We discuss the cosmological fine-tuning problems from the
holographic perspective.Comment: 17 pages, 2 figures, uses JHEP style files; corrected and added
reference
Relativistic effects and two-body currents in using out-of-plane detection
Measurements of the reaction were performed
using an 800-MeV polarized electron beam at the MIT-Bates Linear Accelerator
and with the out-of-plane magnetic spectrometers (OOPS). The
longitudinal-transverse, and , and the
transverse-transverse, , interference responses at a missing momentum
of 210 MeV/c were simultaneously extracted in the dip region at Q=0.15
(GeV/c). On comparison to models of deuteron electrodisintegration, the
data clearly reveal strong effects of relativity and final-state interactions,
and the importance of the two-body meson-exchange currents and isobar
configurations. We demonstrate that these effects can be disentangled and
studied by extracting the interference response functions using the novel
out-of-plane technique.Comment: 4 pages, 4 figures, and submitted to PRL for publicatio
Observational Signatures and Non-Gaussianities of General Single Field Inflation
We perform a general study of primordial scalar non-Gaussianities in single
field inflationary models in Einstein gravity. We consider models where the
inflaton Lagrangian is an arbitrary function of the scalar field and its first
derivative, and the sound speed is arbitrary. We find that under reasonable
assumptions, the non-Gaussianity is completely determined by 5 parameters. In
special limits of the parameter space, one finds distinctive ``shapes'' of the
non-Gaussianity. In models with a small sound speed, several of these shapes
would become potentially observable in the near future. Different limits of our
formulae recover various previously known results.Comment: 53 pages, 5 figures; v3, minor revision, JCAP version; v4, numerical
coefficients corrected in Appendix B, discussion on consistency condition
revise
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