640 research outputs found
Relating the Lorentzian and exponential: Fermi's approximation,the Fourier transform and causality
The Fourier transform is often used to connect the Lorentzian energy
distribution for resonance scattering to the exponential time dependence for
decaying states. However, to apply the Fourier transform, one has to bend the
rules of standard quantum mechanics; the Lorentzian energy distribution must be
extended to the full real axis instead of being bounded from
below (``Fermi's approximation''). Then the Fourier transform
of the extended Lorentzian becomes the exponential, but only for times , a time asymmetry which is in conflict with the unitary group time evolution
of standard quantum mechanics. Extending the Fourier transform from
distributions to generalized vectors, we are led to Gamow kets, which possess a
Lorentzian energy distribution with and have exponential
time evolution for only. This leads to probability predictions
that do not violate causality.Comment: 23 pages, no figures, accepted by Phys. Rev.
Compositional tuning of ferromagnetism in Ga1-xMnxP
We report the magnetic and transport properties of Ga1-xMnxP synthesized via
ion implantation followed by pulsed laser melting over a range of x, namely
0.018 to 0.042. Like Ga1-xMnxAs, Ga1-xMnxP displays a monotonic increase of the
ferromagnetic Curie temperature with x associated with the hole-mediated
ferromagnetic phase while thermal annealing above 300 C leads to a quenching of
ferromagnetism that is accompanied by a reduction of the substitutional
fraction of Mn. However, contrary to observations in Ga1-xMnxAs, Ga1-xMnxP is
non-metallic over the entire composition range. At the lower temperatures over
which the films are ferromagnetic, hole transport occurs via hopping conduction
in a Mn-derived band; at higher temperatures it arises from holes in the
valence band which are thermally excited across an energy gap that shrinks with
x.Comment: To be published in Solid State Communication
Applicability and Cost Implications for Proprotein Convertase Subtilisin/Kexin Type 9 Inhibitors Based on the ODYSSEY Outcomes Trial: Insights From the Department of Veterans Affairs
In the recently presented ODYSSEY Outcomes: Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab trial, alirocumab use in patients with acute coronary syndrome (ACS) and low-density lipoprotein cholesterol (LDL-C) â„70 mg/dL (or nonâhigh-density lipoprotein cholesterol â„100 mg/dL or apolipoprotein B â„80 mg/dL) resulted in a 15% relative (1.6% absolute) reduction in the risk of major adverse cardiovascular events. We evaluated what proportion of patients in the VA Health Care System would qualify for alirocumab on the basis of ODYSSEY Outcomes criteria, how they are currently treated with LDL-Câlowering medications, and the cost implications if other evidence-based medications were used first before a proprotein convertase subtilisin/kexin type 9 inhibitor was considered
Very High-Risk ASCVD and Eligibility for Nonstatin Therapies Based on the 2018 AHA/ACC Cholesterol Guidelines
The 2018 American Heart Association/American College of Cardiology Multisociety Cholesterol Guidelines recommend risk stratification among patients with atherosclerotic cardiovascular disease (ASCVD) to identify âvery high-risk ASCVD patients.â These patients have characteristics associated with a higher risk of recurrent ASCVD events; consequently, they derive a higher net absolute benefit from addition of ezetimibe and/or a proprotein convertase subtilisin/kexin type 9 inhibitor (PCSK9i) to statin therapy. From a clinical and payerâs perspective, we assessed the proportion of patients with ASCVD who will qualify as very high-risk based on the guideline criteria, their current lipid management, and how this will change with maximizing statin therapy and stepwise use of ezetimibe before consideration for a PCSK9i, as recommended by the 2018 cholesterol guideline
A randomized, phase II study of sequential belimumab and rituximab in primary Sjögren's syndrome
BACKGROUND: Primary Sjögrenâs syndrome (pSS) is characterized by B cell hyperactivity and elevated B-lymphocyte stimulator (BLyS). Anti-BLyS treatment (e.g., belimumab) increases peripheral memory B cells; decreases naive, activated, and plasma B cell subsets; and increases stringency on B cell selection during reconstitution. Anti-CD20 therapeutics (e.g., rituximab) bind and deplete CD20-expressing B cells in circulation but are less effective in depleting tissue-resident CD20(+) B cells. Combined, these 2 mechanisms may achieve synergistic effects. METHODS: This 68-week, phase II, double-blind study (GSK study 201842) randomized 86 adult patients with active pSS to 1 of 4 arms: placebo, s.c. belimumab, i.v. rituximab, or sequential belimumab + rituximab. RESULTS: Overall, 60 patients completed treatment and follow-up until week 68. The incidence of adverse events (AEs) and drug-related AEs was similar across groups. Infections/infestations were the most common AEs, and no serious infections of special interest occurred. Near-complete depletion of minor salivary gland CD20(+) B cells and a greater and more sustained depletion of peripheral CD19(+) B cells were observed with belimumab + rituximab versus monotherapies. With belimumab + rituximab, reconstitution of peripheral B cells occurred, but it was delayed compared with rituximab. At week 68, mean (± standard error) total EULAR Sjögrenâs syndrome disease activity index scores decreased from 11.0 (1.17) at baseline to 5.0 (1.27) for belimumab + rituximab and 10.4 (1.36) to 8.6 (1.57) for placebo. CONCLUSION: The safety profile of belimumab + rituximab in pSS was consistent with the monotherapies. Belimumab + rituximab induced enhanced salivary gland B cell depletion relative to the monotherapies, potentially leading to improved clinical outcomes. TRIAL REGISTRATION: ClinicalTrials.gov NCT02631538. FUNDING: Funding was provided by GSK
Accretion, Outflows, and Winds of Magnetized Stars
Many types of stars have strong magnetic fields that can dynamically
influence the flow of circumstellar matter. In stars with accretion disks, the
stellar magnetic field can truncate the inner disk and determine the paths that
matter can take to flow onto the star. These paths are different in stars with
different magnetospheres and periods of rotation. External field lines of the
magnetosphere may inflate and produce favorable conditions for outflows from
the disk-magnetosphere boundary. Outflows can be particularly strong in the
propeller regime, wherein a star rotates more rapidly than the inner disk.
Outflows may also form at the disk-magnetosphere boundary of slowly rotating
stars, if the magnetosphere is compressed by the accreting matter. In isolated,
strongly magnetized stars, the magnetic field can influence formation and/or
propagation of stellar wind outflows. Winds from low-mass, solar-type stars may
be either thermally or magnetically driven, while winds from massive, luminous
O and B type stars are radiatively driven. In all of these cases, the magnetic
field influences matter flow from the stars and determines many observational
properties. In this chapter we review recent studies of accretion, outflows,
and winds of magnetized stars with a focus on three main topics: (1) accretion
onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and
(3) winds from isolated massive magnetized stars. We show results obtained from
global magnetohydrodynamic simulations and, in a number of cases compare global
simulations with observations.Comment: 60 pages, 44 figure
Bringing community perceptions into sustainable urban drainage systems:The experience of Extremadura, Spain
The Structure of a Rigorously Conserved RNA Element within the SARS Virus Genome
We have solved the three-dimensional crystal structure of the stem-loop II motif (s2m) RNA element of the SARS virus genome to 2.7-Ă
resolution. SARS and related coronaviruses and astroviruses all possess a motif at the 3âČ end of their RNA genomes, called the s2m, whose pathogenic importance is inferred from its rigorous sequence conservation in an otherwise rapidly mutable RNA genome. We find that this extreme conservation is clearly explained by the requirement to form a highly structured RNA whose unique tertiary structure includes a sharp 90° kink of the helix axis and several novel longer-range tertiary interactions. The tertiary base interactions create a tunnel that runs perpendicular to the main helical axis whose interior is negatively charged and binds two magnesium ions. These unusual features likely form interaction surfaces with conserved host cell components or other reactive sites required for virus function. Based on its conservation in viral pathogen genomes and its absence in the human genome, we suggest that these unusual structural features in the s2m RNA element are attractive targets for the design of anti-viral therapeutic agents. Structural genomics has sought to deduce protein function based on three-dimensional homology. Here we have extended this approach to RNA by proposing potential functions for a rigorously conserved set of RNA tertiary structural interactions that occur within the SARS RNA genome itself. Based on tertiary structural comparisons, we propose the s2m RNA binds one or more proteins possessing an oligomer-binding-like fold, and we suggest a possible mechanism for SARS viral RNA hijacking of host protein synthesis, both based upon observed s2m RNA macromolecular mimicry of a relevant ribosomal RNA fold
Measurement of the CP-violating phase \phi s in Bs->J/\psi\pi+\pi- decays
Measurement of the mixing-induced CP-violating phase phi_s in Bs decays is of
prime importance in probing new physics. Here 7421 +/- 105 signal events from
the dominantly CP-odd final state J/\psi pi+ pi- are selected in 1/fb of pp
collision data collected at sqrt{s} = 7 TeV with the LHCb detector. A
time-dependent fit to the data yields a value of
phi_s=-0.019^{+0.173+0.004}_{-0.174-0.003} rad, consistent with the Standard
Model expectation. No evidence of direct CP violation is found.Comment: 15 pages, 10 figures; minor revisions on May 23, 201
Measurement of the branching fraction
The branching fraction is measured in a data sample
corresponding to 0.41 of integrated luminosity collected with the LHCb
detector at the LHC. This channel is sensitive to the penguin contributions
affecting the sin2 measurement from The
time-integrated branching fraction is measured to be . This is the most precise measurement to
date
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