184 research outputs found
Selective blockade of Interferon-α and -β reveals their non-redundant functions in a mouse model of West Nile virus infection
Although type I interferons (IFNs) were first described almost 60 years ago, the ability to monitor and modulate the functional activities of the individual IFN subtypes that comprise this family has been hindered by a lack of reagents. The major type I IFNs, IFN-β and the multiple subtypes of IFN-α, are expressed widely and induce their effects on cells by interacting with a shared heterodimeric receptor (IFNAR). In the mouse, the physiologic actions of IFN-α and IFN-β have been defined using polyclonal anti-type I IFN sera, by targeting IFNAR using monoclonal antibodies or knockout mice, or using Ifnb-/- mice. However, the corresponding analysis of IFN-α has been difficult because of its polygenic nature. Herein, we describe two monoclonal antibodies (mAbs) that differentially neutralize murine IFN-β or multiple subtypes of murine IFN-α. Using these mAbs, we distinguish specific contributions of IFN-β versus IFN-α in restricting viral pathogenesis and identify IFN-α as the key mediator of the antiviral response in mice infected with West Nile virus. This study thus suggests the utility of these new reagents in dissecting the antiviral and immunomodulatory roles of IFN-β versus IFN-α in murine models of infection, immunity, and autoimmunity
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Fiscal year 1997 Memorandum of Understanding for the TWRS characterization project
During fiscal year 1997, the level of success achieved by the Tank Waste Remediation System (TWRS) shall be determined by specific performance measures. These measures take the form of significant deliverables, one of which is the completion of Tank Characterization Reports (TCRs). In order to achieve success regarding the TCR performance deliverable, multiple organizations across TWRS must work together. Therefore, the requirements and expectations needed from each of these TWRS organizations were examined in order to gain an understanding of the performance necessary from each organization to achieve the end deliverable. This memorandum of understanding (MOU) documents the results of this review and establishes the performance criteria by which TWRS will assess its progress and success. These criteria have been determined based upon a TWRS Characterization Project budget of $56.8 million for fiscal year 1997; if this budget is changed or the currently identified workscope is modified, this MOU will need to be revised accordingly. This MOU is subdivided into six sections, where sections three through six each identify individual interfaces between TWRS organizations. The specific performance criteria related to each TWRS organizational interface are then delineated in the section, along with any additional goals or issues pertaining to that interface
The IMF in Starbursts
The history of the IMF in starburst regions is reviewed. The IMFs are no
longer believed to be top-heavy, although some superstar clusters, whether in
starburst regions or not, could be. General observations of the IMF are
discussed to put the starburst results in perspective. Observed IMF variations
seem to suggest that the IMF varies a little with environment in the sense that
denser and more massive clusters produce more massive stars, and perhaps more
brown dwarfs too, compared to intermediate mass stars.Comment: 8 pages, to be published in ``Starbursts: from 30 Doradus to Lyman
Break Galaxies,'' held at Institute of Astronomy, Cambridge University, UK,
September 6-10, 2004. Kluwer Academic Publishers, edited by Richard de Grijs
and Rosa M. Gonzalez Delgad
The Nucleon's Virtual Meson Cloud and Deep Inelastic Lepton Scattering
We address the question whether the nucleon's antiquark sea can be attributed
entirely to its virtual meson cloud and, in essence, whether there exists a
smooth transition between hadronic and quark-gluon degrees of freedom. We take
into account contributions from and mesons and compare with the
nucleon's antiquark distributions which serve as a non-perturbative input to
the QCD evolution equations. We elucidate the different behavior in the flavor
singlet and non-singlet channels and study the dependence of our results on the
scale . The meson-nucleon cut-offs that we determine give not only an
indication on the size of the region within which quarks are confined in a
nucleon, but we find that the scale of these form factors is closely related to
the four-momentum transfer, , where gluons are resolved by a high energy
probe, and that large meson loop momenta, GeV,
contribute significantly to the sea quark distributions. While the agreement of
our calculations with data-based parametrizations is satisfactory and scale
independent for the flavor breaking share of the nucleon's antiquark sea, the
flavor singlet component is quite poorly described. This hints the importance
of gluon degrees of freedom.Comment: 34 pages, RevTeX, 6 figures optionally included using epsfig.st
Cluster Density and the IMF
Observed variations in the IMF are reviewed with an emphasis on environmental
density. The remote field IMF studied in the LMC by several authors is clearly
steeper than most cluster IMFs, which have slopes close to the Salpeter value.
Local field regions of star formation, like Taurus, may have relatively steep
IMFs too. Very dense and massive clusters, like super star clusters, could have
flatter IMFs, or inner-truncated IMFs. We propose that these variations are the
result of three distinct processes during star formation that affect the mass
function in different ways depending on mass range. At solar to intermediate
stellar masses, gas processes involving thermal pressure and supersonic
turbulence determine the basic scale for stellar mass, starting with the
observed pre-stellar condensations, and they define the mass function from
several tenths to several solar masses. Brown dwarfs require extraordinarily
high pressures for fragmentation from the gas, and presumably form inside the
pre-stellar condensations during mutual collisions, secondary fragmentations,
or in disks. High mass stars form in excess of the numbers expected from pure
turbulent fragmentation as pre-stellar condensations coalesce and accrete with
an enhanced gravitational cross section. Variations in the interaction rate,
interaction strength, and accretion rate among the primary fragments formed by
turbulence lead to variations in the relative proportions of brown dwarfs,
solar to intermediate mass stars, and high mass stars.Comment: 14 pages, 3 figures, to be published in ``IMF@50: A Fest-Colloquium
in honor of Edwin E. Salpeter,'' held at Abbazia di Spineto, Siena, Italy,
May 16-20, 2004. Kluwer Academic Publishers; edited by E. Corbelli, F. Palla,
and H. Zinnecke
Strategies for Controlled Placement of Nanoscale Building Blocks
The capability of placing individual nanoscale building blocks on exact substrate locations in a controlled manner is one of the key requirements to realize future electronic, optical, and magnetic devices and sensors that are composed of such blocks. This article reviews some important advances in the strategies for controlled placement of nanoscale building blocks. In particular, we will overview template assisted placement that utilizes physical, molecular, or electrostatic templates, DNA-programmed assembly, placement using dielectrophoresis, approaches for non-close-packed assembly of spherical particles, and recent development of focused placement schemes including electrostatic funneling, focused placement via molecular gradient patterns, electrodynamic focusing of charged aerosols, and others
Erratum: "A Gravitational-wave Measurement of the Hubble Constant Following the Second Observing Run of Advanced LIGO and Virgo" (2021, ApJ, 909, 218)
[no abstract available
All-sky search for long-duration gravitational wave transients with initial LIGO
We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society
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