6,794 research outputs found
An Annotated Catalogue of the Recent Mammals of Iowa
In forming a collection of the fauna of Iowa for the museum of the Historical Department of Iowa, it was early seen that there was no published lists, and but very meager and scattered records of the mammals of the state. It is this condition of affairs which has prompted the compiling of such at this time
U94, the Human Herpesvirus 6 Homolog of the Parvovirus Nonstructural Gene, Is Highly Conserved among Isolates and Is Expressed at Low mRNA Levels as a Spliced Transcript
AbstractHuman herpesvirus 6 variants A and B (HHV-6A and HHV-6B, respectively) encode homologs (U94) of the parvovirus nonstructural gene, ns1 or rep. Here we describe the HHV-6B homolog and analyze its genetic heterogeneity and transcription. U94 nucleotide and amino acid sequences differ by approximately 3.5% and 2.5%, respectively, between HHV-6A and HHV-6B. Among a collection of 17 clinically and geographically disparate HHV-6 isolates, intravariant nucleotide and amino acid sequence divergence was less than 0.6% and 0.2%, respectively; all 13 HHV-6B isolates had identical amino acid sequences. The U94 transcript is spliced to remove a 2.6-kb intron and is expressed at very low levels relative to other HHV-6B genes, reaching approximately 10 copies per cell 3 days after infection. The mRNA has several small AUG-initiated open reading frames upstream of the U94 open reading frame, a hallmark of proteins expressed at low levels. Consistent with this, the U94-encoded protein was immunologically undetectable in HHV-6B-infected cells. The high degree of sequence conservation suggests that the gene function is nearly intolerant of sequence variation. The low abundance of U94 transcripts and the presence of encoded inefficient translation initiation suggest that the U94 protein may be required only in small amounts during infection
Shuttle Gaseous Hydrogen Venting Risk from Flow Control Valve Failure
This paper describes a series of studies to assess the potential risk associated with the failure of one of three gaseous hydrogen flow control valves in the orbiter's main propulsion system during the launch of Shuttle Endeavour (STS-126) in November 2008. The studies focused on critical issues associated with the possibility of combustion resulting from release of gaseous hydrogen from the external tank into the atmosphere during assent. The Shuttle Program currently assumes hydrogen venting from the external tank will result in a critical failure. The current effort was conducted to increase understanding of the risk associated with venting hydrogen given the flow control valve failure scenarios being considered in the Integrated In-Flight Anomaly Investigation being conducted by NASA
Fine Mapping Major Histocompatibility Complex Associations in Psoriasis and Its Clinical Subtypes
Psoriasis vulgaris (PsV) risk is strongly associated with variation within the major histocompatibility complex (MHC) region, but its genetic architecture has yet to be fully elucidated. Here, we conducted a large-scale fine-mapping study of PsV risk in the MHC region in 9,247 PsV-affected individuals and 13,589 controls of European descent by imputing class I and II human leukocyte antigen (HLA) genes from SNP genotype data. In addition, we imputed sequence variants for MICA, an MHC HLA-like gene that has been associated with PsV, to evaluate association at that locus as well. We observed that HLA-C*06:02 demonstrated the lowest p value for overall PsV risk (p = 1.7 x 10(-364)). Stepwise analysis revealed multiple HLA-C*06:02-independent risk variants in both class I and class II HLA genes for PsV susceptibility (HLA-C*12:03, HLA-B amino acid positions 67 and 9, HLA-A amino acid position 95, and HLA-DQ alpha 1 amino acid position 53; p \u3c 5.0 x 10(-8)), but no apparent risk conferred by MICA. We further evaluated risk of two major clinical subtypes of PsV, psoriatic arthritis (PsA; n = 3,038) and cutaneous psoriasis (PsC; n = 3,098). We found that risk heterogeneity between PsA and PsC might be driven by HLA-B amino acid position 45 (P-omnibus = 2.2 x 10(-11)), indicating that different genetic factors underlie the overall risk of PsV and the risk of specific PsV subphenotypes. Our study illustrates the value of high-resolution HLA and MICA imputation for fine mapping causal variants in the MHC
Measurement of direct photon production at Tevatron fixed target energies
Measurements of the production of high transverse momentum direct photons by
a 515 GeV/c piminus beam and 530 and 800 GeV/c proton beams in interactions
with beryllium and hydrogen targets are presented. The data span the kinematic
ranges of 3.5 < p_T < 12 GeV/c in transverse momentum and 1.5 units in
rapidity. The inclusive direct-photon cross sections are compared with
next-to-leading-order perturbative QCD calculations and expectations based on a
phenomenological parton-k_T model.Comment: RevTeX4, 23 pages, 32 figures, submitted to Phys. Rev.
Measurement of the Strong Coupling Constant from Inclusive Jet Production at the Tevatron Collider
We report a measurement of the strong coupling constant, ,
extracted from inclusive jet production in collisions at
1800 GeV. The QCD prediction for the evolution of with
jet transverse energy is tested over the range 40<<450 GeV using
for the renormalization scale. The data show good agreement with QCD in
the region below 250 GeV. In the text we discuss the data-theory comparison in
the region from 250 to 450 GeV. The value of at the mass of the
boson averaged over the range 40<<250 GeV is found to be
. The associated theoretical uncertainties are mainly due to the choice
of renormalization scale (^{+6%}_{-4%}) and input parton distribution
functions (5%).Comment: 7 pages, 3 figures, using RevTeX. Submitted to Physical Review
Letter
Evidence for Parton kT Effects in High pT Particle Production
Inclusive pizero and direct-photon cross sections in the kinematic range 3.5
< pT < 12 GeV/c with central rapidities are presented for 530 and 800 GeV/c
proton beams and a 515 GeV/c pi- beam incident on beryllium targets. Current
Next-to-Leading-Order perturbative QCD calculations fail to adequately describe
the data for conventional choices of scales. Kinematic distributions from these
hard scattering events provide evidence that the interacting partons carry
significant initial-state parton transverse momentum (kT). Incorporating these
kT effects phenomenologically greatly improves the agreement between
calculations and the measured cross sections.Comment: 11 pages including 6 pages of figures with caption
Search for Kaluza-Klein Graviton Emission in Collisions at TeV using the Missing Energy Signature
We report on a search for direct Kaluza-Klein graviton production in a data
sample of 84 of \ppb collisions at = 1.8 TeV, recorded
by the Collider Detector at Fermilab. We investigate the final state of large
missing transverse energy and one or two high energy jets. We compare the data
with the predictions from a -dimensional Kaluza-Klein scenario in which
gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for
=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71
TeV, respectively.Comment: Submitted to PRL, 7 pages 4 figures/Revision includes 5 figure
Measurement of the average time-integrated mixing probability of b-flavored hadrons produced at the Tevatron
We have measured the number of like-sign (LS) and opposite-sign (OS) lepton
pairs arising from double semileptonic decays of and -hadrons,
pair-produced at the Fermilab Tevatron collider. The data samples were
collected with the Collider Detector at Fermilab (CDF) during the 1992-1995
collider run by triggering on the existence of and candidates
in an event. The observed ratio of LS to OS dileptons leads to a measurement of
the average time-integrated mixing probability of all produced -flavored
hadrons which decay weakly, (stat.)
(syst.), that is significantly larger than the world average .Comment: 47 pages, 10 figures, 15 tables Submitted to Phys. Rev.
- …