335 research outputs found
Predictions for neutrino structure functions.
The first measurements of xF3 are higher than current theoretical predictions. We investigate the sensitivity of these
theoretical predictions upon a variety of factors including: renormalization scheme and scale, quark mass effects, higher twist,
isospin violation, and PDF uncertainties
De novo 1q21.3q22 duplication revaluation in a “cold” complex neuropsychiatric case with syndromic intellectual disability
Syndromic intellectual disability often obtains a genetic diagnosis due to the combination of first and next generation sequencing techniques, although their interpretation may require revaluation over the years. Here we report on a composite neuropsychiatric case whose phenotype includes moderate intellectual disability, spastic paraparesis, movement disorder, and bipolar disorder, harboring a 1.802 Mb de novo 1q21.3q22 duplication. The role of this duplication has been reconsidered in the light of negativity of many other genetic exams, and of the possible pathogenic role of many genes included in this duplication, potentially configuring a contiguous gene-duplication syndrome
Heavy Quark Production and PDF's Subgroup Report
We present a status report of a variety of projects related to heavy quark
production and parton distributions for the Tevatron Run II.Comment: Latex. 8 pages, 7 eps figures. Contribution to the Physics at Run II
Workshops: QCD and Weak Boson Physic
Novel insights into the transport mechanism of the human amino acid transporter LAT1 (SLC7A5) : probing critical residues for substrate translocation
BACKGROUND:
LAT1 (SLC7A5) is the transport competent unit of the heterodimer formed with the glycoprotein CD98 (SLC3A2). It catalyzes antiport of His and some neutral amino acids such as Ile, Leu, Val, Cys, Met, Gln and Phe thus being involved in amino acid metabolism. Interestingly, LAT1 is over-expressed in many human cancers that are characterized by increased demand of amino acids. Therefore LAT1 was recently acknowledged as a novel target for cancer therapy. However, knowledge on molecular mechanism of LAT1 transport is still scarce.
METHODS:
Combined approaches of bioinformatics, site-directed mutagenesis, chemical modification, and transport assay in proteoliposomes, have been adopted to unravel dark sides of human LAT1 structure/function relationships.
RESULTS:
It has been demonstrated that residues F252, S342, C335 are crucial for substrate recognition and C407 plays a minor role. C335 and C407 cannot be targeted by SH reagents. The transporter has a preferential dimeric structure and catalyzes an antiport reaction which follows a simultaneous random mechanism.
CONCLUSIONS:
Critical residues of the substrate binding site of LAT1 have been probed. This site is not freely accessible by molecules other than substrate. Similarly to LeuT, K+ has some regulatory properties on LAT1.
GENERAL SIGNIFICANCE:
The collected data represent a solid basis for deciphering molecular mechanism underlying LAT1 function
Parton Distributions Working Group
The main focus of this working group was to investigate the different issues
associated with the development of quantitative tools to estimate parton
distribution functions uncertainties. In the conclusion, we introduce a
"Manifesto" that describes an optimal method for reporting data.Comment: Report of the Parton Distributions Working Group of the 'QCD and Weak
Boson Physics workshop in preparation for Run II at the Fermilab Tevatron'.
Co-Conveners: L. de Barbaro, S.A. Keller, S. Kuhlmann, H. Schellman, and
W.-K. Tun
Heavy Quark Parton Distributions: Mass-Dependent or Mass-Independent Evolution?
In a consistently formulated pQCD framework incorporating non-zero mass heavy
quark partons, there is still the freedom to define parton distributions
obeying either mass-independent or mass-dependent evolution equations, contrary
to statements made in a recent paper by MRRS. With properly matched hard
cross-sections, different choices merely correspond to different factorization
schemes, and they yield the same physical cross-sections. We demonstrate this
principle in a concrete order \alpha_s calculation of the DIS charm structure
function. We also examine the proper matching between parton definitions and
subtractions in the hard cross-section near threshold where the calculation is
particularly sensitive to mass effects of the heavy quark. The results obtained
from the general-mass formalism are quite stable against different choices of
scale and exhibit a smooth transition in the threshold region (using either
mass-independent or mass-dependent evolution), in contrast to results of
another recently proposed scheme.Comment: 6 pages, LaTeX, 4 PostScript figures, uses epsf.sty and aipproc.sty;
Contribution to DIS97 Workshop, 14-18 April, Chicago, IL, US
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