215 research outputs found
Pion and Kaon Production in and Collisions at Next-to-Leading Order
We present new sets of fragmentation functions for charged pions and kaons,
both at leading and next-to-leading order. They are fitted to data on inclusive
charged-hadron production in annihilation taken by TPC at PEP (~GeV) and to similar data by ALEPH at LEP, who discriminated between
events with charm, bottom, and light- flavour fragmentation in their
charged-hadron sample. We treat all partons independently and to properly
incorporate the charm and bottom thresholds. Due to the sizeable energy gap
between PEP and LEP, we are sensitive to the scaling violation in the
fragmentation process, which allows us to extract a value for the asymptotic
scale parameter of QCD, . Recent data on inclusive charged-hadron
production in tagged three-jet events by OPAL and similar data for longitudinal
electron polarization by ALEPH allow us to pin down the gluon fragmentation
functions. Our new fragmentation functions lead to an excellent description of
a multitude of other data on inclusive charged-hadron production,
ranging from ~GeV to LEP energy. In addition, they agree nicely
with the transverse-momentum spectra of single charged hadrons measured by H1
and ZEUS in photoproduction at the collider HERA, which represents a
nontrivial check of the factorization theorem of the QCD-improved parton model.Comment: 22 pages, latex, 13 compressed ps figures in separate fil
Generalizations of Gronwall-Bihari Inequalities on Time Scales
We establish some nonlinear integral inequalities for functions defined on a
time scale. The results extend some previous Gronwall and Bihari type
inequalities on time scales. Some examples of time scales for which our results
can be applied are provided. An application to the qualitative analysis of a
nonlinear dynamic equation is discussed.Comment: This is a preprint of an article accepted (16/May/2008) for
publication in the "Journal of Difference Equations and Applications"; J.
Difference Equ. Appl. is available online at http://www.informaworld.co
Next-to-Leading Order Fragmentation Functions for Pions and Kaons
We present new sets of fragmentation functions for charged pions and kaons,
both at leading and next-to-leading order. They are fitted to TPC data taken at
energy ~GeV and describe excellently a wealth of other
data on charged-hadron production, ranging from ~GeV way up to
LEP~1 energy. They also agree with data on the production of neutral pions and
kaons, if one makes the natural assumption that the respective fragmentation
functions are related to the charged counterparts by SU(2) symmetry. We also
list simple parameterizations of the and dependence of our results,
which may be implemented conveniently in applications.Comment: 22 p. + 12 figures (1 compressed Ps-file), DESY 94-124 figure file
replaced by uuencoded fil
Low- and high-mass components of the photon distribution functions
The structure of the general solution of the inhomogeneous evolution
equations allows the separation of a photon structure function into
perturbative (``anomalous") and non-perturbative contributions. The former part
is fully calculable, and can be identified with the high-mass contributions to
the dispersion integral in the photon mass. Properly normalized ``state"
distributions can be defined, where the \gamma\to\qqbar splitting probability
is factored out. These state distributions are shown to be useful in the
description of the hadronic event properties, and necessary for a proper
eikonalization of jet cross sections. Convenient parametrizations are provided
both for the state and for the full anomalous parton distributions. The
non-perturbative parts of the parton distribution functions of the photon are
identified with the low-mass contributions to the dispersion integral. Their
normalizations, as well as the value of the scale at which the
perturbative parts vanish, are fixed by approximating the low-mass
contributions by a discrete, finite sum of vector mesons. The shapes of these
hadronic distributions are fitted to the available data on .
Parametrizations are provided for GeV and GeV, both in the
DIS and the factorization schemes. The full
parametrizations are extended towards virtual photons. Finally, the often-used
``FKP-plus-TPC/" solution for is commented upon.Comment: 33 pages, Latex, 6 Z-compressed and uuencoded figure
Neurodevelopmental delay: Case definition & guidelines for data collection, analysis, and presentation of immunization safety data
Fatty acid profile and composition of milk protein fraction in dairy cows fed long-chain unsaturated fatty acids during the transition period
The Earth: Plasma Sources, Losses, and Transport Processes
This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed
Genome-wide interaction study of a proxy for stress-sensitivity and its prediction of major depressive disorder
Individual response to stress is correlated with neuroticism and is an important predictor of both neuroticism and the onset of major depressive disorder (MDD). Identification of the genetics underpinning individual differences in response to negative events (stress-sensitivity) may improve our understanding of the molecular pathways involved, and its association with stress-related illnesses. We sought to generate a proxy for stress-sensitivity through modelling the interaction between SNP allele and MDD status on neuroticism score in order to identify genetic variants that contribute to the higher neuroticism seen in individuals with a lifetime diagnosis of depression compared to unaffected individuals. Meta-analysis of genome-wide interaction studies (GWIS) in UK Biobank (N = 23,092) and Generation Scotland: Scottish Family Health Study (N = 7,155) identified no genome-wide significance SNP interactions. However, gene-based tests identified a genome-wide significant gene, ZNF366, a negative regulator of glucocorticoid receptor function implicated in alcohol dependence (p = 1.48x10-7; Bonferroni-corrected significance threshold p < 2.79x10-6). Using summary statistics from the stress-sensitivity term of the GWIS, SNP heritability for stress-sensitivity was estimated at 5.0%. In models fitting polygenic risk scores of both MDD and neuroticism derived from independent GWAS, we show that polygenic risk scores derived from the UK Biobank stress-sensitivity GWIS significantly improved the prediction of MDD in Generation Scotland. This study may improve interpretation of larger genome-wide association studies of MDD and other stress-related illnesses, and the understanding of the etiological mechanisms underpinning stress-sensitivity
The design, construction, and commissioning of the KATRIN experiment
The KArlsruhe TRItium Neutrino (KATRIN) experiment, which aims to make a direct and model-independent determination of the absolute neutrino mass scale, is a complex experiment with many components. More than 15 years ago, we published a technical design report (TDR) [1] to describe the hardware design and requirements to achieve our sensitivity goal of 0.2 eV at 90% C.L. on the neutrino mass. Since then there has been considerable progress, culminating in the publication of first neutrino mass results with the entire beamline operating [2]. In this paper, we document the current state of all completed beamline components (as of the first neutrino mass measurement campaign), demonstrate our ability to reliably and stably control them over long times, and present details on their respective commissioning campaigns
Integrating sequence and array data to create an improved 1000 Genomes Project haplotype reference panel
A major use of the 1000 Genomes Project (1000GP) data is genotype imputation in genome-wide association studies (GWAS). Here we develop a method to estimate haplotypes from low-coverage sequencing data that can take advantage of single-nucleotide polymorphism (SNP) microarray genotypes on the same samples. First the SNP array data are phased to build a backbone (or 'scaffold') of haplotypes across each chromosome. We then phase the sequence data 'onto' this haplotype scaffold. This approach can take advantage of relatedness between sequenced and non-sequenced samples to improve accuracy. We use this method to create a new 1000GP haplotype reference set for use by the human genetic community. Using a set of validation genotypes at SNP and bi-allelic indels we show that these haplotypes have lower genotype discordance and improved imputation performance into downstream GWAS samples, especially at low-frequency variants. © 2014 Macmillan Publishers Limited. All rights reserved
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