60 research outputs found
Dijet Production at HERA in Next-to-Leading Order
Two-jet cross sections in deep inelastic scattering at HERA are calculated in
next-to-leading order. The QCD corrections are implemented in a new
jets event generator, MEPJET, which allows to analyze
arbitrary jet definition schemes and general cuts in terms of parton 4-momenta.
First results are presented for the JADE, the cone and the schemes. For
the -scheme, disagreement with previous results and large radiative
corrections and recombination scheme dependencies are traced to a common
origin.Comment: 11 pages (Latex) plus 5 figures enclosed as a uuencoded postscript
file. The complete paper, including figures, is also available via anonymous
ftp at ftp://www-ttp.physik.uni-karlsruhe.de/ , or via www at
http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints
QCD Corrections to Jet Cross Sections in DIS
Next-to-leading order corrections to jet cross sections in deep inelastic
scattering at HERA are studied. The predicted jet rates allow for a precise
determination of at HERA over a wide range of . We
argue, that the ``natural'' renormalization and factorization scale is set by
the average of the jets in the Breit frame and suggest to divide the
data in corresponding intervals. Some implications for the
determination of the gluon density and the associated forward jet production in
the low regime at HERA are briefly discussed.Comment: Invited talk given at the Zeuthen Workshop on Elementary Particle
Theory, "QCD and QED in Higher Orders", Rheinsberg, Germany, 21-26 April
1996; presented by E. Mirkes. 6 pages, 4 figures. The complete paper,
including figures, is also available via anonymous ftp at
ftp://www-ttp.physik.uni-karlsruhe.de/ , or via www at
http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints
Experimentelle Methoden in der Informatik
Dieser Report enthaelt die Ausarbeitungen von Vortraegen aus einem
Seminar gleichen Namens, das am 3./4. Juli 1995 am Institut f"ur
Programmstrukturen und Datenorganisation unter Leitung von Walter
Tichy, Ernst Heinz, Paul Lukowicz und Lutz Prechelt stattfand.
Die Artikel geben einen Ueberblick ueber die moegliche Funktion
und den Stellenwert experimentellen Vorgehens in verschiedenen Teilen
der Informatik, sowie einerseits deren wissenschaftstheoretische
Grundlage und andererseits ihre bisherige praktische Umsetzung
Allocating the Burdens of Climate Action: Consumption-Based Carbon Accounting and the Polluter-Pays Principle
Action must be taken to combat climate change. Yet, how the costs of climate action should be allocated among states remains a question. One popular answer—the polluter-pays principle (PPP)—stipulates that those responsible for causing the problem should pay to address it. While intuitively plausible, the PPP has been subjected to withering criticism in recent years. It is timely, following the Paris Agreement, to develop a new version: one that does not focus on historical production-based emissions but rather allocates climate burdens in proportion to each state’s annual consumption-based emissions. This change in carbon accounting results in a fairer and more environmentally effective principle for distributing climate duties
LHC Phenomenology for String Hunters
We consider extensions of the standard model based on open strings ending on
D-branes, with gauge bosons due to strings attached to stacks of D-branes and
chiral matter due to strings stretching between intersecting D-branes. Assuming
that the fundamental string mass scale is in the TeV range and the theory is
weakly coupled, we discuss possible signals of string physics at the Large
Hadron Collider (LHC). In previous works, direct channel excitations of Regge
recurrences in parton-parton scattering supplied the outstanding new signature.
The present work considers the deviation from standard model expectations for
the 4-fermion processes qq\to qq and qq' \to qq', in which the s-channel
excitation of string resonances is absent. In this case, we find that
Kaluza-Klein recurrences at masses somewhat less than the string scale generate
effective 4-fermion contact terms which can significantly enhance the dijet R
ratio above its QCD value of about 0.6. The simultaneous observation of a
nearby resonant structure in the dijet mass spectrum would provide a "smoking
gun" for TeV scale string theory. In this work, we also show that (1) for
M_{string}<3.5 TeV, the rates for various topologies arising from the pp \to
Z^0 + jet channel could deviate significantly from standard model predictions
and (2) that the sizeable cross sections for Regge recurrences can allow a
6\sigma discovery for string scales as large as 3 TeV after about 1 year of LHC
operation at \sqrt{s} =10 TeV and \int L dt ~ 100 pb^{-1}.Comment: Typographical error in equations (17), (18), (19), and (20) has been
correcte
New Physics backgrounds to the H -> WW search at the LHC?
The searches for H -> WW events at the LHC use data driven techniques for
estimating the q qbar -> WW background, by normalizing the background cross
section to data in a control region. We investigate the possibility that new
physics sources which mainly contribute to the control region lead to an
overestimate of Standard Model backgrounds to the Higgs boson signal and, thus,
to an underestimate of the H -> WW signal. A supersymmetric scenario with heavy
squarks and gluinos but charginos in the 200 to 300 GeV region and somewhat
lighter sleptons can lead to such a situation.Comment: 13 pages, 3 figures, 1 table. v2: matches version published in PL
Reflections
The American Society of International Law Committee recommended that the Manley 0. Hudson Medal be awarded to Professor Eric Stein for his lifetime of significant contributions to international and comparative law. Stein, the Hessel E. Yntema Professor of Law, Emeritus, at the University of Michigan Law School, had been an active supporter of ASIL as Honorary Vice President, Counsellor, and Honorary Editor of, and frequent contributor to, the American Journal of International Law. His many books and articles established him as a leading thinker and writer on European Community law and on what he described in a famous article as the Uses, Misuses, and Nonuses of Comparative Law
Myelin-mediated inhibition of oligodendrocyte precursor differentiation can be overcome by pharmacological modulation of Fyn-RhoA and protein kinase C signalling
Failure of oligodendrocyte precursor cell (OPC) differentiation contributes significantly to failed myelin sheath regeneration (remyelination) in chronic demyelinating diseases. Although the reasons for this failure are not completely understood, several lines of evidence point to factors present following demyelination that specifically inhibit differentiation of cells capable of generating remyelinating oligodendrocytes. We have previously demonstrated that myelin debris generated by demyelination inhibits remyelination by inhibiting OPC differentiation and that the inhibitory effects are associated with myelin proteins. In the present study, we narrow down the spectrum of potential protein candidates by proteomic analysis of inhibitory protein fractions prepared by CM and HighQ column chromatography followed by BN/SDS/SDS–PAGE gel separation using Nano-HPLC-ESI-Q-TOF mass spectrometry. We show that the inhibitory effects on OPC differentiation mediated by myelin are regulated by Fyn-RhoA-ROCK signalling as well as by modulation of protein kinase C (PKC) signalling. We demonstrate that pharmacological or siRNA-mediated inhibition of RhoA-ROCK-II and/or PKC signalling can induce OPC differentiation in the presence of myelin. Our results, which provide a mechanistic link between myelin, a mediator of OPC differentiation inhibition associated with demyelinating pathologies and specific signalling pathways amenable to pharmacological manipulation, are therefore of significant potential value for future strategies aimed at enhancing CNS remyelination
Prevalence and incidence of iron deficiency in European community-dwelling older adults : An observational analysis of the DO-HEALTH trial
Background and aim
Iron deficiency is associated with increased morbidity and mortality in older adults. However, data on its prevalence and incidence among older adults is limited. The aim of this study was to investigate the prevalence and incidence of iron deficiency in European community-dwelling older adults aged ≥ 70 years.
Methods
Secondary analysis of the DO-HEALTH trial, a 3-year clinical trial including 2157 community-dwelling adults aged ≥ 70 years from Austria, France, Germany, Portugal and Switzerland. Iron deficiency was defined as soluble transferrin receptor (sTfR) > 28.1 nmol/L. Prevalence and incidence rate (IR) of iron deficiency per 100 person-years were examined overall and stratified by sex, age group, and country. Sensitivity analysis for three commonly used definitions of iron deficiency (ferritin 1.5) were also performed.
Results
Out of 2157 participants, 2141 had sTfR measured at baseline (mean age 74.9 years; 61.5% women). The prevalence of iron deficiency at baseline was 26.8%, and did not differ by sex, but by age (35.6% in age group ≥ 80, 29.3% in age group 75–79, 23.2% in age group 70–74); P 1.5. Occurrences of iron deficiency were observed with IR per 100 person-years of 9.2 (95% CI 8.3–10.1) and did not significantly differ by sex or age group. The highest IR per 100 person-years was observed in Austria (20.8, 95% CI 16.1–26.9), the lowest in Germany (6.1, 95% CI 4.7–8.0). Regarding the other definitions of iron deficiency, the IR per 100 person-years was 4.5 (95% CI 4.0–4.9) for ferritin 1.5.
Conclusions
Iron deficiency is frequent among relatively healthy European older adults, with people aged ≥ 80 years and residence in Austria and Portugal associated with the highest risk
- …