Next-to-Leading Order QCD Corrections to Jet Cross Sections and Jet Rates in Deeply Inelastic Electron Proton Scattering

Jet cross sections in deeply inelastic scattering in the case of transverse photon exchange for the production of (1+1) and (2+1) jets are calculated in next-to-leading order QCD (here the `+1' stands for the target remnant jet, which is included in the jet definition for reasons that will become clear in the main text). The jet definition scheme is based on a modified JADE cluster algorithm. The calculation of the (2+1) jet cross section is described in detail. Results for the virtual corrections as well as for the real initial- and final state corrections are given explicitly. Numerical results are stated for jet cross sections as well as for the ratio \sigma_{\mbox{\small (2+1) jet}}/\sigma_{\mbox{\small tot}} that can be expected at E665 and HERA. Furthermore the scale ambiguity of the calculated jet cross sections is studied and different parton density parametrizations are compared.Comment: 40 pages, LBL-34147 (Latex file). (figures available by mail on request (send e-mail to [email protected]), please include your address such that it can be used as an address label

Combining QCD Matrix Elements at Next-to-Leading Order with Parton Showers in Electroproduction

We present a method to combine next-to-leading order (NLO) matrix elements in QCD with leading logarithmic parton showers by applying a suitably modified version of the phase-space-slicing method. The method consists of subsuming the NLO corrections into a scale-dependent phase-space-slicing parameter, which is then automatically adjusted to cut out the leading order, virtual, soft and collinear contributions in the matrix element calculation. In this way a positive NLO weight is obtained, which can be redistributed by a parton shower algortihm. As an example, we display the method for single-jet inclusive cross sections at O(alpha_s) in electroproduction. We numerically compare the modified version of the phase-space-slicing method with the standard approach and find very good agreement on the percent level.Comment: 21 pages, 2 eps figures. Revised section 2. To appear in PR

Automatic Assignment of EC Numbers

A wide range of research areas in molecular biology and medical biochemistry require a reliable enzyme classification system, e.g., drug design, metabolic network reconstruction and system biology. When research scientists in the above mentioned areas wish to unambiguously refer to an enzyme and its function, the EC number introduced by the Nomenclature Committee of the International Union of Biochemistry and Molecular Biology (IUBMB) is used. However, each and every one of these applications is critically dependent upon the consistency and reliability of the underlying data for success. We have developed tools for the validation of the EC number classification scheme. In this paper, we present validated data of 3788 enzymatic reactions including 229 sub-subclasses of the EC classification system. Over 80% agreement was found between our assignment and the EC classification. For 61 (i.e., only 2.5%) reactions we found that their assignment was inconsistent with the rules of the nomenclature committee; they have to be transferred to other sub-subclasses. We demonstrate that our validation results can be used to initiate corrections and improvements to the EC number classification scheme

Diverging climate trends in Mongolian taiga forests influence growth and regeneration of Larix sibirica

Central and semiarid north-eastern Asia was subject to twentieth century warming far above the global average. Since forests of this region occur at their drought limit, they are particularly vulnerable to climate change. We studied the regional variations of temperature and precipitation trends and their effects on tree growth and forest regeneration in Mongolia. Tree-ring series from more than 2,300 trees of Siberian larch (Larix sibirica) collected in four regions of Mongolia’s forest zone were analyzed and related to available weather data. Climate trends underlie a remarkable regional variation leading to contrasting responses of tree growth in taiga forests even within the same mountain system. Within a distance of a few hundred kilometers (140–490 km), areas with recently reduced growth and regeneration of larch alternated with regions where these parameters remained constant or even increased. Reduced productivity could be correlated with increasing summer temperatures and decreasing precipitation; improved growth conditions were found at increasing precipitation, but constant summer temperatures. An effect of increasing winter temperatures on tree-ring width or forest regeneration was not detectable. Since declines of productivity and regeneration are more widespread in the Mongolian taiga than the opposite trend, a net loss of forests is likely to occur in the future, as strong increases in temperature and regionally differing changes in precipitation are predicted for the twenty-first century

Mass spectra of doubly heavy Omega_QQ' baryons

We evaluate the masses of baryons composed of two heavy quarks and a strange quark with account for spin-dependent splittings in the framework of potential model with the KKO potential motivated by QCD with a three-loop beta-function for the effective charge consistent with both the perturbative limit at short distances and linear confinement term at long distances between the quarks. The factorization of dynamics is supposed and explored in the nonrelativistic Schroedinger equation for the motion in the system of two heavy quarks constituting the doubly heavy diquark and the strange quark interaction with the diquark. The limits of approach, its justification and uncertainties are discussed. Excited quasistable states are classified by the quantum numbers of heavy diquark composed by the heavy quarks of the same flavor.Comment: 14 pages, revtex4-file, 3 eps-figures, 5 tables, typos correcte

Simulating the carbon balance of a temperate larch forest under various meteorological conditions

<p>Abstract</p> <p>Background</p> <p>Changes in the timing of phenological events may cause the annual carbon budget of deciduous forests to change. Therefore, one should take such events into account when evaluating the effects of global warming on deciduous forests. In this article, we report on the results of numerical experiments done with a model that includes a phenological module simulating the timing of bud burst and other phenological events and estimating maximum leaf area index.</p> <p>Results</p> <p>This study suggests that the negative effects of warming on tree productivity (net primary production) outweigh the positive effects of a prolonged growing season. An increase in air temperature by 3°C (5°C) reduces cumulative net primary production by 21.3% (34.2%). Similarly, cumulative net ecosystem production (the difference between cumulative net primary production and heterotrophic respiration) decreases by 43.5% (64.5%) when temperatures are increased by 3°C (5°C). However, the positive effects of CO₂enrichment (2 × CO₂) outweigh the negative effects of warming (<5°C).</p> <p>Conclusion</p> <p>Although the model was calibrated and validated for a specific forest ecosystem, the implications of the study may be extrapolated to deciduous forests in cool-temperate zones. These forests share common features, and it can be conjectured that carbon stocks would increase in such forests in the face of doubled CO₂and increased temperatures as long as the increase in temperature does not exceed 5°C.</p

Impacts of climate change on plant diseases – opinions and trends

There has been a remarkable scientific output on the topic of how climate change is likely to affect plant diseases in the coming decades. This review addresses the need for review of this burgeoning literature by summarizing opinions of previous reviews and trends in recent studies on the impacts of climate change on plant health. Sudden Oak Death is used as an introductory case study: Californian forests could become even more susceptible to this emerging plant disease, if spring precipitations will be accompanied by warmer temperatures, although climate shifts may also affect the current synchronicity between host cambium activity and pathogen colonization rate. A summary of observed and predicted climate changes, as well as of direct effects of climate change on pathosystems, is provided. Prediction and management of climate change effects on plant health are complicated by indirect effects and the interactions with global change drivers. Uncertainty in models of plant disease development under climate change calls for a diversity of management strategies, from more participatory approaches to interdisciplinary science. Involvement of stakeholders and scientists from outside plant pathology shows the importance of trade-offs, for example in the land-sharing vs. sparing debate. Further research is needed on climate change and plant health in mountain, boreal, Mediterranean and tropical regions, with multiple climate change factors and scenarios (including our responses to it, e.g. the assisted migration of plants), in relation to endophytes, viruses and mycorrhiza, using long-term and large-scale datasets and considering various plant disease control methods

Contrasting Diversity Patterns of Crenarchaeal, Bacterial and Fungal Soil Communities in an Alpine Landscape

International audienceBackground: The advent of molecular techniques in microbial ecology has aroused interest in gaining an understanding about the spatial distribution of regional pools of soil microbes and the main drivers responsible of these spatial patterns. Here, we assessed the distribution of crenarcheal, bacterial and fungal communities in an alpine landscape displaying high turnover in plant species over short distances. Our aim is to determine the relative contribution of plant species composition, environmental conditions, and geographic isolation on microbial community distribution. Methodology/Principal Findings: Eleven types of habitats that best represent the landscape heterogeneity were investigated. Crenarchaeal, bacterial and fungal communities were described by means of Single Strand Conformation Polymorphism. Relationships between microbial beta diversity patterns were examined by using Bray-Curtis dissimilarities and Principal Coordinate Analyses. Distance-based redundancy analyses and variation partitioning were used to estimate the relative contributions of different drivers on microbial beta diversity. Microbial communities tended to be habitat- specific and did not display significant spatial autocorrelation. Microbial beta diversity correlated with soil pH. Fungal beta- diversity was mainly related to soil organic matter. Though the effect of plant species composition was significant for all microbial groups, it was much stronger for Fungi. In contrast, geographic distances did not have any effect on microbial beta diversity. Conclusions/Significance: Microbial communities exhibit non-random spatial patterns of diversity in alpine landscapes. Crenarcheal, bacterial and fungal community turnover is high and associated with plant species composition through different set of soil variables, but is not caused by geographical isolation

Genetic and Evolutionary Analyses of the Human Bone Morphogenetic Protein Receptor 2 (BMPR2) in the Pathophysiology of Obesity

Human bone morphogenetic protein receptor 2 (BMPR2) is essential for BMP signalling and may be involved in the regulation of adipogenesis. The BMPR2 locus has been suggested as target of recent selection in human populations. We hypothesized that BMPR2 might have a role in the pathophysiology of obesity.Evolutionary analyses (dN/dS, Fst, iHS) were conducted in vertebrates and human populations. BMPR2 mRNA expression was measured in 190 paired samples of visceral and subcutaneous adipose tissue. The gene was sequenced in 48 DNA samples. Nine representative single nucleotide polymorphisms (SNPs) were genotyped for subsequent association studies on quantitative traits related to obesity in 1830 German Caucasians. An independent cohort of 925 Sorbs was used for replication. Finally, relation of genotypes to mRNA in fat was examined.The evolutionary analyses indicated signatures of selection on the BMPR2 locus. BMPR2 mRNA expression was significantly increased both in visceral and subcutaneous adipose tissue of 37 overweight (BMI>25 and <30 kg/m²) and 80 obese (BMI>30 kg/m²) compared with 44 lean subjects (BMI< 25 kg/m²) (P<0.001). In a case-control study including lean and obese subjects, two intronic SNPs (rs6717924, rs13426118) were associated with obesity (adjusted P<0.05). Combined analyses including the initial cohort and the Sorbs confirmed a consistent effect for rs6717924 (combined P = 0.01) on obesity. Moreover, rs6717924 was associated with higher BMPR2 mRNA expression in visceral adipose tissue.Combined BMPR2 genotype-phenotype-mRNA expression data as well as evolutionary aspects suggest a role of BMPR2 in the pathophysiology of obesity