Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA

An investigation of the hadronic final state in diffractive and non--diffractive deep--inelastic electron--proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo --rapidity around the proton remnant direction. The transverse energy flow in the hadronic final state is evaluated using a set of estimators which quantify topological properties. Using available Monte Carlo QCD calculations, it is demonstrated that the final state in diffractive DIS exhibits the features expected if the interaction is interpreted as the scattering of an electron off a current quark with associated effects of perturbative QCD. A model in which deep--inelastic diffraction is taken to be the exchange of a pomeron with partonic structure is found to reproduce the measurements well. Models for deep--inelastic $ep$ scattering, in which a sizeable diffractive contribution is present because of non--perturbative effects in the production of the hadronic final state, reproduce the general tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil

A Search for Selectrons and Squarks at HERA

Data from electron-proton collisions at a center-of-mass energy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal supersymmetric model. The decays of selectrons and squarks into the lightest supersymmetric particle lead to final states with an electron and hadrons accompanied by large missing energy and transverse momentum. No signal is found and new bounds on the existence of these particles are derived. At 95% confidence level the excluded region extends to 65 GeV for selectron and squark masses, and to 40 GeV for the mass of the lightest supersymmetric particle.Comment: 13 pages, latex, 6 Figure

The importance of weather and climate to energy systems: a workshop on next generation challenges in energy-climate modelling

Over 80 international participants, representing weather, climate, and energy systems research, joined two 4-hour remote sessions to highlight and prioritize ongoing and future challenges in energy-climate modelling. The workshop had two primary goals: to build a deeper engagement across the “energy” and “climate” research communities, and to identify and begin to address the scientific challenges associated with modelling climate risk in energy systems

Reply to Elmendorf and Ettinger: Photoperiod playsa dominantand irreplaceable role in triggering secondary growth resumption

In their Letter, Elmendorf and Ettinger (1) question the dominant role of photoperiod in driving secondary growth resumption (hereafter referred to as xylem formation onset) of the Northern Hemisphere conifers, recently reported by Huang et al. (2). Their opinions are grounded on the following three aspects, including 1) the seasonality of the photoperiod, 2) the dependence of the predictor variables (e.g., photoperiod, forcing, and chilling) on the response variable (the date of onset of xylem formation, day of the year [DOY]), and 3) the limited value of the obtained models for interannual forecasting. We think they bring up an interesting issue that deserves further discussion and clarification. Photoperiod is acknowledged to regulate spring bud swelling while wood formation starts (3, 4). Although photoperiod seasonality occurs at each site, its influence is marginal in our study given that the analysis involved comparisons among sites across the Northern Hemisphere. Our conclusion that photoperiod plays a dominant role was built upon the combination of several coherent pieces of evidence, rather than “the crux of Huang et al….” as they pointed out. First, we clearly stated that model 2, which modeled DOY as a function of the mean annual temperature of the site (MAT), forcing, chilling, and soil moisture, was considered the best model in terms of parsimony according to minimum Akaike information criterion and Bayesian information criterion, rather than R2 as referred to in their Letter. Second, photoperiod interacted with MAT and can explain 61.7% of the variance of MAT alone (2). Therefore, we concluded that secondary growth resumption was driven primarily by MAT and photoperiod or by their interaction, which is challenging to be disentangled without experimental data, we agree. In terms of biological functioning, they play an ..

A Measurement of the Proton Structure Function F ⁣2(x,Q2)F_{\!2}(x,Q^2)

A measurement of the proton structure function $F_{\!2}(x,Q^2)$ is reported for momentum transfer squared $Q^2$ between 4.5 $GeV^2$ and 1600 $GeV^2$ and for Bjorken $x$ between $1.8\cdot10^{-4}$ and 0.13 using data collected by the HERA experiment H1 in 1993. It is observed that $F_{\!2}$ increases significantly with decreasing $x$, confirming our previous measurement made with one tenth of the data available in this analysis. The $Q^2$ dependence is approximately logarithmic over the full kinematic range covered. The subsample of deep inelastic events with a large pseudo-rapidity gap in the hadronic energy flow close to the proton remnant is used to measure the "diffractive" contribution to $F_{\!2}$.Comment: 32 pages, ps, appended as compressed, uuencoded fil

The genetic architecture of the human cerebral cortex

INTRODUCTION The cerebral cortex underlies our complex cognitive capabilities. Variations in human cortical surface area and thickness are associated with neurological, psychological, and behavioral traits and can be measured in vivo by magnetic resonance imaging (MRI). Studies in model organisms have identified genes that influence cortical structure, but little is known about common genetic variants that affect human cortical structure. RATIONALE To identify genetic variants associated with human cortical structure at both global and regional levels, we conducted a genome-wide association meta-analysis of brain MRI data from 51,665 individuals across 60 cohorts. We analyzed the surface area and average thickness of the whole cortex and 34 cortical regions with known functional specializations. RESULTS We identified 306 nominally genome-wide significant loci (P < 5 × 10−8) associated with cortical structure in a discovery sample of 33,992 participants of European ancestry. Of the 299 loci for which replication data were available, 241 loci influencing surface area and 14 influencing thickness remained significant after replication, with 199 loci passing multiple testing correction (P < 8.3 × 10−10; 187 influencing surface area and 12 influencing thickness). Common genetic variants explained 34% (SE = 3%) of the variation in total surface area and 26% (SE = 2%) in average thickness; surface area and thickness showed a negative genetic correlation (rG = −0.32, SE = 0.05, P = 6.5 × 10−12), which suggests that genetic influences have opposing effects on surface area and thickness. Bioinformatic analyses showed that total surface area is influenced by genetic variants that alter gene regulatory activity in neural progenitor cells during fetal development. By contrast, average thickness is influenced by active regulatory elements in adult brain samples, which may reflect processes that occur after mid-fetal development, such as myelination, branching, or pruning. When considered together, these results support the radial unit hypothesis that different developmental mechanisms promote surface area expansion and increases in thickness. To identify specific genetic influences on individual cortical regions, we controlled for global measures (total surface area or average thickness) in the regional analyses. After multiple testing correction, we identified 175 loci that influence regional surface area and 10 that influence regional thickness. Loci that affect regional surface area cluster near genes involved in the Wnt signaling pathway, which is known to influence areal identity. We observed significant positive genetic correlations and evidence of bidirectional causation of total surface area with both general cognitive functioning and educational attainment. We found additional positive genetic correlations between total surface area and Parkinson’s disease but did not find evidence of causation. Negative genetic correlations were evident between total surface area and insomnia, attention deficit hyperactivity disorder, depressive symptoms, major depressive disorder, and neuroticism. CONCLUSION This large-scale collaborative work enhances our understanding of the genetic architecture of the human cerebral cortex and its regional patterning. The highly polygenic architecture of the cortex suggests that distinct genes are involved in the development of specific cortical areas. Moreover, we find evidence that brain structure is a key phenotype along the causal pathway that leads from genetic variation to differences in general cognitive function

Subcortical volumes across the lifespan: data from 18,605 healthy individuals aged 3-90 years

Age has a major effect on brain volume. However, the normative studies available are constrained by small sample sizes, restricted age coverage and significant methodological variability. These limitations introduce inconsistencies and may obscure or distort the lifespan trajectories of brain morphometry. In response, we capitalized on the resources of the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Consortium to examine age-related trajectories inferred from cross-sectional measures of the ventricles, the basal ganglia (caudate, putamen, pallidum, and nucleus accumbens), the thalamus, hippocampus and amygdala using magnetic resonance imaging data obtained from 18,605 individuals aged 3-90 years. All subcortical structure volumes were at their maximum value early in life. The volume of the basal ganglia showed a monotonic negative association with age thereafter; there was no significant association between age and the volumes of the thalamus, amygdala and the hippocampus (with some degree of decline in thalamus) until the sixth decade of life after which they also showed a steep negative association with age. The lateral ventricles showed continuous enlargement throughout the lifespan. Age was positively associated with inter-individual variability in the hippocampus and amygdala and the lateral ventricles. These results were robust to potential confounders and could be used to examine the functional significance of deviations from typical age-related morphometric patterns.Education and Child Studie

The influence of MatrigelTM or growth factor reduced MatrigelTMo n human intervertebral disc cell growth and proliferation

MatrigelTM (reconstituted basement membrane extract) is a potent inducer of cell growth and differentiation in vitro. This study examined phenotypic variation and proliferative responses of human annular intervertebral disc cells in vitro in MatrigelTM and Growth Factor Reduced MatrigelTM (GFR-MatrigelTM). Cells from age- and gender-matched control subjects and patients with degenerative disc disease were grown either on the surface of, or suspended within, either matrices. Disc cells grew well on top of both matrices with cells spontaneously forming cell projections. Cells grown within either matrix migrated within the gel to form colonies. Increased colony formation within the matrices was seen with young control and patient cells (p<0.05). Old and young control and patient cells showed increased proliferation within GFR-MatrigelTM compared to MatrigelTMW. hen grown on the matrix surface, young patient and control donor cells showed increased proliferation on GFR-MatrigelTMc ompared to MatrigelTM. Cellular proliferation was significantly greater inside a 3-dimensional environment than a twodimensional surface monolayer environment. Disc cells had increased proliferation when grown in or on GFRMatrigelTMc ompared to MatrigelTMT. hese studies serve as a baseline for subsequent investigations regarding effects of cytokines on disc cells and increase our knowledge of the influence of extracellular matrices on disc cell proliferation