3,904 research outputs found

    On the formation of the welding seams with high speed

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    Целью настоящей работы является определение направлений исследований по установлению возможности повышения качества формирования сварочных швов с повышенной скоростью формирования тела шва. В статье вопрос решается путём отклонения сварочной дуги углом вперед, поперечным магнитным полем. Дополнительное магнитное поле в зоне сварки генерируют, пропуская часть сварочного тока по присадочной проволоке. Проволока подается в сварочную ванну позади дуги параллельно электроду в плоскости свариваемого стыка, в направлении, противоположном току дуги. Проведенный анализ отечественных и зарубежных литературных источников по рассматриваемой теме показал, что современный подход к определению влияния на повышение качества формирования сварочных швов с повышенной скоростью формирования тела шва, за счет дополнительного поперечного магнитного поля является актуальным в настоящее время и недостаточно изучен. Приведены сведения о формировании тела шва при скоростной сварке вольфрамовым электродом с присадочной проволокой, которые могут быть использованы для повышения производительности сварочных работ.The aim of this work is to determine the areas of research to establish the possibility of improving the quality of the formation of welds with an increased rate of formation of the joint body. In the article the problem is solved by the deviation of the arc angle forward transverse magnetic field. Additional magnetic field generated in the welding zone by passing part of the welding current for the filler wire. The wire is fed into the weld puddle behind the arc electrode in the plane parallel to the welded joint, in a direction opposite to the arc current. The analysis of domestic and foreign literature on the topic has shown that the modern approach to determine the effect on the improvement of quality of formation of welds with an increased rate of formation of the joint body, due to the additional transverse magnetic field is relevant in the present and not fully understood. Information is given about the formation of a seam in the tungsten electrode welding with filler wire, which can be used to improve the performance of welding

    Genetic associations with learning over 100 days of practice

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    Cognitive performance is both heritable and sensitive to environmental inputs and sustained practice over time. However, it is currently unclear how genetic effects on cognitive performance change over the course of learning. We examine how polygenic scores (PGS) created from genome-wide association studies of educational attainment and cognitive performance are related to improvements in performance across nine cognitive tests (measuring perceptual speed, working memory, and episodic memory) administered to 131 adults (N = 51, ages = 20–31, and N = 80, ages = 65–80 years) repeatedly across 100 days. We observe that PGS associations with performance on a given task can change over the course of learning, with the specific pattern of change in associations differing across tasks. PGS correlations with pre-test to post-test scores may mask variability in how soon learning occurs over the course of practice. The associations between PGS and learning do not appear to simply reconstitute patterns of association between baseline performance and subsequent learning. Associations involving PGSs, however, were small with large confidence intervals. Intensive longitudinal research such as that described here may be of substantial value for clarifying the genetics of learning when implemented as far larger scale

    Impact of Electron Solvation on Ice Structures at the Molecular Scale

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    We determine the impact of electron solvation on D2_2O structures adsorbed on Cu(111) with low temperature scanning tunneling microscopy, two-photon photoemission, and ab initio theory. UV photons generating solvated electrons lead not only to transient, but also to permanent structural changes through the rearrangement of individual molecules. The persistent changes occur near sites with a high density of dangling OH groups that facilitate electron solvation. We conclude that energy dissipation during solvation triggers permanent molecular rearrangement via vibrational excitation

    Novel multiple sclerosis susceptibility loci implicated in epigenetic regulation

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    We conducted a genome-wide association study (GWAS) on multiple sclerosis (MS) susceptibility in German cohorts with 4888 cases and 10,395 controls. In addition to associations within the major histocompatibility complex (MHC) region, 15 non-MHC loci reached genome-wide significance. Four of these loci are novel MS susceptibility loci. They map to the genes L3MBTL3, MAZ, ERG, and SHMT1. The lead variant at SHMT1 was replicated in an independent Sardinian cohort. Products of the genes L3MBTL3, MAZ, and ERG play important roles in immune cell regulation. SHMT1 encodes a serine hydroxymethyltransferase catalyzing the transfer of a carbon unit to the folate cycle. This reaction is required for regulation of methylation homeostasis, which is important for establishment and maintenance of epigenetic signatures. Our GWAS approach in a defined population with limited genetic substructure detected associations not found in larger, more heterogeneous cohorts, thus providing new clues regarding MS pathogenesis

    Search for associated Higgs boson production using like charge dilepton events in p(p)over-bar collisions at root s=1.96 TeV

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    We present a search for associated Higgs boson production in the process p (p) over bar -> W/ZH -> l(+/-)l'(+/-) + X in ee, e mu, and mu mu final states. The search is based on data collected by the D0 experiment at the Fermilab Tevatron Collider at root s = 1.96 TeV corresponding to 5.3 fb(-1) of integrated luminosity. We require two isolated leptons (electrons or muons) with the same electric charge and additional kinematic requirements. No significant excess above background is observed, and we set 95% C. L. observed (expected) upper limits on ratio of the production cross section to the standard model prediction of 6.4 (7.3) for a Higgs boson mass of 165 GeV and 13.5 (19.8) for a mass of 115 GeV
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