2,655 research outputs found
Variational Formulation of Macro-Particle Models for Electromagnetic Plasma Simulations
A variational method is used to derive a self-consistent macro-particle model
for relativistic electromagnetic kinetic plasma simulations. Extending earlier
work [E. G. Evstatiev and B. A. Shadwick, J. Comput. Phys., vol. 245, pp.
376-398, 2013], the discretization of the electromagnetic Low Lagrangian is
performed via a reduction of the phase-space distribution function onto a
collection of finite-sized macro-particles of arbitrary shape and
discretization of field quantities onto a spatial grid. This approach may be
used with both lab frame coordinates or moving window coordinates; the latter
can greatly improve computational efficiency for studying some types of
laser-plasma interactions. The primary advantage of the variational approach is
the preservation of Lagrangian symmetries, which in our case leads to energy
conservation and thus avoids difficulties with grid heating. Additionally, this
approach decouples particle size from grid spacing and relaxes restrictions on
particle shape, leading to low numerical noise. The variational approach also
guarantees consistent approximations in the equations of motion and is amenable
to higher order methods in both space and time. We restrict our attention to
the 1-1/2 dimensional case (one coordinate and two momenta). Simulations are
performed with the new models and demonstrate energy conservation and low
noise.Comment: IEEE Transaction on Plasma Science (TPS) Special Issue: Plenary and
Invited Papers of the Pulsed Power and Plasma Science Conference (PPPS 2013
The Activity of the Serotonin Receptor 2C is Regulated by Alternative Splicing
The central nervous system-specific serotonin receptor 2C (5HT2C) controls key physiological functions, such as food intake, anxiety, and motoneuron activity. Its deregulation is involved in depression, suicidal behavior, and spasticity, making it the target for antipsychotic drugs, appetite controlling substances, and possibly anti-spasm agents. Through alternative pre-mRNA splicing and RNA editing, the 5HT2C gene generates at least 33 mRNA isoforms encoding 25 proteins. The 5HT2C is a G-protein coupled receptor that signals through phospholipase C, influencing the expression of immediate/early genes like c-fos. Most 5HT2C isoforms show constitutive activity, i.e., signal without ligand binding. The constitutive activity of 5HT2C is decreased by pre-mRNA editing as well as alternative pre-mRNA splicing, which generates a truncated isoform that switches off 5HT2C receptor activity through heterodimerization; showing that RNA processing regulates the constitutive activity of the 5HT2C system. RNA processing events influencing the constitutive activity target exon Vb that forms a stable double stranded RNA structure with its downstream intron. This structure can be targeted by small molecules and oligonucleotides that change exon Vb alternative splicing and influence 5HT2C signaling in mouse models, leading to a reduction in food intake. Thus, the 5HT2C system is a candidate for RNA therapy in multiple models of CNS disorders
The relevance of ERTS-1 data to the state of Ohio
There are no author-identified significant results in this report
Work-life conflicts and health among Swiss physicians--in comparison with other university graduates and with the general Swiss working population
QUESTION UNDER STUDY: The present study aimed to compare the prevalence of work-life conflicts and the health status of physicians, with a representative sample of university graduates as well as with a representative sample of the general Swiss working population. Furthermore, it aimed to analyse whether work-life conflicts correlate with the health of physicians, as it does in the general working population. METHODS: The present cross-sectional study analysed data from 2007 originating from the SwissMedCareer Study (a prospective cohort study of physicians who graduated in 2001; n = 543) and the Swiss Household Panel (a representative Swiss survey on living and working conditions; university graduates of the same age range: n = 172, general working population of the same age range: n = 670). Data were analysed with Chi2 tests, correlations and logistic regressions. RESULTS: Physicians reported strong time-based as well as strain-based work-life conflicts more frequently than university graduates and the general working population. Significantly more physicians reported "moderate" to "very poor" health than the other two samples. Surprisingly, on the other side of the scale ("very good" health), physicians outnumbered the other samples too. Strong associations between work-life conflict and self-rated health as well as various health complaints were found for physicians. CONCLUSION: The high prevalence of work-life conflicts may explain the comparably high prevalence of poor self-rated health in the physicians' sample
Pancreatic acinar cell carcinoma : an analysis of cell lineage markers, P53 expression, and Ki-ras mutation
In a series of 22 pancreatic acinar cell carcinomas, including two acinar cystadenocarcinomas, cellular differentiation was analyzed by immunocytochemistry and electron microscopy. In addition, overexpression of p53 protein and Ki-ras codon 12 mutation was studied. Four of the 20 noncystic acinar cell carcinomas showed a pure acinar pattern, nine an acinar-solid, and seven a solid pattern. All tumors stained for at least one of the following pancreatic acinar markers: trypsin (21 of 22), lipase (19 of 22), chymotrypsin (13 of 22), phospholipase A2 (nine of 22), and pancreatic stone protein (19 of 22). One-third of the tumors expressed neuroendocrine markers (synaptophysin, eight of 22; chromogranin A, six of 21) and duct cell markers (CA19.9, nine of 21; B72.3, six of 21). Cellular coexpression of trypsin and synaptophysin was demonstrated in one tumor. Electron microscopy revealed zymogen granules (nine of nine). In only one of 16 tumors a Ki-ras mutation at codon 12 was found, whereas in none of 19 tumors could overexpression of p53 protein be demonstrated. The results suggest that acinar cell carcinomas show obvious capacity to differentiate into several directions, but nevertheless constitute an entity different from ductal adenocarcinomas or endocrine tumors
Do Winter Canola Hybrids and Open-Pollinated Varieties Respond Differently to Seeding Rate?
Several producers have turned to planting canola in 30-in. rows as a strategy to take advantage of residue management options (e.g. planter-mounted residue managers and strip tillage) to facilitate planting canola in high-residue cropping systems. Canola hybrids are gaining acres in the southern Great Plains and may require different management than the traditional open-pollinated cultivars. The objective of this study was to determine the effect of seeding rate on winter survival and yield of hybrid and open-pollinated winter canola cultivars in 30-in. and 9-in. rows. Experiments were conducted in 2013-2014, 2014-2015, and 2015-2016 at two K-State Research and Extension facilities. Treatments were four locally adapted cultivars (two hybrids and two open-pollinated cultivars) and three or five seeding rates for a total of twelve or twenty treatments in each experiment. Due to nearly complete winter stand loss of hybrids in the experiment planted in 2013, only open-pollinated cultivars were harvested. No experiments were harvested for yield in 2015 because of nearly complete stand loss in all treatments at all locations. In both row spacings, fall stands tended to increase with increasing seeding rates, and hybrids tended to establish more plants than open-pollinated cultivars. Differences in stands due to seeding rate were somewhat less evident in the spring, but stand differences due to cultivars were more evident. Winter survival tended to increase as the number of plants present in the fall decreased, whether that was due to seeding rate or other factors. Bloom occasionally was delayed, and harvested seed moisture tended to be greater when fewer plants were present in the spring, likely due to a greater percentage of buds forming on branches. Seeding rate had a minimal impact on yields in 30-in. rows, with hybrids and open-pollinated cultivars responding similarly in most cases. In 9-in. rows, seeding rate did not affect yields in 2014. In 2016, both hybrids and open-pollinated cultivars maximized yield at 300,000 seeds per acre in 9-in. rows, but hybrids maintained greater yields than open-pollinated cultivars at sub-optimal seeding rates
Отказоустойчивый многофазный асинхронный электропривод с несинусоидальными токами
Рассмотрен принцип построения многофазного асинхронного электропривода, позволяющего при неоднократных отказах преобразователя частоты и двигателя обеспечить отказоустойчивое управление, на основе программируемых несинусоидальных токов с восстановлением работоспособности за счет активизации алгоритма восстановления в управляющем микроконтроллере. Приведены результаты моделирования для аварийной ситуации типа "обрыв фазы" для случая трехфазного двигателя с частичным восстановлением работоспособности асинхронного двигателя
An exploratory study on the factors affecting the mental health and well-being of frontline workers in homeless services
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