4,531 research outputs found
Radiative hydrodynamic modelling and observations of the X-class solar flare on 2011 March 9
We investigated the response of the solar atmosphere to non-thermal electron
beam heating using the radiative transfer and hydrodynamics modelling code
RADYN. The temporal evolution of the parameters that describe the non-thermal
electron energy distribution were derived from hard X-ray observations of a
particular flare, and we compared the modelled and observed parameters. The
evolution of the non-thermal electron beam parameters during the X1.5 solar
flare on 2011 March 9 were obtained from analysis of RHESSI X-ray spectra. The
RADYN flare model was allowed to evolve for 110 seconds, after which the
electron beam heating was ended, and was then allowed to continue evolving for
a further 300s. The modelled flare parameters were compared to the observed
parameters determined from extreme-ultraviolet spectroscopy. The model produced
a hotter and denser flare loop than that observed and also cooled more rapidly,
suggesting that additional energy input in the decay phase of the flare is
required. In the explosive evaporation phase a region of high-density cool
material propagated upward through the corona. This material underwent a rapid
increase in temperature as it was unable to radiate away all of the energy
deposited across it by the non-thermal electron beam and via thermal
conduction. A narrow and high-density ( cm) region at
the base of the flare transition region was the source of optical line emission
in the model atmosphere. The collision-stopping depth of electrons was
calculated throughout the evolution of the flare, and it was found that the
compression of the lower atmosphere may permit electrons to penetrate farther
into a flaring atmosphere compared to a quiet Sun atmosphere.Comment: 12 pages, 12 figure
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Propagation of Pericentral Necrosis During Acetaminophen-Induced Liver Injury: Evidence for Early Interhepatocyte Communication and Information Exchange.
Acetaminophen (APAP)-induced liver injury is clinically significant, and APAP overdose in mice often serves as a model for drug-induced liver injury in humans. By specifying that APAP metabolism, reactive metabolite formation, glutathione depletion, and mitigation of mitochondrial damage within individual hepatocytes are functions of intralobular location, an earlier virtual model mechanism provided the first concrete multiattribute explanation for how and why early necrosis occurs close to the central vein (CV). However, two characteristic features could not be simulated consistently: necrosis occurring first adjacent to the CV, and subsequent necrosis occurring primarily adjacent to hepatocytes that have already initiated necrosis. We sought parsimonious model mechanism enhancements that would manage spatiotemporal heterogeneity sufficiently to enable meeting two new target attributes and conducted virtual experiments to explore different ideas for model mechanism improvement at intrahepatocyte and multihepatocyte levels. For the latter, evidence supports intercellular communication via exosomes, gap junctions, and connexin hemichannels playing essential roles in the toxic effects of chemicals, including facilitating or counteracting cell death processes. Logic requiring hepatocytes to obtain current information about whether downstream and lateral neighbors have triggered necrosis enabled virtual hepatocytes to achieve both new target attributes. A virtual hepatocyte that is glutathione-depleted uses that information to determine if it will initiate necrosis. When a less-stressed hepatocyte is flanked by at least two neighbors that have triggered necrosis, it too will initiate necrosis. We hypothesize that the resulting intercellular communication-enabled model mechanism is analogous to the actual explanation for APAP-induced hepatotoxicity at comparable levels of granularity
Steroid-Responsive Encephalopathy Associated with Autoimmune Thyroiditis Presenting as Confusion, Dysphasia, and Myoclonus
Steroid response encephalopathy associated with autoimmune thyroiditis (SREAT), or Hashimoto's encephalopathy, is a rare disorder believed to be immune-mediated. It is most often characterized by a subacute onset of confusion with altered level of consciousness, seizures, and myoclonus. We describe the case of a 48-year-old gentleman who presented with confusion and dysphasia. Specific clinical features and laboratory results led to a diagnosis of Hashimoto's encephalopathy. This case highlights the core features of this condition and the potential for complete response to steroid therapy
Teaching, Learning, and Leading with Schools and Communities: One Urban University Re-Envisions Teacher Preparation for the Next Generation
Ultimately, the national goals of improving learning outcomes for all students and reducing, if not eliminating, the achievement gap require a teaching corps that brings knowledge and professional competencies to have positive impacts on diverse learners in diverse settings (Gándara & Maxwell-Jolly, 2006). As central actors in schools, teachers have the greatest impact on student achievement (Cochran-Smith & Fries, 2005). Nevertheless, due to varied challenges of preparing high-quality teachers within the context of traditional schools of education, preparation programs have yet to consistently and comprehensively produce teachers who accomplish these outcomes (Ball & Forzani, 2009; Larabee, 2004, 2010). While substantive reform and evidence of improved teacher education emerges (Ball & Forzani, 2009, 2010; Zumwalt & Craig, 2005), systemic change that contributes to better pre-kindergarten-through-twelfth-grade (PK-12) student outcomes remains elusive (Darling-Hammond, 2010)
Epitaxial growth of visible to infra-red transparent conducting In2O3 nanodot dispersions and reversible charge storage as a Li-ion battery anode
peer-reviewedUnique bimodal distributions of single crystal epitaxially grown In2O3 nanodots on silicon are shown to have excellent IR transparency greater than 87% at IR wavelengths up to 4 mu m without sacrificing transparency in the visible region. These broadband antireflective nanodot dispersions are grown using a two-step metal deposition and oxidation by molecular beam epitaxy, and backscattered diffraction confirms a dominant (111) surface orientation. We detail the growth of a bimodal size distribution that facilitates good surface coverage (80%) while allowing a significant reduction in In2O3 refractive index. This unique dispersion offers excellent surface coverage and three-dimensional volumetric expansion compared to a thin film, and a step reduction in refractive index compared to bulk active materials or randomly porous composites, to more closely match the refractive index of an electrolyte, improving transparency. The (111) surface orientation of the nanodots, when fully ripened, allows minimum lattice mismatch strain between the In2O3 and the Si surface. This helps to circumvent potential interfacial weakening caused by volume contraction due to electrochemical reduction to lithium, or expansion during lithiation. Cycling under potentiodynamic conditions shows that the transparent anode of nanodots reversibly alloys lithium with good Coulombic efficiency, buffered by co-insertion into the silicon substrate. These properties could potentially lead to further development of similarly controlled dispersions of a range of other active materials to give transparent battery electrodes or materials capable of non-destructive in situ spectroscopic characterization during charging and discharging.ACCEPTEDpeer-reviewe
The effect of RaceRunning on cardiometabolic disease risk factors and functional mobility in young people with moderate-to-severe cerebral palsy:A feasibility study
Introduction: There is consistent evidence that people with cerebral (CP) do not engage in the recommended physical activity guidelines for the general population from a young age. Participation in moderate-to-vigorous physical activity is particularly reduced in people with CP who have moderate-to-severe disability. RaceRunning is a growing disability sport that provides an opportunity for people with moderate-to-severe disability to participate in physical activity in the community. It allows those who are unable to walk independently, to propel themselves using a RaceRunning bike, which has a breastplate for support but no pedals. The aim of this study is to examine the feasibility and acceptability of RaceRunning for young people with moderate-to-severe CP and the feasibility of conducting a definitive study of the effect of RaceRunning on cardiometabolic disease risk factors and functional mobility.
Methods and analysis: Twenty-five young people (age 5-21 yr) with CP or acquired brain injury affecting co-ordination will be included in this single arm intervention study. Participants will take part in one RaceRunning session each week for 24 weeks. Outcomes assessed at baseline, 12 and 24 weeks include body mass index, waist circumference, blood pressure, muscle strength, cardiorespiratory fitness, physical activity and sedentary behaviour, functional mobility, activity competence and psychosocial impact. Adverse events will be systematically recorded throughout the 24 weeks. Focus groups will be conducted with participants and/or parents to explore their views and experiences of taking part in RaceRunning.
Ethics and dissemination: Approval has been granted by Queen Margaret University Research Ethics Committee (REC) and the South East of Scotland REC. Results will be disseminated through peer-reviewed journals and distributed to people with CP and their families through RaceRunning and Athletic Clubs, NHS trusts, and organisations for people with disabilities
Painless loss of vision: rapid diagnosis of a central retinal artery occlusion utilizing point-of-care ultrasound
Point-of-care ultrasound (POCUS) has become an essential part of the evaluation of vision loss among emergency physicians in the emergency department (ED). It is frequently used to evaluate for vitreous hemorrhage, foreign bodies, retinal detachment, optic neuritis and posterior vitreous detachment; however, it can also be used to evaluate for a central retinal artery occlusion (CRAO). A POCUS can reveal a hyperechoic density in the optic nerve sheath just proximal to the retinal surface, and this is referred to as a retrobulbar 'spot sign' (RBSS). We present the case of an 88-year-old male that presented to our community ED with a painless loss of vision to his right eye. A POCUS revealed an RBSS of the central retinal artery and he was subsequently diagnosed with a CRAO. At his 1-month follow-up, he has regained light perception and 15% of his vision, however, remains with significant visual impairment
The Relationship Between HR Practices and Firm Performance: Examining Causal Order
Significant research attention has been devoted to examining the relationship between HR practices and firm performance, and the research support has assumed HR as the causal variable. Using data from 45 business units (with 62 data points), this study examines how measures of HR practices correlate with past, concurrent, and future operational performance measures. The results indicate that correlations with performance measures at all three times are both high and invariant, and that controlling for past or concurrent performance virtually eliminates the correlation of HR with future performance. Implications are discussed
Outcomes from the Children and Young People’s Advocacy House Consultation Event – MediaCityUK
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