3,871 research outputs found
Whole Farm Modeling of the Effect of Risk on Optimal Tillage and Nitrogen Fertilizer Intensity
nitrogen, tillage, risk, risk aversion, Crop Production/Industries, Farm Management, Production Economics, Risk and Uncertainty,
Electron-Beam Manipulation of Silicon Dopants in Graphene
The direct manipulation of individual atoms in materials using scanning probe
microscopy has been a seminal achievement of nanotechnology. Recent advances in
imaging resolution and sample stability have made scanning transmission
electron microscopy a promising alternative for single-atom manipulation of
covalently bound materials. Pioneering experiments using an atomically focused
electron beam have demonstrated the directed movement of silicon atoms over a
handful of sites within the graphene lattice. Here, we achieve a much greater
degree of control, allowing us to precisely move silicon impurities along an
extended path, circulating a single hexagon, or back and forth between the two
graphene sublattices. Even with manual operation, our manipulation rate is
already comparable to the state-of-the-art in any atomically precise technique.
We further explore the influence of electron energy on the manipulation rate,
supported by improved theoretical modeling taking into account the vibrations
of atoms near the impurities, and implement feedback to detect manipulation
events in real time. In addition to atomic-level engineering of its structure
and properties, graphene also provides an excellent platform for refining the
accuracy of quantitative models and for the development of automated
manipulation.Comment: 5 figures, 4 supporting figure
Infection after Acute Ischemic Stroke: Risk Factors, Biomarkers, and Outcome
Background. The activation of inflammatory cascades triggered by ischemic stroke may play a key role in the development of infections. Methods. Patients admitted with ischemic stroke within 24 hours were prospectively enrolled. Biomarkers of infection were measured on days 1, 3, and 5. The patients were continuously monitored for predefined infections.
Results. Patients with infection were older (OR 1.06 per year, 95% CI 1.01–1.11) and had a higher National Institute of Health Stroke Scale Score (NIHSS, OR 1.21, 95% CI 1.10–1.34), localization in the insula, and higher stroke volumes on diffusion-weighted imaging. The maximum temperature on days 1 and 3, leukocytes, interleukin-6, lipopolysaccharide-binding protein on days 1, 3, and 5, C-reactive protein on days 3 and 5, and procalcitonin on day 5 were higher and HLA-DR-expression on monocytes on days 1, 3, and 5 lower in patients with infection. Age and NIHSS predicted the development of infections. Infection was an independent predictor of poor functional outcome.
Conclusions. Severe stroke and increasing age were shown to be early predictors for infections after stroke
QCD and the Chiral Critical Point
As an extension of , consider a theory with ``'' flavors, where the
current quark masses are held in a fixed ratio as the overall scale of the
quark masses is varied. At nonzero temperature and baryon density it is
expected that in the chiral limit the chiral phase transition is of first
order. Increasing the quark mass from zero, the chiral transition becomes more
weakly first order, and can end in a chiral critical point. We show that the
only massless field at the chiral critical point is a sigma meson, with the
universality class that of the Ising model. Present day lattice simulations
indicate that is (relatively) near to the chiral critical point.Comment: 7 pages + 2 figures, BNL-GGP-
Clinical utility of a pediatric hand exoskeleton: identifying users, practicability, and acceptance, and recommendations for design improvement
BACKGROUND
Children and adolescents with upper limb impairments can experience limited bimanual performance reducing daily-life independence. We have developed a fully wearable pediatric hand exoskeleton (PEXO) to train or compensate for impaired hand function. In this study, we investigated its appropriateness, practicability, and acceptability.
METHODS
Children and adolescents aged 6-18 years with functional limitations in at least one hand due to a neurological cause were selected for this cross-sectional evaluation. We characterized participants by various clinical tests and quantified bimanual performance with the Assisting Hand Assessment (AHA). We identified children whose AHA scaled score increased by ≥ 7 points when using the hand exoskeleton and determined clinical predictors to investigate appropriateness. The time needed to don each component and the number of technical issues were recorded to evaluate practicability. For acceptability, the experiences of the patients and the therapist with PEXO were evaluated. We further noted any adverse events.
RESULTS
Eleven children (median age 11.4 years) agreed to participate, but data was available for nine participants. The median AHA scaled score was higher with PEXO (68; IQR: 59.5-83) than without (55; IQR: 37.5-80.5; p = 0.035). The Box and Block test, the Selective Control of the Upper Extremity Scale, and finger extensor muscle strength could differentiate well between those participants who improved in AHA scaled scores by ≥ 7 points and those who did not (sensitivity and specificity varied between 0.75 and 1.00). The median times needed to don the back module, the glove, and the hand module were 62, 150, and 160 s, respectively, but all participants needed assistance. The most critical failures were the robustness of the transmission system, the electronics, and the attachment system. Acceptance was generally high, particularly in participants who improved bimanual performance with PEXO. Five participants experienced some pressure points. No adverse events occurred.
CONCLUSIONS
PEXO is a safe exoskeleton that can improve bimanual hand performance in young patients with minimal hand function. PEXO receives high acceptance. We formulated recommendations to improve technical issues and the donning before such exoskeletons can be used under daily-life conditions for therapy or as an assistive device. Trial registration Not appropriate
REDUCING VENTILATOR ALARMS THROUGH DECREASED RAINOUT IN VENTILATOR CIRCUITS: A BENCH STUDY
Alarm fatigue is a significant problem in healthcare, particularly in high acuity settings such as intensive care, surgery, and emergency departments. Alarms are triggered by various devices such as anesthesia machines, ventilators, patient monitors or humidifiers. Heated humidifiers (HH) used with mechanical ventilators, while necessary to prevent other complications associated with mechanical ventilators, may cause condensation in the ventilator circuit, prompting occlusion alarms indicating a risk for the patient. Technological advances in HH circuits may reduce rainout in the circuits and therefore occlusion alarms. Bench experiments measured alarms and rainout of two commercially available humidifiers (AirLife DuoTherm™ and Fisher & Paykel MR850) and four different pediatric and adult patient breathing circuits. The tests examined condensation accumulation in the circuits after 24 hours of low-, nominal-, or high-flow rates of gas at low-, nominal-, and high-ambient temperature settings. Dual-limb designs of adult- and neonate-sized circuits underwent evaluation. Data on alarms was collected for each system. Low temperature and occlusion alarms were less common in DuoTherm vs. MR850 HH circuits (6 vs. 68 alarms, respectively). DuoTherm products accumulated significantly less rainout for both circuit sizes at all ambient temperatures. In general, the set flow rate did not dramatically affect the amount of rainout for adult and infant circuits, but low versus high ambient temperatures yielded increased rainout for all circuit types (p < 0.02). The DuoTherm HH device and patient circuits developed significantly less alarms due to rainout and low temperatures compared to those from MR850 under all the conditions tested. Such reduction in patient alarms should help reduce alarm fatigue among healthcare workers in critical care settings
Glutathione biosynthesis in Arabidopsis trichome cells
In Arabidopsis thaliana, trichome cells are specialized unicellular structures with uncertain functions. Based on earlier observations that one of the genes involved in cysteine biosynthesis (Atcys-3A) is highly expressed in trichomes, we have extended our studies in trichome cells to determine their capacity for glutathione (GSH) biosynthesis. First, we have analyzed by in situ hybridization the tissue-specific expression of the genes Atcys-3A and sat5, which encode O-acetylserine(thio)lyase (OASTL) and serine acetyltransferase (SAT), respectively, as well as gsh1 and gsh2, which encode γ-glutamylcysteine synthetase and glutathione synthetase, respectively. The four genes are highly expressed in leaf trichomes of Arabidopsis, and their mRNA accumulate to high levels. Second, we have directly measured cytoplasmic GSH concentration in intact cells by laser-scanning microscopy after labeling with monochlorobimane as a GSH-specific probe. From these measurements, cytosolic GSH concentrations of 238 ± 25, 80 ± 2, and 144 ± 19 μM were estimated for trichome, basement, and epidermal cells, respectively. Taking into account the volume of the cells measured using stereological techniques, the trichomes have a total GSH content more than 300-fold higher than the basement and epidermal cells. Third, after NaCl treatment, GSH biosynthesis is markedly decreased in trichomes. Atcys-3A, sat5, gsh1, and gsh2 mRNA levels show a decrease in transcript abundance, and [GSH](cyt) is reduced to 47 ± 5 μM. These results suggest the important physiological significance of trichome cells related to GSH biosynthesis and their possible role as a sink during detoxification processes.Dirección General de Investigación Científica y Técnica PB96-1367Junta de Andalucía CVI011
Distinct redox regulation in sub-cellular compartments in response to various stress conditions in Saccharomyces cerevisiae
Responses to many growth and stress conditions are assumed to act via changes to the cellular redox status. However, direct measurement of pH-adjusted redox state during growth and stress has never been carried out. Organellar redox state (EGSH) was measured using the fluorescent probes roGFP2 and pHluorin in Saccharomyces cerevisiae. In particular, we investigated changes in organellar redox state in response to various growth and stress conditions to better understand the relationship between redox-, oxidative- and environmental stress response systems. EGSH values of the cytosol, mitochondrial matrix and peroxisome were determined in exponential and stationary phase in various media. These values (-340 to -350 mV) were more reducing than previously reported. Interestingly, sub-cellular redox state remained unchanged when cells were challenged with stresses previously reported to affect redox homeostasis. Only hydrogen peroxide and heat stress significantly altered organellar redox state. Hydrogen peroxide stress altered the redox state of the glutathione disulfide/glutathione couple (GSSG, 2H+/2GSH) and pH. Recovery from moderate hydrogen peroxide stress was most rapid in the cytosol, followed by the mitochondrial matrix, with the peroxisome the least able to recover. Conversely, the bulk of the redox shift observed during heat stress resulted from alterations in pH and not the GSSG, 2H+/2GSH couple. This study presents the first direct measurement of pH-adjusted redox state in sub-cellular compartments during growth and stress conditions. Redox state is distinctly regulated in organelles and data presented challenge the notion that perturbation of redox state is central in the response to many stress conditions
Distinct Clinical and Laboratory Patterns of Pneumocystis jirovecii Pneumonia in Renal Transplant Recipients.
Late post-transplant Pneumocystis jirovecii pneumonia (PcP) has been reported in many renal transplant recipients (RTRs) centers using universal prophylaxis. Specific features of PcP compared to other respiratory infections in the same population are not well reported. We analyzed clinical, laboratory, administrative and radiological data of all confirmed PcP cases between January 2009 and December 2014. To identify factors specifically associated with PcP, we compared clinical and laboratory data of RTRs with non-PcP. Over the study period, 36 cases of PcP were identified. Respiratory distress was more frequent in PcP compared to non-PcP (tachypnea: 59%, 20/34 vs. 25%, 13/53, p = 0.0014; dyspnea: 70%, 23/33 vs. 44%, 24/55, p = 0.0181). In contrast, fever was less frequent in PcP compared to non-PcP pneumonia (35%, 11/31 vs. 76%, 42/55, p = 0.0002). In both cohorts, total lymphocyte count and serum sodium decreased, whereas lactate dehydrogenase (LDH) increased at diagnosis. Serum calcium increased in PcP and decreased in non-PcP. In most PcP cases (58%, 21/36), no formal indication for restart of PcP prophylaxis could be identified. Potential transmission encounters, suggestive of interhuman transmission, were found in 14/36, 39% of patients. Interhuman transmission seems to contribute importantly to PcP among RTRs. Hypercalcemia, but not elevated LDH, was associated with PcP when compared to non-PcP
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