11,121 research outputs found
SOME ASPECTS OF GEORADIO LOCATION IN MINERAL RESOURCES SURVEYING ENERGY
Study the possibility of developing the technical and technological
justification of georadio location of minerals according the quantity and quality
characteristics of the concrete deposits
Novel ionization reagent for the measurement of gas-phase ammonia and amines using a stand-alone atmospheric pressure gas chromatography (APGC) source.
RationaleContaminants present in ambient air or in sampling lines can interfere with the target analysis through overlapping peaks or causing a high background. This study presents a positive outcome from the unexpected presence of N-methyl-2-pyrrolidone, released from a PALL HEPA filter, in the analysis of atmospherically relevant gas-phase amines using chemical ionization mass spectrometry.MethodsGas-phase measurements were performed using a triple quadrupole mass spectrometer equipped with a modified atmospheric pressure gas chromatography (APGC) source which allows sampling of the headspace above pure amine standards. Gas-phase N-methyl-2-pyrrolidone (NMP) emitted from a PALL HEPA filter located in the inlet stream served as the ionizing agent.ResultsThis study demonstrates that some alkylamines efficiently form a [NMP + amine+H]+ cluster with NMP upon chemical ionization at atmospheric pressure. The extent of cluster formation depends largely on the proton affinity of the amine compared with that of NMP. Aromatic amines (aniline, pyridine) and diamines (putrescine) were shown not to form cluster ions with NMP.ConclusionsThe use of NMP as an ionizing agent with stand-alone APGC provided high sensitivity for ammonia and the smaller amines. The main advantages, in addition to sensitivity, are direct sampling into the APGC source and avoiding uptake on sampling lines which can be a significant problem with ammonia and amines
A Reinforcement Learning Approach to Weaning of Mechanical Ventilation in Intensive Care Units
The management of invasive mechanical ventilation, and the regulation of
sedation and analgesia during ventilation, constitutes a major part of the care
of patients admitted to intensive care units. Both prolonged dependence on
mechanical ventilation and premature extubation are associated with increased
risk of complications and higher hospital costs, but clinical opinion on the
best protocol for weaning patients off of a ventilator varies. This work aims
to develop a decision support tool that uses available patient information to
predict time-to-extubation readiness and to recommend a personalized regime of
sedation dosage and ventilator support. To this end, we use off-policy
reinforcement learning algorithms to determine the best action at a given
patient state from sub-optimal historical ICU data. We compare treatment
policies from fitted Q-iteration with extremely randomized trees and with
feedforward neural networks, and demonstrate that the policies learnt show
promise in recommending weaning protocols with improved outcomes, in terms of
minimizing rates of reintubation and regulating physiological stability
ALFALFA HI Data Stacking III. Comparison of environmental trends in HI gas mass fraction and specific star formation rate
It is well known that both the star formation rate and the cold gas content
of a galaxy depend on the local density out to distances of a few Megaparsecs.
In this paper, we compare the environmental density dependence of the atomic
gas mass fractions of nearby galaxies with the density dependence of their
central and global specific star formation rates. We stack HI line spectra
extracted from the Arecibo Legacy Fast ALFA survey centered on galaxies with UV
imaging from GALEX and optical imaging/spectroscopy from SDSS. We use these
stacked spectra to evaluate the mean atomic gas mass fraction of galaxies in
bins of stellar mass and local density. For galaxies with stellar masses less
than 10^10.5 M_sun, the decline in mean atomic gas mass fraction with density
is stronger than the decline in mean global and central specific star formation
rate. The same conclusion does not hold for more massive galaxies. We interpret
our results as evidence for ram-pressure stripping of atomic gas from the outer
disks of low mass satellite galaxies. We compare our results with the
semi-analytic recipes of Guo et al. (2011) implemented on the Millennium II
simulation. These models assume that only the diffuse gas surrounding satellite
galaxies is stripped, a process that is often termed "strangulation". We show
that these models predict relative trends in atomic gas and star formation that
are in disagreement with observations. We use mock catalogues generated from
the simulation to predict the halo masses of the HI-deficient galaxies in our
sample. We conclude that ram-pressure stripping is likely to become effective
in dark matter halos with masses greater than 10^13 M_sun.Comment: 12 pages, 10 figures. Accepted for publication in MNRA
A Transformative Experience for Occupational Therapy Students in a Simulated Learning Environment
Simulation is being integrated into nursing and medical curriculum nationally and it is well integrated into the Nursing program at Dominican University of California, However, use of simulation in allied health professionals is only an emerging practice. The aim of this program is to integrate simulation into the OT curriculum in order to facilitate the development of therapy foundation skill
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Long-term balancing selection drives evolution of immunity genes in Capsella.
Genetic drift is expected to remove polymorphism from populations over long periods of time, with the rate of polymorphism loss being accelerated when species experience strong reductions in population size. Adaptive forces that maintain genetic variation in populations, or balancing selection, might counteract this process. To understand the extent to which natural selection can drive the retention of genetic diversity, we document genomic variability after two parallel species-wide bottlenecks in the genus Capsella. We find that ancestral variation preferentially persists at immunity related loci, and that the same collection of alleles has been maintained in different lineages that have been separated for several million years. By reconstructing the evolution of the disease-related locus MLO2b, we find that divergence between ancient haplotypes can be obscured by referenced based re-sequencing methods, and that trans-specific alleles can encode substantially diverged protein sequences. Our data point to long-term balancing selection as an important factor shaping the genetics of immune systems in plants and as the predominant driver of genomic variability after a population bottleneck
Nanosecond Pulse Electric Field Activated-Platelet Rich Plasma Enhances the Return of Blood Flow to Large and Ischemic Wounds in a Rabbit Model
Platelet-rich plasma is a therapeutic strategy used for accelerating wound healing of a wide range of tissues through the release of platelet growth factors. Here, we describe a nonchemical, safe method for preparing platelet-rich plasma using nanosecond-pulsed electric fields (nsPEFs) and investigated the effect of this platelet-rich plasma on reperfusion of blood in large skin flap or ischemic hind limb wounds in New Zealand White rabbits. Laser Doppler images of blood flow to the dorsal surface of skin flap wounds or to ischemic hind limb wounds were obtained from wounds treated with 0.9% saline or nanosecond-pulsed electric field prepared platelet-rich plasma (nsPRP). Reperfusion in the skin flap wounds was greater in the nsPRP-treated wounds than in the wounds treated with saline on postoperative days 3 (P \u3c 0.001) and 21 (P \u3c 0.03). Reperfusion in the ischemic hind-limb treated with nsPRP was greater than in the saline-treated limb on post-operative Day 3 (P \u3c 0.001), post-operative week 1 (P \u3c 0.025) and post-operative week 4 (P \u3c 0.015). In the hind limb ischemic tissue, the number of endothelial cells, collagen, and cells containing vascular endothelial growth factor (VEGF) was greater in the nsPRP-treated tissue. These results demonstrate that nsPRP improves blood flow in large surgical skin wounds and in ischemic wounds
An Evaluation of Three Nutrition Labeling Formats for Restaurant Menus
This study evaluated three menu nutrition labeling formats: calorie only information, a healthy symbol, and a nutrient list. Daily sales data for a table-service restaurant located on a university campus were recorded during a four-week period from January to February 2013 to examine changes in average nutritional content of the entrees purchased by customers when different nutrition labels were provided. A survey was conducted to assess the customers’ use of nutrition labels, their preferences among the three labeling formats, their entree selections, their cognitive beliefs with regard to healthy eating, and their demographic characteristics. A total of 173 questionnaires were returned and included in data analysis. Analysis of Variance (ANOVA) and regression analyses were performed using SAS. The results showed that favorable attitudes toward healthy eating and the use of nutrition labels were both significantly associated with healthier entrée selections. Age and diet status had some effects on the respondent’s use of nutrition labels. The calorie only information format was the most effective in reducing calories contained in the entrees sold, and the nutrient list was most effective in reducing fat and saturated fat content of the entrees sold. The healthy symbol was the least effective format, but interestingly enough, was most preferred by respondents. The findings provide support for future research and offer implications for policy makers, public health professionals, and foodservice operations
Latest results from the PHOBOS experiment
Over the past years PHOBOS has continued to analyze the large datasets
obtained from the first five runs of the Relativistic Heavy Ion Collider (RHIC)
at Brookhaven National Laboratory. The two main analysis streams have been
pursued. The first one aims to obtain a broad and systematic survey of global
properties of particle production in heavy ion collisions. The second class
includes the study of fluctuations and correlations in particle production.
Both type of studies have been performed for a variety of the collision
systems, covering a wide range in collision energy and centrality. The uniquely
large angular coverage of the PHOBOS detector and its ability to measure
charged particles down to very low transverse momentum is exploited. The latest
physics results from PHOBOS, as presented at Quark Matter 2008 Conference, are
contained in this report.Comment: 9 pages, 9 figures, presented at the 20th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions, "Quark Matter 2008", Jaipur,
India, Feb.4-10, 200
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