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A focused laser can cause local optical breakdown of a gas, which leads to rapid deposition of energy into a high-temperature plasma kernel that expands and induces a complex flow. For some conditions, hot gas is rapidly ejected along the laser axis up to distances several times the kernel size, with a particularly curious feature: relatively small changes in, for example, initial pressure can cause the direction of this ejection to reverse. Detailed axisymmetric simulations of a model energy kernel in an inert gas provide a hydrodynamic description of this phenomenon, reproducing key observations in corresponding experiments, including the vortex-ring-like features that constitute the ejection. These simulations are analysed to show how changes in the early-time kernel can lead to ejection or its reversal via alteration in the relative strength and position of the vorticity produced. A corresponding semi-infinite geometry is used to isolate two mechanisms: vorticity production by the generated shock and by baroclinic torque at the kernel boundary. Dependence on the initial kernel asymmetry is quantified, as it ultimately determines whether the vorticity, upon its subsequent evolution, develops into the ring-like structure that ejects. Even simple elongation of the energy kernel alone can reverse the direction.
Nutritional therapy is a cornerstone of burns management. The optimal macronutrient intake for wound healing after burn injury has not been identified, although high-energy, high-protein diets are favoured. The present study aimed to identify the optimal macronutrient intake for burn wound healing. The geometric framework (GF) was used to analyse wound healing after a 10 % total body surface area contact burn in mice ad libitum fed one of the eleven high-energy diets, varying in macronutrient composition with protein (P5−60 %), carbohydrate (C20−75 %) and fat (F20−75 %). In the GF study, the optimal ratio for wound healing was identified as a moderate-protein, high-carbohydrate diet with a protein:carbohydrate:fat (P:C:F) ratio of 1:4:2. High carbohydrate intake was associated with lower mortality, improved body weight and a beneficial pattern of body fat reserves. Protein intake was essential to prevent weight loss and mortality, but a protein intake target of about 7 kJ/d (about 15 % of energy intake) was identified, above which no further benefit was gained. High protein intake was associated with delayed wound healing and increased liver and spleen weight. As the GF study demonstrated that an initial very high protein intake prevented mortality, a very high-protein, moderate-carbohydrate diet (P40:C42:F18) was specifically designed. The dynamic diet study was also designed to combine and validate the benefits of an initial very high protein intake for mortality, and subsequent moderate protein, high carbohydrate intake for optimal wound healing. The dynamic feeding experiment showed switching from an initial very high-protein diet to the optimal moderate-protein, high-carbohydrate diet accelerated wound healing whilst preventing mortality and liver enlargement.
The taxonomic and ecologic composition of Earth's biota has shifted dramatically through geologic time, with some clades going extinct while others diversified. Here, we derive a metric that quantifies the change in biotic composition due to extinction or origination and show that it equals the product of extinction/origination magnitude and selectivity (variation in magnitude among groups). We also define metrics that describe the extent to which a recovery (1) reinforced or reversed the effects of extinction on biotic composition and (2) changed composition in ways uncorrelated with the extinction. To demonstrate the approach, we analyzed an updated compilation of stratigraphic ranges of marine animal genera. We show that mass extinctions were not more selective than background intervals at the phylum level; rather, they tended to drive greater taxonomic change due to their higher magnitudes. Mass extinctions did not represent a separate class of events with respect to either strength of selectivity or effect. Similar observations apply to origination during recoveries from mass extinctions, and on average, extinction and origination were similarly selective and drove similar amounts of biotic change. Elevated origination during recoveries drove bursts of compositional change that varied considerably in effect. In some cases, origination partially reversed the effects of extinction, returning the biota toward the pre-extinction composition; in others, it reinforced the effects of the extinction, magnifying biotic change. Recoveries were as important as extinction events in shaping the marine biota, and their selectivity deserves systematic study alongside that of extinction.
In Canada, recreational use of cannabis was legalized in October 2018. This policy change along with recent publications evaluating the efficacy of cannabis for the medical treatment of epilepsy and media awareness about its use have increased the public interest about this agent. The Canadian League Against Epilepsy Medical Therapeutics Committee, along with a multidisciplinary group of experts and Canadian Epilepsy Alliance representatives, has developed a position statement about the use of medical cannabis for epilepsy. This article addresses the current Canadian legal framework, recent publications about its efficacy and safety profile, and our understanding of the clinical issues that should be considered when contemplating cannabis use for medical purposes.
Glacial extent mapping and dating indicate that the local last glacial maximum (LLGM) of the northeastern Tibetan Plateau occurred during mid-Marine Isotope Stage (MIS) 3. This is asynchronous with the global last glacial maximum (LGM) that occurred during MIS 2. The causes underlying this asynchronicity are the subject of ongoing debate, and paleoclimatic reconstructions are a key to advancing understanding of the climatic influence on the spatial and temporal patterns of paleoglaciation. We used multiple methods to reconstruct the equilibrium-line altitude (ELA) of the Die Shan paleo-ice cap on the northeastern Tibetan Plateau, and to infer past temperature for ice maximum positions believed to be mid-MIS 3 in age, based on regional correlation. Geomorphic ELA reconstructions combined with an energy and mass balance model yield a paleo-ELA of 4117±31 m asl (786 m lower than present) with temperature depressions of 3.8 to ~4.6°C compared to the present. This is less than the LGM reconstruction of temperature depression inferred from other climatic proxy records on the Tibetan Plateau and suggests that the LLGM glacial advance was a product of lower temperatures and slightly reduced precipitation compared to present, whereas the LGM was a more restricted advance in which much colder conditions were combined with much lower precipitation.
To determine the typical microbial bioburden (overall bacterial and multidrug-resistant organisms [MDROs]) on high-touch healthcare environmental surfaces after routine or terminal cleaning.
Prospective 2.5-year microbiological survey of large surface areas (>1,000 cm2).
MDRO contact-precaution rooms from 9 acute-care hospitals and 2 long-term care facilities in 4 states.
Samples from 166 rooms (113 routine cleaned and 53 terminal cleaned rooms).
Using a standard sponge-wipe sampling protocol, 2 composite samples were collected from each room; a third sample was collected from each Clostridium difficile room. Composite 1 included the TV remote, telephone, call button, and bed rails. Composite 2 included the room door handle, IV pole, and overbed table. Composite 3 included toileting surfaces. Total bacteria and MDROs (ie, methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci [VRE], Acinetobacter baumannii, Klebsiella pneumoniae, and C. difficile) were quantified, confirmed, and tested for drug resistance.
The mean microbial bioburden and range from routine cleaned room composites were higher (2,700 colony-forming units [CFU]/100 cm2; ≤1–130,000 CFU/100 cm2) than from terminal cleaned room composites (353 CFU/100 cm2; ≤1–4,300 CFU/100 cm2). MDROs were recovered from 34% of routine cleaned room composites (range ≤1–13,000 CFU/100 cm2) and 17% of terminal cleaned room composites (≤1–524 CFU/100 cm2). MDROs were recovered from 40% of rooms; VRE was the most common (19%).
This multicenter bioburden summary provides a first step to determining microbial bioburden on healthcare surfaces, which may help provide a basis for developing standards to evaluate cleaning and disinfection as well as a framework for studies using an evidentiary hierarchy for environmental infection control.
Cosmogenic nuclide (CN) apparent exposure dating has become a widely used method for determining the age of glacial landforms on the Tibetan Plateau with > 1200 published ages. We present the first 10Be exposure ages from the Dalijia Shan, the most northeastern formerly glaciated mountain range on the Tibetan Plateau. The moraine groups identified from field and remote sensing imagery mapping record four glacial events at 37.07 ± 3.70 to 52.96 ± 4.70 ka (MIS 3), 20.17 ± 1.79 to 26.99 ± 2.47 ka (MIS 2), 16.92 ± 1.49 to 18.76 ± 1.88 ka (MIS 2), and 11.56 ± 1.03 to 11.89 ± 1.06 ka (Younger Dryas). These ages indicate that glaciation in the northeastern Tibetan Plateau is much younger than previously thought. In addition, this record is consistent with many other regions on the Tibetan Plateau, with a local last glacial maximum during MIS 3 asynchronous with Northern Hemisphere last glacial maximum during MIS 2. The Dalijia Shan might also include an event of Younger Dryas age, but this needs to be tested in future studies.
MoO3 films with a high work function (5.5 eV), high transparency, and a wide bandgap (3.0 - 3.4 eV) are a potential candidate for the primary back contact of Cu(InGa)Se2 thin film solar cells. This may be advantageous to form ohmic contact in superstrate devices where the back contact will be deposited after the Cu(InGa)Se2 layer and MoSe2 layer doesn’t form during Cu(InGa)Se2 deposition. In addition, the MoO3 may be incorporated in a transparent back contact in tandem or bifacial cells. In this study, MoO3 films for use as a back contact for Cu(In,Ga)Se2 thin film solar cells were prepared by reactive rf sputtering with O2/(O2+Ar) = 35%. The effect of post processing on the structural properties of the deposited films were investigated using x-ray diffraction and scanning electron microscopy. Annealing resulted in crystallization of the films to the α-MoO3 phases at 400°C. Increasing the oxygen partial pressure had no significant effect on optical transmittance of the films, and bandgaps in the range of 2.6-2.9 eV and 3.1-3.4 eV were obtained for the as deposited and annealed films, respectively. Cu(In,Ga)Se2 thin film solar cells prepared using an as-deposited Mo-MoO3 back contact yielded an efficiency of >14% with VOC = 647 (mV), JSC = 28.4 (mA), and FF. = 78.1%. Cells with ITO-MoO3 back contact showed an efficiency of ∼12% with VOC = 642 (mV), JSC = 26.8 (mA), and FF. = 69.2%. The efficiency of cells with an annealed MoO3 back contact was limited to 4%, showing a blocking diode behavior in the forward bias J-V curve. This may be caused by the presence of a barrier between the valence bands of the Cu(In,Ga)Se2 and MoO3, due to the higher bandgap of the annealed MoO3 films. SEM cross section studies showed uniform coverage of the as-deposited MoO3 layer and formation of voids for the annealed MoO3 film. Structural orientation of the Cu(In,Ga)Se2 absorber layer was also altered by the MoO3 film and less-oriented films were observed for either cases.
A superior cavopulmonary connection is commonly performed before the Fontan procedure in patients with a functionally univentricular heart. Data are limited regarding associations between a prior superior cavopulmonary connection and functional and ventricular performance late after the Fontan procedure.
We compared characteristics of those with and without prior superior cavopulmonary connection among 546 subjects enrolled in the Pediatric Heart Network Fontan Cross-Sectional Study. We further compared different superior cavopulmonary connection techniques: bidirectional cavopulmonary anastomosis (n equals 229), bilateral bidirectional cavopulmonary anastomosis (n equals 39), and hemi-Fontan (n equals 114).
A prior superior cavopulmonary connection was performed in 408 subjects (75%); the proportion differed by year of Fontan surgery and centre (p-value less than 0.0001 for each). The average age at Fontan was similar, 3.5 years in those with superior cavopulmonary connection versus 3.2 years in those without (p-value equals 0.4). The type of superior cavopulmonary connection varied by site (p-value less than 0.001) and was related to the type of Fontan procedure. Exercise performance, echocardiographic variables, and predominant rhythm did not differ by superior cavopulmonary connection status or among superior cavopulmonary connection types. Using a test of interaction, findings did not vary according to an underlying diagnosis of hypoplastic left heart syndrome.
After controlling for subject and era factors, most long-term outcomes in subjects with a prior superior cavopulmonary connection did not differ substantially from those without this procedure. The type of superior cavopulmonary connection varied significantly by centre, but late outcomes were similar.
Recent Genome-Wide Association Studies (GWAS) have identified four low-penetrance ovarian cancer susceptibility loci. We hypothesized that further moderate- or low-penetrance variants exist among the subset of single-nucleotide polymorphisms (SNPs) not well tagged by the genotyping arrays used in the previous studies, which would account for some of the remaining risk. We therefore conducted a time- and cost-effective stage 1 GWAS on 342 invasive serous cases and 643 controls genotyped on pooled DNA using the high-density Illumina 1M-Duo array. We followed up 20 of the most significantly associated SNPs, which are not well tagged by the lower density arrays used by the published GWAS, and genotyping them on individual DNA. Most of the top 20 SNPs were clearly validated by individually genotyping the samples used in the pools. However, none of the 20 SNPs replicated when tested for association in a much larger stage 2 set of 4,651 cases and 6,966 controls from the Ovarian Cancer Association Consortium. Given that most of the top 20 SNPs from pooling were validated in the same samples by individual genotyping, the lack of replication is likely to be due to the relatively small sample size in our stage 1 GWAS rather than due to problems with the pooling approach. We conclude that there are unlikely to be any moderate or large effects on ovarian cancer risk untagged by less dense arrays. However, our study lacked power to make clear statements on the existence of hitherto untagged small-effect variants.
To determine whether hydrogen peroxide vapor (HPV) decontamination can reduce environmental contamination with and nosocomial transmission of Clostridium difficile.
A prospective before-after intervention study.
A hospital affected by an epidemic strain of C. difficile.
Intensive HPV decontamination of 5 high-incidence wards followed by hospital-wide decontamination of rooms vacated by patients with C. difficile-associated disease (CDAD). The preintervention period was June 2004 through March 2005, and the intervention period was June 2005 through March 2006.
Eleven (25.6%) of 43 cultures of samples collected by sponge from surfaces before HPV decontamination yielded C. difficile, compared with 0 of 37 cultures of samples obtained after HPV decontamination (P < .001). On 5 high-incidence wards, the incidence of nosocomial CDAD was significantly lower during the intervention period than during the preintervention period (1.28 vs 2.28 cases per 1,000 patient-days; P = .047). The hospital-wide CDAD incidence was lower during the intervention period than during the preintervention period (0.84 vs 1.36 cases per 1,000 patient-days; P = .26). In an analysis limited to months in which the epidemic strain was present during both the preintervention and the intervention periods, CDAD incidence was significandy lower during the intervention period than during the preintervention period (0.88 vs 1.89 cases per 1,000 patient-days; P = .047).
HPV decontamination was efficacious in eradicating C. difficile from contaminated surfaces. Further studies of the impact of HPV decontamination on nosocomial transmission of C. difficile are warranted.