4,332 research outputs found
Simple Metals at High Pressure
In this lecture we review high-pressure phase transition sequences exhibited
by simple elements, looking at the examples of the main group I, II, IV, V, and
VI elements. General trends are established by analyzing the changes in
coordination number on compression. Experimentally found phase transitions and
crystal structures are discussed with a brief description of the present
theoretical picture.Comment: 22 pages, 4 figures, lecture notes for the lecture given at the Erice
course on High-Pressure Crystallography in June 2009, Sicily, Ital
Assessing the impact of woody and agricultural biomass variability on its behaviour in torrefaction through Principal Component Analysis
The influence of biomass macromolecular composition on its behaviour in torrefaction was statistically assessed through Principal Component Analysis (PCA), both in terms of solid conversion kinetics and volatile species released, in function of the operating conditions. The experimental data obtained in the torrefaction of 14 woody and agricultural biomass samples at lab-scale was analysed. Main biomass macromolecular composition on cellulose, hemicelluloses and lignin was shown to acceptably represent biomass diversity, which can be complemented by the extractives and ash content. Similitudes were found in deciduous and coniferous wood families, respectively, while agricultural and herbaceous crops were shown as more heterogeneous, both in terms of characterization and behaviour in torrefaction. Cellulose, hemicelluloses and lignin content strongly influenced solid and volatile species yields in torrefaction, while biomass family exhibited a lower impact. Ash content in potassium, phosphorous and silicon did not show any influence on the extent of solid degradation through torrefaction. A lower variability was found in solid degradation profiles from woods, while agricultural crop behaviour was more heterogeneous. Different volatile species were released from biomass samples from the same family. Furthermore, different production profiles were found for volatile species chemically close, except for deciduous wood. These results indicate that, when modelling biomass torrefaction, solid mass loss can be represented by an exemplar of deciduous and coniferous wood, while several species would be required for the agricultural family. The variability of the volatile species release would require the consideration of several volatile species and several biomass samples per famil
Single yeast cell nanomotions correlate with cellular activity.
Living single yeast cells show a specific cellular motion at the nanometer scale with a magnitude that is proportional to the cellular activity of the cell. We characterized this cellular nanomotion pattern of nonattached single yeast cells using classical optical microscopy. The distribution of the cellular displacements over a short time period is distinct from random motion. The range and shape of such nanomotion displacement distributions change substantially according to the metabolic state of the cell. The analysis of the nanomotion frequency pattern demonstrated that single living yeast cells oscillate at relatively low frequencies of around 2 hertz. The simplicity of the technique should open the way to numerous applications among which antifungal susceptibility tests seem the most straightforward
Vortex nucleation as a case study of symmetry breaking in quantum systems
Mean-field methods are a very powerful tool for investigating weakly
interacting many-body systems in many branches of physics. In particular, they
describe with excellent accuracy trapped Bose-Einstein condensates. A generic,
but difficult question concerns the relation between the symmetry properties of
the true many-body state and its mean-field approximation. Here, we address
this question by considering, theoretically, vortex nucleation in a rotating
Bose-Einstein condensate. A slow sweep of the rotation frequency changes the
state of the system from being at rest to the one containing one vortex. Within
the mean-field framework, the jump in symmetry occurs through a turbulent phase
around a certain critical frequency. The exact many-body ground state at the
critical frequency exhibits strong correlations and entanglement. We believe
that this constitutes a paradigm example of symmetry breaking in - or change of
the order parameter of - quantum many-body systems in the course of adiabatic
evolution.Comment: Minor change
Pre-Operative Continued Oral Anticoagulation Impact on Early Outcomes after Transcatheter Aortic Valve Implantation
Considering that there is a lack of evidence and guideline-based recommendations on the best preoperative oral anticoagulation management (OAC) for transcatheter aortic valve implantation (TAVI), this cohort study aimed to evaluate bleeding, access site complications, and early safety in patients undergoing TAVI on continued OAC therapy vs no-OAC therapy. Three-hundred forty-four patients submitted to a TAVI procedure (66.3% no-OAC vs 33.7% OAC) were consecutively enrolled. Primary endpoint was defined as in-hospital VARC-2 life-threatening or disabling bleeding. Secondary endpoints were in-hospital VARC-2 major vascular complications and VARC-2 early safety at 30 days. Propensity score matching analysis was performed to reduce potential distribution bias, resulting in 2 well-balanced groups (92 patients in each arm). In the overall cohort, mean age, median EuroScore II, and STS-score were 78.7±7.6 years, 2.9% (1.7-5.9), and 2.3% (1.6-3.6), respectively. Despite being older (78 ± 8 vs 80 ± 6, p = 0.004) and having higher STS score (2.1 vs 2.6, p = 0.001), patients on OAC had similar incidence of in-hospital VARC-2 life-threatening or disabling bleeding (1.3% vs. 0.9%, p = 0.711), major vascular complications (4.8% vs 5.2%, p = 0.888), and VARC-2 early safety at 30 days (10.1% vs 12.1%, p = 0.575). No significant differences in the main outcomes were observed when propensity score matching was applied. In conclusion, the management of patients on OAC submitted to a TAVI procedure is challenging and requires balancing the risk of bleeding with the risk of thromboembolic events. The present study suggests that continued OAC was not associated with increased in-hospital VARC-2 life-threatening or disabling bleeding, major vascular complications, and VARC-2 early safety at 30 days
A Search for leptophilic Z_(l) boson at future linear colliders
We study the possible dynamics associated with leptonic charge in future
linear colliders. Leptophilic massive vector boson, Z_(l), have been
investigated through the process e^(+)e^(-) -> mu^(+)mu^(-). We have shown that
ILC and CLIC will give opportunity to observe Z_(l) with masses up to the
center of mass energy if the corresponding coupling constant g_(l) exceeds
10^(-3).Comment: 12 pages, 10 figure
Traffic-related pollution and asthma prevalence in children. Quantification of associations with nitrogen dioxide.
Ambient nitrogen dioxide is a widely available measure of traffic-related air pollution and is inconsistently associated with the prevalence of asthma symptoms in children. The use of this relationship to evaluate the health impact of policies affecting traffic management and traffic emissions is limited by the lack of a concentration-response function based on systematic review and meta-analysis of relevant studies. Using systematic methods, we identified papers containing quantitative estimates for nitrogen dioxide and the 12 month period prevalence of asthma symptoms in children in which the exposure contrast was within-community and dominated by traffic pollution. One estimate was selected from each study according to an a priori algorithm. Odds ratios were standardised to 10 μg/m(3) and summary estimates were obtained using random- and fixed-effects estimates. Eighteen studies were identified. Concentrations of nitrogen dioxide were estimated for the home address (12) and/or school (8) using a range of methods; land use regression (6), study monitors (6), dispersion modelling (4) and interpolation (2). Fourteen studies showed positive associations but only two associations were statistically significant at the 5 % level. There was moderate heterogeneity (I(2) = 32.8 %) and the random-effects estimate for the odds ratio was 1.06 (95 % CI 1.00 to 1.11). There was no evidence of small study bias. Individual studies tended to have only weak positive associations between nitrogen dioxide and asthma prevalence but the summary estimate bordered on statistical significance at the 5 % level. Although small, the potential impact on asthma prevalence could be considerable because of the high level of baseline prevalence in many cities. Whether the association is causal or indicates the effects of a correlated pollutant or other confounders, the estimate obtained by the meta-analysis would be appropriate for estimating impacts of traffic pollution on asthma prevalence
Delayed Rupture of the Right Sinus of Valsalva into the Right Atrium after Percutaneous Coronary Intervention
Rupture of the sinus of Valsalva is an extremely rare complication after percutaneous coronary intervention (PCI). Because it usually results from the retrograde extension of a dissection of the right coronary artery and may quickly spread to involve the entire aorta, it can cause life-threatening complications such as aortic dissection. If the dissection remains localized, it can resolve spontaneously in the first month. Our patient experienced a delayed rupture of the right sinus of Valsalva into the right atrium at approximately 3 months after PCI
Pulmonary Complication of Novel Influenza A (H1N1) Infection: Imaging Features in Two Patients
Novel influenza A (H1N1) virus is the pathogen of recent global outbreaks of febrile respiratory infection. We herein report the imaging findings of pulmonary complication in two patients with novel influenza A (H1N1) infection. The first patient without secondary infection showed the ill-defined ground-glass opacity nodules and patch areas of ground-glass opacities. The second patient with secondary pneumococcal pneumonia showed areas of lobar consolidation in the right middle lobe and left lower lobe and ground-glass opacities
Association of Specific IgE to Staphylococcal Superantigens with the Phenotype of Chronic Urticaria
It has been well established that bacterial superantigens lead to the induction and aggravation of chronic inflammatory skin diseases. We investigated the clinical significance of serum specific immunoglobulin E (lgE) to the staphylococcal superantigens staphylococcal enterotoxin A (SEA), staphylococcal enterotoxin B (SEB), and toxic shock syndrome toxin (TSST)-1 in patients with chronic urticaria (CU), focusing on the differences in these prevalences between aspirin-intolerant CU (AICU) and aspirin-tolerant CU (ATCU) patients. Aspirin sensitivity was confirmed by oral aspirin provocation test. There were 66 patients AICU and 117 patients ATCU in the study. Serum IgE antibodies specific for SEA, SEB, and TSST-1 were measured by the ImmunoCAP test and the patients were compared with 93 normal controls (NC). The prevalences of serum specific IgE to staphylococcal superantigens were significantly higher in CU than in NC patients (IgE to SEA, 13.7% vs. 5.4%; IgE to SEB, 12.0% vs. 4.3%; IgE to TSST-1, 18.0% vs. 6.5%; p< 0.05, respectively). The patients with specific IgE to SEA, SEB, and TSST-1 had higher serum total IgE levels and higher rates of atopy. Significant associations were noted between the prevalence of specific IgE to SEA and SEB and the HLA DQB1*0609 and DRB1*1302 alleles in the AICU group. We confirmed that a sub-population of patients with CU possesses serum IgE antibodies to SEA, SEB, and TSST-1. Particularly, the IgE immune response to TSST-1 is associated with aspirin sensitivity in CU patients
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