2,420 research outputs found

    Born to yawn? Understanding yawning as a warning of the rise in cortisol levels: Randomized trial

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    Background: Yawning consistently poses a conundrum to the medical profession and neuroscientists. Despite neurological evidence such as parakinesia brachialis oscitans in stroke patients and thermo-irregulation in multiple sclerosis patients, there is considerable debate over the reasons for yawning with the mechanisms and hormonal pathways still not fully understood. Cortisol is implicated during yawning and may link many neurological disorders. Evidence was found in support of the Thompson cortisol hypothesis that proposes cortisol levels are elevated during yawning just as they tend to rise during stress and fatigue. Objectives: To investigate whether saliva cortisol levels rise during yawning and, therefore, support the Thompson cortisol hypothesis. Methods: We exposed 20 male and female volunteers aged between 18 and 53 years to conditions that provoked a yawning response in a randomized controlled trial. Saliva samples were collected at the start and again after the yawning response, or at the end of the stimuli presentations if the participant did not yawn. In addition, we collected electromyographic data of the jaw muscles to determine rest and yawning phases of neural activity. Yawning susceptibility scale, Hospital Anxiety and Depression Scale, General Health Questionnaire, and demographic and health details were also collected from each participant. A comprehensive data set allowed comparison between yawners and nonyawners, as well as between rest and yawning phases. Collecting electromyographic data from the yawning phase is novel, and we hope this will provide new information about neuromuscular activity related to cortisol levels. Exclusion criteria included chronic fatigue, diabetes, fibromyalgia, heart conditions, high blood pressure, hormone replacement therapy, multiple sclerosis, and stroke. We compared data between and within participants. Results: In the yawning group, there was a significant difference between saliva cortisol samples (t = -3.071, P = .01). Power and effect size were computed based on repeated-measures t tests for both the yawning and nonyawning groups. There was a medium effect size for the nonyawners group (r = .467) but low power (36%). Results were similar for the yawners group: medium effect size (r = .440) and low power (33%). Conclusions: There was significant evidence in support of the Thompson cortisol hypothesis that suggests cortisol levels are elevated during yawning. A further longitudinal study is planned to test neurological patients. We intend to devise a diagnostic tool based on changes in cortisol levels that may assist in the early diagnosis of neurological disorders based on the data collected. Trial Registration: International Standard Randomized Controlled Trial Number (ISRCTN): 61942768; http://www.controlled-trials.com/ISRCTN61942768/61942768 (Archived by WebCite at http://www.webcitation.org/6A75ZNYvr)

    Neutrino-driven Explosions

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    The question why and how core-collapse supernovae (SNe) explode is one of the central and most long-standing riddles of stellar astrophysics. A solution is crucial for deciphering the SN phenomenon, for predicting observable signals such as light curves and spectra, nucleosynthesis, neutrinos, and gravitational waves, for defining the role of SNe in the evolution of galaxies, and for explaining the birth conditions and properties of neutron stars (NSs) and stellar-mass black holes. Since the formation of such compact remnants releases over hundred times more energy in neutrinos than the SN in the explosion, neutrinos can be the decisive agents for powering the SN outburst. According to the standard paradigm of the neutrino-driven mechanism, the energy transfer by the intense neutrino flux to the medium behind the stagnating core-bounce shock, assisted by violent hydrodynamic mass motions (sometimes subsumed by the term "turbulence"), revives the outward shock motion and thus initiates the SN blast. Because of the weak coupling of neutrinos in the region of this energy deposition, detailed, multidimensional hydrodynamic models including neutrino transport and a wide variety of physics are needed to assess the viability of the mechanism. Owing to advanced numerical codes and increasing supercomputer power, considerable progress has been achieved in our understanding of the physical processes that have to act in concert for the success of neutrino-driven explosions. First studies begin to reveal observational implications and avenues to test the theoretical picture by data from individual SNe and SN remnants but also from population-integrated observables. While models will be further refined, a real breakthrough is expected through the next Galactic core-collapse SN, when neutrinos and gravitational waves can be used to probe the conditions deep inside the dying star. (abridged)Comment: Author version of chapter for 'Handbook of Supernovae,' edited by A. Alsabti and P. Murdin, Springer. 54 pages, 13 figure

    Mesorhizobium septentrionale sp nov and Mesorhizobium temperatum sp nov., isolated from Astragalus adsurgens growing in the northern regions of China

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    Ninety-five rhizobial strains isolated from Astragalus adsurgens growing in the northern regions of China were classified into three main groups, candidate species 1, 11 and 111, based on a polyphasic approach. Comparative analysis of full-length 16S rRNA gene sequences of representative strains showed that candidate species I and 11 were Mesorhizobium, while candidate species 111, which consisted of non-nodulating strains, was closely related to Agrobacterium tumefaciens. The phylogenetic relationships of the three candidate species and some related strains were also confirmed by the sequencing of glnA genes, which were used as an alternative chromosomal marker. The DNA-DNA relatedness was between 11.3 and 47-1 % among representative strains of candidate species I and 11 and the type strains of defined Mesorhizobium species. Candidate III had DNA relatedness of between 4(.)3 and 25(.)2 % with type strains of Agrobacterium tumefaciens and Agrobacterium rubi. Two novel species are proposed to accommodate candidate species I and 11, Mesorhizobium septentrionale sp. nov. (type strain, SIDW014(T) =CCBAU 11014(T) = HAMBI 2582(T)) and Mesorhizobium temperatum sp. nov. (type strain, SIDW018(T) = CCBAU 11018(T) =HAMBI 2583(T)), respectively. At least two distinct nodA sequences were identified among the strains. The numerically dominant nodA sequence type was most similar to that from the Mesorhizobium tianshanense type strain and was identified in strains belonging to the two novel species as well as other, as yet, undefined genome types. Host range studies indicate that the different nodA sequences correlate with different host ranges. Further comparative studies with the defined Agrobacterium species are needed to clarify the taxonomic identity of candidate species 111

    Probabilistic analysis of degradation of façade claddings using Markov chain models

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    In this study, the time-dependent stochastic degradation of three types of claddings is analysed. For this purpose, 203 fac¸ades with stone claddings(directly adhered to the substrate), 195 with adhered ceramic claddings and 220 with painted surfaces were analysed. All the fac¸ades are located in Lisbon, Portugal. Their degradation condition was assessed through an extensive field work. Based on the data gathered, Markov chains are used to predict the degradation of claddings and to understand, in some detail, how the characteristics of the claddings contribute to the overall degradation. The results show that the distance from the sea and exposure to damp are significant to the degradation of all types of cladding. The type and size of stone plates also influence the degradation of stone claddings. The exposure to wind-rain action has a high impact on the degradation of ceramic claddings. The models proposed provide useful information on the probability of failure of the claddings; these results are fundamental in the context of insurance policies and in the definition of building maintenance plans

    A Comprehensive Study of Gamma-Ray Burst Optical Emission: I. Flares and Early Shallow Decay Component

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    Well-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are compiled from the literature. By empirical fitting we identify eight possible emission components and summarize the results in a "synthetic" lightcurve. Both optical flare and early shallow-decay components are likely related to long-term central engine activities. We focus on their statistical properties in this paper. Twenty-four optical flares are obtained from 19 GRBs. The isotropic R-band energy is smaller than 1% of Eγ,isoE_{\gamma, \rm iso}. The relation between isotropic luminosities of the flares and gamma-rays follows LR,isoFLγ,iso1.11±0.27L^{\rm F}_{\rm R, iso}\propto L_{{\gamma}, \rm iso}^{1.11\pm 0.27}. Later flares tend to be wider and dimmer, i.e., wFtpF/2w^{\rm F}\sim t^{\rm F}_{\rm p}/2 and LR,isoF[tpF/(1+z)]1.15±0.15L^{\rm F}_{\rm R, iso}\propto [t^{\rm F}_{\rm p}/(1+z)]^{-1.15\pm0.15}. The detection probability of the optical flares is much smaller than that of X-ray flares. An optical shallow decay segment is observed in 39 GRBs. The relation between the break time and break luminosity is a power-law, with an index of 0.78±0.08-0.78\pm 0.08, similar to that derived from X-ray flares. The X-ray and optical breaks are usually chromatic, but a tentative correlation is found. We suggest that similar to the prompt optical emission that tracks γ\gamma-rays, the optical flares are also related to the erratic behavior of the central engine. The shallow decay component is likely related to a long-lasting spinning-down central engine or piling up of flare materials onto the blastwave. Mixing of different emission components may be the reason of the diverse chromatic afterglow behaviors.Comment: 43 pages, 13 figures, 3 tables, accepted for publication in Ap

    A Comprehensive Analysis of Fermi Gamma-Ray Burst Data. I. Spectral Components and Their Possible Physical Origins of LAT/GBM GRBs

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    We present a systematic analysis of the spectral and temporal properties of 17 GRBs co-detected by GBM and LAT on board the Fermi satellite by May 2010. We performed a time-resolved spectral analysis of all the bursts with the finest temporal resolution allowed by statistics, in order to avoid temporal smearing of different spectral components. We found that the time-resolved spectra of 14 out of 17 GRBs are best modeled with the Band function over the entire Fermi spectral range, which may suggest a common origin for emissions detected by LAT and GBM. GRB 090902B and GRB 090510 require the superposition between an MeV component and an extra power law component, with the former having a sharp cutoff above E_p. For GRB 090902B, this MeV component becomes progressively narrower as the time bin gets smaller, and can be fit with a Planck function as the time bin becomes small enough. In general, we speculate that phenomenologically there may be three elemental spectral components : (I) a Band-function component (e.g. in GRB 080916C) that extends in a wide energy range and does not narrow with reducing time bins, which may be of the non-thermal origin; (II) a quasi-thermal component (e.g. in GRB 090902B) with the spectra progressively narrowing with reducing time bins; and (III) another non-thermal power law component extending to high energies. The spectra of different bursts may be decomposed into one or more of these elemental components. We compare this sample with the BATSE sample and investigate some correlations among spectral parameters. We discuss the physical implications of the data analysis results for GRB prompt emission, including jet compositions (matter-dominated vs. Poynting-flux-dominated outflow), emission sites (internal shock, external shock or photosphere), as well as radiation mechanisms (synchrotron, synchrotron self-Compton, or thermal Compton upscattering).Comment: 61 pages, 25 figures, 3 tables. 2011 ApJ in pres

    Health-related quality of life in patients with β-thalassemia: Data from the phase 3 BELIEVE trial of luspatercept

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    BACKGROUND: Patients with transfusion-dependent (TD) β-thalassemia require long-term red blood cell transfusions (RBCTs) that lead to iron overload, impacting health-related quality of life (HRQoL). METHODS: The impact of luspatercept, a first-in-class erythroid maturation agent, versus placebo on HRQoL of patients with TD β-thalassemia was evaluated in the phase 3 BELIEVE trial. HRQoL was assessed at baseline and every 12 weeks using the 36-item Short Form Health Survey (SF-36) and Transfusion-dependent Quality of Life questionnaire (TranQol). Mean change in HRQoL was evaluated from baseline to week 48 for patients receiving luspatercept + best supportive care (BSC) and placebo + BSC and between luspatercept responders and non-responders. RESULTS: Through week 48, for both groups, mean scores on SF-36 and TranQol domains were stable over time and did not have a clinically meaningful change. At week 48, more patients who achieved clinical response (≥50% reduction in RBCT burden over 24 weeks) in the luspatercept + BSC group had improvement in SF-36 Physical Function compared with placebo + BSC (27.1% vs. 11.5%; p = .019). CONCLUSIONS: Luspatercept + BSC reduced transfusion burden while maintaining patients' HRQoL. HRQoL domain improvements from baseline through 48 weeks were also enhanced for luspatercept responders

    Impact of biodiesel fuel on cold starting of automotive direct injection diesel engines

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    The use of biodiesel fuels in diesel engines is gaining attention as a promising solution to control CO2 emissions. Great research efforts have been carried out to identify the impact of biodiesel physical and chemical properties on engine systems and processes. Most of these investigations were performed in warm conditions, but the suitability of biodiesel for starting the engine at under-zero ambient temperatures has not widely evaluated. The surface tension and the viscosity of biodiesel fuels are higher compared to those of standard diesel and, in cold conditions, these differences become critical since the injection fuel rate is largely affected and consequently the combustion process can be deteriorated. In order to improve its flow characteristics at cold temperatures and make them more suitable for low temperatures operation, additives are used in biodiesel fuels. In this paper the suitability of different biodiesel fuels, with and without additives, for cold starting of DI (direct injection) diesel engines has been evaluated. The results have shown that the engine start-ability with pure biodiesel fuels can be largely deteriorated. However, using diesel/biodiesel blends the start-ability of the engine can be recovered with the additional benefit of reducing the opacity peak of the exhaust gasesBroatch Jacobi, JA.; Tormos Martínez, BV.; Olmeda González, PC.; Novella Rosa, R. (2014). Impact of biodiesel fuel on cold starting of automotive direct injection diesel engines. Energy. 73:653-660. doi:10.1016/j.energy.2014.06.062S6536607

    A Comparative Plasmonic Study of Nanoporous and Evaporated Gold Films

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    Previously, we have reported that nanoporous gold (NPG) films prepared by a chemical dealloying method have distinctive plasmonic properties, i.e., they can simultaneously support localized and propagating surface plasmon resonance modes (l-SPR and p-SPR, respectively). In this study, the plasmonic properties of NPG are quantified through direct comparison with thermally evaporated gold (EG) films. Cyclic voltammetry and electrochemical impedance spectroscopy experiments reveal that the NPG films have 4–8.5 times more accessible surface area than EG films. Assemblies of streptavidin–latex beads generate p-SPR responses on both NPG and EG films that correlate well with the bead density obtained from scanning electron microscopy (SEM) images. A layer-by-layer assembly experiment on NPG involving biotinylated anti-avidin IgG and avidin, studied by l-SPR and SEM, shows that the l-SPR signal is directly linked to the accessibility of the interior of the NPG porosity, an adjustable experimental parameter that can be set by the dealloying condition and time
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