1,524 research outputs found
Florida Charter Schools: Hot and Humid with Passing Storms
This report examines the history of Florida's charter school initiative, results to date, and areas where the state can improve
Effect of endurance training on lung function: A one year study
The official published version can be accessed from the link below.Objective: To identify in a follow up study airway changes occurring during the course of a sport season in healthy endurance athletes training in a Mediterranean region.
Methods: Respiratory pattern and function were analysed in 13 healthy endurance trained athletes, either during a maximal exercise test, or at rest and during recovery through respiratory manoeuvres (spirometry and closing volume tests). The exercise test was conducted on three different occasions: during basic endurance training and then during the precompetition and competitive periods.
Results: During the competitive period, a slight but non-clinically significant decrease was found in forced vital capacity (â3.5%, p = 0.0001) and an increase in slope of phase III (+25%, p = 0.0029), both at rest and after exercise. No concomitant reduction in expiratory flow rates was noticed. During maximal exercise there was a tachypnoeic shift over the course of the year (mean (SEM) breathing frequency and tidal volume were respectively 50 (2) cycles/min and 3.13 (0.09) litres during basic endurance training v 55 (3) cycles/min and 2.98 (0.10) litres during the competitive period; p<0.05).
Conclusions: This study does not provide significant evidence of lung function impairment in healthy Mediterranean athletes after one year of endurance training
Towards the noise reduction of piezoelectrical-driven synthetic jet actuators
This paper details an experimental investigation aimed at reducing the noise output of piezoelectrical-driven synthetic jet actuators without compromising peak jet velocity. Specifically, the study considers double-chamber ('back-to-back') actuators for anti-phase noise suppression and corrugated-lobed orifices as a method to enhance turbulent mixing of the jets to suppress jet noise. The study involved the design, manufacture and bench test of interchangeable actuator hardware. Hot-wire anemometry and microphone recordings were employed to acquire velocity and noise measurements respectively for each chamber configuration and orifice plate across a range of excitation frequencies and for a fixed input voltage. The data analysis indicated a 32% noise reduction (20 dBA) from operating a singlechamber, circular orifice SJA to a double-chamber, corrugated-lobed orifice SJA at the Helmholtz resonant frequency. Results also showed there was a small reduction in peak jet velocity of 7% (~3 m/s) between these two cases based on orifices of the same discharge area. Finally, the electrical-to-fluidic power conversion efficiency of the double-chamber actuator was found to be 15% across all orifice designs at the resonant frequency; approximately double the efficiency of a single-chamber actuator. This work has thus demonstrated feasible gains in noise reduction and power efficiency through synthetic jet actuator design
Deux cas d'infection humaine accidentelle par Plasmodium cynomolgi bastianellii : étude clinique et sérologique
Botulinum toxin and refractory non-neurogenic overactive detrusor
AbstractPurposeTo study the value and efficacy of botulinum toxin for treatment of cases of non-neurogenic detrusor overactivity (NNDO) that are refractory to anticholinergic drugs.Materials and methodsA systematic review of the literature, based on a keyword search of the Medline database. Selection of articles in French and English (meta-analyses, reviews, case studies and randomized, controlled clinical trials) on intradetrusor botulinum toxin injection in the management of refractory NNDO.ResultsNineteen publications (including three randomized, controlled trials) were selected. Intradetrusor injection of botulinum toxin in patients with refractory NNDO has produced promising results, with a significant improvement in physical symptoms, urodynamic parameters and quality of life. The rare side effects consist primarily of dose-dependent urine retention.ConclusionOn the basis of preliminary data, botulinum toxin appears to be a valuable therapeutic option and fills the gap between anticholinergics and surgery in the treatment of NNDO that is refractory to anticholinergic agents. Botulinum toxin has a promising future in urology but requires further scientific evaluation
Recommended from our members
Recyclable supported Pd-NHC catalytic systems for the copper free Sonogashira cross-coupling in flow
A new family of well-defined NHC-Pd complexes immobilised onto silica, alumina and titania is reported. The catalysts display activity and recyclability in the Sonogashira cross-coupling reactions under batch and continuous flow conditions. Under batch conditions the new catalytic systems were recycled up to four times with yields over 80%. These catalysts have a broad substrate scope of different aryl bromides and alkynes. The titania-supported catalysts show good conversions under continuous flow conditions at least over 8 hours on stream using MeOH as solvent.The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Programme (EC FP7) Grant Agreement n. [NMP2-SL-2012-280827]. The authors are grateful to TECSPR14-1-0045; TECNIOspring programme, the Agency for Business Competitiveness of the Government of Catalonia, ACCIĂ, the Generalitat de Catalunya (2014SGR670). and the Spanish Ministerio de EconomĂa y Competitividad (CTQ2016-75016-R) for
financial support
Rotational excitation of methylidynium (CH+) by a helium atom at high temperature
We aim to obtain accurate rate coefficients for the collisional excitation of
CH+ by He for high gas temperatures. The ab initio coupled-cluster [CCSD(T)]
approximation was used to compute the interaction potential energy. Cross
sections are then derived in the close coupling (CC) approach and rate
coefficients inferred by averaging these cross sections over a
Maxwell-Boltzmann distribution of kinetic energies. Cross sections are
calculated up to 10'000 cm^-1 for J ranging from 0 to 10. Rate coefficients are
obtained at high temperatures up to 2000 K.Comment: 4 pages, 3 figures, table with rate coefficients, accepted for
publication by A&
Spatial distribution of far-infrared rotationally excited CH<sup>+</sup> and OH emission lines in the Orion Bar photodissociation region
Context. The methylidyne cation (CH+) and hydroxyl (OH) are key molecules in the warm interstellar chemistry, but their formation and excitation mechanisms are not well understood. Their abundance and excitation are predicted to be enhanced by the presence of vibrationally excited H2 or hot gas (~500â1000 K) in photodissociation regions (PDRs) with high incident far-ultraviolet (FUV) radiation field. The excitation may also originate in dense gas (>105 cm-3) followed by nonreactive collisions with H2, H, and electrons. Previous observations of the Orion Bar suggest that the rotationally excited CH+ and OH correlate with the excited CO, which is a tracer of dense and warm gas, and that formation pumping contributes to CH+ excitation.Aims. Our goal is to examine the spatial distribution of the rotationally excited CH+ and OH emission lines in the Orion Bar to establish their physical origin and main formation and excitation mechanisms.Methods. We present spatially sampled maps of the CH+ J = 3â2 transition at 119.8 ÎŒm and the OH Î doublet at 84 ÎŒm in the Orion Bar over an area of 110âłĂ 110âł with Herschel/PACS. We compare the spatial distribution of these molecules with those of their chemical precursors, C+ , O and H2, and tracers of warm and dense gas (high-
J CO). We assess the spatial variation of the CH+ J = 2â1 velocity-resolved line profile at 1669 GHz with Herschel/HIFI spectrometer observations.Results. The OH and especially CH+ lines correlate well with the high-J CO emission and delineate the warm and dense molecular region at the edge of the Bar. While notably similar, the differences in the CH+ and OH morphologies indicate that CH+ formation and excitation are strongly related to the observed vibrationally excited H2. This, together with the observed broad CH+ line widths, indicates that formation pumping contributes to the excitation of this reactive molecular ion. Interestingly, the peak of the rotationally excited OH 84 ÎŒm emission coincides with a bright young object, proplyd 244â440, which shows that OH can be an excellent tracer of UV-irradiated dense gas.Conclusions. The spatial distribution of CH+ and OH revealed in our maps is consistent with previous modeling studies. Both formation pumping and nonreactive collisions in a UV-irradiated dense gas are important CH+ J = 3â2 excitation processes. The excitation of the OH Î doublet at 84 ÎŒm is mainly sensitive to the temperature and density
Ligurian pyroxenite-peridotite sequences (Italy) and the role of melt-rock reaction in creating enriched-MORB mantle sources
Deep melt intrusion and melt-peridotite interaction may introduce small-scale heterogeneity in the MORB mantle. These processes generate pyroxenite-bearing veined mantle that represent potential mantle sources of oceanic basalts. Natural proxies of such veined mantle are very rare and our understanding of mechanisms governing the chemical modification of mantle peridotite by MORB-type pyroxenite emplacement is very limited. We report the results of detailed spatially-controlled chemical profiles in pyroxenite-peridotite associations from the Northern Apennine ophiolitic mantle sequences (External Liguride Units, Italy), and investigate the extent and mechanism driving the local modification of peridotite by the interaction with pyroxenite-derived melt. Pyroxenites occur as cm-thick layers parallel to mantle tectonite foliation and show diffuse orthopyroxene-rich reaction rims along the pyroxenite-peridotite contact. Relative to distal unmodified peridotites, wall-rock peridotites show i) modal orthopyroxene enrichment at the expense of olivine, ii) higher Al, Ca, Si contents and slightly lower XMg, iii) Al-richer spinel and lower-XMg pyroxenes. Clinopyroxenes from wall-rock peridotites exhibit variable LREE-MREE fractionation, always resulting in SmN/NdN ratios lower than distal peridotites. From the contact with pyroxenite layers, peridotite clinopyroxenes record a REE compositional gradient up to about 15\u202fcm marked by an overall REE increase away from the pyroxenite. Beyond 15\u202fcm, and up to 23\u202fcm, the MREE and HREE content decreases while the LREEs remain at nearly constant abundances. This REE gradient is well reproduced by a two-step numerical simulation of reactive melt percolation assuming variable amounts of olivine assimilation and pyroxene crystallization. Percolative reactive flow at decreasing melt mass and rather high instantaneous melt/peridotite ratio (initial porosity of 30%), combined with high extents of fractional crystallization (i.e. relatively low Ma/Mc ratio), accounts for the overall REE enrichment in the first 15\u202fcm. Change of melt-rock reaction regime, mostly determined by the drastic decrease of porosity (\u3a6i\u202f=\u202f0.01) due to increasing crystallization rates, results in more efficient chemical buffering of the host peridotite on the HREE composition of the differentiated liquids through ion-exchange chromatographic-type processes, determining the observed increase of the LREE/HREE ratio. Emplacement of thin (cm-sized) pyroxenite veins by deep melt infiltration is able to metasomatize a much larger volume of the host peridotite. Hybrid mantle domains made by pyroxenite, metasomatized peridotite and unmodified peridotite potentially represent mantle sources of E-MORB. Results of this work stress the key role of melt-peridotite reactions in modifying the upwelling mantle prior to oceanic basalts production
Sulphur-bearing molecules in diffuse molecular clouds: new results from SOFIA/GREAT and the IRAM 30 m telescope
We have observed five sulphur-bearing molecules in foreground diffuse
molecular clouds lying along the sight-lines to five bright continuum sources.
We have used the GREAT instrument on SOFIA to observe the 1383 GHz transitions of SH towards the star-forming regions W31C,
G29.96-0.02, G34.3+0.1, W49N and W51, detecting foreground absorption towards
all five sources; and the EMIR receivers on the IRAM 30m telescope at Pico
Veleta to detect the HS 1(10)-1(01), CS J=2-1 and SO 3(2)-2(1) transitions.
In nine foreground absorption components detected towards these sources, the
inferred column densities of the four detected molecules showed relatively
constant ratios, with N(SH)/N(HS) in the range 1.1 - 3.0, N(CS)/N(HS)
in the range 0.32 - 0.61, and N(SO)/N(HS) in the range 0.08 - 0.30. The
observed SH/H ratios - in the range (0.5-2.6) - indicate
that SH (and other sulphur-bearing molecules) account for << 1% of the
gas-phase sulphur nuclei. The observed abundances of sulphur-bearing molecules,
however, greatly exceed those predicted by standard models of cold diffuse
molecular clouds, providing further evidence for the enhancement of endothermic
reaction rates by elevated temperatures or ion-neutral drift. We have
considered the observed abundance ratios in the context of shock and turbulent
dissipation region (TDR) models. Using the TDR model, we find that the
turbulent energy available at large scale in the diffuse ISM is sufficient to
explain the observed column densities of SH and CS. Standard shock and TDR
models, however, fail to reproduce the column densities of HS and SO by a
factor of about 10; more elaborate shock models - in which account is taken of
the velocity drift, relative to H, of SH molecules produced by the
dissociative recombination of HS - reduce this discrepancy to a factor
~ 3.Comment: 30 pages, accepted for publication in A&
- âŠ