8,355 research outputs found

    Pedometers to enhance physical activity in COPD: a randomised controlled trial

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    Physical inactivity is a cardinal feature of chronic obstructive pulmonary disease (COPD), and is associated with increased morbidity and mortality. Pedometers, which have been used in healthy populations, might also increase physical activity in patients with COPD. COPD patients taking part in a 3-month individualised programme to promote an increase in their daily physical activity were randomised to either a standard programme of physical activity encouragement alone, or a pedometer-based programme. Assessments were performed by investigators blinded to treatment allocation. Change in average 1-week daily step count, 6-min walking distance (6MWD), modified Medical Research Council scale, St George’s respiratory questionnaire (SGRQ) and COPD assessment test (CAT) were compared between groups. 102 patients were recruited, of whom 97 completed the programme (pedometer group: n=50; control group: n=47); 60.8% were male with a mean±sd age of 68.7±8.5 years, and forced expiratory volume in 1 s (FEV1) 66.1±19.4% and FEV1/forced vital capacity 55.2±9.5%. Both groups had comparable characteristics at baseline. The pedometer group had significantly greater improvements in: physical activity 3080±3254 steps·day−1 versus 138.3±1950 steps·day−1 (p<0.001); SGRQ −8.8±12.2 versus −3.8±10.9 (p=0.01); CAT score −3.5±5.5 versus −0.6±6.6 (p=0.001); and 6MWD 12.4±34.6 versus −0.7±24.4 m (p=0.02) than patients receiving activity encouragement only. A simple physical activity enhancement programme using pedometers can effectively improve physical activity level and quality of life in COPD patients

    Interlayer-confined Cu(II) complex as an efficient and long-lasting catalyst for oxidation of H2s on montmorillonite

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    Removal of highly toxic H2S for pollution control and operational safety is a pressing need. For this purpose, a montmorillonite intercalated with Cu(II)-phenanthroline complex [Cu[(Phen)(H2O)2]2+ (Mt-CuPhen) was prepared to capture gaseous H2S under mild conditions. This hybrid material was simple to obtain and demonstrated an outstanding ability to entrap H2S at room temperature, retaining high efficiency for a very long time (up to 36.8 g of S/100 g Mt-CuPhen after 3 months of exposure). Sorbent and H2S uptake were investigated by elemental analysis, X-ray powder diffraction measurements, diffuse reflectance (DR) UV\u2013Vis and infrared spectroscopy, thermal analysis and evolved gas mass spectrometry, scanning electron microscopy equipped with energy-dispersive X-ray spectrometer, and X-ray absorption spectroscopy. The H2S capture was studied over time and a mechanism of action was proposed. The entrapping involves a catalytic mechanism in which [Cu[(Phen)(H2O)2]2+ acts as catalyst for H2S oxidation to S0 by atmospheric oxygen. The low cost and the long-lasting performance for H2S removal render Mt-CuPhen an extremely appealing trap for H2S removal and a promising material for many technological applications

    Bounded solutions of fermions in the background of mixed vector-scalar P\"{o}schl-Teller-like potentials

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    The problem of a fermion subject to a convenient mixing of vector and scalar potentials in a two-dimensional space-time is mapped into a Sturm-Liouville problem. For a specific case which gives rise to an exactly solvable effective modified P\"{o}schl-Teller potential in the Sturm-Liouville problem, bound-state solutions are found. The behaviour of the upper and lower components of the Dirac spinor is discussed in detail and some unusual results are revealed. The Dirac delta potential as a limit of the modified P% \"{o}schl-Teller potential is also discussed. The problem is also shown to be mapped into that of massless fermions subject to classical topological scalar and pseudoscalar potentials.Comment: 10 pages, 1 figur

    The LISA PathFinder DMU and Radiation Monitor

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    The LISA PathFinder DMU (Data Management Unit) flight model was formally accepted by ESA and ASD on 11 February 2010, after all hardware and software tests had been successfully completed. The diagnostics items are scheduled to be delivered by the end of 2010. In this paper we review the requirements and performance of this instrumentation, specially focusing on the Radiation Monitor and the DMU, as well as the status of their programmed use during mission operations, on which work is ongoing at the time of writing.Comment: 11 pages, 7 figures, prepared for the Proceedings of the 8th International LISA Symposium, Classical and Quantum Gravit

    Temperature Effects in the Composition of Metal Halide Perovskite thin Films

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    Metal halide perovskites have shown to be a structure with great promise as an efficient photovoltaic, but at the same time it is affected by instability problems that degrade their performance. Degradation mechanisms vary with temperature, moisture, oxidation, and energy conversion during light exposure. We study performance loss due to temperature by probing diffusion of elemental composition across the thickness of films produced by spin coating and for temperatures ranging from 20 to 200°C. X-ray reflectivity was used to identify the electron density, composition, and quality of the films, aided with X-ray fluorescence and X-ray photoelectron spectroscopy studies to obtain information about degradation of the organic phase of the films

    Energy System Planning towards Renewable Power System: Energy Matrix Change in Cuba by 2030

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    Since 2013, the biggest Caribbean island, Cuba, has been undertaking an energy matrix change. There is a strong political intention to replace fossil fuels by renewable energy and improve efficiency and security of the national energy system. By 2030, 24% of electric power shall be produced from renewable sources. Transition from centralized fossil fuel fired power system towards distributed renewable generation based system requires changes to conventional energy planning and system design procedures as well as physical structures of the national energy system. This paper introduces three analysis axis: Scenario building for future supply-demand balance, scenario for a 100% renewable energy system for Cuba, and a roadmap from existing power system to the system with high share of distributed renewable generation. This work is a part of European Union funded Erasmus+ project "Capacity Building for Renewable Energy Planning in Cuban Higher Education Institutions", CRECE.<br /

    Lepton Flavor Violation in the Two Higgs Doublet Model type III

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    We consider the Two Higgs Doublet Model (2HDM) of type III which leads to Flavour Changing Neutral Currents (FCNC) at tree level in the leptonic sector. In the framework of this model we can have, in principle, two situations: the case (a) when both doublets acquire a vacuum expectation value different from zero and the case (b) when only one of them is not zero. In addition, we show that we can make two types of rotations for the flavor mixing matrices which generates four types of lagrangians, with the rotation of type I we recover the case (b) from the case (a) in the limit tanβ\tan \beta \to \infty , and with the rotation of type II we obtain the case (b) from (a) in the limit tanβ0.\tan \beta \to 0. Moreover, two of the four possible lagrangians correspond to the models of types I and II plus Flavor Changing (FC) interactions. The analitical expressions of the partial lepton number violating widths Γ(μeee)\Gamma (\mu \to eee) and Γ(μeγ)\Gamma (\mu \to e\gamma) are derived for the cases (a) and (b) and both types of rotations. In all cases these widths go asymptotically to zero in the decoupling limit for all Higgses. We present from our analysis upper bounds for the flavour changing transition μe,\mu \to e, and we show that such bounds are sensitive to the VEV structure and the type of rotation utilized.Comment: 7 pages RevTeX4, 4 figures postscript, new section added and some new reference

    Fermented Goat’s Milk Consumption Improves Duodenal Expression of Iron Homeostasis Genes during Anemia Recovery

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    Despite the crucial roles of duodenal cytochrome b (Dcytb), divalent metal transporter 1 (DMT1), ferritin light chain (Ftl1), ferroportin 1 (FPN1), transferrin receptor 1 (TfR1), and hepcidin antimicrobial peptide (Hamp) in Fe metabolism, no studies have investigated the modulations of these genes during Fe repletion with fermented milks. Analysis included Fe status markers and gene and protein expression in enterocytes of control and anemic animals fed fermented milks. Fermented goat’s milk up-regulated enterocyte Dcytb, DMT1, FPN1, and Ftl1 and down-regulated TfR1 and Hamp gene expression in control and anemic animals. Anemia decreased Dcytb, DMT1, and Ftl1 in animals fed fermented cow’s milk and up-regulated TfR1 and Hamp expression. Fe overload down-regulated Dcytb and TfR1 in animals fed fermented cow’s milk and up-regulated DMT1 and FPN1 gene expression. Fermented goat’s milk increased expression of duodenal Dcytb, DMT1, and FPN1 and decreased Hamp and TfR1, improving Fe metabolism during anemia recovery

    Photovoltaic LiNbO3particles: Applications to Biomedicine/Biophotonics

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    Recently, a novel method to trap and pattern ensembles of nanoparticles has been proposed and tested. It relies on the photovoltaic (PV) properties of certain ferroelectric crystals such as LiNbO3 [1,2]. These crystals, when suitably doped, develop very high electric fields in response to illumination with light of suitable wavelength. The PV effect lies in the asymmetrical excitation of electrons giving rise to PV currents and associated space-charge fields (photorefractive effect). The field generated in the bulk of the sample propagates to the surrounding medium as evanescent fields. When dielectric or metal nanoparticles are deposited on the surface of the sample the evanescent fields give rise to either electrophoretic or dielectrophoretic forces, depending on the charge state of the particles, that induce the trapping and patterning effects [3,4]. The purpose of this work has been to explore the effects of such PV fields in the biology and biomedical areas. A first work was able to show the necrotic effects induced by such fields on He-La tumour cells grown on the surface of an illuminated iron-doped LiNbO3 crystal [5]. In principle, it is conceived that LiNbO3 nanoparticles may be advantageously used for such biomedical purposes considering the possibility of such nanoparticles being incorporated into the cells. Previous experiments using microparticles have been performed [5] with similar results to those achieved with the substrate. Therefore, the purpose of this work has been to fabricate and characterize the LiNbO3 nanoparticles and assess their necrotic effects when they are incorporated on a culture of tumour cells. Two different preparation methods have been used: 1) mechanical grinding from crystals, and 2) bottom-up sol-gel chemical synthesis from metal-ethoxide precursors. This later method leads to a more uniform size distribution of smaller particles (down to around 50 nm). Fig. 1(a) and 1(b) shows SEM images of the nanoparticles obtained with both method. An ad hoc software taking into account the physical properties of the crystal, particullarly donor and aceptor concentrations has been developped in order to estimate the electric field generated in noparticles. In a first stage simulations of the electric current of nanoparticles, in a conductive media, due to the PV effect have been carried out by MonteCarlo simulations using the Kutharev 1-centre transport model equations [6] . Special attention has been paid to the dependence on particle size and [Fe2+]/[Fe3+]. First results on cubic particles shows large dispersion for small sizes due to the random number of donors and its effective concentration (Fig 2). The necrotic (toxicity) effect of nanoparticles incorporated into a tumour cell culture subjected to 30 min. illumination with a blue LED is shown in Fig.3. For each type of nanoparticle the percent of cell survival in dark and illumination conditions has been plot as a function of the particle dilution factor. Fig. 1a corresponds to mechanical grinding particles whereas 1b and 1c refer to chemically synthesized particles with two oxidation states. The light effect is larger with mechanical grinding nanoparticles, but dark toxicity is also higher. For chemically synthesized nanoparticles dark toxicity is low but only in oxidized samples, where the PV effect is known to be larger, the light effect is appreciable. These preliminary results demonstrate that Fe:LiNbO· nanoparticles have a biological damaging effect on cells, although there are many points that should be clarified and much space for PV nanoparticles optimization. In particular, it appears necessary to determine the fraction of nanoparticles that become incorporated into the cells and the possible existence of threshold size effects. This work has been supported by MINECO under grant MAT2011-28379-C03

    B fields in OB stars (BOB): on the detection of weak magnetic fields in the two early B-type stars beta CMa and epsilon CMa

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    Within the context of the "B fields in OB stars (BOB)" collaboration, we used the HARPSpol spectropolarimeter to observe the early B-type stars beta CMa (HD44743; B1 II/III) and epsilon CMa (HD52089; B1.5 II). For both stars, we consistently detected the signature of a weak (<30 G in absolute value) longitudinal magnetic field. We determined the physical parameters of both stars and characterise their X-ray spectrum. For beta CMa, our mode identification analysis led to determining a rotation period of 13.6+/-1.2 days and of an inclination angle of the rotation axis of 57.6+/-1.7 degrees, with respect to the line of sight. On the basis of these measurements and assuming a dipolar field geometry, we derived a best fitting obliquity of ~22 degrees and a dipolar magnetic field strength (Bd) of ~100 G (60<Bd<230 G within 1 sigma), below what is typically found for other magnetic massive stars. For epsilon CMa we could only determine a lower limit on the dipolar magnetic field strength of 13 G. For this star, we determine that the rotation period ranges between 1.3 and 24 days. Both stars are expected to have a dynamical magnetosphere. We also conclude that both stars are most likely core hydrogen burning and that they have spent more than 2/3 of their main sequence lifetime. A histogram of the distribution of the dipolar magnetic field strength for the magnetic massive stars known to date does not show the magnetic field "desert" observed instead for intermediate-mass stars. The biases involved in the detection of (weak) magnetic fields in massive stars with the currently available instrumentation and techniques imply that weak fields might be more common than currently observed. Our results show that, if present, even relatively weak magnetic fields are detectable in massive stars and that more observational effort is probably still needed to properly access the magnetic field incidence.Comment: Accepted for publication on A&A. The astroph abstract has been shortened compared to that of the pdf fil
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