2,259 research outputs found

    Polarization-selective excitation of N-V centers in diamond

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    The nitrogen-vacancy (N-V) center in diamond is promising as an electron spin qubit due to its long-lived coherence and optical addressability. The ground state is a spin triplet with two levels (ms=±1m_s = \pm 1) degenerate at zero magnetic field. Polarization-selective microwave excitation is an attractive method to address the spin transitions independently, since this allows operation down to zero magnetic field. Using a resonator designed to produce circularly polarized microwaves, we have investigated the polarization selection rules of the N-V center. We first apply this technique to N-V ensembles in [100] and [111]-oriented samples. Next, we demonstrate an imaging technique, based on optical polarization dependence, that allows rapid identification of the orientations of many single N-V centers. Finally, we test the microwave polarization selection rules of individual N-V centers of known orientation

    Critical boron-doping levels for generation of dislocations in synthetic diamond

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    Defects induced by boron doping in diamond layers were studied by transmission electron microscopy. The existence of a critical boron doping level above which defects are generated is reported. This level is found to be dependent on the CH4 /H2 molar ratios and on growth directions. The critical boron concentration lied in the 6.5–17.0 X 10 20 at/cm3 range in the direction and at 3.2 X 1021 at/cm 3 for the one. Strain related effects induced by the doping are shown not to be responsible. From the location of dislocations and their Burger vectors, a model is proposed, together with their generation mechanism.6 page

    Geração de curva alométrica para avaliar as reservas de carbono em plantios de erva-mate, no sul do Brasil.

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    Este estudo foi realizado nos municípios de Machadinho e Barão de Cotegipe no Estado do Rio Grande do Sul, Brasil, durante o primeiro trimestre de 2007. Para a determinação da curva alométrica foram realizadas amostragens destrutivas de 30 árvores em áreas de produção de erva-mate, correspondentes a seis idades de cultivo: 4, 8, 10, 16, 22 e 25 anos, de forma a representar o ciclo produtivo da espécie florestal.A erva-mate é uma cultura característica da agricultura familiar da região Sul do Brasíl. Além de sua importância cultural é uma alternativa de geração de emprego, renda e de reposição florestal, com grande potencial de proporcionar serviços ambientais como o de seqüestro de carbono.Pelo estudo, o fluxo anual de carbono na biomassa aérea da erva-mate, é estimada, na média, em 20 t/CO2/ha/ ano, tendo como reserva no solo, mais de 207 tCO2/ha. A equação alométrica que mais se ajustou para estimar a biomassa total das árvores de erva-mate foi: Biomasa =-0,1255+0,8081*Idade+3,9672*Altura+3,6923*Biomassa folhas. O estudo demonstra um grande potencial de captura de CO2 no cultivo de ervamate caracterizando um serviço ambiental da atividade e suas possibilidades como um ativo financeiro na agricultura familiar da região sul do Brasil.bitstream/CNPF-2009-09/42628/1/BPD33.pdf1 CD-ROM

    P24 75. Resultados a medio plazo de la revascularización transmiocárdica con láser y células madre

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    ObjetivoAnalizar los resultados a medio plazo de la revascularización transmiocárdica con láser en combinación con células madre en pacientes con angina refractaria.MétodosDesde junio de 2007 hasta diciembre de 2009 se seleccionaron 19 pacientes (16 hombre y 3 mujeres) con enfermedad coronaria difusa y angina refractaria a tratamiento médico (clase III: 12 pacientes, clase IV: 7 pacientes). En todos ellos se realizó cirugía de revascularización transmiocárdica con láser en combinación con implantación de células madre de médula ósea autóloga.ResultadosLa edad media fue de 65 ± 8,5 años. La media de intervencionismos percutáneos por pacientes previos a la cirugía fue de 3,3 (rango 0-7). Ocho pacientes fueron intervenidos previamente de cirugía coronaria. No hubo efectos adversos asociados al procedimiento. No hubo mortalidad quirúrgica. El número medio de canales creados fue de 19, con un recuento celular por mililitro de: células totales mononuclares (1.660 x 106), CD34+ (9,8 x 106), y CD133+ (4,6 x 106). La mediana de estancia hospitalaria fue de 6 días. El seguimiento medio fue de 19 meses (rango 1-30). En el seguimiento un paciente falleció 24 meses tras la cirugía por insuficiencia cardíaca. En el último seguimiento 11 pacientes estaban en clase I, 5 en clase II y 3 en clase III.Tres pacientes requirieron nuevo cateterismo debido a empeoramiento de su angina.ConclusionesLa cirugía transmiocárdica con láser en combinación con inyección de células madre es un procedimiento seguro y clínicamente efectivo en pacientes con enfermedad coronaria difusa y angina refractaria a tratamiento médico

    Characterization of aerosol sources in León (Spain) using Positive Matrix Factorization and weather types

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    A one-year aerosol sampling campaign, between 2016 and 2017, was conducted in a suburban area of León city, Spain. An association between the Positive Matrix Factorization (PMF) results and air masses through circulation weather types was carried out, through the construction of linear models from the PM10 concentrations and its chemical composition. The aerosol sources, identified by PMF six-factor solution, were: traffic (29%), aged sea salt (26%), secondary aerosols (16%), dust (13%), marine aerosol (7%) and biomass burning (3%). Traffic and secondary factors showed the highest PM10 contribution in the hybrid cyclonic types with wind component from the first and second quadrant. Anticyclonic types with wind component from the first quadrant exhibited high values of secondary, aged sea salt and dust factors. The highest contributions of the dust factor were also associated with northerly types. The linear models built for estimating the source apportionment of PM10, from aerosol chemical composition and geostrophic flow, showed positive coefficients for: westerly flows (WF) in marine factor, southerly flows (SF) in secondary and traffic factors, and shear southerly vorticities (ZS) in dust factor. Negative dependences were observed for ZS in aged sea salt factor and for SF in dust factor. The PM10 mass concentration calculated by the linear models and by the PMF model were strongly correlated. This can be very useful to determine the contribution of a specific source to PM10 in León, only by knowing some meteorological and chemical variables.publishe

    Asociación entre urticaria crónica y cándida

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    "Fat but powerful'' paradox: association of muscle power and adiposity markers with all-cause mortality in older adults from the EXERNET multicentre study

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    Objectives: To assess the influence of muscle power and adiposity on all-cause mortality risk and to evaluate the fat but powerful'' (F+P) (or fat but fit'') paradox in older adults. Methods: A total of 2563 older adults (65 €''91 years old) from the EXERNET multicentre study were included. Adiposity (body mass index (BMI), waist circumference, body fat percentage (BF%) and fat index), allometric and relative power (sit-to-stand muscle power test) and various covariates (age, sex, hypertension, smoking status and walking and sitting times per day) were registered at baseline. All-cause mortality was recorded during a median follow-up of 8.9 years. Participants were classified into four groups: lean and powerful (L+P), F+P, lean but weak and fat and weak (F+W). Cox proportional hazard regression models and adjusted HRs were calculated. Results: According to BMI and waist circumference, all-cause mortality risk was reduced in the F+P (HR=0.55 and 0.63, p=0.044 and 0.049, respectively) and L+P (HR=0.57 and 0.58, p=0.043 and 0.025, respectively) groups. According to BF%, all-cause mortality decreased in the L+P group (HR=0.53; p=0.021), and a trend for a reduction was reported in the F+P group (HR=0.57; p=0.060). According to fat index, a survival benefit was only noted in the L+P group (HR=0.50; p=0.049). Higher levels of relative power reduced all-cause mortality risk among older people (HR=0.63 and 0.53, p=0.006 and 0.011, respectively). Conclusion: Powerful older people exhibited a reduced 9-year all-cause mortality regardless of BMI, waist circumference and BF%. Obesity according to fat index blunted the survival benefits of being powerful

    Seabed litter distribution in the high seas of the Flemish Pass area (NW Atlantic)

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    Seabed litter of the Flemish Pass area (NW Atlantic Ocean) was analysed and described using data from the EU-Spain groundfish survey (2006-2017 period). This study presents baseline information on seabed litter in this area. The Flemish Pass is located in areas beyond national jurisdiction within the Northwest Atlantic Fisheries Organization Regulatory Area Division 3L. A total of 1169 valid bottom trawl hauls were analysed (104-1478 m depth). Litter was found in 8.3% of the hauls, with mean densities of 1.4±0.2 items km–2 and 10.6±5.2 kg km–2. An increasing pattern with depth was found, the highest densities of seabed litter being identified in the deepest areas located in the Flemish Pass channel and down the northeastern flank of the Grand Bank. Fishing was found to be the main source of marine litter, and 61.9% of the hauls with litter presence showed litter included in the fisheries-related litter category. Whereas in most cases the litter was composed of small fragments of rope, in other cases it was composed of entire fishing gears such as traps. Plastics, metal and other anthropogenic litter were the next most abundant categories, accounting for 18.6%, 16.5% and 12.4% of the total, respectively.Versión del editor1,00
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