4,192 research outputs found

    Influence of Pure Dephasing on Emission Spectra from Single Photon Sources

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    We investigate the light-matter interaction of a quantum dot with the electromagnetic field in a lossy microcavity and calculate emission spectra for non-zero detuning and dephasing. It is found that dephasing shifts the intensity of the emission peaks for non-zero detuning. We investigate the characteristics of this intensity shifting effect and offer it as an explanation for the non-vanishing emission peaks at the cavity frequency found in recent experimental work.Comment: Published version, minor change

    Fractional differentiability for solutions of nonlinear elliptic equations

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    We study nonlinear elliptic equations in divergence form divA(x,Du)=divG.{\operatorname{div}}{\mathcal A}(x,Du)={\operatorname{div}}G. When A{\mathcal A} has linear growth in DuDu, and assuming that xA(x,ξ)x\mapsto{\mathcal A}(x,\xi) enjoys Bnα,qαB^\alpha_{\frac{n}\alpha, q} smoothness, local well-posedness is found in Bp,qαB^\alpha_{p,q} for certain values of p[2,nα)p\in[2,\frac{n}{\alpha}) and q[1,]q\in[1,\infty]. In the particular case A(x,ξ)=A(x)ξ{\mathcal A}(x,\xi)=A(x)\xi, G=0G=0 and ABnα,qαA\in B^\alpha_{\frac{n}\alpha,q}, 1q1\leq q\leq\infty, we obtain DuBp,qαDu\in B^\alpha_{p,q} for each p<nαp<\frac{n}\alpha. Our main tool in the proof is a more general result, that holds also if A{\mathcal A} has growth s1s-1 in DuDu, 2sn2\leq s\leq n, and asserts local well-posedness in LqL^q for each q>sq>s, provided that xA(x,ξ)x\mapsto{\mathcal A}(x,\xi) satisfies a locally uniform VMOVMO condition

    APEX-CHAMP+ high-J CO observations of low-mass young stellar objects: II. Distribution and origin of warm molecular gas

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    The origin and heating mechanisms of warm (50<T<200 K) molecular gas in low-mass young stellar objects (YSOs) are strongly debated. Both passive heating of the inner collapsing envelope by the protostellar luminosity as well as active heating by shocks and by UV associated with the outflows or accretion have been proposed. We aim to characterize the warm gas within protosteller objects, and disentangle contributions from the (inner) envelope, bipolar outflows and the quiescent cloud. High-J CO maps (12CO J=6--5 and 7--6) of the immediate surroundings (up to 10,000 AU) of eight low-mass YSOs are obtained with the CHAMP+ 650/850 GHz array receiver mounted on the APEX telescope. In addition, isotopologue observations of the 13CO J=6--5 transition and [C I] 3P_2-3P_1 line were taken. Strong quiescent narrow-line 12CO 6--5 and 7--6 emission is seen toward all protostars. In the case of HH~46 and Ced 110 IRS 4, the on-source emission originates in material heated by UV photons scattered in the outflow cavity and not just by passive heating in the inner envelope. Warm quiescent gas is also present along the outflows, heated by UV photons from shocks. Shock-heated warm gas is only detected for Class 0 flows and the more massive Class I sources such as HH~46. Outflow temperatures, estimated from the CO 6--5 and 3--2 line wings, are ~100 K, close to model predictions, with the exception of the L~1551 IRS 5 and IRAS 12496-7650, for which temperatures <50 K are found. APEX-CHAMP+ is uniquely suited to directly probe a protostar's feedback on its accreting envelope gas in terms of heating, photodissociation, and outflow dispersal by mapping 1'x1' regions in high-J CO and [C I] lines.Comment: 18 pages, accepted by A&A, A version with the figures in higher quality can be found on my website: http://www.cfa.harvard.edu/~tvankemp

    Effects of chicory roots on finishing performance and CLA and fatty acid composition in longissimus muscle of Friesian steers

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    Low profitability is believed to be the greatest hindrance profitability is believed to be the greatest hindrance for a more extensive use of dairy breed bull calves in for a more extensive use of dairy breed bull calves in organic beef production systems organic beef production systems Among certain consumers, there is an increasing interest Among certain consumers, there is an increasing interest for organic beef production for organic beef production However, there is a need for reliable information about However, there is a need for reliable information about and documentation for production parameters, methods and documentation for production parameters, methods for rearing and housing, feeding strategies etc. to be able for rearing and housing, feeding strategies etc. to be able to increase the consumption of beef meat based on dairy to increase the consumption of beef meat based on dairy calves in Denmark calves in Denmark. Specifically, we believe there will be increased focus on Specifically, we believe there will be increased focus on improving animal health and welfare and product quality in improving animal health and welfare and product quality in the steer production systems the steer production systems There will also be a wish from the society and EU to use There will also be a wish from the society and EU to use and preserve the biodiversity of the marginal grazing and preserve the biodiversity of the marginal grazing areas areas The project reported here arises from a larger project The project reported here arises from a larger project investigating the effects of grazing system (set investigating the effects of grazing system (set stocking vs. two stocking vs. two-paddock rotation) for steers and the paddock rotation) for steers and the use of bioactive crops (especially chicory) use of bioactive crops (especially chicory). Chicory is used because of the possible positive Chicory is used because of the possible positive influence on animal health, i.e., parasite control, meat influence on animal health, i.e., parasite control, meat quality and sensory quality of meat from both steers quality and sensory quality of meat from both steers and pigs (including CLA content, selenium and and pigs (including CLA content, selenium and antioxidative antioxidative status, drip loss and boar status, drip loss and boar taint/ taint/androstenone androstenone levels) levels). The overall objective of the entire project was to The overall objective of the entire project was to develop production methods/strategies that could develop production methods/strategies that could improve the quality aspects of organic meat improve the quality aspects of organic meat

    Mapping water in protostellar outflows with Herschel: PACS and HIFI observations of L1448-C

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    We investigate on the spatial and velocity distribution of H2O along the L1448 outflow, its relationship with other tracers, and its abundance variations, using maps of the o-H2O 1_{10}-1_{01} and 2_{12}-1_{01} transitions taken with the Herschel-HIFI and PACS instruments, respectively. Water emission appears clumpy, with individual peaks corresponding to shock spots along the outflow. The bulk of the 557 GHz line is confined to radial velocities in the range \pm 10-50 km/s but extended emission associated with the L1448-C extreme high velocity (EHV) jet is also detected. The H2O 1_{10}-1_{01}/CO(3-2) ratio shows strong variations as a function of velocity that likely reflect different and changing physical conditions in the gas responsible for the emissions from the two species. In the EHV jet, a low H2O/SiO abundance ratio is inferred, that could indicate molecular formation from dust free gas directly ejected from the proto-stellar wind. We derive averaged Tkin and n(H2) values of about 300-500 K and 5 10^6 cm-3 respectively, while a water abundance with respect to H2 of the order of 0.5-1 10^{-6} along the outflow is estimated. The fairly constant conditions found all along the outflow implies that evolutionary effects on the timescales of outflow propagation do not play a major role in the H2O chemistry. The results of our analysis show that the bulk of the observed H2O lines comes from post-shocked regions where the gas, after being heated to high temperatures, has been already cooled down to a few hundred K. The relatively low derived abundances, however, call for some mechanism to diminish the H2O gas in the post-shock region. Among the possible scenarios, we favor H2O photodissociation, which requires the superposition of a low velocity non-dissociative shock with a fast dissociative shock able to produce a FUV field of sufficient strength.Comment: 16 pages, 13 figures, accepted for publication on Astronomy & Astrophysic

    Transanal Irrigation for Neurogenic Bowel Disease, Low Anterior Resection Syndrome, Faecal Incontinence and Chronic Constipation: A Systematic Review

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    Transanal irrigation (TAI) has received increasing attention as a treatment option in patients with bowel dysfunction. This systematic review was conducted according to the PRISMA guidelines and evaluates the effect of TAI in neurogenic bowel dysfunction (NBD), low anterior resection syndrome (LARS), faecal incontinence (FI) and chronic constipation (CC). The primary outcome was the effect of TAI on bowel function. Secondary outcomes included details on TAI, quality of life (QoL), the discontinuation rate, adverse events, predictive factors for a successful outcome, and health economics. A systematic search for articles reporting original data on the effect of TAI on bowel function was performed, and 27 eligible studies including 1435 individuals were included. Three randomised controlled trials, one non-randomised trial, and 23 observational studies were included; 70% of the studies were assessed to be of excellent or good methodological quality. Results showed an improvement in bowel function among patients with NBD, LARS, FI, and CC with some studies showing improvement in QoL. However, discontinuation rates were high. Side effects were common, but equally prevalent among comparative treatments. No consistent predictive factors for a successful outcome were identified. Results from this review show that TAI improves bowel function and potentially QoL; however, evidence remains limited

    Water distribution in shocked regions of the NGC1333-IRAS4A protostellar outflow

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    We present the study of the H2O spatial distribution at two bright shocked regions along IRAS4A, one of the strongest H2O emitters among the Class 0 outflows. We obtained Herschel-PACS maps of the IRAS4A outflow and HIFI observations of two shocked positions. The largest HIFI beam of 38 arcsec at 557 GHz was mapped in several key water lines with different upper energy levels, to reveal possible spatial variations of the line profiles. We detect four H2O lines and CO (16-15) at the two selected positions. In addition, transitions from related outflow and envelope tracers are detected. Different gas components associated with the shock are identified in the H2O emission. In particular, at the head of the red lobe of the outflow, two distinct gas components with different excitation conditions are distinguished in the HIFI emission maps: a compact component, detected in the ground-state water lines, and a more extended one. Assuming that these two components correspond to two different temperature components observed in previous H2O and CO studies, the excitation analysis of the H2O emission suggests that the compact (about 3 arcsec) component is associated with a hot (T~1000 K) gas with densities ~(1-4)x10^5 cm^{-3}, whereas the extended one (10-17 arcsec) traces a warm (T~300-500 K) and dense gas (~(3-5)x10^7 cm^{-3}). Finally, using the CO (16-15) emission observed at R2, we estimate the H2O/H2 abundance of the warm and hot components to be (7-10)x10^{-7} and (3-7)x10^{-5}. Our data allowed us, for the first time, to resolve spatially the two temperature components previously observed with HIFI and PACS. We propose that the compact hot component may be associated with the jet that impacts the surrounding material, whereas the warm, dense, and extended component originates from the compression of the ambient gas by the propagating flow.Comment: 13 pages, 11 figures. Accepted for publication in Astronomy and Astrophysic

    Bias and temperature dependence of the 0.7 conductance anomaly in Quantum Point Contacts

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    The 0.7 (2e^2/h) conductance anomaly is studied in strongly confined, etched GaAs/GaAlAs quantum point contacts, by measuring the differential conductance as a function of source-drain and gate bias as well as a function of temperature. We investigate in detail how, for a given gate voltage, the differential conductance depends on the finite bias voltage and find a so-called self-gating effect, which we correct for. The 0.7 anomaly at zero bias is found to evolve smoothly into a conductance plateau at 0.85 (2e^2/h) at finite bias. Varying the gate voltage the transition between the 1.0 and the 0.85 (2e^2/h) plateaus occurs for definite bias voltages, which defines a gate voltage dependent energy difference Δ\Delta. This energy difference is compared with the activation temperature T_a extracted from the experimentally observed activated behavior of the 0.7 anomaly at low bias. We find \Delta = k_B T_a which lends support to the idea that the conductance anomaly is due to transmission through two conduction channels, of which the one with its subband edge \Delta below the chemical potential becomes thermally depopulated as the temperature is increased.Comment: 9 pages (RevTex) with 9 figures (some in low resolution

    Remote sensing, geographical information system and spatial analysis for schistosomiasis epidemiology and ecology in Africa

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    Beginning in 1970, the potential of remote sensing (RS) techniques, coupled with geographical information systems (GIS), to improve our understanding of the epidemiology and control of schistosomiasis in Africa, has steadily grown. In our current review, working definitions of RS, GIS and spatial analysis are given, and applications made to date with RS and GIS for the epidemiology and ecology of schistosomiasis in Africa are summarised. Progress has been made in mapping the prevalence of infection in humans and the distribution of intermediate host snails. More recently, Bayesian geostatistical modelling approaches have been utilized for predicting the prevalence and intensity of infection at different scales. However, a number of challenges remain; hence new research is needed to overcome these limitations. First, greater spatial and temporal resolution seems important to improve risk mapping and understanding of transmission dynamics at the local scale. Second, more realistic risk profiling can be achieved by taking into account information on people's socio-economic status; furthermore, future efforts should incorporate data on domestic access to clean water and adequate sanitation, as well as behavioural and educational issues. Third, high-quality data on intermediate host snail distribution should facilitate validation of infection risk maps and modelling transmission dynamics. Finally, more emphasis should be placed on risk mapping and prediction of multiple species parasitic infections in an effort to integrate disease risk mapping and to enhance the cost-effectiveness of their contro
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