5,219 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

    Far infrared CO and H2_2O emission in intermediate-mass protostars

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    Intermediate-mass young stellar objects (YSOs) provide a link to understand how feedback from shocks and UV radiation scales from low to high-mass star forming regions. Aims: Our aim is to analyze excitation of CO and H2_2O in deeply-embedded intermediate-mass YSOs and compare with low-mass and high-mass YSOs. Methods: Herschel/PACS spectral maps are analyzed for 6 YSOs with bolometric luminosities of Lbol102103L_\mathrm{bol}\sim10^2 - 10^3 LL_\odot. The maps cover spatial scales of 104\sim 10^4 AU in several CO and H2_2O lines located in the 55210\sim55-210 μ\mum range. Results: Rotational diagrams of CO show two temperature components at Trot320T_\mathrm{rot}\sim320 K and Trot700800T_\mathrm{rot}\sim700-800 K, comparable to low- and high-mass protostars probed at similar spatial scales. The diagrams for H2_2O show a single component at Trot130T_\mathrm{rot}\sim130 K, as seen in low-mass protostars, and about 100100 K lower than in high-mass protostars. Since the uncertainties in TrotT_\mathrm{rot} are of the same order as the difference between the intermediate and high-mass protostars, we cannot conclude whether the change in rotational temperature occurs at a specific luminosity, or whether the change is more gradual from low- to high-mass YSOs. Conclusions: Molecular excitation in intermediate-mass protostars is comparable to the central 10310^{3} AU of low-mass protostars and consistent within the uncertainties with the high-mass protostars probed at 31033\cdot10^{3} AU scales, suggesting similar shock conditions in all those sources.Comment: Accepted to Astronomy & Astrophysics. 4 pages, 5 figures, 3 table

    Growth and carcass quality of grazing Holstein bulls and Limousine x Holstein bulls and heifers slaughtered at 17 months of age

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    Across sexes, crossbreeding did not improve growth rate compared to HOL bulls Crossbreeding markedly improved conformation Heifers produced carcasses of acceptable fatness Fatness and lean/fat colour of pasture-fed bulls were not acceptabl

    Rotational properties of dipolar Bose-Einstein condensates confined in anisotropic harmonic potentials

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    We study the rotational properties of a dipolar Bose-Einstein condensate confined in a quasi-two- dimensional anisotropic trap, for an arbitrary orientation of the dipoles with respect to their plane of motion. Within the mean-field approximation we find that the lowest-energy state of the system depends strongly on the relative strength between the dipolar and the contact interactions, as well as on the size and the orientation of the dipoles, and the size and the orientation of the deformation of the trapping potential.Comment: 6 pages, 5 figure

    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

    Inventaire des mollusques d'eau douce en Ituri (Haut-Zaïre) : conséquences sanitaires pour l'homme et le bétail

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    Cent soixante-dix points d'abreuvement pour le bétail ont été prospectés de juin 1986 à août 1988 en Ituri (nord-est du Zaïre) afin de déterminer les principaux mollusques d'eau douce pouvant intervenir dans la transmission des trématodoses animales et humaines. Dix-neuf espèces de gastéropodes ont été rencensées. Quatre gîtes sur dix n'hébergent pas ou très peu de mollusques. Les trois espèces les plus fréquemment rencontrées sont #Lymnaea natalensis, #Biomphalaria pfeifferi(27,6 (27,6 %) et #Bulinus africanus (15,3 %). La distribution des deux premières espèces semble très homogène au niveau régional et ne permet pas l'établissement d'une relation avec le risque parasitaire (#Fasciola gigantica et #Schistosoma mansoni). Inversement, la répartition de #Bulinus africanus (et secondairement celle de #B. forskalii) correspond globalement à la distribution de #Schistosoma bovis chez les bovins. L'association de #Lymnaea natalensis et de #Bulinus africanus au sein des gîtes rend compte de l'association des infestations à #Fasciola gigantica et #Schistosoma bovis$ chez les bovins. (Résumé d'auteur

    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

    Measurement report: Atmospheric fluorescent bioaerosol concentrations measured during 18 months in a coniferous forest in the south of Sweden

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    Biological aerosol particles affect human health, are essential for microbial and gene dispersal, and have been proposed as important agents for atmospheric processes. However, the abundance and size distributions of atmospheric biological particles are largely unknown. In this study we used a laser-induced fluorescence instrument to measure fluorescent biological aerosol particle (FBAP) concentrations for 18 months (October 2020–April 2022) at a rural, forested site in Sweden. The aim of this study was to investigate FBAP number concentrations (NFBAP) over time and analyze their relationship with meteorological parameters. NFBAP was highest in summer and lowest in winter, exhibiting a ∼ 5-fold difference between these seasons. The median NFBAP was 0.0050, 0.0025, 0.0027, and 0.0126 cm−3 in fall, winter, spring, and summer, respectively, and constituted ∼ 0.1–0.5 % of the total supermicron particle number concentration. NFBAP was dominated by the smallest measured size fraction (1–3 µm), suggesting that the main portions of the biological particles measured were due to single bacterial cells, fungal spores, and bacterial agglomerates. NFBAP was significantly correlated with increasing air temperature (P&lt;0.01) in all seasons. For most of the campaign NFBAP was seen to increase with wind speed (P&lt;0.01), while the relationship with relative humidity was for most of the campaign nonsignificant (46 %) but for a large part (30 %) negative (P&lt;0.05). Our results indicate that NFBAP was highest during warm and dry conditions when wind speeds were high, suggesting that a major part of the FBAP in spring and summer was due to mechanical aerosol generation and release mechanisms. In fall, relative humidity may have been a more important factor in bioaerosol release. This is one of the longest time series of atmospheric FBAPs, which are greatly needed for estimates of bioaerosol background concentrations in comparable regions.</p

    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
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