585 research outputs found

    Collective excitations of trapped one-dimensional dipolar quantum gases

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    We calculate the excitation modes of a 1D dipolar quantum gas confined in a harmonic trap with frequency ω0\omega_0 and predict how the frequency of the breathing n=2 mode characterizes the interaction strength evolving from the Tonks-Girardeau value ω2=2ω0\omega_2=2\omega_0 to the quasi-ordered, super-strongly interacting value ω2=5ω0\omega_2=\sqrt{5}\omega_0. Our predictions are obtained within a hydrodynamic Luttinger-Liquid theory after applying the Local Density Approximation to the equation of state for the homogeneous dipolar gas, which are in turn determined from Reptation Quantum Monte Carlo simulations. They are shown to be in quite accurate agreement with the results of a sum-rule approach. These effects can be observed in current experiments, revealing the Luttinger-liquid nature of 1D dipolar Bose gases.Comment: 5 pages, 2 EPS figures, RevTeX

    Dairy buffalo life cycle assessment (LCA) affected by a management choice: the production of wheat crop

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    Life cycle assessment (LCA) was performed in dairy buffalo farms representative of Southern Italian farming systems, similar due to several characteristics, with the exception of wheat production. This work evaluated the impacts derived from this management choice, comparing farms with wheat crop (WWC) or not (NWC). In agreement with the literature, economic allocation was chosen as a useful strategy to attribute equivalents to by-products, i.e., culled animals; the same criterion was also adopted to assign pollutants to wheat grain, limited to WWC farms. Environmental impacts in terms of Global Warming Potential (GWP, kg CO2 eq), Acidification Potential (AC, g SO2 eq), Eutrophication Potential (EU, g PO43- eq), Agricultural Land Occupation (ALO, m2 y) and Water Depletion (WD, m3) were estimated. The production of wheat crop significantly affected (p < 0.05) the Agricultural Land Occupation (ALO) category as WWC farms need adequate land. WWC farms could allow a significant reduction in eutrophication (EU) compared to NWC farms (p < 0.05)

    KamLAND Bounds on Solar Antineutrinos and neutrino transition magnetic moments

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    We investigate the possibility of detecting solar electron antineutrinos with the KamLAND experiment. These electron antineutrinos are predicted by spin-flavor oscillations at a significant rate even if this mechanism is not the leading solution to the SNP. KamLAND is sensitive to antineutrinos originated from solar 8{}^8B neutrinos. From KamLAND negative results after 145 days of data taking, we obtain model independent limits on the total flux of solar electron antineutrinos $\Phi({}^8 B)< 1.1-3.5\times 10^4 cm^{-2}\ s^{-1},morethanoneorderofmagnitudesmallerthanexistinglimits,andontheirappearanceprobability, more than one order of magnitude smaller than existing limits, and on their appearance probability P<0.15%(95antineutrinoproductionbyspinflavorprecession,thisupperboundimpliesanupperlimitontheproductoftheintrinsicneutrinomagneticmomentandthevalueofthesolarmagneticfield (95% CL). Assuming a concrete model for antineutrino production by spin-flavor precession, this upper bound implies an upper limit on the product of the intrinsic neutrino magnetic moment and the value of the solar magnetic field \mu B< 2.3\times 10^{-21}MeV95LMA MeV 95% CL (for LMA (\Delta m^2, \tan^2\theta)values).Limitsonneutrinotransitionmomentsarealsoobtained.Forrealisticvaluesofotherastrophysicalsolarparameterstheseupperlimitswouldimplythattheneutrinomagneticmomentisconstrainedtobe,inthemostconservativecase, values). Limits on neutrino transition moments are also obtained. For realistic values of other astrophysical solar parameters these upper limits would imply that the neutrino magnetic moment is constrained to be, in the most conservative case, \mu\lsim 3.9\times 10^{-12} \mu_B(95CL)forarelativelysmallfield (95% CL) for a relatively small field B= 50kG.Forhighervaluesofthemagneticfieldweobtain: kG. For higher values of the magnetic field we obtain: \mu\lsim 9.0\times 10^{-13} \mu_Bforfield for field B= 200kGand kG and \mu\lsim 2.0\times 10^{-13} \mu_Bforfield for field B= 1000$ kG at the same statistical significance.Comment: 13 pages, 2 figure

    Discerning Aggregation in Homogeneous Ensembles: A General Description of Photon Counting Spectroscopy in Diffusing Systems

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    In order to discern aggregation in solutions, we present a quantum mechanical analog of the photon statistics from fluorescent molecules diffusing through a focused beam. A generating functional is developed to fully describe the experimental physical system as well as the statistics. Histograms of the measured time delay between photon counts are fit by an analytical solution describing the static as well as diffusing regimes. To determine empirical fitting parameters, fluorescence correlation spectroscopy is used in parallel to the photon counting. For expedient analysis, we find that the distribution's deviation from a single Poisson shows a difference between two single fluor moments or a double fluor aggregate of the same total intensities. Initial studies were performed on fixed-state aggregates limited to dimerization. However preliminary results on reactive species suggest that the method can be used to characterize any aggregating system.Comment: 30 pages, 5 figure

    Phase fluctuations in superconductors: from Galilean invariant to quantum XY models

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    We analyze the corrections to the superfluid density due to phase fluctuations within both a continuum and a lattice model for ss- and d-wave superconductors. We expand the phase-only action beyond the Gaussian level and compare our results with the quantum XY model both in the quantum and in the classical regime. We find new dynamic anharmonic vertices, absent in the quantum XY model, which are responsible for the vanishing of the correction to the superfluid density at zero temperature in a continuum (Galilean invariant) model. Moreover the phase-fluctuation effects are reduced with respect to the XY model by a factor at least of order 1/(kFξ0)21/(k_F\xi_0)^2.Comment: 4 pages; shorter version, accepted for publication on Phys. Rev. B Rapid Com

    (13C)-Methacetin breath test provides evidence of subclinical liver dysfunction linked to fat storage but not lifestyle

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    Background &amp; Aims: Non-alcoholic fatty liver disease (NAFLD) is characterised by the presence of hepatic steatosis in the absence of other causes of secondary hepatic fat accumulation, and is usually associated with visceral, metabolically active obesity. However, the subclinical effects of body and liver fat accumulation on liver function are still unclear. Methods: We used orally administered (13C)-methacetin and breath test to quantify the efficiency of hepatic extraction from portal blood flow and liver microsomal function in 81 participants, in relation to presence/absence of ultrasonographic NAFLD, extent of body fat accumulation, insulin resistance, dietary models, and lifestyle. Results: NAFLD was present in 23% of participants with normal weight, and prevalence increased with body fat and insulin resistance. Fat accumulation, NAFLD, and insulin resistance were associated with decreased hepatic extraction efficiency, and liver microsomal function was impaired in moderate-to-severe NAFLD. Caloric intake, dietary models, and lifestyles had a minor role in promoting functional changes. Conclusions: The interplay between body fat accumulation, insulin resistance, and NAFLD is linked with altered hepatic extraction efficiency from blood flow and deranged microsomal function. Non-invasive diagnosis of subclinical alterations of liver function is relevant for primary and secondary prevention measures. Furthermore, the occurrence of NAFLD in lean individuals and the evidence that caloric intake, dietary models, and lifestyle played a minor role require further studies exploring the role of environmental factors in the natural history of these diseases. Lay summary: Obesity is progressively increasing worldwide and is paralleled by fat accumulation in the liver (non-alcoholic fatty liver disease [NAFLD]), the most common chronic liver disease worldwide. NAFLD can alter liver structure and function, with a variety of consequences ranging from asymptomatic and subclinical alterations to cirrhosis and cancer. (13C)-Methacetin breath test, a non-invasive diagnostic tool, can reveal early subclinical alterations of liver dynamic function in individuals with obesity and in patients with NAFLD

    Increase in number of the gap junctions between satellite neuroglial cells during lifetime: An ultrastructural study in rabbit spinal ganglia from youth to extremely advanced age

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    This study investigated quantitative aspects of the gap junctions between satellite neuroglial cells that envelope the spinal ganglion neurons in rabbits aged 1 year (young), 3.6 years (adult), 6.7 years (old), and 8.8 years (very old). Both the total number of gap junctions present in 30,000 mu m(2) of surface area occupied by perineuronal satellite cells, and the density of these junctions increased throughout life, including the extremely advanced age. By contrast, the mean length of individual gap junctions did not change with age. Thus, the junctional system which provides morphological support for the metabolic cooperation between satellite cells in rabbit spinal ganglia becomes more extensive as the age of the animal increases. These results support the hypothesis that the gap junctions between perineuronal satellite cells are involved in the spatial buffering of extracellular K(+) and in neuroprotection

    The perineuronal glial tissue of spinal ganglia : quantitative changes in the rabbit from youth to extremely advanced age

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    The volumes of the nerve cell bodies and those of the enveloping satellite cell sheaths from spinal ganglia were determined by morphometric methods applied to electron micrographs in young, adult, old and very old rabbits. The mean volume of the nerve cell bodies increased progressively with age; this is probably related to the increase with age of the body size of the rabbits studied. The mean volume of the satellite cell sheaths did not differ significantly in young, adult and old animals, but was significantly smaller in very old animals. It is extremely unlikely that this marked reduction in the volume of the satellite cell sheath is the result of a pathological process. The mean value of the volume ratio between the satellite cell sheaths and the related nerve cell bodies did not differ significantly in young and adult animals, but was significantly smaller in old and very old animals. This ratio was particularly low in very old animals. Our analysis showed that in each age group the volume of the satellite cell sheath is linearly related to the volume of the related nerve cell body. This result suggests that in rabbit spinal ganglia the quantitative relations between glial and nervous tissue are tightly controlled throughout life. It is suggested that ganglionic neurons release signals to influence and control the volume of their associated glial tissue. Since satellite cells have important support roles for the neurons they surround, it is likely that the marked reduction in the volume of perineuronal sheaths in the extremely advanced age is accompanied by a reduction of those roles, with negative consequences for neuronal activity

    A Fibre- vs. cereal grain-based diet: Which is better for horse welfare? Effects on intestinal permeability, muscle characteristics and oxidative status in horses reared for meat production

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    Horses reared for meat production are fed high amounts of cereal grains in comparison with horses raised for other purposes. Such feeding practice may lead to risk of poor welfare consequences. The aim of this study was to investigate the effects of two feeding practices on selected metabolic parameters and production aspects. Nineteen Bardigiano horses, 14.3&nbsp;±&nbsp;0.7&nbsp;months of age, were randomly assigned to two groups—one fed with high amounts of cereal grains (HCG; n&nbsp;=&nbsp;9; 43% hay plus 57% cereal grain-based pelleted feed) vs. one fed with high amounts of fibre (HFG; n&nbsp;=&nbsp;10; 70% hay plus 30% pelleted fibrous feed)—for 129&nbsp;days. At slaught on abattoir, biological and tissue samples were collected to evaluate the microbiological contamination of mesenteric lymph nodes and liver; selected meat quality traits (chemical composition and fatty acid profile of the Longissimus thoracis et lumborum muscle); and the oxidative status of the horse. A linear mixed model was used: dietary treatment and sex were fixed effects and their interaction analysed on production and metabolic parameters as dependent variables. Results showed an increased intestinal permeability in the horses fed HCG compared to HFG, according to the significant increased total mesophilic aerobic bacteria counts in mesenteric lymph nodes (p&nbsp;=&nbsp;0.04) and liver samples (p&nbsp;=&nbsp;0.05). Horses in HCG showed increased muscle pH (p&nbsp;=&nbsp;0.02), lighter muscle colour (L) (p&nbsp;=&nbsp;0.01), increased intramuscular fat concentrations (p&nbsp;=&nbsp;0.03), increased muscle glutathione peroxidase and superoxide dismutase activities (p&nbsp;=&nbsp;0.01 and p&nbsp;=&nbsp;0.03, respectively). Moreover, horses in HCG had lower muscle water holding capacity at interaction with sex (p&nbsp;=&nbsp;0.03, lower in female), lower muscle protein content (p&nbsp;=&nbsp;0.01), lower concentration of muscle PUFAs (p&nbsp;=&nbsp;0.05) and lower plasma catalase activities (p&nbsp;=&nbsp;0.05). Our results showed that feeding a high cereal grains diet can have global effects on horse physiology, and thus represents a threat for their welfare
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