519 research outputs found

    Dielectric and conductivity relaxation in mixtures of glycerol with LiCl

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    We report a thorough dielectric characterization of the alpha relaxation of glass forming glycerol with varying additions of LiCl. Nine salt concentrations from 0.1 - 20 mol% are investigated in a frequency range of 20 Hz - 3 GHz and analyzed in the dielectric loss and modulus representation. Information on the dc conductivity, the dielectric relaxation time (from the loss) and the conductivity relaxation time (from the modulus) is provided. Overall, with increasing ion concentration, a transition from reorientationally to translationally dominated behavior is observed and the translational ion dynamics and the dipolar reorientational dynamics become successively coupled. This gives rise to the prospect that by adding ions to dipolar glass formers, dielectric spectroscopy may directly couple to the translational degrees of freedom determining the glass transition, even in frequency regimes where usually strong decoupling is observed.Comment: 8 pages, 7 figure

    Motional Squashed States

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    We show that by using a feedback loop it is possible to reduce the fluctuations in one quadrature of the vibrational degree of freedom of a trapped ion below the quantum limit. The stationary state is not a proper squeezed state, but rather a ``squashed'' state, since the uncertainty in the orthogonal quadrature, which is larger than the standard quantum limit, is unaffected by the feedback action.Comment: 8 pages, 2 figures, to appear in the special Issue "Quantum Correlations and Fluctuations" of J. Opt.

    Phase space geometry and slow dynamics

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    We describe a non-Arrhenius mechanism for slowing down of dynamics that is inherent to the high dimensionality of the phase space. We show that such a mechanism is at work both in a family of mean-field spin-glass models without any domain structure and in the case of ferromagnetic domain growth. The marginality of spin-glass dynamics, as well as the existence of a `quasi equilibrium regime' can be understood within this scenario. We discuss the question of ergodicity in an out-of equilibrium situation.Comment: 23 pages, ReVTeX3.0, 6 uuencoded postscript figures appende

    Generalized stochastic Schroedinger equations for state vector collapse

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    A number of authors have proposed stochastic versions of the Schr\"odinger equation, either as effective evolution equations for open quantum systems or as alternative theories with an intrinsic collapse mechanism. We discuss here two directions for generalization of these equations. First, we study a general class of norm preserving stochastic evolution equations, and show that even after making several specializations, there is an infinity of possible stochastic Schr\"odinger equations for which state vector collapse is provable. Second, we explore the problem of formulating a relativistic stochastic Schr\"odinger equation, using a manifestly covariant equation for a quantum field system based on the interaction picture of Tomonaga and Schwinger. The stochastic noise term in this equation can couple to any local scalar density that commutes with the interaction energy density, and leads to collapse onto spatially localized eigenstates. However, as found in a similar model by Pearle, the equation predicts an infinite rate of energy nonconservation proportional to δ3(0)\delta^3(\vec 0), arising from the local double commutator in the drift term.Comment: 24 pages Plain TeX. Minor changes, some new references. To appear in Journal of Physics

    EVALUATION OF THE GROUNDWATER QUALITY IN A CLOSED INDUSTRIAL LANDFILL

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    The study parameters: pH, conductivity, salinity, Total Dissolved Solids (TDS), Turbidity, Total Suspended Solids (TSS) and Chemical Oxygen Demand (COD) of groundwater in a closed industrial landfill, subject to the waste discharges of city of Bacau (East Romania), shows that the water quality of the different sampling points is variable. This difference is noted at the level of conductivity, TDS, turbidity, TSS and COD. These differences, however parameters are substantially higher compared the value of the legislation in groundwater Romania. Salinity remains relatively high at the point of sample P1 (0.7). The pH values are comprising in the range of reference values (6.5 to 7.4). The results also showed very strong correlations (r> 0.8) between Conductivity-Salinity, Conductivity -TDS, Salinity, TDS, Turbidity.-TSS, COD and TSS-Turbidity-COD. The strong correlation (0.5 0.8) were noted between Turbidity- Conductivity, Turbidity-Salinity, Turbidity, TDS, TSS conductivity, TSS-Salinity, TSS, TDS, COD, conductivity, salinity, COD, COD-TDS. Principal Component Analysis (PCA) also highlighted groundwater mineralization events of this landfill and possible pollution by organic matter

    EVALUATION OF THE GROUNDWATER QUALITY IN A CLOSED INDUSTRIAL LANDFILL

    Get PDF
    The study parameters: pH, conductivity, salinity, Total Dissolved Solids (TDS), Turbidity, Total Suspended Solids (TSS) and Chemical Oxygen Demand (COD) of groundwater in a closed industrial landfill, subject to the waste discharges of city of Bacau (East Romania), shows that the water quality of the different sampling points is variable. This difference is noted at the level of conductivity, TDS, turbidity, TSS and COD. These differences, however parameters are substantially higher compared the value of the legislation in groundwater Romania. Salinity remains relatively high at the point of sample P1 (0.7). The pH values are comprising in the range of reference values (6.5 to 7.4). The results also showed very strong correlations (r> 0.8) between Conductivity-Salinity, Conductivity -TDS, Salinity, TDS, Turbidity.-TSS, COD and TSS-Turbidity-COD. The strong correlation (0.5 0.8) were noted between Turbidity- Conductivity, Turbidity-Salinity, Turbidity, TDS, TSS conductivity, TSS-Salinity, TSS, TDS, COD, conductivity, salinity, COD, COD-TDS. Principal Component Analysis (PCA) also highlighted groundwater mineralization events of this landfill and possible pollution by organic matter

    Suboptimal infant and young child feeding practices in rural Boucle du Mouhoun, Burkina Faso: Findings from a cross-sectional population-based survey.

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    INTRODUCTION: In Burkina Faso in 2016, 27% and 8% of children under-5 were estimated to suffer from stunting and wasting respectively. Here, we report on infant and young child feeding (IYCF) practices in rural areas of the Boucle du Mouhoun region. MATERIALS AND METHODS: A cross-sectional population-based survey was performed in 2017 in a representative sample of mothers of children aged 6 to 23 months. IYCF practices were assessed using 24-hour dietary recall. Logistic regression was used to identify predictors of IYCF practices. All analyses accounted for sampling stratification by child's age group and for data clustering. RESULTS: According to mothers' reports, 60% (95%CI 55, 65%) of children received the minimum meal frequency, but only 18% (95%CI 15, 22%) and 13% (95%CI 10, 16%) benefited from the minimum dietary diversity and the minimum acceptable diet respectively. Only 16% (95%CI 13, 20%) of mothers reported increasing breastfeeding or liquids and continued feeding during an episode of child illness. Knowledge of timely introduction of complementary foods and recommended feeding practices during an illness were low. Despite positive attitudes towards the introduction of key food groups, mother's perceived self-efficacy to provide children with these food groups every day was relatively low. DISCUSSION: Our findings highlight the need for interventions to improve mothers' knowledge and practices in relation to IYCF in the Boucle du Mouhoun region. Behaviour change communication strategies have the potential to improve IYCF indicators but should be tailored to the local context. The high attendance of health facilities for preventive well-baby consultations represents an opportunity for contact with caretakers that should be exploited for promotion and child growth monitoring

    Warped Reheating in Multi-Throat Brane Inflation

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    We investigate in some quantitative details the viability of reheating in multi-throat brane inflationary scenarios by estimating and comparing the time scales for the various processes involved. We also calculate within perturbative string theory the decay rate of excited closed strings into KK modes and compare with that of their decay into gravitons; we find that in the inflationary throat the former is preferred. We also find that over a small but reasonable range of parameters of the background geometry, these KK modes will preferably tunnel to another throat (possibly containing the Standard Model) instead of decaying to gravitons due largely to their suppressed coupling to the bulk gravitons. Once tunneled, the same suppressed coupling to the gravitons again allows them to reheat the Standard Model efficiently. We also consider the effects of adding more throats to the system and find that for extra throats with small warping, reheating still seems viable.Comment: 29 pages, 4 figures, discussions on closed string decay expanded, references adde

    DBI Inflation in the Tip Region of a Warped Throat

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    Previous work on DBI inflation, which achieves inflation through the motion of a D3D3 brane as it moves through a warped throat compactification, has focused on the region far from the tip of the throat. Since reheating and other observable effects typically occur near the tip, a more detailed study of this region is required. To investigate these effects we consider a generalized warp throat where the warp factor becomes nearly constant near the tip. We find that it is possible to obtain 60 or more e-folds in the constant region, however large non-gaussianities are typically produced due to the small sound speed of fluctuations. For a particular well-studied throat, the Klebanov-Strassler solution, we find that inflation near the tip may be generic and it is difficult to satisfy current bounds on non-gaussianity, but other throat solutions may evade these difficulties.Comment: 26 pages, 1 figure. v1. references added, typos corrected v2. clarifications mad
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