519 research outputs found
Dielectric and conductivity relaxation in mixtures of glycerol with LiCl
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
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
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
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 , 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
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
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.
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
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
Previous work on DBI inflation, which achieves inflation through the motion
of a 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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