5,319 research outputs found
Electronic scanning pressure measuring system and transducer package
An electronic scanning pressure system that includes a plurality of pressure transducers is examined. A means obtains an electrical signal indicative of a pressure measurement from each of the plurality of pressure transducers. A multiplexing means is connected for selectivity supplying inputs from the plurality of pressure transducers to the signal obtaining means. A data bus connects the plurality of pressure transducers to the multiplexing means. A latch circuit is connected to supply control inputs to the multiplexing means. An address bus is connected to supply an address signal of a selected one of the plurality of pressure transducers to the latch circuit. In operation, each of the pressure transducers is successively scanned by the multiplexing means in response to address signals supplied on the address bus to the latch circuit
Symmetry breaking in MAST plasma turbulence due to toroidal flow shear
The flow shear associated with the differential toroidal rotation of tokamak
plasmas breaks an underlying symmetry of the turbulent fluctuations imposed by
the up-down symmetry of the magnetic equilibrium. Using experimental
Beam-Emission-Spectroscopy (BES) measurements and gyrokinetic simulations, this
symmetry breaking in ion-scale turbulence in MAST is shown to manifest itself
as a tilt of the spatial correlation function and a finite skew in the
distribution of the fluctuating density field. The tilt is a statistical
expression of the "shearing" of the turbulent structures by the mean flow. The
skewness of the distribution is related to the emergence of long-lived density
structures in sheared, near-marginal plasma turbulence. The extent to which
these effects are pronounced is argued (with the aid of the simulations) to
depend on the distance from the nonlinear stability threshold. Away from the
threshold, the symmetry is effectively restored
Turbulent transport in tokamak plasmas with rotational shear
Nonlinear gyrokinetic simulations have been conducted to investigate
turbulent transport in tokamak plasmas with rotational shear. At sufficiently
large flow shears, linear instabilities are suppressed, but transiently growing
modes drive subcritical turbulence whose amplitude increases with flow shear.
This leads to a local minimum in the heat flux, indicating an optimal E x B
shear value for plasma confinement. Local maxima in the momentum fluxes are
also observed, allowing for the possibility of bifurcations in the E x B shear.
The sensitive dependence of heat flux on temperature gradient is relaxed for
large flow shear values, with the critical temperature gradient increasing at
lower flow shear values. The turbulent Prandtl number is found to be largely
independent of temperature and flow gradients, with a value close to unity.Comment: 4 pages, 5 figures, submitted to PR
Multilevel correlates of household anthropometric typologies in Colombian mothers and their infants
Background. The aim of this study was to establish the association of maternal, family, and contextual correlates of anthropometric typologies at the household level in Colombia using 2005 Demographic Health Survey (DHS/ENDS) data.Methods. Household-level information from mothers 18-49 years old and their children less than 5 years old was included. Stunting and overweight were assessed for each child. Mothers were classified according to their body mass index. Four anthropometric typologies at the household level were constructed: normal, underweight, overweight, and dual burden. Four three-level [households (n = 8598) nested within municipalities (n = 226), nested within states (n = 32)] hierarchical polytomous logistic models were developed. Household log-odds of belonging to one of the four anthropometric categories, holding 'normal' as the reference group, were obtained.Results. This study found that anthropometric typologies were associated with maternal and family characteristics of maternal age, parity, maternal education, and wealth index. Higher municipal living conditions index was associated with a lower likelihood of underweight typology and a higher likelihood of overweight typology. Higher population density was associated with a lower likelihood of overweight typology.Conclusion. Distal and proximal determinants of the various anthropometric typologies at the household level should be taken into account when framing policies and designing interventions to reduce malnutrition in Colombia. Copyright © The Author(s) 2018
Maternal and familial correlates of anthropometric typologies in the nutrition transition of Colombia, 2000–2010
Q2Q1Objective: We aimed to assess the maternal and family determinants of four
anthropometric typologies at the household level in Colombia for the years 2000,
2005 and 2010.
Design: We classified children <5 years old according to height-for-age Z-score
(2) to assess stunting and overweight/obesity,
respectively; mothers were categorized according to BMI to assess underweight
(<18·5 kg/m2
) and overweight/obesity (≥25·0 kg/m2
). At the household level, we
established four final anthropometric typologies: normal, underweight, overweight and dual-burden households. Separate polytomous logistic regression
models for each of the surveyed years were developed to examine several
maternal and familial determinants of the different anthropometric typologies.
Setting: National and sub-regional (urban and rural) representative samples from
Colombia, South America.
Subjects: Drawing on data from three waves of Colombia’s Demographic and
Health Survey/Encuesta Nacional de Salud (DHS/ENDS), we examined individual
and household information from mothers (18–49 years) and their children (birth–
5 years).
Results: Higher parity was associated with an increased likelihood of overweight
and dual burden. Higher levels of maternal education were correlated with lower
prevalence of overweight, underweight and dual burden of malnutrition in all data
collection waves. In 2010, participation in nutrition programmes for children
<5 years, being an indigenous household, food purchase decisions by the mother
and food security classification were also associated with the four anthropometric
typologies.
Conclusions: Results suggest that maternal and family correlates of certain
anthropometric typologies at the household level may be used to better frame
policies aimed at improving social conditions and nutrition outcomes.Revista Internacional - Indexad
Maternal and familial correlates of anthropometric typologies in the nutrition transition of Colombia, 2000–2010
Zero-Turbulence Manifold in a Toroidal Plasma
Sheared toroidal flows can cause bifurcations to zero-turbulent-transport
states in tokamak plasmas. The maximum temperature gradients that can be
reached are limited by subcritical turbulence driven by the parallel velocity
gradient. Here it is shown that q/\epsilon (magnetic field pitch/inverse aspect
ratio) is a critical control parameter for sheared tokamak turbulence. By
reducing q/\epsilon, far higher temperature gradients can be achieved without
triggering turbulence, in some instances comparable to those found
experimentally in transport barriers. The zero-turbulence manifold is mapped
out, in the zero-magnetic-shear limit, over the parameter space (\gamma_E,
q/\epsilon, R/L_T), where \gamma_E is the perpendicular flow shear and R/L_T is
the normalised inverse temperature gradient scale. The extent to which it can
be constructed from linear theory is discussed.Comment: 5 Pages, 4 Figures, Submitted to PR
Transport Bifurcation in a Rotating Tokamak Plasma
The effect of flow shear on turbulent transport in tokamaks is studied
numerically in the experimentally relevant limit of zero magnetic shear. It is
found that the plasma is linearly stable for all non-zero flow shear values,
but that subcritical turbulence can be sustained nonlinearly at a wide range of
temperature gradients. Flow shear increases the nonlinear temperature gradient
threshold for turbulence but also increases the sensitivity of the heat flux to
changes in the temperature gradient, except over a small range near the
threshold where the sensitivity is decreased. A bifurcation in the equilibrium
gradients is found: for a given input of heat, it is possible, by varying the
applied torque, to trigger a transition to significantly higher temperature and
flow gradients.Comment: 4 pages, 4 figures, submitted to PR
Ion-scale turbulence in MAST: anomalous transport, subcritical transitions, and comparison to BES measurements
We investigate the effect of varying the ion temperature gradient (ITG) and
toroidal equilibrium scale sheared flow on ion-scale turbulence in the outer
core of MAST by means of local gyrokinetic simulations. We show that nonlinear
simulations reproduce the experimental ion heat flux and that the
experimentally measured values of the ITG and the flow shear lie close to the
turbulence threshold. We demonstrate that the system is subcritical in the
presence of flow shear, i.e., the system is formally stable to small
perturbations, but transitions to a turbulent state given a large enough
initial perturbation. We propose that the transition to subcritical turbulence
occurs via an intermediate state dominated by low number of coherent long-lived
structures, close to threshold, which increase in number as the system is taken
away from the threshold into the more strongly turbulent regime, until they
fill the domain and a more conventional turbulence emerges. We show that the
properties of turbulence are effectively functions of the distance to
threshold, as quantified by the ion heat flux. We make quantitative comparisons
of correlation lengths, times, and amplitudes between our simulations and
experimental measurements using the MAST BES diagnostic. We find reasonable
agreement of the correlation properties, most notably of the correlation time,
for which significant discrepancies were found in previous numerical studies of
MAST turbulence.Comment: 67 pages, 37 figures. Submitted to PPC
The ROCK inhibitor Fasudil prevents chronic restraint stress-induced depressive-like behaviors and dendritic spine loss in rat hippocampus
Indexación: Web of Science; Scopus.Background: Dendritic arbor simplification and dendritic spine loss in the hippocampus, a limbic structure implicated in mood disorders, are assumed to contribute to symptoms of depression. These morphological changes imply modifications in dendritic cytoskeleton. Rho GTPases are regulators of actin dynamics through their effector Rho kinase. We have reported that chronic stress promotes depressive-like behaviors in rats along with dendritic spine loss in apical dendrites of hippocampal pyramidal neurons, changes associated with Rho kinase activation. The present study proposes that the Rho kinase inhibitor Fasudil may prevent the stress-induced behavior and dendritic spine loss. Methods: Adult male Sprague-Dawley rats were injected with saline or Fasudil (i.p., 10 mg/kg) starting 4 days prior to and maintained during the restraint stress procedure (2.5 h/d for 14 days). Nonstressed control animals were injected with saline or Fasudil for 18 days. At 24 hours after treatment, forced swimming test, Golgi-staining, and immuno-western blot were performed. Results: Fasudil prevented stress-induced immobility observed in the forced swimming test. On the other hand, Fasudiltreated control animals showed behavioral patterns similar to those of saline-treated controls. Furthermore, we observed that stress induced an increase in the phosphorylation of MYPT1 in the hippocampus, an exclusive target of Rho kinase. This change was accompanied by dendritic spine loss of apical dendrites of pyramidal hippocampal neurons. Interestingly, increased pMYPT1 levels and spine loss were both prevented by Fasudil administration. Conclusion: Our findings suggest that Fasudil may prevent the development of abnormal behavior and spine loss induced by chronic stress by blocking Rho kinase activity.https://academic.oup.com/ijnp/article/20/4/336/263217
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