17,235 research outputs found
Why is child malnutrition lower in urban than rural areas?
"While ample evidence documents that urban children generally have better nutritional status than their rural counterparts, recent research suggests that urban malnutrition is on the rise. The environment, choices, and opportunities of urbanites differ greatly from those of rural dwellers' from employment conditions to social and family networks to access to health care and other services. Given these differences, understanding the relative importance of the various determinants of child malnutrition in urban and rural areas and especially whether they differ is key to designing context-relevant, effective program and policy responses for stemming malnutrition. This study uses Demographic and Health Survey data from 36 developing countries to address the question of whether the socioeconomic determinants of child nutritional status differ across urban and rural areas. The purpose is to answer the broader question of why child malnutrition rates are lower in urban areas. The socioeconomic determinants examined are women's education, women's status, access to safe water and sanitation, and household economic status. The analysis finds little evidence of differences in the nature of the socioeconomic determinants or in the strength of their associations with child nutritional status across urban and rural areas. As expected, however, it documents marked differences in the levels of these determinants in favor of urban areas. Large gaps in favor of urban areas are also found in the levels of key proximate determinants of child nutritional status, especially maternal prenatal and birthing care, quality of complementary feeding, and immunization of children. The conclusion is that better nutritional status of urban children is probably due to the cumulative effect of a series of more favorable socioeconomic conditions, which, in turn, seems to lead to better caring practices for children and their mothers. Given that the nature of the determinants of child nutritional status is largely the same across urban and rural areas, the same program and policy framework can be used to stem malnutrition in both. Efforts to alleviate the most critical socioeconomic constraints specific to the different environments should continue to be prioritized." Authors' Abstractmalnutrition ,Demographic and Health Survey ,
Why is child malnutrition lower in urban than rural areas?
"While ample evidence documents that urban children generally have better nutritional status than their rural counterparts, recent research suggests that urban malnutrition is on the rise. The environment, choices, and opportunities of urbanites differ greatly from those of rural dwellers' from employment conditions to social and family networks to access to health care and other services. Given these differences, understanding the relative importance of the various determinants of child malnutrition in urban and rural areas and especially whether they differ is key to designing context-relevant, effective program and policy responses for stemming malnutrition. This study uses Demographic and Health Survey data from 36 developing countries to address the question of whether the socioeconomic determinants of child nutritional status differ across urban and rural areas. The purpose is to answer the broader question of why child malnutrition rates are lower in urban areas. The socioeconomic determinants examined are women's education, women's status, access to safe water and sanitation, and household economic status. The analysis finds little evidence of differences in the nature of the socioeconomic determinants or in the strength of their associations with child nutritional status across urban and rural areas. As expected, however, it documents marked differences in the levels of these determinants in favor of urban areas. Large gaps in favor of urban areas are also found in the levels of key proximate determinants of child nutritional status, especially maternal prenatal and birthing care, quality of complementary feeding, and immunization of children. The conclusion is that better nutritional status of urban children is probably due to the cumulative effect of a series of more favorable socioeconomic conditions, which, in turn, seems to lead to better caring practices for children and their mothers. Given that the nature of the determinants of child nutritional status is largely the same across urban and rural areas, the same program and policy framework can be used to stem malnutrition in both. Efforts to alleviate the most critical socioeconomic constraints specific to the different environments should continue to be prioritized." Authors' Abstractmalnutrition ,Demographic and Health Survey ,
Splitting between Bright and Dark excitons in Transition Metal Dichalcogenide Monolayers
The optical properties of transition metal dichalcogenide monolayers such as
the two-dimensional semiconductors MoS and WSe are dominated by
excitons, Coulomb bound electron-hole pairs. The light emission yield depends
on whether the electron-hole transitions are optically allowed (bright) or
forbidden (dark). By solving the Bethe Salpeter Equation on top of wave
functions in density functional theory calculations, we determine the sign and
amplitude of the splitting between bright and dark exciton states. We evaluate
the influence of the spin-orbit coupling on the optical spectra and clearly
demonstrate the strong impact of the intra-valley Coulomb exchange term on the
dark-bright exciton fine structure splitting.Comment: 6 pages, 2 figure
Tidal Disruption of Protoclusters in Giant Molecular Clouds
We study the collapse of protoclusters within a giant molecular cloud (GMC)
to determine the conditions under which collapse is significantly disrupted.
Motivated by observations of star forming regions which exhibit flattened cloud
structures, this study considers collapsing protoclusters with disk geometries.
The collapse of a 10^3 Msun protocluster initially a distance of 2-10 pc from a
10^3 - 10^6 Msun point mass is numerically calculated. Simulations with zero
initial relative velocity between the two are completed as well as simulations
with relative velocities consistent with those observed in GMCs. The results
allow us to define the conditions under which it is safe to assume protocluster
collapse proceeds as if in isolation. For instance, we find the collapse of a
10^3 Msun protocluster will be significantly disrupted if it is within 2-4 pc
of a 10^4 Msun point mass. Thus, the collapse of a 10^3 Msun protocluster can
be considered to proceed as if in isolation if it is more than ~ 4 pc away from
a 10^4 Msun compact object. In addition, in no portion of the sampled parameter
space does the gravitational interaction between the protocluster disk and the
massive particle significantly disperse the disk into the background GMC. We
discuss the distribution of clusters of young stellar objects within the
Perseus and Mon R2 star forming regions, which are consistent with the results
of our simulations and the limitations of our results in gas dominated regions
such as the Orion cloud.Comment: 12 pages, 6 figures, Accepted for publication in Ap
Impact of heavy hole-light hole coupling on optical selection rules in GaAs quantum dots
We report strong heavy hole-light mixing in GaAs quantum dots grown by
droplet epitaxy. Using the neutral and charged exciton emission as a monitor we
observe the direct consequence of quantum dot symmetry reduction in this strain
free system. By fitting the polar diagram of the emission with simple
analytical expressions obtained from kp theory we are able to extract
the mixing that arises from the heavy-light hole coupling due to the
geometrical asymmetry of the quantum dot.Comment: 4 pages, 2 figure
Giant spin-dependent photo-conductivity in GaAsN dilute nitride semiconductor
A theoretical and experimental study of the spin-dependent photoconductivity
in dilute Nitride GaAsN is presented. The non linear transport model we develop
here is based on the rate equations for electrons, holes, deep paramagnetic and
non paramagnetic centers both under CW and pulsed optical excitation. Emphasis
is given to the effect of the competition between paramagnetic centers and non
paramagnetic centers which allows us to reproduce the measured characteristics
of the spin-dependent recombination power dependence. Particular attention is
paid to the role of an external magnetic field in Voigt geometry. The
photoconductivity exhibits a Hanle-type curve whereas the spin polarization of
electrons shows two superimposed Lorentzian curves with different widths,
respectively related to the recombination of free and trapped electrons. The
model is capable of reproducing qualitatively and quantitatively the most
important features of photoluminescence and photocurrent experiments and is
helpful in providing insight on the various mechanisms involved in the electron
spin polarization and filtering in GaAsN semiconductors.Comment: 10 pages, 5 figure
Development and evaluation of lessons for class and group situations in grade one
Thesis (Ed.M.)--Boston Universit
Bunching visibility for correlated photons from single GaAs quantum dots
We study photon bunching phenomena associated with biexciton-exciton cascade
in single GaAs self-assembled quantum dots. Experiments carried out with a
pulsed excitation source show that significant bunching is only detectable at
very low excitation, where the typical intensity of photon streams is less than
the half of their saturation value. Our findings are qualitatively understood
with a model which accounts for Poissonian statistics in the number of
excitons, predicting the height of a bunching peak being determined by the
inverse of probability of finding more than one exciton.Comment: 6 pages, 6 figs to appear in Phys. Rev.
Maladie mentale et stigmatisation ou Comment on devient un malade mental pour la vie
La perspective sociologique telle que prĂ©sentĂ©e ici en relation avec la santĂ© et/ou la maladie mentale est basĂ©e sur une approche interactionniste du phĂ©nomĂšne. En effet, la sociĂ©tĂ© est composĂ©e d'un ensemble de normes et de valeurs, partagĂ©es par la majoritĂ© des personnes au sein d'une mĂȘme culture Ă une Ă©poque donnĂ©e. Ces normes dont l'apprentissage commence dĂšs la naissance de l'individu, sont issues de la gĂ©nĂ©ration prĂ©cĂ©dente et ainsi transmises de gĂ©nĂ©ration en gĂ©nĂ©ration. Normes et valeurs constituent le tissu social, fondement de notre vie en commun. Il s'agit d'une vision de la sociĂ©tĂ© centrĂ©e principalement sur les rapports entre les individus et la sociĂ©tĂ©, et entre les individus et les institutions, ces rapports Ă©tant dĂ©finis par un ensemble d'interdĂ©pendance psychologique et sociale.In this article mental illness is presented in a sociological perspective, giving prominence to social-interaction factors which, in many cases, are responsable for the permanence of this type of illness. Its thereotical base comes !form the psychology of social-interaction developped by G.H. Mead and his disciples. This perspective defines the social human being as derived from successive interactions, beginning, at birth, with maternal contacts and extending progressively to the entirety of the members of the community of which the individual is a part. This interactional network is comprised of messages, of responses, and of expectations which make up the norms and values which in turn from the basis for the distribution of roles and statuses- From these roles and statuses derive the behaviours acceptable to a given collectivity. Among other theoretical developments, interactionist sociology gave birth to formulations on deviance which became known, in american terminology as "labelling theory". In the case of mental illness many sociologists interested in the phenomenon have studied it, using the framework elaborated by the proponents of this approach to deviance. Thus, rather than considering the deviant as abnormal in himself, deviance is viewed as a process; that is, as the result of a series of interactions confronting the individual who is not, or does not behave like the collectivity as a whole and the milieu in which he lives. When the reaction of the entourage is negative, the so-called deviant is subjected to sanctions such as avoidance, rejection, exclusion, confinement, etc... This process terminates generally in stigmatization which wraps the deviant in a label from which he will probably never free himself. The studies cited demonstrate this interactional process at different stages of mental illness, these being; d) at the point of medical diagnosis, b) during hospitalisation, c) on leaving We psychiatric institution, d) and after the return to society. The conclusion leads to an appreciation of the drama experienced by psychiatric ex-patients, for most of whom the label "mentally ill" constitutes an apparently irreversible stigmatization
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