18,513 research outputs found
Evaluation of Data and Tools from CGIAR Research Program on Climate Change, Agriculture, and Food Security (CCAFS)
This report assesses nine CCAFS tools/datasets in terms of who is using them and for what purposes, and explores whether and how the use of CCAFS data and tools has contributed to outcomes, in particular to changes in knowledge, attitude or skills, as well as potential changes in behaviour and practice among different user groups, where possible
The Diet, Physical Activity and Accommodation of Patients with Quiescent Pulmonary Tuberculosis in a Poor South Indian Community
A previous report from the Tuberculosis Chemotherapy Centre, Madras, has shown
that, if standard chemotherapy is given for one year, the response of patients treated at
home in very poor environmental circumstances is nearly as good as that of those treated
in sanatorium under much more favourable conditions. This paper reports on a four-year
follow-up of all the patients whose disease was bacteriologically quiescent at the end of the
year’s treatment. During this period, all the patients were managed on a domiciliary basis :
about a quarter of them received chemotherapy with isoniazid alone for two years, another
quarter received the drug for one year and the rest received no specific chemotherapy. Despite
adverse environmental factors (poor diet ; long hours of work often involving strenuous
physical activity ; overcrowded living conditions ; and, for the sanatorium patients, the
stresses of returning suddenly to the unfavourable home environment), the great majority
of patients in both series maintained quiescent disease throughout the follow-up period.
Furthermore, the few patients whose disease relapsed bacteriologically were at no special
dietary disadvantage in comparison with those who maintained quiescent disease throughout,
nor did they show any appreciable differences in occupation, physical activity or living
accommodation. These findings, together with the earlier ones, indicate that, despite
adverse environmental circumstances, standard chemotherapy for an adequate period
of time is sufficient in the great majority of patients for the attainment of bacteriological
quiescence and its maintenance thereafter
Sediment Transport Model for Seepage Erosion of Streambank Sediment
Erosion by lateral, subsurface flow is known to erode streambank sediment in numerous geographical locations; however, the role of seepage erosion on mass failure of streambanks is not well understood. In the absence of an established sediment transport model for seepage erosion, the objectives of this research were to investigate the mechanisms of erosion due to concentrated, lateral subsurface flow and develop an empirical sediment transport model for seepage erosion of noncohesive sediment on near-vertical streambanks. Laboratory experiments were performed using a two-dimensional soil lysimeter of a reconstructed streambank profile packed with three different soil layers to mimic seepage erosion occurring at Little Topashaw Creek (LTC) in northern Mississippi. Soil samples from LTC streambanks indicated considerable hydraulic conductivity contrast between an overlying silt loam layer (SiL), highly permeable loamy sand, and confining clay loam layer. Lysimeter experiments were conducted with various upstream water table heads, overburden heights, and lysimeter slopes. Bank failure occurred prior to the total release of negative pore-water pressures in the SiL layer suggesting that such a mechanism was not critical for bank collapse due to seepage erosion. A seepage erosion transport model for conductive, noncohesive soil layers was derived based on a dimensionless sediment discharge and dimensionless seepage flow shear stress. The advantage of this sediment transport model is that it relates sediment flux to seepage discharge from the streambank
Resolution of high and low affinity progesterone receptors from human breast carcinoma T47D cells
Each of four independent experimental approaches showed that human breast carcinoma T47D cells contain both high and low affinity progesterone receptors. (i) Equilibrium-specific [3H]progesterone binding to adherent cultured cells revealed dissociation constants (Kd) of 1.5 and 60 nM and 0.33 and 2.4×106 sites/cell, respectively. Both the high and low affinity receptors were specific for progestins as demonstrated by steroid binding competition studies conducted at 5 and 50 nM [3H]progesterone. (ii) Equilibrium [3H]progesterone binding to the resolved soluble and particulate fractions from a cell homogenate sedimented at 40,000×g.min revealed Kd=1.4 nM high affinity binding sites exclusively in the supernatant fraction and Kd=24 nM low affinity sites exclusively in the particulate fraction. Extraction of the particulate fraction with a high ionic strength buffer solubilized the low affinity receptors stoichiometrically; but once solubilized, they displayed Kd=2.4 nM high affinity progesterone binding. Characterizations of 3H-ligand bound specifically to progesterone receptors in intact cells or resolved subcellular fractions revealed no [3H]progesterone metabolites that could account for the low affinity binding. (iii) Calculations based on the rate constants of [3H] progesterone association with or dissociation from adherent cells revealed the same dissociation constants for both high and low affinity binding as those determined by equilibrium measurements. (iv) Nonionic detergent extraction of cells incubated with a wide range of [3H]progesterone concentrations revealed high affinity progesterone binding to receptors in the detergent-soluble fraction and low affinity binding associated primarily with the particulate residue, consistent with the data on equilibrium progesterone binding to resolved cell homogenate fractions. The rate of extraction of the high affinity receptor-progesterone complex with nonionic detergent (t½=1 min at 0°C) equaled the rate of extraction of a representative lysosomal enzyme, β-acetylglucosaminidase
Sediment Transport Model for Seepage Erosion of Streambank Sediment
Erosion by lateral, subsurface flow is known to erode streambank sediment in numerous geographical locations; however, the role of seepage erosion on mass failure of streambanks is not well understood. In the absence of an established sediment transport model for seepage erosion, the objectives of this research were to investigate the mechanisms of erosion due to concentrated, lateral subsurface flow and develop an empirical sediment transport model for seepage erosion of noncohesive sediment on near-vertical streambanks. Laboratory experiments were performed using a two-dimensional soil lysimeter of a reconstructed streambank profile packed with three different soil layers to mimic seepage erosion occurring at Little Topashaw Creek (LTC) in northern Mississippi. Soil samples from LTC streambanks indicated considerable hydraulic conductivity contrast between an overlying silt loam layer (SiL), highly permeable loamy sand, and confining clay loam layer. Lysimeter experiments were conducted with various upstream water table heads, overburden heights, and lysimeter slopes. Bank failure occurred prior to the total release of negative pore-water pressures in the SiL layer suggesting that such a mechanism was not critical for bank collapse due to seepage erosion. A seepage erosion transport model for conductive, noncohesive soil layers was derived based on a dimensionless sediment discharge and dimensionless seepage flow shear stress. The advantage of this sediment transport model is that it relates sediment flux to seepage discharge from the streambank
Renormalization Group Study of the soliton mass on the (lambda Phi^4)_{1+1} lattice model
We compute, on the model on the lattice, the soliton
mass by means of two very different numerical methods. First, we make use of a
``creation operator'' formalism, measuring the decay of a certain correlation
function. On the other hand we measure the shift of the vacuum energy between
the symmetric and the antiperiodic systems. The obtained results are fully
compatible.
We compute the continuum limit of the mass from the perturbative
Renormalization Group equations. Special attention is paid to ensure that we
are working on the scaling region, where physical quantities remain unchanged
along any Renormalization Group Trajectory. We compare the continuum value of
the soliton mass with its perturbative value up to one loop calculation. Both
quantities show a quite satisfactory agreement. The first is slightly bigger
than the perturbative one; this may be due to the contributions of higher order
corrections.Comment: 19 pages, preprint DFTUZ/93/0
Blobs in Wolf-Rayet Winds: Random Photometric and Polarimetric Variability
Some isolated Wolf-Rayet stars present random variability in their optical
flux and polarization. We make the assumption that such variability is caused
by the presence of regions of enhanced density, i.e. blobs, in their envelopes.
In order to find the physical characteristics of such regions we have modeled
the stellar emission using a Monte Carlo code to treat the radiative transfer
in an inhomogeneous electron scattering envelope. We are able to treat multiple
scattering in the regions of enhanced density as well as in the envelope
itself. The finite sizes of the source and structures in the wind are also
taken into account. Most of the results presented here are based on a parameter
study of models with a single blob. The effects due to multiple blobs in the
envelope are considered to a more limited extent. Our simulations indicate that
the density enhancements must have a large geometric cross section in order to
produce the observed photopolarimetric variability. The sizes must be of the
order of one stellar radius and the blobs must be located near the base of the
envelope. These sizes are the same inferred from the widths of the sub-peaks in
optical emission lines of Wolf-Rayet stars. Other early-type stars show random
polarimetric fluctuations with characteristics similar to those observed in
Wolf-Rayet stars, which may also be interpreted in terms of a clumpy wind.
Although the origin of such structures is still unclear, the same mechanism may
be working in different types of hot stars envelopes to produce such
inhomogeneities.Comment: Accepted to ApJ. 17 pages + 6 figure
Has the phasing out of stavudine in accordance with changes in WHO guidelines led to a decrease in single-drug substitutions in first-line antiretroviral therapy for HIV in sub-Saharan Africa?
This version is the Accepted Manuscript and is published in final edited form as:
AIDS. 2017 January 02; 31(1): 147–157. doi:10.1097/QAD.0000000000001307OBJECTIVE: We assessed the relationship between phasing out stavudine in first-line antiretroviral therapy (ART) in accordance with WHO 2010 policy and single-drug substitutions (SDS) (substituting the nucleoside reverse transcriptase inhibitor in first-line ART) in sub-Saharan Africa.
DESIGN: Prospective cohort analysis (International epidemiological Databases to Evaluate AIDS-Multiregional) including ART-naive, HIV-infected patients aged at least 16 years, initiating ART between January 2005 and December 2012. Before April 2010 (July 2007 in Zambia) national guidelines called for patients to initiate stavudine-based or zidovudine-based regimen, whereas thereafter tenofovir or zidovudine replaced stavudine in first-line ART.
METHODS: We evaluated the frequency of stavudine use and SDS by calendar year 2004-2014. Competing risk regression was used to assess the association between nucleoside reverse transcriptase inhibitor use and SDS in the first 24 months on ART.
RESULTS: In all, 33 441 (8.9%; 95% confience interval 8.7-8.9%) SDS occurred among 377 656 patients in the first 24 months on ART, close to 40% of which were amongst patients on stavudine. The decrease in SDS corresponded with the phasing out of stavudine. Competing risks regression models showed that patients on tenofovir were 20-95% less likely to require a SDS than patients on stavudine, whereas patients on zidovudine had a 75-85% decrease in the hazards of SDS when compared to stavudine.
CONCLUSION: The decline in SDS in the first 24 months on treatment appears to be associated with phasing out stavudine for zidovudine or tenofovir in first-line ART in our study. Further efforts to decrease the cost of tenofovir and zidovudine for use in this setting is warranted to substitute all patients still receiving stavudine
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