822 research outputs found
Emerging stronger? Assessing the outcomes of Habitat for Humanity’s housing reconstruction programmes following the Indian Ocean tsunami
Habitat for Humanity (HFH) built, rehabilitated or repaired homes for 25,000 families
in four countries in the five years following the Indian Ocean tsunami in 2004. As part
of a broader organizational and learning review in 2009-2010, HFH commissioned
Arup International Development to carry out an assessment of its post-tsunami housing
reconstruction programmes in India, Sri Lanka, Thailand, and Indonesia. The purpose
of this assessment was to investigate the extent to which HFH’s tsunami-response
housing reconstruction programmes had contributed to the development of sustainable
communities and livelihoods. Arup International Development undertook the assessment
using the ASPIRE tool they had developed with Engineers Against Poverty. Basing their
assessment on programme documentation and key informant interviews, household
questionnaires and workshops with communities in each country, they completed one
assessment for each country and a fifth assessment covering all four countries. This
enabled comparison of both the impact of these four programmes and how the outcomes
varied as a result of varying approaches and contextual issues. / The assessment found that HFH’s programme had made a significant contribution to
the development of sustainable communities and livelihoods. The provision of high
quality core homes had reduced household vulnerability and increased the standard
of living, while HFH’s participatory process had increased community cohesion and
developed positive relationships between communities and a range of external actors.
There were also areas for improvement such as: the incorporation of hazard assessment,
settlement planning and infrastructure at settlement level; greater community
participation in decision-making regarding settlement planning, house design and
the choice of appropriate construction techniques and technologies; greater focus on
livelihood support and diversification both during construction and after completion of
the housing programme; and complementing HFH’s experience in housing construction
with the specialist expertise of other actors to maximize the impact of its work
The need to promote behaviour change at the cultural level: one factor explaining the limited impact of the MEMA kwa Vijana adolescent sexual health intervention in rural Tanzania. A process evaluation
Background - Few of the many behavioral sexual health interventions in Africa have been rigorously evaluated. Where biological outcomes have been measured, improvements have rarely been found. One of the most rigorous trials was of the multi-component MEMA kwa Vijana adolescent sexual health programme, which showed improvements in knowledge and reported attitudes and behaviour, but none in biological outcomes. This paper attempts to explain these outcomes by reviewing the process evaluation findings, particularly in terms of contextual factors.
Methods - A large-scale, primarily qualitative process evaluation based mainly on participant observation identified the principal contextual barriers and facilitators of behavioural change.
Results - The contextual barriers involved four interrelated socio-structural factors: culture (i.e. shared practices and systems of belief), economic circumstances, social status, and gender. At an individual level they appeared to operate through the constructs of the theories underlying MEMA kwa Vijana - Social Cognitive Theory and the Theory of Reasoned Action – but the intervention was unable to substantially modify these individual-level constructs, apart from knowledge.
Conclusion - The process evaluation suggests that one important reason for this failure is that the intervention did not operate sufficiently at a structural level, particularly in regard to culture. Recently most structural interventions have focused on gender or/and economics. Complementing these with a cultural approach could address the belief systems that justify and perpetuate gender and economic inequalities, as well as other barriers to behaviour change
Bi-local Construction of Sp(2N)/dS Higher Spin Correspondence
We derive a collective field theory of the singlet sector of the Sp(2N) sigma
model. Interestingly the hamiltonian for the bilocal collective field is the
same as that of the O(N) model. However, the large-N saddle points of the two
models differ by a sign. This leads to a fluctuation hamiltonian with a
negative quadratic term and alternating signs in the nonlinear terms which
correctly reproduces the correlation functions of the singlet sector. Assuming
the validity of the connection between O(N) collective fields and higher spin
fields in AdS, we argue that a natural interpretation of this theory is by a
double analytic continuation, leading to the dS/CFT correspondence proposed by
Anninos, Hartman and Strominger. The bi-local construction gives a map into the
bulk of de Sitter space-time. Its geometric pseudospin-representation provides
a framework for quantization and definition of the Hilbert space. We argue that
this is consistent with finite N grassmanian constraints, establishing the
bi-local representation as a nonperturbative framework for quantization of
Higher Spin Gravity in de Sitter space.Comment: 1 figur
Gravitational collapse of a Hagedorn fluid in Vaidya geometry
The gravitational collapse of a high-density null charged matter fluid,
satisfying the Hagedorn equation of state, is considered in the framework of
the Vaidya geometry. The general solution of the gravitational field equations
can be obtained in an exact parametric form. The conditions for the formation
of a naked singularity, as a result of the collapse of the compact object, are
also investigated. For an appropriate choice of the arbitrary integration
functions the null radial outgoing geodesic, originating from the shell
focussing central singularity, admits one or more positive roots. Hence a
collapsing Hagedorn fluid could end either as a black hole, or as a naked
singularity. A possible astrophysical application of the model, to describe the
energy source of gamma-ray bursts, is also considered.Comment: 14 pages, 2 figures, to appear in Phys. Rev.
Magnetic resonance imaging in the diagnosis of white matter signal abnormalities.
Background White matter abnormalities (WMAs) pose a diagnostic challenge when trying to establish etiologic diagnoses. During childhood and adult years, genetic disorders, metabolic disorders and acquired conditions are included in differential diagnoses. To assist clinicians and radiologists, a structured algorithm using cranial magnetic resonance imaging (MRI) has been recommended to aid in establishing working diagnoses that facilitate appropriate biochemical and genetic investigations. This retrospective pilot study investigated the validity and diagnostic utility of this algorithm when applied to white matter signal abnormalities (WMSAs) reported on imaging studies of patients seen in our clinics. Methods The MRI algorithm was applied to 31 patients selected from patients attending the neurometabolic/neurogenetic/metabolic/neurology clinics at a tertiary care hospital. These patients varied in age from 5 months to 79 years old, and were reported to have WMSAs on cranial MRI scans. Twenty-one patients had confirmed WMA diagnoses and 10 patients had non-specific WMA diagnoses (etiology unknown). Two radiologists, blinded to confirmed diagnoses, used clinical abstracts and the WMSAs present on patient MRI scans to classify possible WMA diagnoses utilizing the algorithm. Results The MRI algorithm displayed a sensitivity of 100%, a specificity of 30.0% and a positive predicted value of 74.1%. Cohen\u27s kappa statistic for inter-radiologist agreement was 0.733, suggesting good agreement between radiologists. Conclusions Although a high diagnostic utility was not observed, results suggest that this MRI algorithm has promise as a clinical tool for clinicians and radiologists. We discuss the benefits and limitations of this approach
Age and Retinal Nerve Fiber Layer Thickness Measured by Spectral Domain Optical Coherence Tomography
Dietary docosahexaenoic acid supplementation modulates hippocampal development in the pemt-/- mouse
The development of fetal brain is influenced by nutrients such as docosahexaenoic acid (DHA, 22:6) and choline. Phosphatidylethanolamine-N-methyltransferase (PEMT) catalyzes the biosynthesis of phosphatidylcholine from phosphatidylethanolamine enriched in DHA and many humans have functional genetic polymorphisms in the PEMT gene. Previously, it was reported that Pemt-/- mice have altered hippocampal development. The present study explores whether abnormal phosphatidylcholine biosynthesis causes altered incorporation of DHA into membranes, thereby influencing brain development, and determines whether supplemental dietary DHA can reverse some of these changes. Pregnant C57BL/6 wild type (WT) and Pemt-/- mice were fed a control diet, or a diet supplemented with 3 g/kg of DHA, from gestational day 11 to 17. Brains from embryonic day 17 fetuses derived from Pemt-/- dams fed the control diet had 25-50% less phospholipid-DHA as compared with WT (p < 0.05). Also, they had 60% more neural progenitor cell proliferation (p < 0.05), 60% more neuronal apoptosis (p < 0.01), and 30% less calretinin expression (p < 0.05; a marker of neuronal differentiation) in the hippocampus compared with WT. The DHA-supplemented diet increased fetal brain Pemt-/- phospholipid-DHA to WT levels, and abrogated the neural progenitor cell proliferation and apoptosis differences. Although this diet did not change proliferation in the WT group, it halved the rate of apoptosis (p < 0.05). In both genotypes, the DHA-supplemented diet increased calretinin expression 2-fold (p < 0.05). These results suggest that the changes in hippocampal development in the Pemt-/- mouse could be mediated by altered DHA incorporation into membrane phospholipids, and that maternal dietary DHA can influence fetal brain development
Non-destructive seed detection in mandarins: comparison of automatic threshold methods FLASH and COMSPIRA MRIs
Here, we review different methods for non-destructive horticultural produce size determination, focusing on electronic technologies capable of measuring fruit volume. The usefulness of produce size estimation is justified and a comprehensive classification system of the existing electronic techniques to determine dimensional size is proposed. The different systems identified are compared in terms of their versatility, precision and throughput. There is general agreement in considering that online measurement of axes, perimeter and projected area has now been achieved. Nevertheless, rapid and accurate volume determination of irregular-shaped produce, as needed for density sorting, has only become available in the past few years. An important application of density measurement is soluble solids content (SSC) sorting. If the range of SSC in the batch is narrow and a large number of classes are desired, accurate volume determination becomes important. A good alternative for fruit three-dimensional surface reconstruction, from which volume and surface area can be computed, is the combination of height profiles from a range sensor with a two-dimensional object image boundary from a solid-state camera (brightness image) or from the range sensor itself (intensity image). However, one of the most promising technologies in this field is 3-D multispectral scanning, which combines multispectral data with 3-D surface reconstruction
A systematic molecular and pharmacologic evaluation of AKT inhibitors reveals new insight into their biological activity.
Background AKT, a critical effector of the phosphoinositide 3-kinase (PI3K) signalling cascade, is an intensely pursued therapeutic target in oncology. Two distinct classes of AKT inhibitors have been in clinical development, ATP-competitive and allosteric. Class-specific differences in drug activity are likely the result of differential structural and conformational requirements governing efficient target binding, which ultimately determine isoform-specific potency, selectivity profiles and activity against clinically relevant AKT mutant variants.Methods We have carried out a systematic evaluation of clinical AKT inhibitors using in vitro pharmacology, molecular profiling and biochemical assays together with structural modelling to better understand the context of drug-specific and drug-class-specific cell-killing activity.Results Our data demonstrate clear differences between ATP-competitive and allosteric AKT inhibitors, including differential effects on non-catalytic activity as measured by a novel functional readout. Surprisingly, we found that some mutations can cause drug resistance in an isoform-selective manner despite high structural conservation across AKT isoforms. Finally, we have derived drug-class-specific phosphoproteomic signatures and used them to identify effective drug combinations.Conclusions These findings illustrate the utility of individual AKT inhibitors, both as drugs and as chemical probes, and the benefit of AKT inhibitor pharmacological diversity in providing a repertoire of context-specific therapeutic options
Effects of Age on Optical Coherence Tomography Measurements of Healthy Retinal Nerve Fiber Layer, Macula, and Optic Nerve Head
Purpose—To determine the effects of age on global and sectoral peripapillary retinal nerve fiber
layer (RNFL), macular thicknesses and optic nerve head (ONH) parameters in healthy subjects using
optical coherence tomography (OCT).
Design—Retrospective, cross-sectional observational study.
Participants—226 eyes from 124 healthy subjects were included.
Methods—Healthy subjects were scanned using the Fast RNFL, Fast Macula, and Fast ONH scan
patterns on a Stratus OCT. All global and sectoral RNFL and macular parameters and global ONH
parameters were modeled in terms of age using linear mixed effects models. Normalized slopes were
also calculated by dividing the slopes by the mean value of the OCT parameter for inter-parameter
comparison.
Main Outcome Measures—Slope of each OCT parameter across age.
Results—All global and sectoral RNFL thickness parameters statistically significantly decreased
with increasing age, except for the temporal quadrant and clock hours 8-10, which were not statistically different from a slope of zero. Highest absolute slopes were in the inferior and superior
quadrant RNFL and clock hour 1 (superior nasal). Normalized slopes showed similar rate in all sectors
except for the temporal clock hours (8-10). All macular thickness parameters statistically
significantly decreased with increasing age, except for the central fovea sector, which had a slight
positive slope that was not statistically significant. The nasal outer sector had the greatest absolute
slope. Normalized macular slope in the outer ring was similar to the normalized slopes in the RNFL.
Normalized inner ring had shallower slope than the outer ring with similar rate in all quadrants. Disc
area remained nearly constant across the ages, but cup area increased and rim area decreased with
age, both of which were statistically significant.
Conclusions—Global and regional changes due to the effects of age on RNFL, macula and ONH
OCT measurements should be considered when assessing eyes over time.National Institutes of Health (U.S.) (R01-EY13178-09)National Institutes of Health (U.S.) (R01-EY11289-23)National Institutes of Health (U.S.) (P30-EY008098
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