854 research outputs found
Methods for Evaluating Innovative Health Programs (EIHP): A Multi-Country Study
Designed as a global research initiative, the EIHP project aims at adding to the evidence base of health interventions that have the potential to improve health outcomes in Africa and Asia. The project focuses on rigorous, quantitative evaluations of innovative local initiatives that address the Millennium Development Goals for health: reductions in child and maternal mortality and communicable diseases. This overview brings together the outcomes and lessons from the project for evaluation methods. It draws together the methodological implications of carrying out impact evaluations under very different settings and emphasizes the need to build in evaluations in project designs.Millennium Development Goals; child and maternal health; communicable diseases; impact evaluation; capacity building; Asia; Africa; Latin America
Evaluating Innovative Health Programs: Lessons for Health Policy
The Global Development Network’s (GDN) project “Evaluating Innovative Health Programs” (EIHP), funded by the Bill & Melinda Gates Foundation, seeks to inform policy on the effectiveness of health solutions that have the potential to improve health outcomes in developing countries. It evaluates the impact of nineteen programs from across developing and transition countries that focus on the health-related Millennium Development Goals (MDGs) of reducing child and maternal mortality, and halting and reversing the trend of communicable diseases such as HIV/AIDS, malaria and other diseases. The policy implications of the diverse set of interventions are distinguished between programs that involved earmarking resources, changing incentives, and developing innovative methods of health care delivery.Millennium Development Goals; child and maternal health; communicable diseases; impact evaluation; capacity building; Asia; Africa; Latin America
Alien Registration- Thomas, Muriel (Waterville, Kennebec County)
https://digitalmaine.com/alien_docs/15077/thumbnail.jp
Multidimensional Tests of Thermal Protection Materials in the Arcjet Test Facility
Many thermal protection system materials used for spacecraft heatshields have anisotropic thermal properties, causing them to display significantly different thermal characteristics in different directions, when subjected to a heating environment during flight or arcjet tests. This paper investigates the effects of sidewall heating coupled with anisotropic thermal properties of thermal protection materials in the arcjet environment. Phenolic Impregnated Carbon Ablator (PICA) and LI-2200 materials (the insulation material of Shuttle tiles) were used for this study. First, conduction-based thermal response simulations were carried out, using the Marc.Mentat finite element solver, to study the effects of sidewall heating on PICA arcjet coupons. The simulation showed that sidewall heating plays a significant role in thermal response of these models. Arcjet tests at the Aerodynamic Heating Facility (AHF) at NASA Ames Research Center were performed later on instrumented coupons to obtain temperature history at sidewall and various radial locations. The details of instrumentation and experimental technique are the prime focus of this paper. The results obtained from testing confirmed that sidewall heating plays a significant role in thermal response of these models. The test results were later used to verify the two-dimensional ablation, thermal response, and sizing program, TITAN. The test data and model predictions were found to be in excellent agreemen
Hopf bifurcations to quasi-periodic solutions for the two-dimensional plane Poiseuille flow
This paper studies various Hopf bifurcations in the two-dimensional plane
Poiseuille problem. For several values of the wavenumber , we obtain
the branch of periodic flows which are born at the Hopf bifurcation of the
laminar flow. It is known that, taking , the branch of periodic
solutions has several Hopf bifurcations to quasi-periodic orbits. For the first
bifurcation, previous calculations seem to indicate that the bifurcating
quasi-periodic flows are stable and go backwards with respect to the Reynolds
number, . By improving the precision of previous works we find that the
bifurcating flows are unstable and go forward with respect to . We have
also analysed the second Hopf bifurcation of periodic orbits for several
, to find again quasi-periodic solutions with increasing . In this
case the bifurcated solutions are stable to superharmonic disturbances for
up to another new Hopf bifurcation to a family of stable 3-tori. The proposed
numerical scheme is based on a full numerical integration of the Navier-Stokes
equations, together with a division by 3 of their total dimension, and the use
of a pseudo-Newton method on suitable Poincar\'e sections. The most intensive
part of the computations has been performed in parallel. We believe that this
methodology can also be applied to similar problems.Comment: 23 pages, 16 figure
Genome analysis of Clostridium difficile PCR ribotype 014 lineage in Australian pigs and humans reveals a diverse genetic repertoire and signatures of long-range interspecies transmission
Clostridium difficile PCR ribotype (RT) 014 is well-established in both human and porcine populations in Australia, raising the possibility that C. difficile infection (CDI) may have a zoonotic or foodborne etiology. Here, whole genome sequencing and high-resolution core genome phylogenetics were performed on a contemporaneous collection of 40 Australian RT014 isolates of human and porcine origin. Phylogenies based on MLST (7 loci, STs 2, 13, and 49) and core orthologous genes (1260 loci) showed clustering of human and porcine strains indicative of very recent shared ancestry. Core genome single nucleotide variant (SNV) analysis found 42 % of human strains showed a clonal relationship (separated by ≤ 2 SNVs in their core genome) with one or more porcine strains, consistent with recent inter-host transmission. Clones were spread over a vast geographic area with 50 % of the human cases occurring without recent healthcare exposure. These findings suggest a persistent community reservoir with long-range dissemination, potentially due to agricultural recycling of piggery effluent. We also provide the first pan-genome analysis for this lineage, characterizing its resistome, prophage content, and in silico virulence potential. The RT014 is defined by a large “open” pan-genome (7587 genes) comprising a core genome of 2296 genes (30.3 % of the total gene repertoire) and an accessory genome of 5291 genes. Antimicrobial resistance genotypes and phenotypes varied across host populations and ST lineages and were characterized by resistance to tetracycline [tetM, tetA(P), tetB(P) and tetW], clindamycin/erythromycin (ermB), and aminoglycosides (aph3-III-Sat4A-ant6-Ia). Resistance was mediated by clinically important mobile genetic elements, most notably Tn6194 (harboring ermB) and a novel variant of Tn5397 (harboring tetM). Numerous clinically important prophages (Siphoviridae and Myoviridae) were identified as well as an uncommon accessory gene regulator locus (agr3). Conservation in the pathogenicity locus and S-layer correlated with ST affiliation, further extending the concept of clonal C. difficile lineages. This study provides novel insights on the genetic variability and strain relatedness of C. difficile RT014, a lineage of emerging One Health importance. Ongoing molecular and genomic surveillance of strains in humans, animals, food, and the environment is imperative to identify opportunities to reduce the overall CDI burden
Biologically Inspired Radiation Reflector
A thermal protection system (TPS) comprising a mixture of silicon carbide and SiOx that has been converted from Si that is present in a collection of diatom frustules and at least one diatom has quasi-periodic pore-to-pore separation distance d(p-p) in a selected range. Where a heat shield comprising the converted SiC/SiOx frustules receives radiation, associated with atmospheric (re)entry, a portion of this radiation is reflected so that radiation loading of the heat shield is reduced
Aerothermal Performance Constraints for Small Radius Leading Edges Operating at Hypervelocity
Small radius leading edges and nosetips were used to minimize wave drag in early hypervelocity vehicle concepts until further analysis demonstrated that extreme aerothermodynamic heating blunted the available thermal protection system materials. Recent studies indicate that ultra-high temperature composite (UHTC) materials are shape stable at temperatures approaching 3033 K and will be available for use as sharp leading edge components in the near future. Steady-state aerothermal performance constraints for UHTC components are presented in this paper to identify their non-ablating operational capability at altitudes from sea level to 90 km. An integrated design tool was developed to estimate these constraints. The tool couples aerothermodynamic heating with material response using commercial finite element analysis software and is capable of both steady-state and transient analysis. Performance during entry is analyzed by transient thermal analysis along the trajectory. The thermal load condition from the transient thermal analysis is used to estimate thermal stress. Applying the tool to UHTC materials shows that steady-state, non-ablating operation of a HfB2/SiC(A-7) (A-7) component is possible at velocities approaching Earth's circular orbital velocity of 7.9 km/s at altitudes approaching 70 km
Multiscale Modeling of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2: Application to Lattice Thermal Conductivity
We are developing a multiscale framework in computational modeling for the ultra high temperature ceramics (UHTC) ZrB2 and HfB2. These materials are characterized by high melting point, good strength, and reasonable oxidation resistance. They are candidate materials for a number of applications in extreme environments including sharp leading edges of hypersonic aircraft. In particular, we used a combination of ab initio methods, atomistic simulations and continuum computations to obtain insights into fundamental properties of these materials. Ab initio methods were used to compute basic structural, mechanical and thermal properties. From these results, a database was constructed to fit a Tersoff style interatomic potential suitable for atomistic simulations. These potentials were used to evaluate the lattice thermal conductivity of single crystals and the thermal resistance of simple grain boundaries. Finite element method (FEM) computations using atomistic results as inputs were performed with meshes constructed on SEM images thereby modeling the realistic microstructure. These continuum computations showed the reduction in thermal conductivity due to the grain boundary network
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