The Potential for Public-Private Partnerships: Philanthropic Leaders Considering Housing as a Platform

Explores foundation leaders' approaches to housing as a platform for layering programs and services to improve quality of life, views on funding partnerships with the federal government, and suggestions for targeted collaborations. Includes case studies

Modelling a single phase voltage controlled rectifier using Laplace transforms

The development of a 20 kHz, AC power system by NASA for large space projects has spurred a need to develop models for the equipment which will be used on these single phase systems. To date, models for the AC source (i.e., inverters) have been developed. It is the intent of this paper to develop a method to model the single phase voltage controlled rectifiers which will be attached to the AC power grid as an interface for connected loads. A modified version of EPRI's HARMFLO program is used as the shell for these models. The results obtained from the model developed in this paper are quite adequate for the analysis of problems such as voltage resonance. The unique technique presented in this paper uses the Laplace transforms to determine the harmonic content of the load current of the rectifier rather than a curve fitting technique. Laplace transforms yield the coefficient of the differential equations which model the line current to the rectifier directly

Development of a single-phase harmonic power flow program to study the 20 kHz AC power system for large spacecraft

The development of software is described to aid in design and analysis of AC power systems for large spacecraft. The algorithm is an important version of harmonic power flow program, HARMFLO, used for the study of AC power quality. The new program is applicable to three-phase systems typified by terrestrial power systems, and single-phase systems characteristic of space power systems. The modified HARMFLO accommodates system operating frequencies ranging from terrestrial 60 Hz to and beyond aerospace 20 kHz, and can handle both source and load-end harmonic distortions. Comparison of simulation and test results of a representative spacecraft power system shows a satisfactory correlation. Recommendations are made for the direction of future improvements to the software, to enhance its usefulness to power system designer and analysts

Neutral and Cationic Bis-Chelate Monoorganosilicon(IV) Complexes of 1-Hydroxy-2-pyridinone

A series of spirocyclic monoorganosilicon compounds of the form RSi(OPO)2Cl [R = phenyl (1); p-tolyl (2); benzyl (3); Me (4); tBu (5); thexyl (6)] (OPO = 1-oxo-2-pyridinone) was synthesized and characterized by 1H , 13C, and 29Si NMR spectroscopy, X-ray crystallography, and elemental analysis. In the solid state, complexes 1, 2, and 3 are neutral and possess cis-OPO ligands in an octahedral arrangement, and complexes 4, 5, and 6 are cationic and possess effectively trans­-OPO ligands in nearly ideal square pyramidal geometries along the Berry-pseudorotation coordinate. In 4-6, chloride dissociation is attributed to the additive effect of multiple intermolecular C—H∙∙∙Cl interactions in their crystals. In DMSO-d6 solution, compounds 1-6 form cationic hexacoordinate DMSO adducts with trans-OPO ligands, all of which undergo dynamic isomerization with energy barriers of ~18-19 kcal/mol. Compounds with better leaving groups, (p-tolyl)Si(OPO)2X [X = I (7); X = triflate (8)], exhibit identical solution NMR spectra as 2, supporting anion dissociation in each. The fluoride derivatives RSi(OPO)2F [R = benzyl (9); Me (10)] exhibit hexacoordinate geometries with cis­-OPO ligands in the solid state and exhibit dynamic isomerization in solution. Overall, these studies indicate, in both the solid and solution states, that the trans-OPO ligand arrangement is favored when anions are dissociated and a cis­-OPO ligand arrangement when anions are coordinated

Turbofan aft duct suppressor study program listing and user's guide

A description of the structure of the Annular Flow Duct Program (AFDP) for the calculation of acoustic suppression due to treatment in a finite length annular duct carrying sheared flow is presented. Although most appropriate for engine exhaust ducts, this program can be used to study sound propagation in any duct that maintains annular geometry over a considerable length of the duct. The program is based on the modal analysis of sound propagation in ducts with axial segments of different wall impedances. For specified duct geometry, wall impedance, flow and acoustic conditions in the duct (including mode amplitude distribution of the source) and duct termination reflection characteristics, the program calculates the suppression due to the treatment in the duct. The presence of forward and backward traveling modes in the duct due to the reflection and redistribution of modes at segment interfaces and duct end terminations are taken into account in the calculations. The effects of thin wall boundary layers (with a linear or mean flow velocity profile) on the acoustic propagation are also included in the program. A functional description of the major subroutines is included and a sample run is provided with an explanation of the output

Development of an analytical tool to study power quality of AC power systems for large spacecraft

A harmonic power flow program applicable to space power systems with sources of harmonic distortion is described. The algorithm is a modification of the Electric Power Research Institute's HARMFLO program which assumes a three phase, balanced, AC system with loads of harmonic distortion. The modified power flow program can be used with single phase, AC systems. Early results indicate that the required modifications and the models developed are quite adequate for the analysis of a 20 kHz testbed built by General Dynamics Corporation. This is demonstrated by the acceptable correlation of present results with published data. Although the results are not exact, the discrepancies are relatively small

In situ TEM study of twin boundary migration in sub-micron Be fibers

Deformation twinning in hexagonal crystals is often considered as a way to palliate the lack of independent slip systems. This mechanism might be either exacerbated or shut down in small-scale crystals whose mechanical behavior can significantly deviate from bulk materials. Here, we show that sub-micron beryllium fibers initially free of dislocation and tensile tested in-situ in a transmission electron microscope (TEM) deform by a $\{ 10\bar{1}2 \}$ $\langle 10\bar{1}1 \rangle$ twin thickening. The propagation speed of the twin boundary seems to be entirely controlled by the nucleation of twinning dislocations directly from the surface. The shear produced is in agreement with the repeated lateral motion of twinning dislocations. We demonstrate that the activation volume ($V$) associated with the twin boundary propagation can be retrieved from the measure of the twin boundary speed as the stress decreases as in a classical relaxation mechanical test. The value of $V \approx 8.3 \pm 3.3 \times 10^{-29}m^3$ is comparable to the value expected from surface nucleation.Comment: 13 pages, 9 figure

Buoyancy-driven inflow to a relic cold core: the gas belt in radio galaxy 3C 386

We report measurements from an XMM-Newton observation of the low-excitation radio galaxy 3C 386. The study focusses on an X-ray-emitting gas belt, which lies between and orthogonal to the radio lobes of 3C 386 and has a mean temperature of $0.94\pm0.05$ keV, cooler than the extended group atmosphere. The gas in the belt shows temperature structure with material closer to the surrounding medium being hotter than gas closer to the host galaxy. We suggest that this gas belt involves a `buoyancy-driven inflow' of part of the group-gas atmosphere where the buoyant rise of the radio lobes through the ambient medium has directed an inflow towards the relic cold core of the group. Inverse-Compton emission from the radio lobes is detected at a level consistent with a slight suppression of the magnetic field below the equipartition value.Comment: 11 pages, 10 figures, accepted for publication in MNRA

Pharmacological and non-pharmacological treatments for the Neonatal Abstinence Syndrome (NAS).

Neonatal abstinence syndrome is defined by signs and symptoms of withdrawal that infants develop after intrauterine maternal drug exposure. All infants with documented in utero opioid exposure, or a high pre-test probability of exposure should have monitoring with a standard assessment instrument such as a Finnegan Score. A Finnegan score of \u3e8 is suggestive of opioid exposure, even in the absence of declared use during pregnancy. At least half of infants in most locales can be treated without the use of pharmacologic means. For this reason, symptom scores will drive the decision for pharmacologic therapy. Nevertheless, all infants, regardless of initial manifestations, should be first be managed with non-pharmacologic approaches which in turn, should not be considered as the sole alternative to drug therapy, but rather, as the base upon which all patients are treated. Those who continue to have symptoms despite supportive care should be pharmacologically treated, which in the most severe cases, is life-saving