Application of dimensional analysis and group theory to the solution of ordinary and partial differential equations Final report, 17 Jan. 1966 - 16 Jan. 1967

Dimensional analysis and group theory methods of solving ordinary and partial differential equation

Legacy and shockwaves: A spatial analysis of strengthening resilience of the power grid in Connecticut

Grid resilience and reliability are pivotal in the transition to low and zero carbon energy systems. Tree-trimming operations (TTOs) have become a pivotal tool for increasing the resilience power grids, especially in highly forested regions. Building on recent literature, we aim at assessing the temporal and spatial extents of the benefits that TTOs produce on the grid from three perspectives: the frequency, extent, and duration of outages. We use a unique dataset provided by Eversource Energy, New England's largest utility company, with outage events from 2009 to 2015. We employ spatial econometrics to investigate both the legacy and spatial extent of TTOs. Our results show TTOs benefits occur for all three metrics for at least 4 years, and benefits spillover to up to 2 km throughout the treated areas, with significant spatial spillovers across the state greater than direct effects. Implications lead to supporting TTOs as part of the hardening policies for utility companies, especially as home-based activities increase in importance in a post-COVID19 world

A guidance and control assessment of three vertical landing options for RLV

The National Aeronautics and Space Administration is considering a vertical lander as a candidate concept for a single-stage-to-orbit reusable launch vehicle (RLV). Three strategies for guiding and controlling the inversion of a reentering RLV from a nose-first attitude to a vertical landing attitude are suggested. Each option is simulated from a common reentry state to touchdown, using a common guidance algorithm and different controllers. Results demonstrate the characteristics that typify and distinguish each concept and help to identify peculiar problems, level of guidance and control sophistication required, feasibility concerns, and areas in which stringent subsystem requirements will be imposed by guidance and control

Determination of the Thickness and Dielectric Constant of a Dielectric Slab Backed by Free-Space or a Conductor through Inversion of the Reflection Coefficient of a Rectangular Waveguide Probe

Evaluation of thickness and material properties of coatings and dielectric slabs is an important practical issue. Microwave nondestructive testing techniques, using open-ended rectangular waveguide and coaxial probes have shown great potential for this purpose. However, to evaluate one parameter requires that the other be known a priori. This paper discusses the use of a relatively efficient method for evaluating both parameters simultaneously from measurements of the reflection coefficient of a test material. Results of two cases as well as a brief discussion of the limitations of the technique are provided in this paper

Low Soluble Syndecan-1 Precedes Preeclampsia

Introduction Syndecan-1 (Sdc1; CD138) is a major transmembrane heparan sulfate proteoglycan expressed on the extracellular, luminal surface of epithelial cells and syncytiotrophoblast, thus comprising a major component of the glycocalyx of these cells. The "soluble" (shed) form of Sdc1 has paracrine and autocrine functions and is normally produced in a regulated fashion. We compared plasma soluble Sdc1 concentrations, in relation to placental Sdc1 expression, in uncomplicated (control) and preeclamptic pregnancies. Methods We evaluated soluble Sdc1 across uncomplicated pregnancy, and between preeclamptic, gestational hypertensive and control patients at mid-pregnancy (20 weeks) and 3rd trimester by ELISA. Placental expression level of Sdc1 was compared between groups in relation to pre-delivery plasma soluble Sdc1. Participants were recruited from Magee-Womens Hospital. Results In uncomplicated pregnancy, plasma soluble Sdc1 rose significantly in the 1st trimester, and reached an approximate 50-fold increase at term compared to post pregnancy levels. Soluble Sdc1 was lower at mid-pregnancy in women who later developed preeclampsia (P<0.05), but not gestational hypertension, compared to controls, and remained lower at late pregnancy in preeclampsia (P<0.01) compared to controls. Sdc1 was prominently expressed on syncytiotrophoblast of microvilli. Syncytiotrophoblast Sdc1 immunostaining intensities, and mRNA content in villous homogenates, were lower in preeclampsia vs. controls (P<0.05). Soluble Sdc1 and Sdc1 immunostaining scores were inversely associated with systolic blood pressures, and positively correlated with infant birth weight percentile

Measurements of actinides in soil, sediments, water and vegetation in Northern New Mexico

This study was undertaken during 1991 - 1998 to identify the origin of plutonium uranium in northern New Mexico Rio Grande and tributary stream sediments. Isotopic fingerprinting techniques help distinguish radioactivity from Los Alamos National Laboratory (LANL) and from global fallout or natural sources. The geographic area covered by the study extended from the headwaters of the Rio Grande in southern Colorado to Elephant Butte Reservoir in southern New Mexico. Over 100 samples of stream channel and reservoir bottom sediments were analyzed for the atom ratios of plutonium and uranium isotopes using thermal ionization mass spectrometry (TIMS). Comparison of these ratios against those for fallout or natural sources allowed for quantification of the Laboratory impact. Of the seven major drainages crossing LANL, movement of LANL plutonium into the Rio Grande can only be traced via Los Alamos Canyon. The majority of sampled locations within and adjacent to LANL have little or no input of plutonium from the Laboratory. Samples collected upstream and distant to L A N show an average (+ s.d.) fallout 240Pu/239Pauto m ratio of 0.169 + 0.012, consistent with published worldwide global fallout values. These regional background ratios differ significantly from the 240Pu/239Pu atom ratio of 0.015 that is representative of LANL-derived plutonium entering the Rio Grande at Los Alamos Canyon. Mixing calculations of these sources indicate that the largest proportion (60% to 90%) of the plutonium in the Rio Grande sediments is from global atmospheric fallout, with an average of about 25% from the Laboratory. The LANL plutonium is identifiable intermittently along the 35-km reach of the Rio Grande to Cochiti Reservoir. The source of the LANL-derived plutonium in the Rio Grande was traced primarily to pre-1960 discharges of liquid effluents into a canyon bottom at a distance approximately 20 km upstream of the river. Plutonium levels decline exponentially with distance downstream after mixing with cleaner sediments, yet the LANL isotopic fingerprint remains distinct for at least 55 km from the effluent source. Plutonium isotopes in Rio Grande and Pajarito Plateau sediments are not at levels known to adversely affect public health. Activities of 239+240pwui thin this sample set ranged from 0.001- 0.046 pCUg in the Rio Grande to 3.7 pCi/g near the effluent discharge point. Levels in the Rio Grande are usually more than 1000 times. lower than prescribed cleanup standards. Uranium in stream and reservoir sediments is predominantly within natural concentration ranges and is of natural uranium isotopic composition. None of the sediments from the Rio Grande show identifiable Laboratory uranium, using the isotopic ratios. These results suggest that the mass of Laboratory-derived uranium entering the Rio Grande is small relative to the natural load carried with river sediments

Evolution of a Canada Basin ice-ocean boundary layer and mixed layer across a developing thermodynamically forced marginal ice zone

A comprehensive set of autonomous, ice-ocean measurements were collected across the Canada Basin to study the summer evolution of the ice-ocean boundary layer (IOBL) and ocean mixed layer (OML). Evaluation of local heat and freshwater balances and associated turbulent forcing reveals that melt ponds (MPs) strongly influence the summer IOBL-OML evolution. Areal expansion of MPs in mid-June start the upper ocean evolution resulting in significant increases to ocean absorbed radiative flux (19 W m−2 in this study). Buoyancy provided by MP drainage shoals and freshens the IOBL resulting in a 39 MJ m−2 increase in heat storage in just 19 days (52% of the summer total). Following MP drainage, a near-surface fresh layer deepens through shear-forced mixing to form the summer mixed layer (sML). In late summer, basal melt increases due to stronger turbulent mixing in the thin sML and the expansion of open water areas due in part to wind-forced divergence of the sea ice. Thermal heterogeneities in the marginal ice zone (MIZ) upper ocean led to large ocean-to-ice heat fluxes (100–200 W m−2) and enhanced basal ice melt (3–6 cm d−1), well away from the ice edge. Calculation of the upper ocean heat budget shows that local radiative heat input accounted for at least 89% of the observed latent heat losses and heat storage (partitioned 0.77/0.23). These results suggest that the extensive area of deteriorating sea ice observed away from the ice edge during the 2014 season, termed the “thermodynamically forced MIZ,” was driven primarily by local shortwave radiative forcing

Colostomy as a bridge to definitive pediatric surgical care: A sub-Saharan African experience

Available data, however, points to a wide variety of surgical conditions, with the majority falling into three major diagnostic categories, injuries, congenital anomalies, and surgical infections.1 In Africa, children constitute more than half the population.2 Despite high patient volume, very few dedicated pediatric surgeons are available, with only one pediatric surgeon to approximately two million children in Africa, compared with 1:100,000 in North America.3 Owing to this dearth of pediatric surgical workforce, surgical disease in children is not often managed, and if managed, is predominantly managed by a general surgeon who may lack familiarity with complex pediatric surgical procedures. There is little information in the literature regarding the clinical indications for pediatric patients receiving colostomies, complications associated with colostomies, and colostomy reversal rates in sub-Saharan Africa. [...]the aim of this study is to describe the characteristics and outcomes of patients receiving colostomies in a sub-Saharan African setting. [...]during our study period, there were only four patients who returned for reversal of their colostomy, with two colostomy takedowns and two pull-through procedures, with an average of 261.3 ± 288.1 days till reversal (range 36 to 654 days)

Community Impacts of Prosopis Juliflora Invasion: Biogeographic and Congeneric Comparisons

We coordinated biogeographical comparisons of the impacts of an exotic invasive tree in its native and non-native ranges with a congeneric comparison in the non-native range. Prosopis juliflora is taxonomically complicated and with P. pallida forms the P. juliflora complex. Thus we sampled P. juliflora in its native Venezuela, and also located two field sites in Peru, the native range of Prosopis pallida. Canopies of Prosopis juliflora, a native of the New World but an invader in many other regions, had facilitative effects on the diversity of other species in its native Venezuela, and P. pallida had both negative and positive effects depending on the year, (overall neutral effects) in its native Peru. However, in India and Hawaii, USA, where P. juliflora is an aggressive invader, canopy effects were consistently and strongly negative on species richness. Prosopis cineraria, a native to India, had much weaker effects on species richness in India than P. juliflora. We carried out multiple congeneric comparisons between P. juliflora and P. cineraria, and found that soil from the rhizosphere of P. juliflora had higher extractable phosphorus, soluble salts and total phenolics than P. cineraria rhizosphere soils. Experimentally applied P. juliflora litter caused far greater mortality of native Indian species than litter from P. cineraria. Prosopis juliflora leaf leachate had neutral to negative effects on root growth of three common crop species of north-west India whereas P. cineraria leaf leachate had positive effects. Prosopis juliflora leaf leachate also had higher concentrations of total phenolics and L-tryptophan than P. cineraria, suggesting a potential allelopathic mechanism for the congeneric differences. Our results also suggest the possibility of regional evolutionary trajectories among competitors and that recent mixing of species from different trajectories has the potential to disrupt evolved interactions among native species