Water Resources Problems in Developing Countries

Resource /Energy Economics and Policy,

Localized exciton-polariton modes in dye-doped nanospheres: a quantum approach

We model a dye-doped polymeric nanosphere as an ensemble of quantum emitters and use it to investigate the localized exciton-polaritons supported by such a nanosphere. By determining the time evolution of the density matrix of the collective system, we explore how an incident laser field may cause transient optical field enhancement close to the surface of such nanoparticles. Our results provide further evidence that excitonic materials can be used to good effect in nanophotonics.Comment: 16 pages, 4 figure

Columbus City Attorney’s Office

From the non-stop pull of smart phones to overcommitted working parents, the average American worker is constantly plugged in and on the go. Such a cognitive overload can have dire consequences. These consequences include: memory and concentration problems; hostility and aggression; anxiety; and poor judgment (Smith, 2014). These effects of overload most certainly decrease the effectiveness of work productivity. To get the best out of their employees, restoring their wellbeing and re-engaging them at work should be of value to organizations across the country. Being mindful can increase wellbeing and engagement in activities along with improving concentration. Mindfulness also decreases stress and the likelihood of depression. One of the ways to increase mindfulness is through the practice of meditation (Benefits of Mindfulness, 2013). To use mindfulness and mediation in the corporate world, it can be administered through coaching. As organizational coaches work with employees, they can teach mindfulness meditation along with the use of wellbeing and positive assessments to create more engaged, focused employees and to help aid in leadership development. Assessments can be administered pre- and post- coaching experience to gauge effectiveness.https://fuse.franklin.edu/ss2014/1068/thumbnail.jp

Transport of trace metals in nearshore sediments

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution April 1985The focus of this thesis is on rates of transport of metals both across the sediment/water interface and within the sediment column of nearshore sediments. The early diagenesis of several first-row transition metals exhibiting a variety of behaviors in the ocean -- Mn, Fe, Co, Ni, and Cu -- has been studied intensively at a site in Buzzards Bay, Mass. By limiting the study to a single site, independent measurements over the seasonal cycle of the concentrations of the metals in pore water, of the pore water constituents important to metal cycling, and of particle and solute transport rates could be made at the same site. In addition, a direct, in situ study of the interaction of chemical and transport processes was undertaken using radiotracer techniques. Thus, the study emphasizes the mechanisms of metal cycling near the interface of nearshore sediments. Transport rates were estimated using excess 234Th distributions for particle transport, and pore water 222Rn deficit distributions for solute transport. Particle transport rates, modeled by analogy to Fickian diffusion, ranged from 7-80x10-8 cmz/sec, with excess 234Th reaching to 2-2.5 cm below the interface. There was a significant seasonal variation in rates, with a warm-season average of 40x10-8 cm2/sec and a cold-season average of 20x10-8 cm 2/sec. 234Th-derived mixing rates were applied to Mn distributions through a mass balance model of Mn cycling. It was found that a particulate flux due to bioturbation, from the net dissolved Mn removal layer to a net dissolved Mn production layer adjacent to the interface, was as large as 38% of net dissolved Mn production. Mixing of particulate Fe sulfides may have a similar importance for Fe cycling. Solute transport was estimated using measured 222Rn/ 226 Ra disequilibrium. The pore water 222Rn deficit could be explained using a model including vertical molecular diffusion and exchange with overlying seawater via exchange of pore water with bottom water in rapidly flushed burrows. Cores taken in all seasons could be split into three groups: (1) December through March: the 222Rn deficit was explained by vertical molecular diffusion alone; (2) early summer (June): irrigation affected the 222Rn profile to a depth of at least 20cm; (3) late summer/fall: irrigation was still important near the interface, affecting 222Rn profiles to depths of 10-12 cm. 222Rn deficits were adequately explained by an exchange parameter (a) which decreased exponentially with depth below the interface, but not by a constant-α model. Previous studies have explained irrigation using a constant exchange parameter throughout the irrigated layer. For comparative purposes, an α averaged over the upper 20 cm of the sediment column was calculated at the Buzzards Bay site: the range of depth-averaged α values found, 4-12x10-7 sec-1, is in agreement with values reported previously for a variety of nearshore sediments, using pore water Si02 as a tracer, of 1-20x10-7 sec-1. 222Rn-derived irrigation rates were applied to pore water Mn and Fe distributions. It was estimated that irrigation may contribute 20-40% of the dissolved Mn flux across the interface and about 20% of the dissolved Fe flux. Study of pore water metal chemistry at the Buzzards Bay site included measurements of pore water Mn and Fe during all seasons, and measurements of Co, Cu, and Ni in two cores: one under late winter conditions when the interface is most oxidizing; one when sulfate reduction was very important in the upper centimeter of the sediments. Fe regeneration sufficient to produce enrichments on water column particles was observed only during periods of summer and fall when the interface was reducing; otherwise, oxidation of Fe to insoluble Fe(III) limited Fe fluxes. Mn, Co, Cu, and Ni fluxes varied inversely to Fe fluxes; the primary control on fluxes of these elements was their limited solubility in reducing marine systems. The control was least important for Mn and Co; fluxes of Ni and Cu were significantly greater than zero only when sulfate reduction was unimportant in the upper centimeter of the sediment column. Fluxes of Mn were sufficient to affect the water column Mn distribution, with enrichments on water column particulates of up to 10,000 ppm inferred from calculated fluxes. Tentative estimates of the turnover time of dissolved Co, Cu, and Ni in the water column relative to the benthic flux indicated that the flux may be a significant contributor to the coastal Co cycle (turnover time = 1 yr), but is less likely to be important to Cu and Ni cycles (turnover times greater than 2 yrs). In situ radiotracer migration experiments were carried out at the Buzzards Bay site. 54Mn, 59Fe, 60Co, and 63Ni were released into the sediments at depths ranging from 2.5 to 7 cm below the interface. The order of mobilities was Mn»Fe>Co,Ni, which is similar to the solubility trend for these metals in reducing marine systems. 63Ni and 60Co were essentially particle-bound in these experiments; apparent diffusion coefficients calculated from their dispersion rates agreed with particle mixing rates from excess 234Th distributions. Solid:solution distribution coefficients were calculated from 54Mn dispersion and found to agree with directly measured values. The coefficient was approximately 15 (dpm/gm solid ÷ dpm/gm pore water) in the upper 0.5 cm and below 5 cm, and 5-10 from 0.5 to 5 cm. Distribution coefficients for 59Fe were approximately 120 below 0.5 cm. Although the trend of the distribution coefficients is clear, the quantitative results from these experiments are preliminary, in that the model used to explain metal ion dispersion, when applied to the nonreactive tracer, 36Cl, could only explain a portion of the 36Cl distribution. The agreement between calculated and directly measured s4Mn distribution coefficients, as well as the way the distributions of tracers varied as a function of apparent diffusion coefficient and time, provides evidence in favor of the adequacy of the model used.Financial support for parts of this work have come from: National Science Foundation grant #OCE-82-16425; Department of Commerce, NOAA, National Sea Grant College Program, under grant #NA80-AA-D-00077 (R/P/7); from the Coastal Research Center of the Woods Hole Oceanographic Institution; and from the WHOI Education Office

The New Deal, Race, and Home Ownership in the 1920s and 1930s

Many federal government housing policies began during the New Deal of the 1930s. Many claim that minorities benefited less from these policies than whites. We estimate the relationships between policies in the 1920s and 1930s and black and white home ownership in farm and nonfarm settings using a pseudo-panel of repeated cross-sections of households in 1920, 1930, and 1940 matched with policy measures in 460 state economic areas. The policies examined include FHA mortgage insurance, HOLC loan refinancing, state mortgage moratoria, farm loan programs, public housing, public works and relief, and payments to farmers to take land out of production.

Do Childhood Vaccines Have Non-Specific Effects on Mortality

A recent article by Kristensen et al. suggested that measles vaccine and bacille Calmette–Guérin (BCG) vaccine might\ud reduce mortality beyond what is expected simply from protection against measles and tuberculosis. Previous reviews of the potential effects of childhood vaccines on mortality have not considered methodological features of reviewed studies. Methodological considerations play an especially important role in observational assessments, in which selection factors for vaccination may be difficult to ascertain. We reviewed 782 English language articles on vaccines and childhood mortality and found only a few whose design met the criteria for methodological rigor. The data reviewed suggest that measles vaccine delivers its promised reduction in mortality, but there is insufficient evidence to suggest a mortality benefit above that caused by its effect on measles disease and its sequelae. Our review of the available data in the literature reinforces how difficult answering these considerations has been and how important study design will be in determining the effect of specific vaccines on all-cause mortality.\u

Assessing Short‐Term Impacts of Management Practices on N2O Emissions From Diverse Mediterranean Agricultural Ecosystems Using a Biogeochemical Model

Croplands are important sources of nitrous oxide (N2O) emissions. The lack of both long‐term field measurements and reliable methods for extrapolating these measurements has resulted in a large uncertainty in quantifying and mitigating N2O emissions from croplands. This is especially relevant in regions where cropping systems and farming management practices (FMPs) are diverse. In this study, a process‐based biogeochemical model, DeNitrification‐DeComposition (DNDC), was tested against N2O measurements from five cropping systems (alfalfa, wheat, lettuce, vineyards, and almond orchards) representing diverse environmental conditions and FMPs. The model tests indicated that DNDC was capable of predicting seasonal and annual total N2O emissions from these cropping systems, and the model\u27s performance was better than the Intergovernmental Panel on Climate Change emission factor approach. DNDC also captured the impacts on N2O emissions of nitrogen fertilization for wheat and lettuce, of stand age for alfalfa, as well as the spatial variability of N2O fluxes in vineyards and orchards. DNDC overestimated N2O fluxes following some heavy rainfall events. To reduce the biases of simulating N2O fluxes following heavy rainfall, studies should focus on clarifying mechanisms controlling impacts of environmental factors on denitrification. DNDC was then applied to assess the impacts on N2O emissions of FMPs, including tillage, fertilization, irrigation, and management of cover crops. The practices that can mitigate N2O emissions include reduced or no tillage, reduced N application rates, low‐volume irrigation, and cultivation of nonleguminous cover crops. This study demonstrates the necessity and potential of utilizing process‐based models to quantify N2O emissions from regions with highly diverse cropping systems

Tissue Inhibitor of Metalloproteinase–3 (TIMP-3) induces FAS dependent apoptosis in human vascular smooth muscle cells

Over expression of Tissue Inhibitor of Metalloproteinases-3 (TIMP-3) in vascular smooth muscle cells (VSMCs) induces apoptosis and reduces neointima formation occurring after saphenous vein interposition grafting or coronary stenting. In studies to address the mechanism of TIMP-3-driven apoptosis in human VSMCs we find that TIMP-3 increased activation of caspase-8 and apoptosis was inhibited by expression of Cytokine response modifier A (CrmA) and dominant negative FAS-Associated protein with Death Domain (FADD). TIMP-3 induced apoptosis did not cause mitochondrial depolarisation, increase activation of caspase-9 and was not inhibited by over-expression of B-cell Lymphoma 2 (Bcl2), indicating a mitochondrial independent/type-I death receptor pathway. TIMP-3 increased levels of the First Apoptosis Signal receptor (FAS) and depletion of FAS with shRNA showed TIMP-3-induced apoptosis was FAS dependent. TIMP-3 induced formation of the Death-Inducing Signalling Complex (DISC), as detected by immunoprecipitation and by immunofluorescence. Cellular-FADD-like IL-1 converting enzyme-Like Inhibitory Protein (c-FLIP) localised with FAS at the cell periphery in the absence of TIMP-3 and this localisation was lost on TIMP-3 expression with c-FLIP adopting a perinuclear localisation. Although TIMP-3 inhibited FAS shedding, this did not increase total surface levels of FAS but instead increased FAS levels within localised regions at the cell surface. A Disintegrin And Metalloproteinase 17 (ADAM17) is inhibited by TIMP-3 and depletion of ADAM17 with shRNA significantly decreased FAS shedding. However ADAM17 depletion did not induce apoptosis or replicate the effects of TIMP-3 by increasing localised clustering of cell surface FAS. ADAM17-depleted cells could activate caspase-3 when expressing levels of TIMP-3 that were otherwise sub-apoptotic, suggesting a partial role for ADAM17 mediated ectodomain shedding in TIMP-3 mediated apoptosis. We conclude that TIMP-3 induced apoptosis in VSMCs is highly dependent on FAS and is associated with changes in FAS and c-FLIP localisation, but is not solely dependent on shedding of the FAS ectodomain

Probabilistic structural mechanics research for parallel processing computers

Aerospace structures and spacecraft are a complex assemblage of structural components that are subjected to a variety of complex, cyclic, and transient loading conditions. Significant modeling uncertainties are present in these structures, in addition to the inherent randomness of material properties and loads. To properly account for these uncertainties in evaluating and assessing the reliability of these components and structures, probabilistic structural mechanics (PSM) procedures must be used. Much research has focused on basic theory development and the development of approximate analytic solution methods in random vibrations and structural reliability. Practical application of PSM methods was hampered by their computationally intense nature. Solution of PSM problems requires repeated analyses of structures that are often large, and exhibit nonlinear and/or dynamic response behavior. These methods are all inherently parallel and ideally suited to implementation on parallel processing computers. New hardware architectures and innovative control software and solution methodologies are needed to make solution of large scale PSM problems practical