Investigation of conductive thermal control coatings by a contactless method in vacuo

A technique for determining the conductance per unit area of thermal control coatings for electrostatically clean spacecraft is described. In order to simulate orbital conditions more closely, current-density-voltage (j-V) curves are obtained by a contactless method in which the paint on an aluminum substrate is the anode of a vacuum diode configuration with a tungsten filament cathode. Conductances per unit area which satisfy the International Sun Earth Explorer (ISEE) requirement were observed on black paints containing carbon and in white and green paints filled with zinc oxide which were fired in order to induce defect conductivity. Because of surface effects and the nonhomogeneous nature of paints, large discrepancies were found between measurements with the contactless method and measurements employing metallic contacts, particularly at low current densities. Therefore, measurements with metallic contacts are considered to be of questionable value in deciding the suitability of coatings for electrostatic charge control

Enhancement and suppression effects resulting from information structuring in sentences

Information structuring through the use of cleft sentences increases the processing efficiency of references to elements within the scope of focus. Furthermore, there is evidence that putting certain types of emphasis on individual words not only enhances their subsequent processing, but also protects these words from becoming suppressed in the wake of subsequent information, suggesting mechanisms of enhancement and suppression. In Experiment 1, we showed that clefted constructions facilitate the integration of subsequent sentences that make reference to elements within the scope of focus, and that they decrease the efficiency with reference to elements outside of the scope of focus. In Experiment 2, using an auditory text-change-detection paradigm, we showed that focus has similar effects on the strength of memory representations. These results add to the evidence for enhancement and suppression as mechanisms of sentence processing and clarify that the effects occur within sentences having a marked focus structure

Background and summary: a new focus on groundwater-seawater interactions

Water and chemical fluxes across the sea floor provide an important linkage between terrestrial and marine environments. Oceanographers recognize that these fluxes may act as a source of nutrients or other harmful contaminants to marine systems (e.g. Johannes, 1980; Valiela et al., 1990). These fluxes may also act as a beneficial source of freshwater for coastal marine estuaries that require relatively low salinities. Hydrologists and hydrogeologists recognize that fluxes across the sea floor comprise an important part of the water balance for coastal aquifers. Most fresh groundwater discharge to the ocean is derived from terrestrial aquifer recharge. Management of coastal aquifers requires careful estimates of recharge and other hydrological components, such as groundwater discharge. These estimates are commonly combined into a comprehensive water budget to evaluate how much groundwater might be available for municipal uses and whether saltwater intrusion may be a potential concern. Excessive groundwater withdrawals can cause saltwater intrusion by intercepting the seaward flux of freshwater that prevents saltwater from intruding a coastal aquifer. Quantitative estimates of fresh groundwater discharge toward the coast can provide a basis for determining safe withdrawal rates. Oceanographers, marine scientists, and those studying and managing saltwater intrusion in coastal aquifers, share a common goal of quantification and understanding of groundwater and seawater interactions. Submarine groundwater discharge, or SGD, has become a popular term in the literature for describing the flux of water across the sea floor. Burnett et al. (2003) specifically define SGD as the discharge of aquifer porewater across the sea floor and into the ocean. They define flow in the opposite direction as submarine groundwater recharge (SGR). SGR is the recharging flux of seawater into the aquifer. The presence of SGR does not necessarily indicate saltwater intrusion, which occurs when saline water moves into parts of the aquifer previously occupied by freshwater. A conceptual model of the types of flow patterns that are expected to exist in many coastal aquifers at the terrestrial–marine boundary is shown. Through a detailed field study, Kohout (1960) showed that as fresh groundwater flows seaward, it meets and mixes with saline groundwater before discharging into the ocean. Because of this mixing and subsequent discharge to the ocean, seawater is drawn into the aquifer to replace the saline groundwater that discharged to the ocean. Seawater drawn into the aquifer is sometimes referred to as recirculated seawater. Michael et al. (2005) suggest that the seasonality of terrestrial recharge may also act as a mechanism for recirculating seawater through a coastal aquifer. As the mixing zone moves landward and seaward in response to seasonal fluctuations in recharge, seawater may be drawn in and flushed out of the aquifer over the course of a year. SGD can also occur at the bottom of the open ocean, even in the absence of a terrestrial connection. Waves, tides, and ocean currents can create hydraulic gradients that pump seawater across the sea floor. Interest in groundwater–seawater interactions continues to receive a significant amount of attention in the literature. Saltwater intrusion, freshwater deliveries to marine estuaries, and nutrient loading are persistent problems of global importance. The problems are difficult to address, however, because of the elusive nature of SGD. Fortunately, the science is advancing. The journal Biogeochemistry, dedicated the entire November 2003 issue to the subject of SGD as did the journal Ground Water, in the December 2004 issue. Zektser & Dzhamalov (2007) released a comprehensive review on the subject of SGD and groundwater–seawater interactions in a new book: Submarine Groundwater. In their book, they suggest that SGD and related studies should be categorized into a new field called “Marine Hydrogeology”. The concentrated efforts of numerous researchers from a wide range of disciplines have led to substantial advancements in characterizing SGD, but there is still more work to be done

Preface

Water and chemical fluxes across the sea bottom provide an important linkage between terrestrial and marine environments. From the marine perspective, these water fluxes, commonly referred to as submarine groundwater discharge (SGD), may contain elevated nutrient concentrations or high levels of other potentially harmful contaminants. Terrestrially derived SGD can also be an important source of freshwater for estuarine ecosystems that require relatively low salinities. For these reasons, the past decade has shown a rapid increase in the level of interest from estuary and marine scientists toward a better understanding of SGD. From the terrestrial perspective, SGD has also been a topic of interest to those studying saltwater intrusion and management of coastal aquifers. Saltwater intrusion studies commonly employ some form of a water balance method, whether through numerical modelling or volumetric calculations, to explain intrusion patterns and develop predictions and management plans. In developing a water balance for a coastal aquifer, estimates for all of the key components, including SGD, are synthesized. Although the motivation may be different depending on whether one works from the marine or terrestrial perspective, both groups have a common goal of obtaining accurate SGD estimate

Can your house keep you out of a nursing home?

We examine the impact of the accessibility of an older individual's house on her use of nursing home care. We link administrative data on the accessibility of all houses in the Netherlands to data on long-term care use of all older persons from 2011 to 2014. We find that older people living in more accessible houses are less likely to use nursing home care. The effects increase with age and are largest for individuals aged 90 or older. The effects are stronger for people with physical limitations than for persons with cognitive problems. We also provide suggestive evidence that older people living in more accessible houses substitute nursing home care by home care

Impact of Oxidation State on Reactivity and Selectivity Differences between Nickel(III) and Nickel(IV) Alkyl Complexes

Described is a systematic comparison of factors impacting the relative rates and selectivities of C(sp3)−C and C(sp3)−O bond‐forming reactions at high‐valent Ni as a function of oxidation state. Two Ni complexes are compared: a cationic octahedral NiIV complex ligated by tris(pyrazolyl)borate and a cationic octahedral NiIII complex ligated by tris(pyrazolyl)methane. Key features of reactivity/selectivity are revealed: 1) C(sp3)−C(sp2) bond‐forming reductive elimination occurs from both centers, but the NiIII complex reacts up to 300‐fold faster than the NiIV, depending on the reaction conditions. The relative reactivity is proposed to derive from ligand dissociation kinetics, which vary as a function of oxidation state and the presence/absence of visible light. 2) Upon the addition of acetate (AcO−), the NiIV complex exclusively undergoes C(sp3)−OAc bond formation, while the NiIII analogue forms the C(sp3)−C(sp2) coupled product selectively. This difference is rationalized based on the electrophilicity of the respective M−C(sp3) bonds, and thus their relative reactivity towards outer‐sphere SN2‐type bond‐forming reactions.The high point: This report describes a systematic comparison of factors impacting the relative rates and selectivities of C(sp3)−C and C(sp3)−O bond‐forming reactions at high‐valent Ni centers as a function of oxidation state (NiIII versus NiIV). Two Ni complexes are compared: a cationic octahedral NiIV complex ligated by tris(pyrazolyl)borate and a cationic octahedral NiIII complex ligated by tris(pyrazolyl)methane.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150547/1/anie201903638.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150547/2/anie201903638-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150547/3/anie201903638_am.pd

Can an Optical Plankton Counter Produce Reasonable Estimates of Zooplankton Abundance and Biovolume in Water With High Detritus?

The Optical Plankton Counter (OPC) has been used in oceanic and fresh waters to estimate zooplankton abundance and biovolume. However, it is not clear whether the OPC can produce accurate estimates of zooplankton abundance and biovolume in waters with high detritus. In order to test the capability of the OPC to estimate zooplankton abundance and biovolume in Chesapeake Bay, two sets of laboratory experiments were conducted using water with high detritus concentrations collected from the upper Choptank estuary of Chesapeake Bay and laboratory cultured Artemia. Our results suggest that the OPC is able to produce accurate estimates of zooplankton biovolume after correcting for the influence of background detritus in all the detritus concentrations used, but accurate estimates of zooplankton abundance only in water with background detritus \u3c100 particles l-1. The relationship between light attenuation and OPC background particle concentrations provides a useful way to estimate OPC background particle concentrations when direct OPC background particle measurements are not available. Light attenuation corrected OPC particle abundance and particle volume gave accurate estimates of zooplankton abundance and biovolume. However, the accuracy of the corrected OPC measurements by the estimated background particle concentrations was not as high as the corrected OPC measurements by the direct background particle measurements

Observed suppression of ozone formation at extremely high temperatures due to chemical and biophysical feedbacks

Ground level ozone concentrations ([O3]) typically show a direct linear relationship with surface air temperature. Three decades of California measurements provide evidence of a statistically significant change in the ozone-temperature slope (ΔmO3-T) under extremely high temperatures (> 312 K). This ΔmO3-T leads to a plateau or decrease in [O3], reflecting the diminished role of nitrogen oxide sequestration by peroxyacetyl nitrates and reduced biogenic isoprene emissions at high temperatures. Despite inclusion of these processes in global and regional chemistry-climate models, a statistically significant change in ΔmO3-T has not been noted in prior studies. Future climate projections suggest a more frequent and spatially widespread occurrence of this ΔmO3-T response, confounding predictions of extreme ozone events based on the historically observed linear relationship

A method for achieving reciprocity of funding in community-based participatory research

BACKGROUND: The St. Louis Komen Project was conceived to address disparities in breast cancer treatment and outcomes between African-American and White women in St. Louis, Missouri. Our goal was to apportion tasks and funding through a process to which all researcher partners had input and to which all could agree, thus eliminating institutionalized inequalities. METHODS: This paper describes the collaborative process and resulting division of responsibilities, determination of costs, and ultimate allocation of funds and resources, as well as the documentation employed to achieve funding reciprocity and equal accountability. RESULTS: Both communication and documentation are critical. Although the Memoranda of Understanding employed are not a panacea, they codify roles and expectations and promote trust. The process of developing financial transparency set the tone for subsequent steps in the research process. CONCLUSIONS: The exhaustive planning process and project-specific procedures developed by its partners have helped the project foster reciprocity, facilitate participation, and equitably distribute resources