Discovery of multi-anion antiperovskites X₆NFSn₂ (X = Ca, Sr) as promising thermoelectric materials by computational screening

The thermoelectric performance of existing perovskites lags far behind that of state-of-the-art thermoelectric materials such as SnSe. Despite halide perovskites showing promising thermoelectric properties, namely, high Seebeck coefficients and ultralow thermal conductivities, their thermoelectric performance is significantly restricted by low electrical conductivities. Here, we explore new multi-anion antiperovskites X6NFSn2 (X = Ca, Sr, and Ba) via B-site anion mutation in antiperovskite and global structure searches and demonstrate their phase stability by first-principles calculations. Ca6NFSn2 and Sr6NFSn2 exhibit decent Seebeck coefficients and ultralow lattice thermal conductivities (<1 W m−1 K−1). Notably, Ca6NFSn2 and Sr6NFSn2 show remarkably larger electrical conductivities compared to the halide perovskite CsSnI3. The combined superior electrical and thermal properties of Ca6NFSn2 and Sr6NFSn2 lead to high thermoelectric figures of merit (ZTs) of ∼1.9 and ∼2.3 at high temperatures. Our exploration of multi-anion antiperovskites X6NFSn2 (X = Ca, Sr) realizes the “phonon-glass, electron-crystal” concept within the antiperovskite structure

1982 custom rates for farm services in Missouri

"The custom rates reported in this guide were revised based on a statewide survey conducted in December 1982. Questionnaries were sent to farmers, agri-business firms, aerial applicators, and land improvement contractors known to be performing custom services. Rate data from the questionnaries were tabulated according to the most common rate reported, a simple average of all rates, and the range of the rates reported for the custom services being performed."--First page.Norlin A. Hein, Richard Rudel, David Schroder, and Kevin Walker (Department of Agricultural Economics), and Donald Pfost (Department of Agricultural Engineering, College of Agriculture)Revised 5/83/15

Liquidez y estrategias de cobranza en una Institución Educativa Privada, en contexto de Pandemia por COVID-19

The objective of this research was to determine to what extent liquidity and collection strategies are related in a private educational institution, in the context of a COVID 19 pandemic. The work was of a basic or pure type, with a quantitative approach, non-experimental design, transectional cut, and correlational level; the sample consisted of teaching and administrative collaborators. Through the respective normality analysis, a coefficient lower than the required 0.05 was obtained, so Pearson's parametric statistic was used. The results were: a correlation of (r=0.581) and a value of (p=0.006) between liquidity and collection strategies; a correlation coefficient (r=525) with a value of (p=0.014) between current assets and collection strategies; a correlation coefficient (r=508) with a value of (p=0.019) between short-term debts and collection strategies. It is concluded that there is a relationship between the proposed variables. It is recommended to strengthen the collection strategies in order to preserve the institution's liquidity.La presente investigación tuvo como objetivo determinar en qué medida se relaciona la liquidez y las estrategias de cobranza en una institución educativa privada, en contexto de pandemia por COVID 19, el trabajo fue de tipo básica o pura, el enfoque cuantitativo, de diseño no experimental, de corte transeccional, y de nivel correlacional; la muestra estuvo conformada por los colaboradores docentes y administrativos. A través del análisis de normalidad respectivo, se obtuvo un coeficiente menor al 0.05 requerido, por lo que se utilizó el estadígrafo paramétrico de Pearson. Los resultados fueron: una correlación de (r=0,581) y un valor de (p=0.006) entre la liquidez y las estrategias de cobranza; un coeficiente de correlación (r=525) con un valor de (p=0.014) entre el activo circulante y las estrategias de cobranza; un coeficiente de correlación (r=508) con un valor de (p=0.019) entre las deudas a corto plazo y las estrategias de cobranza. Se concluye en la existencia de la relación entre las variables propuestas. Se recomienda fortalecer las estrategias de cobranza con la finalidad de preservar la liquidez de la institución

A tale of two roads: Land tenure, poverty, and politics on the Guatemalan frontier

Agricultural frontiers are hot spots for the most dramatic land cover change in the history of humankind: forest conversion to agriculture. They are also areas of unusually rapid population growth and acute poverty, with scant access to public services and infrastructure. Although a large body of literature explores the determinants of land cover change on the frontier, one issue that has been largely unstudied is that of frontier political and socio-economic development. This paper reports on data from 28 communities along an agricultural frontier in a core conservation zone of the Maya Biosphere Reserve (MBR), where the predominant land tenure systems at the community level appear to be related not only to land use, but also to political organization and human development indicators. (c) 2005 Elsevier Ltd. All rights reserved

The neotropical reforestation hotspots : a biophysical and socioeconomic typology of contemporary forest expansion

Tropical reforestation is a significant component of global environmental change that is far less understood than tropical deforestation, despite having apparently increased widely in scale during recent decades. The regional contexts defining such reforestation have not been well described. They are likely to differ significantly from the geographical profiles outlined by site-specific observations that predominate in the literature. In response, this article determines the distribution, extent, and defining contexts of apparently spontaneous reforestation. It delineates regional ‘hotspots’ of significant net reforestation across Latin America and the Caribbean and defines a typology of these hotspots with reference to the biophysical and socioeconomic characteristics that unite and distinguish amongst them. Fifteen regional hotspots were identified on the basis of spatial criteria pertaining to the area, distribution, and rate of reforestation 2001–2014, observed using a custom continental MODIS satellite land-cover classification. Collectively, these hotspots cover 11% of Latin America and the Caribbean and they include 167,667.7 km2 of new forests. Comparisons with other remotely sensed estimates of reforestation indicate that these hotspots contain a significant amount of tropical reforestation, continentally and pantropically. The extent of reforestation as a proportion of its hotspot was relatively invariable (3–14%) given large disparities in hotspot areas and contexts. An ordination analysis defined a typology of five clusters, distinguished largely by their topographical roughness and related aspects of agro-ecological marginality, climate, population trends, and degree of urbanization: ‘Urban lowlands’, ‘Mountainous populated areas’, ‘Rural highlands’, ‘Rural humid lands’ and ‘Rural dry lands’. The typology highlights that a range of distinct, even oppositional regional biophysical, demographic, and agricultural contexts have equally given rise to significant, regional net reforestation, urging a concomitant diversification of forest transition science

Assaying Environmental Nickel Toxicity Using Model Nematodes

Although nickel exposure results in allergic reactions, respiratory conditions, and cancer in humans and rodents, the ramifications of excess nickel in the environment for animal and human health remain largely undescribed. Nickel and other cationic metals travel through waterways and bind to soils and sediments. To evaluate the potential toxic effects of nickel at environmental contaminant levels (8.9-7,600 µg Ni/g dry weight of sediment and 50-800 µg NiCl2/L of water), we conducted assays using two cosmopolitan nematodes, Caenorhabditis elegans and Pristionchus pacificus. We assayed the effects of both sediment-bound and aqueous nickel upon animal growth, developmental survival, lifespan, and fecundity. Uncontaminated sediments were collected from sites in the Midwestern United States and spiked with a range of nickel concentrations. We found that nickel-spiked sediment substantially impairs both survival from larval to adult stages and adult longevity in a concentration-dependent manner. Further, while aqueous nickel showed no adverse effects on either survivorship or longevity, we observed a significant decrease in fecundity, indicating that aqueous nickel could have a negative impact on nematode physiology. Intriguingly, C. elegans and P. pacificus exhibit similar, but not identical, responses to nickel exposure. Moreover, P. pacificus could be tested successfully in sediments inhospitable to C. elegans. Our results add to a growing body of literature documenting the impact of nickel on animal physiology, and suggest that environmental toxicological studies could gain an advantage by widening their repertoire of nematode species

Anti-filarial Activity of Antibiotic Therapy Is Due to Extensive Apoptosis after Wolbachia Depletion from Filarial Nematodes

Filarial nematodes maintain a mutualistic relationship with the endosymbiont Wolbachia. Depletion of Wolbachia produces profound defects in nematode development, fertility and viability and thus has great promise as a novel approach for treating filarial diseases. However, little is known concerning the basis for this mutualistic relationship. Here we demonstrate using whole mount confocal microscopy that an immediate response to Wolbachia depletion is extensive apoptosis in the adult germline, and in the somatic cells of the embryos, microfilariae and fourth-stage larvae (L4). Surprisingly, apoptosis occurs in the majority of embryonic cells that had not been infected prior to antibiotic treatment. In addition, no apoptosis occurs in the hypodermal chords, which are populated with large numbers of Wolbachia, although disruption of the hypodermal cytoskeleton occurs following their depletion. Thus, the induction of apoptosis upon Wolbachia depletion is non-cell autonomous and suggests the involvement of factors originating from Wolbachia in the hypodermal chords. The pattern of apoptosis correlates closely with the nematode tissues and processes initially perturbed following depletion of Wolbachia, embryogenesis and long-term sterilization, which are sustained for several months until the premature death of the adult worms. Our observations provide a cellular mechanism to account for the sustained reductions in microfilarial loads and interruption of transmission that occurs prior to macrofilaricidal activity following antibiotic therapy of filarial nematodes

Glucose modifies the effect of endovascular thrombectomy in patients with acute stroke: a pooled-data meta-analysis

Background and Purpose: Hyperglycemia is a negative prognostic factor following acute ischemic stroke but is not known whether glucose is associated with the effects of endovascular thrombectomy in patients with large vessel stroke. In a pooled-data meta-analysis, we analyzed whether serum glucose is a treatment modifier of the efficacy of endovascular thrombectomy in acute stroke. Methods: Seven randomized trials compared endovascular thrombectomy with standard care between 2010 and 2017 (HERMES Collaboration). 1764 patients with large vessel stroke were allocated to endovascular thrombectomy (n=871) or standard care (n=893). Measurements included blood glucose on admission and functional outcome [modified Rankin Scale (mRS) range: 0-6; lower scores indicating less disability] at 3 months. The primary analysis evaluated whether glucose modified the effect of EVT over standard care on functional outcome, using ordinal logistic regression to test the interaction between treatment and glucose level. Results: Median (IQR) serum glucose on admission was 120 (104-140) mg/dl [6.6mmol/l (5.7-7.7) mmol/l]. Endovascular thrombectomy (EVT) was better than standard care in the overall pooled-data analysis [common odds ratio (acOR), 2.00 (95% CI 1.69–2.38); however, lower glucose levels were associated with greater effects of EVT over standard care. The interaction was nonlinear such that significant interactions were found in subgroups of patients split at glucose < or > 90mg/dl (5.0mmol/l) [(p=0.019 for interaction, acOR 3.81 (95% CI 1.73–8.41) for patients < 90 mg/dl vs 1.83 (95% CI 1.53–2.19) for patients > 90 mg/dl], and glucose < or > 100mg/dl (5.5mmol/l) [(p=0.004 for interaction, acOR 3.17 (95% CI 2.04–4.93) vs acOR 1.72 (95% CI 1.42–2.08)], but not between subgroups above these levels of glucose. Conclusions: Endovascular thrombectomy improved stroke outcomes compared to standard treatment regardless of glucose levels but the treatment effects were larger at lower glucose levels, with significant interaction effects persisting up to 90 to 100mg/dl (5.0-5.5mmol/l). Whether tight control of glucose improves the efficacy of endovascular thrombectomy following large vessel stroke warrants appropriate testing

How does exposure to pesticides vary in space and time for residents living near to treated orchards?

This study investigated changes over 25 years (1987-2012) in pesticide usage in orchards in England and Wales and associated changes to exposure and risk for resident pregnant women living 100 and 1000 m downwind of treated areas. A model was developed to estimate aggregated daily exposure to pesticides via inhaled vapour and indirect dermal contact with contaminated ground, whilst risk was expressed as a hazard quotient (HQ) for reproductive and/or developmental endpoints. Results show the largest changes occurred between 1987 and 1996 with total pesticide usage reduced by ca. 25%, exposure per unit of pesticide applied slightly increased, and a reduction in risk per unit exposure by factors of 1.4 to 5. Thereafter, there were no consistent changes in use between 1996 and 2012, with an increase in number of applications to each crop balanced by a decrease in average application rate. Exposure per unit of pesticide applied decreased consistently over this period such that values in 2012 for this metric were 48-65% of those in 1987, and there were further smaller decreases in risk per unit exposure. All aggregated hazard quotients were two to three orders of magnitude smaller than one, despite the inherent simplifications of assuming co-occurrence of exposure to all pesticides and additivity of effects. Hazard quotients at 1000 m were 5 to 30 times smaller than those at 100 m. There were clear signals of the impact of regulatory intervention in improving the fate and hazard profiles of pesticides over the period investigated

Whole genome sequencing to investigate the emergence of clonal complex 23 Neisseria meningitidis serogroup Y disease in the United States

In the United States, serogroup Y, ST-23 clonal complex Neisseria meningitidis was responsible for an increase in meningococcal disease incidence during the 1990s. This increase was accompanied by antigenic shift of three outer membrane proteins, with a decrease in the population that predominated in the early 1990s as a different population emerged later in that decade. To understand factors that may have been responsible for the emergence of serogroup Y disease, we used whole genome pyrosequencing to investigate genetic differences between isolates from early and late N. meningitidis populations, obtained from meningococcal disease cases in Maryland in the 1990s. The genomes of isolates from the early and late populations were highly similar, with 1231 of 1776 shared genes exhibiting 100% amino acid identity and an average πN = 0.0033 and average πS = 0.0216. However, differences were found in predicted proteins that affect pilin structure and antigen profile and in predicted proteins involved in iron acquisition and uptake. The observed changes are consistent with acquisition of new alleles through horizontal gene transfer. Changes in antigen profile due to the genetic differences found in this study likely allowed the late population to emerge due to escape from population immunity. These findings may predict which antigenic factors are important in the cyclic epidemiology of meningococcal disease