Field Guide to a Hybrid Landscape

In Field Guide to a Hybrid Landscape Dana Fritz traces the evolution of the Bessey Ranger District and Nursery of the Nebraska National Forest and Grasslands. Fritz’s contemporary photographs of this unique ecosystem, with provocative environmental essays, maps, and historical photographs from the U.S. Forest Service archives, illuminate the complex environmental and natural history of the site, especially as it relates to built environments, land use, and climate change. The Nebraska National Forest at Halsey, as it is known colloquially, is the largest hand-planted forest in the Western Hemisphere, and formerly in the world. This hybrid landscape of a conifer forest overlaid onto a semiarid grassland just west of the one-hundredth meridian was an ambitious late nineteenth-century idea to create a timber industry, to reclaim a landscape considered disordered and unproductive, and to change the local climate in northcentral Nebraska. While the planners seemed not to appreciate the native grasslands that form the ecosystem of the Nebraska Sandhills, they did recognize the reliable water from the Dismal and Middle Loup Rivers that border the site. In 1902 the first federal nursery was established as part of the Dismal River Forest Reserve to produce seedlings for plains homesteads and the adjacent treeless tract of land. At that time tree planting was not used for carbon sequestration but to mitigate the wind and evaporation of moisture. The Bessey Nursery now produces replacement seedlings for burned and beetle-damaged forests in the Rocky Mountains and for the Nebraska Conservation Trees Program. This constructed landscape of row-crop trees that were protected from fire for decades, yet never commercially harvested for timber, provides a rich metaphor for current environmental predicaments. The late nineteenth-century effort to reclaim with trees what was called the Great American Desert has evolved to a focus on twenty-first-century conservation, grassland restoration, and reforestation, all of which work to sequester carbon, maintain natural ecosystem balance, and mitigate large-scale climate change. Field Guide to a Hybrid Landscape offers a visual and critical examination of this unique managed landscape, which has implications far beyond its borders. 144 pages 78 photographs, 2 illustrations, 9 maps This book is available from University of Nebraska Press: https://www.nebraskapress.unl.edu/bison-books/9781496227775

Cytotoxicity of the Ascidian Cystodytes dellechiajei Against Tumor Cells and Study of the Involvement of Associated Microbiota in the Production of Cytotoxic Compounds

Many cytotoxic compounds of therapeutic interest have been isolated from marine invertebrates, and some of them have been reported to be of microbial origin. Pyridoacridine alkaloids are the main compounds extracted from the ascidian Cystodytes dellechiajei. Here we describe the in vitro antiproliferative activity against different tumor cell lines of the ascidian extracts and provide some insights on the role of the microbial community associated with the tunicate in the production of these compounds. C. dellechiajei extracts showed remarkably high antiproliferative activity (IC50 ≤5 μg/mL) in human lung carcinoma A-549, colon adenocarcinoma H-116, pancreatic adenocarcinoma PSN-1 and breast carcinoma SKBR3 cell lines. Moreover, we found that the maximum activity was located in the tunic tissue of the colony, which harbours a microbial community. In order to ascertain the involvement of this community in the synthesis of the bioactive compounds different approachs that included culture and culture independent methods were carried out. We undertook a screening for antiproliferative activities of the bacterial isolates from the ascidian, as well as a comprative analysis of the cytotoxic activities and the microbial communities from two color morphs of the ascidian, green and blue. In addition, the changes of the antiproliferative activities and the composition of the microbial communities were studied from ascidians kept in aquaria and treated with antibiotics for one month. Our data obtained from the different experiments did not point out to bacteria as the source of the cytotoxic compounds, suggesting thus an ascidian origin

Electrochemical Doping as a Way to Enhance Water Photooxidation on Nanostructured Nickel Titanate and Anatase Electrodes

A number of metal oxides have been proposed as useful materials for the photoelectrochemical (PEC) production of hydrogen from water. However, up to now, an ideal standalone material has not been found. We have investigated the possible use of nickel titanate (NiTiO3) nanorods as a photoanode. Although these electrodes absorb visible light, they show a modest PEC behavior. Interestingly, the photocurrent for water oxidation undergoes a 30-fold enhancement after an optimized reductive electrochemical pretreatment. Here, the induced doping is studied and compared with the corresponding for anatase nanoporous electrodes. The results reveal the key role of the electrolyte pH as well as the size of the electrode building blocks. The photocurrent promotion upon the electrochemical pretreatment can be ascribed to an enhanced charge transport linked to the ability of proton insertion in the crystal structure.We are grateful to the Spanish Ministry of Economy and Competitiveness (MINECO) for financial support through projects PRI-PIBIN-2011-0816, MAT2012-37676 and MAT2015-71727-R (co-financed with FEDER funds by the European Union). S.A. also thanks DST, New Delhi, for the sanction of an India–Spain collaborative research grant (DST/INT/Spain/P-37/11 dt.16th Dec 2011). D.M.-S. acknowledges MINECO for financial support through project MAT2014-59961-C2-2-R, and the Spanish Ministry of Education and Science for the award of an FPI Fellowship (BES-2004-5194)

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe