Helium bubble formation in ultrafine and nanocrystalline tungsten under different extreme conditions

We have investigated the effects of helium ion irradiation energy and sample temperature on the performance of grain boundaries as helium sinks in ultrafine grained and nanocrystalline tungsten. Irradiations were performed at displacement and non-displacement energies and at temperatures above and below that required for vacancy migration. Microstructural investigations were performed using Transmission Electron Microscopy (TEM) combined with either in-situ or ex-situ ion irradiation. Under helium irradiation at an energy which does not cause atomic displacements in tungsten (70 eV), regardless of temperature and thus vacancy migration conditions, bubbles were uniformly distributed with no preferential bubble formation on grain boundaries. At energies that can cause displacements, bubbles were observed to be preferentially formed on the grain boundaries only at high temperatures where vacancy migration occurs. Under these conditions, the decoration of grain boundaries with large facetted bubbles occurred on nanocrystalline grains with dimensions less than 60 nm. We discuss the importance of vacancy supply and the formation and migration of radiation-induced defects on the performance of grain boundaries as helium sinks and the resulting irradiation tolerance of ultrafine grained and nanocrystalline tungsten to bubble formatio

A threat to climate-secure European futures? Exploring racial logics and climate-induced migration in US and EU climate security discourses

Whether formulated as a security risk, a form of climate adaptation, a legal dilemma, or an issue of (in)justice, the debate on climate change and migration draws upon multiple, oftentimes contradictory, discourses. This paper examines the role of racial identities in debates about the security implications of climate-induced migration (CIM). The paper proposes a reconceptualization of ‘racial logics’: a form of discursive construction that connects naturalized assumptions about racialized Others with possible outcomes in conditions of future climate insecurity. The paper argues that 'Muslim' and 'African' migrant populations – in the context of possible CIM from the Middle East and North Africa (MENA) region to the EU – are racialized with a potential capacity for radicalization and terrorism. Constructed as racialized Others, 'Muslim' and 'African' migrant populations could face exclusionary containment policies in climate-insecure futures. The article concludes with a call to challenge racial logics and the restrictive, unjust possibilities they suggest for future climate security politics

Distinct requirements for the Rad32(Mre¹¹) nuclease and Ctp1(CtIP) in the removal of covalently bound topoisomerase I and II from DNA

For a cancer cell to resist treatment with drugs that trap topoisomerases covalently on the DNA, the topoisomerase must be removed. In this study, we provide evidence that the Schizosaccharomyces pombe Rad32Mre11 nuclease activity is involved in the removal of both Top2 from 5′ DNA ends as well as Top1 from 3′ ends in vivo. A ctp1CtIP deletion is defective for Top2 removal but overproficient for Top1 removal, suggesting that Ctp1CtIP plays distinct roles in removing topoisomerases from 5′ and 3′ DNA ends. Analysis of separation of function mutants suggests that MRN-dependent topoisomerase removal contributes significantly to resistance against topoisomerase-trapping drugs. This study has important implications for our understanding of the role of the MRN complex and CtIP in resistance of cells to a clinically important group of anticancer drugs

Perspectives on Novel Refractory Amorphous High-Entropy Alloys in Extreme Environments

Two new refractory amorphous high-entropy alloys (RAHEAs) within the W--Ta--Cr--V and W--Ta--Cr--V--Hf systems were herein synthesized using magnetron-sputtering and tested under high-temperature annealing and displacing irradiation using \textit{in situ} Transmission Electron Microscopy. While the WTaCrV RAHEA was found to be unstable under such tests, additions of Hf in this system composing a new quinary WTaCrVHf RAHEA was found to be a route to achieve stability both under annealing and irradiation. A new effect of nanoprecipitate reassembling observed to take place within the WTaCrVHf RAHEA under irradiation indicates that a duplex microstructure composed of an amorphous matrix with crystalline nanometer-sized precipitates enhances the radiation response of the system. It is demonstrated that tunable chemical complexity arises as a new alloy design strategy to foster the use of novel RAHEAs within extreme environments. New perspectives for the alloy design and application of chemically-complex amorphous metallic alloys in extreme environments are presented with focus on their thermodynamic phase stability when subjected to high-temperature annealing and displacing irradiation

Recombination in the Open-Ended Value Landscape of Digital Innovation

Digital innovation introduces a new open-ended value landscape to anyone seeking to generate or capture new value. To understand this landscape, we distinguish between design recombination and use recombination, explore how they play out together, and redirect the attention from products and services toward digital resources. Digital resources serve as building-blocks in digital innovation, and they hold the potential to simultaneously be part of multiple value paths, offered through design recombination and assembled through use recombination. Building on this perspective, we offer the value spaces framework as a tool for better understanding value creation and capture in digital innovation. We illustrate the framework and offer the early contours of a research agenda for information systems researchers

NASA 26 GHz Polar Subnet in 2020+

The next generation Earth observing satellites will face challenges in supporting high rate space communications from the increasingly sophisticated instruments. Emerging applications will need space-to-ground links with data rates forecasted to be in the 1-20 Gbps range. To meet these challenges, NASA is designing and integrating a 26 GHz Polar Subnet to support space communication needs in 2020 and beyond. This paper describes the current effort of the Space Communications and Navigation Program's Near Earth Network (NEN), managed out of Goddard Space Flight Facility (GSFC), to deploy a 26 GHz Polar Subnet including the implementation, topology, capabilities, architecture design, operations and key design trades

Predictors and outcomes of patient safety culture in hospitals

<p>Abstract</p> <p>Background</p> <p>Developing a patient safety culture was one of the recommendations made by the Institute of Medicine to assist hospitals in improving patient safety. In recent years, a multitude of evidence, mostly originating from developed countries, has been published on patient safety culture. One of the first efforts to assess the culture of safety in the Eastern Mediterranean Region was by El-Jardali et al. (2010) in Lebanon. The study entitled "The Current State of Patient Safety Culture: a study at baseline" assessed the culture of safety in Lebanese hospitals. Based on study findings, the objective of this paper is to explore the association between patient safety culture predictors and outcomes, taking into consideration respondent and hospital characteristics. In addition, it will examine the correlation between patient safety culture composites.</p> <p>Methods</p> <p>Sixty-eight hospitals and 6,807 respondents participated in the study. The study which adopted a cross sectional research design utilized an Arabic-translated version of the Hospital Survey on Patient Safety Culture (HSOPSC). The HSOPSC measures 12 patient safety composites. Two of the composites, in addition to a patient safety grade and the number of events reported, represented the four outcome variables. Bivariate and mixed model regression analyses were used to examine the association between the patient safety culture predictors and outcomes.</p> <p>Results</p> <p>Significant correlations were observed among all patient safety culture composites but with differences in the strength of the correlation. Generalized Estimating Equations for the patient safety composite scores and respondent and hospital characteristics against the patient safety grade and the number of events reported revealed significant correlations. Significant correlations were also observed by linear mixed models of the same variables against the frequency of events reported and the overall perception of safety.</p> <p>Conclusion</p> <p>Event reporting, communication, patient safety leadership and management, staffing, and accreditation were identified as major patient safety culture predictors. Investing in practices that tackle these issues and prioritizing patient safety is essential in Lebanese hospitals in order to improve patient safety. In addition, further research is needed to understand the association between patient safety culture and clinical outcomes.</p

The only African wild tobacco, Nicotiana africana: Alkaloid content and the effect of herbivory

Herbivory in some Nicotiana species is known to induce alkaloid production. This study examined herbivore-induced defenses in the nornicotine-rich African tobacco N. africana, the only Nicotiana species indigenous to Africa. We tested the predictions that: 1) N. africana will have high constitutive levels of leaf, flower and nectar alkaloids; 2) leaf herbivory by the African bollworm Helicoverpa armigera will induce increased alkaloid levels in leaves, flowers and nectar; and 3) increased alkaloid concentrations in herbivore-damaged plants will negatively affect larval growth. We grew N. africana in large pots in a greenhouse and exposed flowering plants to densities of one, three and six fourth-instar larvae of H. armigera, for four days. Leaves, flowers and nectar were analyzed for nicotine, nornicotine and anabasine. The principal leaf alkaloid was nornicotine (mean: 28 µg/g dry mass) followed by anabasine (4.9 µg/g) and nicotine (0.6 µg/g). Nornicotine was found in low quantities in the flowers, but no nicotine or anabasine were recorded. The nectar contained none of the alkaloids measured. Larval growth was reduced when leaves of flowering plants were exposed to six larvae. As predicted by the optimal defense theory, herbivory had a localized effect and caused an increase in nornicotine concentrations in both undamaged top leaves of herbivore damaged plants and herbivore damaged leaves exposed to one and three larvae. The nicotine concentration increased in damaged compared to undamaged middle leaves. The nornicotine concentration was lower in damaged leaves of plants exposed to six compared to three larvae, suggesting that N. africana rather invests in new growth as opposed to protecting older leaves under severe attack. The results indicate that the nornicotine-rich N. africana will be unattractive to herbivores and more so when damaged, but that potential pollinators will be unaffected because the nectar remains alkaloid-free even after herbivory