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Scanning tunneling microscopy and spectroscopy (STM/STS) are used to electronically switch atomically-thin memristors, referred to as “atomristors”, based on a graphene/molybdenum disulfide (MoS2)/Au heterostructure. A gold-assisted exfoliation method was used to produce near-millimeter (mm) scale MoS2 on Au thin-film substrates, followed by transfer of a separately exfoliated graphene top layer. Our results reveal that it is possible to switch the conductivity of a graphene/MoS2/Au memristor stack using an STM tip. These results provide a path to further studies of atomically-thin memristors fabricated from heterostructures of two-dimensional materials such as graphene and transition metal dichalcogenides (TMDs).
Reward processing deficits have been implicated in the etiology of depression. A blunted reward positivity (RewP), an event-related potential elicited by feedback to monetary gain relative to loss, predicts new onsets and increases in depression symptoms. Etiological models of depression also highlight stressful life events. However, no studies have examined whether stressful life events moderate the effect of the RewP on subsequent depression symptoms. We examined this question during the key developmental transition from childhood to adolescence.
A community sample of 369 children (mean age of 9) completed a self-report measure of depression symptoms. The RewP to winning v. losing was elicited using a monetary reward task. Three years later, we assessed stressful life events occurring in the year prior to the follow-up. Youth depressive symptoms were rated by the children and their parents at baseline and follow-up.
Stressful life events moderated the effect of the RewP on depression symptoms at follow-up such that a blunted RewP predicted higher depression symptoms in individuals with higher levels of stressful life events. This effect was also evident when events that were independent of the youth's behavior were examined separately.
These results suggest that the RewP reflects a vulnerability for depression that is activated by stress.
Background: Stroke is a rare neurological disease in children, with an annual incidence of 2 - 13/100,000 children per year. Pediatric stroke is associated with significant morbidity and mortality lasting many decades. Diagnosis of pediatric stroke is challenging and often delayed, limiting options for acute intervention, and the pharmacological and mechanical recanalization strategies that have revolutionized adult stroke remain undefined in children. Clinicians are left to draw conclusions from other retrospective cohort studies or case reports and extrapolate adult guidelines to the pediatric population. The TIPS trial eligibility criteria are often used in clinical practice, despite not being validated for this purpose. We present here the case of a healthy 14 year old male who was treated with intravenous tissue plasminogen activator (IV tPA) for a presumed arterial ischemic stroke without large vessel occlusion on neuroimaging. Methods: Retrospective chart review Results: Not applicable Conclusions: Following the administration of IV tPA, the patient made a full recovery. While we do not recommend the routine use of IV tPA for treatment of presumed large vessel or small vessel in children, we suggest that the decision to proceed with IV tPA be considered on a case-by-case basis.
The need to innovate is relevant to many firms around the globe and is particularly pressing for those in emerging markets. They face global competition, are under-resourced, and suffer from weaker institutional support. It is suggested that to innovate successfully in this context, indigenous firms would benefit from focusing on managing their current knowledge base more efficiently. We know little about how knowledge management works outside developed economies and which knowledge governance mechanisms have more influence than others in the context of emerging economies. To address this gap, we explore how context may matter for the use of knowledge governance mechanisms and their effect on innovation performance in Brazilian firms. Using the survey data of 109 firms, structural equation modelling, and cluster analysis, our findings suggest that the joint application of knowledge-focused rewards, organizational design, and information and communication technologies that support knowledge processes is critical for boosting innovation performance. We discuss how the peculiarities of the Brazilian context may shape these findings. Our article contributes to the knowledge management and innovation literature by demonstrating that the joint effects of bundles of knowledge governance mechanisms and contextual variables should be explored in order to understand their impact on organizational outcomes.
The glycaemic index (GI) and glycaemic load (GL) are involved in the aetiology of different diseases, and they could be related to the development of colorectal cancer (CRC). The aim of this study was to evaluate the association between the quality and quantity indicators of carbohydrates consumed by the population of Córdoba (Argentina) and the odds of developing CRC in 2008–2016 period. A case–control study was conducted with 492 participants (161/331 cases/controls), interviewed through a validated FFQ. Multilevel logistic regression models were used to assess the effect of GI, GL and the quantity or weekly intake of high-GI foods on CRC occurrence, following adjustment for individual/first-level covariates, and using level of urbanisation as the contextual variable. The models were stratified by sex. Participants in the highest v. lowest tertile of dietary GL and weekly intake of high-GI foods had increased odds of CRC presence in the entire sample (OR 1·64, 95 % CI 1·16, 2·34 and OR 1·11, 95 % CI 1·09, 1·14, respectively) and in women (OR 1·98, 95 % CI 1·24, 3·18 and OR 1·41, 95 % CI 1·09, 1·83, respectively). In men, the second tertile of GL and weekly intake of high-GI foods were associated with CRC (OR 1·44, 95 % CI 1·04, 1·99 and OR 1·48, 95 % CI 1·32, 1·65, respectively). Also, GI was associated with CRC in women (highest v. lowest tertile OR 2·12, 95 % CI 1·38, 3·27). In addition to the quantity and quality of carbohydrates intake, it is important to consider the frequency of consumption of high-GI foods in CRC prevention.
Lake Untersee is a perennially ice-covered Antarctic lake that consists of two basins. The deepest basin, next to the Anuchin Glacier is aerobic to its maximum depth of 160 m. The shallower basin has a maximum depth of 100 m, is anoxic below 80 m, and is shielded from convective currents. The thermal profile in the anoxic basin is unusual in that the water temperature below 50 m is constant at 4°C but rises to 5°C between 70 m and 80 m depth, then drops to 3.7°C at the bottom. Field measurements were used to conduct a thermal and stability analysis of the anoxic basin. The shape of the thermal maximum implies two discrete locations of energy input, one of 0.11 W m-2 at 71 m depth and one of 0.06 W m-2 at 80 m depth. Heat from microbial activity cannot account for the required amount of energy at either depth. Instead, absorption of solar radiation due to an increase in water opacity at these depths can account for the required energy input. Hence, while microbial metabolism is not an important source of heat, biomass increases opacity in the water column resulting in greater absorption of sunlight.
Catalytic processes are critical steps in numerous industrial processes. The discovery of high reactivity of defects in metal-free two-dimensional materials has bolstered their emergence as catalysts. Here we consider the effect of defect-inducing methods in hexagonal boron nitride (h-BN) on their performance for olefin and CO2 hydrogenation. We compare the changes introduced by ball milling and heat treatment in h-BN and show how varying the treatment conditions can impact the properties. We provide some evidence of the reactivity of the powders. Our results highlight how characterization can be exploited to assess the potential catalytic activity of h-BN for heterogeneous catalysis.
Two metal fillers with TiC nanoparticles (TiC NPs) of less than 100 nm for the overlay process is an alternative to hardfacing for treating surfaces subjected to severe wear. In this work, the effect of tribological behavior for TiC NPs addition on two Co-based filler materials, as well as the dilutions, was studied. Mixtures of Co-based filler metals without and with 0.5% and 2% TiC NPs were deposited onto D2 steel plates using PTA (Plasma Transferred Arc). The BET surface area was 0.17 m2 g-1 and 0.31 m2 g-1, respectively, for Stellite 6 and 12. The distribution of ca 23% macroporous for Stellite 6 was sufficient to get inside the TiC NPs, as well as in the case of Stellite 12, with a pore distribution of ca 13%. Stellite 12 has an increase in the dilutions (70%) and enthalpies showed endothermic reactions. Stellite 6 with NPs was determined to be most effective in increasing the wear resistance.
Laser welding processes offer significant advantages such as high welding speed, narrow heat affected zone and quality of the welding joint. In this study, the process parameters of laser power and welding speed were modified for AISI 1018 steel plates of 8 mm thickness and compared using finite element method. The results of cross-section microstructure, heat affected zone and fusion zone were characterized. The grain refinement was affected as the parameters were modified. Tensile and microhardness tests were performed to determine the mechanical properties of the welding joints. Microhardness increased in fusion zone and decreased in heat affected zone. Tensile test showed ductile fracture in heat affected zone of the welding joints. The simulated profiles were compared with the experimental observations showing a reasonable agreement.
We classify and analyze the orbits of the Kepler problem on surfaces of constant curvature (both positive and negative,
, respectively) as functions of the angular momentum and the energy. Hill's regions are characterized, and the problem of time-collision is studied. We also regularize the problem in Cartesian and intrinsic coordinates, depending on the constant angular momentum, and we describe the orbits of the regularized vector field. The phase portraits both for
are pointed out.
This article suggests that the business history of emerging markets should be seen as an alternative business history, rather than merely adding new settings to explore established core debates. The discipline of business history evolved around the corporate strategies and structures of developed economies. The growing literature on the business history of emerging markets addresses contexts that are different from those of developed markets. These regions had long eras of foreign domination, had extensive state intervention, faced institutional inefficiencies, and experienced extended turbulence. This article suggests that this context drove different business responses than are found in the developed world. Entrepreneurs counted more than managerial hierarchies; immigrants and diaspora were critical sources of entrepreneurship; illegal and informal forms of business were common; diversified business groups rather than the M-form became the major form of large-scale business; corporate strategies to deal with turbulence were essential; and radical corporate social-responsibility concepts were pursued by some firms.