137 research outputs found

    Be a Fulbright Scholar—Lessons and Experiences of AIS Fulbright Scholars

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    To achieve a truly global perspective in information systems (IS) that enhances education and research, IS academics can do more than study and teach global IS topics. We encourage IS academics to engage in an international immersion experience themselves. The article describes experiences of Fulbright Scholars, and argues for the need of more global education for IS academics. These views were presented during a panel session at the Americas Conference on Information Systems (AMCIS) 2012. The panelists touched on logistical issues such as grant application, living conditions, working with a host institution’s faculty and students, and receiving support from their home university. Participants shared their experiences in India, Poland, Portugal, the Azores, Mongolia, and Nepal. The article concludes with lessons learned

    The angiotensin II type I receptor contributes to impaired cerebral blood flow autoregulation caused by placental ischemia in pregnant rats

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    BACKGROUND: Placental ischemia and hypertension, characteristic features of preeclampsia, are associated with impaired cerebral blood flow (CBF) autoregulation and cerebral edema. However, the factors that contribute to these cerebral abnormalities are not clear. Several lines of evidence suggest that angiotensin II can impact cerebrovascular function; however, the role of the renin angiotensin system in cerebrovascular function during placental ischemia has not been examined. We tested whether the angiotensin type 1 (AT1) receptor contributes to impaired CBF autoregulation in pregnant rats with placental ischemia caused by surgically reducing uterine perfusion pressure. METHODS: Placental ischemic or sham operated rats were treated with vehicle or losartan from gestational day (GD) 14 to 19 in the drinking water. On GD 19, we assessed CBF autoregulation in anesthetized rats using laser Doppler flowmetry. RESULTS: Placental ischemic rats had impaired CBF autoregulation that was attenuated by treatment with losartan. In addition, we examined whether an agonistic autoantibody to the AT1 receptor (AT1-AA), reported to be present in preeclamptic women, contributes to impaired CBF autoregulation. Purified rat AT1-AA or vehicle was infused into pregnant rats from GD 12 to 19 via mini-osmotic pumps after which CBF autoregulation was assessed. AT1-AA infusion impaired CBF autoregulation but did not affect brain water content. CONCLUSIONS: These results suggest that the impaired CBF autoregulation associated with placental ischemia is due, at least in part, to activation of the AT1 receptor and that the RAS may interact with other placental factors to promote cerebrovascular changes common to preeclampsia

    Optimal military spending in the US: A time series analysis

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    This paper extends previous work on the optimal size of government spending by including nested functional decompositions of military spending into consumption and investment. Post World War II US data are then used to estimate nested non-linear growth models using semi-parametric methods. As expected, investments in military and non-military expenditure are both found to be productive expenditures with respect to the private production. Moreover there is little evidence to suggest that current military spending is having a negative impact on economic growth in the US, while civilian consumption only tends to have only a weak impact. This does not imply that society will necessarily benefit from a reallocation of more spending to the military sector, nor that it is the best way to achieve economic growth. © 2010 Elsevier B.V

    Challenges in Complex Systems Science

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    FuturICT foundations are social science, complex systems science, and ICT. The main concerns and challenges in the science of complex systems in the context of FuturICT are laid out in this paper with special emphasis on the Complex Systems route to Social Sciences. This include complex systems having: many heterogeneous interacting parts; multiple scales; complicated transition laws; unexpected or unpredicted emergence; sensitive dependence on initial conditions; path-dependent dynamics; networked hierarchical connectivities; interaction of autonomous agents; self-organisation; non-equilibrium dynamics; combinatorial explosion; adaptivity to changing environments; co-evolving subsystems; ill-defined boundaries; and multilevel dynamics. In this context, science is seen as the process of abstracting the dynamics of systems from data. This presents many challenges including: data gathering by large-scale experiment, participatory sensing and social computation, managing huge distributed dynamic and heterogeneous databases; moving from data to dynamical models, going beyond correlations to cause-effect relationships, understanding the relationship between simple and comprehensive models with appropriate choices of variables, ensemble modeling and data assimilation, modeling systems of systems of systems with many levels between micro and macro; and formulating new approaches to prediction, forecasting, and risk, especially in systems that can reflect on and change their behaviour in response to predictions, and systems whose apparently predictable behaviour is disrupted by apparently unpredictable rare or extreme events. These challenges are part of the FuturICT agenda

    A review of spatial causal inference methods for environmental and epidemiological applications

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    The scientific rigor and computational methods of causal inference have had great impacts on many disciplines, but have only recently begun to take hold in spatial applications. Spatial casual inference poses analytic challenges due to complex correlation structures and interference between the treatment at one location and the outcomes at others. In this paper, we review the current literature on spatial causal inference and identify areas of future work. We first discuss methods that exploit spatial structure to account for unmeasured confounding variables. We then discuss causal analysis in the presence of spatial interference including several common assumptions used to reduce the complexity of the interference patterns under consideration. These methods are extended to the spatiotemporal case where we compare and contrast the potential outcomes framework with Granger causality, and to geostatistical analyses involving spatial random fields of treatments and responses. The methods are introduced in the context of observational environmental and epidemiological studies, and are compared using both a simulation study and analysis of the effect of ambient air pollution on COVID-19 mortality rate. Code to implement many of the methods using the popular Bayesian software OpenBUGS is provided

    Highly-parallelized simulation of a pixelated LArTPC on a GPU

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    The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

    Mesures des champs magnétiques faibles dans un environnement industriel

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    Il s'agit de connaître les caractéristiques magnétiques des équipements électroniques destinés aux satellites ou aux sondes scientifiques. Après avoir compensé le champ terrestre, il faut mesurer les inductions résiduelles de ces matériels en présence de bruits dont l'amplitude excède la valeur du signal à mesurer. L'échantillon est placé sur un plateau en rotation. Le magnétomètre détecte une induction tournante. On établit la corrélation de ce signal avec la rotation du plateau dans un détecteur synchrone, ce qui permet d'extraire le signal du bruit. L'exposé comporte : — L'examen des bruits magnétiques dans l'environnement industriel. — La description du système de mesure et l'analyse de ses performances

    Nitric oxide in the developing kidney.

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    Although nitric oxide (NO) has a well-established role in regulating renal function in the adult, recent studies point to perhaps an even more critical role for NO in maintaining basal renal blood flow (RBF) and glomerular filtration rate (GFR) in the developing kidney. The immature kidney has enhanced renal hemodynamic and functional responses to stimulation and inhibition of NO synthesis when compared with the adult, and these increased responses are not mediated by prostaglandins. Increased intrarenal activity of NO in the developing kidney counter-regulates the highly activated renin angiotensin system by modulating the angiotensin II-mediated vasoconstriction of the developing renal vasculature, the angiotensin II effects on GFR, as well as renin release. Localization studies demonstrate that NO acts on neonatal RBF and stabilization of GFR through an intrarenal distribution of the synthesizing enzyme, nitric oxide synthase, that is different from that of the adult. The developing kidney is dependent on NO to maintain RBF and GFR during periods of hypoxemia, protecting against renal injury, such as acute renal failure. In summary, NO is vital in the developing kidney to maintain normal physiological function and to protect the immature kidney during pathophysiological stress
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