5,526 research outputs found

    Surface-acoustic-wave driven planar light-emitting device

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    Electroluminescence emission controlled by means of surface acoustic waves (SAWs) in planar light-emitting diodes (pLEDs) is demonstrated. Interdigital transducers for SAW generation were integrated onto pLEDs fabricated following the scheme which we have recently developed. Current-voltage, light-voltage and photoluminescence characteristics are presented at cryogenic temperatures. We argue that this scheme represents a valuable building block for advanced optoelectronic architectures

    Two new intermediate polars with a soft X-ray component

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    Aims. We analyze the first X-ray observations with XMM-Newton of 1RXS J070407.9+262501 and 1RXS 180340.0+401214, in order to characterize their broad-band temporal and spectral properties, also in the UV/optical domain, and to confirm them as intermediate polars. Methods. For both objects, we performed a timing analysis of the X-ray and UV/optical light curves to detect the white dwarf spin pulsations and study their energy dependence. For 1RXS 180340.0+401214 we also analyzed optical spectroscopic data to determine the orbital period. X-ray spectra were analyzed in the 0.2–10.0 keV range to characterize the emission properties of both sources. Results. We find that the X-ray light curves of both systems are energy dependent and are dominated, below 3–5 keV, by strong pulsations at the white dwarf rotational periods (480 s for 1RXS J070407.9+262501 and 1520.5 s for 1RXS 180340.0+401214). In 1RXS 180340.0+401214 we also detect an X-ray beat variability at 1697 s which, together with our new optical spectroscopy, favours an orbital period of 4.4 h that is longer than previously estimated. Both systems show complex spectra with a hard (temperature up to 40 keV) optically thin and a soft (kT ∼ 85–100 eV) optically thick components heavily absorbed by material partially covering the X-ray sources. Conclusions. Our observations confirm the two systems as intermediate polars and also add them as new members of the growing group of “soft” systems which show the presence of a soft X-ray blackbody component. Differences in the temperatures of the blackbodies are qualitatively explained in terms of reprocessing over different sizes of the white dwarf spot. We suggest that systems showing cooler soft X-ray blackbody components also possess white dwarfs irradiated by cyclotron radiation

    Three resilient megastructures by Pier Luigi Nervi

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    Resilience, as the ability of a structure to withstand threats and continue to function, it is normally related to durability and performance to accepted standards over time. The resilience of a structure can be threatened by poor design, changes in the public's perception of style, the potential for a change-in-use and structural attack; catastrophic events such as fire, explosion or impact are usually considered the main threats for Resilience. In the contemporary built environment Resilience is considered increasingly important; it has, in fact, become one of the major design issues, especially for large, iconic or public and prominent structures: this has not always been the case. Following the Second World War, building designers faced the necessity to conceive projects within severe financial constraints, hence the proliferation of a low quality and limited life-span structures; buildings which were designed to be replaceable, cheap and perhaps anonymous. This was thought to be an effec-tive answer to quickly accommodate the large number of people moving towards the urban environment partly destroyed by the WWII. These very buildings now constitute the backbone of our urban scenery and although some still function adequately, many are perfect examples of structures which exhibit a lack of re-silience. Fortunately, there were a few designers who refused this post-war tendency and attempted to design lasting structures of quality: most of them were engineers. This is not a coincidence, engineers had less to do with the issue of providing residential accommodations and more with the erection of large structures which necessitated a higher quality control on materials and technologies: Pier Luigi Nervi was one of them. This work considers three large structures designed and built fifty years ago,in 1961, by the Italian engineer. The structures are the Bus Station at the George Washington Bridge in New York (USA); The Burgo Paper Mill in Mantua (Italy); and the Palace of Labour in Turin (Italy). All of these buildings are hybrid structures (concrete and steel), an unusual choice for Nervi that perhaps reects the design climate at the time; These buildings reacted quite differently to the events that have occurred over the past half century. One of the key factors to achieve resilience it is considered to be the quality of the buildings, which includes their ability to perform maintenance. The lack of which for whatever reason, this paper aims to demonstrate, will inevitably result in a weak performance in terms of resilience on the long run

    Special Issue: Advances in SARS-CoV-2 Infection

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    Since the beginning of the pandemic, and particularly during the first and second waves, the goal of this Special Issue has been to highlight the crucial aspects of SARS- CoV-2 and the disease in light of the new knowledge that was emerging. A total of 15 manuscripts have been published in this Special Issue. These papers provided insights into epidemiology, pathogenesis, epigenetics COVID-19 emergencies in hospital settings, advanced diagnosis, vaccination, and SARS-CoV-2 infection in the experimental setting. The high scientific rigor, originality, and, for some of them, the high number of citations obtained, are well evident

    The deleterious effect of arteriovenous flow reversal during experimental free muscle transfer.

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    Arteriovenous flow reversal (AVR) has been used experimentally to salvage ischemic limbs and to create novel skin flaps with some success. The clinical applicability of AVR in muscle by way of two arteriovenous anastomoses in the rabbit was investigated. Twenty-four rabbits were divided into two groups. In Group 1 (control), the rectus femoris muscle was harvested and transplanted in the opposite thigh, anastomosing the donor femoral artery to the recipient femoral artery, and the donor rectus femoris vein to the recipient femoral vein. In Group 2 (flow reversal), the same procedure was done except the donor artery was anastomosed to the recipient vein and vice versa. Six and 24 hr postoperatively, specimens were compared macroscopically and by weight and histology. Reversed flow muscles were significantly heavier than control muscles at 6 hr and at 24 hr. Histologically, 6 hr of AVR caused edema, intramuscular hemorrhage, neutrophil infiltration, and thrombosis of most vessels. By 24 hr muscle cell degeneration was well advanced. All control muscles were viable, with only mild edema and slight peripheral necrosis. Possible reasons for the failure of AVR in muscle are discussed. On the basis of these results, AVR in free muscle transfer is not advocated

    A regional-scale conceptual and numerical groundwater flow model in fluvio-glacial sediments for the Milan Metropolitan area (Northern Italy)

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    Study region: The Milan metropolitan area lies on one of the most important aquifer in Italy, heavily exploited for public and industrial water supply. The area, covering 3135 km2 in the Po Plain (Northern Italy) with a continental climate, is bounded by the Po, the Adda and the Ticino rivers and by the prealpine foothills. Regional hydrology is characterised by a network of natural and man-made elements, and lowland springs. The sedimentary sequence, from bottom to top, is formed by meandering river plain deposits, the distal fringe of the glacial outwash plains and proximal braid-plain deposits. Study focus: This study proposes a general approach for aquifer geometry reconstruction and hydrodynamic parametrization of hydrofacies in fluvio-glacial deposits, and their implementation into a 3D regional groundwater flow model. This approach is based on sedimentologically-defined lithofacies/hydrofacies and their correlation in space to obtain nearly homogeneous subunits starting from available data (i.e. 8628 borehole logs, grain size distributions, well tests) and sedimentological knowledge. New hydrological insights for the region: The calibrated 3D FEM groundwater model allows quantifying the main components of the hydrogeological budget at the regional scale, and the fluxes among the different hydro-stratigraphic units. A sensitivity analysis of groundwater levels to the main recharge components suggests importance of anthropogenic disturbances with respect to natural recharge, and that land-use change may impact water resources more than climate change

    Torre Alfina Deep Geothermal Reservoir

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    The Castel Giorgio-Torre Alfina (CG-TA, central Italy) is a geothermal reservoir whose fluids are hosted in a carbonate formation at temperatures ranging between 120°C and 210°C. Data from deep wells suggest the existence of convective flow. We present the 3D numerical model of the CG-TA to simulate the undisturbed natural geothermal field and investigate the impacts of the exploitation process. The open source finite-element code OpenGeoSys is applied to solve the coupled systems of partial differential equations. The commercial software FEFLOW® is also used as additional numerical constraint. Calculated pressure and temperature have been calibrated against data from geothermal wells. The flow field displays multicellular convective patterns that cover the entire geothermal reservoir. The resulting thermal plumes protrude vertically over 3 km at Darcy velocity of about  m/s. The analysis of the exploitation process demonstrated the sustainability of a geothermal doublet for the development of a 5 MW pilot plant. The buoyant circulation within the geothermal system allows the reservoir to sustain a 50-year production at a flow rate of 1050 t/h. The distance of 2 km, between the production and reinjection wells, is sufficient to prevent any thermal breakthrough within the estimated operational lifetime. OGS and FELFOW results are qualitatively very similar with differences in peak velocities and temperatures. The case study provides valuable guidelines for future exploitation of the CG-TA deep geothermal reservoir

    Finite dimensional corrections to mean field in a short-range p-spin glassy model

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    In this work we discuss a short range version of the pp-spin model. The model is provided with a parameter that allows to control the crossover with the mean field behaviour. We detect a discrepancy between the perturbative approach and numerical simulation. We attribute it to non-perturbative effects due to the finite probability that each particular realization of the disorder allows for the formation of regions where the system is less frustrated and locally freezes at a higher temperature.Comment: 18 pages, 5 figures, submitted to Phys Rev

    The effect of exercise on glucoregulatory hormones: A countermeasure to human aging: Insights from a comprehensive review of the literature

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    Hormones are secreted in a circadian rhythm, but also follow larger-scale timetables, such as monthly (hormones of the menstrual cycle), seasonal (i.e., winter, summer), and, ultimately, lifespan-related patterns. Several contexts modulate their secretion, such as genetics, lifestyle, environment, diet, and exercise. They play significant roles in human physiology, influencing growth of muscle, bone, and regulating metabolism. Exercise training alters hormone secretion, depending on the frequency, duration, intensity, and mode of training which has an impact on the magnitude of the secretion. However, there remains ambiguity over the effects of exercise training on certain hormones such as glucoregulatory hormones in aging adults. With advancing age, there are many alterations with the endocrine system, which may ultimately alter human physiology. Some recent studies have reported an anti-aging effect of exercise training on the endocrine system and especially cortisol, growth hormone and insulin. As such, this review examines the effects of endurance, interval, resistance and combined training on hormones (i.e., at rest and after) exercise in older individuals. We summarize the influence of age on glucoregulatory hormones, the influence of exercise training, and where possible, examine masters " athletes " endocrinological profile.Scopu

    2023 Update on Sepsis and Septic Shock in Adult Patients: Management in the Emergency Department

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    Background: Sepsis/septic shock is a life-threatening and time-dependent condition that requires timely management to reduce mortality. This review aims to update physicians with regard to the main pillars of treatment for this insidious condition. Methods: PubMed, Scopus, and EMBASE were searched from inception with special attention paid to November 2021–January 2023. Results: The management of sepsis/septic shock is challenging and involves different pathophysiological aspects, encompassing empirical antimicrobial treatment (which is promptly administered after microbial tests), fluid (crystalloids) replacement (to be established according to fluid tolerance and fluid responsiveness), and vasoactive agents (e.g., norepinephrine (NE)), which are employed to maintain mean arterial pressure above 65 mmHg and reduce the risk of fluid overload. In cases of refractory shock, vasopressin (rather than epinephrine) should be combined with NE to reach an acceptable level of pressure control. If mechanical ventilation is indicated, the tidal volume should be reduced from 10 to 6 mL/kg. Heparin is administered to prevent venous thromboembolism, and glycemic control is recommended. The efficacy of other treatments (e.g., proton-pump inhibitors, sodium bicarbonate, etc.) is largely debated, and such treatments might be used on a case-to-case basis. Conclusions: The management of sepsis/septic shock has significantly progressed in the last few years. Improving knowledge of the main therapeutic cornerstones of this challenging condition is crucial to achieve better patient outcomes
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