583 research outputs found

    How to Integrate Machine-Learning Probabilistic Output in Integer Linear Programming: a case for RSA

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    We integrate machine-learning-based QoT estimation in reach constraints of an integer linear program (ILP) for routing and spectrum assignment (RSA), and develop an iterative solution for QoT-aware RSA. Results show above 30% spectrum savings compared to solving RSA with ILP using traditional margined reach computation

    Dual-Stage Planning for Elastic Optical Networks Integrating Machine-Learning-Assisted QoT Estimation

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    Following the emergence of Elastic Optical Networks (EONs), Machine Learning (ML) has been intensively investigated as a promising methodology to address complex network management tasks, including, e.g., Quality of Transmission (QoT) estimation, fault management, and automatic adjustment of transmission parameters. Though several ML-based solutions for specific tasks have been proposed, how to integrate the outcome of such ML approaches inside Routing and Spectrum Assignment (RSA) models (which address the fundamental planning problem in EONs) is still an open research problem. In this study, we propose a dual-stage iterative RSA optimization framework that incorporates the QoT estimations provided by a ML regressor, used to define lightpaths' reach constraints, into a Mixed Integer Linear Programming (MILP) formulation. The first stage minimizes the overall spectrum occupation, whereas the second stage maximizes the minimum inter-channel spacing between neighbor channels, without increasing the overall spectrum occupation obtained in the previous stage. During the second stage, additional interference constraints are generated, and these constraints are then added to the MILP at the next iteration round to exclude those lightpaths combinations that would exhibit unacceptable QoT. Our illustrative numerical results on realistic EON instances show that the proposed ML-assisted framework achieves spectrum occupation savings up to 52.4% (around 33% on average) in comparison to a traditional MILP-based RSA framework that uses conservative reach constraints based on margined analytical models

    Jurassic calderas associated with Chon Aike formation volcanism near by Puesto Salado, east of Santa Cruz province, Argentina

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    A partir del levantamiento aeromagnético del Macizo del Deseado, se ha podido interpretar la presencia de dos conspicuas estructuras caldéricas de 30 y 23km de diámetro, separadas por una distancia de 7km, centradas en 48º52’S/68º02’O y 48º53’S/68º29’O, respectivamente, en el subsuelo de la región del Puesto Salado. Las calderas identificadas se asocian a las volcanitas de la Formación Chon Aike y son las primeras detectadas en el subsuelo en esta unidad, siendo estructuras análogas a las encontradas en unidades volcánicas equivalentes de la Patagonia. La profundidad estimada a la que se encuentran las estructuras caldéricas está en el rango de 350 a 550 m. En virtud de la dimensión de estas calderas se ha estimado que el volumen de material piroclástico eruptado por las mismas está en el orden de 1000Km3 para la caldera Puesto Salado oriental y de 200Km3 para la caldera Puesto Salado occidental. Las calderas del Puesto Salado se distinguen por sus dimensiones mayores con respecto a aquellas asociadas al volcanismo jurásico de la región extraandina de Santa Cruz. Con fines comparativos se realizaron algunas observaciones, acerca de las signaturas magnéticas de dos áreas vecinas de la secuencia volcánica-piroclástica jurásica de la Formación Chon Aike.The aeromagnetic survey of the Deseado Massif, Santa Cruz province, Argentina, has allowed to interpret the occurrence of two conspicuous caldera structures of 30 and 23 km in diameter, respectively centered at 48º 52’ S / 68º 02’ W and 48º 53’ S/ 68º 29’ W, i.e. located roughly about 7 km apart. The identified calderas –herein referred to as Puesto Salado calderas– are associated with the Chon Aike Jurassic acid volcanites which, although are locally covered by Cenozoic sediments, are largely spread in the southern Patagonian region. The estimated depth for the Puesto Salado caldera structures ranges 350 to 550 m; its dimension (diameter) is notably larger than that of other calderas associated with the Jurassic volcanism in the extra-Andean region of the Santa Cruz province. The possible volume of pyroclastic material erupted from the identified calderas has been estimated in terms of their dimension, ranging between 1000 km3 for the eastern Puesto Salado Caldera and 200 km3 for the western Puesto Salado caldera. Additionally, preliminary characterization of the magnetic signatures associated with the Jurassic volcanic-pyroclastic sequence of the Chon Aike Formation in two neighboring areas has been carried out for comparative purposes.Asociación Argentina de Geofísicos y Geodesta

    changes in aqueductal csf stroke volume and progression of symptoms in patients with unshunted idiopathic normal pressure hydrocephalus

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    BACKGROUND AND PURPOSE: Idiopathic normal pressure hydrocephalus (iNPH) represents a diagnostic challenge, given its variable presentation and progression. Stroke volume (SV), defined as the mean volume of CSF passing through the aqueduct during both systole and diastole, greater than or equal to 42 μL, serves as a selection criterion for patients with good probabilities of improvement after ventriculoperitoneal shunt surgery (VPS). In this study, we evaluated the changes in SV during the progression of clinical symptoms in patients with suspected NPH. MATERIALS AND METHODS: Nine patients who presented with clinical and radiologic evidence of NPH, but refused treatment with VPS, were evaluated every 6 months for up to 2 years for progression in their clinical symptoms and changes in their SV, as measured by phase-contrast cine MR imaging (PCCMR). RESULTS: SV seems to increase between the onset of the symptoms and the following 18 to 20 months, then seems to plateau, followed in the next 18 to 20 months by a slight decline, and finally to a more precipitous drop in the next 12 months. During this time, however, the patient9s clinical symptoms progressively worsen. CONCLUSION: Patients with a low SV have not necessarily had brain atrophy and can show, in the following months, a progressive increase in SV, which qualifies them as good candidates for VPS. The progressive reduction of the SV in untreated patients with worsening clinical symptoms may be a sign of a progressive cerebral ischemic injury, which renders the NPH irreversible

    Post-acute delivery of erythropoietin induces stroke recovery by promoting perilesional tissue remodelling and contralesional pyramidal tract plasticity

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    The promotion of post-ischaemic motor recovery remains a major challenge in clinical neurology. Recently, plasticity-promoting effects have been described for the growth factor erythropoietin in animal models of neurodegenerative diseases. To elucidate erythropoietin's effects in the post-acute ischaemic brain, we examined how this growth factor influences functional neurological recovery, perilesional tissue remodelling and axonal sprouting of the corticorubral and corticobulbar tracts, when administered intra-cerebroventricularly starting 3 days after 30 min of middle cerebral artery occlusion. Erythropoietin administered at 10 IU/day (but not at 1 IU/day), increased grip strength of the contralesional paretic forelimb and improved motor coordination without influencing spontaneous locomotor activity and exploration behaviour. Neurological recovery by erythropoietin was associated with structural remodelling of ischaemic brain tissue, reflected by enhanced neuronal survival, increased angiogenesis and decreased reactive astrogliosis that resulted in reduced scar formation. Enhanced axonal sprouting from the ipsilesional pyramidal tract into the brainstem was observed in vehicle-treated ischaemic compared with non-ischaemic animals, as shown by injection of dextran amines into both motor cortices. Despite successful remodelling of the perilesional tissue, erythropoietin enhanced axonal sprouting of the contralesional, but not ipsilesional pyramidal tract at the level of the red and facial nuclei. Moreover, molecular biological and histochemical studies revealed broad anti-inflammatory effects of erythropoietin in both hemispheres together with expression changes of plasticity-related molecules that facilitated contralesional axonal growth. Our study establishes a plasticity-promoting effect of erythropoietin after stroke, indicating that erythropoietin acts via recruitment of contralesional rather than of ipsilesional pyramidal tract projection

    Peat soil burning in the Mezzano lowland (Po Plain, Italy): triggering mechanisms and environmental consequences.

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    The effects of peat burning on organic-rich agricultural soils of the Mezzano Lowland (NE Italy) were evaluated on soil profiles variously affected by smoldering. Profiles were investigated for pH, electrical conductivity, bulk density, elemental and isotopic composition of distinct carbon (and nitrogen) fractions. The results suggest that the horizons affected by carbon loss lie at depths 10–70 cm, where the highest temperatures are developed. We suggest that the exothermal oxidation of methane (mediated by biological activity) plays a significant role in the triggering mechanism. In the interested soils we estimated a potential loss of Soil Organic Carbon of approximately 110 kg m−2 within the first meter, corresponding to 580 kg CO2 m−3. The released greenhouse gas is coupled with a loss of soil structure and nutrients. Moreover, the process plausibly triggers mobility of metals bound in organometallic complexes. All these consequences negatively affect the environment, the agricultural activities and possibly also health of the local people

    IPSC-derived neural stem cells act via kinase inhibition to exert neuroprotective effects in spinal muscular atrophy with respiratory distress type 1

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    Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a motor neuron disease caused by mutations in the IGHMBP2 gene, without a cure. Here, we demonstrate that neural stem cells (NSCs) from human-induced pluripotent stem cells (iPSCs) have therapeutic potential in the context of SMARD1. We show that upon transplantation NSCs can appropriately engraft and differentiate in the spinal cord of SMARD1 animals, ameliorating their phenotype, by protecting their endogenous motor neurons. To evaluate the effect of NSCs in the context of human disease, we generated human SMARD1-iPSCs motor neurons that had a significantly reduced survival and axon length. Notably, the coculture with NSCs ameliorate these disease features, an effect attributable to the production of neurotrophic factors and their dual inhibition of GSK-3 and HGK kinases. Our data support the role of iPSC as SMARD1 disease model and their translational potential for therapies in motor neuron disorders

    Origin of fluoride and arsenic in the main ethiopian rift waters

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    In the Main Ethiopian Rift (MER) area, rural populations often use water that exceeds the World Health Organization thresholds for fluoride (F–) and arsenic (As), two elements that are hazardous for human health. In this study, twenty-nine water samples were collected from lakes and hot and cold springs in southern MER to investigate source(s) and health-risk of the F– and As contamination. According to major ion and trace element analyses, only cold spring water is safe for consumption, whereas hot spring water is the most contaminated. Leaching tests performed with the MER rhyolitic volcanic rocks and their weathered products (fluvio-lacustrine sediments) demonstrate that the main cause of the F– and As release is geogenic, i.e., not related to anthropogenic activities. The weathering of volcanic glass and minerals (apatites, clays, hydro-oxides) by CO2-bearing alkaline water induces the mobilisation of F– and As from solid to liquid phase. This process is particularly fast, when fluvio-lacustrine sediments are involved, and can be further enhanced by hot groundwater leaching. This study, investigating the distribution, sources, and mechanisms of F– and As release in MER water, could be of interest also for other sectors of the East African Rift and other similar volcano-tectonic settings

    Soil carbon investigation in three pedoclimatic and agronomic settings of northern Italy

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    Sustainable agricultural management is needed to promote carbon (C) sequestration in soil, prevent loss of soil fertility, and reduce the release of greenhouse gases. However, the influence of agronomic practices on soil C sequestration depends on the existing pedoclimatic features. We characterized the soils of three farms far away each other in the Emilia-Romagna region (Northern Italy): an organic farm in the Northern Apennines, a biodynamic farm, and a conventional farm on the Po Plain. The total, inorganic, and organic carbon in soil, as well as the distinct humic fractions were investigated, analyzing both the elemental and isotopic (13C/12C) composition. In soils, organic matter appears to be variously affected by mineralization processes induced by microorganisms that consume organic carbon. In particular, organic carbon declined in farms located in the plain (e.g., organic carbon down to 0.75 wt%; carbon stock0-30 cm down to 33 Mg/ha), because of the warmer climate and moderately alkaline environment that enhance soil microbial activity. On the other hand, at the mountain farm, the minimum soil disturbance, the cold climate, and the neutral conditions favored soil C sequestration (organic carbon up to 4.42 wt%; carbon stock0-30 cm up to 160 Mg/ha) in humified organic compounds with long turnover, which can limit greenhouse gas emissions into the atmosphere. This work shows the need for thorough soil investigations, to propose tailored best-practices that can reconcile productivity and soil sustainability

    Chemical characterisation of construction and demolitionwaste in Skopje city and its surroundings (Republic of Macedonia)

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    In the Republic of Macedonia, construction and demolition waste is often dumped, underestimating the potential recycling and re-use as raw materials for civil engineering works and/or cement/ceramic industries. SAMCODE (Sustainable Approach to Managing Construction and Demolition Waste) is a know-how exchange program, the focus of which is chemical characterisation in terms of major and trace elements in order to evaluate the possible Macedonian construction and demolition waste recycling. Thirty-nine waste samples were collected from different dumps in Skopje and surroundings. X-ray fluorescence analyses, carried out on powdered samples, show i) highly variable concentrations, indicative of the heterogenous nature of construction and demolition waste, and ii) high concentration in Cr, Ni, and Zn with respect to Italian, Chinese, and Dutch tolerance limits, probably due to the presence of these elements in ophiolitic rocks and sulphide-bearing deposits, used as raw material in building activity. Inductively coupled plasma mass spectrometry analyses of leachates, performed to assess the mobility of heavy metals, show significant concentrations of Cr, and to a lesser extent, Ni. Results suggest that homogenisation processes of the recycled materials should be implemented and preliminary screening of construction and demolition waste should be performed to eliminate heavy metals-bearing components
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