457 research outputs found
Transport Problems and Disintegration Maps
By disintegration of transport plans it is introduced the notion of transport
class. This allows to consider the Monge problem as a particular case of the
Kantorovich transport problem, once a transport class is fixed. The transport
problem constrained to a fixed transport class is equivalent to an abstract
Monge problem over a Wasserstein space of probability measures. Concerning
solvability of this kind of constrained problems, it turns out that in some
sense the Monge problem corresponds to a lucky case
Analytical Model of Thermo-electrical Behaviour in Superconducting Resistive Core Cables
High field superconducting NbSn accelerators magnets above 14 T, for future High Energy Physics applications, call for improvements in the design of the protection system against resistive transitions. The longitudinal quench propagation velocity (vq) is one of the parameters defining the requirements of the protection. Up to now vq has been always considered as a physical parameter defined by the operating conditions (the bath temperature, cooling conditions, the magnetic field and the over all current density) and the type of superconductor and stabilizer used. It is possible to enhance the quench propagation velocity by segregating a percent of the stabilizer into the core, although keeping the total amount constant and tuning the contact resistance between the superconducting strands and the core. Analytical model and computer simulations are presented to explain the phenomenon. The consequences with respect to minimum quench energy are evidenced and the strategy to optimize the cable designed is discussed
Stability Analysis of the LHC Cables for Transient Heat Depositions
The commissioning and the exploitation of the LHC require a good knowledge of the stability margins of the superconducting magnets with respect to beam induced heat depositions. Previous studies showed that simple numerical models are suitable to carry out stability calculations of multi-strands cables, and highlighted the relevance of the heat transfer model with the surrounding helium. In this paper we present a systematic scan of the stability margin of all types of LHC cables working at 1.9 Kagainst transient heat depositions. We specifically discuss the dependence of the stability margin on the parameters of the model, which provide an estimate of the uncertainty of the values quoted. The stability margin calculations have been performed using a zero-dimensional (0-D) numerical model, and a cooling model taking into account the relevant helium phases which may appear during a stability experiment: it includes Kapitza thermal resistance in superfluid He, boundary layer formation and heat transfer in He I, and considers the transition from nucleating boiling to film boiling during He gas formation
Amyotrophic Lateral Sclerosis and Air Pollutants in the Province of Ferrara, Northern Italy: An Ecological Study
The etiopathogenesis of amyotrophic lateral sclerosis (ALS) is still largely unknown, but likely depends on gene-environment interactions. Among the putative sources of environmental exposure are air pollutants and especially heavy metals. We aimed to investigate the relationship between ALS density and the concentration of air pollution heavy metals in Ferrara, northern Italy. An ecological study was designed to correlate the map of ALS distribution and that of air pollutants. All ALS cases diagnosed between 2000 and 2017 (Ferrara University Hospital administrative data) were plotted by residency in 100 sub-areas, and grouped in 4 sectors: urban, rural, northwestern and along the motorway. The concentrations of silver, aluminium, cadmium, chrome, copper, iron, manganese, lead, and selenium in moss and lichens were measured and monitored in 2006 and 2011. Based on 62 ALS patients, a strong and direct correlation of ALS density was observed only with copper concentrations in all sectors and in both sexes (Pearson coefficient (ρ) = 0.758; p = 0.000002). The correlation was higher in the urban sector (ρ = 0.767; p = 0.000128), in women for the overall population (ρ = 0.782, p = 0.000028) and in the urban (ρ = 0.872, p = 0.000047) population, and for the older cohort of diagnosed patients (2000-2009) the assessment correlated with the first assessment of air pollutants in 2006 (ρ = 0.724, p = 0.008). Our data is, in part, consistent with a hypothesis linking copper pollution to ALS
Carbon Dioxide degassing at Latera caldera (Italy): evidence of geothermal reservoir and evaluation of its potential energy
In order to test the potentiality of soil CO2 diffuse degassing measurements for the study of underground mass and heat transfer in geothermal systems detailed surveys were performed at Latera Caldera which is an excellent test site, due to the abundant available subsurface data. Over 2500 measurements of soil CO2 flux revealed that endogenous CO2 at Latera Caldera concentrates on a NE-SW band coinciding with a structural high of fractured Mesozoic limestones hosting a water-dominated high-enthalpy geothermal reservoir. The total hydrothermal CO2 degassing from the structural high has been evaluated at 350 t d-1 from an area of 3.1 km2. It has been estimated that such a CO2 release would imply a geothermal liquid flux of 263 kg s-1, with a heat release of 239 MW. The chemical and isotopic composition of the gas indicates a provenance from the geothermal reservoir and that CO2 is partly originated by thermal metamorphic decarbonation in the hottest deepest parts of the system and partly has a likely mantle origin. The ratios of CO2, H2, CH2 and CO to Ar, were used to estimate the T-P conditions of the reservoir. Results cluster at T ~ 200-300°C and PCO2 ~ 100-200 bars, close to the actual well measurements. Finally the approach proved to be an excellent tool to investigate the presence of an active geothermal reservoir at depth and that the H2-CO2-CH4-CO-Ar gas composition is a useful T-P geochemical indicator for such CO2 rich geothermal systems
Tomograms and other transforms. A unified view
A general framework is presented which unifies the treatment of wavelet-like,
quasidistribution, and tomographic transforms. Explicit formulas relating the
three types of transforms are obtained. The case of transforms associated to
the symplectic and affine groups is treated in some detail. Special emphasis is
given to the properties of the scale-time and scale-frequency tomograms.
Tomograms are interpreted as a tool to sample the signal space by a family of
curves or as the matrix element of a projector.Comment: 19 pages latex, submitted to J. Phys. A: Math and Ge
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Multi-Institutional Outcomes of Minimally Invasive Harvest of Rectal Mucosa Graft for Anterior Urethral Reconstruction.
PurposeWe report multi-institutional outcomes in patients who underwent urethroplasty with a rectal mucosa graft.Materials and methodsWe used the TURNS (Trauma and Urologic Reconstructive Network of Surgeons) database to identify patients who underwent urethral reconstruction with transanal harvest of a rectal mucosa graft. We reviewed preoperative demographics, stricture etiology, previous management and patient outcomes.ResultsWe identified 13 patients from April 2013 to June 2017. Median age at surgery was 54 years. The stricture etiology was lichen sclerosus in 6 of 13 patients (46%), idiopathic in 2 (15%), hypospadias in 1 (7%), prior gender confirming surgery in 3 (23%) and rectourethral fistula after radiation for prostate cancer in 1 (7%). Prior procedures included failed urethroplasty with a buccal mucosa graft in 9 of 13 patients (69%), direct vision internal urethrotomy in 2 (15%) and none in 2 (15%). Median stricture length was 13 cm. Stricture location in the 9 cisgender patients was panurethral in 5 (56%), bulbopendulous in 2 (22%) and bulbar in 2 (22%). It was located at the junction of the fixed urethra extending into the neophallus in all 3 patients (100%) who underwent prior gender confirming surgery. Mean rectal mucosa graft length for urethroplasty was 10.6 cm (range 3 to 16). Repair types included dorsal or ventral onlay, or 2-stage repair. Stricture recurred at a median followup of 13.5 months in 2 of 13 patients (15%). Postoperative complications included glans dehiscence, urethrocutaneous fistula and compartment syndrome in 1 patient each (7%). No rectal or bowel related complications were reported.ConclusionsUrethral reconstruction with a transanal harvested rectal mucosa graft is a safe technique when a buccal mucosa graft is unavailable or not indicated
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