787 research outputs found
Histogram comparison as a powerful tool for the search of new physics at LHC. Application to CMSSM
We propose a rigorous and effective way to compare experimental and
theoretical histograms, incorporating the different sources of statistical and
systematic uncertainties. This is a useful tool to extract as much information
as possible from the comparison between experimental data with theoretical
simulations, optimizing the chances of identifying New Physics at the LHC. We
illustrate this by showing how a search in the CMSSM parameter space, using
Bayesian techniques, can effectively find the correct values of the CMSSM
parameters by comparing histograms of events with multijets + missing
transverse momentum displayed in the effective-mass variable. The procedure is
in fact very efficient to identify the true supersymmetric model, in the case
supersymmetry is really there and accessible to the LHC
Tidal circulation, sediment and pollutant transport in Cádiz Bay (SW Spain): A modelling study
A numerical model to simulate the dispersion of particle-reactive tracers in Cádiz Bay (SW Spain) has
been developed. It includes a hydrodynamic submodel to provide water currents, a sediment transport
submodel, which provides suspended matter concentrations and sedimentation rates and the pollutant
dispersion model. Pollutant exchanges between the liquid and solid phases are described in a dynamic
way, using kinetic transfer coefficients. Results of the hydrodynamic and sediment transport models have
been compared with observations. The contamination of sediments of the bay by fallout 137Cs has been
simulated. The existence of an accumulation area in the inner bay, found in field measurements, has been
reproduced by the model. Dispersion experiments for Zn and 226Ra have also been carried out. Flushing times of the inner bay have been finally determined through numerical experimentsMinisterio de Ciencia e Innovación CTM2009-14321-C02-01Ministerio de Ciencia e Innovación CTM2009-14321-C02-0
Parental Supervision: Predictive Variables of Positive Involvement in Cyberbullying Prevention
From an increasingly early age, parents face the challenge of educating their sons and daughters to act in the world of offline and online relationships. If for professional educators it is not proving easy, the involvement and guidance of parents in their children′s use of the internet seems to be a complex and unexplored challenge. This work aims to analyse the variables that influence digital education and determine a predictive model of positive parental involvement. This study was done with a representative sample consisting of five hundred and ninety-six families (596), representing the parents of children from schools with similar socio-cultural indexes. To do this, and using self-report instruments convertible into independent scales, four predictor variables were analysed: (1) parental knowledge of cyberbullying; (2) perception of parental competence in this regard; (3) parental perception of online risks; and (4) the attribution of parental responsibility in digital education. A structural equations model (SEM) examined the predictive value of these variables with respect to positive parental involvement. The structural equations model confirmed direct and mediated relationships between the independent and mediating variables on the dependent variable: parental supervision. The results indicate that positive parental involvement can be predicted from higher scores in parental knowledge of cyberbullying, perception of parental competence, risk adjustment, and attribution of parental responsibility
Fibra de carbono como material de interposición en defectos del cartílago de crecimiento: estudio experimental
El problema que plantean los traumatismos de cartílago de crecimiento, con
respecto al tratamiento de los puentes óseos y sus secuelas han motivado la realización del
presente trabajo experimental. Se ha pretendido valorar la utilidad de la fibra de carbono como
material de interposición en la prevención de la formación de puentes óseos tras una lesión
fisária distal femoral provocada quirúrgicamente. Se han utilizado 24 conejos, de ambos
sexos, de cuatro semanas de vida y un peso medio de 1.200 g distribuidos en cuatro grupos
de seis animales cada uno, según el momento de sacrificio, 1, 2, 4 y 8 semanas. Los animales
fueron intervenidos en ambos fémures realizándoles una resección externa de la placa de crecimiento
en la extremidad distal. El fémur izquierdo fue considerado como control, y en el
fémur derecho se implantó fibra de carbono en el defecto creado. Todos los especímenes fueron
estudiados macroscópica, radiológica, e histológicamente, observando que la fibra de carbono
utilizada como material de interposición en los defectos de cartílago de crecimiento, actúa
como barrera pasiva retrasando la aparición del puente óseo.The problem set forth by the traumatisms of growth cartilage regarding the treatment
of the osseus bridges and its sequelas has motivated the carrying out of an experimental
model in rabbit. It has been our pretension to evaluate the utility of the carbon fibre as a material
of insertion in the prevention of osseous bridges formation after a physeal distal femoral lesion
surgically provoked. 24 rabbits, of both sexes, 4 weeks old and with an average weight of 1.200
g have been used for this experiment. These have been distributed into 4 group composed
of 6 animals each, taking into account the moment of sacrifice, 1, 2, 4 and 8 weeks. Both
femurs of each animals were operated on executing an external resection of the growth plate
in distal extremity of the femur. The left femur was taken as control and was left to evolve.
A carbon fibre was implanted on the right femur, taken as experimental. All the specimen were
studied macroscopically, radiologically and histologically, observing that the carbon fibre used
as material of interposition in the defects growth cartilage sets as a passive barrier retarding
the appearance of the osseous bridges
Preliminary u isotopic data in the Cádiz coastal area (SW Spain) as proxy for coastal groundwater discharge
Peer Reviewe
SEU Tests Performed on the Digital Communication System for LHC Cryogenic Instrumentation
The future LHC particle accelerator will use a large number of cryogenic sensors and actuators, most of which are located inside the machine tunnel and therefore in a radiation environment. These elements will communicate through a fieldbus. This paper reports the irradiation study carried out on WorldFIP fieldbus communication system. A digital communication system based on WorldFIP fieldbus protocol has been implemented and Single Event Effects (SEE) and Total Ionizing Dose (TID) radiation tests have been performed on it
Myristic acid potentiates palmitic acid-induced lipotoxicity and steatohepatitis associated with lipodystrophy by sustaning de novo ceramide synthesis.
Palmitic acid (PA) induces hepatocyte apoptosis and fuels de novo ceramide synthesis in the endoplasmic reticulum (ER). Myristic acid (MA), a free fatty acid highly abundant in copra/palmist oils, is a predictor of nonalcoholic steatohepatitis (NASH) and stimulates ceramide synthesis. Here we investigated the synergism between MA and PA in ceramide synthesis, ER stress, lipotoxicity and NASH. Unlike PA, MA is not lipotoxic but potentiated PA-mediated lipoapoptosis, ER stress, caspase-3 activation and cytochrome c release in primary mouse hepatocytes (PMH). Moreover, MA kinetically sustained PA-induced total ceramide content by stimulating dehydroceramide desaturase and switched the ceramide profile from decreased to increased ceramide 14:0/ceramide16:0, without changing medium and long-chain ceramide species. PMH were more sensitive to equimolar ceramide14:0/ceramide16:0 exposure, which mimics the outcome of PA plus MA treatment on ceramide homeostasis, than to either ceramide alone. Treatment with myriocin to inhibit ceramide synthesis and tauroursodeoxycholic acid to prevent ER stress ameliorated PA plus MA induced apoptosis, similar to the protection afforded by the antioxidant BHA, the pan-caspase inhibitor z-VAD-Fmk and JNK inhibition. Moreover, ruthenium red protected PMH against PA and MA-induced cell death. Recapitulating in vitro findings, mice fed a diet enriched in PA plus MA exhibited lipodystrophy, hepatosplenomegaly, increased liver ceramide content and cholesterol levels, ER stress, liver damage, inflammation and fibrosis compared to mice fed diets enriched in PA or MA alone. The deleterious effects of PA plus MA-enriched diet were largely prevented by in vivo myriocin treatment. These findings indicate a causal link between ceramide synthesis and ER stress in lipotoxicity, and imply that the consumption of diets enriched in MA and PA can cause NASH associated with lipodystrophy
From floodplain to aquatic sediments: Radiogeochronological fingerprints in a sediment core from the mining impacted Sancho Reservoir (SW Spain)
The Sancho Reservoir (SW Spain) was built in 1962, about the time of maximum 137Cs fallout, and it has been affected by acid mine drainage (AMD) particularly since the mining cease in 2001. This is a unique scenario for studying the radiogeochronological fingerprints in AMD-affected sediments deposited over the former flood plain. A sediment core sampled in 2011 was analysed for bulk density, 137Cs, 239Pu, 240Pu, 210Pb, 226Ra, 228Ra, 234Th (238U) and 40K, and studied with various radiometric dating models. Bulk density revealed unsteady compaction and likely depositional events. The activity concentrations of 226Ra, 228Ra, 234Th (238U) and 40K were uniform down-core, but declining overall in the upper 0–25 cm, revealing changes in provenance except for 238U, which increased in the top 10 cm likely due to its supply by AMD. The AMD fingerprint was also found in the 239+240Pu/137Cs activity ratio, which increased in the top sediment layers. The 137Cs and 239+240Pu profiles show well defined peaks at the same depth, with inventories being about four times higher than the expected integrated atmospheric deposition in the area. The unsupported 210Pb (210Pbexc) showed a complex non-monotonic profile interrupted at several sections, particularly around the 137Cs peak. The whole dataset cannot be interpreted in terms of continuous sedimentation processes. Based upon correlated features in the bulk density and 210Pbexc profiles, a series of depositional events (likely linked to peaks in the rainfall records) have been identified in the core. These events date back to the period comprised since the construction of the dam until its increase in height in 1972, which likely displaced upstream the main depositional area of riverine loads, as inferred from sediment trap data. The CRS (with a reference date) and (a piecewise) CIC models have been used for complementing and discussing the chronology.Ministerio de Economia y Competitividad CTM2015-68628-
Signal Conditioning for Cryogenic Thermometry in the LHC
Temperature measurement is a key issue in the LHC, as it will be used to regulate the cooling of the superconducting magnets. The compromise between available cooling power and the coil superconducting characteristics leads to a restricted temperature control band, around 1.9 K. An absolute accuracy DeltaT < 10 mK below 2.2 K, and DeltaT < 5 K above 25 K, is necessary. For resistive thermometers covering the full temperature range, and having a negative dR/dT sensitivity, this is typically equivalent to a relative accuracy DeltaR/R of 3 10**-3 over 3 resistance decades. Also, to limit the thermometer's self-heating, the sensing current must be limited to few muA. Furthermore, the radiation levels next to the accelerator are expected to degrade significantly the performance of conventional analogue electronics. As these stringent requirements are not met by commercial conditioners, three different architectures have been developed at CERN. The first compresses the input dynamic range using a logarithmic transfer function; the second partitions the input range into three linear regions; the third converts resistance linearly into the frequency of a square wave. They fulfil the above specifications and provide industrial robustness in terms of thermal drift, galvanic protection, and compact packaging, while optimising cost-to-performance ratio. This paper describes the principles of their design, compares their characteristics and shows results of field tests. Future developmens include ASIC versions, Fieldbus interfacing, and radiation tolerant re-design
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