We present preliminary experimental observations of the collision processes between two orthogonal laser produced plasmas in a low pressure neutral gas background. A Nd:YAG laser, 340 mJ, 3.5 ns, at ...1.06 μm, operating at 10 Hz, is used in the experiments. The main laser beam is divided in two beams by a 50% beam splitter, and then focused over two rotating graphite targets, with characteristic fluence 3.5 J cm2. Experiments are conducted in a range from a base pressure of 0.3 mTorr, up to 50 mTorr argon. The dynamics of the laser plasmas is characterized by time resolved and time integrated optical emission spectroscopy (OES), with 20 ns and 10 ms time resolution, and 50 ns time resolved plasma imaging of visible plasma emission. Clear effects of the neutral gas background on the postcollision plasma dynamics are identified. The overall dynamics of the post-collision plasma is found to be consistent with high collisionality of the carbon plasma plumes, which results in full stagnation on collisioning.
Study of ATLAS sensitivity to FCNC top decays Carvalho, J.; Castro, N.; Chikovani, L. ...
The European physical journal. C, Particles and fields,
12/2007, Letnik:
52, Številka:
4
Journal Article
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The ATLAS experiment sensitivity to top quark flavour changing neutral current (FCNC) decays was studied at LHC using tt̄ events. While one of the top quarks is expected to follow the dominant ...Standard Model decay t→bW, the other decays through a FCNC channel, i.e. t→Zu(c), t→γu(c) or t→gu(c). Different types of analyses, applied to each FCNC decay mode, were compared. The FCNC branching ratio sensitivity (assuming a 5σ signal significance) and 95% confidence level limits on the branching ratios (in the hypothesis of signal absence) were obtained.
The calculated position resolutions for X-ray photons (1–60 keV) in pure noble gases at atmospheric pressure are presented. In this work we show the influence of the atomic shells and the detector ...dimensions on the intrinsic position resolution of the used noble gas. The calculated results were obtained by using a new software tool, Degrad, and compared to the available experimental data.
► We examine carefully screened patent database in auto emission control technology. ► Performance-based technology-forcing (PBTF) regulation stimulates innovation. ► Both automakers and component ...suppliers innovated under the PBTF regulation. ► PBTF regulation temporarily induced domestic U.S. firms become more innovative.
This article uses a carefully screened patent database in automobile emission control technologies and a detailed regulatory action analysis to examine firms’ innovation in response to U.S. technology-forcing auto emissions standards enacted between 1970 and 1998. The study finds that under the
performance-based technology-forcing (PBTF) auto emissions regulations, both automakers and component suppliers innovated and introduced more advanced emission control technologies for automobile applications. The study also shows that stringent PBTF regulation temporarily induced domestic U.S. firms to become more innovative than foreign firms that operated in the local U.S. market during the early phase of the regulatory regime. Findings of this research strongly imply that government intervention in the form of technology-forcing regulation can drive firms to invest in technological innovation.
ABSTRACT The Cerrado biome has presented challenges in reconciling its agricultural expansion with water availability. In this sense, water resources planning and management are fundamental for the ...economic, social, and environmental development of the Cerrado biome, which has been hampered by the lack of data, especially those referring to irrigation strategies, such as, for example, the water retention curve. The water retention curve is essential to understand water dynamics in the soil; however, obtaining it can be laborious, opening an opportunity for Pedotransfer Functions (PTFs). The current study aimed to develop and evaluate PTFs to estimate the fit parameters of the van Genuchten model for the Cerrado biome. Multiple Linear Regression (MLR) and four machine learning (ML) algorithms were used to develop the PTFs. The ML algorithms were the Multivariate Adaptive Regression Splines (MARS), Random Forest (RF), Support Vector Regression (SVR), and K Nearest Neighbors (KNN). Two combinations of soil data were evaluated, and the predictor variables used in each set were different. Using the RF and SVR models, the best estimates were obtained concerning the parameter θs (saturated water content). As for θr (residual water content), the models showed a moderate predictive capacity. For the other parameters, the models did not perform satisfactorily for α and n (fit parameters).
RESUMO O bioma Cerrado tem apresentado desafios em conciliar sua expansão agrícola com a disponibilidade hídrica. Nesse sentido, o planejamento e o manejo de recursos hídricos são fundamentais para o desenvolvimento econômico, social e ambiental do bioma Cerrado, que tem sido prejudicado pela carência de dados, especialmente aqueles referentes às estratégias de irrigação, como, por exemplo, as curvas de retenção de água, essencial para compreender a dinâmica de água no solo. Contudo, como sua obtenção pode ser trabalhosa, seus parâmetros podem ser estimados indiretamente via Funções de Pedotransferência (FPTs). O objetivo do presente estudo foi desenvolver e avaliar FPTs para estimar parâmetros do modelo de van Genuchten, usado para descrever o processo de retenção de água, para o bioma Cerrado. Para o desenvolvimento das FPTs, foram usados os métodos de Regressão Linear Múltipla (RLM) e quatro algoritmos de aprendizado de máquina: Multivariate Adaptative Regression Splines (MARS), Random Forest (RF), Support Vector Regression (SVR) e K Nearest Neightbors (KNN). Dados de solo de duas localidades foram utilizados, sendo que as variáveis preditoras selecionadas em cada conjunto foram diferentes. As melhores estimativas foram obtidas para o parâmetro θs (umidade de saturação), com destaque para os modelos RF e SVR. Já para a θr (umidade residual), os modelos apresentaram uma capacidade preditiva moderada. Para os demais parâmetros, os modelos não apresentaram um desempenho satisfatório para α e n (parâmetros de ajuste).
Background: Cryopreservation preserves cellular viability under low temperatures, resulting in diminished intracellular enzymatic activity and reduced cellular metabolism that ultimately allows ...preserving genetic material for indefinite periods of time. Embryos submitted to cryopreservation suffer from considerable morphological and functional damage, resulting in reduced survival and development rates. Objective: To evaluate pregnancy and delivery rates of in vitro-produced (IVP) Nellore (Bos indicus) embryos after vitrification under field conditions. Methods: The IVP embryos at blastocyst (Bl) and expanded blastocyst (Bx) were transferred fresh (n= 137) or after vitrification (n= 127). Results: Pregnancy rates at 35 d for fresh embryos were lower in Bl (41.6) than in Bx (60.9) (p0.05). Pregnancy loss at 60 d were similar (p>0.05) for both fresh (Bl: 3.1 and Bx: 4.8) and vitrified embryos (Bl: 1.9 and Bx: 4.7). Delivery rates were similar between groups (p>0.05). Conclusion: Both pregnancy and delivery rates of Bos indicus IVP embryos vitrified under field conditions are indistinguishable from fresh embryos.Key words: cattle reproduction, cryobiology, cryoinjury, cryotolerance, embryo surplus, embryo transfer. Resumen Antecedentes: La criopreservación se caracteriza por el mantenimiento de la viabilidad celular a bajas temperaturas, resultando en reducido metabolismo y actividad enzimática intracelular, lo que permite la preservación del material genético por períodos de tiempo indefinidos. Los embriones sometidos a ésta técnica sufren daños morfológicos y funcionales considerables, dando como resultado una sobrevivencia y tasas de desarrollo reducidas. Objetivo: Evaluar la tasa de preñez a partir de embriones Nelore (Bos indicus) producidos in vitro (IVP) después de la vitrificación bajo condiciones de campo. Métodos: Embriones IVP en los estadios de blastocisto (Bl) y blastocisto expandido (Bx) se transfirieron en fresco (n= 137) o después de la vitrificación (n= 127). Resultados: La tasa de preñez a los 35 d fue menor para los embriones transferidos en fresco en fase Bl (41,6) en relación con los Bx (60,9) (p0,05). Las pérdidas de preñez a los 60 d fueron similares (p>0,05) tanto para embriones en fresco en Bl (3,1) y Bx (4,8) como para los vitrificados (Bl: 1,9 y Bx: 4,7). Las tasas de nacimiento fueron similares entre los grupos (p>0,05). Conclusión: Las tasas de preñez y nacimiento de embriones IVP vitrificados de Nelore (Bos indicus) bajo condiciones de campo son semejantes a las de embriones en fresco.Palabras clave: criobiología, crioinjuria, criotolerancia, embriones sobrantes, reproducción de ganado, transferencia de embriones. Resumo Antecedentes: A criopreservação é caracterizada pela manutenção da viabilidade celular em baixas temperaturas, resultando em atividade enzimática intracelular e metabolismo celular reduzido, que permite a preservação do material genético por períodos indefinidos de tempo. Embriões submetidos à criopreservação sofrem danos morfológicos e funcionais consideráveis, resultando em sobrevivência reduzida e menores taxas de desenvolvimento. Objetivo: Avaliar a taxa de prenhez a partir de embriões Nelore (Bos indicus) produzidos in vitro (IVP) após a vitrificação sob condições de campo. Métodos: Embriões IVP nos estádios de blastocisto (Bl) e blastocisto expandido (Bx) foram transferidos a fresco (n= 137) ou depois da vitrificação (n= 127). Resultados: A taxa de prenhez aos 35 d foi menor para os embriões transferidos a fresco na fase de Bl (41,6), em relação aos Bx (60,9) (p0,05). As perdas de prenhez aos 60 d foram semelhantes (p>0,05) tanto para embriões a fresco nos estádios de Bl (3,1) e Bx (4,8), e vitrificados em Bl (1,9) e Bx (4,7). As taxas de nascimentos foram semelhantes entre os grupos (p>0,05). Conclusão: As taxas de prenhez e nascimentos dos embriões IVP vitrificados de Nelore (Bos indicus) sob condições de campo é semelhante àquela dos embriões a fresco.Palavras-chave: criobiologia, crioinjúria, criotolerância, embriões excedentes, reprodução de gado, transferência de embriões.
Accelerator-driven systems (ADSs) are investigated for long-lived fission product transmutation and fuel regeneration. The aim of this paper is to investigate the nuclear fuel evolution and the ...neutronic parameters of a lead-cooled accelerator-driven system used for fuel breeding. The fuel used in some fuel rods was T232hO2 for U233 production. In the other fuel rods was used a mixture based upon Pu-MA, removed from PWR-spent fuel, reprocessed by GANEX, and finally spiked with thorium or depleted uranium. The use of reprocessed fuel ensured the use of T232hO2 without the initial requirement of U233 enrichment. In this paper was used the Monte Carlo code MCNPX 2.6.0 that presents the depletion/burnup capability, combining an ADS source and kcode-mode (for criticality calculations). The multiplication factor (keff) evolution, the neutron energy spectra in the core at BOL, and the nuclear fuel evolution during the burnup were evaluated. The results indicated that the combined use of T232hO2 and reprocessed fuel allowed U233 production without the initial requirement of U233 enrichment.
We are developing large size THick GEM (THGEM)-based detectors of single photons, mainly meant for Cherenkov imaging applications. The R&D programme includes the complete characterisation of the ...THGEM electron multipliers, the study of the aspects related to the detection of single photons and the engineering towards large size detector prototypes. Our most recent achievements include dedicated studies concerning the ion backflow to the photocathode; relevant progress in the engineering aspects, in particularly related to the production of large-size THGEMs, where the strict correlation between the local gain-value and the local thickness-value has been demonstrated and a 300300 mm super(2) active area detector has been successfully operated at the CERN PS T10 test beam; the introduction of a new hybrid detector architecture, offering promising performance, which is formed by a THGEM layer which acts both as photocathode and pre-amplification device, followed by a MICROMEGAS (MM) multiplication stage. We report about the general status of the R&D programme and, in detail, about the recent progress.
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