6,786 research outputs found

    Evaporation Channel as a Tool to Study Fission Dynamics

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    The dynamics of the fission process is expected to affect the evaporation residue cross section because of the fission hindrance due to the nuclear viscosity. Systems of intermediate fissility constitute a suitable environment for testing such hypothesis, since they are characterized by evaporation residue cross sections comparable or larger than the fission ones. Observables related to emitted charged particle, due to their relatively high emission probability, can be used to put stringent constraints on models describing the excited nucleus decay and to recognize the effects of fission dynamics. In this work model simulations are compared with the experimental data collected via the ^{32}S + ^{100}Mo reaction at E_{lab}= 200 MeV. By comparing an extended set of evaporation channel observables the limits of the statistical model and the large improvement coming by using a dynamical model are evidenced. The importance of using a large angular covering apparatus to extract the observable is stressed. The opportunity to measure more sensitive observables by a new detection device in operation at LNL are also discussed.Comment: v1: 7 pages, 6 figure

    Gait Velocity Estimation using time interleaved between Consecutive Passive IR Sensor Activations

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    Gait velocity has been consistently shown to be an important indicator and predictor of health status, especially in older adults. It is often assessed clinically, but the assessments occur infrequently and do not allow optimal detection of key health changes when they occur. In this paper, we show that the time gap between activations of a pair of Passive Infrared (PIR) motion sensors installed in the consecutively visited room pair carry rich latent information about a person's gait velocity. We name this time gap transition time and show that despite a six second refractory period of the PIR sensors, transition time can be used to obtain an accurate representation of gait velocity. Using a Support Vector Regression (SVR) approach to model the relationship between transition time and gait velocity, we show that gait velocity can be estimated with an average error less than 2.5 cm/sec. This is demonstrated with data collected over a 5 year period from 74 older adults monitored in their own homes. This method is simple and cost effective and has advantages over competing approaches such as: obtaining 20 to 100x more gait velocity measurements per day and offering the fusion of location-specific information with time stamped gait estimates. These advantages allow stable estimates of gait parameters (maximum or average speed, variability) at shorter time scales than current approaches. This also provides a pervasive in-home method for context-aware gait velocity sensing that allows for monitoring of gait trajectories in space and time

    Electrical transport across Au/Nb:SrTiO3 Schottky interface with different Nb doping

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    We have investigated electron transport in Nb doped SrTiO3_3 single crystals for two doping densities. We find that the resistivity and mobility are temperature dependent in both whereas the carrier concentration is almost temperature invariant. We rationalize this using the hydrogenic theory for shallow donors. Further, we probe electrical transport across Schottky interfaces of Au on TiO2_2 terminated n-type SrTiO3_3. Quantitative analysis of macroscopic I-V measurements reveal thermionic emission dominated transport for the low doped substrate whereas it deviates from such behavior for the high doped substrate. This work is relevant for designing devices to study electronic transport using oxide-semiconductors.Comment: 10 Pages, 3 Figure

    Radiation Balance and Production of Forage Crops in a Mediterranean Region

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    This study is devoted to measure the radiation use efficiency (RUE) and the extinction light coefficient (k) of a sainfoin crop, cultivated in a site of Southern Italy. The same parameters are measured also for the global solar radiation (in this case kg and RUEg, respectively). The crop was maintened in well watered conditions and the measures were carried out during four cut cycles, one during 1994 and three during 1995. Transmitted, incident, soil and canopy reflected radiations were measured continously during the growth season. The results were given a mean of 2.61 and 1.2 g MJ-1 for RUE and RUEg, respectively and 0.86 and 0.71 for k and kg, respectively. These values, comparable with other similar results, confirm the good adaption of this forage crop to the Mediterranean conditions

    Poverty and Patterns of Growth

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    "We use a recently constructed cross-country data set on absolute poverty to examine whether there is regional and sectoral variation in the relationship between poverty and economic growth. We find that the povertygrowth linkage is strongest in East Asia and that this linkage is essentially driven by growth in the industrial sector. By contrast, in Latin America, South Asia, and Sub-Saharan Africa, agriculture has had a greater impact on poverty reduction. We argue that these results should not be interpreted to mean that all regions other than East Asia need to emphasize agriculture to reduce poverty. Rather, these countries - especially labor-abundant ones such as those of South Asia - should attempt to improve their policy and institutional environments that stand in the way of their exploiting their comparative advantage in labor-intensive industries and bringing about a rapid reduction in poverty.

    Comparison of hot-electron transmission in ferromagnetic Ni on epitaxial and polycrystalline Schottky interfaces

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    The hot-electron attenuation length in Ni is measured as a function of energy across two different Schottky interfaces viz. a polycrystalline Si(111)/Au and an epitaxial Si(111)/NiSi_2 interface using ballistic electron emission microscopy (BEEM). For similarly prepared Si(111) substrates and identical Ni thickness, the BEEM transmission is found to be lower for the polycrystalline interface than for the epitaxial interface. However, in both cases, the hot-electron attenuation length in Ni is found to be the same. This is elucidated by the temperature-independent inelastic scattering, transmission probabilities across the Schottky interface, and scattering at dissimilar interfaces.Comment: 5 pages, 5 figure
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