1,596 research outputs found
Black-body radiation induced correlated excitation of Potassium Rydberg atoms in tweezer arrays
The orienteering problem: A hybrid control Formulation
In the last years, a growing number of challenging applications in navigation, logistics, and tourism were modeled as orienteering problems. This problem has been proposed in relation to a sport race where certain control points must be visited in a minimal time. In a certain kind of these competitions, the choice of the number and the order for the control points are left to the competitor. We propose an original approach to solve the orienteering problem based on hybrid control. The continuous state of the system contains information about the navigation toward the next control point. In contrast, the discrete state keeps track of the already visited ones. The control problem is solved using non-standard dynamical programming techniques
Advanced least weight design optimization of additive manufactured space rover steering brackets
Evolution of sea-surface temperature in the tropical Atlantic Ocean during FGGE, 1979: II. Oceanographic fields and heat balance of the mixed layer
Surface meteorological and surface and subsurface oceanographic data collected during 1979 are used to describe sea-surface temperature, mixed layer depth, zonal current component and net oceanic heat gain fields and to estimate the terms in a heat balance relation for the mixed layer. The terms are evaluated monthly on a 6° of latitude by 10° of longitude grid which covers the equatorial Atlantic from 9S to 9N. The first balance tested is between changes in mixed layer temperature and surface energy fluxes. These fluxes can account for more than 75% of the variance in the original time series of the quadrangles along 6S. Variance reductions are less, along 0° (order of 50%) and 6N (less than 25%). The addition of zonal advection improves some of the predictions but not significantly. Low variance reductions along 6N, west of 20W are attributed to the uncertainties in the estimates of observed temperature change and surface fluxes. The small variance reductions east of 20W, at 6N and along 0° may be related to the neglect of coastal and equatorial upwelling and meridional advection. A simple model is proposed which assumes an annual cycle for the intensity of mixing across the base of the mixed layer, most intense during summer, least intense during winter. Variance reductions at 0°, 5W increase from 20% to 60% with the inclusion of mixing. Meridional advection may also account for a portion of the observed variability in mixed layer temperature
Evolution of the near-surface thermal structure in the western Indian Ocean during FGGE, 1979
The evolution of mixed layer temperature (taken as sea-surface temperature, SST) in the western Indian Ocean north of 20S and west of 80E during the First GARP Global Experiment (FGGE), 1979 is described and modelled. The FGGE-year development in time and space of SST is compared to the appropriate climatology. FGGE events occurred in phase with climatology, but some amplitude anomalies were observed. Heat budget computations for the surface mixed layer indicate that over 25% of the region studied energy fluxes through the sea surface can account for 80% of the observed SST variance. South of the equator, 80% of the variance is accounted for in 36% of the area and north, only 11%. Exceptions are noted along the western boundary, in the central and eastern Arabian Sea, and in a band south of the equator between 6S and 12S, east of 60E. The addition of entrainment through the base of the mixed layer improves the heat budget estimates over most of the region, in particular, along the Arabian coast. Near the northern part of the coast of east Africa, however, inclusion of the effect of horizontal advection gives more improvement. The breakdown of the heat budget computations in the central and eastern Arabian Sea and in the band south of the equator is attributed to a small signal in SST variance and few data in the regions
Validation of a new data-analysis software for multiple-peak analysis of γ spectra at ISIS pulsed Neutron and Muon Source
© 2019 Elsevier B.V. In this work, we present a multi-peak fitting code in order to establish a new protocol for the analysis of γ spectra at ISIS pulsed Neutron and Muon Source. The protocol, relying on the ROOT framework developed at CERN, has been tailored for the analysis of two specific gamma emitters – 241Am and 133Ba – and its results have been compared to those generated by Hypermet PC, a dedicated software package specifically devoted to the analysis of neutron induced γ-ray spectra and of widespread use since late 1990s. This new fitting procedure is scheduled for integration into the software for time-resolved prompt-gamma activation analysis, T-PGAA, currently under development at ISIS. T-PGAA allows for the simultaneous acquisition of photon energy and neutron time of flight, respectively, when prompt gamma rays are emitted by a sample after neutron absorption, essentially combining neutron resonance capture analysis (NRCA) and prompt gamma activation analysis (PGAA)
Free-ranging livestock and a diverse landscape structure increase bat foraging in mountainous landscapes
Traditional farming, where livestock is seasonally managed as free-ranging and the use of drugs is reduced or absent, may prove beneficial to biodiversity by fostering the occurrence of spatial heterogeneity, and increasing the availability of trophic resources to wildlife. Previous work indicates that the presence of cattle in lowlands leads to an increase in bat foraging activity, yet no study has addressed this topic in mountainous regions, where free-ranging livestock is still common. Here we explore the relationships between landscape structure, farming and bat activity in a mountainous agricultural area, hypothesizing that bat activity will increase in response to the presence of livestock and landscape structure and heterogeneity. We found that traditional cattle farming may have a role in influencing bat activity in mountainous agroecosystems, yet its effects are evident for a limited number of species. Three pipistrelle species favoured foraging in areas subjected to cattle farming by hunting more often over cattle or fresh dung than at control sites. Free-ranging cattle thus provide profitable foraging opportunities for bats in mountainous landscapes, which remarks the importance of traditional farming activities in sustaining biodiversity. Cattle might also benefit from bat foraging activity if this leads to suppression of bloodsucking pests
Induction of annexin-1 during TRAIL-induced apoptosis in thyroid carcinoma cells
We investigated the expression of annexin-1 (ANXA1) in thyroid carcinoma cell lines and in thyroid cancers with a different degree of differentiation. The highest level of ANXA1 expression examined by Western blotting was detected in the papillary carcinoma cells (NPA) and in the follicular cells (WRO). On the other hand, the most undifferentiated thyroid carcinoma cells (ARO and FRO) presented the lowest level of ANXA1 expression. In surgical tissue specimens from 32 patients with thyroid cancers, we found high immunoreactivity for ANXA1 in papillary (PTC) and follicular (FTC) thyroid cancers while in undifferentiated thyroid cancers (UTC) the expression of the protein was barely detectable. Control thyroid tissue resulted positive for ANXA1. In summary, 70% of UTC examined weakly expressed ANXA1, whereas 65% of PTC or FTC specimens tested showed high expression of the protein. Thus ANXA1 expression may correlate with the tumorigenesis suggesting that the protein may represent an effective differentiation marker in thyroid cancer
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