979 resultados para Data portal
Resumo:
We have surveyed the frequency band 218.30-263.55 GHz toward the core positions N and M and the quiescent cloud position NW in the Sgr B2 molecular cloud using the Swedish-ESO Submillimetre Telescope. In total 1730, 660, and 110 lines were detected in N, M, and NW, respectively, and 42 different molecular species were identified. The number of unidentified lines are 337, 51, and eight. Toward the N source, spectral line emission constitutes 22% of the total detected flux in the observed band, and complex organic molecules are the main contributors. Toward M, 14% of the broadband flux is caused by lines, and SO2 is here the dominant source of emission. NW is relatively poor in spectral lines and continuum. In this paper we present the spectra together with tables of suggested line identifications.
Resumo:
A 330--360 GHz spectral survey of the hot molecular core associated with the 'cometary' ultracompact HII region G 34.3+/-0.15 observed with the James Clerk Maxwell Telescope has detected 338 spectral lines from at least 35 distinct chemical species plus 19 isotopomers. 70 lines remain unidentified. Chemical abundance and rotation temperature have been determined by rotation diagram analysis for 12 species, and lower limits to abundance found for 38 others.
Resumo:
We propose an exchange rate model that is a hybrid of the conventional specification with monetary fundamentals and the Evans–Lyons microstructure approach. We estimate a model augmented with order flow variables, using a unique data set: almost 100 monthly observations on interdealer order flow on dollar/euro and dollar/yen. The augmented macroeconomic, or “hybrid,” model exhibits greater in-sample stability and out of sample forecasting improvement vis-à-vis the basic macroeconomic and random walk specifications.
Resumo:
We present the results of trawling through the SuperWASP data base for classical and recurrent novae. We report light curves for a nova in eruption, and for classical novae and a recurrent nova in quiescence. For five objects in quiescence, we report periodicity, arising in most cases from orbital modulation of the light from the cool secondary star. The stability of the SuperWASP system means that these data have huge potential for the study not only of novae in eruption, but also of the long-term modulations of light during quiescence.
Resumo:
Multicore computational accelerators such as GPUs are now commodity components for highperformance computing at scale. While such accelerators have been studied in some detail as stand-alone computational engines, their integration in large-scale distributed systems raises new challenges and trade-offs. In this paper, we present an exploration of resource management alternatives for building asymmetric accelerator-based distributed systems. We present these alternatives in the context of a capabilities-aware framework for data-intensive computing, which uses an enhanced implementation of the MapReduce programming model for accelerator-based clusters, compared to the state of the art. The framework can transparently utilize heterogeneous accelerators for deriving high performance with low programming effort. Our work is the first to compare heterogeneous types of accelerators, GPUs and a Cell processors, in the same environment and the first to explore the trade-offs between compute-efficient and control-efficient accelerators on data-intensive systems. Our investigation shows that our framework scales well with the number of different compute nodes. Furthermore, it runs simultaneously on two different types of accelerators, successfully adapts to the resource capabilities, and performs 26.9% better on average than a static execution approach.