2,029 research outputs found
Mecanismos focales en el sur de España: periodo 1965-1985
Focal mechanism of 95 earthquakes for the period 1965-1985 with magnitud between 3.5 and 5.5 in south of Spain are studied. Fault-plane solutions for 16 individual events have been calculated [13 correspond to shallow earthquake (h < 30 km) and 3 to events with intermediate depth (30 < h < 150 km)]. Of the solutions, 6 correspond to normal faults, 4 to inverse faults and 3 to strike-slip faults. loint solutions have been calculated for 7 groups of earthquakes. They correspond, 5 to normal faults and 2 to inverse faults. The results have been correlated with the main geological faults in the area.En este trabajo, se presentan los mecanismos focales de terremotos ocurridos en el período 1965-1985 en el sur de España. Se han seleccionado 95 terremotos, cuya magnitud oscila entre 3,5 y 5,5. De ellos se han calculado el mecanismo focal individual de 16 terremotos, 13 corresponden a terremotos superficiales (h < 30 km) y 3 a terremotos de profundidad intermedia (30 < h < 150 km). De las soluciones obtenidas, 6 corresponden a fallas normales, 4 indican movimientos de fallas inversas, y 3 corresponden a fallas de desgarre. Se han calculado 7 soluciones conjuntas de grupos de terremotos, constituidos todos ellos por sismos superficiales. De estos mecanismos conjuntos, se han obtenido 5 soluciones que corresponden a falla normal y 2 a fallas inversas. Los resultados se correlacionan con las principales fracturas de la región, con el fin de interpretarlos desde el punto de vista sismotectónico
Four New Delta Scuti Pulsators from a Variability Survey of 131 Stars
In a photometric variability survey of 131 stars with B < 14 mag, we have
found four new Delta Scuti stars. We were sensitive to oscillation amplitudes
as low as a few mmag. The detection rate of short-period (P < 0.1 d) pulsating
variable stars, which may be relevant for planned large variability surveys
such as GAIA, POI, and even the LSST, was therefore 3%. All four new variable
stars have low pulsation amplitude (tens of mmag), and one has a very short
period (0.0198 d). This star is one of the fastest known Delta Scuti pulsators.
The short period of this variable star makes it observationally tractable, and
it may therefore be a particularly good candidate for asteroseismological
studies. All four new variable stars will add to the cadre of low-amplitude and
relatively short-period Delta Scuti stars that are potentially useful for
learning about the structure of stars on or near the main sequence, slightly
more massive than the Sun.Comment: To appear in the June 2002 issue of PASP, 9 pages, 6 figure
Coastal altimetry products in the strait of Gibraltar
This paper analyzes the availability and accuracy of coastal altimetry sea
level products in the Strait of Gibraltar. All possible repeats of two sections
of the Envisat and AltiKa ground-tracks were used in the eastern and western
portions of the strait. For Envisat, along-track sea level anomalies (SLAs) at
18-Hz posting rate were computed using ranges from two sources, namely, the
official SGDRs and the outputs of a coastal waveform retracker, the ALES
retracker; in addition, SLAs at 1 Hz were obtained from CTOH, France. For
AltiKa, along-track SLA at 40 Hz was also computed both from SGDR and ALES
ranges. The quality of these altimeter products was validated using two tide
gauges located on the southern coast of Spain. We observed an improvement of
about 20% in the accuracy of the Envisat SLAs from ALES compared to the
standard (SGDR) and the reprocessed CTOH data sets. AltiKa shows higher
accuracy, with no significant differences between SGDR and ALES
Use-wear and residue analysis of pounding tools used by wild capuchin monkeys (Sapajus libidinosus) from Serra da Capivara (Piauí, Brazil)
Bearded capuchin monkeys (Sapajus libidinosus) from Serra da Capivara National Park (Brazil), perform the widest range of activities using stone tools of all the non-human tool-using primates. The behaviours behind this range of tool-use have been closely documented, but little is known about the characteristics of the tools themselves. Here we redress this imbalance and adopt an archaeological perspective to the analysis of capuchin pounding tools. We apply, for the first time, systematic microscopic techniques to the analysis of capuchin stone tools used for digging, cracking cashew nuts and seed processing to characterise their damage patterns combined with residue spatial distribution and micro-remains analysis. This work presents a standardized methodology for future primate archaeological use-wear studies as well as forming a reference collection which can be used to identify different activities within the primate archaeological record. Furthermore, understanding the archaeologically visible traces of primate percussive behaviours represents an initial step in developing a methodology to investigate if similar activities were practiced by early hominins and to help identify these activities in the Plio-Pleistocene archaeological record
Origin of slow magnetic relaxation in Kramers ions with non-uniaxial anisotropy
Transition metal ions with long-lived spin states represent minimum size magnetic bits. Magnetic memory has often been associated with the combination of high spin and strong uniaxial magnetic anisotropy. Yet, slow magnetic relaxation has also been observed in some Kramers ions with dominant easy-plane magnetic anisotropy, albeit only under an external magnetic field. Here we study the spin dynamics of cobalt(II) ions in a model molecular complex. We show, by means of quantitative first-principles calculations, that the slow relaxation in this and other similar systems is a general consequence of time-reversal symmetry that hinders direct spin–phonon processes regardless of the sign of the magnetic anisotropy. Its magnetic field dependence is a subtle manifestation of electronuclear spin entanglement, which opens relaxation channels that would otherwise be forbidden but, at the same time, masks the relaxation phenomenon at zero field. These results provide a promising strategy to synthesize atom-size magnetic memories
Acute renal failure in an AIDS patient on tenofovir: a case report
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens
Data production models for the CDF experiment
The data production for the CDF experiment is conducted on a large Linux PC
farm designed to meet the needs of data collection at a maximum rate of 40
MByte/sec. We present two data production models that exploits advances in
computing and communication technology. The first production farm is a
centralized system that has achieved a stable data processing rate of
approximately 2 TByte per day. The recently upgraded farm is migrated to the
SAM (Sequential Access to data via Metadata) data handling system. The software
and hardware of the CDF production farms has been successful in providing large
computing and data throughput capacity to the experiment.Comment: 8 pages, 9 figures; presented at HPC Asia2005, Beijing, China, Nov 30
- Dec 3, 200
Data processing model for the CDF experiment
The data processing model for the CDF experiment is described. Data
processing reconstructs events from parallel data streams taken with different
combinations of physics event triggers and further splits the events into
datasets of specialized physics datasets. The design of the processing control
system faces strict requirements on bookkeeping records, which trace the status
of data files and event contents during processing and storage. The computing
architecture was updated to meet the mass data flow of the Run II data
collection, recently upgraded to a maximum rate of 40 MByte/sec. The data
processing facility consists of a large cluster of Linux computers with data
movement managed by the CDF data handling system to a multi-petaByte Enstore
tape library. The latest processing cycle has achieved a stable speed of 35
MByte/sec (3 TByte/day). It can be readily scaled by increasing CPU and
data-handling capacity as required.Comment: 12 pages, 10 figures, submitted to IEEE-TN
Asteroseismology with the WIRE satellite. I. Combining Ground- and Space-based Photometry of the Delta Scuti Star Epsilon Cephei
We have analysed ground-based multi-colour Stromgren photometry and
single-filter photometry from the star tracker on the WIRE satellite of the
delta scuti star Epsilon Cephei. The ground-based data set consists of 16
nights of data collected over 164 days, while the satellite data are nearly
continuous coverage of the star during 14 days. The spectral window and noise
level of the satellite data are superior to the ground-based data and this data
set is used to locate the frequencies. However, we can use the ground-based
data to improve the accuracy of the frequencies due to the much longer time
baseline. We detect 26 oscillation frequencies in the WIRE data set, but only
some of these can be seen clearly in the ground-based data. We have used the
multi-colour ground-based photometry to determine amplitude and phase
differences in the Stromgren b-y colour and the y filter in an attempt to
identify the radial degree of the oscillation frequencies. We conclude that the
accuracies of the amplitudes and phases are not sufficient to constrain
theoretical models of Epsilon Cephei. We find no evidence for rotational
splitting or the large separation among the frequencies detected in the WIRE
data set. To be able to identify oscillation frequencies in delta scuti stars
with the method we have applied, it is crucial to obtain more complete coverage
from multi-site campaigns with a long time baseline and in multiple filters.
This is important when planning photometric and spectroscopic ground-based
support for future satellite missions like COROT and KEPLER.Comment: 13 pages, 12 figures, 4 tables. Fig. 4 reduced in quality. Accepted
by A&
Partitioning of trace elements in a entrained flow IGCC plant: Influence of selected operational conditions
The partitioning of trace elements and the influence of the feed conditions (50:50 coal/pet-coke feed blend and limestone addition) was investigated in this study. To this end feed fuel, fly ash and slag samples were collected under different operational conditions at the 335 MW Puertollano IGCC power plant (Spain) and subsequently analysed. The partitioning of elements in this IGCC plant may be summarised as follows: (a) high volatile elements (70–>99% in gas phase): Hg, Br, I, Cl and S; (b) moderately volatile elements (up to 40% in gas phase and 60% in fly ash): As, Sb, Se, B, F, Cd, Tl, Zn and Sn; (c) elements with high condensation potential: (>90% in fly ash): Pb, Ge, Ga and Bi; (d) elements enriched similarly in fly ash and slag 30–60% in fly ash: Cu, W, (P), Mo, Ni and Na; and (e) low volatile elements (>70% in slag): Cs, Rb, Co, K, Cr, V, Nb, Be, Hf, Ta, Fe, U, Ti, Al, Si, Y, Sr, Th, Zr, Mg, Ba, Mn, REEs, Ca and Li. The volatility of As, Sb, and Tl and the slagging of S, B, Cl, Cd and low volatile elements are highly influenced by the fuel geochemistry and limestone dosages, respectively
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