312 research outputs found
Evaluación del dispositivo Pavement Quality Indicator (PQI) en la determinación de la densidad in situ de mezclas fabricadas con emulsión bituminosa
The Pavement Quality Indicator (PQI) is a non-nuclear gauge used for the on-site density measurement of asphalt pavements without the need to extract core samples. Previous studies of hot asphalt mixes found that PQI density readings were very similar to laboratory density measurements of pavement cores. This paper describes the first stage of a research project whose objective is to analyze PQI density measurements of mixes manufactured with an asphalt emulsion binder. The PQI density variability for such mixes was verified and compared with the results obtained with other on-site methods for measuring pavement density.El equipo Pavement Quality Indicator es un dispositivo para la determinación de densidad in situ en pavimentos asfálticos sin extracción de testigos. Las experiencias con este equipo en mezclas bituminosas en caliente, recogidas en diferentes fuentes bibliográficas, muestran que las densidades medidas in situ con el PQI son muy similares a las obtenidas mediante la extracción de testigos. En este artículo se expone la primera etapa de un proyecto de investigación que tiene por objeto analizar los resultados de mediciones efectuadas con PQI en mezclas bituminosas donde se utiliza emulsión asfáltica como ligante. Se comprueba la variabilidad de la densidad obtenida con el equipo para este tipo de mezclas, y se comparan los resultados con otros métodos de medida de densidad in situ
Variability of early autumn planktonic assemblages in the strait of Gibraltar: a regionalization analysis
The Strait of Gibraltar (SG) is the only connection of the Mediterranean Sea with the global circulation. The SG is an outstanding
marine region to explore physical-biological coupling of pelagic communities due to its hydrodynamic complexity, including strong
tidal forcing and marked spatial gradients and fronts. The authors have unravelled the role of the fortnightly tidal scale (spring and
neap tides) and local processes (upwelling and tidal-topographic mixing) that shape planktonic assemblages in the Strait. To do so,
an oceanographic cruise was taken in early autumn 2008 with a high-resolution grid sampling and spring/neap tidal conditions. The
planktonic features were captured using different automatic and semi-automatic techniques of plankton analyses (flow cytometry,
FlowCAM, LOPC and Ecotaxa) that allowed covering a wide range of sizes of the community from pico- to mesoplankton. The SG
was sectorized into two clusters based on the biogeochemical and main water column properties. Cluster 1 (CL1) covered shallow
productive areas around Cape Trafalgar (CT). CL1 presented higher concentrations of chlorophyll and nutrients, and phytoplankton
was mostly represented by Synechococcus and coastal diatoms while zooplankton had the highest percentage of meroplankton (31%).
In contrast, cluster 2 (CL2) covered open ocean waters and presented more oligotrophic features, i.e. nitrogen-depleted waters with
lower chlorophyll concentrations and a picoplankton community dominated by Prochlorococcus and holoplankton predominance in
mesozooplankton. Under early autumn conditions with overall nutrient-depleted and stratified waters, the CT area emerges as an ecosystem
where the constant tidal mixing and nutrients supply is coupled with an active production also being favored by high residence
times and finally shaping a plankton community with unique features in the area.En prensa0,56
The Expanding Nebular Remnant of the Recurrent Nova RS Ophiuchi (2006): II. Modeling of Combined Hubble Space Telescope Imaging and Ground-based Spectroscopy
We report Hubble Space Telescope imaging, obtained 155 and 449 days after the
2006 outburst of the recurrent nova RS Ophiuchi, together with ground-based
spectroscopic observations, obtained from the Observatorio Astron\'omico
Nacional en San Pedro M\'artir, Baja California, M\'exico and at the
Observatorio Astrof\'isico Guillermo Haro, at Cananea, Sonora, M\'exico. The
observations at the first epoch were used as inputs to model the geometry and
kinematic structure of the evolving RS Oph nebular remnant. We find that the
modeled remnant comprises two distinct co-aligned bipolar components; a
low-velocity, high-density innermost (hour glass) region and a more extended,
high-velocity (dumbbell) structure. This overall structure is in agreement with
that deduced from radio observations and optical interferometry at earlier
epochs. We find that the asymmetry observed in the west lobe is an instrumental
effect caused by the profile of the HST filter and hence demonstrate that this
lobe is approaching the observer. We then conclude that the system has an
inclination to the line of sight of 39 degrees. This is in
agreement with the inclination of the binary orbit and lends support to the
proposal that this morphology is due to the interaction of the outburst ejecta
with either an accretion disk around the central white dwarf and/or a
pre-existing red giant wind that is significantly denser in the equatorial
regions of the binary than at the poles. The second epoch HST observation was
also modeled. However, as no spectra were taken at this epoch, it is more
difficult to constrain any model. Nevertheless, we demonstrate that between the
two HST epochs the outer dumbbell structure seems to have expanded linearly.Comment: 33 pages, 9 figures, 1 table, accepted for publication in Ap
Cyclic brightening in the short-period WZ Sge-type cataclysmic variable SDSS J080434.20+510349.2
We have observed a new cataclysmic variable (CV) SDSS J080434.20+510349.2 and
study the origin of a long-term variability found in its light curve.
Multi-longitude time-resolved photometric observations were carried out to
analyze the uncommon behavior also found recently in two newly discovered CVs.
This study of SDSS J080434.20+510349.2 mainly concerns the understanding of the
nature of the observed double-humped light curve and its relation to a cyclic
brightening occurring during quiescence. The observations were obtained early
in 2007, when the object was at about V~17.1, 0.4 mag brighter than the
pre-outburst magnitude. The light curve shows a sinusoidal variability with an
amplitude of about 0.07 mag and a periodicity of 42.48 min, which is half of
the orbital period of the system. In addition, we have observed two
"mini-outbursts" of the system up to 0.6 mag, with a duration of about 4 days
each. The "mini-outburst" had a symmetric profile and repeated in about 32
days. Subsequent monitoring of the system shows a cyclical behaviour of such
"mini-outbursts" with a similar recurrence period. The origin of the
double-humped light curve and the periodic brightening is discussed in the
light of the evolutionary state of SDSS J080434.20+510349.2.Comment: 7 pages, 6 figures, Accepted by A&A, typos added, figure correcte
Long-term benefits of nevirapine-containing regimens: multicenter study with 506 patients, followed-up a median of 9 years
[Abstract] OBJECTIVE: To evaluate long-term outcomes in patients maintaining a nevirapine (NVP)-based regimen.
METHODS: Retrospective, multicenter, cohort study including patients currently receiving an NVP regimen that had been started at least 5 years previously. Demographic, clinical, and analytical variables were recorded.
RESULTS: Median follow-up was 8.9 (5.7-11.3) years. Baseline characteristics: 74% men, 47 years old, 36% drug users, 40% AIDS, 40% HCV+, 51.4% detectable HIV-1 viral load, CD4 count 395 (4-1,421)/μL, 19% CD4 3.37 mmol/L significantly decreased in a subsample with available values. A significant decrease in transaminases, alkaline phosphatase, and Fib4 score was observed, mainly in HCV+ and ARV-naive patients.
CONCLUSIONS: In patients who tolerate NVP therapy, (even those with HCV coinfection), long term benefits may be significant in terms of a progressive improvement in general health status markers and CD4 response, a favorable lipid profile, and good liver tolerability
Astroclimate at San Pedro M\'artir I: 2004-2008 Seeing Statistics from the TMT Site Testing Data
We present comprehensive seeing statistics for the San Pedro M\'artir site
derived from the Thirty Meter Telescope site selection data. The observations
were obtained between 2004 and 2008 with a Differential Image Motion Monitor
(DIMM) and a Multi Aperture Scintillation Sensor (MASS) combined instrument
(MASS--DIMM). The parameters that are statistically analised here are: whole
atmosphere seeing -measured by the DIMM-; free atmosphere seeing --measured by
the MASS--; and ground-layer seeing (GL) --difference between the total and
free-atmosphere seeing--. We made a careful data coverage study along with
statistical distributions of simultaneous MASS--DIMM seeing measurements, in
order to investigate the nightly, monthly, seasonal, annual and global
behaviour, as well as possible hourly seeing trends. Although this campaign
covers five years, the sampling is uneven, being 2006 and 2007 the best sampled
years in terms of seasonal coverage. The overall results yield a median seeing
of 0.78 (DIMM), 0.37 (MASS) and 0.59 arcsec (GL). The strongest contribution to
the whole atmosphere seeing comes, therefore, from a strong ground layer. We
find that the best season is summer, while the worst one is winter, in
accordance with previous studies. It is worth noting that the best yearly
results are correlated with the best sampled years. The hourly analysis shows
that there is no statistically significant tendency of seeing degradation
towards dawn. The seeing values are slightly larger than those reported before.
This may be caused by climate changes.Comment: Accepted for publication (2012 June 14) in MNRAS, 15 pages, 16
Figures, 8 Table
Molecular epidemiology of enterovirus 71, coxsackievirus A16 and A6 associated with hand, foot and mouth disease in Spain
Producción CientíficaHand, foot and mouth disease (HFMD) is a childhood illness frequently caused by genotypes belonging to the enterovirus A species,
including coxsackievirus (CV)-A16 and enterovirus (EV)-71. Between 2010 and 2012, several outbreaks and sporadic cases of HFMD
occurred in different regions of Spain. The objective of the present study was to describe the enterovirus epidemiology associated with
HFMD in the country. A total of 80 patients with HFMD or atypical rash were included. Detection and typing of the enteroviruses were
performed directly in clinical samples using molecular methods. Enteroviruses were detected in 53 of the patients (66%). CV-A6 was the
most frequent genotype, followed by CV-A16 and EV-71, but other minority types were also identified. Interestingly, during almost all of
2010, CV-A16 was the only causative agent of HFMD but by the end of the year and during 2011, CV-A6 became predominant, while
CV-A16 was not detected. In 2012, however, both CV-A6 and CV-A16 circulated. EV-71 was associated with HFMD symptoms only in
three cases during 2012. All Spanish CV-A6 sequences segregated into one major genetic cluster together with other European and Asian
strains isolated between 2008 and 2011, most forming a particular clade. Spanish EV-71 strains belonged to subgenogroup C2, as did most of
the European sequences circulated. In conclusion, the recent increase of HFMD cases in Spain and other European countries has been due
to a larger incidence of circulating species A enteroviruses, mainly CV-A6 and CV-A16, and the emergence of new genetic variants of these
viruses
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