853 research outputs found
Validation of the Lower Tagus Valley velocity and structural model using ambient noise broadband measurements
Along his history the Lower Tagus Valley (LTV) region was shaken by several earthquakes, some of them were
produced in large ruptures of offshore structures located southwest of the Portuguese coastline, among these we
the Lisbon earthquake of 1 November 1755; other moderates earthquakes were produced by local sources such as
the 1344, 1531 and the 1909 Benavente earthquake.
In order to promote an improved assessment of the seismic hazard in this region, we propose the introduction
of realistic methods on the prediction of ground motion produced by moderate to large earthquakes in LTV.
This process involves the establishment of a structural 3D model based on all the available geophysical and
geotechnical data on the area (seismic, gravimetric, deep wells and geological outcrops) and the determination of
wave propagation from a finite difference method: by applying the E3D program [1,2].
To confirm this model we use broadband ambient noise measurements collected in two profiles with azimuth
perpendicular to the basin axis and we applied the horizontal to vertical (H/V) spectral ratio method [3] to the
recordings in order to estimate the amplification of the basin. The H/V curves obtained reveals the existence of two
low frequency peaks centered on 0.2 a 1 Hz frequencies[4]. These peaks are strongly related with the thickness
of Cenozoic and alluvial sediments. By inversion of the H/V curve, we obtain a more detailed velocity model for
the region where the profile were determined, which is in good agreement with borehole data and other results
obtained with magnetic and seismic reflection methods
Periovulatory Hormonal Profiles after Estrus Induction and Conception Rate by Fixed-Time AI in Payoya Goats during the Anestrous Season
Sexual activity in domestic goats is positively influenced by reducing the photoperiod. Various protocols have therefore been developed in goats for the induction and synchronization of estrus during those months in which their sexual activity is reduced. The present observational study evaluates the periovulatory hormonal profile in Payoya goats (n = 24), during a non-favorable photoperiod (i.e., spring), being treated for estrus induction. The treatment comprised the vaginal insertion of sponges impregnated with progestogen (fluorogestone acetate, FGA), together with cloprostenol and equine chorionic gonadotrophin (eCG), 48 h before the end of the treatment. When the treatment ended, the plasma concentrations of the LH, FSH, progesterone and estradiol were determined. The goats were inseminated 46 h after the sponge withdrawal, and a pregnancy diagnosis was carried out 40–45 days after the insemination. Various parameters were monitored, such as the peaks of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and estradiol, and their respective intervals, in reference to the time of the sponge withdrawal. The conception rate was 62.5%, and the kidding rate was 50%. The results record the hormonal release pattern after the estrus synchronization treatment based on the FGA, and the differences between the pregnant and non-pregnant goats. The findings suggest that the LH peak produced after the estrus synchronization treatment, both in terms of the amplitude and the time of increment, is involved in the reproductive failure detected
Somatotypes trajectories during adulthood and their association with COPD phenotypes
Rationale: Chronic obstructive pulmonary disease (COPD) comprises distinct phenotypes, all characterised by airflow limitation.
Objectives: We hypothesised that somatotype changes - as a surrogate of adiposity - from early adulthood follow different trajectories to reach distinct phenotypes.
Methods: Using the validated Stunkard''s Pictogram, 356 COPD patients chose the somatotype that best reflects their current body build and those at ages 18, 30, 40 and 50 years. An unbiased group-based trajectory modelling was used to determine somatotype trajectories. We then compared the current COPD-related clinical and phenotypic characteristics of subjects belonging to each trajectory.
Measurements and main results: At 18 years of age, 88% of the participants described having a lean or medium somatotype (estimated body mass index (BMI) between 19 and 23 kg.m(-2)) while the other 12% a heavier somatotype (estimated BMI between 25 and 27 kg.m(-2)). From age 18 onwards, five distinct trajectories were observed. Four of them demonstrating a continuous increase in adiposity throughout adulthood with the exception of one, where the initial increase was followed by loss of adiposity after age 40. Patients with this trajectory were primarily females with low BMI and D-LCO (diffusing capacity of the lung for carbon monoxide). A persistently lean trajectory was seen in 14% of the cohort. This group had significantly lower forced expiratory volume in 1 s (FEV1), D-LCO, more emphysema and a worse BODE (BMI, airflow obstruction, dyspnoea and exercise capacity) score thus resembling the multiple organ loss of tissue (MOLT) phenotype.
Conclusions: COPD patients have distinct somatotype trajectories throughout adulthood. Those with the MOLT phenotype maintain a lean trajectory throughout life. Smoking subjects with this lean phenotype in early adulthood deserve particular attention as they seem to develop more severe COPD
Necessary Optimality Conditions for Higher-Order Infinite Horizon Variational Problems on Time Scales
We obtain Euler-Lagrange and transversality optimality conditions for
higher-order infinite horizon variational problems on a time scale. The new
necessary optimality conditions improve the classical results both in the
continuous and discrete settings: our results seem new and interesting even in
the particular cases when the time scale is the set of real numbers or the set
of integers.Comment: This is a preprint of a paper whose final and definite form will
appear in Journal of Optimization Theory and Applications (JOTA). Paper
submitted 17-Nov-2011; revised 24-March-2012 and 10-April-2012; accepted for
publication 15-April-201
Transversality Conditions for Infinite Horizon Variational Problems on Time Scales
We consider problems of the calculus of variations on unbounded time scales.
We prove the validity of the Euler-Lagrange equation on time scales for
infinite horizon problems, and a new transversality condition.Comment: Submitted 6-October-2009; Accepted 19-March-2010 in revised form; for
publication in "Optimization Letters"
Contrasting Heat Stress Response Patterns of Coral Holobionts Across the Red Sea Suggest Distinct Mechanisms of Thermal Tolerance
Corals from the northern Red Sea, in particular the Gulf of Aqaba (GoA), have exceptionally high bleaching thresholds approaching \u3e5℃ above their maximum monthly mean (MMM) temperatures. These elevated thresholds are thought to be due to historical selection, as corals passed through the warmer Southern Red Sea during recolonization from the Arabian Sea. To test this hypothesis, we determined thermal tolerance thresholds of GoA versus central Red Sea (CRS) Stylophora pistillata corals using multi-temperature acute thermal stress assays to determine thermal thresholds. Relative thermal thresholds of GoA and CRS corals were indeed similar and exceptionally high (~7℃ above MMM). However, absolute thermal thresholds of CRS corals were on average 3℃ above those of GoA corals. To explore the molecular underpinnings, we determined gene expression and microbiome response of the coral holobiont. Transcriptomic responses differed markedly, with a strong response to the thermal stress in GoA corals and their symbiotic algae versus a remarkably muted response in CRS colonies. Concomitant to this, coral and algal genes showed temperature-induced expression in GoA corals, while exhibiting fixed high expression (front-loading) in CRS corals. Bacterial community composition of GoA corals changed dramatically under heat stress, whereas CRS corals displayed stable assemblages. We interpret the response of GoA corals as that of a resilient population approaching a tipping point in contrast to a pattern of consistently elevated thermal resistance in CRS corals that cannot further attune. Such response differences suggest distinct thermal tolerance mechanisms that may affect the response of coral populations to ocean warming
Density functional method for nonequilibrium electron transport
We describe an ab initio method for calculating the electronic structure,
electronic transport, and forces acting on the atoms, for atomic scale systems
connected to semi-infinite electrodes and with an applied voltage bias. Our
method is based on the density functional theory (DFT) as implemented in the
well tested Siesta approach (which uses non-local norm-conserving
pseudopotentials to describe the effect of the core electrons, and linear
combination of finite-range numerical atomic orbitals to describe the valence
states). We fully deal with the atomistic structure of the whole system,
treating both the contact and the electrodes on the same footing. The effect of
the finite bias (including selfconsistency and the solution of the
electrostatic problem) is taken into account using nonequilibrium Green's
functions. We relate the nonequilibrium Green's function expressions to the
more transparent scheme involving the scattering states. As an illustration,
the method is applied to three systems where we are able to compare our results
to earlier ab initio DFT calculations or experiments, and we point out
differences between this method and existing schemes. The systems considered
are: (1) single atom carbon wires connected to aluminum electrodes with
extended or finite cross section, (2) single atom gold wires, and finally (3)
large carbon nanotube systems with point defects.Comment: 18 pages, 23 figure
Probing quantum gravity using photons from a flare of the active galactic nucleus Markarian 501 observed by the MAGIC telescope
We analyze the timing of photons observed by the MAGIC telescope during a
flare of the active galactic nucleus Mkn 501 for a possible correlation with
energy, as suggested by some models of quantum gravity (QG), which predict a
vacuum refractive index \simeq 1 + (E/M_{QGn})^n, n = 1,2. Parametrizing the
delay between gamma-rays of different energies as \Delta t =\pm\tau_l E or
\Delta t =\pm\tau_q E^2, we find \tau_l=(0.030\pm0.012) s/GeV at the 2.5-sigma
level, and \tau_q=(3.71\pm2.57)x10^{-6} s/GeV^2, respectively. We use these
results to establish lower limits M_{QG1} > 0.21x10^{18} GeV and M_{QG2} >
0.26x10^{11} GeV at the 95% C.L. Monte Carlo studies confirm the MAGIC
sensitivity to propagation effects at these levels. Thermal plasma effects in
the source are negligible, but we cannot exclude the importance of some other
source effect.Comment: 12 pages, 3 figures, Phys. Lett. B, reflects published versio
Unfolding of differential energy spectra in the MAGIC experiment
The paper describes the different methods, used in the MAGIC experiment, to
unfold experimental energy distributions of cosmic ray particles (gamma-rays).
Questions and problems related to the unfolding are discussed. Various
procedures are proposed which can help to make the unfolding robust and
reliable. The different methods and procedures are implemented in the MAGIC
software and are used in most of the analyses.Comment: Submitted to NIM
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