4,565 research outputs found
The extremely asymmetric radio structure of the z=3.1 radio galaxy B3 J2330+3927
We report on 1.7 and 5.0 GHz observations of the z=3.087 radio galaxy B3
J2330+3927, using the Very Long Baseline Array (VLBA), and archival 1.4 and 8.4
GHz Very Large Array (VLA) data. Our VLBA data identify a compact, flat
spectrum (\alpha_{1.7 GHz}^{5 GHz} = -0.2 +/- 0.1; S_\nu ~ \nu^\alpha) radio
component as the core. The VLA images show that the fraction of core emission
is very large (f_c \approx 0.5 at 8.4 GHz), and reveal a previously undetected,
very faint counterjet, implying a radio lobe flux density ratio R >= 11 and a
radio lobe distance ratio Q \approx 1.9. Those values are much more common in
quasars than in radio galaxies, but the optical/near-IR spectra show a clear
type II AGN for B3 J2330+3927, confirming that it is indeed a radio galaxy.
Unlike all other radio galaxies, the bright Ly-\alpha emitting gas is located
towards the furthest radio arm. We argue against environmental and relativistic
beaming effects being the cause of the observed asymmetry, and suggest this
source has intrinsically asymmetric radio jets. If this is the case, B3
J2330+3927 is the first example of such a source at high redshift, and seems to
be difficult to reconcile with the unified model, which explains the
differences between quasars and radio galaxies as being due to orientation
effects.Comment: 6 pages, 3 figures, to appear as a Letter to MNRA
On the role of infiltration and exfiltration in swash zone boundary layer dynamics
Funded by Mexican National Council of Science and Technology (CoNACyT) . Grant Number: 490080 Fulbright-Garcia Robles grant Instituto de Ingeniería UNAM International Collaborative Research project University of Delaware DGAPA UNAM National Science Foundation . Grant Numbers: OCE-0845004 , OCE-1332703 University of Delaware UK Engineering and Physical Sciences Research Council ‘Flood MEMORY: Multi-Event Modelling Of Risk & recoverY’ . Grant Number: EP EP/K013513/1Peer reviewedPublisher PD
Absolute dimensions of the G7+K7 eclipsing binary star IM Virginis: Discrepancies with stellar evolution models
We report extensive spectroscopic and differential photometric BVRI
observations of the active, detached, 1.309-day double-lined eclipsing binary
IM Vir, composed of a G7-type primary and a K7 secondary. With these
observations we derive accurate absolute masses and radii of M(1) = 0.981 +/-
0.012 M(Sun), M(2) = 0.6644 +/- 0.0048 M(Sun), R(1) = 1.061 +/- 0.016 R(Sun),
and R(2) = 0.681 +/- 0.013 R(Sun) for the primary and secondary, with relative
errors under 2%. The effective temperatures are 5570 +/- 100 K and 4250 +/- 130
K. The significant difference in mass makes this a favorable case for
comparison with stellar evolution theory. We find that both stars are larger
than the models predict, by 3.7% for the primary and 7.5% for the secondary, as
well as cooler than expected, by 100 K and 150 K, respectively. These
discrepancies are in line with previously reported differences in low-mass
stars, and are believed to be caused by chromospheric activity, which is not
accounted for in current models. The effect is not confined to low-mass stars:
the rapidly-rotating primary of IM Vir joins the growing list of objects of
near-solar mass (but still with convective envelopes) that show similar
anomalies. The comparison with the models suggests an age of 2.4 Gyr for the
system, and a metallicity [Fe/H] of approximately -0.3 that is consistent with
other indications, but requires confirmation.Comment: 14 pages, 13 figures. Accepted for publication in Ap
Contractile Strength during Variable Heart Duration Is Species and Preload Dependent
We investigate the effect of beat-to-beat variability on cardiac contractility. Cardiac trabeculae were isolated from the right ventricle of rabbits and beagle dogs and stimulated to isometrically contract, alternating between fixed steady state versus variable interbeat intervals. Trabeculae were stimulated at physiologically relevant frequencies for each species (dog 1 and 4 Hz; rabbit 2 and 4 Hz) intercalating fixed periods with 40% variability. A subset of the trabeculae (at 90% of optimal length) was stretched prior to stimulation between 5 and 13% and stimulated at the same frequencies with a fixed versus 40% variation. Fixed rate response at the same base frequency was measured before and after each variable period and the average force reported. In canine preparations no change in force was observed as a result of the imposed variability in beat-to-beat duration. In the rabbit, we observed a nonsignificant decrease in force between fixed and variable pacing at both 2 and 4 Hz (n = 8) when 40% variability was introduced. When a 5% and 13% stretch was applied, the correlation coefficient sharply increased, indicating a more prominent impact of the prebeat duration on the following cycle with higher preload
Landslide Hazard in El Salvador
The destructive seismic events of January 13 (ML: 7.6) and February 13 (ML: 6.1) 2001 in El Salvador, with origin in the subduction area and the volcanic chain, respectively, provide an ideal scenario to analyse the factors that define the landslide hazard in this country. In this paper we analysed the events in terms of strong-motion and precedent climatic condition and their relation with the landslides induced; establishing a great opportunity to compare some hazard assessment methods as those proposed by Mora and Vahrson (1994) and Rodríguez (2001) which define the hazard in terms of the interaction between triggering agents and susceptibility conditions.
Historically both rainfalls and earthquakes have shown to be important triggers for landslides in El Salvador, and results show how the combination of these factors are also critical in defining trigger thresholds and in controlling failure mechanisms. It was found that the Mora and Vahrson method underestimates the landslides hazard; as was discussed by Bommer and Rodríguez (2002), this is mainly due to the rainfalls levels used by the method which were defined for the Costa Rica conditions, which are markedly different to those in El Salvador. The Rodríguez model describes in a better way the landslides hazard, however in some areas the hazard is overestimated due to the way as weighting factors for lithology shades the influence of topography, this suggests that assignment of weighting values in the model must be reviewed implementing a multivariate correspondence analysis instead of the bivariate model used so far
Consumer PHIM Going Beyond Paper and Computer Anxiety
Personal health information management (PHIM) refers to an individual’s use of various tools (i.e., email, paper, sticky notes, calendars, health portals) to manage their healthcare information (Jones 2008). With advances in technology, it becomes even more imperative that the healthcare community understand the factors that may influence consumers’ intentions to use various PHIM tools to manage his/her healthcare information. The Theory of Planned Behavior (TPB) and constructs from the Technology Acceptance Model (TAM), and the Computer Anxiety Rating Scale (CARS) guide this investigation into how consumers might use patient health portals to manage their healthcare information
A First Attempt into the Production of Acylglycerol Mixtures from Echium Oil
Enzymatic glycerolysis of Echium oil (Echium plantagineum) has been carried out in the presence of four commercial lipases. Different pretreatments of the reaction mixture, such as high pressure homogenization and addition of food grade monoolein as an emulsifier, were evaluated to test their influence on the glycerolysis reaction. In addition, the impact of reducing temperature and the utilization of a solvent generally recognized as safe as a flavoring agent, such as limonene, were also investigated. Conversion of ca. 60-70% of triacylglycerols and production of ca. 25-30% of monoacylglycerols (MAGs) were attained. Finally, at the best reaction conditions, the glycerolysis reaction was scaled up at pilot plant and the product mixture obtained was fractionated via molecular distillation. From this stage, two products were attained: a distillate containing 80% of MAGs and a residue containing approximately 50% of diacylglycerols and 50% of triacylglycerols. All these mixtures can be utilized as self-emulsifying vehicles for the formulation of bioactive substances and also as precursors for the production of structured bioactive lipidsThis work was supported by the Ministerio de Economía y Competitividad (INNSAOLI, project number IPT-2011-1248- 060000, subprograma INNPACTO) and the Comunidad de Madrid (ALIBIRD, project number S2013/ABI-2728
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