85 research outputs found
Pulsating hot O subdwarfs in ω Centauri: mapping a unique instability strip on the extreme horizontal branch
No full textpeer reviewedWe present the results of an extensive survey for rapid pulsators among Extreme Horizontal Branch (EHB) stars in ω Cen. The observations performed consist of nearly 100 h of time-series photometry for several off-centre fields of the cluster, as well as low-resolution spectroscopy for a partially overlapping sample. We obtained photometry for some 300 EHB stars, for around half of which we are able to recover light curves of sufficient quality to either detect or place meaningful non-detection limits for rapid pulsations. Based on the spectroscopy, we derive reliable values of log g, T[SUB]eff[/SUB] and log N(He) /N(H) for 38 targets, as well as good estimates of the effective temperature for another nine targets, whose spectra are slightly polluted by a close neighbour in the image. The survey uncovered a total of five rapid variables with multi-periodic oscillations between 85 and 125 s. Spectroscopically, they form a homogeneous group of hydrogen-rich subdwarf O stars clustered between 48 000 and 54 000 K. For each of the variables we are able to measure between two and three significant pulsations believed to constitute independent harmonic oscillations. However, the interpretation of the Fourier spectra is not straightforward due to significant fine structure attributed to strong amplitude variations. In addition to the rapid variables, we found an EHB star with an apparently periodic luminosity variation of ~2700 s, which we tentatively suggest may be caused by ellipsoidal variations in a close binary. Using the overlapping photometry and spectroscopy sample we are able to map an empirical ω Cen instability strip in log g - T[SUB]eff[/SUB] space. This can be directly compared to the pulsation driving predicted from the Montréal "second-generation" models regularly used to interpret the pulsations in hot B subdwarfs. Extending the parameter range of these models to higher temperatures, we find that the region where p-mode excitation occurs is in fact bifurcated, and the well-known instability strip between 29 000-36 000 K where the rapid subdwarf B pulsators are found is complemented by a second one above 50 000 K in the models. While significant challenges remain at the quantitative level, we believe that the same κ-mechanism that drives the pulsations in hot B subdwarfs is also responsible for the excitation of the rapid oscillations observed in the ω Cen variables. Intriguingly, the ω Cen variables appear to form a unique class. No direct counterparts have so far been found either in the Galactic field, nor in other globular clusters, despite dedicated searches. Conversely, our survey revealed no ω Cen representatives of the rapidly pulsating hot B subdwarfs found among the field population, though their presence cannot be excluded from the limited sample. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile (proposal IDs 083.D-0833, 386.D-0669, 087.D-0216 and 091.D-0791).The reduced spectra are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/589/A1</A
Efectividad del cipionato de estradiol inyectado al final de un tratamiento con progesterona sobre la eficiencia reproductiva
No full textEl cipionato de estradiol (CPE) ha sido utilizado para reemplazar al benzoato de estradiol (BE) administrado vía IM 24 h después de retirado el dispositivo intravaginal con progesterona (DISP), sin afectar los porcentajes de preñez. El objetivo del trabajo fue evaluar el efecto de dos dosis de CPE inyectado al retirar un DISP, sobre el porcentaje de preñez post inseminación artificial a tiempo fijo (IATF). Como objetivo secundario, se planteó comparar la eficiencia reproductiva de los tratamientos utilizados. Se emplearon 79 vaquillonas de 15 meses de edad. El día 0, se les colocó un DISP más BE. El día 7 se retiró el DISP, se administró D(+) cloprostenol y en forma aleatoria se inyectó 0,5 mg de CPE, 1 mg de CPE o BE 24 h después. Para la IATF (52–56 h) se utilizó semen proveniente de un toro de probada fertilidad. El día 22 se colocó a todas las vaquillonas un DISP de segundo uso, retirándolo 7 días después. Se continuó con detección de celo e IA. El diagnóstico de gestación se realizó por ultrasonografía en dos oportunidades para evaluar preñez de IATF y retorno, así como para verificar mortalidad embrionaria. Se evaluó el efecto de los tratamientos sobre la preñez a la IATF, del retorno y final. No se observaron efectos del tratamiento (p>0,05) sobre los porcentajes de preñez a la IATF (51,9%), del retorno (61,1%) y final (65,8%). Se observó un 7,3% de pérdidas embrionarias (p>0,05). Se concluye que la administración de 0,5 o 1 mg de CPE al retirar un DISP con progesterona en lugar de BE a las 24 h posteriores es igualmente efectiva para implementar una IATF. Además, no resulta afectada la eficiencia reproductiva del rodeo.
In Memoriam : Dr. Carlos Raúl Sanz (10/11/1942 - 16/3/2019)
No full textResumen: Tras recibir los santos sacramentos y rodeado del cariño de su esposa,
doña María Angélica Chayer y de sus hijos y nietos, recientemente hubo que
lamentar el fallecimiento del doctor Carlos Raúl Sanz, ocurrido en la ciudad
de Buenos Aires, el 16 de marzo de 2019 –fiesta de San Gabriel Brochero,
cuya vida y obra difundiera. Sus restos descansan en Vela (Tandil, provincia
de Buenos Aires).
Nacido el 10 de noviembre de 1942 en San Andrés de Giles (provincia
de Buenos Aires), donde se educó, cursó luego sus estudios universitarios
en la Facultad de Derecho de la Pontificia Universidad Católica Argentina
“Santa María de los Buenos Aires”, en la que se graduó como abogado con
diploma de honor. Complementó su formación en la Facultad de Filosofía
de esa misma casa de estudios, con la guía de Mons. Guillermo P. Blanco.
También en Lenguas Clásicas, Política y Economía.
Ayudante del P. Domingo Basso, O.P. en la Cátedra de Teología Moral
en la Facultad de Filosofía y Letras –Escuela de Pedagogía y Psicopedagogía–,
de la Universidad en que se graduara, también tuvo a su cargo la
Cátedra de Filosofía Social. En la Carrera de Historia de la misma Facultad,
fue Profesor Titular de la asignatura Elementos de Derecho y Economía..
Efecto de diferentes ésteres de estradiol utilizados para sincronizar la ovulación sobre el porcentaje de preñez a la IATF en vacas Angus
No full textThe estradiol cypionate (ECP) allows animals inseminated at fixed time (FTAI) performing three enclosures. Recently there have been varying results, therefore, the objective of this work was to evaluate the use of ECP administered at device removal upon pregnancy rate after FTAI. Two trials were conducted (E1 and E2), using 273 lactating beef cows. On day 0 cows received a progesterone intravaginal device plus EB. On day 8, the intravaginal device was removed, cows received a luteolytic dose of PGF and were randomized to receive either ECP at 0 h or EB at 24 h. On day 10, 50-53 h after device removal, fixed-time artificial insemination was performed using frozen/thawed semen of proven fertility bulls (EI: GS y SE; EII: M y ME) and two inseminators. Pregnancy diagnosis was performed on day 40 by ultrasonografy. Pregnancy rates were not different between treatments (ECP: 55,17%; EB:58,59 %), inseminators (T: 54,79%; A: 59,06%) and bull (E1: GS: 55,3% y SE: 60,0%; E2: M:51,5% y SE: 59,1%). Interactions were not significant (P>0,05). In conclusion, according to our finding, estradiol cypionate could be used instead of estradiol benzoate to synchronize ovulation without affecting the pregnancy rate at fixed timed artificial insemination.El Cipionato de estradiol (CPE) permite inseminar animales a tiempo fijo (IATF) realizando tres encierres. Recientemente han surgido resultados variables, por lo tanto, el objetivo del presente trabajo fue evaluar el uso del CPE administrado al retirar un dispositivo intravaginal sobre el porcentaje de preñez a la IATF. Se realizaron 2 ensayos (EI y EII), utilizando 273 vacas con cría. El día 0 se colocó un dispositivo más BE. El día 8 se retiró el dispositivo, se administró prostaglandina, y los animales recibieron aleatoriamente, CPE en ese momento o BE 24 h posteriores. El día 10, 50-53 h post retiro, se realizó IATF utilizando semen de toros de probada fertilidad (EI: GS y SE; EII: M y ME) y dos inseminadores. El día 40 se realizó diagnóstico de gestación mediante ultrasonografía. No se observaron efectos del tratamiento (CPE: 55,17%; BE: 58,59%), inseminador (T: 54,79%; A: 59,06%), toro (E1: GS:55,3% y SE: 60,0%; E2: M: 51,5% y SE: 59,1%) y de sus interacciones sobre el porcentaje de preñez (P>0,05). Se concluye que en las condiciones del presente trabajo se puede utilizar CPE al retirar un dispositivo en lugar de BE a las 24 h sin afectar el porcentaje de preñez
JWST Fine Guidance Sensor Calibration
No full textAbstract. The primary function of the Fine Guidance Sensor (FGS) is to provide continuous pointing information to the Observatory. The FGS will image two separate regions of the JWST field of view onto two independent 2k x 2k infrared focal planes arrays, which will cover a wavelength range of 0.6 to 5 µm. Once in fine guiding, the FGS will provide continuous pointing information to a precision of ≤ 5 milli-arc seconds at an update rate of 16 Hz for J 18.5 magnitude stars. In order to fulfill its functions, i.e., Identification, Acquisition, Track, and Fine Guide, the FGS will require calibration. In this paper, we present a brief overview of the FGS design, its operations, and its calibration
Estimation of aortic valve effective orifice area by Doppler echocardiography : effects of valve inflow shape and flow rate
No full textBACKGROUND:
The effective orifice area (EOA) is the standard parameter for the clinical assessment of aortic stenosis severity. It has been reported that EOA measured by Doppler echocardiography does not necessarily provide an accurate estimate of the cross-sectional area of the flow jet at the vena contracta, especially at low flow rates. The objective of this study was to test the validity of the Doppler-derived EOA.
METHODS:
Triangular and circular orifice plates, funnels, and bioprosthetic valves were inserted into an in vitro aortic flow model and were studied under different physiologic flow rates corresponding to cardiac outputs varying from 1.5 to 7 L/min. For each experiment, the EOA was measured by Doppler and compared with the catheter-derived EOA and with the EOA derived from a theoretic formula. In bioprostheses, the geometric orifice area (GOA) was estimated from images acquired by high-speed video recording.
RESULTS:
There was no significant difference between the EOA derived from the 3 methods with the rigid orifices (Doppler vs catheter: y = 0.97x +0.18 mm(2), r(2) = 0.98; Doppler vs theory: y = 1.00x -3.60 mm(2), r(2) = 0.99). Doppler EOA was not significantly influenced by the flow rate in rigid orifices. As predicted by theory, the average contraction coefficient (EOA/GOA) was around 0.6 in the orifice plates and around 1.0 in the funnels. In the bioprosthetic valves, both EOA and GOA increased with increasing flow rate whereas contraction coefficient was almost constant with an average value of 0.99. There was also a very good concordance between EOA and GOA (y = 0.94x +0.05 mm(2), r(2) = 0.88).
CONCLUSIONS:
In rigid aortic stenosis, the Doppler EOA is much less flow dependent than generally assumed. Indeed, it depends mainly on the GOA and the inflow shape (flat vs funnel-shaped) of the stenosis. The flow dependence of Doppler EOA observed in clinical studies is likely a result of a variation of the valve GOA or of the valve inflow shape and not an inherent flow dependence of the EOA derived by the continuity equatio
0157: Echo-based diastolic intraventricular pressure difference as a surrogate of left ventricular untwisting
No full textBackgroundLeft ventricular (LV) early diastolic filling is related to an active process of LV relaxation, caused by its rapid untwisting. The untwisting rate (UR) has been reported to be a robust marker of diastolic function but is technically hard to assess in practice. The untwisting phenomenon generates a diastolic intraventricular pressure gradient (IVPGd), which can be assessed by colour Doppler M-Mode. Previous studies showed a close temporal relation between the UR and the IVPGd peaks, but the relation between their magnitudes as well as their load dependency remain unclear.MethodWe developed our own Matlab software for IVPGd assessment by colour Doppler M-Mode based on Bernoulli equation.From our research database, we retrieved all echocardiograms where ejection fraction was normal, the colour M-Mode tracing was available and UR was measurable using speckle tracking. Passive leg raising was used in 19 healthy volunteers to study the impact of preload on the IVPGd measurement.ResultsWe included 104 echocardiograms (83% males, median age 23y [19-69]). The median peak IVPGd was 3.1mmHg [1.6-7.8] and correlated to the peak UR (r=0.57, P<0.0001, figure). There was also a significant correlation between the IVGPd peak and E’ (r=0.62, P<0.0001). For peak IVPGd, correlations between inter- and intra-observer measures were calculated on 10 randomly selected subjects and were 0.83 and 0.99 (P<0.05). Compared to UR and E’, IVPGd was also significantly increased with leg lifting (2.7±0.8mmHg vs 3.3±0.8mmHg, P<0.001).ConclusionPeak IVPGd based on colour Doppler M mode echocardiography is positively correlated to the LV UR. Despite the observation that IVPGd is not less load-dependent than other parameters, it requires only an echo loop easily obtained during routine clinical studies and is highly reproducible using a semi-automatic software algorithm. This new tool could easily become a new practical echo index for diastolic function assessment.Abstract 0157 - Figur
Structural parameters of the hot pulsating B subdwarf PG 1219+534 from asteroseismology
No full textOver the last several years, we have embarked on a long term effort to exploit the strong potential that hot B subdwarf (sdB) pulsators have to offer in terms of asteroseismology. This effort is multifaceted as it involves, on the observational front, the acquisition of high sensitivity photometric data supplemented by accurate spectroscopic measurements, and, on the theoretical and modeling fronts, the development of appropriate numerical tools dedicated to the asteroseismological interpretation of the seismic observations. In this paper, we report on the observations and thorough analysis of the rapidly pulsating sdB star (or EC 14026 star) PG 1219+534. Our model atmosphere analysis of the time averaged optical spectrum of PG 1219+534 obtained at the new Multiple Mirror Telescope (MMT) leads to estimates of T{eff}= 33 600 ± 370 K and log g=5.810 ± 0.046 (with log N(He)/N(H)=-1.49 ± 0.08), in good agreement with previous spectroscopic measurements of its atmospheric parameters. This places PG 1219+534 right in the middle of the EC 14026 instability region in the log g-Teff plane. A standard Fourier analysis of our high signal-to-noise ratio Canada-France-Hawaii Telescope (CFHT) light curves reveals the presence of nine distinct harmonic oscillations with periods in the range 122{-}172 s, a significant improvement over the original detection of only four periods by Koen et al. (1999, MNRAS, 305, 28). On this basis, we have carried out a detailed asteroseismic analysis of PG 1219+534 using the well-known forward method and assuming that the observed modes have ℓ&leq 3. Our analysis leads objectively to the identification of the (k, ℓ) indices of the nine periods observed in the star PG 1219+534, and to the determination of its structural parameters. The periods all correspond to low-order acoustic modes with adjacent values of k and with ℓ=0, 1, 2, and 3. They define a band of unstable modes, in close agreement with nonadiabatic pulsation theory. Furthermore, the average dispersion between the nine observed periods and the periods of the corresponding nine theoretical modes of the optimal model is only 0.6%, comparable to the results of a similar analysis carried out by Brassard et al. (2001) on the rapid sdB pulsator PG 0014+067. On the basis of our combined spectroscopic and asteroseismic analysis, the inferred global structural parameters of PG 1219+534 are Teff= 33 600 ± 370 K, log g=5.8071 ± 0.0057, log Menv/M*=-4.254 ± 0.147, M*=0.457 ± 0.012 M⊙, R/R⊙=0.1397 ± 0.0028, and L/L⊙=22.01 ± 1.85. Combined with detailed model atmosphere calculations, we estimate, in addition, that this star has an absolute visual magnitude M_V=4.62 ± 0.06 and is located at a distance d=531 ± 23 pc (using V=13.24 ± 0.20). Finally, if we interpret the absence of fine structure (frequency multiplets) as indicative of a slow rotation rate of that star, we further find that PG 1219+534 rotates with a period longer than 3.4 days, and has a maximum rotational broadening velocity of V sin i 2.1 km s-1
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