Simulación mediante ordenador de movimientos bidimensionales en medios resistentes

We have accomplished a simulation program of mechanics; it is developed in laboratory practice by students in their first years of physics studies ata University level. Its aim is a better understanding of the influence of the variable forces of friction in bidimensional movements. We have verified the effectiveness of this teaching method through the evaluation of the students' progress during the courses in which we have carried out this practice

Effect of litter separation on 24-hour rhythmicity of plasma prolactin, follicle-stimulating hormone and luteinizing hormone levels in lactating rabbit does

BACKGROUND: This work describes the effect of a 48-h litter separation on 24-h patterns of plasma prolactin, FSH and LH concentration in female lactating rabbits kept under a 16:8 light-dark photoperiod (lights on at 0800 h). METHODS: Groups of 6–7 female lactating rabbits maintained with their litters or separated from them for 48 h were killed by decapitation on day 11 post-partum, at 6 different time points throughout a 24-h cycle, starting at 0900 h. Plasma levels of prolactin, FSH and LH were measured by specific double antibody radio-immunoassays. RESULTS: Plasma level of prolactin in control and separated does changed in a similar way throughout the day, showing two maxima, at 0500–0900 h and at 1700–2100 h, respectively. Litter separation significantly augmented plasma FSH and LH and disrupted their 24-h rhythmicity. CONCLUSION: Since previous studies had shown that litter separation for short periods of time augmented sexual receptivity and fertility of the doe, the changes in FSH and LH reported may influence the massive release of gonadotropin releasing hormone, LH and FSH triggered by mating or artificial insemination in litter-separated mothers

Effect of rabbit doe-litter separation on 24-hour changes of luteinizing hormone, follicle stimulating hormone and prolactin release in female and male suckling pups

BACKGROUND: The daily pattern of nursing of the rabbit pup by the doe is the most important event in the day for the newborn and is neatly anticipated by them. Such anticipation presumably needs a close correlation with changes in hormones that will allow the pups to develop an appropriate behavior. Although a number of circadian functions have been examined in newborn rabbits, there is no information on 24-h pattern of gonadotropin release or on possible sex-related differences in gonadotropin or prolactin (PRL) release of pups. This study examined the 24-h changes of plasma luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) in 11 days old suckling female and male rabbits left with the mother or after short-term (i.e., 48 h) doe-litter separation. METHODS: Animals were kept under controlled light-dark cycles (16 h – 8 h; lights on at 08:00 h). On day 9 post partum, groups of 6–7 female or male rabbit pups were separated from their mothers starting at 6 different time intervals in the 24 h cycle. Pups were killed 48 h after separation. At each time interval groups of male or female pups that stayed with the mother were killed as controls. Plasma, LH, FSH and PRL levels were measured by specific radioimmunoassays. RESULTS: In pups kept with their mother plasma FSH and LH maxima occurred at the first and second part of the light phase (at 13:00 and 17:00 – 21:00 h, respectively) (females) or as two peaks for each of the hormones (at 13:00 and 01:00 h) (males). PRL release was similar in female and male rabbit pups kept with their mother, showing a 24-h pattern with two peaks, at 13:00 and 01:00 h, respectively. Mean 24-h values of gonadotropins and PRL did not differ between sexes. Isolation of pups for 48 h augmented circulating gonadotropin and PRL levels and distorted hormone 24-h pattern to a similar extent in both sexes. CONCLUSION: Significant sex differences in 24-h changes in LH and FSH, but not in PRL, release occurred in rabbit pups kept with the doe. Separation of newborn pups from their mother augmented circulating gonadotropin and PRL levels and disrupted 24-h rhythmicity of gonadotropin and PRL release similarly in both sexes. The effect of pups' isolation can be attributed either to a modification of the circadian pacemaker or to a masking effect on some of its output overt rhythms

Studies on age determination and growth pattern of the wedge sole Dicologoglossa cuneata (Moreau, 1881) in the Spanish waters of the Gulf of Cadiz (southwest Iberian Peninsula)

The wedge sole Dicologoglossa cuneata (Moreau, 1881) is a typical coastal soleid which is considered as one of the main target species in the demersal fishery of Spain's southern Atlantic region. This paper presents a study on the growth pattern of wedge sole in the Gulf of Cadiz. Age was determined by observing and analysing whole otoliths (sagittae), thereby obtaining the mean lengths at age for males and females in the year 1993 (from 15-20.9 cm TL and 1-4 years for males; from 15.9-23.6 cm TL and 1-6 years for females). In addition, the growth parameters for both sexes were obtained according to the Von Bertalanffy equation: L∞ = 24 cm, K = 0.343 and t0 = -1.384 for males; L∞ = 27 cm, K = 0.296 and t0 = -1.520 for females (showing growth differences growth between the sexes). These were compared with results reported by other authors for other areas of the species's distribution range. Through the interpretation of the otolith and its edge, a sequence of annual rapid- and slow-growth rings was observed; otoliths with an opaque edge (rapid growth) showed the highest percentages in the period from May to October. Mean otolith diameters for each of the estimated ages were calculated, as well as the body length/otolith diameter relationship: a = -12.631 and b = 61.033 (r² = 0.70).La acedía Dicologoglossa cuneata (Moreau, 1881) es un soleido típicamente costero, considerado como una de las especies objetivo de las pesquerías demersales de la región suratlántica ibérica. En este trabajo se estudia el patrón de crecimiento de la acedía del golfo de Cádiz. La determinación de la edad se realizó mediante la lectura de otolitos enteros (sagitta), obteniéndose las tallas medias por clase de edad para machos y hembras del año 1993 (entre 15 y 20,9 cm de longitud total y de 1 a 4 años para machos; de 15,9 a 23,6 cm de longitud total y de 1 a 6 años para hembras). Por otra parte, se estimaron los parámetros de crecimiento para ambos sexos según la ecuación de Von Bertalanffy: L∞ = 24 cm, K = 0,343 y t0 = -1,384 para machos; L∞ = 27 cm, K = 0,296 y t0 = -1,520 para hembras, presentando ambos sexos un crecimiento diferente. Estos resultados se compararon con los obtenidos por otros autores en otras áreas del rango de distribución de la especie. Mediante la interpretación del otolito y su borde, se observa una sucesión anual de anillos de crecimiento lento, formados durante el periodo invernal, y otros de crecimiento rápido, que muestran los porcentajes más altos en el periodo de mayo a octubre. Se calcularon los diámetros de los anillos para cada una de las edades estimadas, así como la relación longitud total del pez - diámetro del otolito, obteniéndose una ecuación lineal en la que a = -12,631 y b = 61,033 (r² = 0,70).Instituto Español de Oceanografí

Evaluación del área trabecular por digitalización de imágenes en el callo de fractura: estudio experimental

Se presenta un método de evaluación del área trabecular por medio de digitalización de imágenes de microscopía óptica. Se estudia la evolución de 20 callos de fractura en ratas de cepa Wistar, obteniendo un incremento progresivo del área trabecular desde los 14 a los 49 días, correlacionando ésta directamente con la actividad neoformativa. Se concluye proponiendo el uso de este método por su uniformidad, objetividad y reproductibilidad en todo el estudio, permitiendo la independencia del anatomopatológico.We present a method for assessment of the bone trabecular area by using optic microscope digitalized imaging. We studied 20 fracture callus performed at the tibia in Wistar rats. The bone trabecular area had a progressive increased from 14 to 49 days, post-fracture, been directly related with the neoformative activity. We propose this method because of this uniformity, objetivity and reliability. This method akows fracture repair analysis independently of the subjetivity of the pathologist

Multiwavelength characterisation of an ACT-selected, lensed dusty star-forming galaxy at z=2.64

We present \ci\,(2--1) and multi-transition $^{12}$CO observations of a dusty star-forming galaxy, ACT\,J2029+0120, which we spectroscopically confirm to lie at $z$\,=\,2.64. We detect CO(3--2), CO(5--4), CO(7--6), CO(8--7), and \ci\,(2--1) at high significance, tentatively detect HCO$^{+}$(4--3), and place strong upper limits on the integrated strength of dense gas tracers (HCN(4--3) and CS(7--6)). Multi-transition CO observations and dense gas tracers can provide valuable constraints on the molecular gas content and excitation conditions in high-redshift galaxies. We therefore use this unique data set to construct a CO spectral line energy distribution (SLED) of the source, which is most consistent with that of a ULIRG/Seyfert or QSO host object in the taxonomy of the \textit{Herschel} Comprehensive ULIRG Emission Survey. We employ RADEX models to fit the peak of the CO SLED, inferring a temperature of T$\sim$117 K and $n_{\text{H}_2}\sim10^5$ cm$^{-3}$, most consistent with a ULIRG/QSO object and the presence of high density tracers. We also find that the velocity width of the \ci\ line is potentially larger than seen in all CO transitions for this object, and that the $L'_{\rm C\,I(2-1)}/L'_{\rm CO(3-2)}$ ratio is also larger than seen in other lensed and unlensed submillimeter galaxies and QSO hosts; if confirmed, this anomaly could be an effect of differential lensing of a shocked molecular outflow.Comment: Accepted for publication in Ap

Looking for blazars in a sample of unidentified high-energy emitting Fermi sources

Context. Based on their overwhelming dominance among associated Fermi γ-ray catalogue sources, it is expected that a large fraction of the unidentified Fermi objects are blazars. Through crossmatching between the positions of unidentified γ-ray sources from the First Fermi Catalog of γ-ray sources emitting above 10 GeV (1FHL) and the ROSAT and Swift/XRT catalogues of X-ray objects and between pointed XRT observations, a sample of 36 potential associations was found in previous works with less than 15 arcsec of positional offset. One-third of them have recently been classified; the remainder, though believed to belong to the blazar class, still lack spectroscopic classifications. Aims. We study the optical spectrum of the putative counterparts of these unidentified gamma-ray sources in order to find their redshifts and to determine their nature and main spectral characteristics. Methods. An observational campaign was carried out on the putative counterparts of 13 1FHL sources using medium-resolution optical spectroscopy from the Osservatorio Astronomico di Bologna in Loiano, Italy; the Telescopio Nazionale Galileo and the Nordic Optical Telescope, both in the Canary Islands, Spain; and the Observatorio Astronómico Nacional San Pedro Mártir in Baja California, Mexico. Results. We were able to classify 14 new objects based on their continuum shapes and spectral features. Conclusions. Twelve new blazars were found, along with one new quasar and one new narrow line Seyfert 1 (NLS1) to be potentially associated with the 1FHL sources of our sample. Redshifts or lower limits were obtained when possible alongside central black hole mass and luminosity estimates for the NLS1 and the quasar.Fil: Marchesini, Ezequiel Joaquín. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Masetti, Nicola. Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; ItaliaFil: Chavushyan, V.. Instituto Nacional de Astrofísica, Óptica y Electrónica; MéxicoFil: Cellone, Sergio Aldo. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Andruchow, Ileana. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Bassani, L.. Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; ItaliaFil: Bazzano, A.. Istituto di Astrofisica e Planetologia Spaziali; ItaliaFil: Jiménez-Bailón, E.. Universidad Nacional Autónoma de México; MéxicoFil: Landi, R.. Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; ItaliaFil: Malizia, A.. Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; ItaliaFil: Palazzi, E.. Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; ItaliaFil: Patiño Álvarez, V.. Instituto Nacional de Astrofísica, Óptica y Electrónica; MéxicoFil: Rodríguez Castillo, G. A.. Osservatorio Astronomico di Roma; ItaliaFil: Stephen, J. B.. Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna; ItaliaFil: Ubertini, P.. Istituto di Astrofisica e Planetologia Spaziali; Itali

The binary mass ratio in the black hole transient MAXI J1820+070

We present intermediate resolution spectroscopy of the optical counterpart to the black hole X-ray transient MAXI J1820+070 (=ASASSN-18ey) obtained with the OSIRIS spectrograph on the 10.4-m Gran Telescopio Canarias. The observations were performed with the source close to the quiescent state and before the onset of renewed activity in August 2019. We make use of these data and K-type dwarf templates taken with the same instrumental configuration to measure the projected rotational velocity of the donor star. We find $v_{rot} \sin i = 84 \pm 5$ km s$^{-1}$ ($1\!-\!\sigma$), which implies a donor to black-hole mass ratio $q = {M_2}/{M_1} = 0.072 \pm 0.012$ for the case of a tidally locked and Roche-lobe filling donor star. The derived dynamical masses for the stellar components are $M_1 = (5.95 \pm 0.22)\sin ^{-3}i$ $M_\odot$ and $M_2 = (0.43 \pm 0.08) \sin^{-3}i$ $M_\odot$. The use of $q$, combined with estimates of the accretion disk size at the time of the optical spectroscopy, allows us to revise our previous orbital inclination constraints to $66^{\circ} < i < 81^{\circ}$. These values lead to 95% confidence level limits on the masses of $5.73 <M_1(M_\odot) < 8.34$ and $0.28 < M_2(M_\odot) < 0.77$. Adopting instead the $63 \pm 3^{\circ}$ orientation angle of the radio jet as the binary inclination leads to $M_1 = 8.48^{+0.79}_{-0.72} M_\odot$ and $M_2 = 0.61^{+0.13}_{-0.12} M_\odot$ ($1\!-\!\sigma$).Comment: 8 pages, 2 figures. Accepted for publication in ApJ

Parámetros reproductivos en el ganado vacuno de raza retinta explotado en dehesa: edad al primer parto e intervalo entre partos

La mejora de los caracteres reproductivos es de vital importancia para maximizar esta rentabilidad de las explotaciones de vacuno de carne, especialmente en las razas explotadas en régimen extensivo, como es el caso de la raza Retinta. Dicho sistema supone condiciones adversas e incluso extremas para los animales, especialmente durante la fase de recría fase fundamental y a la que generalmente se presta escasa atención en estas explotaciones. El objetivo del presente trabaja fue, analizar la posible influencia de distintos factores, tanto ambientales como genéticos, sobre la edad al primer parto (EPP) y el intervalo entre partos (IPP). Para ello hemos contando con los registros reproductivos correspondientes al Núcleo de Control de Rendimientos de la Raza Retinta. Estos incluían 2.786 primeros partos y 11.197 intervalos entre partos, correspondientes a 3. 112 vacas. Según nuestros resultados la edad al primer parto del ganado vacuno de raza Retinta se ve afectada por los factores ganadería de nacimiento, campaña y época de nacimiento, y la interacción de los tres. Dentro de estos factores, el factor ganadería absorbió del 52 al 66% de la variabilidad de la edad al primer parto. Otro factor que resulto significativo fue el tipo de alimentación que recibe la ternera durante el periodo predestete. Así mismo nuestros resultados muestras que dentro del rango de EPP estudiadas, no existe influencia sobre las condiciones de crecimiento del ternero de ese primer parto ni de los posteriores, incluso las novillas que paren a edad temprana (dentro de unos límites fisiológicos), produjeron más terneros y más pesados durante su vida. En cuanto al periodo medio entre partos encontramos una fuerte relación con la ganadería, y con el efecto campaña ganadera, correspondiendo los intervalos más largos a aquellos años en los que aparece un notable período de sequía. Independientemente a este factor, se aprecia una evidente disminución del IPP en la última década. El valor medio obtenido está fuertemente influenciado por el sistema de cubrición seguido (paridera restringida o continua). Según nuestros resultados las ganaderías con temporada de cubrición continua presentan menores intervalos, aunque con bajas diferencias, lo cual puede ser refleja de un manejo reproductivo menos optimizado que las de paridera estacional