456 research outputs found
Genetic study of gestation length in andalusian and arabian mares
The length of gestation in Andalusian, or Spanish Purebred (SPB) and Arabian (AB) mares reared in Spain
was analysed, based on 766 spontaneous full-term deliveries appertaining to 141 mares of SPB breed and 72
mares of AB breed in 31 breeding seasons. The data were obtained from the Yeguada Militar de Jerez de la
Frontera stud farm in Cadiz, Spain. The mean length of gestation was of 336.8 ´ ± 0.48 days in the SPB mares
and 340.3 ± 0.63 days in AB mares. To assess the accurate prediction of time of birth the potential effect of
a number of factors was investigated. The influences of the breed, mare, month and year of mating, age of
the mother, number of births and sex of the foal were statistically significant. The factor have the greatest
influence over the gestation length was the mare itself, with a correlation among consecutive births of around
0.4. The effect of inbreeding, both of the mare and foal, was negligible. Gestation length shortened as the
breeding season progressed: in both breeds, a delay of 1 month in mating corresponded to a decrease of 3
days in the gestation length. According to our results, gestation length decrease as the mare gets older, with
the shortest gestation periods when the mare is 10–12 years old, and from this point on, it slowly increases.
The gestation period shortens as the 4th or 5th birth approaches, and then gets progressively longer. The
range of variation in gestation length due to the number of births to the mare is of 2.9 days for the AB mares,
and 2.2 days for SPB mares. The heritability for the gestation length for AB and the SPB breeds was 0.2, with
a repeatability of 0.36 and 0.37, for SPB and AB breeds, respectively. With the data from both breeds, and
using a classical approach, the response to selection was estimated if mares with extreme gestation lengths
were culled, i.e. lengths which are under 310 days, or over 360 days. According to our results, in the case of SPB, a decrease of 14–45% would occur in the number of extreme gestation lengths, while in the AB breed,
this value would decrease from 2 to 39%
Effects of periodic forcing in chaotic scattering
The effects of a periodic forcing on chaotic scattering are relevant in certain situations of physical interest. We investigate the effects of the forcing amplitude and the external frequency in both the survival probability of the particles in the scattering region and the exit basins associated to phase space. We have found an exponential decay law for the survival probability of the particles in the scattering region. A resonant-like behavior is uncovered where the critical values of the frequencies omega aprox. 1 and omega aprox. 2 permit the particles to escape faster than for other different values. On the other hand, the computation of the exit basins in phase space reveals the existence of Wada basins depending of the frequency values. We provide some heuristic arguments that are in good agreement with the numerical results. Our results are expected to be relevant for physical phenomena such as the effect of companion galaxies, among others
Carboxylic acid derivatives of tetrathiafulvalene: key intermediates for the synthesis of redox-active calixarene-based anion receptors
A series of calixarene–TTF (TTF=tetrathiafulvalene) receptors incorporating amide binding units for anion recognition have been synthesized and characterized. For this purpose, two synthetically versatile new TTF carboxylic acid derivatives were prepared and characterized by X-ray diffraction, these structures demonstrating the critical role of the carboxylic function in the solid-state organization. Some of the calixarene–amide–TTF assemblies exhibit strong binding of various anions, as shown by 1H NMR titration studies, and one receptor is able to electrochemically respond in the presence of H2PO4−, C6H5CO2− or CH3CO2− anion
Multiple myeloma primary cells show a highly rearranged unbalanced genome with amplifications and homozygous deletions irrespective of the presence of immunoglobulin-related chromosome translocations
Background and Objectives
Multiple myeloma (MM) is a malignant plasma cell neoplasia in which genetic studies
have shown that genomic changes may affect almost all chromosomes, as shown
by fluorescence in situ hybridization (FISH) and comparative genomic hybridization
(CGH). Our objective was the genomic characterization of CD 138 positive primary MM
samples by means of a high resolution array CGH platform.
Design and Methods
For the first time, a high resolution array CGH with more than 40,000 probes, has
been used to analyze 26 primary MM samples after the enrichment of CD138-positive
plasma cells.
Results
This approach identified copy number imbalances in all cases. Bioinformatics strategies
were optimized to perform data analysis allowing the segregation of hyperdiploid
and non-hyperdiploid cases by array CGH. Additional analysis showed that structural
chromosome rearrangements were more frequently seen in hyperdiploid cases. We
also identified the same Xq21 duplication in nearly 20% of the cases, which originated
through unbalanced chromosome translocations. High level amplifications and
homozygous deletions were recurrently observed in our series and involved genes
with meaningful function in cancer biology.
Interpretation and Conclusions
High resolution array CGH allowed us to identify copy number changes in 100% of the
primary MM samples. We segregated different MM subgroups based on their genomic
profiles which made it possible to identify homozygous deletions and amplifications
of great genetic relevance in MM
Exercise effects on erythrocyte deformability in exercise-induced arterial hypoxemia
Exercise-induced arterial hypoxemia (EIAH) is often found in endurance-trained subjects at high exercise intensity. The role of erythrocyte deformability (ED) in EIAH has been scarcely explored. We aimed to explore the role of erythrocyte properties and lactate accumulation in the response of ED in EIAH. ED was determined in 10 sedentary and in 16 trained subjects, both before and after a maximal incremental test, and after recovery, along with mean corpuscular volume (MCV) and red blood cell lactate concentrations. EIAH was found in 6 trained subjects ( 06SaO2=-8.25\ub14.03%). Sedentary and non-EIAH trained subjects showed reduced ED after exercise, while no effect on ED was found in EIAH trained subjects. After exercise, lactate concentrations rose and MCV increased equally in all groups. ED is strongly driven by cell volume, but the different ED response to exercise in EIAH shows that other cellular mechanisms may be implicated. Interactions between membrane and cytoskeleton, which have been found to be O2-regulated, play a role in ED. The drop in SaO2 in EIAH subjects can improve ED response to exercise. This can be an adaptive mechanism that enhances muscular and pulmonary perfusion, and allows the achievement of high exercise intensity in EIAH despite lower O2 arterial transport
Equilibria, periodic orbits around equilibria, and heteroclinic connections in the gravity field of a rotating homogeneous cube
This paper investigates the dynamics of a particle orbiting around a rotating
homogeneous cube, and shows fruitful results that have implications for
examining the dynamics of orbits around non-spherical celestial bodies. This
study can be considered as an extension of previous research work on the
dynamics of orbits around simple shaped bodies, including a straight segment, a
circular ring, an annulus disk, and simple planar plates with backgrounds in
celestial mechanics. In the synodic reference frame, the model of a rotating
cube is established, the equilibria are calculated, and their linear
stabilities are determined. Periodic orbits around the equilibria are computed
using the traditional differential correction method, and their stabilities are
determined by the eigenvalues of the monodromy matrix. The existence of
homoclinic and heteroclinic orbits connecting periodic orbits around the
equilibria is examined and proved numerically in order to understand the global
orbit structure of the system. This study contributes to the investigation of
irregular shaped celestial bodies that can be divided into a set of cubes.Comment: 29 pages, 16 figures, accepted for publication in Astrophysics &
Space Scienc
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