A 10 años de su visita. Cousteau y la Calypso en Cuba.

Artículo realizado para recordar la visita hace 10 años a Cuba de Jacques Ives Cousteau. Se identifican los resultados más relevantes a la luz del tiempo transcurrido y su significación.

Ricardo Bastida, su arte y los peces.

Esta serie tiene como propósito mostrar diferentes expresiones artísticas relacionadas con la Ictiología nacional y regional, generadas en diferentes épocas y que surgen por diversas motivaciones personales que, en algún caso, muestran casi con exactitud a los modelos que inspiraron la obra, en otras, por lo contrario, responden a la imaginación y creatividad del autor. En este caso nos referimos a la prolífica obra de Ricardo Bastida, destacado biólogo nacional e internacional y un artista marplatense con un estilo muy marcado y personal. Sólo me resta invitar a quienes quieran sumarse a esta iniciativa, se acerquen con sus aportes para consolidar esta idea, ya que podría ser otro instrumento de difusión del conocimiento de nuestra disciplina a los diferentes estamentos de la sociedad.

Y-chromosome evidence of southern origin of the East Asian - Specific haplogroup O3-M122

The prehistoric peopling of East Asia by modern humans remains controversial with respect to early population migrations. Here, we present a systematic sampling and genetic screening of an East Asian-specific Y-chromosome haplogroup (O3-M122) in 2,332 individuals from diverse East Asian populations. Our results indicate that the O3-M122 lineage is dominant in East Asian populations, with an average frequency of 44.3%. The microsatellite data show that the O3-M122 haplotypes in southern East Asia are more diverse than those in northern East Asia, suggesting a southern origin of the O3-M122 mutation. It was estimated that the early northward migration of the O3-M122 lineages in East Asia occurred similar to 25,000-30,000 years ago, consistent with the fossil records of modern humans in East Asia.

An observation of performances in carp-prawn polyculture in respect of fingerlings size and water area

Performances of fingerling size and water area was studied. Seven species of fish included 25% of Hypophthalmichthys molitrix, 15% of Gada catla, 20% of Labeo rohita, 10% of Cirrhinus mrigala, 10% of Ctenophyringodon idella and 20% of Macrobrachium rosenbergii were stocked at the rate of 8,000 individual/ha along Barbodes gonionoms at 6.0g weight size with a stocking density of 2,000 indl./ ha. Survival of all species was in the range of 39.9 to 96.3% except M. rosenbergii The highest survival was obtained from L. rohita (96.3%) followed by C mrigala (96.0 %)., B. gonionotus (92.3%), C idella (90.6%), H. molitrix (84.0%), C cada (81.7%) respectively. While the survival of M. rosenbergiiwas 13.1%. The highest production of 4912 kg/ha/yr was obtained from the bigger ponds (0.4 ha) stocked with 20-32g size of fingerlings, while lowest production (3123 kg/ha/yr) from small pond (0.1 ha) stocked with 3-10 g fingerlings. Economic analysis shows the highest net profit in bigger ponds stocked with bigger fish seed.

La reproducción de la merluza en el Mar Argentino (Merlucciidae, Meluccius merluccius hubbsi) : 2. La reproducción de la merluza y su relación con otros aspectos biológicos de la especie

The paper deals with the spawning cycle of the hake, Merluccius merluccius hubbsi in the fishing area of the Argentine fleet, SW Atlantic (35°- 46° L. S.: 53°- 63° L.W.; 30-160 fathoms depth). It was made on the basis of the weekly sampling of the commercial catch in the period January 1965 - March 1968. The results have been compared with those of the exploratory surveys made by the United Nations Fisheries Development Program (República Argentina - FAO). The histological study, which was made with 741 specimens, was most intensive in females than in males. The results have been compared with the sexual stage determinations of both sexes in the total samples during the period before mentioned. The conclusions are: 1. The analysis of the ovocytes frequency distributions showed a period of resting or slow recuperation (April - August) with a mode of 120 ~k and one of rapid transformation (October - December) from 120 μ tíll 830 ~k. After December it appears again the mode of 120 ~k which indicated the reserve stock. 2. The maturity factor shows in both sexes a period of low values , 0,52 to 2% (April - September) and, another with higher values (October - March). In the first period the values are concentrated, while in the second one a large dispersion is observed produced by the rapidity of the growth process of the gonads. It is more evident between November and December. 3. The liver weight variations, compared with the degree of ingestion and the values of the maturity factor, in time, demonstrated that: a) after two periods of abundant ingestion (March - April and October- November) there are two increases of the liver index; b) the increase of the Iiver index has a direct relation to the maturity factor; c) at the end of the summer season, when the values of the maturity factor decrease, those of the liver index are still high. This demonstrates that the hake does not arrive exhausted at the end of the spawning season and that a rapid recuperation for a new spawning by part of the stock is possible. 4. Females predominate in the samples during most of the year. In the period October - December, when sexual activation occurs, as it is demonstrated by the high values of the maturity factor, proportions are nearly 1 :1, and males at times are more numerous than females. 5. The analisys of the advaneed maturity stages, in relation to total length shows that in the hake, Iike in other fishes, the largest ones mature first. This applies for both sexes. 6. The study of the maturity factor values and the sexual stages of the samples allows the recognition of two spawning periods, the main one in summer (October - March) and another in winter (June - July). 7. Part of the summer spawners, with a rapid recuperation, should be able to spawn again in winter. This indicates that the hake population, acording to our samples, has two different possibilities of spawning. 8. After analysis of the frequency percentages composition of mature specimens it is concluded that during the summer season, when hake is fished in shallow waters and in a wide area (38°– 43° L.S.) the fleet is fishing on the spawning stocks. Some winter spawners specimens have been found at 37°- 38° L.S. and in waters of more than 100 fathoms depth. 9. A new maturity scale of seven stages is proposed, instead of the one of six stages now in use. The new added stage corresponds to the postspawners during its resting period.

Robust airfoil design with respect to boundary layer transition

In order to disign an airfoil of which maximum lift coefficient (CL max) is not sensitive to location of forced top boundary layer transition. Taking maximizing mean value of CL max and minimizing standard deviation as biobjective, leading edge radius, manximum thickness and its location, maximum camber and its location as deterministic design variables, location of forced top boundary layer transition as stochastic variable, XFOIL as deterministic CFD solver, non-intrusive polynomial chaos as substitute of Monte Carlo method, we completed a robust airfoil design problem. Results demonstrate performance of initial airfoil is enhanced through reducing standard deviation of CL max. Besides, we also know maximum thickness has the most dominating effect on mean value of CL max, location of maximum thickness has the most dominating effect on standard deviation of CL max, maximum camber has a little effect on both mean value and standard deviation, and maximum camber is the only element of which increase can lead increase of mean value and standard deviation at the same time. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc.

Direct detection of the relative strength of Rashba and Dresselhaus spin-orbit interaction: Utilizing the SU(2) symmetry

We propose a simple method to detect the relative strength of Rashba and Dresselhaus spin-orbit interactions in quantum wells (QWs) without relying on the directional-dependent physical quantities. This method utilizes the two different critical gate voltages that leading to the remarkable signals of SU(2) symmetry, which happens to reflect the intrinsic-structure-inversion asymmetry of the QW. We support our proposal by the numerical calculation of in-plane relaxation times based on the self-consistent eight-band Kane model. We find that the two different critical gate voltages leading to the maximum spin-relaxation times [one effect of the SU(2) symmetry] can simply determine the ratio of the coefficients of Rashba and Dresselhaus terms. Our proposal can also be generalized to extract the relative strengths of the spin-orbit interactions in quantum-wire and quantum-dot structures.

A lattice dynamical treatment for the total potential energy of single-walled carbon nanotubes and its applications: relaxed equilibrium structure, elastic properties, and vibrational modes of ultra-narrow tubes

In this paper, we propose a lattice dynamic treatment for the total potential energy of single-walled carbon nanotubes (SWCNTs) which is, apart from a parameter for the nonlinear effects, extracted from the vibrational energy of the planar graphene sheet. The energetics, elasticity and lattice dynamics are treated in terms of the same set of force constants, independently of the tube structures. Based upon this proposal, we have investigated systematically the relaxed lattice configuration for narrow SWCNTs, the strain energy, the Young's modulus and Poisson ratio, and the lattice vibrational properties with respect to the relaxed equilibrium tubule structure. Our calculated results for various physical quantities are nicely in consistency with existing experimental measurements. In particular, we verified that the relaxation effect makes the bond length longer and the frequencies of various optical vibrational modes softer. Our calculation provides evidence that the Young's modulus of an armchair tube exceeds that of the planar graphene sheet, and that the large diameter limits of the Young's modulus and Poisson ratio are in agreement with the experimental values of graphite; the calculated radial breathing modes for ultra-narrow tubes with diameters ranging between 2 and 5 angstrom coincide with the experimental results and the existing ab initio calculations with satisfaction. For narrow tubes with a diameter of 20 angstrom, the calculated frequencies of optical modes in the tubule's tangential plane, as well as those of radial breathing modes, are also in good agreement with the experimental measurements. In addition, our calculation shows that various physical quantities of relaxed SWCNTs can actually be expanded in terms of the chiral angle defined for the corresponding ideal SWCNTs.

SU(2)Chern-Simons涡旋解的拓扑结构

运用规范势分解理论研究了Dunne-Jackiw-Pi-Trugenberger模型中的自对偶方程,得到一个静态的自对偶Chern-Simons多涡旋解,每个涡旋由5个参数描述。发现了自对偶解与拓扑数之间的关系,而拓扑数由Brouwer度与Hopf指标确定。同时,也研究了该涡旋解的磁通量的拓扑量子化。

SU(2)规范场分解与Bose-Einstein凝聚体中的环流条件

利用SU(2)规范场的单位矢量场分解形式讨论了Bose-Einstein凝聚体中的环流条件.对于二分量Bose-Einstein凝聚,内部态的SU(2)对称性将导致一个拓扑环流条件,这是一个推广的Mer-min—Ho关系.