Quality of pejerrey (Odontesthes bonariensis) eggs and larvae in captivity throughout spawning season

The aim of this work was to assess the quality of pejerrey eggs and larvae throughout its spawning season. Fertilized eggs were taken on September, October, November, and December from a captive broodstock. The egg diameter, yolk diameter, and oil droplets area decreased along the spawning season, with higher values in September. Fertilization and hatching rates decreased throughout this period, with highest values in September (88.0%; 55.2%) and the lowest values on December (43.0%; 25.2%). The larvae hatched from eggs obtained on October were the heaviest and longest (1.57 mg; 8.24 mm). The survival rate at 30 days post hatching (dph) was similar in larvae from September and October eggs (66.1%; 62.9%) with a sharp decrease in larvae from November and December eggs (22.4%; 23.3%). Furthermore, the highest body weight (15.1 mg) and total length (15.25 mm) at 30 dph were obtained in larvae from October eggs. The results obtained showed that overall eggs quality was better at the beginning of the spawning period, influencing the larvae performance.O objetivo deste trabalho foi avaliar a qualidade de ovos de peixe-rei ao longo do período reprodutivo. Ovos fertilizados foram amostrados em setembro, outubro, novembro e dezembro de reprodutores em cativeiro. O diâmetro do ovo e do vitelo, como também o tamanho das gotículas de óleo diminuíram ao longo do período reprodutivo, com valores maiores em setembro. Taxas de fertilização e eclosão diminuíram ao longo deste período, apresentando valores maiores em setembro (88,0%, 55,2%) e menores em dezembro (43,0%, 25,2%). As larvas eclodidas dos ovos, obtidas em outubro, eram maiores e apresentavam maior peso (8,24 mm; 1,57 mg). A taxa de sobrevivência aos 30 dias pós-eclosão foi maior nos meses de setembro e outubro, apresentando valores similares (66,1%, 62,9%), no entanto, houve uma diminuição acentuada na sobrevivência das larvas de ovos em novembro e dezembro (22,4%, 23,3%). Além disso, o maior peso corporal (15,1 mg) e o comprimento total (15,25 mm) aos 30 dias pós-eclosão foram obtidos a partir de larvas de ovos durante o mês de outubro. Os resultados obtidos mostraram que a qualidade dos ovos em geral foi melhor no início do período reprodutivo, influenciando o desempenho das larvas.Fil: Chalde, Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; ArgentinaFil: Elisio, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; ArgentinaFil: Miranda, Leandro Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas ; Argentin

Robust dual reconstruction systems and fusion frames

We study the duality of reconstruction systems, which are g-frames in a finite dimensional setting. These systems allow redundant linear encoding-decoding schemes implemented by the so-called dual reconstruction systems. We are particularly interested in the projective reconstruction systems that are the analogue of fusion frames in this context. Thus, we focus on dual systems of a fixed projective system that are optimal with respect to erasures of the reconstruction system coefficients involved in the decoding process. We consider two different measures of the reconstruction error in a blind reconstruction algorithm. We also study the projective reconstruction system that best approximate an arbitrary reconstruction system, based on some well known results in matrix theory. Finally, we present a family of examples in which the problem of existence of a dual projective system of a reconstruction system of this type is considered.Fil: Massey, Pedro Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Ruiz, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Stojanoff, Demetrio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

Percus-Yevick theory for the structural properties of the seven-dimensional hard-sphere fluid

The direct correlation function and the (static) structure factor for a seven-dimensional hard-sphere fluid are considered. Analytical results for these quantities are derived within the Percus-Yevick theoryComment: 3 pages, 2 tables, 1 figure; v2: minor changes; to be published in JC

Duality in reconstruction systems

We consider reconstruction systems (RS's), which are G-frames in a finite dimensional setting, and that includes the fusion frames as projective RS's. We describe the spectral picture of the set of RS operators for the projective systems with fixed weights. We also introduce a functional defined on dual pairs of RS's, called the joint potential, and study the structure of the minimizers of this functional. In the case of irreducible RS's the minimizers are characterize as the tight systems. In the general case we give spectral and geometric characterizations of the minimizers of the joint potential. At the end of the paper we show several examples that illustrate our results.Fil: Massey, Pedro Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matemáticas; ArgentinaFil: Ruiz, Mariano Andres. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matemáticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Stojanoff, Demetrio. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matemáticas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

Test of a universality ansatz for the contact values of the radial distribution functions of hard-sphere mixtures near a hard wall

Recent Monte Carlo simulation results for the contact values of polydisperse hard-sphere mixtures at a hard planar wall are considered in the light of a universality assumption made in approximate theoretical approaches. It is found that the data seem to fulfill the universality ansatz reasonably well, thus opening up the possibility of inferring properties of complicated systems from the study of simpler onesComment: 9 pages, 2 figures; v2: minor changes; to be published in the special issue of Molecular Physics dedicated to the Seventh Liblice Conference on the Statistical Mechanics of Liquids (Lednice, Czech Republic, June 11-16, 2006

Oblique projections and frames

We characterize those frames on a Hilbert space H which can be represented as the image of an orthonormal basis by an oblique projection defined on an extension K of H. We show that all frames with infinite excess, and frame bounds 1 ≤ A ≤ B,are of this type. This gives a generalization of a result of Han and Larson which only holds for normalized tight frames.Fil: Antezana, Jorge Abel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Corach, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Ruiz, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Stojanoff, Demetrio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentin

A duality result on frame and Riesz sequences

In this article we present a short proof of a duality principle concerning frame and Riesz sequences due to Ulanovskii and Olevskii. Our proof is derived from a result on compression on orthogonal projections. As a consequence, we get a better lower frame (Riesz) bound for the sequences than the one deduced from the original proof.Fil: Calderón, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Ruiz, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaVII Congreso de Matemática Aplicada, Computacional e IndustrialCórdobaArgentinaMatemática Aplicada, Computacional e IndustrialUniversidad Nacional de Rio Cuarto. Facultad de Ciencias Exactas, Físico-Química y Naturale

Minimization of convex functionals over frame operators

We present results about minimization of convex functionals defined over a finite set of vectors in a finite-dimensional Hilbert space, that extend several known results for the Benedetto-Fickus frame potential. Our approach depends on majorization techniques. We also consider some perturbation problems, where a positive perturbation of the frame operator of a set of vectors is realized as the frame operator of a set of vectors which is close to the original oneFil: Massey, Pedro Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderon; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matematicas; ArgentinaFil: Ruiz, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderon; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Matematicas; Argentin

Revision sistematica de “canis” ensenadensis ameghino 1888 (carnivora, canidae) y la des- cripcion de un nuevo especimen del Pleistoceno de Argentina.

The fossil record of foxes in South America is very rich, with almost all extant South American species recorded. Currently, three fossil species are known in the Plio-Pleistocene of South America: "Dusicyon" cultridens, Dusicyon avus and "Canis" ensenadensis. In the present work we reviewed the systematics of "Canis" ensenadensis from the Pleistocene of Buenos Aires province using both qualitative and quantitative approaches. We also described a new fossil specimen (MCA 2082) from Buenos Aires Province (Argentina) that shares some similarities with "Canis" ensenadensis. We compared the fossil specimens with a large sample of specimens that includes the living species Lycalopex gymnocercus, L. culpaeus, Cerdocyon thous, L. fulvipes, L. vetulus, L. sechurae and Atelocynus microtis. We performed a Principal Component Analysis using mandibular and dental measurements, and then a geometric morphometric analysis using photographs of the lateral view of the mandible. Our results indicate that "Canis" ensenadensis is a valid species and it should be included in the genus Lycalopex. We also conclude that MCA 2082 is a member of the genus Lycalopex, probably belonging to the species L. ensenadensis. These results suggest that the biochron of L. ensenadensis reaches the Lujanian Age. Even if our assignation of MCA 2082 is incorrect, this specimen represents a different taxon from those already described for the Lujanian, thus the diversity of foxes during the Lujanian is greater than previously known.El registro fósil de zorros en América del Sur es muy rico con prácticamente todas las especies sur americanas actuales representadas en él. En la actualidad se conocen tres especies extintas para el Plio-Pleistoceno de América del Sur. “Dusicyon” cultridens, Dusicyon avus y “Canis” ensenadensis. En el presente trabajo hemos reestu- diado la sistemática de “Canis” ensenadensis del Pleistoceno de la provincia de Buenos Aires abordando enfoques cualitativos y cuantitativos. Además describimos un nuevo espécimen proveniente de la Provincia de Buenos Aires (Argentina) que comparte ciertas características con “Canis” ensenadensis. Los especímenes fósiles fueron comparados con una gran muestra de especímenes actuales correspondientes a las espe- cies L. gymnocercus, L. culpaeus, Cerdocyon thous, L. fulvipes, L. vetulus, L. sechurae y Atelocynus microtis. Se realizó un Análisis de Componentes Principales, utilizando medidas mandibulares y dentarias, y un análisis de morfometría geométrica, utilizando fotografías de vistas laterales de la mandíbula. Nuestros resultados sugieren que “Canis” ensenadensis es una especie válida y que debe ser incluida en el género Lycalopex. Además concluímos que MCA 2082 es un miembro del género Lycalopex, perteneciendo tentativamente a la especie Lycalopex ensenadensis. Esto sugiere que el biocrón de Lycalopex ensenadensis alcanzaría la Edad Lujanense. Incluso si nuestra asignación fuese incorrecta, el espéci- men representaría una especie distinta a las descriptas para el Lujanense, por lo que la diversidad de zorros del Lujanense es mayor a la pre- viamente conocida.Fil: Ramirez, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; ArgentinaFil: Prevosti, Francisco Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "bernardino Rivadavia"; Argentina. Universidad Nacional de Luján; Argentin