The brooding process in the Chilean oyster, Ostrea chilensis (Philippi, 1845)

Most bivalve molluscs are broadcast spawners, but several have evolved mechanisms for brooding the embryos and larvae. In the research described in this thesis, the Chilean oyster Ostrea chilensis is used as a model to allow us to understand more fully the efficiency of the brooding process and the role of this mode of reproduction as an adaptation to an estuarine environment. The reproductive biology of the adults, the brooding mechanism, and the physiology, behaviour, energetics and morphology of the brooded larvae were studied in oysters from the Quempillen estuary in southern Chile. -- In the Chilean oyster, reproduction occurs once per year, during spring and early summer. During the three years of the study, approximately 40% of the potential females in the population exhibited brooding behaviour. The brooding period was approximately seven to eight weeks, during which larvae lived in the infrabranchial chamber of the female, and grew until they reached approximately 500 jam shell length, after which they were released. Brooded embryos and larvae utilize protein and lipid as the principal energy sources. -- In vivo endoscopic observations showed that larvae were concentrated primarily in the mouth-palps region of the female, where they were constantly manipulated and kept in motion by the palps. However, larvae were also seen distributed along the gills, but with no physical connection to the gills. Larvae showed a clear circulation pattern in the mantle cavity, being transported from the palp region to the posterior region of the gills by the water current produced by the female, then returning to the oral region via the ventral and dorsal ciliated food grooves of the female. -- Larvae were observed to ingest exogenous particles, establishing that they are not obligatory lecithotrophs. Food ingestion began when larvae developed the ciliated velum at approximately 290-300 urn shell length. Observations with the scanning electron microscope revealed that the distribution of ciliary bands on the velum of the Chilean oyster larva is adapted to the unusual environmental conditions associated with brooding. The absence of cilia during all the embryonic stages and the early stages of the veliger, the absence of the apical tuft, and the apparent absence of the postoral cilia (POC) characteristic of pelagic veligers, demonstrate this adaptation. -- The brooding process had a considerable impact on some aspects of the physiology of the female, especially the filtration rate (FR), which greatly decreased in brooding oysters. Brooding females partially compensated by increasing absorption efficiency (AE) in comparison to non brooders. The scope for growth was much lower in brooding oysters than in non brooders, largely as a result of the reduced FR of the brooders. After larvae were liberated, the FR of the female increased, reaching values close to those that could be considered 'normal FR' in Chilean oysters. -- The brooding mechanism provides in the mantle cavity a protective environment in which larvae can develop until they reach a very advanced pediveliger stage before release. Brooding appears in this species to be an adaptation for producing and retaining offspring in the estuarine environment in which Chilean oyster populations occur. Whereas brooding female oysters undergo weight loss, deplete their biochemical reserves, and experience a negative scope for growth during the brooding period, their larvae are liberated at an advanced developmental stage, have a very short pelagic period, and settle immediately after release, implying that mortality is much less than in pelagic larvae

Differences in feeding adaptations in intertidal and subtidal suspension-feeding gastropods: studies on Crepidula fornicata and Crepipatella peruviana

Suspension-feeding organisms living in the intertidal zone experience reduced feeding times associated with periodic aerial exposure. The potential morphological and physiological adaptations to this reduced feeding time were investigated for two closely related gastropods, Crepidula fornicata and Crepipatella peruviana. Intertidal C. fornicata had heavier gills than subtidal conspecifics, a difference mediated by larger gill surface areas and greater numbers of gill filaments among intertidal individuals of a given size. In contrast, the gills of intertidal and subtidal C. peruviana were morphologically indistinguishable. Despite relatively larger food-collecting organs, individuals of C. fornicata from the intertidal zone had clearance rates (CR) that were not significantly different from those of subtidal conspecifics. In contrast, the CR of intertidal C. peruviana were significantly lower than those of subtidal conspecifics. The low CR of intertidal C. peruviana may be partially explained by significantly lower measured particle transport velocities across their gills. In the context of feeding, intertidal individuals of C. fornicata performed at least as well as subtidal conspecifics, resulting in a population whose adults were as large as those found subtidally. This suggests that C. fornicata has had a long interaction with the environmental heterogeneity associated with intertidal life. In contrast, intertidal individuals of C. peruviana were on average smaller than subtidal individuals and may be stressed in the intertidal.Tufts University (Grants-in-aid of research award)Fondo Nacional de Desarrollo Científico y Tecnológico (Chile) (Grant 1100335

UV-R mitigation strategies in encapsulated embryos of the intertidal gastropod Acanthina monodon: A way to compensate for lack of parental care

Intracapsular embryonic development in the intertidal zone exposes embryos to various stress sources characteristic of this environment, including UV-R. They require defensive mechanisms to mitigate its adverse effects. The presence of total carotenoids (TC), and mycosporine-like amino acids (MAAs) was studied in adults, in encapsulated embryos, and in the egg capsule walls of the intertidal gastropod Acanthina monodon. Oxygen consumption rates (OCR) were determined in encapsulated and excapsulated embryos exposed to photosynthetically active radiation (PAR) and PAR + UV-A + UV-B to understand if the capsule wall is a protective structure for encapsulated embryos. The results showed the presence of TC in adult pedal and gonad tissues, and in all encapsulated stages. MAAs were not detected. The physical structure of the capsule wall retained most wavelengths, being particularly efficient in the UV-B range. Excapsulated embryos exposed to PAR + UV-A + UV-B radiation increased its OCR compared to encapsulated embryos, indicating the protective character of the capsule wall.Fil: Cubillos, Victor M.. Universidad Austral de Chile; ChileFil: Salas Yanquin, Luis P.. Universidad Austral de Chile; ChileFil: Buchner Miranda, Joseline. Universidad Austral de Chile; ChileFil: Ramirez, Felipe. Universidad Austral de Chile; ChileFil: Zabala, Maria Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Averbuj, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; ArgentinaFil: Marquez, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto de Biología de Organismos Marinos; Argentina. Universidad Nacional de la Patagonia. Facultad de Ciencias Naturales. Sede Puerto Madryn; ArgentinaFil: Jaramillo, Hans. Universidad Austral de Chile; ChileFil: Chaparro, Oscar R.. Universidad Austral de Chile; Chil

Verificación del diseño de tratamientos superficiales mediante el método MODOT T 72 y la sección 409 del Estado de Missouri y su posible incorporación a la normativa argentina

This paper verifies the relations among the specifications given by the Construction Materials and Transport Department of the State of Missouri, United States –Test Method MoDOT T 72 Sweep Test of Bituminous Surface Treatment Sample– and Section 409–Seal Coat– with the established specifications in the National Road Department folder from Argentina, considering further adjustments arising in the LEMaC in order to get a higher representation in relation to the field. For that purpose, it was designed a simple surface treatment using the dosage method proposed by Tagle –known as the 9-5-3 Rule– and a seal coat with crushing sand. This surface treatment is submitted to the Sweep Test, and taking into account the values given by the Section 409 from MoDOT, the dosage method efficiency is evaluated. The results were analyzed and a comparison was made between the dosage method and the specifications given in Section 409 –according to the seal coat gradation and the losses from the test. National Specifications have no numerical restrictions of such a loss, excepting the field experience and the test results where the surface treatment is already used to produce absence of roughness on a surface and the friction coefficient, besides the material parameters. Based on the experimentation tested a recommendation is given for a possible inclusion into the specifications referred.El presente artículo tiene por objeto observar la relación entre las especificaciones citadas en el Departamento de Transporte de Materiales de Construcción del Estado de Missouri, Estados Unidos “Test Method MoDOT T 72 Sweep Test of Bituminous Surface Treatment Simple” y la Sección 409 “Seal Coat” con las especificaciones establecidas en el Pliego de la Dirección Nacional de Vialidad de la República Argentina, considerando además adecuaciones surgidas en el LEMaC, a efectos de lograr mayor representatividad en relación a la obra. Para llevar a cabo la correlación de lo citado, se diseñó un tratamiento superficial simple con el método de dosificación propuesto por el Ing. Tagle, conocido como la Regla de 9-5-3 y una capa de sello con arena de trituración. Al tratamiento se lo somete al ensayo de barrido, y teniendo en cuenta los valores citados en la Sección 409 del MoDOT, se desea valorar la eficiencia del método de dosificación optado. Se analizaron los resultados obtenidos y se comparó si el método de dosificación con lo estipulado por la Sección 409 de acuerdo a la granulometría de la capa de sellado y las pérdidas derivadas del ensayo. En las Especificaciones Nacionales no existe una restricción numérica de dichas pérdidas sino solo la experiencia de obra y los resultados de ensayos cuando el tratamiento ya está colocado como lisura superficial, rugosidad y coeficiente de fricción, además de los parámetros de los materiales separadamente. Se ha logrado con la experimentación analizada, establecer una recomendación para su posible incorporación a los Pliegos citados

Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good

Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI

Search for stop and higgsino production using diphoton Higgs boson decays

Results are presented of a search for a "natural" supersymmetry scenario with gauge mediated symmetry breaking. It is assumed that only the supersymmetric partners of the top-quark (stop) and the Higgs boson (higgsino) are accessible. Events are examined in which there are two photons forming a Higgs boson candidate, and at least two b-quark jets. In 19.7 inverse femtobarns of proton-proton collision data at sqrt(s) = 8 TeV, recorded in the CMS experiment, no evidence of a signal is found and lower limits at the 95% confidence level are set, excluding the stop mass below 360 to 410 GeV, depending on the higgsino mass