Cod Year-class Variations and Abundance of Other Commercial Fish in NAFO Divisions 3NO

Possible biological relationships of cod (Gadus morhua) with other important commercial fishes are explored. Cod year-class variations are compared with variations of yellowtail flounder and American plaice spawning biomass, mackerel age 1+ group abundance, and redfish densities. The adult fish biomass of these species are considered as an index of their egg and larval abundances. Possible competitive and predator-prey relationships between the 0-age groups and young individuals of cod and these species are examined through correlation analyses. No significant relationships between cod and redfish and yellowtail flounder were found. It seems that mackerel is a predator on cod larvae. A positive high correlation between spawning American plaice biomass and cod year-class strength was found. High American plaice spawning biomass may promote high cod recruitment through a predator-prey interaction. Alternatively, both species may respond similarly to an environmental signal

Year-class Variations of American Plaice and Yellowtail Flounder in Div. 3LNO and the Abundance of Other Commercial Fish

In a previous paper (Paz and Larrafieta, 1989) we obtained a significant positive correlation between cod year-class size in Div. 3NO and American plaice spawning biomass in Div. 3LNO, that was interpreted by supposing a strong predation of 0-group cod on 0-group American plaice. On the contrary, we have not found significant correlations between cod year-classes and spawning biomasses of other species in the area as redfish, yellowtail and mackerel. Following the same method, in this paper we explore correlations between American plaice (Hippoglossoides platessoides) and yellowtail flounder (Limanda ferruginea) year-class sizes and biomasses of adult fishes of these species and those of cod (Cactus morhua), mackerel (Scomber seombrus) and redfishes (Sebastes app.

Testing Non-parametric Methods to Estimate Cod (Gadus morhua) Recruitment in NAFO Divisions 3NO

Recognizing that non-parametric methods to estimate fish stock recruitment are generally simple and they do not need to be based on ecological hypotheses, four non-parametric methods; the probability transition matrix and three algorithms to estimate recruitment probability density functions were tested on cod (Gadus morhua) data from NAFO Div. 3NO. The transition matrix method was inadequate because the cod stock failed to meet the primary Markovian assumption: the transition probability must be constant and depend only on the previous state. Of the three algorithm methods, the fixed-interval, the New England and the Cauchy, only the New England was appropriate for calculating recruitment with these stock data. A regression coefficient of r = 0.556 (d.f. = 23, P = 0.003) was obtained when the observed data were compared with the estimated. The validity of estimates of future recruitment using the New England algorithm depends on biotic and abiotic environmental conditions being similar in both the pre-recruit and the observation periods

Cod Stock-Recruitment Relationship in NAFO Divisions 3NO

The cod stock-recruitment relationships in NAFO Div. 3NO were studied by the basic Ricker model and modified Ricker model. Although the models do not adjust to the empirical data, inclusion of the American plaice spawning biomass improves the fit. Adding the mackerel adult biomass also improves the model. Including these two variables in the Ricker model explains almost all variation of the cod stock-recruitment relationship in the area. The confidence level of the parameters in the proposed equation were determined by the bootstrap technique, and its accuracy tested. Was realized a simulation study was performed. The response surfaces show the relations between the four variables studied

La profesión periodística española a la deriva

La profesión periodística española está sufriendo una transformación integral, que afecta a la calidad de “lo publicado” y a la “percepción de la opinión pública”. La precariedad de los medios de comunicación, especialmente los tradicionales, está reduciendo dramáticamente la calidad de los trabajos periodísticos, lo cual entra en conflicto con los eslóganes del periodismo que son axiomáticos: 1) sin periodismo no hay democracia; 2) sin democracia no hay periodismo, 3) sin ellos no hay opinión pública. Se precisa un nuevo modo de pensar y de hacer el periodismo, desde la formación y el desarrollo de la profesión. Metodológicamente, además de presentar datos estadísticos significativos para poder analizar la evolución de la profesión, se parte del ethical witnessing profesional, que tiene como punto de partida la observación profesional desde el “deber ser”, desde los imperativos profesionales para que el Periodismo pueda cumplir con todas sus funciones sociales. La revisión profesional desde la teoría y la praxis arrojan unos resultados que evidencian la necesidad de un nuevo paradigma periodístico, recuperando para ello todos los principios rectores desde la profesión, desde las últimas tecnologías. Solo una conciliación armónica de los fundamentos periodísticos clásicos del periodismo, junto a la aplicación de las más innovadoras tecnologías, devolverán al periodismo el lugar social, económico y político que nunca debió haber abandonado

Trustworthy placements: Improving quality and resilience in collaborative attack detection

Abstract In distributed and collaborative attack detection systems decisions are made on the basis of the events reported by many sensors, e.g., Intrusion Detection Systems placed across various network locations. In some cases such events originate at locations over which we have little control, for example because they belong to an organisation that shares information with us. Blindly accepting such reports as real encompasses several risks, as sensors might be dishonest, unreliable or simply having been compromised. In these situations trust plays an important role in deciding whether alerts should be believed or not. In this work we present an approach to maximise the quality of the information gathered in such systems and the resilience against dishonest behaviours. We introduce the notion of trust diversity amongst sensors and argue that detection configurations with such a property perform much better in many respects. Using reputation as a proxy for trust, we introduce an adaptive scheme to dynamically reconfigure the network of detection sensors. Experiments confirm an overall increase both in detection quality and resilience against compromise and misbehaviour

Trustworthy placements: Improving quality and resilience in collaborative attack detection

Abstract In distributed and collaborative attack detection systems decisions are made on the basis of the events reported by many sensors, e.g., Intrusion Detection Systems placed across various network locations. In some cases such events originate at locations over which we have little control, for example because they belong to an organisation that shares information with us. Blindly accepting such reports as real encompasses several risks, as sensors might be dishonest, unreliable or simply having been compromised. In these situations trust plays an important role in deciding whether alerts should be believed or not. In this work we present an approach to maximise the quality of the information gathered in such systems and the resilience against dishonest behaviours. We introduce the notion of trust diversity amongst sensors and argue that detection configurations with such a property perform much better in many respects. Using reputation as a proxy for trust, we introduce an adaptive scheme to dynamically reconfigure the network of detection sensors. Experiments confirm an overall increase both in detection quality and resilience against compromise and misbehaviour

Parallel Multi-Objective Evolutionary Algorithms: A Comprehensive Survey

Multi-Objective Evolutionary Algorithms (MOEAs) are powerful search techniques that have been extensively used to solve difficult problems in a wide variety of disciplines. However, they can be very demanding in terms of computational resources. Parallel implementations of MOEAs (pMOEAs) provide considerable gains regarding performance and scalability and, therefore, their relevance in tackling computationally expensive applications. This paper presents a survey of pMOEAs, describing a refined taxonomy, an up-to-date review of methods and the key contributions to the field. Furthermore, some of the open questions that require further research are also briefly discussed

A conjecture on Exceptional Orthogonal Polynomials

Exceptional orthogonal polynomial systems (X-OPS) arise as eigenfunctions of Sturm-Liouville problems and generalize in this sense the classical families of Hermite, Laguerre and Jacobi. They also generalize the family of CPRS orthogonal polynomials. We formulate the following conjecture: every exceptional orthogonal polynomial system is related to a classical system by a Darboux-Crum transformation. We give a proof of this conjecture for codimension 2 exceptional orthogonal polynomials (X2-OPs). As a by-product of this analysis, we prove a Bochner-type theorem classifying all possible X2-OPS. The classification includes all cases known to date plus some new examples of X2-Laguerre and X2-Jacobi polynomials