Possible inclusion of fish waste (scales and fins) in the diet of fishes in aquaculture

The scales and fins of some freshwater fish species (Sarotherodon galilaeus, Oreochromis niloticus, Tilapia zillii, Barbus callipterus, Hemichromis fasciatus) from Kainji Lake, Nigeria were analyzed for their organic and inorganic matter. The aim of such study is to determine the usefulness of these waste parts of the fish in fish feed preparation. In all instances, the inorganic matter was found to be quite high in the fish exoskeleton, and calcium formed the highest element in the scales and the fins. These waste materials are therefore, considered as possible replacement for mineral sources in fish feed and probably the feed for other livestock

Managing Nile perch using slot size: is it possible?

The fishery of Lake Victoria became a major commercial fishery with the introduction of Nile perch in 1950s and 1960s. Biological and population characteristics point to a fishery under intense fishing pressure attributed to increased capacity and use of illegal fishing gears. Studies conducted between 1998 to 2000 suggested capture of fish between slot size of 50 to 85 cm TL to sustain the fishery. Samples from Kenya and Uganda factories in 2008 showed that 50% and 71% of individuals processed were below the slot size respectively. This study revealed that fish below and above the slot has continued being caught and processed. This confirms that the slot size is hardly adhered to by both the fishers and the processors. The paper explores why the slot size has not been a successful tool in management of Nile perch and suggests strategies to sustain the fishery

Expression of eph-family receptor tyrosine kinases and ephrins in the tadpole of the frog Xenopus laevis, and possible roles in the development of retinotectal topography

Assembling a nervous system requires exquisite specificity in the construction of neuronal connectivity. One method by which such specificity is implemented is the presence of chemical cues within the tissues, differentiating one region from another, and the presence of receptors for those cues on the surface of neurons and their axons that are navigating within this cellular environment.

Connections from one part of the nervous system to another often take the form of a topographic mapping. One widely studied model system that involves such a mapping is the vertebrate retinotectal projection-the set of connections between the eye and the optic tectum of the midbrain, which is the primary visual center in non-mammals and is homologous to the superior colliculus in mammals. In this projection the two-dimensional surface of the retina is mapped smoothly onto the two-dimensional surface of the tectum, such that light from neighboring points in visual space excites neighboring cells in the brain. This mapping is implemented at least in part via differential chemical cues in different regions of the tectum.

The Eph family of receptor tyrosine kinases and their cell-surface ligands, the ephrins, have been implicated in a wide variety of processes, generally involving cellular movement in response to extracellular cues. In particular, they possess expression patterns-i.e., complementary gradients of receptor in retina and ligand in tectum- and in vitro and in vivo activities and phenotypes-i.e., repulsive guidance of axons and defective mapping in mutants, respectively-consistent with the long-sought retinotectal chemical mapping cues.

The tadpole of Xenopus laevis, the South African clawed frog, is advantageous for in vivo retinotectal studies because of its transparency and manipulability. However, neither the expression patterns nor the retinotectal roles of these proteins have been well characterized in this system. We report here comprehensive descriptions in swimming stage tadpoles of the messenger RNA expression patterns of eleven known Xenopus Eph and ephrin genes, including xephrin-A3, which is novel, and xEphB2, whose expression pattern has not previously been published in detail. We also report the results of in vivo protein injection perturbation studies on Xenopus retinotectal topography, which were negative, and of in vitro axonal guidance assays, which suggest a previously unrecognized attractive activity of ephrins at low concentrations on retinal ganglion cell axons. This raises the possibility that these axons find their correct targets in part by seeking out a preferred concentration of ligands appropriate to their individual receptor expression levels, rather than by being repelled to greater or lesser degrees by the ephrins but attracted by some as-yet-unknown cue(s).

Comparative limnology of waters in a coniferous forest: is a generalisation possible?

The high density of meres and mosses in the Delamere area comes from numerous moraine-hollows formed after the melting of stranded ice-blocks following last glaciation. The main vegetation is of conifers along with some deciduous species and the area was designated as a National Forest Park in 1987. It has been managed since the beginning of the 19th century and is a popular tourist area with walking, orienteering, cycling and educational activities. In recent years this forest park has been attracting over half a million people per year. This paper studies the limnology of different aquatic habitats in the Delamere Forest area in order to give some insight into the waters of a coniferous, temperate forest area, which has so far been largely unexplored. The authors assume therefore, thought that despite apparent large variability in origin, age, surface area, morphometry, catchment size and hydraulic regime, the waters of Delamere Forest might share some revealing chemical and biological features. Seven water-bodies in the Delamere Forest Park area, namely, Black Lake, Blakemere Moss, Delamere Lake, Delamere Quarry, Hatchmere, Windyhowe Farm Spring and Fir Brook were sampled, their water chemistry and dissolved organic carbon and the occurrence of phytoplankton and zooplankton species examined. In a final chapter the authors analyse their findings for patterns.

International communication strategy followed by Ikea : analysis of campaigns in different countries, features and possible justifications of the differences

International communication strategy followed by Ikea analysis of campaigns in different countries, features and possible justifications of the differerences.

Polyphemus pediculus (L.) (Cladocera) as a possible indicator of water quality

Usually stenobiotic species are used as hydrobiological indicators of the degree of pollution in natural waters. Cladocera are eurybiotic organisms, therefore their role as specific indicators of the water quality is considered to be insignificant. However, considering new methods Cladocera at present are more and more often used as indicators of oligo- and mesosaprobic waters as well as of the presence of considerable amounts of easily degradable organic matter. Work over many years on the biology of Polyphemus pediculus, this striking representative of the order Cladocera, convinced the author of the possibility of using this species not only as an indicator of water purity but also for the estimation of the degree of water pollution as well as of water characteristics such as colour, turbidity, oxgen content and chemical composition. P. pediculus is one of the most common and abundant species of planktonic crustaceans in shallow waters of reservoirs, rivers, lakes, ponds and temporary water bodies.

Calcite covering of sediment as a possible way of curbing blue-green algae

Natural calcite precipitation in lakes is a well-known control mechanism of eutrophication. In hard-water lakes, calcite deposits on the flat bottoms of shallow lakes and near the shores of deeper lakes resulted from biogenic decalcification during the millenia after the last glacial period. The objective of a new restoration technology is to intensify the natural process of precipitation by utilizing the different qualities of calcareous mud layers. In a pilot experiment in Lake Rudower See, East Germany, phosphorus-poor deeper layers of the sediments were flushed out and spread over the phosphorus-rich uppermost sediments, to promote the co- precipitation of calcite with phosphorus from the water-column.

Self-Organized Criticality, Plasticity and Sensorimotor Coupling. Explorations with a Neurorobotic Model in a Behavioural Preference Task

During the last two decades, analysis of 1/f noise in cognitive science has led to a considerable progress in the way we understand the organization of our mental life. However, there is still a lack of specific models providing explanations of how 1/f noise is generated in coupled brain-body-environment systems, since existing models and experiments typically target either externally observable behaviour or isolated neuronal systems but do not address the interplay between neuronal mechanisms and sensorimotor dynamics. We present a conceptual model of a minimal neurorobotic agent solving a behavioural task that makes it possible to relate mechanistic (neurodynamic) and behavioural levels of description. The model consists of a simulated robot controlled by a network of Kuramoto oscillators with homeostatic plasticity and the ability to develop behavioural preferences mediated by sensorimotor patterns. With only three oscillators, this simple model displays self-organized criticality in the form of robust 1/f noise and a wide multifractal spectrum. We show that the emergence of self-organized criticality and 1/f noise in our model is the result of three simultaneous conditions: a) non-linear interaction dynamics capable of generating stable collective patterns, b) internal plastic mechanisms modulating the sensorimotor flows, and c) strong sensorimotor coupling with the environment that induces transient metastable neurodynamic regimes. We carry out a number of experiments to show that both synaptic plasticity and strong sensorimotor coupling play a necessary role, as constituents of self-organized criticality, in the generation of 1/f noise. The experiments also shown to be useful to test the robustness of 1/f scaling comparing the results of different techniques. We finally discuss the role of conceptual models as mediators between nomothetic and mechanistic models and how they can inform future experimental research where self-organized critically includes sensorimotor coupling among the essential interaction-dominant process giving rise to 1/f noise.

A prova do dolo

O trabalho tem como objetivo perscrutar os métodos de prova do dolo, no direito penal, a fim de avaliar se esses métodos são eficientes, de modo a determinar se é possível, enfim, a prova do dolo; investiga-se, ainda, se é necessária ou possível a mudança do próprio conceito de dolo. Na primeira parte, é apresentada a conceituação de dolo, com base nos principais autores do direito penal, com o intuito de delimitar o objeto central do estudo. Para tanto, as diversas controvérsias conceituais são analisadas em concordância com o sistema em que se inserem: escola clássica; causalismo; finalismo; funcionalismo. As demais divergências estão agrupadas em dois grandes blocos as teorias intelectivas e as teorias volitivas em conformidade com o enfoque que é dado pelos autores que defendem esta ou aquela conceituação do dolo. No cerne do trabalho, apresenta-se o método psicanalítico de aferição da consciência e da vontade humanas, para, então, realizar-se o estudo dos métodos de prova adotados no direito penal, sempre cotejado com a análise psicanalítica pertinente, a fim de proporcionar ao leitor uma visão multidisciplinar dos fenômenos subjetivos da mente. Constatar-se-á a insuficiência dos métodos de prova do dolo, no direito penal. Na terceira parte, é feito um estudo da jurisprudência brasileira, no que tange à forma como os tribunais costumam provar o dolo, com o intuito de avaliar se o discurso doutrinário da prova do dolo coaduna-se com a prática judicial. Conclui-se que há, de fato, um descompasso entre o que a doutrina entende como método viável e aquilo que, na prática, é adotado pelos tribunais.