Genericity aspects in gravitational collapse to black holes and naked singularities

We investigate here the genericity and stability aspects for naked singularities and black holes that arise as the final states for a complete gravitational collapse of a spherical massive matter cloud. The form of the matter considered is a general Type I matter field, which includes most of the physically reasonable matter fields such as dust, perfect fluids and such other physically interesting forms of matter widely used in gravitation theory. We first study here in some detail the effects of small pressure perturbations in an otherwise pressure-free collapse scenario, and examine how a collapse evolution that was going to the black hole endstate would be modified and go to a naked singularity, once small pressures are introduced in the initial data. This allows us to understand the distribution of black holes and naked singularities in the initial data space. Collapse is examined in terms of the evolutions allowed by Einstein equations, under suitable physical conditions and as evolving from a regular initial data. We then show that both black holes and naked singularities are generic outcomes of a complete collapse, when genericity is defined in a suitable sense in an appropriate space.Comment: 24 pages, 6 figures, some changes in text and figures to match the version accepted for publication by IJMP

A Fast Parallelized Computational Approach Based on Sparse LU Factorization for Predictions of Spatial and Time-Dependent Currents and Voltages in Full-Body Biomodels

Realistic and accurate numerical simulations of electrostimulation of tissues and full-body biomodels have been developed and implemented. Typically, whole-body systems are very complex and consist of a multitude of tissues, organs, and subcomponents with diverse properties. From an electrical standpoint, these can be characterized in terms of separate conductivities and permittivities. Accuracy demands good spatial resolution; thus, the overall tissue/animal models need to be discretized into a fine-grained mesh. This can lead to a large number of grid points (especially for a three-dimensional entity) and can place prohibitive requirements of memory storage and execution times on computing machines. Here, the authors include a simple yet fast and efficient numerical implementation. It is based on LU decomposition for execution on a cluster of computers running in parallel with distributed storage of the data in a sparse format. In this paper, the details of electrical tissue representation, the fast algorithm, the relevant biomodels, and specific applications to whole-animal studies of electrostimulation are discussed

Preparation and characterization of protein-nanotube conjugates

This chapter describes methods of immobilizing proteins on carbon nanotubes, using two different routes—physical adsorption and covalent attachment. We also provide an overview on how such conjugates can be characterized with the help of various techniques, such as Raman, Fourier transform infrared (FT-IR), circular dichroism (CD), and fluorescence spectroscopies, in addition to the standard enzyme kinetic analyses of activity and stability. Both the attachment routes—covalent and noncovalent—could be used to prepare protein conjugates that retained a significant fraction of their native structure and function; furthermore, the protein conjugates were operationally stable, reusable, and functional even under harsh denaturing conditions. These studies therefore corroborate the use of these immobilization methods to engineer functional carbon nanotube-protein hybrids that are highly active and stable

Seasonal abundance and host plants of coconut stick insect (Graeffea crouanii Le Guillou) in coconut plantations of Fiji islands

Field survey conducted in major coconut growing regions in the three Fiji islands viz., Viti Levu, Vanua Levu, and Taveuni, revealed the presence of only one pest species of stick insect, Graeffea crouanii. Temperature had a significant effect on the level of infestation in the farms surveyed, while the effect of rainfall and humidity on the infestation was insignificant. Severe infestation was observed in isolated pockets, and the pest distribution was discontinuous in the surveyed areas. On a damage scale index, the insect infestation on coconut palms ranged from 0 to 4 grades. The peak increase of G. crouanii populations was from November to April in wet season at each of the three hotspots: Namaumada (Viti Levu), Dawara (Vanua Levu), and Salialevu (Taveuni). The occurrence of G. crouanii at varying damage levels in the present study may be attributed to the presence of sparse coconut palms in isolated coconut plantations. The field survey identified many alternate host plants of G. crouanii in the two plant families viz., Arecaceae and Pandanaceae. The information on the seasonal abundance and infestation levels of G. crouanii and its alternate host plants are discussed in formulating location-specific pest management strategies

Symbionts and diseases associated with invasive apple snails

This contribution summarizes knowledge of organisms associated with apple snails, mainly Pomacea spp., either in a facultative or obligate manner, paying special attention to diseases transmitted via these snails to humans. A wide spectrum of epibionts on the shell and operculum of snails are discussed. Among them algae, ciliates, rotifers, nematodes, flatworms, oligochaetes, dipterans, bryozoans and leeches are facultative, benefitting from the provision of substrate, transport, access to food and protection. Among obligate symbionts, five turbellarian species of the genus Temnocephala are known from the branchial cavity, with T. iheringi the most common and abundant. The leech Helobdella ampullariae also spends its entire life cycle inside the branchial cavity; two copepod species and one mite are found in different sites inside the snails. Details of the nature of the relationships of these specific obligate symbionts are poorly known. Also, extensive studies of an intracellular endosymbiosis are summarized. Apple snails are the first or second hosts of several digenean species, including some bird parasites. A number of human diseases are transmitted by apple snails, angiostrongyliasis being the most important because of the potential seriousness of the disease.Facultad de Ciencias Naturales y Muse

Symbionts and diseases associated with invasive apple snails

This contribution summarizes knowledge of organisms associated with apple snails, mainly Pomacea spp., either in a facultative or obligate manner, paying special attention to diseases transmitted via these snails to humans. A wide spectrum of epibionts on the shell and operculum of snails are discussed. Among them algae, ciliates, rotifers, nematodes, flatworms, oligochaetes, dipterans, bryozoans and leeches are facultative, benefitting from the provision of substrate, transport, access to food and protection. Among obligate symbionts, five turbellarian species of the genus Temnocephala are known from the branchial cavity, with T. iheringi the most common and abundant. The leech Helobdella ampullariae also spends its entire life cycle inside the branchial cavity; two copepod species and one mite are found in different sites inside the snails. Details of the nature of the relationships of these specific obligate symbionts are poorly known. Also, extensive studies of an intracellular endosymbiosis are summarized. Apple snails are the first or second hosts of several digenean species, including some bird parasites. A number of human diseases are transmitted by apple snails, angiostrongyliasis being the most important because of the potential seriousness of the disease.Facultad de Ciencias Naturales y Muse

Describing selected populations of the rice black bugs in the Philippines using Correlation Analysis Based on Distances (CORIANDIS)

Morphological shape variations of biological structures have been considered an important factor that affects the survival pattern of an organism. This study focuses to gain information on intraspecific variation among different populations of the rice black bugs (RBBs) using Correlation Analysis Based on Distances (CORIANDIS) from the generated relative warp scores of landmark-based geometric morphometrics. Results revealed that the shapes of genital plates have largely contributed a high observable disparity in all morphological characters. The shapes of the head and forewings also contributed noticeable variations while minimal variances were observed in the shapes of the scutellum and pronotum, respectively. The species/group projected plot among populations are clustered together except Bohol and Leyte populations which show a departure from other populations based from the centroid in the compromise space. The quality of the compromise is 52.99% for males and 51.40% for females. It was noticeable that the trait variance is unproportioned to the area occupied by datasets indicating population differentiation from other populations. These results indicate that geographic variations among populations of RBBs were contributed by high species’ divergence of the combined characters. This study suggests that CORIANDIS is a useful tool in describing population variability as this has the capacity to integrate all available morphological characters of populations to be able to visualize the underlying relationships among populations

Apple snail perivitellins, multifunctional egg proteins

Egg reserves of most gastropods are accumulated surrounding the fertilised oocyte as a perivitelline fluid (PVF). Its proteins, named perivitellins, play a central role in reproduction and development, though there is little information on their structural-functional features. Studies of mollusc perivitellins are limited to Pomacea. A proteomic study of the eggs of P. canaliculata identified over 59 proteins in the PVF, most of which are of unknown function, and have not been isolated and characterised. Information on molecular structure of the most abundant perivitellins of P. canaliculata have shown that they possess other functions besides being storage proteins, most remarkably in defence against predation and abiotic factors. They are a cocktail containing at least neurotoxic, antinutritive and antidigestive perivitellins, with others that may provide the eggs with a bright and conspicuous colour (aposematic signal). This review compiles the current knowledge of Pomacea perivitellins with emphasis on the novel physiological roles they play in the reproductive biology of these gastropods that have evolved the ability to lay their eggs above the water.Facultad de Ciencias Médica

Apple snail perivitellins, multifunctional egg proteins

Egg reserves of most gastropods are accumulated surrounding the fertilised oocyte as a perivitelline fluid (PVF). Its proteins, named perivitellins, play a central role in reproduction and development, though there is little information on their structural-functional features. Studies of mollusc perivitellins are limited to Pomacea. A proteomic study of the eggs of P. canaliculata identified over 59 proteins in the PVF, most of which are of unknown function, and have not been isolated and characterised. Information on molecular structure of the most abundant perivitellins of P. canaliculata have shown that they possess other functions besides being storage proteins, most remarkably in defence against predation and abiotic factors. They are a cocktail containing at least neurotoxic, antinutritive and antidigestive perivitellins, with others that may provide the eggs with a bright and conspicuous colour (aposematic signal). This review compiles the current knowledge of Pomacea perivitellins with emphasis on the novel physiological roles they play in the reproductive biology of these gastropods that have evolved the ability to lay their eggs above the water.Facultad de Ciencias Médica