A matching pursuit-based signal complexity measure for the analysis of newborn EEG

This paper presents a new relative measure of signal complexity, referred to here as relative structural complexity, which is based on the matching pursuit (MP) decomposition. By relative, we refer to the fact that this new measure is highly dependent on the decomposition dictionary used by MP. The structural part of the definition points to the fact that this new measure is related to the structure, or composition, of the signal under analysis. After a formal definition, the proposed relative structural complexity measure is used in the analysis of newborn EEG. To do this, firstly, a time-frequency (TF) decomposition dictionary is specifically designed to compactly represent the newborn EEG seizure state using MP. We then show, through the analysis of synthetic and real newborn EEG data, that the relative structural complexity measure can indicate changes in EEG structure as it transitions between the two EEG states; namely seizure and background (non-seizure).

Structural complexity in indium selenides prepared using bicyclic amines as structure-directing agents

The synthesis and characterization of five new indium selenides, [C9H17N2]3[In5Se8+x(Se2)1−x] (1–2), [C6H12N2]4[C6H14N2]3[In10Se15(Se2)3] (3), [C6H14N2][(C6H12N2)2NaIn5Se9] (4) and [enH2][NH4][In7Se12] (5), are described. These materials were prepared under solvothermal conditions, using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,4-diazabicyclo[2.2.2]octane (DABCO) as structure-directing agents. Compounds 1–4 represent the first examples of ribbons in indium selenides, and 4 is the first example of incorporation of an alkali metal complex. Compounds 1, 2 and 4 contain closely related [In5Se8+x(Se2)1−x]3− ribbons which differ only in their content of (Se2)2− anions. These ribbons are interspaced by organic countercations in 1 and 2, while in 4 they are linked by highly unusual [Na(DABCO)2]+ units into a three-dimensional framework. Compound 3 contains complex ribbons, with a long repeating sequence of ca. 36 Å, and 4 is a non-centrosymmetric three-dimensional framework, formed as a consequence of the decomposition of DABCO into ethylenediamine (en) and ammonia.

Biomass production and secretion of hydrolytic enzymes are influenced by the structural complexity of the nitrogen source in Fusarium oxysporum and Aspergillus nidulans

The structural complexity of the nitrogen sources strongly affects biomass production and secretion of hydrolytic enzymes in filamentous fungi. Fusarium oxysporum and Aspergillus nidulans were grown in media containing glucose or starch, and supplemented with a nitrogen source varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids), peptides (peptone) and protein (gelatin). In glucose, when the initial pH was adjusted to 5.0, for both microorganisms, higher biomass production occurred upon supplementation with a nitrogen source in the peptide form (peptone and gelatin). With a close to neutrality pH, biomass accumulation was lower only in the presence of the ammonium salt. When grown in starch, biomass accumulation and secretion of hydrolytic enzymes (amylolytic and proteolytic) by Fusarium also depended on the nature of the nitrogen supplement and the pH. When the initial pH was adjusted to 5.0, higher growth and higher amylolytic activities were detected in the media supplemented with peptone, gelatin and casamino acids. However, at pH 7.0, higher biomass accumulation and higher amylolytic activities were observed upon supplementation with peptone or gelatin. Ammonium sulfate and casamino acids induced a lower production of biomass, and a different level of amylolytic enzyme secretion: high in ammonium sulfate and low in casamino acids. Secretion of proteolytic activity was always higher in the media supplemented with peptone and gelatin. Aspergillus, when grown in starch, was not as dependent as Fusarium on the nature of nitrogen source or the pH. The results described in this work indicate that the metabolism of fungi is regulated not only by pH, but also by the level of structural complexity of the nitrogen source in correlation to the carbon source.

Effect of sugar catabolite repression in correlation with the structural complexity of the nitrogen source on yeast growth and fermentation

Biomass and ethanol production by industrial Saccharomyces cerevisiae strains were strongly affected by the structural complexity of the nitrogen source during fermentation in media containing galactose, and supplemented with a nitrogen source varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids) and peptides (peptone). Diauxie was observed at low galactose concentrations independent of nitrogen supplementation. At high sugar concentrations altered patterns of galactose utilisation were observed. Biomass accumulation and ethanol production depended on the nature of the nitrogen source and were different for baking and brewing ale and lager strains. Baking yeast showed improved galactose fermentation performance in the medium supplemented with casamino acids. High biomass production was observed with peptone and casamino acids for the ale brewing strain, however high ethanol production was observed only in the presence of casamino acids. Conversely, peptone was the nitrogen supplement that induced higher biomass and ethanol production for the lager brewing strain. Ammonium salts always induced poor yeast performance. The results with galactose differed from those obtained with glucose and maltose which indicated that supplementation with a nitrogen source in the peptide form (peptone) was more positive for yeast metabolism, suggesting that sugar catabolite repression has a central role in yeast performance in a medium containing nitrogen sources with differing levels of structural complexity.

Structural complexity of the nitrogen source and influence on yeast growth and fermentation

The structural complexity of the nitrogen source strongly affects both biomass and ethanol production by industrial strains of Saccharomyces cerevisiae, during fermentation in media containing glucose or maltose, and supplemented with a nitrogen source varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids) and peptides (peptone). Diauxie was observed at low glucose and maltose concentrations independent of nitrogen supplementation. At high sugar concentrations diauxie was not easily observed. and growth and ethanol production depended on the nature of the nitrogen source. This was different for baking and brewing ale and lager yeast strains. Sugar concentration had a strong effect on the shift from oxido-fermentative to oxidative metabolism. At low sugar concentrations, biomass production was similar under both peptone and casamino acid supplementation. Under casamino acid supplementation, the time for metabolic shift increased with the glucose concentration, together with a decrease in the biomass production. This drastic effect on glucose fermentation resulted in the extinction of the second growth phase, probably due to the loss of cell viability. Ammonium salts always induced poor yeast performance. In general, supplementation with a nitrogen source in the peptide form (peptone) was more positive for yeast metabolism, inducing higher biomass and ethanol production, and preserving yeast viability, in both glucose and maltose media, for baking and brewing ale and lager yeast strains. Determination of amino acid utilization showed that most free and peptide amino acids present, in peptone and casamino acids, were utilized by the yeast, suggesting that the results described in this work were not due to a nutritional status induced by nitrogen limitation.

Temperate Mountain Forest Biodiversity under Climate Change: Compensating Negative Effects by Increasing Structural Complexity

Species adapted to cold-climatic mountain environments are expected to face a high risk of range contractions, if not local extinctions under climate change. Yet, the populations of many endothermic species may not be primarily affected by physiological constraints, but indirectly by climate-induced changes of habitat characteristics. In mountain forests, where vertebrate species largely depend on vegetation composition and structure, deteriorating habitat suitability may thus be mitigated or even compensated by habitat management aiming at compositional and structural enhancement. We tested this possibility using four cold-adapted bird species with complementary habitat requirements as model organisms. Based on species data and environmental information collected in 300 1-km2 grid cells distributed across four mountain ranges in central Europe, we investigated (1) how species’ occurrence is explained by climate, landscape, and vegetation, (2) to what extent climate change and climate-induced vegetation changes will affect habitat suitability, and (3) whether these changes could be compensated by adaptive habitat management. Species presence was modelled as a function of climate, landscape and vegetation variables under current climate; moreover, vegetation-climate relationships were assessed. The models were extrapolated to the climatic conditions of 2050, assuming the moderate IPCC-scenario A1B, and changes in species’ occurrence probability were quantified. Finally, we assessed the maximum increase in occurrence probability that could be achieved by modifying one or multiple vegetation variables under altered climate conditions. Climate variables contributed significantly to explaining species occurrence, and expected climatic changes, as well as climate-induced vegetation trends, decreased the occurrence probability of all four species, particularly at the low-altitudinal margins of their distribution. These effects could be partly compensated by modifying single vegetation factors, but full compensation would only be achieved if several factors were changed in concert. The results illustrate the possibilities and limitations of adaptive species conservation management under climate change.

Structural and Computational Existence Results for Multidimensional Subshifts

Symbolic dynamics is a branch of mathematics that studies the structure of infinite sequences of symbols, or in the multidimensional case, infinite grids of symbols. Classes of such sequences and grids defined by collections of forbidden patterns are called subshifts, and subshifts of finite type are defined by finitely many forbidden patterns. The simplest examples of multidimensional subshifts are sets of Wang tilings, infinite arrangements of square tiles with colored edges, where adjacent edges must have the same color. Multidimensional symbolic dynamics has strong connections to computability theory, since most of the basic properties of subshifts cannot be recognized by computer programs, but are instead characterized by some higher-level notion of computability. This dissertation focuses on the structure of multidimensional subshifts, and the ways in which it relates to their computational properties. In the first part, we study the subpattern posets and Cantor-Bendixson ranks of countable subshifts of finite type, which can be seen as measures of their structural complexity. We show, by explicitly constructing subshifts with the desired properties, that both notions are essentially restricted only by computability conditions. In the second part of the dissertation, we study different methods of defining (classes of ) multidimensional subshifts, and how they relate to each other and existing methods. We present definitions that use monadic second-order logic, a more restricted kind of logical quantification called quantifier extension, and multi-headed finite state machines. Two of the definitions give rise to hierarchies of subshift classes, which are a priori infinite, but which we show to collapse into finitely many levels. The quantifier extension provides insight to the somewhat mysterious class of multidimensional sofic subshifts, since we prove a characterization for the class of subshifts that can extend a sofic subshift into a nonsofic one.

Altered patterns of maltose and glucose fermentation by brewing and wine yeasts influenced by the complexity of nitrogen source

Maltose and glucose fermentations by industrial brewing and wine yeasts strains were strongly affected by the structural complexity of the nitrogen source. In this study, four Saccharomyces cerevisiae strains, two brewing and two wine yeasts, were grown in a medium containing maltose or glucose supplemented with a nitrogen source varying from a single ammonium salt (ammonium sulfate) to free amino acids (casamino acids) and peptides (peptone). Diauxie was observed at low sugar concentration for brewing and wine strains, independent of nitrogen supplementation, and the type of sugar. At high sugar concentrations altered patterns of sugar fermentation were observed, and biomass accumulation and ethanol production depended on the nature of the nitrogen source and were different for brewing and wine strains. In maltose, high biomass production was observed under peptone and casamino acids for the brewing and wine strains, however efficient maltose utilization and high ethanol production was only observed in the presence of casamino acids for one brewing and one wine strain studied. Conversely, peptone and casamino acids induced higher biomass and ethanol production for the two other brewing and wine strains studied. With glucose, in general, peptone induced higher fermentation performance for all strains, and one brewing and wine strain produced the same amount of ethanol with peptone and casamino acids supplementation. Ammonium salts always induced poor yeast performance. The results described in this paper suggest that the complex nitrogen composition of the cultivation medium may create conditions resembling those responsible for inducing sluggish/stuck fermentation, and indicate that the kind and concentration of sugar, the complexity of nitrogen source and the yeast genetic background influence optimal industrial yeast fermentation performance.

Changes in coral reef communities and an associated reef fish species, Cephalopholis cruentata (Lacepede), after 30 years on Curacao (Netherlands Antilles)

Using the same methodology and identical sites, we repeat a study dating from 1973 and quantify cover of hard coral species, soft corals, sponges, hard substratum and soft substratum, and density of a commercially important reef fish species, the graysby Cephalopholis cruentata, along a depth-gradient of 3-36 m oil the coral reefs of Curacao. The objective was to determine the multi-decade change in benthic coral reef cover and structural complexity, and their effect oil densities of an associated reef fish species. Total hard coral cover decreased on average from 52% in 1973 to 22% in 2003, representing a relative decline of 58%. During this time span, the cover of hard substratum increased considerably (from 11 to 58%), as did that of soft corals (from 0.1 to 2.2%), whereas the cover of sponges showed no significant change. Relative decline of hard coral cover and of reef complexity was greatest in shallow waters (near the coast), which is indicative of a combination of anthropogenic influences from shore and recent storm damage. Cover of main reef builder coral species (Agaricia spp., Siderastrea siderea, Montastrea annularis) decreased more than that of other species, and resulted in a significant decrease in reef complexity. Although density of C. cruentata was highly correlated to cover of Montastrea and Agaricia in 1973, the loss of coral cover did not show any effect on the total density of C. cruentata in 2003. However, C. cruentata showed a clear shift in density distribution from shallow water in 1973 to deep water in 2003. It call be concluded that the reefs of Curacao have degraded considerably in the last three decades, but that this has had no major effect on the population size of one commercially important coral-associated fish species.

Biodiversidade de parasitas de peixes da família Loricariidae (Teleostei: Siluriformes) procedentes do rio Sapucaí-Mirim, Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Aproximación metodológica para la identificación del perfil y patrones de colaboración de dominios científicos universitarios

La diversidad temática y complejidad estructural de las universidades nacionales argentinas hacen que la identificación de sus perfiles científicos no resulte sencilla. En este estudio se realiza una aproximación metodológica para el análisis del perfil temático y patrones de colaboración de estos dominios científicos, a partir del estudio bibliométrico de las contribuciones científicas de las facultades que las conforman, sin perder de vista sus posicionamientos relativos respecto de la universidad de la que son parte y del país en su conjunto. Como ejemplo de aplicación de la metodología propuesta se estudia el caso de una facultad, la Facultad de Ciencias Naturales y Museo (FCNyM) de la Universidad Nacional de La Plata (UNLP), Argentina. Se realiza un análisis bibliométrico de sus contribuciones científicas recogidas en el Science Citation Index versión CD-ROM para el período 1991-2000, identificando y comparando su perfil, patrones y posicionamiento científico relativo en los contextos de la UNLP y de Argentina. Los resultados muestran que la metodología propuesta es una alternativa válida tanto para relevar las fortalezas científicas de una universidad como para aportar información cuantitativa y cualitativa de apoyo a la toma de decisiones en materia de planificación y evaluación de sus actividades de investigación

Aproximación metodológica para la identificación del perfil y patrones de colaboración de dominios científicos universitarios

La diversidad temática y complejidad estructural de las universidades nacionales argentinas hacen que la identificación de sus perfiles científicos no resulte sencilla. En este estudio se realiza una aproximación metodológica para el análisis del perfil temático y patrones de colaboración de estos dominios científicos, a partir del estudio bibliométrico de las contribuciones científicas de las facultades que las conforman, sin perder de vista sus posicionamientos relativos respecto de la universidad de la que son parte y del país en su conjunto. Como ejemplo de aplicación de la metodología propuesta se estudia el caso de una facultad, la Facultad de Ciencias Naturales y Museo (FCNyM) de la Universidad Nacional de La Plata (UNLP), Argentina. Se realiza un análisis bibliométrico de sus contribuciones científicas recogidas en el Science Citation Index versión CD-ROM para el período 1991-2000, identificando y comparando su perfil, patrones y posicionamiento científico relativo en los contextos de la UNLP y de Argentina. Los resultados muestran que la metodología propuesta es una alternativa válida tanto para relevar las fortalezas científicas de una universidad como para aportar información cuantitativa y cualitativa de apoyo a la toma de decisiones en materia de planificación y evaluación de sus actividades de investigación

Aproximación metodológica para la identificación del perfil y patrones de colaboración de dominios científicos universitarios

La diversidad temática y complejidad estructural de las universidades nacionales argentinas hacen que la identificación de sus perfiles científicos no resulte sencilla. En este estudio se realiza una aproximación metodológica para el análisis del perfil temático y patrones de colaboración de estos dominios científicos, a partir del estudio bibliométrico de las contribuciones científicas de las facultades que las conforman, sin perder de vista sus posicionamientos relativos respecto de la universidad de la que son parte y del país en su conjunto. Como ejemplo de aplicación de la metodología propuesta se estudia el caso de una facultad, la Facultad de Ciencias Naturales y Museo (FCNyM) de la Universidad Nacional de La Plata (UNLP), Argentina. Se realiza un análisis bibliométrico de sus contribuciones científicas recogidas en el Science Citation Index versión CD-ROM para el período 1991-2000, identificando y comparando su perfil, patrones y posicionamiento científico relativo en los contextos de la UNLP y de Argentina. Los resultados muestran que la metodología propuesta es una alternativa válida tanto para relevar las fortalezas científicas de una universidad como para aportar información cuantitativa y cualitativa de apoyo a la toma de decisiones en materia de planificación y evaluación de sus actividades de investigación