Effects of grazing management on beetle and plant assemblages during the re-creation of a flood-plain meadow

Flood-plain meadows (Alopecurus-Sanguisorba grassland) are a floristically rich community of conservation importance throughout Europe. Declines in their distribution due in part to modern farming practices mean they now cover less than 1500 ha in the UK. To investigate the effect of grazing regime during the re-creation of this grassland type, target plant species were sown onto ex-arable land during 1985. Traditional management, based on a July hay cut followed by aftermath grazing was subsequently instigated, and the site was divided into replicated grazing regimes of cattle, sheep and an un-grazed control. Plant and beetle assemblages were sampled and compared to those of target flood-plain meadows and improved grassland communities. Within the re-creation treatments the absence of aftermath grazing reduced beetle abundances and species richness. Assemblages of plants were closest to that of the target flood-plain meadow under sheep grazing, although this differed little from cattle grazing. Beetle species assemblages and functional group structure were, however, closest to the target grassland under cattle grazing. For all taxa the greatest resilience to succession to the target flood-plain meadow occurred when grazing was not part of the management prescription. Although successful re-creation had not been achieved for either the plants or beetles, cutting followed by aftermath cattle grazing has provided the best management to date. (c) 2006 Elsevier B.V. All rights reserved.

Behavioral changes associated with a population density decline in the facultatively social red fox

Understanding the causal mechanisms promoting group formation in carnivores has been widely investigated, particularly how fitness components affect group formation. Population density may affect the relative benefits of natal philopatry versus dispersal. Density effects on individual behavioral strategies have previously been studied through comparisons of different populations, where differences could be confounded by between-site effects. We used a single population of red foxes (Vulpes vulpes) in the city of Bristol, UK, that underwent a natural perturbation in density to compare key changes in 1) group structure, 2) within-group relatedness, 3) mating system, 4) dispersal, and 5) dominance attainment. At high densities (19.6-27.6 adults km(-2)), group sex ratios were equal and included related and unrelated individuals. At low densities (4.0-5.5 adults km(-2)), groups became female biased and were structured around philopatric females. However, levels of within-group relatedness were unchanged. The genetic mating patterns changed with no instances of multiple-paternity litters and a decline in the frequency of extrapair litters of cubs from <= 77% to <= 38%. However, the number of genetically monogynous groups did not differ between periods. Dispersal was male biased at both high and low densities. At high density, most dominant males in the study groups appeared to have gained dominance after dispersing, but natal philopatry was an equally successful strategy at low density; conversely, most dominant females were philopatric individuals at both high and low densities. These results illustrate how density may alter behavioral strategies such as mating patterns and how this, in turn, alters group structure in a single population.

Influência da composição do grupo (turma escolar), entre crianças da primeira serie do 1. grau, sobre a estrutura sócio-afetiva

Neste estudo discutem-se as influências da forma de composição do grupo (turma escolar), entre crianças da primeira série do 1º Grau, em função da maturidade necessária à aprendizagem da leitura e da escrita, relativamente à estrutura e mudança da estrutura sócio-afetiva. O problema teve origem no questionamento em torno do valor da prática e suas possíveis influências sobre o desenvolvimento social da criança que, por volta dos sete anos de idade - coincidindo com a entrada para a escola - é mais fortemente incrementado. O suporte teórico do estudo é dado pela Teoria de Campo de Kurt Lewin. O percentual de indicações positivas (PIP) , o percentual de indicações negativas (PIN) , o destaque da posição sociométrica (D), a qualidade do destaque (Qd) , e a mudança das posições sociométricas dos indivíduos nos grupos (MPS) , - constituiram-se em indicadores da variável composição do grupo. Do estudo realizado conclui-se que as formas homogênea e heterogênea de composição do grupo influenciaram de maneira não significativamente diferente em relação à estrutura e a mudança da estrutura sócio-afetiva do grupo, sendo, portanto, injustificada a prática da homogeneização das classes escolares em relação a estes aspectos.

Otimização de carteiras regularizadas empregando informações de grupos de ativos para o mercado brasileiro

Este trabalho se dedica a analisar o desempenho de modelos de otimização de carteiras regularizadas, empregando ativos financeiros do mercado brasileiro. Em particular, regularizamos as carteiras através do uso de restrições sobre a norma dos pesos dos ativos, assim como DeMiguel et al. (2009). Adicionalmente, também analisamos o desempenho de carteiras que levam em consideração informações sobre a estrutura de grupos de ativos com características semelhantes, conforme proposto por Fernandes, Rocha e Souza (2011). Enquanto a matriz de covariância empregada nas análises é a estimada através dos dados amostrais, os retornos esperados são obtidos através da otimização reversa da carteira de equilíbrio de mercado proposta por Black e Litterman (1992). A análise empírica fora da amostra para o período entre janeiro de 2010 e outubro de 2014 sinaliza-nos que, em linha com estudos anteriores, a penalização das normas dos pesos pode levar (dependendo da norma escolhida e da intensidade da restrição) a melhores performances em termos de Sharpe e retorno médio, em relação a carteiras obtidas via o modelo tradicional de Markowitz. Além disso, a inclusão de informações sobre os grupos de ativos também pode trazer benefícios ao cálculo de portfolios ótimos, tanto em relação aos métodos tradicionais quanto em relação aos casos sem uso da estrutura de grupos.

Introdução à teoria de homotopia

Pós-graduação em Matemática Universitária - IGCE

Interações entre pré-escolares: possibilidades de análises

Buscou-se, neste trabalho, construir a rede de relações sociais entre pré-escolares e analisar a pertinência das metodologias utilizadas para a coleta e análise dos dados. Participaram dezessete pré-escolares de uma escola privada em Belém-PA. Os dados foram coletados através de teste sociométrico e observação comportamental. A estrutura do grupo foi analisada a partir da rede de relações sociais, construída através de Árvores Geradoras Mínimas (Teoria dos Grafos). Os resultados mostraram preferências por parcerias diferentes no teste sociométrico e no comportamento interativo. As duas medidas complementaram-se. O uso da Teoria dos Grafos demonstrou-se relevante por possibilitar análises quantitativa e qualitativa do fenômeno social.

Implicazioni teoriche e sperimentali della sincronizzazione assoluta nella teoria della relatività speciale

Sono indagate le implicazioni teoriche e sperimentali derivanti dall'assunzione, nella teoria della relatività speciale, di un criterio di sincronizzazione (detta assoluta) diverso da quello standard. La scelta della sincronizzazione assoluta è giustificata da alcune considerazioni di carattere epistemologico sullo status di fenomeni quali la contrazione delle lunghezze e la dilatazione del tempo. Oltre che a fornire una diversa interpretazione, la sincronizzazione assoluta rappresenta una estensione del campo di applicazione della relatività speciale in quanto può essere attuata anche in sistemi di riferimento accelerati. Questa estensione consente di trattare in maniera unitaria i fenomeni sia in sistemi di riferimento inerziali che accelerati. L'introduzione della sincronizzazione assoluta implica una modifica delle trasformazioni di Lorentz. Una caratteristica di queste nuove trasformazioni (dette inerziali) è che la trasformazione del tempo è indipendente dalle coordinate spaziali. Le trasformazioni inerziali sono ottenute nel caso generale tra due sistemi di riferimento aventi velocità (assolute) u1 e u2 comunque orientate. Viene mostrato che le trasformazioni inerziali possono formare un gruppo pur di prendere in considerazione anche riferimenti non fisicamente realizzabili perché superluminali. È analizzato il moto rigido secondo Born di un corpo esteso considerando la sincronizzazione assoluta. Sulla base delle trasformazioni inerziali si derivano le trasformazioni per i campi elettromagnetici e le equazioni di questi campi (che sostituiscono le equazioni di Maxwell). Si mostra che queste equazioni contengono soluzioni in assenza di cariche che si propagano nello spazio come onde generalmente anisotrope in accordo con quanto previsto dalle trasformazioni inerziali. L'applicazione di questa teoria elettromagnetica a sistemi accelerati mostra l'esistenza di fenomeni mai osservati che, pur non essendo in contraddizione con la relatività standard, ne forzano l'interpretazione. Viene proposto e descritto un esperimento in cui uno di questi fenomeni è misurabile.

Taylor formula for Kolmogorov equations

After briefly discuss the natural homogeneous Lie group structure induced by Kolmogorov equations in chapter one, we define an intrinsic version of Taylor polynomials and Holder spaces in chapter two. We also compare our definition with others yet known in literature. In chapter three we prove an analogue of Taylor formula, that is an estimate of the remainder in terms of the homogeneous metric.

The coevolution of cooperation and dispersal in social groups and its implications for the emergence of multicellularity

Background Recent work on the complexity of life highlights the roles played by evolutionary forces at different levels of individuality. One of the central puzzles in explaining transitions in individuality for entities ranging from complex cells, to multicellular organisms and societies, is how different autonomous units relinquish control over their functions to others in the group. In addition to the necessity of reducing conflict over effecting specialized tasks, differentiating groups must control the exploitation of the commons, or else be out-competed by more fit groups. Results We propose that two forms of conflict – access to resources within groups and representation in germ line – may be resolved in tandem through individual and group-level selective effects. Specifically, we employ an optimization model to show the conditions under which different within-group social behaviors (cooperators producing a public good or cheaters exploiting the public good) may be selected to disperse, thereby not affecting the commons and functioning as germ line. We find that partial or complete dispersal specialization of cheaters is a general outcome. The propensity for cheaters to disperse is highest with intermediate benefit:cost ratios of cooperative acts and with high relatedness. An examination of a range of real biological systems tends to support our theory, although additional study is required to provide robust tests. Conclusion We suggest that trait linkage between dispersal and cheating should be operative regardless of whether groups ever achieve higher levels of individuality, because individual selection will always tend to increase exploitation, and stronger group structure will tend to increase overall cooperation through kin selected benefits. Cheater specialization as dispersers offers simultaneous solutions to the evolution of cooperation in social groups and the origin of specialization of germ and soma in multicellular organisms.

Groups, information theory, and Einstein's likelihood principle

We propose a unifying picture where the notion of generalized entropy is related to information theory by means of a group-theoretical approach. The group structure comes from the requirement that an entropy be well defined with respect to the composition of independent systems, in the context of a recently proposed generalization of the Shannon-Khinchin axioms. We associate to each member of a large class of entropies a generalized information measure, satisfying the additivity property on a set of independent systems as a consequence of the underlying group law. At the same time, we also show that Einstein's likelihood function naturally emerges as a byproduct of our informational interpretation of (generally nonadditive) entropies. These results confirm the adequacy of composable entropies both in physical and social science contexts.

Clustering of related individuals in a population of the Australian lizard, Egernia frerei

Stable social aggregations are rarely recorded in lizards, but have now been reported from several species in the Australian scincid genus Egernia. Most of those examples come from species using rock crevice refuges that are relatively easy to observe. But for many other Egernia species that occupy different habitats and are more secretive, it is hard to gather the observational data needed to deduce their social structure. Therefore, we used genotypes at six polymorphic microsatellite DNA loci of 229 individuals of Egernia frerei, trapped in 22 sampling sites over 3500 ha of eucalypt forest on Fraser Island, Australia. Each sampling site contained 15 trap locations in a 100 x 50 m grid. We estimated relatedness among pairs of individuals and found that relatedness was higher within than between sites. Relatedness of females within sites was higher than relatedness of males, and was higher than relatedness between males and females. Within sites we found that juvenile lizards were highly related to other juveniles and to adults trapped at the same location, or at adjacent locations, but relatedness decreased with increasing trap separation. We interpreted the results as suggesting high natal philopatry among juvenile lizards and adult females. This result is consistent with stable family group structure previously reported in rock dwelling Egernia species, and suggests that social behaviour in this genus is not habitat driven.

The synthesis of biodegradable polymers using aluminium alkoxide initiators

Alkyl aluminium alkoxides have been used as initiators for the ring opening polymerisation of ε-caprolactone and δ-valerolactone. The effect of the reaction solvent on the kinetics of the polymerisation of ε-caprolactone has been studied. The rate of polymerisation was found to be faster in solvents of lower polarity and donor nature such as toluene. In general solvents of higher polarity resulted in a decreased rate of polymerisation. However solvents such as THF or DMF with a lone pair of electrons capable of forming a complex with the aluminium centre slowed the polymerisation further. The size of the monomer also proved to be an important factor in the kinetics of the reaction. The six membered ring, δ-valerolactone has less ring strain than the seven membered ring ε-caprolactone and thus the polymerisation of δ-valerolactone is slower than the corresponding polymerisation of ε-caprolactone. Both the alkoxide and alkyl group structures have an effect on the polymerisation. In general bulkier alkoxide groups provide greater steric hindrance around the active site at the beginning of the reaction. This causes an induction or a build up period that is related to the both the steric hindrance and also the electronic effects provided by the alkoxide group. The alkyl group structure has an effect throughout the polymerisation because it remains adjacent to the active centre. The number of alkoxide groups on the aluminium centre is also important, using a dialkoxide as an initiator yields polymers with molecular weights approximately half that of the corresponding reactions using a mono alkoxide. Transesterification reactions have also been found to occur after most of the monomer has been consumed. These transesterification reactions are exaggerated as temperature increases. A method of producing tri-block co-polymers has also been developed. A di-hydroxy functional pre-polymer, PHBV, was reacted with an aluminium alkyl to form a di-alkoxide macroinitiator which was subsequently used as an initiator for the polymerisation of ε-caprolactone to form an ABA type tri-block co-polymer. The molecular weight and other properties were predictable from the initial monomer/initiator ratios.

Multiplicative Systems on Ultra-Metric Spaces

AMS Subj. Classification: MSC2010: 42C10, 43A50, 43A75

Sobre la Falsedad y la Inevitabilidad: La Paradoja de la Condición Humana desde el Estudio de los Procesos Migratorios

INTRODUCCIÓN En los últimos tiempos, se percibe en la sociedad una preocupación hacia lo diferente que se manifiesta en procesos discriminatorios y de exclusión. La población y las instituciones manifiestan rechazo al otro-inmigrante con una legislación limitadora de derechos, unos medios de comunicación que alimentan una dinámica discriminadora y excluyente muy peligrosa y, un discurso de la clase política muy negativo para con los inmigrantes. El uso de frases y lemas que generalizan aspectos negativos y conectan la inmigración con el delito, con la amenaza al estado del bienestar y con el desempleo ha de calificarse como peligroso. El primer objetivo de este trabajo es entender a la persona en su paradoja. La paradoja de que somos seres sociales y rechazamos al otro. El segundo objetivo es por un lado, analizar la falsedad de afirmaciones como que “los inmigrantes cometen más delitos que los nacionales o que son más propensos al delito que los nacionales” y, por otro, comprobar que dichas afirmaciones son inevitables. DESARROLLO TEÓRICO En cuanto a la paradoja de que somos seres sociales y rechazamos al otro, se analiza el origen del rechazo al inmigrante desde la naturaleza y la condición humanas, lo que nos lleva a concluir que la percepción de una persona en sociedad se desarrolla en un proceso interrelacional e intersubjetivo que es eminentemente paradójico. La formación de la persona se desarrolla sobre la base del proceso de imitación, la identificación y reidentificación de la persona se exponen en teorías diversas, la teoría de la identidad de la comunidad cuyo máximo representante es Tajfel (1969), la teoría de las creencias de grupo de Bar-Tal (1990), la teoría de la amenaza comprehensiva de Stephan et al. (2005) y la teoría de los valores centrales de Bauman (2001). El segundo objetivo de esta tesis es por un lado, analizar la falsedad de afirmaciones como que “los inmigrantes cometen más delitos que los nacionales o que son más propensos al delito que los nacionales” para lo que se ha realizado una revisión bibliográfica que concluye que los inmigrantes no cometen más delitos que los nacionales y que no son más propensos al delito que los nacionales; y, por otro, comprobar que dichas afirmaciones son inevitables, para lo que se ha aplicado el método estadístico cualitativo teniendo como base la pregunta 18 de la Encuesta del CIS número 2967 del año 2012 relativa a la percepción de la inmigración. Para la comprobación de que dichas afirmaciones son inevitables, se ha aplicado la metodología estadística cualitativa a la pregunta 18 de la Encuesta número 2967 del CIS del año 2012 cuya redacción es la siguiente “La inmigración, como todo, tiene aspectos positivos y negativos. ¿Y qué aspecto negativo destacaría más?” Con la aplicación del método Kendall-Stoyanov se obtuvieron coeficientes de concordancia en el orden de importancia de los items y coeficientes de ponderación que dan mejor información sobre cuán importante es un determinado aspecto negativo sobre los demás. La metodología expuesta se aplicó en dos Análisis fundamentales: un análisis descriptivo y un análisis multivariable. Con el análisis descriptivo se comparan las opiniones de las categorías sociodemográficas propuestas por el CIS. Dado que el análisis descriptivo puede considerarse excesivamente homogéneo y limitado, por cuanto se comparan categorías socio-demográficas que son univariable, se ha procedido a realizar un análisis multivariable comparando dos perfiles. El perfil del cosmopolita responde a las siguientes variables, Hombre o mujer, de 18-40 años, con estudios universitarios e ideología de izquierdas. El perfil provinciano o local responde a estas otras variables, Hombre o mujer, de más de 65 años, con educación básica o secundaria e ideología de derechas. Para numerosos autores (Diez Nicolás, 1999, Cea D´Ancona, 2004, Haubert y Fussel, 2006 y Ford, 2012), los perfiles sociodemográficos muestran que las personas de más de 65 años, de derechas, bajo estatus socioeconómico y baja educación son xenófobos. Por el contrario, la gente joven con alta educación, status socioeconómico alto, de izquierdas y los que han viajado al extranjero muestran menor grado de xenofobia. Sin embargo, tras la aplicación del método Kendall-Stoyanov a la pregunta 18 del CIS, ambos perfiles muestran una absoluta concordancia en cuanto al orden de los aspectos negativos y en cuanto a la importancia atribuida a dichos aspectos. CONCLUSIONES Como primera conclusión, se ha podido constatar lo paradójico de la condición humana. La revisión bibliográfica especializada concluye que los inmigrantes no cometen más delitos que los nacionales y que no son más propensos al delito que los nacionales. Por su parte, con los análisis descriptivo y multivariable, se demuestra la inevitabilidad del rechazo sobre la base de una opinión concordante u homogénea en la sociedad española en el año 2012. Esta homogeneidad se debe, entre otros, al proceso de securitización producido en la sociedad española en 2012. BIBLIOGRAFÍA BAR-TAL, D. (1990). Group Belief: A conception for Analyzing Group Structure, Processes and Behaviour. Springer Science+Business Media. Nueva York. BAUMAN, Z, (2001). “Identity in a Globalizing World”. Social Anthropology, vol. 1, issue 2, pp. 121-129. CEA D ́ANCONA, M.A. (2004). La activación de la xenofobia en España. ¿Qué miden las encuestas? Centro de Investigaciones Sociológicas. Madrid. DÍEZ NICOLÁS, J. (1999). “Los Españoles y la Inmigración”. Ministerio de Trabajo y Asuntos Sociales, Secretaría General de Asuntos Sociales, Instituto de Migraciones y Servicios Sociales. Observatorio Permanente de la Inmigración. FORD, R. (2012). “Parochial and Cosmopolitan Britain. Examining the Social Divide in Reactions to Immigration”. Transatlantic Trends Immigration Focus Papers. HAUBERT, J. and FUSSELL, E. (2006). “Explaining pro-immigrant sentiment in the U.S.: Social class, cosmpolitism, and perceptions of immigrants.” International Migration Review, vol. 40, n. 3. The Center for Migration Studes of Nueva Yor, Inc. pp. 489-507. STEPHAN, W. G., RENFRO, C. L., ESSES, V. M, STEPHAN. C.W. and MATINE, T. (2005). “The effects of feeling threatened on attitudes toward immigrants”. International Journal of Intercultural Relations. Volume 29, Issue 1, Pages 1–19. BAR-TAL, D. TAJFEL, H. (1969). “Cognitive Aspects of Prejudice”, 25 J. SOC. ISSUES 79-97.

Hardware processors for pairing-based cryptography

Bilinear pairings can be used to construct cryptographic systems with very desirable properties. A pairing performs a mapping on members of groups on elliptic and genus 2 hyperelliptic curves to an extension of the finite field on which the curves are defined. The finite fields must, however, be large to ensure adequate security. The complicated group structure of the curves and the expensive field operations result in time consuming computations that are an impediment to the practicality of pairing-based systems. The Tate pairing can be computed efficiently using the ɳT method. Hardware architectures can be used to accelerate the required operations by exploiting the parallelism inherent to the algorithmic and finite field calculations. The Tate pairing can be performed on elliptic curves of characteristic 2 and 3 and on genus 2 hyperelliptic curves of characteristic 2. Curve selection is dependent on several factors including desired computational speed, the area constraints of the target device and the required security level. In this thesis, custom hardware processors for the acceleration of the Tate pairing are presented and implemented on an FPGA. The underlying hardware architectures are designed with care to exploit available parallelism while ensuring resource efficiency. The characteristic 2 elliptic curve processor contains novel units that return a pairing result in a very low number of clock cycles. Despite the more complicated computational algorithm, the speed of the genus 2 processor is comparable. Pairing computation on each of these curves can be appealing in applications with various attributes. A flexible processor that can perform pairing computation on elliptic curves of characteristic 2 and 3 has also been designed. An integrated hardware/software design and verification environment has been developed. This system automates the procedures required for robust processor creation and enables the rapid provision of solutions for a wide range of cryptographic applications.