Circumstellar grain extinction properties of recently discovered post AGB stars

The circumstellar grains of two hot evolved post asymptotic giant branch (post AGB) stars, HD 89353 and HD 213985 were examined. From ultraviolet spectra, energy balance of the flux, and Kurucz models, the extinction around 2175 A was derived. With visual spectra, an attempt was made to detect 6614 A diffuse band absorption arising from the circumstellar grains so that we could examine the relationship of these features to the infrared features. For both stars, we did not detect any diffuse band absorption at 6614 A, implying the carrier of this diffuse band is not the carrier of the unidentified infrared features not of the 2175 A bump. The linear ultraviolet extinction of the carbon-rich star HD 89353 was determined to continue across the 2175 A region with no sign of the bump; for HD 213985 it was found to be the reverse: a strong, wide bump in the mid-ultraviolet. The 213985 bump was found to be positioned at 2340 A, longward of its usual position in the interstellar medium. Since HD 213985 was determined to have excess carbon, the bump probably arises from a carbonaceous grain. Thus, in view of the ultraviolet and infrared properties of the two post AGB stars, ubiquitous interstellar infrared emission features do not seem to be associated with the 2175 A bump. Instead, the infrared features seem related to the linear ultraviolet extinction component: hydrocarbon grains of radius less than 300 A are present with the linear HD 89353 extinction; amorphous anhydrous carbonaceous grains of radius less than 50 A might cause the shifted ultraviolet extinction bump of HD 213985

Emissões de metano e óxido nitroso em sistemas de cultivo em terras baixas sob diferentes manejos de água, do solo e da cobertura vegetal.

O sistema de irrigação, as práticas de manejo da água e manejos diferenciados de preparo do solo para o cultivo do arroz são fatores determinantes à produção deste cereal, influenciando de forma diferenciada o efluxo de gases de efeito estufa (GEE), sendo que alguns desses apresentam potencial mitigador das emissões de GEE. Três estudos foram conduzidos visando avaliar: (I) as condições de oxirredução do solo e a influência de manejos de água sobre as emissões de metano (CH4) e óxido nitroso (N2O) (GEE) em solo cultivado com arroz (Estudo I); (II) avaliar a influência de dois sistemas de irrigação (Inundação e Aspersão) sobre as emissões de CH4 e N2O em solo cultivado com arroz, sendo essas emissões comparadas com uma área natural (Estudo II) e, (III) avaliar a influência da época e das operações de preparo do solo e da cobertura vegetal sobre as emissões anuais de CH4 e N2O do solo, bem como a contribuição desses gases para o potencial de aquecimento global parcial (PAGp) em sistema de produção de grãos em terras baixas e, com isso, definir práticas de manejo e sistemas de cultivos com potencial mitigador de emissões de GEE em terras baixas (Estudo III). Os estudos foram conduzidos de novembro de 2011 até abril de 2015, em um Planossolo no Sul do Brasil. Na maior parte do período as avaliações de CH4 e N2O foram realizadas semanalmente, utilizando-se o método da câmara fechada estática. Com base nas emissões de CH4 e de N2O e dos seus respectivos potenciais de aquecimento global (PAG; 25 e 298), foi calculado o PAGp (PAGp; CO2 equivalente). Foram avaliados também o volume de água aplicado e a produtividade de grãos (PG), possibilitando a obtenção dos índices de eficiência do uso de água (EUA) e PAGp/PG. No Estudo I foram avaliados os tratamentos nas safras 2011/12 e 2012/13: Inundação Contínua (IC); Inundação Contínua por Período Reduzido (PR); Inundação Intermitente (II); Solo Saturado (SS). Nas duas safras avaliadas, nos manejos da irrigação II e SS, a redução das emissões de CH4 foi superior ao efeito no aumento nas emissões de N2O, ou seja, apresentaram o menor PAGp, mostrando-se mais eficientes na mitigação de GEE em relação aos outros dois tratamentos, IC e PR. No Estudo II - foram avaliados por dois anos completos (duas Safras e duas Entressafras) os tratamentos: Sistema de Irrigação por Inundação; Sistema de Irrigação por Aspersão; Área Natural: área em condição natural, ou seja, sem histórico de cultivo. Apesar do sistema de irrigação por aspersão potencializar as emissões de N2O do solo, ainda assim, é mais eficiente na redução do PAGp em relação ao sistema irrigado por alagamento do solo em cultivos de arroz. No Estudo III - foram avaliados por dois anos completos (duas Safras e duas Entressafras) quatro sistemas de cultivo: T1 ? Arroz/soja/arroz; T2 ?Arroz/Arroz/Arroz; T3 ? Arroz/Arroz/Soja; T4 ? Arroz/Soja/Arroz c/ preparo. O N2O é o principal componente do potencial de aquecimento global da soja, enquanto que o CH4 predomina no cultivo de arroz irrigado.Tese (Doutorado em Ciências) - Programa de pós-graduação em Agronomia, área de concentração: Solos. Universidade Federal de Pelotas, Pelotas. Orientador: Rogério Oliveira de Sousa. Coorientadora: Wallkyria Bueno Scivittaro (CPACT)

Towards Verifying Nonlinear Integer Arithmetic

We eliminate a key roadblock to efficient verification of nonlinear integer arithmetic using CDCL SAT solvers, by showing how to construct short resolution proofs for many properties of the most widely used multiplier circuits. Such short proofs were conjectured not to exist. More precisely, we give n^{O(1)} size regular resolution proofs for arbitrary degree 2 identities on array, diagonal, and Booth multipliers and quasipolynomial- n^{O(\log n)} size proofs for these identities on Wallace tree multipliers.Comment: Expanded and simplified with improved result

Disgust and Mating Strategy

Cataloged from PDF version of article.An evolutionary task analysis predicts a connection between disgust and human mating, two important but currently disconnected areas of psychology. Because short-term mating strategies involve sex with multiple partners after brief temporal durations, such a strategy should be difficult to pursue in conjunction with high levels of sexual disgust. On this basis, we hypothesized that individuals with a stronger proclivity for short-term mating would exhibit dispositionally lower levels of sexual disgust. Two independent studies provided strong support for this hypothesis: among both men and women, an orientation toward short-term mating was associated with reduced levels of sexual disgust, but not with suppressed moral or pathogen disgust. Our discussion highlights an unexpected finding and suggests important questions for future research. © 2015 Elsevier Inc

Limitations of Algebraic Approaches to Graph Isomorphism Testing

We investigate the power of graph isomorphism algorithms based on algebraic reasoning techniques like Gr\"obner basis computation. The idea of these algorithms is to encode two graphs into a system of equations that are satisfiable if and only if if the graphs are isomorphic, and then to (try to) decide satisfiability of the system using, for example, the Gr\"obner basis algorithm. In some cases this can be done in polynomial time, in particular, if the equations admit a bounded degree refutation in an algebraic proof systems such as Nullstellensatz or polynomial calculus. We prove linear lower bounds on the polynomial calculus degree over all fields of characteristic different from 2 and also linear lower bounds for the degree of Positivstellensatz calculus derivations. We compare this approach to recently studied linear and semidefinite programming approaches to isomorphism testing, which are known to be related to the combinatorial Weisfeiler-Lehman algorithm. We exactly characterise the power of the Weisfeiler-Lehman algorithm in terms of an algebraic proof system that lies between degree-k Nullstellensatz and degree-k polynomial calculus

The weakness of diffuse bands in nebular environments. Possible impact on thePAH+ hypothesis

It has been widely suggested that PAH cations (PAH+) may be the carriers of the diffuse interstellar bands, so it is of interest to probe diffuse behavior in regions suspected of having high abundances of PAHs. Here we examine the strengths of several of the visible-wavelength diffuse interstellar bands in two nebular environments where infrared emission and ultraviolet indicators show that PAHs are abundant. One might expect the PAHs to be predominantly positively ionized in these regions, yet the diffuse bands are systematically weak. This led us to examine the ionization balance for see whether the weakness of the diffuse bands might rule out PAH cations as the carriers. We find that this conclusion is ambiguous, however, due to the very rapid rates for recombination of PAHs: under conditions that may reasonably represent our observed nebulae, the PAHs might be in predominantly neutral form. If so, this would explain the weakness of the diffuse bands, but leaves open some very perplexing questions about where the PAHs might be dominantly in cation form, hence where the diffuse bands do arise if they are due to PAH+

The weakness of diffuse bands in nebular environments. Possible impact on thePAH+ hypothesis

It has been widely suggested that PAH cations (PAH+) may be the carriers of the diffuse interstellar bands, so it is of interest to probe diffuse behavior in regions suspected of having high abundances of PAHs. Here we examine the strengths of several of the visible-wavelength diffuse interstellar bands in two nebular environments where infrared emission and ultraviolet indicators show that PAHs are abundant. One might expect the PAHs to be predominantly positively ionized in these regions, yet the diffuse bands are systematically weak. This led us to examine the ionization balance for see whether the weakness of the diffuse bands might rule out PAH cations as the carriers. We find that this conclusion is ambiguous, however, due to the very rapid rates for recombination of PAHs: under conditions that may reasonably represent our observed nebulae, the PAHs might be in predominantly neutral form. If so, this would explain the weakness of the diffuse bands, but leaves open some very perplexing questions about where the PAHs might be dominantly in cation form, hence where the diffuse bands do arise if they are due to PAH+

Good Mates Retain Us Right: Investigating the Relationship between Mate Retention Strategies, Mate Value and Relationship Satisfaction

Mate retention strategies are an important tool in keeping a partner, and their use is determined by the mate value (MV) of the partner one is trying to keep. The type of strategy used is also dependent on one’s own MV: mates of lower MV are more prone to exhibiting strategies that are cost-inflicting for their partners, whereas partner-benefiting strategies are used by mates of higher value. The type of strategies used affects relationship satisfaction (RS), and is also affected by the perceived difference in MVs. However, it is unclear how someone’s perception of their partner’s MV is related to that partner’s behavior and their own RS. To this aim, we investigated the relationship between these variables on a sample of 178 couples. Our results showed that benefit-inducing strategies were used more by—and towards—partners of higher MV, and were positively connected with RS. Cost-inflicting strategies were more used by—and towards—partners of lower MV, and were negatively connected with RS. Less MV difference was positively correlated with RS and benefiting strategies, and negatively correlated with cost-inflicting strategies. It seems that good mates use strategies that benefit their partners, which, in turn, make them more valuable and, consequently, their partner more satisfied

Division of labour and the evolution of multicellularity

Understanding the emergence and evolution of multicellularity and cellular differentiation is a core problem in biology. We develop a quantitative model that shows that a multicellular form emerges from genetically identical unicellular ancestors when the compartmentalization of poorly compatible physiological processes into component cells of an aggregate produces a fitness advantage. This division of labour between the cells in the aggregate occurs spontaneously at the regulatory level due to mechanisms present in unicellular ancestors and does not require any genetic pre-disposition for a particular role in the aggregate or any orchestrated cooperative behaviour of aggregate cells. Mathematically, aggregation implies an increase in the dimensionality of phenotype space that generates a fitness landscape with new fitness maxima, and in which the unicellular states of optimized metabolism become fitness saddle points. Evolution of multicellularity is modeled as evolution of a hereditary parameter, the propensity of cells to stick together, which determines the fraction of time a cell spends in the aggregate form. Stickiness can increase evolutionarily due to the fitness advantage generated by the division of labour between cells in an aggregate.Comment: 28 pages, 2 figure