Towards improved 1-D settler modelling : calibration of the Bürger model and case study

Recently, Burger et al. (2011) developed a new 1-D SST model which allows for more realistic predictions of the sludge settling behaviour than traditional 1-D models used to date. However, the addition of a compression function in this new 1-D model complicates the model calibration. This study aims to report advances in the calibration of this novel 1-D model. Data of the evolution of the sludge blanket height during batch settling experiments were collected at different initial solids concentrations. Based on the linear slopes of the batch settling curves the hindered settling velocity functions by Vesilind (1968) and Takacs et al. (1991) were calibrated. Although both settling velocity functions gave a good fit to the experimental data, very large confidence intervals were found for the parameters of the settling velocity by Takacs. Global sensitivity analysis showed that it is not possible to find a unique set of parameter values for the settling function by Takacs based on experimental data of the hindered settling velocity. Subsequently, the calibrated Vesilind settling velocity was implemented in the 1-D model by Burger et al. (2011) and the parameters of the additional compression function were calibrated by fitting the model by Burger et al. (2011) to the batch settling curves. Simulation results showed that while the 1-D model by Takacs et al. (1991) underpredicted the experimental data of sludge blanket heights, the model by Burger et al. (2011) was able to predict the experimental data far more accurately. However, a global sensitivity analysis showed that no unique optimum for the combined set of hindered and compression parameters could be found

Richness of Termites and Ants in the State of Rio Grande do Sul, Southern Brazil

Previous studies on the effects of environmental factors, such as altitude, latitude, temperature, deforestation, forest fragmentation, fire, and flood on the community structure of termites and ants were conducted in various regions of Brazil; few of them were carried out in the southernmost Brazilian state of Rio Grande do Sul. Here we describe termites and ants diversity at different sites along the four geomorphologic units of this state. We recorded 16 taxa of termites, of which three are new state records, increasing to 19 the number of termite species known to occur in the state. Accordingly, we also found 73 species and 115 morphospecies of ants, of which only one was a new record, raising to 265 taxa the number of ant species known to occur in the state. As expected, we found a higher species richness of ants than termites. The low richness of both groups relative to other Brazilian regions could be a consequence of the subtropical to temperate climate in the state, since most portions of the state are below 30o latitude, the study areas be above 500 m altitude, and other environmental characteristics of each site. We suggest a positive relationship between species richness of termites and altitude, while ant richness indicated an inverse relationship. However, our data are not conclusive, due to the low number of replications in each altitude, particularly for termites. This study is unique in presenting an updated checklist of termites and ants in the state of Rio Grande do Sul

Interações entre formigas atendentes, afídeos dos cítricos e joaninhas em plantas de Citrus sinensis

Attending ants promote colony survivorship and reproduction of aphid colonies, mainly by protection against natural enemies. However, very few papers are about the assessment of the effect of attending ants directly on individuals of aphids without the presence of other organisms. In this article, a review of the main papers that had assessed the effect of the attendant ant Camponotus punctulatus (Formicidae) on the table of life of the brown-citrusaphid Toxoptera citricidus (Hemiptera: Aphididae) that grows in plants of Citrus sinensis (Rutaceae) without the presence of natural enemies. The ant behavior in the presence of adults and immature individuals of the ladybug Cycloneda sanguinea (Coleoptera: Coccinellidae) in colonies kept on Poncirus trifoliata was also evaluated. Nymph survivorship, adult total fertility, reproductive and post-reproductive period were not affected by the attending ants. The elevation of mean and daily fecundity of the aphids attending on the first days has great importance in the population growth. Ant behavior does not depend on the ladybug sex, nor on the colony size, so that ladybug larvae are more tolerated than adults in the aphid colonies. We registered that the behaviour of the aphids is similar independently of their sex and colony size, whereas ladybug larvae are more tolerated than their adults in aphid colonies.Keywords: survivorship, fecundity, table of life, population growth.As formigas atendentes aumentam a sobrevivência e a reprodução das colônias de afídeos, principalmente pela proteção contra os inimigos naturais. Entretanto, são raros os trabalhos que avaliam o efeito das formigas atendentes diretamente sobre os indivíduos sem a presença de outros organismos. Neste artigo, é feita uma revisão dos principais trabalhos que avaliaram o efeito da formiga atendente Camponotus punctulatus (Formicidae) sobre o pulgão Toxoptera citricidus (Hemiptera: Aphididae) mantido em plantas de Citrus sinensis (Rutaceae) na ausência de inimigos naturais. Também foi avaliado o comportamento dessas formigas na presença de adultos e imaturos de Cycloneda sanguinea (Coleoptera: Coccinellidae) em plantas de Poncirus trifoliata. O aumento da fecundidade média e diária de pulgões atendidos nos primeiros dias tem papel importante no crescimento populacional. Neste trabalho, observamos que o comportamento dos afídeos (T. citricidus) é semelhante independentemente do seu sexo e do tamanho das colônias de formigas (C. punctulatus), sendo que as larvas de joaninhas (C. sanguinea) são mais toleradas do que os adultos das joaninhas nas colônias de pulgões.Palavras-chave: sobrevivência, fecundidade, tabela de vida, crescimento populacional

Isoenzyme variation in the leaf-cutting ants Acromyrmex heyeri and Acromyrmex striatus (Hymenoptera, formicidae)

This is the first study of isoenzyme variability in the leaf-cutting ants (Myrmicinae, Attini) Acromyrmex heyeri (Forel, 1899) and A. striatus (Roger, 1863) which are common throughout the southern Brazilian state of Rio Grande do Sul. We studied the alloenzyme variability of malate dehydrogenase (MDH), alpha-glycerophosphate dehydrogenase (alpha-GPDH) and amylase (AMY) in 97 colonies of A. heyeri and 103 colonies of A. striatus. Five loci were found for these enzyme systems, one locus (Amy-1) being monomorphic in both species and four loci (Mdh-1, alpha-Gpdh-1, Amy-2, and Amy-4) being polymorphic. For each species there were exclusive alleles for the Mdh-1 and Amy-2 loci and differences were also found in the allele frequencies for the other polymorphic loci. Ontogenetically different gene activity was detected for the MDH and alpha-GPDH systems, with between-caste differences, probably related to flight activity, also being found for alpha-GPDH

Table S-1

Previous studies on the effects of environmental factors, such as altitude, latitude, temperature, deforestation, forest fragmentation, fire, and flood on the community structure of termites and ants were conducted in various regions of Brazil; few of them were carried out in the southernmost Brazilian state of Rio Grande do Sul. Here we describe termites and ants diversity at different sites along the four geomorphologic units of this state. We recorded 16 taxa of termites, of which three are new state records, increasing to 19 the number of termite species known to occur in the state. Accordingly, we also found 73 species and 115 morphospecies of ants, of which only one was a new record, raising to 265 taxa the number of ant species known to occur in the state. As expected, we found a higher species richness of ants than termites. The low richness of both groups relative to other Brazilian regions could be a consequence of the subtropical to temperate climate in the state, since most portions of the state are below 30o latitude, the study areas be above 500 m altitude, and other environmental characteristics of each site. We suggest a positive relationship between species richness of termites and altitude, while ant richness indicated an inverse relationship. However, our data are not conclusive, due to the low number of replications in each altitude, particularly for termites. This study is unique in presenting an updated checklist of termites and ants in the state of Rio Grande do Sul.</p

Forward–backward SDEs with distributional coefficients

Forward–backward stochastic differential equations (FBSDEs) have attracted significant attention since they were introduced, due to their wide range of applications, from solving non-linear PDEs to pricing American-type options. Here, we consider two new classes of multidimensional FBSDEs with distributional coefficients (elements of a Sobolev space with negative order). We introduce a suitable notion of solution and show its existence and in certain cases its uniqueness. Moreover we establish a link with PDE theory via a non-linear Feynman–Kac formula. The associated semi-linear parabolic PDE is the same for both FBSDEs, also involves distributional coefficients and has not previously been investigated

GRIPS - Gamma-Ray Imaging, Polarimetry and Spectroscopy

We propose to perform a continuously scanning all-sky survey from 200 keV to 80 MeV achieving a sensitivity which is better by a factor of 40 or more compared to the previous missions in this energy range. The Gamma-Ray Imaging, Polarimetry and Spectroscopy (GRIPS) mission addresses fundamental questions in ESA's Cosmic Vision plan. Among the major themes of the strategic plan, GRIPS has its focus on the evolving, violent Universe, exploring a unique energy window. We propose to investigate $\gamma$-ray bursts and blazars, the mechanisms behind supernova explosions, nucleosynthesis and spallation, the enigmatic origin of positrons in our Galaxy, and the nature of radiation processes and particle acceleration in extreme cosmic sources including pulsars and magnetars. The natural energy scale for these non-thermal processes is of the order of MeV. Although they can be partially and indirectly studied using other methods, only the proposed GRIPS measurements will provide direct access to their primary photons. GRIPS will be a driver for the study of transient sources in the era of neutrino and gravitational wave observatories such as IceCUBE and LISA, establishing a new type of diagnostics in relativistic and nuclear astrophysics. This will support extrapolations to investigate star formation, galaxy evolution, and black hole formation at high redshifts.Comment: to appear in Exp. Astron., special vol. on M3-Call of ESA's Cosmic Vision 2010; 25 p., 25 figs; see also www.grips-mission.e