Maternal effects on offspring size and packaging constraints in the whelk

Life-history theory predicts an optimal offspring size, irrespective of reproductive effort; however, in some species offspring size correlates positively with maternal size. We examine hypotheses for why this latter situation should occur in the whelk Buccinum undatum. The trade-offs between aspects of reproduction in whelks are complicated due to the provision of protective egg capsules. Many eggs are placed within each capsule but c. 99% of these eggs are consumed by the remaining developing young. Large maternal size results in more eggs, larger eggs, more eggs consumed per hatchling, more capsules, larger capsules, more eggs per capsule, a larger number of hatchlings per capsule and larger hatchlings. Increased intra-capsule and post-hatch sibling competition may decrease the marginal value for additional young and select for larger young, however, our data do not support this explanation. Instead, packaging constraints within each capsule limit the size of hatchlings but this constraint is relaxed for medium to large females because they produce large capsules. Small females appear to produce young below optimum size because of the space constraint thus explaining the correlation between maternal size and offspring size.

Effect of batch size on mechanical properties of granules in high shear granulation

The flow patterns in a high shear granulator depend on the fill volume. For example, DEM simulations reported by Terashita et al. [1] show that fill volume affects the velocities and kinetic energies of the particles. It also influences the granule size distribution [2]. Here the effects on the properties of the granule are described. The total mass of the granulate material was varied without changing the other variables such as impeller speed, granulation time and liquid to solid ratio. The resulting mechanical properties, such as strength, yield stress and Young's modulus, of the granules were measured. For the materials studied in the current work, increasing the fill factor (batch size) increased the values of these material parameters. This could be explained by the relative increase in the number and intensity of collisions between the particles, when the size of a batch was increased, leading to smaller porosities. (c) 2010 Elsevier B.V. All rights reserved.

Genome-wide association of early-onset myocardial infarction with single nucleotide polymorphisms and copy number variants

We conducted a genome-wide association study testing single nucleotide polymorphisms (SNPs) and copy number variants (CNVs) for association with early-onset myocardial infarction in 2,967 cases and 3,075 controls. We carried out replication in an independent sample with an effective sample size of up to 19,492. SNPs at nine loci reached genome-wide significance: three are newly identified (21q22 near MRPS6-SLC5A3-KCNE2, 6p24 in PHACTR1 and 2q33 in WDR12) and six replicated prior observations1-4 (9p21, 1p13 near CELSR2-PSRC1-SORT1, 10q11 near CXCL12, 1q41 in MIA3, 19p13 near LDLR and 1p32 near PCSK9). We tested 554 common copy number polymorphisms (>1% allele frequency) and none met the pre-specified threshold for replication (P < 10-3). We identified 8,065 rare CNVs but did not detect a greater CNV burden in cases compared to controls, in genes compared to the genome as a whole, or at any individual locus. SNPs at nine loci were reproducibly associated with myocardial infarction, but tests of common and rare CNVs failed to identify additional associations with myocardial infarction risk.

The size distribution of Jupiter Family comet nuclei

We present an updated cumulative size distribution (CSD) for Jupiter Family comet (JFC) nuclei, including a rigorous assessment of the uncertainty on the slope of the CSD. The CSD is expressed as a power law, N(>rN) ?r-qN, where rN is the radius of the nuclei and q is the slope. We include a large number of optical observations published by us and others since the comprehensive review in the Comets II book, and make use of an improved fitting method. We assess the uncertainty on the CSD due to all of the unknowns and uncertainties involved (photometric uncertainty, assumed phase function, albedo and shape of the nucleus) by means of Monte Carlo simulations. In order to do this we also briefly review the current measurements of these parameters for JFCs. Our final CSD has a slope q= 1.92 ± 0.20 for nuclei with radius rN= 1.25 km.

Fasciola hepatica: Comparative effects of host resistance and parasite intra-specific interactions on size and reproductive histology in flukes from rats infected with isolates differing in triclabendazole sensitivity

The efficacies of putative fasciolicides and vaccines against Fasciola hepatica are frequently monitored in clinical and field trials by determination of fluke egg output in host faeces and by worm counts in the host liver at autopsy. Less often used are parameters based on fluke size and histology, yet these can provide important indications of specific effects on the development of particular germ-line or somatic tissues, especially in relation to the timing and profligacy of egg production. In this study. F. hepatica metacercariae of two distinct isolates, the triclabendazole (TCBZ)-sensitive Cullompton isolate and the TCBZ-resistant Oberon isolate, were administered to rats as single-isolate or mixed-isolate infections. At autopsy 16 weeks later individual adult flukes were counted, measured and the reproductive organs were examined histologically. The degree of development of the testis tubules in each fluke was represented by a numerical score, based on the proportion of the histological section profiles occupied by testis tissue. The level of anti-F. hepatica antibody in the serum of each rat was determined by ELISA. It was found that Cullompton flukes were significantly larger than Oberon flukes, and that significantly more Cullompton metacercariae developed to adults than Oberon metacercariae. The Cullompton flukes showed histological evidence of aspermy and spermatogenic arrest, which was reflected in quantitatively reduced testicular development, as compared with the Oberon isolate. In Cullompton flukes, parthenogenetic egg development is implied. The size of Cullompton and Oberon flukes was significantly related to the number of adult flukes recovered, to the number of metacercariae administered, and to the percentage success of infection. The testis development score in both isolates was significantly related to the number of adult flukes recovered but not to the number of metacercariae administered, or to the percentage success of infection. Fluke size was positively related to testis score for both isolates, and a significant negative relationship was found between percentage success of infection and metacercarial dose. The results are interpreted in terms of differing interactions between various numbers of young flukes and host immunity during invasion of and migration in the hepatic parenchyma, and of fluke intra-specific (possibly pheromonal) stimulatory effects in the final stages of development, within the host bile ducts. No significant relationships were found between host antibody levels and fluke size or testis score. False positive serological reactions were found in some rats that had been infected, but found to harbour no flukes at autopsy. Clearly the act of eliminating the flukes involved generation of an immune response. (C) 2011 Elsevier B.V. All rights reserved.

Droplet size control with methanol-repellent surface in a sampling device for continuous annular electrochromatography

The eluent droplet size defines the number of sampling compartments in a continuously operated annular electrochromatograph and therefore influences separation efficiency. In this work, an assembly of two capillaries, a feeding capillary on the top and a receiving capillary placed under it, has been investigated to control droplet size. The receiving capillary prevents the liquid droplet formation beyond a critical size, which reduces the volume of sampling compartment as compared with the case of the electrolyte flow driven solely by gravity. With a receiving capillary, the electrolyte droplet size was reduced from 1.5 to 0.46 mm. Further decrease of droplet size was not possible due to a so-called droplet jump upwards effect which has been observed on a hydrophilic glass surface with water. A typical electrolyte used in CAEC has high methanol content. In an attempt to improve the methanol-repellent properties of the glass surface, two approaches have been implemented: (i) self-assembled chemisorbed monolayers of an alkylsiloxane and (ii) fabrication of a nano-pin film. The methanol-repellent surface of the feeding capillary suppressed the droplet jump upwards effect. The surface remained methanol repellent in different solutions with lower polarity than that of water.

Why the size structure of marine communities can require decades to recover from fishing

A dynamic food-web model of more than 1000 species was used to quantify the recovery trajectory of marine community size-structure under different hypothetical fishing regimes, using the Northeast Atlantic as an example. Size-structure was summarised by four indicators: the Large Fish Indicator (LFI), the Large Species Indicator (LSI), the biomass-weighted mean maximum length of fish species (EMBED Equation.3) and the biomass-weighted mean maturation length of fish species (EMBED Equation.3). Time-series of these indicators recorded recovery following release from fishing with various size-selectivities, intensities and durations. In model simulations, fishing-induced trophic cascades were observed to distort fish community size-structure, but these did not have a large influence on recovery level or duration as measured by the four indicators. However, simulations showed that local extinctions of large fish species increased in number with both fishing intensity and duration, and could strongly limit the recovery level. Recovery of fish community size-structure to near equilibrium frequently took multiple decades in simulations; these long transient periods suggest that management interventions for size-structure recovery may require much longer than previously thought. Our results demonstrate the need for community-level modelling to set realistic targets for management of community size-structure.

The welfare implications of large litter size in the domestic pig I:Biologica factors

Increasing litter size has long been a goal of pig breeders and producers, and may have implications for pig (Sus scrofa domesticus) welfare. This paper reviews the scientific evidence on biological factors affecting sow and piglet welfare in relation to large litter size. It is concluded that, in a number of ways, large litter size is a risk factor for decreased animal welfare in pig production. Increased litter size is associated with increased piglet mortality, which is likely to be associated with significant negative animal welfare impacts. In surviving piglets, many of the causes of mortality can also occur in non-lethal forms that cause suffering. Intense teat competition may increase the likelihood that some piglets do not gain adequate access to milk, causing starvation in the short term and possibly long-term detriments to health. Also, increased litter size leads to more piglets with low birth weight which is associated with a variety of negative long-term effects. Finally, increased production pressure placed on sows bearing large litters may produce health and welfare concerns for the sow. However, possible biological approaches to mitigating health and welfare issues associated with large litters are being implemented. An important mitigation strategy is genetic selection encompassing traits that promote piglet survival, vitality and growth. Sow nutrition and the minimisation of stress during gestation could also contribute to improving outcomes in terms of piglet welfare. Awareness of the possible negative welfare consequences of large litter size in pigs should lead to further active measures being taken to mitigate the mentioned effects. © 2013 Universities Federation for Animal Welfare.

A generalization of the Hoffman-Lovász upper bound on the independence number of a regular graph

A family of quadratic programming problems whose optimal values are upper bounds on the independence number of a graph is introduced. Among this family, the quadratic programming problem which gives the best upper bound is identified. Also the proof that the upper bound introduced by Hoffman and Lovász for regular graphs is a particular case of this family is given. In addition, some new results characterizing the class of graphs for which the independence number attains the optimal value of the above best upper bound are given. Finally a polynomial-time algorithm for approximating the size of the maximum independent set of an arbitrary graph is described and the computational experiments carried out on 36 DIMACS clique benchmark instances are reported.

Estimating the size of the population of persons who inject drugs in the island of Montréal, Canada, using a six-source capture-recapture model

BACKGROUND: To plan and implement services to persons who inject drugs (PWID), knowing their number is essential. For the island of Montréal, Canada, the only estimate, of 11,700 PWID, was obtained in 1996 through a capture-recapture method. Thirteen years later, this study was undertaken to produce a new estimate. METHODS: PWID were defined as individuals aged 14-65 years, having injected recently and living on the island of Montréal. The study period was 07/01/2009 to 06/30/2010. An estimate was produced using a six-source capture-recapture log-linear regression method. The data sources were two epidemiological studies and four drug dependence treatment centres. Model selection was conducted in two steps, the first focusing on interactions between sources and the second, on age group and gender as covariates and as modulators of interactions. RESULTS: A total of 1480 PWID were identified in the six capture sources. They corresponded to 1132 different individuals. Based on the best-fitting model, which included age group and sex as covariates and six two-source interactions (some modulated by age), the estimated population was 3910 PWID (95% confidence intervals (CI): 3180-4900) which represents a prevalence of 2.8 (95% CI: 2.3-3.5) PWID per 1000 persons aged 14-65 years. CONCLUSIONS: The 2009-2010 estimate represents a two-third reduction compared to the one for 1996. The multisource capture-recapture method is useful to produce estimates of the size of the PWID population. It is of particular interest when conducted at regular intervals thus allowing for close monitoring of the injection phenomenon.

On the choice of posittioning and cluster size for fixed relay stations in a LTE network

The long term evolution (LTE) is one of the latest standards in the mobile communications market. To achieve its performance, LTE networks use several techniques, such as multi-carrier technique, multiple-input-multiple-output and cooperative communications. Inside cooperative communications, this paper focuses on the fixed relaying technique, presenting a way for determining the best position to deploy the relay station (RS), from a set of empirical good solutions, and also to quantify the associated performance gain using different cluster size configurations. The best RS position was obtained through realistic simulations, which set it as the middle of the cell's circumference arc. Additionally, it also confirmed that network's performance is improved when the number of RSs is increased. It was possible to conclude that, for each deployed RS, the percentage of area served by an RS increases about 10 %. Furthermore, the mean data rate in the cell has been increased by approximately 60 % through the use of RSs. Finally, a given scenario with a larger number of RSs, can experience the same performance as an equivalent scenario without RSs, but with higher reuse distance. This conduces to a compromise solution between RS installation and cluster size, in order to maximize capacity, as well as performance.

Quantitative analysis of postnatal neurogenesis and neuron number in the macaque monkey dentate gyrus

The dentate gyrus is one of only two regions of the mammalian brain where substantial neurogenesis occurs postnatally. However, detailed quantitative information about the postnatal structural maturation of the primate dentate gyrus is meager. We performed design-based, stereological studies of neuron number and size, and volume of the dentate gyrus layers in rhesus macaque monkeys (Macaca mulatta) of different postnatal ages. We found that about 40% of the total number of granule cells observed in mature 5-10-year-old macaque monkeys are added to the granule cell layer postnatally; 25% of these neurons are added within the first three postnatal months. Accordingly, cell proliferation and neurogenesis within the dentate gyrus peak within the first 3 months after birth and remain at an intermediate level between 3 months and at least 1 year of age. Although granule cell bodies undergo their largest increase in size during the first year of life, cell size and the volume of the three layers of the dentate gyrus (i.e. the molecular, granule cell and polymorphic layers) continue to increase beyond 1 year of age. Moreover, the different layers of the dentate gyrus exhibit distinct volumetric changes during postnatal development. Finally, we observe significant levels of cell proliferation, neurogenesis and cell death in the context of an overall stable number of granule cells in mature 5-10-year-old monkeys. These data identify an extended developmental period during which neurogenesis might be modulated to significantly impact the structure and function of the dentate gyrus in adulthood.

On the efficient evaluation of ruin probabilities for completely monotone claim size distributions

In this paper we propose a highly accurate approximation procedure for ruin probabilities in the classical collective risk model, which is based on a quadrature/rational approximation procedure proposed in [2]. For a certain class of claim size distributions (which contains the completely monotone distributions) we give a theoretical justification for the method. We also show that under weaker assumptions on the claim size distribution, the method may still perform reasonably well in some cases. This in particular provides an efficient alternative to a related method proposed in [3]. A number of numerical illustrations for the performance of this procedure is provided for both completely monotone and other types of random variables.

Size regulation of double and half embryos in the mice musculus

Genetic chimeras made by aggregating early mouse embryos have many uses in developmental biology and have also provided insights into embryonic growth regulation. There is an indication that the embryo can regulate for an increase in size because although aggregation chimeras are twice as big as normal embryos when made, they are born of normal size. Upward regula..... tion of size reduced embryos is also possible. Half embryos made by the isolation or destruction of one of the blastomeres of a 2-cell embryo are also born of normal size. Little is known about the timing or the mechanism of this size regulation. In this study, the timing of size regulation in double and half embryos was clearly established by comparison of cell numbers derived from serial reconstruction of light microscope sections of control and experimental embryos. It was shown that size regulation in double embryos occurred around 6dl6h and in half embryos by 7dOh. Size regulation occurred in all tissues at the same time indicating a single control mechanism for the entire embryo. More detailed examination of the growth of double embryos revealed that size regulation occurred by alteration in cell cycle length~ No excessive cell death was found in double embryos compared to the controls and continuous labelling with [3H] thymidine showed no large non-dividing cell population in double embryos. However, a comparison of the mitotic index of double and control embryos after colcemid treatment, revealed a large difference between the two around 5dl6h to 6d16h. During this period, control embryos underwent a proliferative burst not shown by the double embryos. The mechanism for cell cycle control is not clear; it may be intrinsic to the embryo or determined by the uterine environment. Evidence was found suggesting that differentiation in the postimplantation embryo was cell number dependent. The timing of differentiative events was examined in half, double and control embryos. Proamnion formation, which occurs prior to size regulation, occurs at the same cell number but at different times in the three groups of embryos. However mesoderm which appears after size regulation was seen at the same time in all grollps of embryos.

On some Density Theorems in Number Theory and Group Theory

Gowers, dans son article sur les matrices quasi-aléatoires, étudie la question, posée par Babai et Sos, de l'existence d'une constante $c>0$ telle que tout groupe fini possède un sous-ensemble sans produit de taille supérieure ou égale a $c|G|$. En prouvant que, pour tout nombre premier $p$ assez grand, le groupe $PSL_2(\mathbb{F}_p)$ (d'ordre noté $n$) ne posséde aucun sous-ensemble sans produit de taille $c n^{8/9}$, il y répond par la négative. Nous allons considérer le probléme dans le cas des groupes compacts finis, et plus particuliérement des groupes profinis $SL_k(\mathbb{Z}_p)$ et $Sp_{2k}(\mathbb{Z}_p)$. La premiére partie de cette thése est dédiée à l'obtention de bornes inférieures et supérieures exponentielles pour la mesure suprémale des ensembles sans produit. La preuve nécessite d'établir préalablement une borne inférieure sur la dimension des représentations non-triviales des groupes finis $SL_k(\mathbb{Z}/(p^n\mathbb{Z}))$ et $Sp_{2k}(\mathbb{Z}/(p^n\mathbb{Z}))$. Notre théoréme prolonge le travail de Landazuri et Seitz, qui considérent le degré minimal des représentations pour les groupes de Chevalley sur les corps finis, tout en offrant une preuve plus simple que la leur. La seconde partie de la thése à trait à la théorie algébrique des nombres. Un polynome monogéne $f$ est un polynome unitaire irréductible à coefficients entiers qui endengre un corps de nombres monogéne. Pour un nombre premier $q$ donné, nous allons montrer, en utilisant le théoréme de densité de Tchebotariov, que la densité des nombres premiers $p$ tels que $t^q -p$ soit monogéne est supérieure ou égale à $(q-1)/q$. Nous allons également démontrer que, quand $q=3$, la densité des nombres premiers $p$ tels que $\mathbb{Q}(\sqrt[3]{p})$ soit non monogéne est supérieure ou égale à $1/9$.