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Larger Size (larger + size)
Terms modified by Larger Size Selected AbstractsRainfall, dispersal and reproductive inhibition in eusocial Damaraland mole-rats (Cryptomys damarensis)JOURNAL OF ZOOLOGY, Issue 4 2002A. J. Molteno Abstract Non-reproductive female Damaraland mole-rats Cryptomys damarensis that were caught before a period of good rainfall (during which 90% of the average annual fell) (Group 1), exhibited a significantly lower pituitary sensitivity to gonadotrophin-releasing hormone compared to non-reproductive females (Group 2) caught in the same area, close to the end of the wet period. Group 2 were also significantly heavier than Group 1. Pituitary sensitivity was not significantly correlated to body mass within either group of females, nor within groups of reproductive males and non-reproductive males from a laboratory held colony. This suggests that rainfall may have resulted in the simultaneous, but unrelated, increase in pituitary sensitivity and body mass. Larger size and reduced sexual inhibition assist dispersal and the probability of successful independent reproduction, during periods when environmental constraints on dispersal are relaxed. These findings support the hypothesis that low rainfall may be an important constraint on dispersal and an important factor promoting the evolution of reproductive inhibition, and consequently eusociality, in this species. [source] Hypoxia-based habitat compression of tropical pelagic fishesFISHERIES OCEANOGRAPHY, Issue 6 2006ERIC D. PRINCE Abstract Large areas of cold hypoxic water occur as distinct strata in the eastern tropical Pacific (ETP) and Atlantic oceans as a result of high productivity initiated by intense nutrient upwelling. We show that this stratum restricts the depth distribution of tropical pelagic marlins, sailfish, and tunas by compressing the acceptable physical habitat into a narrow surface layer. This layer extends downward to a variable boundary defined by a shallow thermocline, often at 25 m, above a barrier of cold hypoxic water. The depth distributions of marlin and sailfish monitored with electronic tags and average dissolved oxygen (DO) and temperature profiles show that this cold hypoxic environment constitutes a lower habitat boundary in the ETP, but not in the western North Atlantic (WNA), where DO is not limiting. Eastern Pacific and eastern Atlantic sailfish are larger than those in WNA, where the hypoxic zone is much deeper or absent. Larger sizes may reflect enhanced foraging opportunities afforded by the closer proximity of predator and prey in compressed habitat, as well as by the higher productivity. The shallow band of acceptable habitat restricts these fishes to a very narrow surface layer and makes them more vulnerable to over-exploitation by surface gears. Predictably, the long-term landings of tropical pelagic tunas from areas of habitat compression have been far greater than in surrounding areas. Many tropical pelagic species in the Atlantic Ocean are currently either fully exploited or overfished and their future status could be quite sensitive to increased fishing pressures, particularly in areas of habitat compression. [source] Seed weevils living on the edge: pressures and conflicts over body size in the endoparasitic Curculio larvaeECOLOGICAL ENTOMOLOGY, Issue 3 2009RAÚL BONAL Abstract 1.,Body size in parasitic insects can be subjected to contrasting selective pressures, especially if they complete their development within a single host. On the one hand, a larger body size is associated with a higher fitness. On the other hand, the host offers a discrete amount of resources, thus constraining the evolution of a disproportionate body size. 2.,The present study used the weevil Curculio elephas as a study model. Larvae develop within a single acorn, feeding on its cotyledons, and larval body size is strongly related to individual fitness. 3.,The relationship between larval and acorn size was negatively exponential. Larval growth was constrained in small acorns, which did not provide enough food for the weevils to attain their potential size. Larval size increased and levelled off in acorns over a certain size (inflexion point), in which cotyledons were rarely depleted. When there were more than one larva per acorn, a larger acorn was necessary to avoid food depletion. 4.,The results show that C. elephas larvae are sometimes endoparasitic, living on the edge of host holding capacity. If they were smaller they could avoid food depletion more easily, but the fitness benefits linked to a larger size have probably promoted body size increase. The strong negative effects of conspecific competition may have possibly influenced female strategy of laying a single egg per seed. 5.,Being larger and fitter, but always within the limits of the available host sizes, may be one main evolutionary dilemma in endoparasites. [source] Male-biased size dimorphism in ichneumonine wasps (Hymenoptera: Ichneumonidae) , the role of sexual selection for large male sizeECOLOGICAL ENTOMOLOGY, Issue 3 2005Tiit Teder Abstract., 1.,Sexual differences in body size are expected to evolve when selection on female and male sizes favours different optima. 2.,Insects have typically female-biased size dimorphism that is usually explained by the strong fecundity advantage of larger size in females. However, numerous exceptions to this general pattern have led to the search for selective pressures favouring larger size in males. 3.,In this study, the benefits of large size were investigated in males of four species of ichneumonine wasps, a species-rich group of parasitoids, many representatives of which exhibit male-biased size dimorphism. 4.,Mating behaviour of all ichneumonine wasps are characterised by pre-copulatory struggles, in the course of which males attempt to override female reluctance to mate. A series of laboratory trials was conducted to study the determinants of male mating success. 5.,A tendency was found for larger males as well as those in better condition to be more successful in achieving copulations. Size dimorphism of the species studied, mostly male-biased in hind tibia length but female-biased in body weight, indicates that sexual selection in males favours longer bodies and appendages rather than larger weight. 6.,The qualitative similarity of the mating patterns suggests that sexual selection cannot completely explain the considerable among-species differences in sexual size dimorphism. 7.,The present study cautions against using various size indices as equivalents for calculating sexual size dimorphism. 8.,It is suggested that female reluctance in ichneumonine wasps functions as a mechanism of female mate assessment. [source] The costs and benefits of fast livingECOLOGY LETTERS, Issue 12 2009Karen E. Rose Abstract Growth rates play a fundamental role in many areas of biology (Q. Rev. Biol., 67, 1992, 283; Life History Invariants. Some Explorations of Symmetry in Evolutionary Biology, 1993; Philos. Trans. R. Soc. Lond. B Biol. Sci., 351, 1996, 1341; Plant Strategies, Vegetation Processes, and Ecosystem Properties, 2002; Trends Ecol. Evol., 18, 2003, 471; Q. Rev. Biol., 78, 2003, 23; J. Ecol., 95, 2007, 926.) but the cost and benefits of different growth rates are notoriously difficult to quantify (Q. Rev. Biol., 72, 1997, 149; Funct. Ecol., 17, 2003, 328). This is because (1) growth rate typically declines with size and yet the most widely used growth measure , relative growth rate or RGR (conventionally measured as the log of the ratio of successive sizes divided by the time interval) , is not size-corrected and so confounds growth and size, (2) organisms have access to different amounts of resource and (3) it is essential to allow for the long-term benefits of larger size. Here we experimentally demonstrate delayed costs and benefits of rapid growth in seven plant species using a novel method to calculate size-corrected RGR. In control treatments, fast-growing plants benefited from increased reproduction the following year; however, fast-growing plants subjected to an experimental stress treatment (defoliation) showed strongly reduced survival and reproduction the following year. Importantly, when growth was estimated using the classical RGR measure, no costs or benefits were found. These results support the idea that life-history trade-offs have a dominant role in life-history and ecological theory and that the widespread failure to detect them is partly due to methodological shortcomings. Ecology Letters (2009) 12: 1379,1384 [source] Size-Related Advantages for Reproduction in a Slightly Dimorphic Raptor: Opposite Trends between the SexesETHOLOGY, Issue 12 2007Fabrizio Sergio Despite many comparative analyses and more than 20 proposed hypotheses, there is still little consensus over the factors promoting the evolution of reversed sexual dimorphism (RSD) in raptorial species. Furthermore, intrapopulation studies, which may elucidate how RSD is maintained once evolved, have been surprisingly scarce and only focused on a handful of species with medium to high dimorphism. We examined the reproductive advantages associated with body size and condition, measured in the pre-laying period, in a diurnal raptor with low sexual dimorphism, the black kite (Milvus migrans). The study population was essentially monomorphic in size. For females, there was an evidence of reproductive benefits associated with larger size and/or with better body condition. Larger females had also access to higher quality partners and territories, consistent with the ,intrasexual selection' hypothesis, by which members of the larger sex enjoy size-related advantages in intrasexual competition over a scarce resource, the smaller sex. Opposite trends emerged for males: smaller, leaner males had higher breeding output, consistent with the ,small efficient male' hypothesis. Overall, the fact that we observed in an essentially monomorphic population the same selection pressures previously found in species with marked dimorphism suggests that such reproductive advantages may be counterbalanced in our study model by opposite selection pressures during other stages of the life cycle. This casts some doubts on the evolutionary significance of studies focusing exclusively on reproduction and calls for the need of more comprehensive analyses incorporating trait-mediated differentials in survival and recruitment. [source] Differential Sperm Priming by Male Sailfin Mollies (Poecilia latipinna): Effects of Female and Male SizeETHOLOGY, Issue 3 2004Andrea S. Aspbury Recent interest in sperm competition has led to a re-evaluation of the ,cheap sperm' assumption inherent in many studies of sexual selection. In particular, mounting evidence suggests that male sperm availability can be increased by the presence of females. However, there is little information on how this interacts with male traits presumably affected by female mate choice, such as larger size. This study examines the effects on male sperm availability of female presence, male body size, and female body size in the sailfin molly, Poecilia latipinna. Individual males of variable body sizes were isolated in divided tanks for 3 d, after which time either a female or no female was added to the other side of the tank. Prior to the treatments, larger males had more stripped sperm than smaller males. Female presence significantly increased the amount of sperm males primed, but this effect was strongest in small males. Furthermore, males showed a greater priming response in the presence of larger females than in the presence of smaller females. These results demonstrate that the presence of sexually mature females increases the amount of sperm males have for insemination. Furthermore, traits that indicate female fecundity may be used by males as cues in male mate choice. [source] EXTREME SELECTION ON SIZE IN THE EARLY LIVES OF FISHEVOLUTION, Issue 8 2010Kestrel O. Perez Although fitness typically increases with body size and selection gradients on size are generally positive, much of this information comes from terrestrial taxa. In the early life history of fish, there is evidence of selection both for and against larger size, leaving open the question of whether the general pattern for terrestrial taxa is valid for fish. We reviewed studies of size-dependent survival in the early life history of fish and obtained estimates of standardized selection differentials from 40 studies. We found that 77% of estimated selection differentials favored larger size and that the strength of selection was more than five times that seen in terrestrial taxa. Selection decreased with study period duration and initial length, and disruptive selection occurred significantly more frequently than stabilizing selection. Contrary to expectations from Bergmann's rule, selection on size did not increase with latitude. [source] Combining fishery prohibition with stocking of landlocked salmon, Salmo salar L.: an effort to gain bigger yield and individual sizeFISHERIES MANAGEMENT & ECOLOGY, Issue 6 2000P. Hyvärinen After stocking landlocked salmon, Salmo salar L., in Lake Änättijärvi, all fishing was prohibited for 18 months to provide time for the fish to establish and reach a larger size prior to capture. The potential benefit of the fishery prohibition was severely diminished by emigration of the stocked fish down the watercourse to other lakes. Only 19% of the recaptures of Carlin-tagged individuals came from Lake Änättijärvi. Also, the CPUE of test fishing in Lake Änättijärvi indicated a steep decline in the density of stocked fish during the fishery prohibition period. The mean weight of landlocked salmon in the combined recaptures from Lake Änättijärvi and other lakes downstream was 660 g. When fishing was not prohibited, the corresponding mean weight at recapture was 442 g. It is recommended that landlocked salmon stocking should be carried out in lakes with relatively low fishing pressure. [source] Polydisperse Spindle-Shaped ZnO Particles with Their Packing Micropores in the Photoanode for Highly Efficient Quasi-Solid Dye-Sensitized Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Yantao Shi Abstract In this paper, a novel hierarchically structured ZnO photoanode for use in quasi-solid state dye-sensitized solar cells (DSCs) is presented. The film is composed of polydisperse spindle-shaped ZnO particles that are prepared through direct precipitation of zinc acetate in aqueous solution. Without additional pore-forming agents, the microporous structure is well constructed through the packing of polydisperse ZnO particles. In the film, small ZnO particles are able to improve interparticle connectivity and offer a large internal surface area for sufficient dye-adsorption; on the other hand, particles of larger size can enhance the occurrence of light-scattering and introduce micropores for the permeation of quasi-solid state electrolytes. Meanwhile, morphologies, particle size, and specific areas of the products are controlled by altering the reactant concentration and synthetic temperature. Combined with a highly viscous polymer gel electrolyte, a device based on this ZnO photoanode shows high conversion efficiencies, 4.0% and 7.0%, under 100 and 30,mW cm,2 illumination, respectively. Finally, the unsealed device is demonstrated to remain above 90% of its initial conversion efficiency after 7 days, showing excellent stability. [source] Veligers of an introduced bivalve, Limnoperna fortunei, are a new food resource that enhances growth of larval fish in the Paraná River (South America)FRESHWATER BIOLOGY, Issue 9 2010ESTEBAN M. PAOLUCCI Summary 1.,Larvae of ,sábalo', Prochilodus lineatus, whose adults represent over 60% of overall fish biomass in the Río de la Plata Catchment, have been observed to feed intensively on veligers of the exotic bivalve Limnoperna fortunei. 2.,To assess the effects of this dietary shift on the growth of P. lineatus, 28-day laboratory experiments were carried out feeding newly hatched P. lineatus larvae with three diets: zooplankton artificially enriched with L. fortunei veligers; natural zooplankton; and zooplankton artificially enriched with cladocerans and copepods. The average length, weight and gut contents of the fish larvae were assessed weekly and metabolic rates of fish larvae were measured. 3.,Proportions of veligers in gut contents were always higher than those in the experimental diet: 100, 76 and 21% for veliger-enriched, natural and low-veliger diets, respectively. Larvae fed a veliger-enriched diet grew to a significantly larger size than larvae fed the other two diets. In energetic balance comparisons using metabolic rates and prey energy content, all three diets were sufficient to support metabolism and growth. The greatest values of excess energy at the end of each week were in the veliger-enriched experiments. 4.,Feeding on veligers of L. fortunei significantly enhances the growth of P. lineatus larvae and supports the idea that this new and abundant resource is selectively preyed upon by P. lineatus during its larval stage. Higher growth rates may stem from the higher energy contents of veligers compared to crustaceans and/or from the lower energy costs of capturing slower prey. [source] Effects of temperature and food quality on anuran larval growth and metamorphosisFUNCTIONAL ECOLOGY, Issue 5 2002D. Álvarez Summary 1Anurans exhibit high levels of growth-mediated phenotypic plasticity in age and size at metamorphosis. Although temperature and food quality exert a strong influence on larval growth, little is known about the interacting effects of these factors on age and size at metamorphosis. 2Plasticity in growth rates, maximum larval mass, mass loss, larval period and size at metamorphosis was examined in Iberian Painted Frogs (Discoglossus galganoi Capula, Nascetti, Lanza, Bullini & Crespo 1985) under different combinations of temperature and diet quality. 3Temperature and diet had strong effects on the maximum size reached by tadpoles throughout the premetamorphic stages. Larval body mass varied inversely with temperature. The effect of diet depended on temperature; larvae fed on a ,carnivorous' diet (rich in protein and lipids) achieved a larger size than larvae offered an ,herbivorous' diet (rich in carbohydrates) at 17 °C but not at 12 or 22 °C. 4Larval period was insensitive to diet composition, and varied only with temperature. Primarily the interacting effects of food quality and temperature affected size at metamorphosis. Size at metamorphosis varied inversely with temperature under the plant- and the animal-based diets. However, the carnivorous diet resulted in bigger metamorphs at 17 and 22 °C, but did not influence final mass at 12 °C. Maximum size over the larval period explained most of the variation in mass loss after the premetamorphic growing phase. [source] Effects of elevated CO2 on the size structure in even-aged monospecific stands of Chenopodium albumGLOBAL CHANGE BIOLOGY, Issue 4 2003HISAE NAGASHIMA Abstract To investigate the effect of elevated CO2 on the size inequality and size structure, even-aged monospecific stands of an annual, Chenopodium album, were established at ambient and doubled CO2 with high and low nutrient availabilities in open top chambers. The growth of individual plants was monitored non-destructively every week until flowering. Elevated CO2 significantly enhanced plant growth at high nutrients, but did not at low nutrients. The size inequality expressed as the coefficient of variation tended to increase at elevated CO2. Size structure of the stands was analyzed by the cumulative frequency distribution of plant size. At early stages of plant growth, CO2 elevation benefited all individuals and shifted the whole size distribution of the stand to large size classes. At later stages, dominant individuals were still larger at elevated than at ambient CO2, but the difference in small subordinate individuals between two CO2 levels became smaller. Although these tendencies were found at both nutrient availabilities, difference in size distribution between CO2 levels was larger at high nutrients. The CO2 elevation did not significantly enhance the growth rate as a function of plant size except for the high nutrient stand at the earliest stage, indicating that the higher biomass at elevated CO2 at later stages in the high nutrient stand was caused by the larger size of individuals at the earliest stage. Thus the effect of elevated CO2 on stand structure and size inequality strongly depended on the growth stage and nutrient availabilities. [source] Evaluation of a laser-assisted particle sizing/settling velocity determination techniqueHYDROLOGICAL PROCESSES, Issue 9 2006Dr I. G. Droppo Abstract The use of predictive models for the understanding and management of sediment and contaminant transport generally requires knowledge of particle size and settling velocity. Particle size is often obtained by direct measurements, and the settling velocities are usually predicted using the Stokes' law (or a modification thereof) for single-grained spherical particles. Such measurements and estimates are not satisfactory measures for cohesive sediments, which exist as agglomerated particles called flocs and whose behaviour is significantly different from that of the single-grained particles. Direct measurement of settling velocity and size using optical methods in settling columns has also been employed to improve these predictions; however, the subjectivity in determining which particles are in focus results in unreliable size data. An out-of-focus particle will generally possess a larger size than in reality. This paper evaluates a laser-assisted particle sizing/settling velocity determination technique's ability to eliminate the subjectivity and improve particle-sizing accuracy during settling column experiments. Although the diffraction of light by the translucent standard beads (used for evaluating the technique's accuracy for determining particle size) posed a problem, the results suggest that this technique has potential for assisting researchers to obtain the most accurate settling particle size data possible. Copyright © 2005 John Wiley & Sons, Ltd. [source] Birth characteristics and adult cancer incidence: Swedish cohort of over 11,000 men and womenINTERNATIONAL JOURNAL OF CANCER, Issue 4 2005Valerie A. McCormack Abstract Associations between larger size at birth and increased rates of adult cancer have been proposed but few empirical studies have examined this hypothesis. We investigated overall and site-specific cancer incidence in relation to birth characteristics in a Swedish population-based cohort of 11,166 singletons born in 1915,1929 for whom we have detailed obstetric data and who were alive in 1960. A total of 2,685 first primary cancers were registered during follow-up from 1960 to 2001. A standard deviation (SD) increase in birth weight for gestational age (GA) was associated with (sex-adjusted) increases of 13% (95% CI = 0.03,0.23) in the rates of digestive cancers and of 17% (95% CI = 0.01,0.35) in the rates of lymphatic cancers. Women who had higher birth weights also had increased rates of breast cancer under age 50 years (by 39% per SD increase; 95% CI = 0.09,0.79), but reduced rates (by 24%; 95% CI = 0.07,0.38) of endometrial (corpus uteri) cancer at all ages. There was no evidence of associations with other cancer sites. For overall cancer incidence, men had an 8% increased risk at all ages per SD increase in birth weight for GA while women only had an increased risk under age 50 years (mainly driven by the association with breast cancer). These findings provide evidence of a modest association of birth size and adult cancer risk, resulting from positive associations with a few cancer sites and a possible inverse association with endometrial cancer. © 2005 Wiley-Liss, Inc. [source] Effects of SiO2 nanoparticles on the performance of carboxyl-randomized liquid butadiene,acrylonitrile rubber modified epoxy nanocompositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2007Minfeng Zeng Abstract The effects of SiO2 nanoparticles on the performance of carboxyl-randomized liquid butadiene,acrylonitrile rubber (CRBN) modified epoxy resin (EP) nanocomposites were studied. With the addition of an appropriate amount of SiO2 (2%) to EP/CRBN (95/5), the nanocomposites could achieve the desired impact strength and modulus. The morphology of the nanocomposites was studied with scanning electron microscopy and transmission electron microscopy. The nanocomposites showed a three-phase system; both the rubber particles and SiO2 nanoparticles showed uniform dispersions in the EP matrix, with their phases all nanosized. A good correlation between the free-volume hole radius and mechanical properties was found. The introduction of a small amount of nanoparticles (both rubber and SiO2) into EP led to the formation of interactions between the EP and nanoparticles. The interactions restricted the segment motion and the mobilization of the EP chains and then reduced the free-volume concentration in the amorphous region of EP. The fact that the average free-volume hole radius of EP/CRBN was larger than that of pure EP was mainly attributed to the contribution of the larger size of the free-volume holes within the rubber phase. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Effects of load and indicator type upon occlusal contact markingsJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008Muhammad N. Saad Abstract Statement of Problem: Clinicians use occlusal indicators to identify tooth contacts. However, the reliability of these indicators has been questioned. At times occlusal contacts are not identified or false positive occlusal contacts are observed. Purpose of Study: This study was designed to compare the number and size of occlusal indicator marks from both thick and thin occlusal indicator materials with different loads. Materials and Methods: Ivorine casts were articulated and mounted on an Hana Mate nonadjustable articulator. Loads of 100N, 150N, and 200N were applied with Accufim (25 ,m thick, Parkell, Farmingdale, NY) and Articulating Paper (60 ,m thick, G.E. Rudischauer Dental Articulating Paper, Brooklyn, NY) as the occlusal indicators. A fresh piece of indicator was used for each trial. Comparisons were made of the number and size of the contacts for both the thick and thin occlusal indicators at the different loads. Results: Observation of the marks recorded with the thicker occlusal indicator demonstrated both a greater number marks and a larger size to the marks when compared to the thinner Accufilm, p , 0.02,0.0001. However, there was no significant increase in the number or size of the marks with an increased load for either material. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] Sexually antagonistic selection on primate sizeJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2002P. Lindenfors Abstract Male intrasexual selection in haplorhine primates has previously been shown to increase male size and to a lesser degree also female size. I address the following questions: (1) why does female size increase when the selection is on males, and (2) why does female size not increase to the same extent as that of males. The potential for correlational selection on females through increased resource competition was analysed with independent contrasts analyses. No such effect was found, nor did matched pairs comparisons reveal females to increase in size because of selection to bear larger male offspring. Instead further matched pairs analyses revealed higher female postpartum investment, as indicated by a longer lactation period, in more sexually selected species, also after correcting for body weight. Concerning the second question, independent contrast analyses showed that large size has had negative effects on female reproductive rate across the primate order. Matched-pairs analyses on haplorhines revealed that females of species in more polygynous clades have lower reproductive rates than females of species in less polygynous clades. This is also true after the effects of body weight are removed. These results, both when correcting for body weight and when not, suggest that sexual selection has shifted female size from one favouring female lifetime fecundity to one favouring male success in competition. This depicts antagonistic selection pressures on female size and a trade-off for females between the ecologically optimal size of their foremothers and the larger size that made their forefathers successful. [source] Increased body size confers greater fitness at lower experimental temperature in male Drosophila melanogasterJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2000Reeve Genetic variation of body size along latitudinal clines is found globally in Drosophila melanogaster, with larger individuals encountered at higher latitudes. Temperature has been implicated as a selective agent for these clines, because the body size of laboratory populations allowed to evolve in culture at lower temperatures is larger. In this study, we investigated the hypothesis that larger size is favoured at lower temperature through natural selection on adult males. We measured life-span and age-specific fertility of males from lines of flies artificially selected for body size at two different experimental temperatures. There was an interaction between experimental temperature and body size selection for male fitness; large-line males were fitter than controls at both temperatures, but the difference in fitness was greater at the lower experimental temperature. Smaller males did not perform significantly differently from control males at either experimental temperature. The results imply that thermal selection for larger adult males is at least in part responsible for the evolution of larger body size at lower temperatures in this species. The responsible mechanisms require further investigation. [source] Growth, maturity and fecundity of wolffish Anarhichas lupus L. in Icelandic watersJOURNAL OF FISH BIOLOGY, Issue 4 2006Á. Gunnarsson Fecundity, maturity and the relationship between growth and maturity of common wolffish Anarhichas lupus were studied in Icelandic waters. A total of 788 female common wolffish were sampled in two areas: one in the relatively warm sea west of Iceland and the other in the colder sea east of Iceland. No difference was detected in fecundity of common wolffish between areas. The time from the onset of the cortical alveolus stage until spawning, was on average, 10 years in the east and 8 years in the west area. Common wolffish in the east area reached cortical alveolus stage, on average, at a greater age but similar size compared to common wolffish in the west area. Similarly, common wolffish started spawning, on average, at greater age and larger size in the east than in the west area. Common wolffish grew faster in the west than in the east area. Spawning common wolffish grew faster than common wolffish at the cortical alveolus stage in both areas. The relationship between growth and maturity for common wolffish in Icelandic waters appeared to be related to temperature, characterized by fast growth and early maturation in the west and slower growth and delayed maturation in the east. [source] The New Zealand common smelt: biology and ecologyJOURNAL OF FISH BIOLOGY, Issue 1 2005F. J. Ward The common smelt is one of the most widespread indigenous freshwater fishes in New Zealand. One other member of the family Retropinnidae, Stokellia anisodon(Stokell), is present but is confined to a small region of the South Island. There are many diadromous as well as river and lake resident populations, the latter, sometimes a result of introductions to serve as forage fish for trout. Diadromous smelt spawn during austral autumn,winter on sand bars of lower riverine reaches. Larval stages inhabit coastal marine waters, and the postlarvae to immature stages re-enter rivers and some lowland lakes. Diadromous smelt are distinguished from lowland lake resident forms by high vertebral but low gill raker numbers and larger size and from those present in some isolated waters, by high vertebral numbers alone. Lake or reservoir resident smelt usually spawn in austral spring,summer on sandy shallows at stream mouths or along shorelines. Verified smelt ages (otolith analyses) indicate that in some populations most smelt mature and spawn after c. 1 year. Adult smelt feed on a spectrum of primarily invertebrate animals ranging from small zooplankters to insects and occasionally small fishes. Smelt are a major prey for both brown trout and rainbow trout. Adult smelt are a minor food for the Maori people. As postlarvae they are a component of a few ,whitebait' fisheries. Most smelt populations are increasingly affected by environmental changes induced by human activities. Although many studies have examined problems affecting smelt, further effort is required, along with more basic research. [source] An Empirical Analysis of Triple Bottom-Line Reporting and its Determinants: Evidence from the United States and JapanJOURNAL OF INTERNATIONAL FINANCIAL MANAGEMENT & ACCOUNTING, Issue 2 2007Li-Chin Jennifer Ho This paper investigates triple bottom-line (TBL) disclosures of 50 of the largest US and Japanese companies. Twenty disclosure criteria were developed for each of the TBL disclosure areas: economic, social, and environmental. Disclosure information was examined in annual reports, stand-alone reports, and special website reports. Regression analysis was used to examine empirically the determinants of TBL disclosure practice. Our results indicate that, for total TBL disclosure (combining economic, social, and environmental categories), the extent of reporting is higher for firms with larger size, lower profitability, lower liquidity, and for firms with membership in the manufacturing industry. Further analysis indicates that the results for the total TBL disclosure are primarily driven by non-economic disclosures. We also find that the extent of overall TBL reporting is higher for Japanese firms, with environmental disclosure being the key driver. This result could be attributed to the differences in national cultures, the regulatory environment, and other institutional factors between the United States and Japan. [source] Optical and physicochemical properties of silica-supported TiO2 photocatalystsAICHE JOURNAL, Issue 8 2006Javier Marugán Abstract Commercial applications of photocatalysis in slurry reactors employing titanium dioxide particles present the disadvantage of the additional cost associated with the downstream catalyst separation. In past years a significant effort has been made to develop supported titania photocatalysts on particles of larger size in order to facilitate the sedimentation recovery process. In this work, two different silica materials have been used for preparing immobilized catalysts. Their physicochemical characteristics have been compared with those corresponding to two commercially available unsupported titanium dioxide catalysts. However, for reaction kinetics and reactor design purposes, three additional properties must be known: (i) the spectral specific radiation absorption coefficient, (ii) the spectral specific radiation scattering coefficient, and (iii) the asymmetry factor of a model for the angular distribution of the scattered photons (the phase function). They have been determined with specially designed spectrophotometer transmission, diffuse transmittance, and diffuse reflectance experiments and constitute the most significant addition to this contribution. © 2006 American Institute of Chemical Engineers AIChE J, 2006 [source] Arborescent polymers and other dendrigraft polymers: A journey into structural diversityJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2007Mario Gauthier Abstract Arborescent polymers are characterized by a dendritic, multilevel branched architecture derived from successive grafting reactions. In spite of their much larger size, these materials display properties analogous to dendrimers and hyperbranched polymers, the two other dendritic polymer families. The distinguishing features of arborescent polymers are their assembly from polymeric building blocks of uniform size and their very high molecular weights attained in few synthetic steps. This article offers an overview of the historical aspects of the development of dendrigraft polymers, starting from our initial efforts on the synthesis of arborescent polystyrenes. Major subsequent developments in the synthetic techniques from our and other research groups allowing the synthesis of dendrigraft copolymers, tailoring of the structural characteristics of the molecules, and further simplifications to their synthesis are also reviewed, with emphasis over the broad range of architectures attainable in these systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3803,3810, 2007 [source] Search for predictors of cooking quality of marrowfat pea (Pisum sativum L) cultivarsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2001Geoffrey P Savage Abstract The grain from 116 marrowfat pea breeding lines was assessed subjectively using current visual methods and then analysed objectively for L*a*b* colour, hydration capacity and cooking quality. The data show that the current method of selecting genotypes by subjective methods is not able to select marrowfat peas for specific processing uses. However, an objective measure, the ,a* value of the dry grain, was a very good predictor (p,<,0.001) for the hydrated and cooked green colour. Cultivars which have a high hydration coefficient may be more suitable for canning and deep frying because they hydrate to a larger size, while cultivars with a high bulk density and a darker green grain are more suitable for use as extrusion products. © 2001 Society of Chemical Industry [source] Growth and Survival of the Blood Ark Anadara ovalis (Bruguière, 1789) Cultured in Mesh Bags on Soft-Bottom Sediments in the Coastal Waters of GeorgiaJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 3 2001Alan J. Power Annual growth and survival rates were measured for blood arks Anadara ovalis (Bruguière 1789) cultured in mesh bags that were placed at the spring-low-water mark in soft-bottom sediments of the Skidaway River, Georgia. The feasibility of growing the arks to a marketable size using this technique was assessed by determining the effects of stocking density and biofouling on growth and survival. Two replicate densities of 190 (low) and 400 (high) arks per mesh bag (mean shell length 31.97 mm) were planted in early September 1999. In April 2000, the arks cultured at the lower density had a significantly larger size (44.99 mm) than at the higher density (43.83 mm), with growth rates of 1.85 mdmo, and 1.69 mm/mo, respectively. Growth decreased considerably in the subsequent months (low: 0.17 mm/mo; high: 0.30 mm/mo). There was no significant difference in ark size between treatments after a year's growth in late August 2000 (low: 45.76 mm, 1.15 mm/mo; high: 45.31 mm, 1.11 mm/mo). Similarly, no significant difference in annual survival rates between stocking densities occurred (low: 42.89%; high: 40.25%). The present findings indicate that this method of growing arks to market size has potential to contribute to future endeavors to develop an aquaculture fishery for the blood ark in the coastal waters of Georgia. [source] Resting breathing frequency in aquatic birds: a comparative analysis with terrestrial speciesJOURNAL OF ZOOLOGY, Issue 2 2009J. P. Mortola Abstract Several studies have indicated that in birds breathing frequency (f, breaths min,1) scales to the ,1/3 of body weight (W, kg); this is different from the ,1/4 of mammals. We wondered if this discrepancy was due to the peculiar scaling pattern of aquatic birds, as is the case of aquatic mammals. In fact, we had noted previously that the allometric scaling of f differs considerably between aquatic and terrestrial mammals, respectively, W,0.42 and W,0.25. Measurements of f were obtained in 48 aquatic birds of 22 species and in 35 terrestrial birds of 27 species, during resting conditions on land. Additional data from 11 aquatic and 14 terrestrial species, different from the ones measured, were obtained from the literature. The allometric curve of all species combined (terrestrial and aquatic, n=74) was f=13.3W,0.36, similar to what is reported in previous studies. However, the allometric curve of the aquatic species (n=33, f=14.5W,0.56) differed greatly (P<0.001) from that of the terrestrial species (n=41, f=13.4W,0.26). On average, f of aquatic birds of the 3,5 kg range was 63%, and that of birds of larger size was 57%, of the values of terrestrial birds of similar W. We conclude that, as in mammals, also in terrestrial birds f scales to the ,1/4 exponent of W. The similarity of the scaling patterns of f between aquatic birds and mammals suggests a common breathing adaptation to life in the aquatic environment irrespective of phylogenetic relations. [source] Sexual dimorphism of body size and shell shape in European tortoisesJOURNAL OF ZOOLOGY, Issue 4 2003Ronald E. Willemsen Adult body size and shape were examined in almost 1400 individuals of the tortoises Testudo graeca, T. hermanni and T. marginata from Greece. The size at maturity was greater in females than in males in all three species. Maximum and mean adult sizes were also greater in females than in males in T. graeca and T. hermanni. Males grew to a larger size than females in T. marginata, and mean adult size was similar in the sexes in this species. Sexual dimorphism of shape (adjusted for size covariate) was shown in most of the characters examined, and the degree of this dimorphism differed significantly among the three species. Differences were related to their contrasting courtship behaviours: horizontal head movements and severe biting in T. marginata, vertical head bobs and carapace butting in T. graeca, and mounting and tail thrusting in T. hermanni. There was no difference in the frequency of observations of courtship or fighting among the three species, but courtship was about 10 times more common than combat in males. All species showed greatest courtship activity in autumn; copulation was rarely observed in T. hermanni (only 0.36% of courting males) and not seen in the other species in the field. Observations made throughout the activity season indicated that feeding was equally common in males and females in all three species. Differences in shape were more likely to be the result of sexual selection than of natural selection for fecundity. Detailed predictions are made for sexual dimorphism of other characters in these species. [source] In Situ Coacervated Microcapsules with Filled Polyelectrolytes and Charge-Controlled Permeation for Dye MoleculesMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2008Feng Wang Abstract Microcapsules with charge-controlled permeation for electrolytes were fabricated by an in situ coacervation method in the presence of polyelectrolyte during core removal. A layer of PAH was adsorbed onto PSS-doped CaCO3 microparticles, followed by crosslinking of the PAH layer with GA and core removal in a solution of EDTA with or without PAH. In the presence of PAH, microcapsules with a larger size, weight and PSS content than with PAH were obtained. Microcapsules produces without PAH showed a unique feature of charge-controlled permeation for electrolytes: negatively charged probes were completely rejected, but positively charged ones were attracted. [source] Size-Frequency Distributions of Miocene Micromorphic Brachiopods: Interpretation Tool for Population DynamicsMARINE ECOLOGY, Issue 1 2002Maria Aleksandra Bitner Abstract. The population dynamics of the fossil micromorphic brachiopods from shallow-water Miocene deposits (calcareous clays to hard bottom of reef cavities) of the Roztocze Hills, south-eastern Poland were studied by means of size-frequency distributions. The following four species, which all also occur in the Recent Mediterranean, were used for the study: Megathiris detruncata (Gmelin), Argyrotheca cuneata (Risso), A. cordata (Risso) and Megerlia truncata (Linnaeus). The size-frequency distributions for 28 assemblages studied here vary widely, even within a single species, from right-skewed, through bell-shaped to polymodal; no left-skewed distribution was noted. The size-frequency distributions with a large peak in the smaller size classes represent mostly assemblages collected from marly deposits. Those assemblages may be interpreted as inhabiting soft bottoms where small brachiopods are more vulnerable to burial by sediment and/or clogging effects on the lophophore apparatus. The assemblages collected from the reef cavities produced bell-shaped size-frequency distributions or distributions with a relatively high percent of larger individuals. This is because the protected hard bottom cryptic habitats are characterised by lower juvenile mortality and enable the brachiopods to reach a larger size. These results suggest that environmental factors play a crucial role in shaping brachiopod population structures, and that empty shells can be used to study population dynamics as well in Recent environments. [source] | ||||||||||||||||||||||||||||||||||||||||