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Selected AbstractsForaging in nature: foraging efficiency and attentiveness in caterpillars with different diet breadthsECOLOGICAL ENTOMOLOGY, Issue 4 2004E. A. Bernays Abstract., 1. Seventy-seven individual last-instar caterpillars foraging in the field were examined for 6 h each. They represented four species of Arctiidae of similar size and habitat use. Two, Hypocrisias minima and Pygarctia roseicapitis, are specialists restricted to particular plant genera. The other two, Grammia geneura and Estigmene acrea, are extreme generalists that use many host plant species from multiple plant families. 2. Parameters of behavioural efficiency were monitored. Generalists spent more time walking, rejected more potential host plants, took longer to decide to feed after inspecting a plant, and took relatively more small feeding bouts compared with specialists. 3. This is the first test of differential foraging efficiency in the field in relation to diet breadth of insects and the data indicate that generalists are less efficient in their foraging activities and may suffer from divided attention. The need for attentiveness to enhance efficiency and thereby reduce ecological risk is discussed. [source] Anti-Predator Strategies and Grouping Patterns in White-Tailed Deer and Mule DeerETHOLOGY, Issue 4 2001Susan Lingle White-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) are closely related species of similar size that differ in their anti-predator behavior. White-tails flee from coyotes (Canis latrans), whereas mule deer typically stand their ground and attack this predator. I used observations of coyotes hunting deer to identify: (i) changes in group structure made in response to coyotes; and (ii) the relationship between group structure and the risk of predation for each species. In response to coyotes, groups of mule deer merged with other groups and individuals bunched together. Predation attempts were more likely to escalate when groups split and individuals failed to bunch. Coyotes typically attacked mule deer that were in outlying positions, and these deer had to move to central positions to end attacks. Due to the high frequency of attacks on small groups as well as to the level of dilution of risk, individuals in small mule deer groups were at high risk of being attacked compared with those in larger groups. In contrast to mule deer, white-tails made no consistent changes in group size or formation, and coyotes attacked individuals in central as well as in outlying positions. Variation in aspects of group cohesion was not related to the vulnerability of white-tails, and there was no obvious difference in the risk of attack facing individuals in groups of different size. These results suggest that coyote predation selects for relatively large, cohesive groups in mule deer, apparently because this type of group improves their ability to deter coyotes. Coyote predation does not have similar effects on groups formed by white-tails, which use flight rather than deterrence to avoid predation. The benefits of responding cohesively, occupying certain positions within groups, and forming groups of a certain size can vary widely depending on the anti-predator strategies used by an animal. [source] Fore limb bones of late Pleistocene dwarf hippopotamuses (Mammalia, Cetartiodactyla) from Madagascar previously determined as belonging to the crocodylid Voay Brochu, 2007FOSSIL RECORD-MITTEILUNGEN AUS DEM MUSEUM FUER NATURKUNDE, Issue 2 2010Oliver Hampe Abstract A humerus and two radii of juvenile dwarf hippopotamuses are redescribed. The subfossil bones from the collection of the Museum für Naturkunde Berlin were erroneously assigned to the horned crocodile Voay robustus (Grandidier & Vaillant, 1872) by Bickelmann & Klein (2009). All three limb bones presented here belong to immature animals. The epiphyses are not fused, except the proximal extremity of the right radius; and the radius and ulna are also unfused. The two radii are from individuals of different size, whereas the left radius and the humerus are from animals of similar size. Morphologically, the limb bones cannot be identified to species level. A tentative assignment to Hippopotamus madagascariensis is discussed based on the knowledge of the geographic origin on the island. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Reproductive success of the rotifer Brachionus calyciflorus feeding on ciliates and flagellates of different trophic modesFRESHWATER BIOLOGY, Issue 10 2002Silvia Mohr SUMMARY 1. The nutritional value of the bacterivorous ciliate Tetrahymena pyriformis and the algivorous ciliate Coleps sp., as well as the heterotrophic flagellate Chilomonas paramecium and the autotrophic flagellate Cryptomonas ovata, were investigated in population growth experiments using the rotifer B. calyciflorus. The two ciliates, both flagellates, which were of similar size, shape and mobility, were each offered as a sole diet and as a supplement to the alga Monoraphidium minutum, known to support reproduction of B. calyciflorus. 2. To further test nutritional differences between the prey organisms, prey selection experiments were conducted in which B. calyciflorus was able to select between the bacterivorous and algivorous ciliate, and between the heterotrophic and autotrophic flagellate. 3. The results demonstrated that both ciliates and the heterotrophic flagellate were not sufficient to support reproduction of B. calyciflorus when offered as a sole diet. They were, however, a good supplement to algal prey (except for the bacterivorous ciliate T. pyriformis). In the prey selection experiments, B. calyciflorus positively selected for the algivorous Coleps sp. and the autotrophic C. ovata. 4. Overall, ciliates and heterotrophic flagellates may enhance survival of B. calyciflorus, but reproduction of the rotifer is likely to rely on algal prey. Both higher population growth of B. calyciflorus when fed the algivorous Coleps and the autotrophic Cryptomonas, along with their positive selection, give evidence for prey specific differences in nutrition, with algivorous or autotrophic prey species tending to be of higher nutritional value. [source] Physical apertures as constraints on egg size and shape in the Common Musk Turtle, Sternotherus odoratusFUNCTIONAL ECOLOGY, Issue 1 2001P. J. Clark Summary 1,Egg size in turtles often increases with female size, contrary to expectations of optimality. Functional constraints on egg width imposed by the pelvic aperture or the gap between the carapace and plastron (the caudal gap) have been inferred for a few populations but appear inapplicable in others. 2,For Sternotherus odoratus (the Common Musk Turtle), the pelvic aperture was always wider than the width of the female's largest egg by at least 3·7 mm. The caudal gap was narrower than the widest egg for 25·7% of the females. 3,Egg width increased, and elongation (length/width) decreased, as female size and clutch size increased. 4,Females at three ecologically contrasting sites differed appreciably in size but produced eggs of the same mean shape and size, despite the strong within-site changes in both egg size and shape with female size. As the younger females at all sites were of similar age and produced eggs of similar size and shape (again, despite differences in body size), egg size and shape may be age-specific. 5,No optimal egg size prevailed but the scaled residuals of egg size with female mass were less variable than were those for clutch size. [source] Sourcing carbonate pointed stones from the barrier beach of Mantoloking, New Jersey, USAGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 8 2006John P. Vermylen Over 500 previously unidentified, symmetric pointed stones of similar size, shape, color, and texture have been found on the barrier beach of Mantoloking, New Jersey, since 1940. Petrographic, stereo, and scanning electron microscopy analysis reveals that the stones are made of either a biomicritic packstone composed of 50% siliceous microfossil remains ( including sponge spicules and radiolaria) embedded in a micrite matrix or a limestone with abundant angular quartz grains (50,150 ,m wide) surrounded by a calcite matrix. The distinctive shape of the Mantoloking stones is most similar to whetstones used for sharpening scythes. We conducted a worldwide search and discovered one producer of carbonate whetstones: a company in the town of Pradalunga in Northern Italy. Microscope analysis reveals that the Pradalunga source rocks are exact matches for the spicule-rich limestone and angular quartz-rich limestone found in the Mantoloking collection. The whetstones are most likely lost cargo from a wreck offshore of Mantoloking, but the exact source may never be known. © 2006 Wiley Periodicals, Inc. [source] Pay Policies of Firms and Collective Wage Contracts,An Uneasy Partnership?INDUSTRIAL RELATIONS, Issue 1 2006KNUT GERLACH Theoretical considerations suggest that firms establish consistent internal wage structures and pay wage premiums of similar size across occupational groups. Strong evidence for the existence of coherent employer pay policies across occupations is found using a German employer,employee data set. However, firm-specific elements of wage policies are less prevalent in firms applying industry-level collective contracts than in firms with individual-level wage contracts. [source] MR linear contact detection algorithmINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2006A. Munjiza Abstract Large-scale discrete element simulations, as well as a whole range of related problems, involve contact of a large number of separate bodies and an efficient and robust contact detection algorithm is necessary. There has been a number of contact detection algorithms with total detection time proportional to N ln(N) (where N is the total number of separate bodies) reported in the past. In more recent years algorithms with total CPU time proportional to N have been developed. In this work, a novel contact detection algorithm with total detection time proportional to N is proposed. The performance of the algorithm is not influenced by packing density, while memory requirements are insignificant. The algorithm is applicable to systems comprising bodies of a similar size. The algorithm is named MR (Munjiza,Rougier: Munjiza devised the algorithm, Rougier implemented it). In the second part of the paper the algorithm is extended to particles of different sizes. The new algorithm is called MMR (multi-step MR) algorithm. Copyright © 2005 John Wiley & Sons, Ltd. [source] Spatial grouping of United States climate stations using a hybrid clustering approachINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2001Arthur T. DeGaetano Abstract The development of a hybrid clustering technique based on the geographic proximity of observing stations and some application-driven measure of statistical similarity (in this case rank correlation) is described. The procedure is then applied to temperature and precipitation data from the United States (US) Historical Climatology Network. The resulting station groups provide some insight into the number of observation stations that are necessary to monitor adequately the climate of the US. Based on temperature data alone, a 287-station subset of the original 1145 sites would be adequate to account for 80% of the spatial variability in seasonal temperature across the US. Geographically the distribution of these stations would be relatively sparse in the centre of the country with higher station density along the East Coast and from the Rocky Mountains to the West Coast. Generally, the temperature clusters match the existing US climate divisions to some extent. To monitor adequately the spatial variability of precipitation, a network of similar size could be used. However, such a network would only account for 65% of the spatial variability in precipitation. In this case, fairly uniform station density is indicated across the country with the highest station density in Florida and the Dakotas. A similar number of stations, but with slightly different geographic groupings would be adequate to monitor precipitation and temperature simultaneously. Copyright © 2001 Royal Meteorological Society [source] When, in the context of drug design, can a fluorine atom successfully substitute a hydroxyl group?INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2002Marcin Hoffmann Abstract In this article, we deal with the question of whether a fluorine atom can substitute a hydroxyl group in such a way that will lead to a compound showing a desired biologic activity, that is, a potential new drug. It is obvious that a fluorine atom differs from a hydroxyl group, as it cannot donate hydrogen bonds. However, it can accept them. Moreover, both fluorine and oxygen are of similar size and are the most electronegative elements. Therefore, a fluorine atom is thought to be a good substitute for a hydroxyl group. However, it was shown that for conformationally labile aliphatic compounds a replacement of a hydroxyl by a fluorine increases conformational diversity, so the fluorine-containing aliphatic molecules are present in equilibrium at room temperature as a mixture of several different conformers. In contrast, for cyclic compounds the substitution of an OH group by an F atom does not much change shape and electrostatic potential around corresponding conformers. Moreover, these compounds are present in equilibrium at room temperature in aqueous solution as a mixture of the same most favored structures. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 [source] Bayesian inference strategies for the prediction of genetic merit using threshold models with an application to calving ease scores in Italian Piemontese cattleJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 4 2002K. Kizilkaya Summary First parity calving difficulty scores from Italian Piemontese cattle were analysed using a threshold mixed effects model. The model included the fixed effects of age of dam and sex of calf and their interaction and the random effects of sire, maternal grandsire, and herd-year-season. Covariances between sire and maternal grandsire effects were modelled using a numerator relationship matrix based on male ancestors. Field data consisted of 23 953 records collected between 1989 and 1998 from 4741 herd-year-seasons. Variance and covariance components were estimated using two alternative approximate marginal maximum likelihood (MML) methods, one based on expectation-maximization (EM) and the other based on Laplacian integration. Inferences were compared to those based on three separate runs or sequences of Markov Chain Monte Carlo (MCMC) sampling in order to assess the validity of approximate MML estimates derived from data with similar size and design structure. Point estimates of direct heritability were 0.24, 0.25 and 0.26 for EM, Laplacian and MCMC (posterior mean), respectively, whereas corresponding maternal heritability estimates were 0.10, 0.11 and 0.12, respectively. The covariance between additive direct and maternal effects was found to be not different from zero based on MCMC-derived confidence sets. The conventional joint modal estimates of sire effects and associated standard errors based on MML estimates of variance and covariance components differed little from the respective posterior means and standard deviations derived from MCMC. Therefore, there may be little need to pursue computation-intensive MCMC methods for inference on genetic parameters and genetic merits using conventional threshold sire and maternal grandsire models for large datasets on calving ease. Zusammenfassung Die Kalbeschwierigkeiten bei italienischen Piemonteser Erstkalbskühen wurden mittels eines gemischten Threshold Modells untersucht. Im Modell wurden die fixen Einflüsse vom Alter der Kuh und dem Geschlecht des Kalbes, der Interaktion zwischen beiden und die zufälligen Effekte des Großvaters der Mutter und der Herden-Jahr-Saisonklasse berücksichtigt. Die Kovarianz zwischen dem Vater der Kuh und dem Großvater der Mutter wurde über die nur auf väterlicher Verwandtschaft basierenden Verwandtschaftsmatrix berücksichtigt. Es wurden insgesamt 23953 Datensätze aus den Jahren 1989 bis 1998 von 4741 Herden-Jahr-Saisonklassen ausgewertet. Die Varianz- und Kovarianzkomponenten wurden mittels zweier verschiedener approximativer marginal Maximum Likelihood (MML) Methoden geschätzt, die erste basierend auf Expectation-Maximierung (EM) und die zweite auf Laplacian Integration. Rückschlüsse wurden verglichen mit solchen, basierend auf drei einzelne Läufe oder Sequenzen von Markov Chain Monte Carlo (MCMC) Stichproben, um die Gültigkeit der approximativen MML Schätzer aus Daten mit ähnlicher Größe und Struktur zu prüfen. Die Punktschätzer der direkten Heritabilität lagen bei 0,24; 0,25 und 0,26 für EM, Laplacian und MCMC (Posterior Mean), während die entsprechenden maternalen Heritabilitäten bei 0,10, 0,11 und 0,12 lagen. Die Kovarianz zwischen dem direkten additiven und dem maternalen Effekt wurden als nicht von Null verschieden geschätzt, basierend auf MCMC abgeleiteten Konfidenzintervallen. Die konventionellen Schätzer der Vatereffekte und deren Standardfehler aus den MML-Schätzungen der Varianz- und Kovarianzkomponenten differieren leicht von denen aus der MCMC Analyse. Daraus folgend besteht wenig Bedarf die rechenintensiven MCMC-Methoden anzuwenden, um genetische Parameter und den genetischen Erfolg zu schätzen, wenn konventionelle Threshold Modelle für große Datensätze mit Vätern und mütterlichen Großvätern mit Kalbeschwierigkeiten genutzt werden. [source] Influence of maternal mass and condition on energy transfer in Weddell sealsJOURNAL OF ANIMAL ECOLOGY, Issue 3 2006KATHRYN E. WHEATLEY Summary 1Environmental variation influences food abundance and availability, which is reflected in the reproductive success of top predators. We examined maternal expenditure, offspring mass and condition for Weddell seals in 2 years when individuals exhibited marked differences in these traits. 2For females weighing 355 kg there was a positive relationship between maternal post-partum mass (MPPM) and lactation length, but below this there was no relationship, suggesting that heavier females were able to increase lactation length but lighter females were restricted to a minimum lactation period of 33 days. 3Overall, females were heavier in 2002, but in 2003 shorter females were lighter than similar-sized females in 2002 suggesting that the effects of environmental variability on foraging success and condition are more pronounced in smaller individuals. 4There was no relationship between MPPM and pup birth mass, indicating pre-partum investment did not differ between years. However, there was a positive relationship between MPPM and pup mass gain. Mass and energy transfer efficiency were 10·2 and 5·4% higher in 2002 than 2003, which suggests costs associated with a putatively poor-resource year were delayed until lactation. 5Heavier females lost a higher proportion of mass during lactation in both years, so smaller females may not have been able to provide more to their offspring to wean a pup of similar size to larger females. 6MPPM had only a small influence on total body lipid; therefore, regardless of mass, females had the same relative body composition. Females with male pups lost a higher percentage of lipid than those with female pups, but by the end of lactation female pups had 4·5% higher lipid content than males. 7It appears that for Weddell seals the consequences of environmentally induced variation in food availability are manifested in differences in maternal mass and expenditure during lactation. These differences translate to changes in pup mass and condition at weaning with potential consequences for future survival and recruitment. [source] Parasitism and developmental plasticity in Alpine swift nestlingsJOURNAL OF ANIMAL ECOLOGY, Issue 4 2003Pierre Bize Summary 1Development plasticity is a common evolutionary and phenotypic response to poor growth condition, in particular in organisms with determinate growth such as most birds and mammals. Because various body structures can contribute differently to overall fitness, natural selection will adjust the degree of plasticity of each structure to its proportionate contribution to fitness at a given life stage. 2Two non-mutually exclusive mechanisms can account for plasticity in the growth of offspring to compensate for the effect of parasites. First, if parasite infestation levels fluctuate over the nestling period, parasitized young may show reduced growth until peak parasite infestation, and accelerated growth once the conditions improve (the accelerated growth hypothesis). Secondly, if the period of tissue maturation is not fixed in time, hosts may grow slower than parasite-free hosts but for a longer period of time (the delayed maturation hypothesis). 3To test whether hosts compensate for the effects of parasites on their development, the load of the blood-sucking louse-fly Crataerina melbae Rondani in the nests of Alpine swifts, Apus melba Linnaeus, was increased or decreased experimentally. Parasite prevalence was 100% in both treatments, but intensity (no. of parasites per nestling) was significantly lower for deparasitized nestlings. In both treatments, parasite intensity increased up to halfway through the rearing period (i.e. 30 days of age) and decreased afterwards. 4In line with the accelerated growth hypothesis, wings of parasitized nestlings grew at a lower rate than those of deparasitized ones before the peak of parasite infestation, but at a greater rate after the peak. Louse-flies had no significant effect on the growth of body mass. In agreement with the delayed-maturation hypothesis, wings of parasitized nestlings grew for 3 additional days and were of similar size at fledging as in deparasitized birds. 5In summary, the present study shows in a wild bird population that nestling hosts can compensate for the effect of parasitism on their phenotype. It emphasizes the need to take the dynamics of parasite populations into account in studies of host,parasite relationships, and to investigate the effect of parasites on host development over the entire growing period rather than only at fledging, as employed traditionally. [source] Fast principal component analysis of large data sets based on information extractionJOURNAL OF CHEMOMETRICS, Issue 11 2002F. Vogt Abstract Principal component analysis (PCA) and principal component regression (PCR) are routinely used for calibration of measurement devices and for data evaluation. However, their use is hindered in some applications, e.g. hyperspectral imaging, by excessive data sets that imply unacceptable calculation time. This paper discusses a fast PCA achieved by a combination of data compression based on a wavelet transformation and a spectrum selection method prior to the PCA itself. The spectrum selection step can also be applied without previous data compression. The calculation speed increase is investigated based on original and compressed data sets, both simulated and measured. Two different data sets are used for assessment of the new approach. One set contains 65,536 synthetically generated spectra at four different noise levels with 256 measurement points each. Compared with the conventional PCA approach, these examples can be accelerated 20 times. Evaluation errors of the fast method were calculated and found to be comparable with those of the conventional approach. Four experimental spectra sets of similar size are also investigated. The novel method outperforms PCA in speed by factors of up to 12, depending on the data set. The principal components obtained by the novel algorithm show the same ability to model the measured spectra as the conventional time-consuming method. The acceleration factors also depend on the possible compression; in particular, if only a small compression is feasible, the acceleration lies purely with the novel spectrum selection step proposed in this paper. Copyright © 2002 John Wiley & Sons, Ltd. [source] Ab initio quality one-electron properties of large molecules: Development and testing of molecular tailoring approachJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 4 2003K. Babu Abstract The development of a linear-scaling method, viz. "molecular tailoring approach" with an emphasis on accurate computation of one-electron properties of large molecules is reported. This method is based on fragmenting the reference macromolecule into a number of small, overlapping molecules of similar size. The density matrix (DM) of the parent molecule is synthesized from the individual fragment DMs, computed separately at the Hartree,Fock (HF) level, and is used for property evaluation. In effect, this method reduces the O(N3) scaling order within HF theory to an n·O(N,3) one, where n is the number of fragments and N,, the average number of basis functions in the fragment molecules. An algorithm and a program in FORTRAN 90 have been developed for an automated fragmentation of large molecular systems. One-electron properties such as the molecular electrostatic potential, molecular electron density along with their topography, as well as the dipole moment are computed using this approach for medium and large test chemical systems of varying nature (tocopherol, a model polypeptide and a silicious zeolite). The results are compared qualitatively and quantitatively with the corresponding actual ones for some cases. This method is also extended to obtain MP2 level DMs and electronic properties of large systems and found to be equally successful. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 484,495, 2003 [source] Life history, ecology and longevity in batsAGING CELL, Issue 2 2002Gerald S. Wilkinson Summary The evolutionary theory of aging predicts that life span should decrease in response to the amount of mortality caused by extrinsic sources. Using this prediction, we selected six life history and ecological factors to use in a comparative analysis of longevity among 64 bat species. On average, the maximum recorded life span of a bat is 3.5 times greater than a non-flying placental mammal of similar size. Records of individuals surviving more than 30 years in the wild now exist for five species. Univariate and multivariate analyses of species data, as well as of phylogenetically independent contrasts obtained using a supertree of Chiroptera, reveal that bat life span significantly increases with hibernation, body mass and occasional cave use, but decreases with reproductive rate and is not influenced by diet, colony size or the source of the record. These results are largely consistent with extrinsic mortality risk acting as a determinant of bat longevity. Nevertheless, the strong association between life span and both reproductive rate and hibernation also suggests that bat longevity is strongly influenced by seasonal allocation of non-renewable resources to reproduction. We speculate that hibernation may provide a natural example of caloric restriction, which is known to increase longevity in other mammals. [source] Growth and reproductive biology of the foxfish Bodianus frenchii, a very long-lived and monandric protogynous hermaphroditic labridJOURNAL OF FISH BIOLOGY, Issue 3 2010S. Cossington Samples of the foxfish Bodianus frenchii, collected over reefs on the lower west and south coasts of Western Australia, contained individuals ranging up to 78 years old. Although B. frenchii is far smaller than many other species within the Labridae, its maximum age is the greatest yet recorded for this highly speciose family and, together with Achoerodus gouldii, provides an example of a temperate hypsigenyine with exceptional longevity. Length and age compositions of females and males and the histological characteristics of gonads of a wide length range of individuals demonstrated that B. frenchii is a protogynous hermaphrodite. Furthermore, as, on both coasts, the length of the smallest male was greater than that at which all females had become mature, B. frenchii is a monandric protogynous hermaphrodite, i.e. all of its males are derived from functional females. Attainment of maturity by females is related more to length than age, whereas the reverse is true for sex change. On the basis of Schnute growth equations and length-to-body mass regression equations, the predicted length at age and body mass at length of fish on the south coast were greater than those on the west coast throughout life. Although B. frenchii spawns daily during the main spawning season, which extends from October to February on both coasts, its fecundity at any given length is substantially greater on the south than on the west coast. The more rapid growth of juveniles and earlier attainment of maturity by B. frenchii on the south coast than on the warmer west coast, together with maturation at a similar size on both coasts, run counter to the trends observed in many species and certain ecological theories regarding the relationships between life-cycle traits and latitude and temperature. The attainment by B. frenchii of a larger body length at age, of greater body mass at length and of greater fecundity at both length and body mass in fish on the south than on the west coast strongly suggests that conditions on the former, cooler coast are more favourable for this labrid, which belongs to a sub-genus whose other species typically live in cool, deep, temperate waters. [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] Changes of taxonomic and trophic structure of fish assemblages along an environmental gradient in the Upper Beni watershed (Bolivia)JOURNAL OF FISH BIOLOGY, Issue 1 2006M. Pouilly The distribution and the diet of 28 fish species were evaluated, during the dry season, in 12 streams of the Upper Beni watershed (Amazon basin, Bolivia). The 12 streams were of similar size (stream width and water depth) but situated on a gradient of altitude in the Andean and sub-Andean areas. The environmental conditions in the stream changed in relation to the altitude. As altitude decreased, slope and water velocity also decreased, while temperature, conductivity, pH and the proportion of pools increased. Although the diets of the species were mainly based on two aquatic autochthonous food resources, invertebrates and sediment, species were classified into five trophic guilds: detritivores, algivores, piscivores, invertivores-omnivores and aquatic specialist invertivores. In all streams invertivores dominated or co-dominated with detritivores. The trophic structure of the assemblages, however, changed in relation to the environmental gradient. The fish species richness increased and the trophic composition became more diverse at lower altitudes, when slope decreased and temperature increased. At the same time, the relative number of invertivore species decreased, whereas the relative number of detritivore, algivore and piscivore species increased. Decreasing altitude appeared to play a role similar to increasing stream size along the longitudinal gradient. This could be explained by geomorphological and temperature variations that may generate environmental conditions favourable to an increase of productivity. [source] Nonexercise activity thermogenesis , liberating the life-forceJOURNAL OF INTERNAL MEDICINE, Issue 3 2007J. A. Levine Abstract Obesity occurs when energy intake exceeds energy expenditure over a protracted period of time. The energy expenditure associated with everyday activity is called NEAT (Nonexercise activity thermogenesis). NEAT varies between two people of similar size by 2000 kcal day,1 because of people's different occupations and leisure-time activities. Data support the central hypothesis that NEAT is pivotal in the regulation of human energy expenditure and body weight regulation and that NEAT is important for understanding the cause and effective treatment for obesity. [source] Probing the limits of molecular imprinting: strategies with a template of limited size and functionalityJOURNAL OF MOLECULAR RECOGNITION, Issue 1 2009Miruna Petcu Abstract A series of polymers molecularly imprinted with the general anaesthetic propofol were synthesized using both semi- and non-covalent approaches. The polymers were evaluated with respect to template rebinding in both aqueous and organic media. In aqueous media, the observed propofol binding in these polymer systems was largely hydrophobic and non-specific in nature. In non-polar solvents such as hexane, electrostatic (hydrogen bonding) interactions dominate resulting in some selectivity. The implication of these results, in conjunction with those obtained using structures of similar size in other studies, is that propofol, a template possessing limited functionality and size, appears to define the lower limit for template size and degree of functionalization that can be used for the creation of ligand-selective recognition sites in molecularly imprinted polymers. Furthermore, studies with alternative ligands indicate that the steric crowding of a ligand's functionality to the polymer contributes to the extent of polymer,ligand recognition. Copyright © 2008 John Wiley & Sons, Ltd. [source] Surface-enhanced Raman scattering spectroscopy via gold nanostarsJOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2009E. Nalbant Esenturk Abstract Anisotropic metallic nanoparticles (NPs) have unique optical properties, which lend them to applications such as surface-enhanced Raman scattering (SERS) spectroscopy. Star-shaped gold (Au) NPs were prepared in aqueous solutions by the seed-mediated growth method and tested for Raman enhancement using 2-mercaptopyridine (2-MPy) and crystal violet (CV) probing molecules. For both molecules, the SERS activity of the nanostars was notably stronger than that of the spherical Au NPs of similar size. The Raman enhancement factors (EFs) for 2-MPy on Au nanostars and nanorods are comparable and estimated as greater than 5 orders of magnitude. However, the enhancement for CV on nanostars was significantly higher than for nanorods, in particular at CV concentrations of 100 nM or lower. This article is a US Government work and is in the public domain in the USA. Published in 2008 by John Wiley & Sons, Ltd. [source] Use of endogenous ACTH concentration and adrenal ultrasonography to distinguish the cause of canine hyperadrenocorticismJOURNAL OF SMALL ANIMAL PRACTICE, Issue 3 2001S. M. Gould Twenty-nine dogs were diagnosed with hyperadrenocorticism (HAC). A single determination of endogenous plasma adrenocorticotropic hormone (ACTH) and adrenal ultrasonography were used in a prospective study to differentiate between pituitary-dependent HAC (PDH) and adrenal-dependent HAC (ADH). In 27 out of the 29 dogs (93 per cent), both endogenous plasma ACTH concentrations and adrenal ultrasonography indicated the same cause of HAC. Twenty-one of the 29 cases (72 per cent) were shown to be pituitary-dependent; all had plasma ACTH concentrations of greater than 28 pg/ml (reference range 13 to 46 pg/ml) and both adrenal glands were ultrasonographically of similar size and of normal shape. All 21 cases responded well to mitotane therapy. Six cases (21 per cent) were shown to be adrenal-dependent; all had plasma ACTH concentrations below the limit of the assay (<5 pg/ml) and the presence of an adrenal mass on ultrasonography. The sensitivity and specificity of adrenal ultrasonography and endogenous ACTH determinations to identify the cause of HAC were demonstrated to be 100 per cent and 95 per cent, respectively, for ADH. These discriminatory tests are more accurate than published figures for dexamethasone suppression testing. [source] ORAL SIZE PERCEPTION OF PARTICLES: EFFECT OF SIZE, TYPE, VISCOSITY AND METHODJOURNAL OF TEXTURE STUDIES, Issue 4 2005LINA ENGELEN ABSTRACT We investigated how different parameters affect oral size perception of small particles of SiO2 and polystyrene particles of varying sizes (2,230 ,m). Eighteen healthy subjects assessed the size of the particles by rubbing the sample between the tongue and the palate. The importance of size and type were studied by direct scaling and forced choice ranking and the results of the two methods were compared. To assess the relative importance of the tongue and the palate in oral size perception topical anesthesia was applied. The size and characteristics of particles are of importance for perception of particle size, where hard and irregular particles are perceived as larger than soft and round particles of similar size. The two methods of size perception, direct scaling and forced ranking produce very similar results on oral size perception. Topical anesthesia of either the tongue or the palate had no significant effect. [source] Bed Stability and Sedimentation Associated With Human Disturbances in Pacific Northwest Streams,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2009Philip R. Kaufmann Abstract:, To evaluate anthropogenic sedimentation in United States (U.S.) Pacific Northwest coastal streams, we applied an index of relative bed stability (LRBS*) to summer low flow survey data collected using the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program field methods in a probability sample of 101 wadeable stream reaches. LRBS* is the log of the ratio of bed surface geometric mean particle diameter (Dgm) to critical diameter (D*cbf) at bankfull flow, based on a modified Shield's criterion for incipient motion. We used a formulation of LRBS* that explicitly accounts for reductions in bed shear stress that result from channel form roughness due to pools and wood. LRBS* ranged from ,1.9 to +0.5 in streams within the lower quartile of human riparian and basin disturbance, and was substantially lower (,4.2 to ,1.1) in streams within the upper quartile of human disturbance. Modeling results suggest that the expected range of LRBS* in streams without human disturbances in this region might be generally between ,0.7 and +0.5 in either sedimentary or volcanic lithology. However, streams draining relatively soft, erodible sedimentary lithology showed greater reductions in LRBS* associated with disturbance than did those having harder, more resistant volcanic (basalt) lithology with similar levels of basin and riparian disturbance. At any given level of disturbance, smaller streams had lower LRBS* than those with larger drainages. In sedimentary lithology (sandstone and siltstone), high-gradient streams had higher LRBS* than did low-gradient streams of the same size and level of human disturbance. High gradient streams in volcanic lithology, in contrast, had lower LRBS* than low-gradient streams of similar size and disturbance. Correlations between Dgm and land disturbance were stronger than those observed between D*cbf and land disturbance. This pattern suggests that land use has augmented sediment supplies and increased streambed fine sediments in the most disturbed streams. However, we also show evidence that some of the apparent reductions in LRBS*, particularly in steep streams draining small volcanic drainages, may have resulted in part from anthropogenic increases in bed shear stress. The synoptic survey methods and designs we use appear adequate to evaluate regional patterns in bed stability and sedimentation and their general relationship to human disturbances. More precise field measurements of channel slope, cross-section geometry, and bed surface particle size would be required to use LRBS* in applications requiring a higher degree of accuracy and precision, such as site-specific assessments at individual streams. [source] Partitioning of metabolizable energy intake in sucking altricial and precocial rodent pupsJOURNAL OF ZOOLOGY, Issue 4 2006M. Kam Abstract We partitioned the metabolizable energy intake (MEI) into energy for maintenance (MEm) and for growth (MEg) in sucking precocial and altricial rodent pups. Each of the two components includes energy loss due to the heat increment of feeding. MEm of precocial pups expressed as average daily energy costs or as a proportion of MEI was greater than in altricial pups of similar size and, therefore, less energy was available for growth. Consequently, the overall energy cost (via total MEI) per unit postnatal growth of precocial pups was greater than for altricial pups of similar size. We used the proportion of calculated MEm to that predicted by body mass as an index of precociality in rodent pups. The proportion of MEg to MEI in precocial pups was lower than in altricial pups and was inversely related to the index of precociality. [source] Interaction of live and dead Escherichia coli O157:H7 and fluorescent microspheres with lettuce tissue suggests bacterial processes do not mediate adherenceLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2006E.B. Solomon Abstract Aims:, The goal of this study was to determine whether any specific bacterial processes (biochemical or genetic) or cell surface moieties were required for the interaction between Escherichia coli O157:H7 and lettuce plant tissue. Methods and Results:,Escherichia coli O157:H7 and FluospheresTM (fluorescent polystyrene microspheres) were used in experiments to investigate interactions with lettuce. FluospheresTM were used as they are a nonbiological material, of similar size and shape to a bacterial cell, but lack bacterial cell surface moieties and the ability to respond genetically. Live and glutaraldehyde-killed E. coli O157:H7 attached at levels of c. 5·8 log10 cells per cm2 following immersion of lettuce pieces into a suspension containing c. 8 log10 CFU ml,1. In a separate experiment, numbers of bacteria or FluospheresTM associated with lettuce decreased by c. 1·5 log cm,2 following a 1-min wash. Exposure times of 1 min, 1 h, or 6 h had little effect on the level of attachment for FluospheresTM, and live or killed cells of E. coli O157:H7 to lettuce tissue. Significance:, These results indicate that bacterial processes and cell surface moieties are not required for the initial interaction of E. coli O157:H7 to lettuce plant tissue. [source] Cellular morphology of rough forms of Listeria monocytogenes isolated from clinical and food samplesLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2000N.J. Rowan Transmission electron microscopy (TEM) studies revealed that rough cell-forms of L. monocytogenes (designated FR variants), isolated from clinical and food samples (and under conditions of sublethal heat stress), consist of either single or paired long-filaments. These FR variants markedly contrast in cell morphology from other previously described avirulent rough-mutants of L. monocytogenes that form long chains consisting of multiple cells of similar size (designated MCR variants). The identity of these Listeria isolates was determined using a commercially available, anti- Listeria polyclonal KPL antibody and by the API Listeria biochemical gallery. This study shows that filamentous rough-forms of L. monocytogenes may occur in clinical and food samples that are of undetermined pathogenicity. [source] Human and other faeces as breeding media of the trachoma vector Musca sorbensMEDICAL AND VETERINARY ENTOMOLOGY, Issue 3 2001P. M. Emerson Abstract. The fly Musca sorbens Wiedemann (Diptera: Muscidae) apparently transmits Chlamydia trachomatis, causing human trachoma. The literature indicates that M. sorbens breeds predominantly in isolated human faeces on the soil surface, but not in covered pit latrines. We sought to identify breeding media of M. sorbens in a rural Gambian village endemic for trachoma. Test breeding media were presented for oviposition on soil-filled buckets and monitored for adult emergence. Musca sorbens emerged from human (6/9 trials), calf (3/9), cow (3/9), dog (2/9) and goat (1/9) faeces, but not from horse faeces, composting kitchen scraps or a soil control (0/9 of each). After adjusting for mass of medium, the greatest number of flies emerged from human faeces (1426 flies/kg). Median time for emergence was 9 (inter quartile range = 8,9.75) days post-oviposition. Of all flies emerging from faeces 81% were M. sorbens. Male and female flies emerging from human faeces were significantly larger than those from other media, suggesting that they would be more fecund and live longer than smaller flies from other sources. Female flies caught from children's eyes were of a similar size to those from human faeces, but significantly larger than those from other media. We consider that human faeces are the best larval medium for M. sorbens, although some breeding also occurs in animal faeces. Removal of human faeces from the environment, through the provision of basic sanitation, is likely to greatly reduce fly density, eye contact and hence trachoma transmission, but if faeces of other animals are present M. sorbens will persist. [source] A study of candidate marine target impact craters in Arabia Terra, MarsMETEORITICS & PLANETARY SCIENCE, Issue 6 2010Germari de VILLIERS Arabia Terra is a region on Mars that straddles the crustal dichotomy, and several proposed shorelines are located in the area. Shallow marine impact craters on Mars likely would exhibit features like those on Earth, including characteristic morphological features that are distinctly different from that of craters formed on land. Common attributes of terrestrial marine impact craters include features of wet mass movement such as gravity slumps and debris flows; radial gullies leading into the crater depression; resurge deposits and blocks of dislocated materials; crater rim collapse or breaching of the crater wall; a central peak terrace or peak ring terrace; and subdued topography (an indicator of both age and possible flood inundation immediately following impact). In this article, these features have been used to evaluate craters on Mars as to a possible marine origin. This study used a simple quantification system to approximately judge and rank shallow marine impact crater candidates based on features observed in terrestrial analogs. Based on the quantification system, 77 potential shallow marine impact craters were found within an area bounded by 20°N and 40°N as well as 20°W and 20°E. Nine exemplary candidates were ranked with total scores of 70% or more. In a second, smaller study area, impact craters of approximately similar size and age were evaluated as a comparison and average total scores are 35%, indicating that there is some morphological difference between craters inside and outside the proposed shorelines. Results of this type of study are useful in helping to develop a general means of classification and characterization of potential marine craters. [source] | ||||||||||||||||||||||||||||||||||||||||