bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Light and Food on Larval American Lobsters, Homarus americanus
Authors: Eagles M. D. , Aiken D. E. , Waddy S. L.
Published: February 2009

Survival, size, and rate of development of larval American lobsters, Homarus americanus, to fourth stage are correlated postively with food quality. High survival requires that first-stage larvae encounter an abundance of food. Larval survival was higher in low light intensity than in a higher intensity that was well below that of full sunlight. Larvae reared on LD 12:12 photoperiods molted to the fourth stage predominantly during the dark phase, even when the timing of the light and dark phases was reversed. Larvae reared in continuous darkness developed faster and were almost twice the weight of larvae reared in a LD 12:12 photoperiod, but fewer survived to fourth stage.
Nutritional and Bioenergetic Considerations in the Development of the American LobsterHomarus americanus
Authors: Sasaki Glenn C. , Capuzzo Judith McDowell , Biesiot Patricia
Published: February 2009

To better understand the early life history stages of the American lobster Homarus americanus, nutritional and bioenergetic aspects of development have been investigated. These studies focused on physiological and biochemical processes during transitional periods between extrusion of the eggs, hatching, larval development, molting, metamorphosis, and attainment of the juvenile stage. Biochemical changes during embryogenesis reflect catabolism of various substrates for energy. Exposure to different thermal regimes resulted in considerable variation in the rates of utilization of energy substrates during embryogenesis. Embryos raised at elevated temperatures had yolk remaining at the time of hatching. The first three larval stages have similar energy requirements. Lipid is of prime importance and the turnover rate for lipid can be rapid. Weight-specific metabolism increases with successive larval stages, in stage IV lobsters, the dependency on lipid as a substrate is diminished and lipid reserves serve a storage function. Metabolic rates of premolt stage IV lobsters are decreased in comparison with earlier stages. These changes in physiology correlate with changes in the developing midgut gland, specifically with the appearance of droplets of lipid in the lipid-storing cells of the midgut gland of stage IV lobsters. By stage VI, lobsters have energy storage and metabolic patterns similar to those of adults, and the midgut gland has the adult morphology. The transitions from hatching to attainment of the juvenile form are reflected in differences in physiological and biochemical processes that influence food selection and diet.
Recruitment Dynamics in an American Lobster (Homarus americanus) Population
Authors: Fogarty Michael J. , Idoine Josef S.
Published: February 2009

We examined relationships between successive life history stages of an American lobster (Homarus americanus) population for evidence of density-dependent control. Analysis of a time series of larval production estimates for the Northumberland Strait region of the southern Gulf of St. Lawrence during 1949–63 (D. J. Scarratt. 1964. J. Fish. Res. Board Can. 21: 661–680; D. J. Scarratt. 1973. J. Fish. Res. Board Can. 30: 1819–1824) provided no indication of density-dependent regulation during the pelagic larval phase. However, an asymptotic relationship between the final (fourth) larval stage and stock size 5–7 yr later was demonstrated, indicating the possibility of density-dependent regulation between larval settlement and subsequent recruitment to the fishery. A second analysis supported these results based on trends in population size over several generations. A recruitment mechanism of this type is highly stabilizing and can explain the apparent capacity of lobster populations to sustain high levels of fishing mortality. The postulated recruitment mechanism for Northumberland Strait lobsters may reflect competition for critical resources. We propose that shelter is an important limiting resource and that shelter competition experiments be undertaken in the field and laboratory to test this hypothesis. Finally, we demonstrate the use of a multistage recruitment model which accounts for the general form of observed interstage relationships. The asymptotic relationship between stage IV production and subsequent stock results in a stable population which is resilient to exploitation.
Reappearance of Spawning Atlantic Herring (Clupea harengus harengus) on Georges Bank: Population Resurgence not Recolonization
Authors: Stephenson Robert L. , Kornfield Irv
Published: February 2009

Spawning Atlantic herring (Clupea harengus harengus L.) have been recorded on Georges Bank for the first time since the collapse in 1977 of what had once been the largest herring fishery in the Northwest Atlantic. The reappearance after almost a decade could have resulted from resurgence of a residual extant Georges Bank population or from recolonization by fish from neighboring spawning groups. Three independent lines of evidence are consistent with the resurgence hypothesis: the Georges bank fish differed in age composition and isozyme characteristics from neighboring populations, and the reappearance was later than expected for recolonization. The degree of isozyme variability and of mitochondrial DNA lineage diversity gave no indication that stochastic events influenced the genetic structure of the herring population at Georges Bank after the collapse. The persistence of this population, in spite of considerable potential for recolonization, supports the discrete population concept in herring.
Effect of Climatic Warming on the Southern Margins of the Native Range of Brook Trout, Salvelinus fontinalis
Authors: Meisner J. Donald
Published: February 2009

Stream inventories of brook trout (Salvelinus fontinalis) habitat show that the minimum altitude of a brook trout stream in the southern part of the native range rises steadily from sea level at about 39° 12′N, to approximately 640 m at about 34° 40′N at the southern margin of the range. Using this empirical lower stream boundary and a statistical model of the influence of altitude and latitude on groundwater temperature, I suggest that the lower altitudinal margin of the southern part of the native range is shaped by the 15 °C groundwater isotherm. I used the climate warming scenario of the Goddard Institute for Space Studies, GISS, to estimate the increase in groundwater temperature in the native brook trout range, and to estimate the increase in the altitude of the lower stream boundary in a "warmer" climate. The GISS scenario projects a 3.8 °C increase in mean annual air temperature for the southern part of the native brook trout range in the next century, which leads to increases of up to 714 m in the altitude of the lower stream boundary, and to significant reductions in area available for brook trout.
Phosphorus Deficiency and its Variation among Lakes
Authors: Currie David J.
Published: February 2009

The severity of phosphorus deficiency varies greatly among lakes. Is this variation related to particular morphological, chemical, or biological characteristics of lakes? These questions were addressed by sampling 49 lakes in Quebec, Ontario, and the northeastern United States. The rate constant of orthophosphate uptake (k1), a measure of orthophosphate demand:supply, proved to be only weakly related to watershed area and to the total phosphorus (P) concentration of the water (R2 = 0.210). Abundance of the biota and other aspects of water chemistry were all unrelated to the intensity of P-deficiency as it varies among lakes. In contrast, within-lake seasonal variability of the rate constant of orthophosphate turnover (kt, which is approximately equal to k1) is strongly related to temperature and bacterial abundance (R2 = 0.575 to 0.828). The results indicate that the seasonal variation in phosphorus deficiency depends strongly on bacterioplankton activity, whereas inter-lake variability in phosphorus deficiency is determined mainly by factors other than morphometry, plankton abundance, or trophic richness.
Comparison of Zygnematacean (Chlorophyta) Algae in the Metaphyton of Two Acidic Lakes
Authors: Howell E. T. , Turner M. A. , France R. L. , Jackson M. B. , Stokes P. M.
Published: February 2009

In 1986, Plastic Lake (pH≈5.6), acidified by acidic precipitation, and L.302S (pH≈5.0), experimentally acidified by addition of H2SO4, showed similar patterns of unattached benthic growth (metaphyton) of filamentous green algae. The mid to late summer build-up of metaphyton was extensive in both lakes, affecting nearly 100% of the lake perimeters, being concentrated in a shallow band 0.5–1.0 m deep in L.302S and 0.4–2.7 m deep in Plastic Lake. Distribution was negatively related to depth and bottom slope but independent of type of substratum. The areal density of metaphyton in the 0–2 m depth zone of Plastic Lake was estimated to be 1.2 g dry weight (dw)∙m−2. The productivity of metaphyton standardized by biomass was inversely related to the concentration of algae incubated. Over a common range of incubation concentrations primary production rates were similar in L.302S and Plastic Lake (≈1.6 μg C (mg dw)−1∙h−1) despite differences in the composition of the communities, predominately Mougeotia sp. and Spirogyra sp. in L.302S, and Zygogonium tunetanum Gauthier-Lievre in Plastic Lake.
Allozyme and Mitochondrial DNA Variation among Three Species of Stizostedion (Percidae): Phylogenetic and Zoogeographical Implications
Authors: Billington Neil , Hebert Paul D. N. , Ward Robert D.
Published: February 2009

The percid genus Stizostedion consists of five species, three in Europe and two in North America, and is believed to have evolved in Europe and then later colonized North America. Three hypotheses exist concerning the route and timing of this colonization: a Miocene Atlantic "riverine" route; a Pliocene Beringian route; and a late-Pleistocene Atlantic route. To test these hypotheses, allozyme and mitochondrial DNA variation were compared in three Stizostedion species, S. canadense and S. vitreum from North America, and S. lucioperca from Europe, to determine their genetic relatedness. Divergence times between S. canadense and S. vitreum were estimated as 3.12 ± 1.33 million years before present (MYBP) from allozyme data and 4.06 ± 0.73 MYBP for mtDNA data, while divergence times between the North American species and S. lucioperca were 10.59 ± 2.74 MYBP and 7.86 ± 1.18 MYBP, respectively. These results are concordant with the hypothesis that colonization of North America by Stizostedion occurred during the Pliocene via Beringia.
Reduced Catch of Under-Sized Cod (Gadus morhua) in Longlining by Using Artificial Bait
Authors: Løkkeborg Svein
Published: February 2009

Three sizes of artificial bait incorporating shrimp flavour into polyurethane foam were compared with natural shrimp bait of the size used in commercial longlining. Fishing trials were conducted during the spring fishery for Atlantic cod (Gadus morhua) off the coast of Northern Norway. The small artificial bait gave almost the same catch rate as natural shrimp bait, whereas artificial baits of larger sizes compared poorly. The length distribution of the catch was influenced by both bait type and bait size. Fewer small cod were caught on the artificial baits. There was no difference in the number of large cod. Mean cod length was therefore higher on the artificial baits and increasing the artificial bait size accentuated the difference. These effects are explained by different preferences with regard to prey species and size between small and large cod. The size selective effects of bait type and bait size are discussed in relation to conservation aspects.
Weighted Multicollinearity in Logistic Regression: Diagnostics and Biased Estimation Techniques with an Example from Lake Acidification
Authors: Marx Brian D. , Smith Eric P.
Published: February 2009

An historical data set from the Adirondack region of New York is revisited to study the relationship between water chemistry variables associated with acid precipitation and the presence/absence of brook trout (Salvelinus fontinalis) and lake trout (Salvelinus namaycush). For the trout species data sets, water chemistry variables associated with acid precipitation, for example pH and alkalinity, are highly correlated. Regression models to assess their effects on the probability of the presence of fish species are therefore affected by multicollinearity. Because the appropriate regressions are logistic, correction techniques based on least squares do not work. Maximum likelihood parameter estimation is highly unstable for the trout presence/absence data. Developments in weighted multicollinearity diagnostics are used to evaluate maximum likelihood logistic regression parameter estimates. Further, an application of biased parameter estimation is presented as an option to the traditional maximum likelihood logistic regression. Biased estimation methods, like ridge, principal component, or Stein estimation can substantially reduce the variance of the parameter estimates and prediction variance for certain future observations. In many cases, only a slight modification to the converged maximum likelihood estimator is necessary.
Smolting Status of Downstream Migrating Atlantic Salmon (Salmo salar) Parr
Authors: Birt Tim P. , Green John M. , Davidson William S.
Published: February 2009

Significant numbers of Atlantic salmon (Salmo salar) parr have been observed to accompany seaward migrating smolts in some rivers. Downstream migrating parr in Freshwater River Newfoundland, have lower salinity tolerance and branchial Na+–K+ ATPase activity than smolts. However, moisture content in downstream migrating parr was similar to that of smolts; both groups had higher mean moisture content than nonmigratory parr. Mean plasma sodium concentration was significantly higher than in smolts, but somewhat lower than in nonmigratory parr. Elevated moisture levels and slightly depressed plasma sodium concentrations are consistent with the view that seaward movement is associated with osmoregulatory imbalance in both parr and smolts. Brackish water found in estuaries appears important for gradual development of salinity tolerance in these migrants.
Use of a General Dose–Response Model for Rockfish Fecundity–Length Relationships
Authors: Richards Laura J. , Schnute Jon T.
Published: February 2009

In this paper we describe a general method for determining the relationship between fecundity and another fish attribute, such as size or age. Our methods include linear and logarithmic regression models as special cases and are applicable to a wide range of situations. The model we propose is based on the univariate form of the Schnute–Jensen dose–response model. However, we extend the Schnute–Jensen analysis by describing exact inference regions obtained from likelihood contours, to which we assign nominal probability levels. We also provide a method for obtaining an inference band for the predicted curve. We examine the issue of model adequacy as it relates to fecundity–length data from two rockfish (Sebastes) species. We show that the extra complexity of our model is justified, as none of the traditional regression models are appropriate for all three of our data sets. Further, we use inference bands to distinguish fecundity–length relationships for quillback rockfish (S. maliger) from two areas, but we are unable to distinguish one of these relationships from a similar relationship for copper rockfish (S. caurinus).
The Lobster (Homarus americanus) Fishery off Lower Argyle Southwestern Nova Scotia
Authors: Campbell Alan
Published: February 2009

Catch and effort data for the lobster (Homarus americanus) fishery of Lower Argyle, Nova Scotia, were obtained from sales slips on a weekly basis during 1978–87. Lobster size–frequency distributions were collected during at-sea sampling at the beginning and end of each fishing season. This fishery experienced a three-fold increase in landings (from 87.6 to 270 t) due to an increase in recruitment during the 10-yr study. The fishermen responded to the improved recruitment by increasing the total number of days fished per season by 41%. Overall mortality of recruited lobster (estimated from size–frequencies) rose from 55% in 1978 to 72–81% during 1985–87. During the 1987–88 fishing season, about 1 t lobster were removed per km2 of fishing grounds. Regression relationships between a prerecruit juvenile abundance index (numbers of lobster/trap haul) and the recruited yield one to two fishing seasons later were significantly correlated for 8–9 yr of data; equations predicted that lobster yields would remain high during the 1988–89 fishing season but decline in this area during 1989–90 fishing season. Management implications of forecasting recruitment yields 1–2 yr in advance and possible strategies to reduce major recruitment fluctuations in this fishery are discussed.
Ovulatory Rhythm and a Method to Determine the Stage of Spawning in Atlantic Cod (Gadus morhua)
Authors: Kjesbu O. S. , Witthames P. R. , Solemdal P. , WalKer M. Greer
Published: February 2009

The size frequency distribution of the vitellogenic oocytes in Atlantic cod (Gadus morhua) changes in a predictable manner as spawning progresses. This change was studied by sampling successive batches of eggs from reared cod kept in the laboratory. The shape of the vitellogenic oocyte mode was described by measuring the diameter, standard deviation, and skewness and kurtosis. Linear regressions were derived which related the portion of the total number of eggs spawned per season (PES) to the number of vitellogenic oocytes per gram of the ovary and in relation to the standard deviation of the distribution. This method which allows the PES in a spawning fish to be estimated has the following applications. For fish stock assessment purposes fecundity estimates can be made on spawning rather than prespawning fish and residence times on spawning grounds can be calculated. In addition successive batches of eggs can be identified and studied. This is important in hormonal and larval studies. A detailed description is given of the oocyte growth during the ovulatory rhythm. The rhythm consists of four periods: arrest, final growth, hydration, and ovulation. It is suggested that the egg size is determined during the final growth period.
Size-Structured Morality in a Treespine Stickleback (Gastrosteus aculeatus) – Cutthroat Trout (Oncorhynchus clarki) Community
Authors: Reimchen T. E.
Published: February 2009

In a 112-ha bog lake on the Queen Charlotte Islands, British Columbia, small fish comprised the major element in the diet of cutthroat trout (Oncorhynchus clarki). Despite the presence of juvenile salmon and char in the lake, threespine stickleback (Gasterosteus aculeatus) was the most common fish in the diet (99.5%). Foraging activity appeared to be more frequent in littoral than in limnetic regions. Mark–recapture methods indicate an average population of 220 trout and 75 000 adult stickleback. Trout consumed an estimated 308 770 stickleback yearly (145 kg) of which 65% were taken during summer. Seventy-three percent of all fish consumed were young of the year and 2% were adults, the latter representing 4% of the adult population in the lake. There was a 75% reduction in total mortality between successive year classes of stickleback (0,1,2,3 +). This consumption curve, which resembles a typical survivorship curve of fish, is a function of the size-structure of the populations and includes interactions between size availability of stickleback, prey-size preferences of the trout, and length frequency distributions of trout. Total weight of stickleback consumed by trout comprised about 40% of that previously calculated for 16 species of avian piscivores in the lake.
Estimating the Blubber Content of Phocid Seals
Authors: Ryg Morten , Lydersen Christian , Markussen Nina H. , Smith Thomas G. , Øritsland Nils Are
Published: February 2009

We have investigated the relationships between percent blubber content and xiphostemal blubber thickness or girth-to-length ratios in ringed seal (Phoca hispida), harp seal (Phoca groeniandica), and grey seal (Halichoerus grypus). The blubber content was significantly correlated with blubber depths and girth-to-length ratios in all three species, in addition, we have developed an estimator for percent blubber content (the LMD-index) based on standard length (L, in meters), body mass (M, in kilograms), and on blubber thickness (d, in meters) measured at a defined position dorsally. From these variables the percent blubber content (B%) can be estimated by the expression B% = 4.44 + 5693 [Formula: see text], with a standard error of the estimate of three percentage units. This index also gave reasonable estimates for blubber content in three harbour seals (Phoca vitulina) and eight bearded seals (Erignatus harbatus).
Relationship between Annual Recruitment and Density in a Lacustrine Population of Allopatric Brown Trout (Salmo trutta)
Authors: BorgstrØm Reidar
Published: February 2009

The annual recruitment of brown trout (Salmo trutta) parr from stream nursery areas to an allopatric, lake-resident population was studied during a 5-yr period. The immigration of each cohort to the lake occurred over several years, but the data indicate that the duration of the lotic residence of parr may be regulated by the density of the lake population. At high lake population density, the number of brown trout in age-class 3+ present in the lake by June was low, while at low lake population density the number of 3+ fish increased substantially.
Embryonic and Postembryonic Development in Bythotrephes cederstroemii
Authors: Yurista Peder M.
Published: February 2009

Laboratory observations were made of embryonic development time for parthenogenic Bythotrephes cederstroemii under differing temperatures spanning the range when Bythotrephes may be present in the plankton of Lake Michigan. Postembryonic development was documented for parthenogenically produced and sexually produced offspring. The complete life cycle of Bythotrephes was observed to have two distinct morphological series. Development time from birth to primaparity, consisting of three instars, was 14.0 ± 1.63 d at 12.7 °C for pathenogenically produced offspring. Development time at 12.7 °C for gametogenically produced offspring was 13.7 ± 1.57 d with four instars. Because parthenogenic eggs released into the brood sac of Bythotrephes do not become obvious until the embryo development is well advanced, a useful model for birth rate calculations in field work was developed based on observable morphological traits of the embryos within the brood sac. A curvilinear logarithmic model of development time (D, hours) as a function of temperature (T degrees Celsius) was fit to the embryonic development data: log (D) = 6.840–7.305log(T) + 2.490log(T)2.
Mollusk Shell Growth: External Microgrowth Ridge Formation is Uncoupled to Environmental Factors in Mytilus edulis
Authors: Bérard Hélène , Bourget Edwin , Fréchette Marcel
Published: February 2009

Low-frequency (e.g. annual) external ridges have been used in the study of bivalve population dynamics, and it has been suggested that ridges produced at high frequencies are related to environmental factors. Using laboratory and field experiments, we examined the usefulness of fine external growth ridges as markers of cyclic growth patterns in the blue mussel, Mytilus edulis. Shells of M. edulis were analyzed to examine coherence of patterns of ridges on the shells. Analysis was carried out in two steps: (1) An objective method was developed to characterize the ridges by their height and thickness (precision 0.5 μm) and (2) laboratory and field experiments were carried out to determine the influence of environmental factors (immersion and emersion, algal concentration) and biological factors (valve closure) on the periodicity of growth ridge formation. All mussels exhibited unique growth ridge patterns. There was no concordance between growth ridge patterns of individual mussels grown together in the laboratory or in the field. These results refute the hypothesis of a similar growth ridge pattern between individuals in Mytilus at small scales. No relation was found between the mechanical closure of the valves and the formation of growth ridges.
An Experimental Study of Piscivore–Planktivore Interactions: Population and Community Responses to Predation
Authors: He Xi , Wright Russell A.
Published: February 2009

The population dynamics and behavior of an assemblage of fishes in a small bog lake were studied in a succession of whole-lake manipulations of piscivores. Total prey fish biomass declined after the addition of northern pike (Esox lucius). This decline was the result of emigration by cyprinid prey and consumption by northern pike. The emigration response of the cyprinids was dependent on cyprinid density. At high prey fish biomass, a significant portion of the loss in biomass was the result of emigration; this was not the case at low prey fish biomass. The prey fish community shifted from small-bodied soft-rayed species prior to the introduction of northern pike to species with spines or deep bodies after predator stocking. The community response was analyzed at four levels of numerical resolution: absolute, relative, and ranked abundance and presence–absence of prey species. High numerical resolution captured the dynamic short-term population responses to predation and suggests unstable community structure.
Taxonomic Level Sufficient for Assessing a Moderate Impact on Macrobenthic Communities in Puget Sounds Washington, USA
Authors: Ferraro Steven P. , Cole Faith A.
Published: February 2009

Macrobenthic data obtained using three sampling schemes (0.06-m2 × 8-cm-deep sampling unit and 1.0- or 0.5-mm-mesh sieves, and 0.1-m2 × 8-cm-deep sampling unit and 1.0-mm-mesh sieve) previously identified as optimal or near-optimal for detecting differences between a reference and a moderately impacted station when animals were identified to species were reanalyzed at the genus, family, order, and phylum level to determine the taxonomic level sufficient to detect differences between the stations with t-tests on five measures of community structure. Taxonomically sufficient levels for number of taxa were family in 1.0-mm-mesh samples and species in 0.5-mm-mesh samples. Specific identification was usually required for a Dominance, Shannon's, 1 – Simpson's, and McIntosh's Index in 1.0- and 0.5-mm-mesh samples, suggesting limits to the utility of the taxonomic sufficiency concept when using those indices to detect moderate impacts. This and a previous study indicate that one could reliably [Formula: see text] detect moderate benthic impacts at the study site on number on taxa and five other measures of community structure with five to seven replicate 0.06-m2 × 8-cm-deep, 1.0-mm-mesh samples per station and identification to family only. Taxonomic sufficiency can vary depending upon the animal size fraction sampled and the measure used.
Morphology and Evolution of Salmonid Habitats in a Recently Deglaciated River Basin, Washington State, USA
Authors: Benda L. , Beechie T. J. , Wissmar R. C. , Johnson A.
Published: February 2009

Morphology and distribution of salmonid habitats were related to the geomorphology of a river basin at three spatial scales including reach (102–103 m2), subbasin (2–26 km2), and the watershed (240 km2). Stream reaches on a young fluvial terrace (1700 yr old) adjacent to the main river contain the most extensive areas of rearing and spawning habitats. In tributary subbasins, the area of spawning habitat varies according to discharge rates and channel gradients. The most extensive salmonid habitats are located along wide glacial deposits in geologically unconstrained areas of the main valley floor. During the early Holocene (~10 000 – 12 000 years before present (B.P.)), the recently deglaciated watershed of the South Fork Stillaguamish River was extremely erosive and vegetated by alpine forest. Fish habitats then were less suitable for salmonid rearing and spawning. A much lower erosion rate after 8000 yr B.P., and the advent of old growth conifer forests after 6000 yr B.P., indicates that stream habitats attained their present-day morphology between 8000 and 6000 yr ago. Although habitats increased in quality with increasing watershed stability and evolution of forests, they decreased in quantity after 7000 yr B.P as landforms changed because of continuous river incision into glacial deposits.
Food Limitation and Interspecific Competition in Snail-Dominated Streams
Authors: Hill Walter R.
Published: February 2009

Food limitation and exploitative competition were implicated in two experiments on lotic grazers in eastern Tennessee. In a laboratory feeding experiment, grazing snails (Elimia clavaeformis) and caddisfly larvae (Neophylax etnieri) from upper White Oak Creek (WOC) grew 7 and 2 times faster, respectively, on a diet of high-biomass periphyton than they did on a diet of WOC periphyton. When fed on the high-biomass periphyton, both grazers accumulated disproportionately more neutral lipid, and snails increased their mean condition index 50% (ash-free dry mass per unit wet mass). Growth and condition of grazers fed WOC periphyton in the laboratory were quite similar to growth and condition in situ, indicating that laboratory conditions were realistic. Analysis of gut contents demonstrated considerable dietary overlap between the two taxa regardless of periphyton diet and suggested that quantity rather than quality of periphyton limited grazer growth and condition in WOC. In a natural experiment, periphyton and Neophylax from six streams containing Elimia were compared with periphyton and Neophylax from six streams that lacked Elimia. Periphyton biomass, Neophylax diapause mass, and Neophylax lipid content were substantially greater in streams lacking Elimia, implying that the snail created or exacerbated food-limiting conditions for Neophylax.
Intrinsic and extrinsic sources of variation in the dynamics of large herbivore populations
Authors: Marshal J. P. , Cain J. W. , Bleich V. C. , Rosenstock S. S.
Published: February 2009

We evaluated the relative importance of intrinsic (density-dependent) and extrinsic (density-independent) sources of resource variability in the dynamics of bighorn sheep ( Ovis canadensis Shaw, 1804) populations in southwestern USA. We tested the hypothesis that populations experiencing greater variation in forage availability are less likely to be at equilibrium density with forage supplies, and thus, would demonstrate weaker evidence of intraspecific competition. We used regression to relate population growth rate to rainfall (forage conditions) and to abundance (intraspecific competition) for 20 sheep populations, and we estimated the strength of the effects of density and rainfall for each population. Then we compared among populations to look for relationships between the strengths of rainfall and density effects and the variability in rainfall experienced by each population. Populations demonstrating a density effect were associated with environments having lower variability than those that did not. Populations showing a rainfall effect were associated with environments having a variability higher than those that lacked a rainfall effect. These findings are consistent with the hypothesis that populations experiencing higher variation in forage resources are less likely to achieve an equilibrium density with forage supplies where intraspecific competition would be a large determinant to the dynamics of that population.
Effects of early growth conditions on body composition, allometry, and survival in the ladybird beetle Harmonia axyridis
Authors: Dmitriew C. , Carroll J. , Rowe L.
Published: February 2009

During both the larval and adult stages, the ladybird beetles Harmonia axyridis (Pallas, 1773) feed primarily on aphids, populations of which may fluctuate dramatically in time and space. Harmonia axyridis were reared under three resource treatments: high, low, and improving. We predicted that beetles experiencing consistently poor larval conditions would allocate limited resources to dispersal traits (by increasing relative wing surface area and fat storage), whereas larvae facing good or improving conditions were predicted to allocate preferentially to reproductive traits. As predicted, beetles reared at low food had lower wing loading and stored more fat than individuals reared at consistently high food. When conditions were initially poor but improved during development, body size was reduced relative to the high food treatment, though wing area scaled similarly. Allocation of fat and protein was dependent on both sex and treatment. Females in improving conditions stored less fat, and males less protein, relative to low food conditions. This is suggestive of a trade-off between reproduction and dispersal that is resolved differently between the sexes. Unexpectedly, adult survival under starvation was not appreciably affected by larval growth conditions, although males lived about 10 days longer, on average.
EXTENDED DOUBLE LINEAR SYSTEMS AND NEW INFINITE-DIMENSIONAL DOUBLE HIDDEN SYMMETRIES FOR STRING EFFECTIVE ACTION
Authors: GAO YA-JUN
Published: February 2009

Symmetries of the string effective action describing the coupled gravity, dilaton and Kalb–Ramond fields (called EDKR theory for brevity) are studied. A previously proposed extended double-complex method is used and some double structures of the dimensionally reduced (from (2+d)-dim to 2-dim) EDKR theory are found. A 2d × 2d matrix double-complex H-potential is constructed and the field equations are extended to a double-complex formulation. Moreover, a pair of extended double-complex Hauser–Ernst-type linear systems are established, and based on these linear systems, explicit formulations of new hidden double symmetry transformations for the EDKR theory are given. These symmetry transformations constitute double infinite-dimensional Lie algebras, each of which is a semidirect product of the Kac–Moody [Formula: see text] and Virasoro algebras (without center charges). These results demonstrate that the EDKR theory under consideration possesses richer symmetry structures than previously expected.
GAUGE DEPENDENCE OF FERMION MASS RENORMALIZATION PRESCRIPTIONS
Authors: ZHOU YONG
Published: February 2009

We discuss the gauge dependence of fermion mass definition under the on-shell and pole mass renormalization prescriptions. By the two-loop-level calculation of the cross section of the physical process [Formula: see text], we prove for the first time that the on-shell fermion mass renormalization prescription makes physical result gauge-dependent. On the other hand, such gauge dependence does not appear in the result of the pole mass renormalization prescription. Our calculation also implies that the difference of physical results between the two mass renormalization prescriptions cannot be neglected at two-loop level.
QUANTIZATION OF EXCITON IN MAGNETIC FIELD BACKGROUND
Authors: GIRI PULAK RANJAN , CHAKRABARTI S. K.
Published: February 2009

The possible mismatch between the theoretical and experimental absorption edge peaks in semiconductors in a magnetic field background may arise due to the approximation scheme used to analytically calculate the absorption coefficient. As a possible remedy we suggest to consider nontrivial boundary conditions on x–y plane by in-equivalently quantizing the exciton in background magnetic field. This inequivalent quantization is based on von Neumann's method of self-adjoint extension, which is characterized by a parameter Σ. We obtain bound state solution and scattering state solution, which in general depend upon the self-adjoint extension parameter Σ. The parameter Σ can be used to fine tune the optical absorption coefficient K(Σ) to match with the experiment.
TEXTURE CHARACTERIZATION USING WSFS AND WCFS
Authors: ARIVAZHAGAN S. , GANESAN L.
Published: February 2009

Texture analysis plays an important role in many tasks, ranging from remote sensing to medical imaging and query by content in large image data bases. The main difficulty of texture analysis in the past was the lack of adequate tools to characterize different scales of textures effectively. The development in multi-resolution analysis such as Gabor and wavelet transform help to overcome this difficulty. This paper describes the texture characterization system using (i) Wavelet Statistical Features (WSF) obtained from 3-level Discrete Wavelet Transformed (DWT) images, (ii) Wavelet Co-occurrence Features (WCF) of one level wavelet transformed images in detail.
REFERENCE-FREE MACHINE VISION INSPECTION OF SEMICONDUCTOR DIE IMAGES
Authors: NG ADA N. Y. , LAM EDMUND Y. , CHUNG RONALD , FUNG KENNETH S. M. , LEUNG W. H.
Published: February 2009

Advances in electronic technology have made integrated circuits (ICs) the fundamental components in all electronic devices. To increase their production yield by catching defects as early as possible, we need to perform quality assurance on the semiconductor dies during the assembly and packaging processes. A common approach is to employ machine vision to compare a test die with a "known good die". However, difficulties in ensuring identical imaging conditions (such as illumination) are limitations to this die-to-die comparison approach. Instead, in this work we develop a novel reference-free defect detection algorithm for an IC die by analyzing its image. By identifying intrinsic and extrinsic features of various segments in the image, we implement a classification scheme to identify whether the die is defective or not. We rely on the fact that normal ICs contain regular patterns, and the abnormal and irregular regions are classified as potential areas of defects. Experimental results show that the proposed reference-free defect detection algorithm can detect most of the defects from different types of IC dies, and can also correctly classify normal IC dies as non-defective. These results demonstrate the feasibility of the reference-free defect detection approach.
HIGH YIELD PREPARATION OF FULLERENE NANOWHISKERS AND NANOTUBES BY THE SOLUTION ROUTE
Authors: RINGOR CHERRY L. , MIYAZAWA KUN'ICHI
Published: February 2009

The effect of ultraviolet, visible and near-infrared irradiation on the yield and morphology of single crystalline C 60 fullerene nanowhiskers (FNWs) and nanotubes (FNTs) was investigated in an effort to produce large-scale quantities of FNWs and FNTs. These fullerene nanomaterials were synthesized by the liquid–liquid interfacial precipitation method using pyridine and isopropyl alcohol (IPA) as solvents. The C 60–pyridine solution was illuminated using different wavelengths for 24 h at ambient pressure and temperature before addition of IPA. High yields (30–38 mg/L) were obtained upon irradiation using wavelengths in the ultraviolet region in accordance with the increased photoabsorption signal of solid C 60 and C 60 dissolved in pyridine acquired by a UV-VIS-NIR spectrophotometer. However, elevated yields (21–27 mg/L) were also obtained in the 600–800 nm regions, where C 60 absorption is particularly weak. Such an enhanced yield of FNTs and FNWs is probably related to the reported rise in transient absorption of the triplet excited state of C 60 in the 740 nm region formed by the decay of the photoexcited singlet C 60 through intersystem crossing. The formation of photopolymerized fullerene nanofibers was also observed by Raman spectroscopy, it is attributed to ultraviolet and visible light irradiation. SEM and TEM observations suggest that preparation of FNWs and FNTs by irradiation using different wavelengths of light does not produce apparent morphological transformations on the surface of these fullerene materials.
SYNTHESIS OF FULLERENE NANOTUBES AND MICROTUBES FOR MATERIALS STORAGE, DELIVERY AND RECOVERY
Authors: MIYAZAWA K. , CHA S. , RINGOR C. , OKUDA J. , TANIGUCHI A. , WATANABE M. , TACHIBANA M. , MINATO J.
Published: February 2009

Tubular, needle-like crystals of C 60 with diameters ranging from micro to nano sizes have been synthesized by the liquid–liquid interfacial precipitation (LLIP) method. The C 60 nano- and microtubes can absorb various solutions of alcohol and water, showing that they can be promising containers for materials storage and recovery. Further, C 60 microtubes vertically aligned on porous alumina membranes have been successfully prepared for the first time by a modified LLIP method. The vertically aligned C 60 microtubes will find a variety of application for bio and environmental uses.
ORGANIC-METAL-DOPED FULLERENE NANOWHISKERS
Authors: WAKAHARA TAKATSUGU , SATHISH MARAPPAAN , MIYAZAWA KUN'ICHI , SASAKI TOSHIO
Published: February 2009

Two types of ferrocene( Fc )-doped C 60 nanowhiskers [ C 60/ Fc NWs and C 60/ferrocene pyrrolidine- C 60( C 60- Fc ) NWs] were prepared by the liquid–liquid interfacial precipitation method using toluene solution of C 60 and Fc or C 60- Fc and isopropyl alcohol (IPA). The morphology of C 60 precipitates was remarkably changed by the addition of Fc or C 60- Fc to the C 60 toluene solution. The scanning TEM mapping analysis of C 60/ Fc NWs showed that the intensity of ferrocene is high at the edge, indicating that ferrocene covers the outside surface of the NWs. In the case of C 60/ C 60- Fc NWs, however, the scanning TEM mapping analysis showed that C 60- Fc disperses well in the NWs.
SYNTHESIS AND CHARACTERIZATION OF A HIGHLY CRYSTALLINE NOVEL MESOPOROUS C- AND N-CODOPED TiO2 NANOPHOTOCATALYST
Authors: ANANDAN SRINIVASAN , IKUMA YASURO , KAKINUMA KATSUYOSHI , NIWA KOICHI
Published: February 2009

Here we report, for the first time, the synthesis of highly crystalline novel mesoporous carbon/nitrogen ( C / N )-codoped TiO 2 (MCNT) using ethylene diamine and carbon tetrachloride as the source for nitrogen and carbon, KIT-6 as the template, and titanium tetraisopropoxide as the TiO 2 source. The obtained material has been unambiguously characterized by various sophisticated techniques. XRD and TEM analysis revealed that the MCNT material possesses highly crystalline 3D structure with a continuous network of mesoporous channels as well as structure corresponding to TiO 2. UV-DRS analysis indicated that light absorption shifted to lower energy and stronger absorption in the visible light region. XPS revealed that C and N were doped effectively and C or N dopants might be present in the chemical environment of Ti – O – N or Ti – O – C . It has been found that the material is highly crystalline and possesses high surface area, pore volume and uniform pore size distribution. Owing to its textural characteristics, it could be useful for various applications, such as photocatalysis, fuel cells, bulky biomolecule adsorption and nanotechnology.
INTERACTION BETWEEN POSITIVE HYDROGEN IONS AND ELECTRONS LOCATED IN INDIUM NITRIDE CONTAINING OXYGEN IMPURITIES
Authors: ALEXANDROV DIMITER , YU GLORIA HANG
Published: February 2009

Theoretical investigation of the interaction between positive hydrogen ions and electrons located in wurtzite InN containing oxygen impurity atoms is presented in this paper. The interaction is investigated on the basis of the energy pockets for both the electrons and the holes having places in the structure of InN containing oxygen atoms. These energy pockets are found on the basis of the electron band structure of wurtzite InN containing oxygen impurity atoms. A model of the system located electron–positive hydrogen ion is created. It is called the "inversed" hydrogen model, because the electron is fixed in the pocket, and the positive hydrogen ion can change its position (this ion can either be on the surface of InN or belong to a neighboring quasi-elementary cell). The Schrödinger equation for the "inversed" hydrogen model of the electron–hydrogen ion system is determined. The binding energy and the hydrogen-like energy levels of the electron–positive system hydrogen ion system are found.
VISIBLE LIGHT PHOTOCATALYSIS BY TAILORING CRYSTAL DEFECTS IN ZINC OXIDE NANOSTRUCTURES
Authors: BARUAH SUNANDAN , RAFIQUE RAHMAN FAIZUR , DUTTA JOYDEEP
Published: February 2009

The photocatalytic activity of zinc oxide ( ZnO ) nanoparticles, films and nanowires as a potential visible light photocatalyst is presented in this work. ZnO nanoparticles were synthesized in different alcoholic solvents. Crystal defects were introduced either by doping the crystallites with manganese or by fast crystallization (using microwave irradiation during synthesis). ZnO , with a band gap of 3.37 eV, normally absorbs electromagnetic waves in the ultraviolet region, but introducing defects into its crystal lattice can shift the absorption more toward the visible light band from 400 nm to 700 nm by creating intermediate states which inhibit electron–hole recombination. The undoped ZnO nanoparticles synthesized using microwaves showed comparable photocatalytic activities to the doped samples using the conventional heating method. To increase the effective surface area of the photocatalyst, ZnO nanowires were grown by a solution-based technique. Methylene blue degradation was observed to be enhanced in the presence of the ZnO nanowires compared to the ZnO nanoparticles. Intentional defect creation in photocatalysts could be an attractive possibility to apply in the visible light photocatalytic degradation studies.
NANOSENSORS FOR MONITORING HAZARDOUS ENVIRONMENTS
Authors: MEDELIUS PEDRO J.
Published: February 2009

Personnel working in a confined environment can be exposed to hazardous gases. Certain gases can be extremely dangerous even in concentrations as low as a few parts per billion. The use of small and sensitive nanosensors can allow the placement of multiple devices over a large area, thus allowing for a precise and timely determination of a gas leak. ASRC Aerospace and its research partners are developing nanosensors for the detection of various gases, including but not limited to: H 2, NH 3, N 2 O 4, hydrazine, and others. Initial laboratory testing has demonstrated the capability to detect the gases in concentrations as low as a few parts per billion and laboratory evaluation is ongoing to determine the sensitivity at levels in the order of parts per trillion. Different coatings and electrodes are currently being evaluated to determine the optimum configuration for the detection and identification of a variety of gases.
ACP1 Genetic Polymorphism and Coronary Artery Disease: An Association Study
Authors: Banci M. , Saccucci P. , D’Annibale F. , Dofcaci A. , Trionfera G. , Magrini A. , Bottini N. , Bottini E. , Gloria-Bottini F.
Published: February 2009

Objectives: Assuming an immune component in the pathogenesis of atherosclerosis, we have investigated a possible association between coronary artery disease (CAD) and the acid phosphatase locus 1 (ACP1) genetic polymorphism, which has previously been found to be associated with immune disorders. Methods: 226 subjects admitted to the hospital for CAD, 358 consecutive newborn infants, 279 adult subjects with type 2 diabetes without CAD and 137 adults without diabetes and without CAD from the Caucasian population of Rome were studied. The ACP1 genotype was determined by DNA analysis. Statistical analyses were performed using the SPSS package. Results: CAD females showed an excess of ACP1 *A/*C and *B/*C genotypes and a deficiency of ACP1 *B/*B genotype compared to controls, while CAD males did not show significant differences. Among diabetic women the proportion of *C allele carriers was much greater in those with CAD than in those without CAD. This difference was much less evident in nondiabetic women. Conclusion: ACP1 may be involved in susceptibility to CAD. Since ACP1 has been found to be associated with immunological diseases, our observation reinforces the notion of an immune component in the pathogenesis of atherosclerosis.