bluuebunny/crossref_metadata_2025 huggingface dataset:
Differences in the gonadal cycles of adult and yearling blue grouse
Authors: Hannon S. J. , Simard B. R. , Zwickel F. C. , Bendell J. F.
Published: August 2008

Gonadal cycles of adult and yearling female and male blue grouse (Dendragapus obscurus fuliginosus) collected from Vancouver Island, British Columbia, are described and compared. Reproductive organs of yearling females develop later, produce eggs at a lower oviduct weight, and regress faster to a lower oviduct weight than do those of adults. Yearling males, although most do not breed, go through the entire gonadal cycle and produce viable sperm. Testes of yearlings develop later, have a lower volume, and regress earlier than those of adults. Yearlings of both sexes appear less sexually mature than adults, but delays in or lack of breeding could be partly a result of social interaction with resident adults.
Influence of vessel noises on underwater vocal activity of harp seals
Authors: Terhune J. M. , Stewart R. E. A. , Ronald K.
Published: August 2008

Recordings of harp seal (Pagophilus groenlandicus) underwater vocalizations were obtained on whelping patches in the Gulf of St. Lawrence, Canada. The seals vocalized throughout the day and night. A marked decrease in seal vocalizations occurred following the arrival of a vessel. The relatively loud motor noises of the vessel completely masked the seal calls (within a 2-km or more radius) except during the night when the vessel's motors were shut down. The decreased seal vocalizations may reflect a change in the seal's behaviour and (or) movement of some seals away from the area of the vessel.
Macroinfauna of Northern New England marine sand. IV. Infaunal ecology of Amphiporeia virginiana Shoemaker, 1933 (Crustacea: Amphipoda)
Authors: Hager Richard P. , Croker Robert A.
Published: August 2008

Amphiporeia virginiana occurs from Nova Scotia to South Carolina where it is a dominant inhabitant of high energy sand beaches. Maximum abundance occurs on the lower foreshore in fine sand particularly during summer months. Within-habitat segregation of sexes occurs, with females more abundant at higher beach levels; ovigerous females are confined to higher levels only. Annual population fluctuations of up to 14-fold on a geometric basis are related to life history events and sedimentary changes. Breeding occurs during most of the year with peak recruitment during June and late summer to early fall, yielding summer and overwintering generations. Precopulating animals are commonly seen swimming, with two males per female occasionally evident. Females produce a mean of 6–11 eggs during the year and have one brood per breeding period. The species is a detritivore and generally inhabits the upper 2.5 cm of sand. It is most tolerant of salinities in the range of 25–35‰; mortality increases rapidly in salinities less than 20‰, and in sediments containing less than 11% water by weight exposed to temperatures simulating hot summer days.
Contribution of organic shell matter to biomass estimates of unionid bivalves
Authors: Cameron C. J. , Cameron I. F. , Paterson C. G.
Published: August 2008

The amount of acid extractable organic matter in the shell is significantly different in Anodonta cataracta (3.75 ± 0.25% w/w), Elliptio complanata (2.79 ± 0.04%) and Lampsilis ochracea (2.26 ± 0.15%). Within a species values do not change with size or sex. The percentage ash and caloric content do not differ among the species and pooled data give values of 5.13 ± 0.27% and 4567.2 ± 283.5 cal/g dry weight respectively. The organic content of the shell accounted for between 4.6 and about 30% of the total energy content, depending on species and size.
Specific status of Keratella cochlearis (Gosse) and K. earlinae Ahlstrom (Rotifera: Brachionidae): morphological and ecological considerations
Authors: Baker Robert L.
Published: August 2008

Keratella cochlearis and K. earlinae were found to coexist in a shallow eutrophic lake in western Canada. Differences between the two populations were found with respect to size, shape, seasonal abundance, birth rate, and vertical distribution. Results suggest that the two populations represent stable species and not ecophenotypes as suggested by recent literature.
Notes on the recovery of live ostracods from the gut of the white sucker (Catostomus commersoni Lacépède) 1808, (Pisces: Catostomidae)
Authors: Victor Reginald , Chan G. L. , Fernando C. H.
Published: August 2008

Ten species of freshwater ostracods were ingested by Catostomus commersoni. Of these Physocypria pustulosa females were recovered alive from the gut and were able to reproduce. The possible significance of this observation to P. pustulosa dispersal is discussed.
The biology of Unionicola formosa (Dana and Whelpley): a water mite parasitic in the unionid bivalve, Anodonta cataracta (Say), in a New Brunswick lake
Authors: Gordon M. J. , Swan B. K. , Paterson C. G.
Published: August 2008

The eggs, teleiochrysalis, and adults of the water mite Unionicola formosa (Dana and Whelpley) occur in Anodonta cataracta whereas only the egg stage is found in the other three unionid bivalves in Morice Lake, New Brunswick. There is no selectivity for host sex. Female mites do not reside in smaller bivalves. The incidence of infection and host loading increases with bivalve length. No evidence was found for territoriality of females within the host or for seasonal variations in abundance of either males or females. Only one male mite resides in each infected host. Incidence of infection increases with host size up to 5 cm and then remains stable at about 52%. A positive male–female association occurs during the warm water period but not after the water cools. The sex ratio is 1.60 females: 1 male. The teleiochrysalis occurs in the siphons during July at a density approximately 2.5 times that of the adults. Eggs are laid from late May until early July in the mantle tissue of most available hosts. The eggs hatch the following June and the larvae leave. Nymphs are found periodically except when teleiochrysalises are present. The available data suggest a 3-year life cycle for U. formosa.
A description of the stages in the metamorphosis of the anadromous sea lamprey, Petromyzon marinus L.
Authors: Youson J. H. , Potter I. C.
Published: August 2008

A large number of larval, metamorphosing, and young feeding adults of the anadromous sea lamprey, Petromyzon marinus L., have been used to provide a detailed description of the external alterations that take place in this species as it changes from a larva to an adult. A total of seven metamorphosing stages (1–7) are described, using as a basis a variety of different morphological characters, such as the appearance of the eye (1–3), the structure of the oral aperture (2–4), the degree of development of the tongue-like piston (4–7), the shape and degree of cornification of the teeth (4–7), and the coloration of the body (5–7). Attention is drawn to the fact that, although the changes in individual characters may vary in their time of initiation and the duration of their development, the overall metamorphic process is relatively synchronous. In contrast to this synchrony, however, the time at which the downstream migration occurs is very variable, a feature which is probably of selective advantage to this species.
Three species of Digenea from the Atlantic leatherback turtle (Dermochelys coriacea)
Authors: Threlfall William
Published: August 2008

Three species of digenetic trematodes (Pyelosomum renicapite, Calycodes anthos, Cymatocarpus sp. (?)), are reported from two Atlantic leatherback turtles (Dermochelys coriacea) taken off the coast of Newfoundland and Labrador, in 1973. The status of the genera Pyelosomum Looss, 1899 and Astrorchis Poche, 1925 is discussed.
Larval development in the American lobster: changes in metabolic activity and the O:N ratio
Authors: Capuzzo Judith M. , Lancaster Bruce A.
Published: August 2008

The rates of oxygen consumption under conditions of feeding and starvation and the rates of ammonia excretion after feeding increased with each larval stage of the American lobster (Homarus americanus Milne Edwards) and decreased with the first postlarval stage. There was no significant difference in the O:N ratio of the first three larval stages (~26.5), but a significant reduction (P < 0.01) was measured among stages IV and V. It appears that, whereas protein catabolism may be the principal source of energy, some of the energy yield during larval development is from lipid or carbohydrate catabolism; the use of the latter substrates is diminished in the last larval and first postlarval stages.
Causes of the unequal sex ratio in populations of adult Richardson's ground squirrels
Authors: Schmutz S. M. , Boag D. A. , Schmutz J. K.
Published: August 2008

Four hypotheses, postulated to explain the unequal sex ratio characteristic of populations of adult Richardson's ground squirrels (Spermophilus richardsonii), were examined in a population of this species near Hanna, Alberta.One hypothesis, postulating a disproportionate loss of adult males in early spring, was supported by our observations. Males emerged earlier and were lost from study plots in greater numbers than females; they moved more widely, which probably increased their vulnerability to predation. A second hypothesis, postulating a disproportionate loss of juvenile males during their first summer, was also supported by our data. Loss of males exceeded that of females. Juvenile males moved farther and in greater numbers than females, which seemed to make them more vulnerable to predation; significantly more juvenile males than females were among the prey of buteos feeding young. That mortality through predation falls disproportionately on males, a third hypothesis, was therefore also supported. However, our data on loss from midsummer to the following spring do not support the hypothesis that differential mortality occurs over winter.
The prevalence of Sarcocystis Lankester, 1882, in some bird species in western Canada, with notes on its life cycle
Authors: Drouin T. E. , Mahrt J. L.
Published: August 2008

The prevalence of Sarcocystis in 930 birds of 58 species from western Canada is reported. All birds were examined for macroscopic cysts, and tissue from 916 birds was also examined histologically for microscopic cysts. Different prevalences were obtained for several species, and nine new host records are reported. Histological examination of muscle revealed Sarcocystis in many birds which would have otherwise been reported uninfected because only microscopic cysts were present. The prevalence of Sarcocystis in some anatids in Alberta was significantly different from two other surveys. Different migratory routes and overwintering g rounds in each of the studies are suggested as explanations for these findings. Several unsuccessful attempts to complete the life cycle using dogs, coyotes, mink, ferrets, cats, kittens, and rats are reported. The failure to establish infection in any of these carnivores with the macroscopic cysts from ducks is considered supporting evidence for the hypothesis that this parasite is transmitted by another host in another area.
Actomyosin ATPase activities in the brachiopod Terebratalia transversa
Authors: Eshleman William P. , Wilkens Jerrel L.
Published: August 2008

Actomyosin specific adenosine triphosphate (AM-ATPase) activities of muscles of the articulate brachiopod Terebratalia transversa were determined in an attempt to understand some of their unusual physiological properties. The striated adductors, smooth adductors, and ventral adjustors have activities of 0.318, 0.089, and 0.050 μmol of inorganic phosphate per minute per milligram of protein respectively, which correlate with their contraction rates and behaviors. The suggestion that sudden compliance to stretch in the diductor muscles (slip) is due to simultaneous breakage of all cross bridges is supported by the low activity of 0.022 μmol of inorganic phosphate per minute per milligram of protein. This rate of activity is not as low as expected from the extremely slow rate of isometric contraction (186 min) but it does correlate with the faster rate of isotonic contraction observed after removal of the antagonistic smooth adductors. Slippage represents a previously unknown extreme in the macromolecular organization and kinetics of a contractile system, an elegant adaptation of articulate brachiopods to minimize the metabolic cost of keeping the valves open while allowing rapid closure in an emergency.
Distribution of the American dog tick, Dermacentor variabilis (Say), and its small-mammal hosts in relation to vegetation types in a study area in Nova Scotia
Authors: Campbell A. , MacKay P. R.
Published: August 2008

The distribution of Dermacentor variabilis and its mammal hosts was related to vegetation types found in a 12-ha area of southwestern Nova Scotia during summers of 1974 to 1977. Cluster and principal component analyses were used to elucidate these relationships. Habitats, live-trapped for small mammals, were categorized into seven major vegetation types: old field, ecotone – old field, ecotone–powerline, shrubs–trees, mixed woods low–wet, mixed woods open canopy, and mixed woods closed canopy. Clethrionomys gapperi, Peromyscus spp. (mainly P. leucopus, about 10% P. maniculatus) and Tamias striatus were most frequently trapped in the mixed deciduous and coniferous wood areas, although the latter two genera were also captured in the old field and ecotone – old field areas. Microtus pennsylvanicus, Zapus hudsonius, and adult and nymph stages of Dermacentor variabilis occurred most frequently in the old field and ecotone areas. Tick nymphs fed almost exclusively on Microtus pennsylvanicus, but also utilized Peromyscus spp. in the ecotone and woodland areas. In contrast to the nymphs, over half the tick larvae were collected from Clethrionomys gapperi and Peromyscus spp. captured in the ecotone–powerline, shrubs–trees, and mixed wood areas, whereas less than half the tick larvae were collected from mammals inhabiting the old field and ecotone – old field areas. Peromyscus spp. probably helped disperse engorged tick larvae from the woodland to the old field and ecotone areas.
Integumentary toxicity and unpalatability as an antipredator mechanism in the narrow mouthed toad, Gastrophryne carolinensis
Authors: Garton Jilda Diehl , Mushinsky Henry R.
Published: August 2008

Gastrophryne carolinensis was eaten by four potential vertebrate predators, significantly less frequently than control anurans. The combined responses of all predators was to reject G. carolinensis in 60% of the experimental trials (χ2 = 20.49; p < 0.01), whereas controls were rejected in less than 5% of trials (7/150). The most frequent response of all predators was to contact, bite, and then release the unharmed frog. Prolonged periods of distress by the predators following contact with the toad and the additional time needed for ingestion make it energetically disadvantageous to eat G. carolinensis when alternatives are available. Injections of 3 mg G. carolinensis skin per gram body weight killed mice within 15 min. Rana catesbeiana skin caused no observable distress behaviors.Granular and mucous glands are found in the stratum spongiosum of all regions of the skin of G. carolinensis and G. olivacea adults. Scanning electron micrographs of secretory gland pores reveal a uniform distribution of the glands throughout the body covering. In tadpoles the pores and underlying glands appear in the dermis of the skin at the time of forelimb emergence, which coincides with the onset of toxicity. Skin secretions also function in the feeding ecology of Gastrophryne spp. by protecting the frogs from counterattacks from ants, their primary prey.
Factors influencing heart rate in free-ranging bighorn sheep: a physiological approach to the study of wildlife harassment
Authors: MacArthur Robert A. , Johnston Ronald H. , Geist Valerius
Published: August 2008

The telemetered heart rates (HR) of unrestrained female bighorn sheep (Ovis canadensis canadensis) were recorded under various behavioral and environmental circumstances. In all ewes HR varied positively with activity level and inversely with distance to a road traversing the study area. The HR recorded from animals moving at night or through timber by day were higher than during daytime movement across open slopes.Responses to transient stimuli varied greatly. The appearance of free-ranging canids evoked maximal increases in HR in all ewes. Vehicular traffic and aircraft elicited HR responses only at close range (< 200 m). Most (78.1%) HR responses to disturbing stimuli preceded or occurred in the absence of overt behavioral reactions. The HR usually peaked within 60 s of the onset of the response and recovered to predisturbance base line in less than 200 s. The appearance and continued presence (1–10 min) of a human within 50 m of the sheep resulted in a 20% rise in mean HR. The significance of these findings is discussed in relation to the behavior, ecology, and bioenergetics of bighorn sheep.
Analysis of the food niche of Glossiphonia complanata (Hirudinoidea: Glossiphoniidae)
Authors: Wrona Frederick J. , Davies Ronald W. , Linton L.
Published: August 2008

The food niche of Glossiphonia complanata was evaluated in the field using a serological technique. The feeding ecology of the species was similar in the two field sites examined, both populations displaying similar trends in prey utilization on a temporal and weight (size–age) basis. Field "prey range" of G. complanata was determined to consist of Gastropoda, which formed the highest proportion of the diet, followed in decreasing magnitude by Oligochaeta, Chironomidae, and Amphipoda, respectively. Feeding activity was lowest in winter and early spring and highest in late spring and summer. The temporal trend in prey utilization (winter to summer) was a continual decrease in Chironomidae and Amphipoda consumption, with a corresponding increase in the proportion of Gastropoda and Oligochaeta utilized. Glossiphonia complanata was found to partition food resources on the basis of weight (size–age) differences. Separation in food niche utilization by the weight classes was determined to be a function of a decrease in the proportion of Oligochaeta utilized and an increase in the amount of Chironomidae and Amphipoda consumed with increased predator size. Possible explanations for the observed temporal and weight (size–age) differences in prey utilization are forwarded.
Branchial circulation and gill morphometrics in the sturgeon Acipenser transmontanus, an ancient Chondrosteian fish
Authors: Burggren Warren , Dunn Jeff , Barnard Kelly
Published: August 2008

Gill morphometries and branchical circulation have been examined in sturgeon, Acipenser transmontanus, weighing from 1 to 336 kg.Weight-specific gill area of the lamellar blood channels, approximately 0.9 cm2/kg in 2–8 kg Acipenser, is low compared with that of other fishes, and probably reflects a low activity level and metabolic rate in the sturgeon. Gill arches III–VI contribute 98% of the respiratory surface area of the sturgeon. However, Acipenser retains gill tissue representing all six embryonic arches. The spiracular pseudobranch (arch I) is perfused with oxygenated blood, while the well developed opercular gill (arch II) receives deoxygenated blood from the ventral aorta. Although comprising only 2% of total gill surface area, anatomical evidence indicates that gill arch II functions in gas exchange and is the major source of blood for certain ventilatory muscles of the operculum.Lamellae on all branchial filaments of all arches can be placed into one of five surface area classes, each class bearing a quantitative area relationship to all others. Since surface areas of the various gill arches also bear certain quantitative and consistent interrelationships, total gill surface area could be accurately predicted for sturgeon on the basis of data from single hemibranchs.
Circulation in trout gills: the relationship between branchial perfusion and the width of the lamellar blood space
Authors: Booth John H.
Published: August 2008

Experiments were carried out to examine the role of pillar cell contraction in changes in branchial flow rate in isolated-perfused gill arches and in the distribution of blood flow in the gills in vivo. Although administration of adrenaline caused a 43% increase and acetylcholine caused a 59% decrease in the efferent branchial flow rate through isolated gill arches, the average width of the lamellar blood space was actually larger in the gills of the acetylcholine-treated group. In the in vivo experiments, only about 60% of the secondary lamellae were actively perfused at a given instant. The average width of the lamellar blood space was the same whether or not the lamellae were being perfused. It was concluded that pillar cell contraction was not involved in the observed differences in branchial circulation between the experimental groups in vitro or in vivo.
Biology and population characteristics of the shortnose sturgeon, Acipenser brevirostrum LeSueur 1818 (Osteichthyes:Acipenseridae), in the Saint John River Estuary, New Brunswick, Canada
Authors: Dadswell M. J.
Published: August 2008

During a 4-year study, 4178 shortnose sturgeon were captured and 2453 marked with numbered tags and released. For adults, Z was estimated as 0.12–0.15 and F was estimated as 0.01. The population weight–length relationship was log W = 3.21 (log FL) − 5.45, where W = weight in kilograms and FL = fork length in cm. The oldest female was 67 years; the oldest male was 32 years. Von Bertalanffy growth parameters L∞, W∞, and K were 127.0 cm, 24.8 kg, and 0.047 for females, and 108.7 cm, 13.9 kg, and 0.063 for males. Sex ratio of adults was 2:1 for females. Males spawned first about age 12 and probably at 2-year intervals thereafter; females spawned at 18 years and 3- to 5-year intervals thereafter. Fecundity was 27 000 – 208 000 eggs per female. Spawning occurs in freshwater, riverine sections of the upper estuary during May–June at 10–15 °C. Feeding occurred only during May to October in fresh water but continued all year in saline water. Juveniles ate mainly insects and crustaceans; adults ate small molluscs. Juveniles remained in fresh water until they attained 45 cm, then joined the regular annual migration of adults, which moved upstream in spring–summer and seaward in fall. Many ripening females migrated upstream in fall and overwintered in deep, freshwater sites adjacent to spawning grounds. The Seber-Jolly estimate of the adult (> 50 cm) population was 18 000 ± 30%.
Ontogenetic migration and the distribution of Eucalanus bungii (Copepoda; Calanoida) in British Columbia inlets
Authors: Krause Edith Penner , Lewis A. G.
Published: August 2008

The distribution of Eucalanus bungii Giesbrecht (1892) in selected British Columbia inlets is examined. At least part of the population undergoes a vertical migration during the life cycle. The geographic distribution is suggested to be controlled by topographic features of the inlets and by the time of the vertical migration with respect to water movement into the inlets.
Migration and sexual selection in Ambystoma jeffersonianum
Authors: Douglas Michael Edward
Published: August 2008

Initiation of reproductive migration, structure of the breeding population, and length of the breeding season in Ambystoma jeffersonianum were studied for two consecutive winters at a small, sylvan pond in Kentucky. Early response to cues of temperature and precipitation, and continued movement under declining nocturnal temperatures enabled males to arrive at the pond sooner and in greater numbers than females, who frequently moved later and under prolonged periods of favorable conditions. During 1973, movement conditions were favorable, and males arrived in greater numbers and stayed significantly longer at the pond than in 1974 when male movement periods were reduced, males were fewer in number, and their length of stay was shorter. The number of females and their mean duration of stay were virtually identical in each season. Breeding congregations that become increasingly skewed toward males are known to precipitate intense male–male competition and male sexual interference. Hence the intensity of sexual selection was believed to have been greater in 1973 than in 1974.Although the mating system of A. jeffersonianum adapts quickly to changes in the environmental potential for polygamy, ecological constraints of temperature and precipitation apparently limit the degree to which sexual selection can operate within local populations of this species.
Effects of host anemia, local skin factors, and circulating antibodies upon biology of laboratory reared Glossina morsitans morsitans Westwood (Diptera: Glossinidae)
Authors: Parker K. R. , Gooding R. H.
Published: August 2008

Longevity, productivity, and pupal weights, but not emergence from pupae, were lower in Glossina morsitans morsitans females maintained on previously exposed rabbits than in those maintained on naive rabbits. Male and female longevity and pupal weight, but not female productivity or emergence from pupae, were lower in flies maintained on the previously exposed ear than in those maintained on the naive ear of the same rabbit. Intensity of local resistance varied among rabbits. Flies fed more efficiently (i.e. larger meals and fewer probes) from ears than from backs of rabbits. Longevity, productivity, and pupal weight were not influenced by feeding flies on ears, on backs, or on both. Mortality was greater in lighter flies than in heavier ones during the first 20 days after eclosion if the flies were fed on rabbits' backs. Naturally produced circulating antibodies, which react with tsetse salivary gland homogenates, did not affect tsetse longevity, female productivity, or pupal weight. Flies maintained on anemic rabbits produced lighter pupae than did controls. Implications for colony maintenance and possible mechanisms of acquired host resistance are discussed.
Parasite-induced susceptibility of moose to hunting
Authors: Rau Manfred E. , Caron Francois R.
Published: August 2008

Moose heavily infected with Echinococcus granulosus cysts are more susceptible to being killed by hunters than are uninfected or lightly infected animals. The data suggest that a reduction in moose hydatid disease may be amenable to management strategies involving selective hunting.
The origins of zooparasitic nematodes
Authors: Anderson R. C.
Published: August 2008

Zooparasitic nematodes are derived from soil nematodes and parasitism apparently originated only after land animals appeared. A major line from soil dwelling rhabditids gave rise to the secernentean parasites, which constitute about 98% of all genera in vertebrates and about 80% of those in invertebrates. A minor line evolved from the predominantly soil-dwelling dorylaimids and gave rise to adenophorean parasites, including mermithoids, trichinelloids, and dioctophymatoids. Nematodes are common in terrestrial invertebrates but rare in aquatic invertebrates (e.g., polychaetes, molluscs, crustaceans). The fauna in terrestrial vertebrates is rich and diversified. In contrast, the fish nematode fauna is limited. Only 17 families of nematodes occur in fishes and only 5 are unique to the fishes. No unique nematode superfamilies occur in fishes. The fish nematode fauna seems closely related to that in terrestrial vertebrates and is evidently derived from it since almost three quarters of the families are shared with those in terrestrial vertebrates. Transfer to fishes from terrestrial hosts during the course of evolution probably occurred mainly through heteroxeny and paratenesis; however, a few monoxenous forms (oxyuroids) from terrestrial arthropods became established in shallow water fishes. Only a few nematodes (i.e., mermithoids) transferred from terrestrial to aquatic invertebrates with the result that nematodes are extremely rare in freshwater and marine invertebrates. The nematode fauna of marine mammals is limited mainly to heteroxenous forms with affinities to nematodes of terrestrial mammals.
Effects of parasite strain and intermediate host species on carbohydrate intermediary metabolism in the rat tapeworm, Hymenolepis diminuta
Authors: Mettrick D. F. , Rahman M. S.
Published: August 2008

Two strains of Hymenolepis diminuta were reared using Tribolium confusum and Tenebrio molitor as intermediate hosts. The carbohydrate metabolism, excreted end products, and adenine nucleotide levels of the adult parasites were compared following 60-min in vitro incubations, in the presence or absence of 5-hydroxytryptamine (5-HT). The strain of parasite, species of intermediate host, and the presence of 5-HT had significant effects on tissue levels of intermediaries in carbohydrate metabolism. Metabolic activity was greater when Tr. confusum was the intermediate host. With Te. molitor, the pool sizes and excretory products were increased compared with Tr. confusum. Discriminant analysis indicated that fructose-1,6-diphosphate (FDP) and phosphoenolpyruvate accounted for 82% of the significant variance between the two parasite strains; succinate accounted for 39% of the differences between hosts; lactate, FDP, pyruvate, and acetate accounted for 45% of the differences owing to 5-HT. Acetate and lactate excretion accounted for 47% of the variance between strains; lactate, acetate, and total end products accounted for 58% of the variance between hosts; lactate, acetate, and total excreted products accounted for 38% of the variance owing to 5-HT. AMP accounted for 20% of the variance between strains; ATP and ADP accounted for 74% of the variance between hosts.
Exploitation and interference intraspecific larval competition in the dipteran leaf miner, Agromyza frontella (Rondani)
Authors: Quiring Daniel T. , McNeil Jeremy N.
Published: August 2008

The effect of competition among similarly aged larvae of the alfalfa blotch leaf miner, Agromyza frontella (Rondani), was investigated in laboratory studies over a range of larval densities (1–10 larvae per leaflet) commonly found on alfalfa in Quebec. In these studies A. frontella larvae were found to be resource limited when developing in small leaflets and (or) with other larvae. Larval mortality owing to interference (cannibalism) during the first two larval instars, and exploitation (starvation) competition during the third and final instar, increased in a density-dependent manner. Prepupal and pupal mortality increased and pupal weight decreased as larval density increased. However, pupal developmental rates and adult sex ratios of survivors were not significantly affected by larval density. Interference competition during the first two larval instars reduced larval density and thus diminished the probability that third-instar larvae would be subjected to exploitation competition. These findings were confirmed under field conditions.
The diet of the eastern short-horned lizard (Phrynosoma douglassi brevirostre) in Alberta and its relationship to sexual size dimorphism
Authors: Powell G. Lawrence , Russell Anthony P.
Published: August 2008

The diet of Phrynosoma douglassi brevirostre in Alberta was investigated and potential prey abundance was examined. The Alberta populations are less strongly myrmecophagous than the average for the species, when the diet is broken down by prey item counts. Breakdown of the diet by prey dry weight shows that ants, nonsilphid Coleoptera, and Orthoptera are the major components of the diet. The range of prey sizes taken is large, but the species concentrates on a small range of prey sizes, from 2.1 to 6.0 mm in length. Arthropod abundances are significantly different between all three study sites, and there is always a significant difference in distribution between the pooled pitfall samples and the pooled gut samples of any one study site. The general dissimilarity in distribution between the pooled gut samples of any two study sites suggests some dietary flexibility. The size range of prey items taken by the large lizards includes and slightly exceeds the size range of prey items taken by medium-sized lizards, and there is a significant positive correlation of average prey size with lizard snout–vent length. There are significant differences in the prey sizes, prey dry weights, and prey item counts between large lizards and medium-sized lizards, indicating intersexual dietary partitioning.
Genomic and nongenomic dose-dependent biphasic effect of aldosterone on Na+/H+exchanger in proximal S3 segment: role of cytosolic calcium
Authors: Leite-Dellova D. C. A. , Oliveira-Souza M. , Malnic G. , Mello-Aires M.
Published: August 2008

The effects of aldosterone on the intracellular pH recovery rate (pHirr) via Na+/H+exchanger and on the [Ca2+]iwere investigated in isolated rat S3 segment. Aldosterone [10−12, 10−10, or 10−8M with 1-h, 15- or 2-min preincubation (pi)] caused a dose-dependent increase in the pHirr, but aldosterone (10−6M with 1-h, 15- or 2-min pi) decreased it (these effects were prevented by HOE694 but not by S3226). After 1 min of aldosterone pi, there was a transient and dose-dependent increase of the [Ca2+]iand after 6-min pi there was a new increase of [Ca2+]ithat persisted after 1 h. Spironolactone, actinomycin D, or cycloheximide did not affect the effects of aldosterone (15- or 2-min pi) but inhibited the effects of aldosterone (1-h pi) on pHirr and on [Ca2+]i. RU 486 prevented the stimulatory effect of aldosterone (10−12M, 15- or 2-min pi) on both parameters and maintained the inhibitory effect of aldosterone (10−6M, 15- or 2-min pi) on the pHirr but reversed its stimulatory effect on the [Ca2+]ito an inhibitory effect. The data indicate a genomic (1 h, via MR) and a nongenomic action (15 or 2 min, probably via GR) on [Ca2+]iand on the basolateral NHE1 and are compatible with stimulation of the NHE1 by increases in [Ca2+]iin the lower range (at 10−12M aldosterone) and inhibition by increases at high levels (at 10−6M aldosterone) or decreases in [Ca2+]i(at 10−6M aldosterone plus RU 486).
Heme oxygenase metabolites inhibit tubuloglomerular feedback (TGF)
Authors: Ren YiLin , D'Ambrosio Martin A. , Wang Hong , Liu Ruisheng , Garvin Jeffrey L. , Carretero Oscar A.
Published: August 2008

Tubuloglomerular feedback (TGF) is the mechanism by which the macula densa (MD) senses increases in luminal NaCl concentration and sends a signal to constrict the afferent arteriole (Af-Art). The kidney expresses constitutively heme oxygenase-2 (HO-2) and low levels of HO-1. HOs release carbon monoxide (CO), biliverdin, and free iron. We hypothesized that renal HOs inhibit TGF via release of CO and biliverdin. Rabbit Af-Arts and attached MD were simultaneously microperfused in vitro. The TGF response was determined by measuring Af-Art diameter before and after increasing NaCl in the MD perfusate. When HO activity was inhibited by adding stannous mesoporphyrin (SnMP) to the MD perfusate, the TGF response increased from 2.1 ± 0.2 to 4.1 ± 0.4 μm ( P = 0.003, control vs. SnMP, n = 7). When a CO-releasing molecule, (CORM-3; 50 μM), was added to the MD perfusate, the TGF response decreased by 41%, from 3.6 ± 0.3 to 2.1 ± 0.2 μm ( P < 0.001, control vs. CORM-3, n = 12). When CORM-3 at 100 μM was added to the perfusate, it completely blocked the TGF response, from 4.2 ± 0.4 to −0.2 ± 0.3 μm ( P < 0.001, control vs. CORM-3, n = 6). When biliverdin was added to the perfusate, the TGF response decreased by 79%, from 3.4 ± 0.3 to 0.7 ± 0.4 μm ( P = 0.001, control vs. biliverdin, n = 6). The effects of SnMP and CORM-3 were not blocked by inhibition of nitric oxide synthase. We concluded that renal HO inhibits TGF probably via release of CO and biliverdin. HO regulation of TGF is a novel mechanism that could lead to a better understanding of the control of renal microcirculation and function.
hTERT alone immortalizes epithelial cells of renal proximal tubules without changing their functional characteristics
Authors: Wieser Matthias , Stadler Guido , Jennings Paul , Streubel Berthold , Pfaller Walter , Ambros Peter , Riedl Claus , Katinger Hermann , Grillari Johannes , Grillari-Voglauer Regina
Published: August 2008

Telomere-dependent replicative senescence is one of the mechanisms that limit the number of population doublings of normal human cells. By overexpression of telomerase, cells of various origins have been successfully immortalized without changing the phenotype. While a limited number of telomerase-immortalized cells of epithelial origin are available, none of renal origin has been reported so far. Here we have established simple and safe conditions that allow serial passaging of renal proximal tubule epithelial cells (RPTECs) until entry into telomere-dependent replicative senescence. As reported for other cells, senescence of RPTECs is characterized by arrest in G1phase, shortened telomeres, staining for senescence-associated β-galactosidase, and accumulation of γ-H2AX foci. Furthermore, ectopic expression of the catalytic subunit of telomerase (TERT) was sufficient to immortalize these cells. Characterization of immortalized RPTEC/TERT1 cells shows characteristic morphological and functional properties like formation of tight junctions and domes, expression of aminopeptidase N, cAMP induction by parathyroid hormone, sodium-dependent phosphate uptake, and the megalin/cubilin transport system. No genomic instability within up to 90 population doublings has been observed. Therefore, these cells are proposed as a valuable model system not only for cell biology but also for toxicology, drug screening, biogerontology, as well as tissue engineering approaches.
Task-Dependent Modulation of Propriospinal Inputs to Human Shoulder
Authors: Roberts Lynley V. , Stinear Cathy M. , Lewis Gwyn N. , Byblow Winston D.
Published: August 2008

In the human upper limb a proportion of the descending corticospinal command may be relayed through cervical propriospinal premotoneurons. This may serve to coordinate movements involving multiple joints of the arm, such as reaching. The present study was conducted to determine whether a shoulder stabilizing muscle, infraspinatus (INF), is functionally integrated into the putative cervical propriospinal network, and whether there is task-dependent modulation of the network. Fourteen healthy adults participated in this study. Responses in the right INF were evoked by transcranial magnetic stimulation over the motor cortex and compared with responses conditioned by ulnar nerve stimulation. Interstimulus intervals were chosen to summate inputs at the level of the premotoneurons. Participants performed a forearm and shoulder muscle cocontraction task or a grip-lift task that also coactivated forearm and shoulder muscles. During the cocontraction task, INF motor-evoked potentials were significantly facilitated by ulnar nerve stimulation at low intensities and suppressed at higher intensities. Only facilitation reached significance during the grip-lift task. We have shown for the first time that propriospinal pathways may connect the hand to the rotator cuff of the shoulder. The modulation of facilitation/suppression during the grip-lift task suggests that inhibition of propriospinal premotoneurons is down-regulated in a task-dependent manner to increase the gain in the feedback reflex loop from forearm and hand muscles as required.
Biocidal Silver and Silver/Titania Composite Films Grown by Chemical Vapour Deposition
Authors: Sheel D. W. , Brook L. A. , Ditta I. B. , Evans P. , Foster H. A. , Steele A. , Yates H. M.
Published: August 2008

This paper describes the growth and testing of highly active biocidal films based on photocatalytically active films of TiO2, grown by thermal CVD, functionally and structurally modified by deposition of nanostructured silver via a novel flame assisted combination CVD process. The resulting composite films are shown to be highly durable, highly photocatalytically active and are also shown to possess strong antibacterial behaviour. The deposition control, arising from the described approach, offers the potential to control the film nanostructure, which is proposed to be crucial in determining the photo and bioactivity of the combined film structure, and the transparency of the composite films. Furthermore, we show that the resultant films are active to a range of organisms, including Gram‐negative and Gram‐positive bacteria, and viruses. The very high‐biocidal activity is above that expected from the concentrations of silver present, and this is discussed in terms of nanostructure of the titania/silver surface. These properties are especially significant when combined with the well‐known durability of CVD deposited thin films, offering new opportunities for enhanced application in areas where biocidal surface functionality is sought.
Analysis and Design of Gap‐Coupled Annular Ring Microstrip Antenna
Authors: Kanaujia Binod Kumar , Singh Anil Kumar
Published: August 2008

Theoretical investigation conducted on gap‐coupled annular ring microstrip antenna is found to exhibit frequency tunability with the gap. The various parameters of the antenna such as input impedance, VSWR, return loss, and radiation pattern have been investigated as a function of gap length and feed point. It is found that the various parameters of gap‐coupled microstrip antenna depend heavily on the gap length and feed points.
Order in Garment Markets
Authors: Aspers Patrik
Published: August 2008

The purpose of this theoretical article is to analyse the social construction of order in two connected markets in the production flow of the global garment industry. The consumer market is identified as a status market, while the production market is defined as a `standard' market. In a `status' market, order is maintained because the identities of actors on both sides of the market are ranked according to status, which is a more entrenched social construction than the commodity traded in the market. In a market characterized by `standard', the situation is the reverse: the commodity is a more entrenched social construction than the identity rankings of actors in the market. The study ties together consumption and production of garments through several markets.
Electromagnetic Shielding Effectiveness of Multifunctional Metal Composite Fabrics
Authors: Roh Jung-Sim , Chi Yong-Seung , Tae Jin Kang  , Nam Sang-wook
Published: August 2008

The growth of the electronic industry and the widespread use of electronic equipment in communications, computations, automations, bio-medicine, space, and other purposes have led to many electromagnetic interference (EMI) problems as systems operate in close proximity. It is likely to become more severe in the future, unless proper EMI control methodology and techniques are used to meet the electromagnetic compatibility requirements. This article presents a comprehensive review of EMI shielding theory and materials. Furthermore, a method for fabricating a multifunctional metal composite fabric with electromagnetic (EM) shielding characteristics was successfully developed. The parameters influencing EM shielding properties of the metal composite fabrics were investigated. It was shown that the EM shielding effectiveness of the metal composite fabrics could be tailored by modifying the metal grid size and geometry.
Effect of Heating Rate on the Chemical Reaction during Stabilization of Polyacrylonitrile Fibers
Authors: Yongping Hou  , Tongqing Sun  , Haojing Wang  , Dong Wu
Published: August 2008

The influence of the heating rate on the stabilization process of polyacrylonitrile (PAN) fibers was studied. The results show that with an increase in heating rate, the density and oxygen content show a continuous decrease. As a result, the strength continues to increase and the skin-core structure becomes more evident. However, the amount of shrinkage and the conversion index ( A I) are lowest at 5°C/min. On the basis of these observations, we conclude that at a heating rate lower than 5°C/min the intramolecular cyclization is the main reaction and its extent decreases with an increase in heating rate. Above 5°C/min, an intermolecular cross-linking reaction becomes more obvious and increases with an increase in heating rate.
Study on Reduction of Air Consumption on Air-jet Weaving Machines
Authors: Göktepe Özer , Bozkan Orcun
Published: August 2008

As is well known, the main disadvantage of air-jet weaving machines is their high energy costs compared to projectile and rapier weaving machines. This makes air-jet looms less preferable for companies in countries such as Turkey that suffer from very high energy costs, despite their higher production speeds. Air-jet weaving loom manufacturers have continuously been working on the reduction of air consumption in their new designs to overcome this drawback. However, weaving mill practices are as important as machine designs on air consumption. In this study, therefore, we aim to investigate the possibilities to reduce air consumption on current air-jet weaving looms without making a new investment in a weaving mill. A decrease of air consumption by 21% was accomplished in a weaving mill by just decreasing the hole diameter of the single-holed relay nozzles and by optimizing the blowing time of the multi-holed relay nozzles. Thus, a company having 202 looms could save 240,000 per year in electricity costs with almost no expense. This paper explains the experimental work conducted in the weaving mill to minimize air consumption on air-jet looms.
Simulation models for gas transmission networks
Authors: Fincham A.E. , Goldwater M.H.
Published: August 2008

This paper reviews the methods which have been developed to solve the equations of gas flow in pipes. These methods have been incorporated into computer programs which are used to simulate the behaviour of gas transmission and distribution systems. The equations, representing conservation of mass and a force balance, are subjected to various treatments (namely the methods of finite differences, characteristics, and Galerkin) which must include provision for time-dependent non-linear boundary conditions and machine constraints. For most purposes the equations can be greatly simplified without loss of any important information.
Analysis of pump interaction and efficiency in control of water supply
Authors: Sterling M.J.H. , Coulbeck B.
Published: August 2008

The paper analyses water distribution system pumping elements in order to derive models suitable for incorpor ation in network simulation and optimisation schemes. This includes derivation of an independent control variable to give simulated pump operation on a continuous or discrete basis allowing for head dependent flows. Derivation of the necessary conditions for operation at maximum efficiency are also presented. Typical pumping operations are investigated in order to develop and justify cost models for various optimisation techniques in terms of electricity charges.
Test installations to investigate the dynamic behaviour of aircraft with scaled models in wind tunnels
Authors: Subke H.
Published: August 2008

It is possible to investigate the dynamic behaviour of future aircraft with scaled models which fly, suspended by a vertical rod, in. the airstream of a wind tunnel These models have to be similar with respect to mass and mass distribution, length, and time.

The transformation laws between model and aircraft are derived, and the test installation is described Finally, a comparison is given between the transient response of a model flying in a wind tunnel and the results of a flight simulation with an analogue computer.
Additional techniques in control system design
Authors: Hind E.C.
Published: August 2008

The concept of diagram scale change is used to develop a set of design curves which are independent of gain and may be used for any type 1 system and for most type 0 systems. A method is presented which enables both the system gain and compensator time constants to be evaluated when both the type of response and a characteristic response time are specified. A method is also shown for designing parallel compensators for closed loop systems.
Prediction of I imit cycle conditions in non-linear sampled data systems
Authors: Lewis C.P.
Published: August 2008

A novel technique for the determination of describing functions for non-linear sampled-data system elements is applied to the prediction of limit cycling conditions. A simple example is used to illustrate the method.