bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of condition and age on bone measurements and minerals in the mountain hare
Authors: Soveri Timo , Aarnio Martti , Tanhuanpää Eero
Published: September 2008

Sixty mountain hares (Lepus timidus L.) were shot during the fall and winter during 1980–1983 in Finland. Weight, length, and density of whole dried radius and ulna with bone marrow were measured, bones were ashed, and ash, calcium, phosphorus, and magnesium were determined. Adult hares had lower bone magnesium levels and their bones were heavier, longer, and denser than those of juveniles. Hares in poor condition had significantly higher bone ash content than hares in better condition. The determination of ash content from whole bones could be a suitable method to estimate the condition of carcasses from skeletons or decomposed remains of small mammals.
Behavioral ecology of killer whales (Orcinus orca) in the Pacific Northwest
Authors: Heimlich-Boran James R.
Published: September 2008

Killer whales (Orcinus orca) were found to use different physiographic regions of their habitat in unique ways. Resident whales fed more in areas of high relief subsurface topography along salmon migratory routes, and may use these geographic features to increase feeding efficiency. Transient whales fed in shallow protected areas around concentrations of their prey, harbor seals (Phoca vitulina). Whales traveled across deep, featureless areas in moving from one feeding area to another. Whales rested depending on the previous sequence of behaviors and played in open water areas or adjacent to feeding areas. The location of food resources and habitats suitable for prey capture appears to be the prime determining factor in the behavioral ecology of these whales. These patterns of behavior most likely represent cultural mechanisms that have been learned through trial and error experiences leading to successful foraging strategies.
Comparison of community structure among streams with different temporal flow regimes
Authors: Delucchi Carla M.
Published: September 2008

A study was conducted in four streams in the same watershed in New York to determine whether the benthic invertebrate community structure varied among streams with different temporal flow regimes. Timed kick samples were taken from 13 riffles and 4 pools once a month from June to November 1982. Riffle sites were classified according to temporal flow regime as permanent, intermittent (dry for less than 3 months), or dry (dry for over 3 months), and varied in size as a function of discharge. Ordination analysis (detrended correspondence analysis) showed that the structure of the benthic invertebrate communities in these streams was related not only to riffle permanence, but also to other abiotic and biotic parameters. Differences in community structure were greater between adjacent pools and riffles than between temporary and permanent riffles. Stream size, seasonal changes in taxa, how recently the riffle had dried, and the length of the dry period contributed to differences in community structure among riffles. It appears that differences in community structure between permanent and temporary riffles are minimized by generalized adaptations of stream benthos, such as high rates of migration, drought-resistant eggs, and the tendency to take refuge in the hyporheic zone.
Influence of snow depth on prey availability and habitat use by red fox
Authors: Halpin Margaret A. , Bissonette John A.
Published: September 2008

Habitat use by red fox (Vulpes vulpes) was studied during the winters of 1982 and 1983. A total of 125 km of fox trails in eastern Maine were followed during periods of snow cover to examine the influence of snow conditions on fox habitat selection and prey availability. Red foxes used all available habitats but showed preferences for softwood stands and open areas. Hardwood forests were avoided. During both winters, snow depth was greatest in hardwood and mixed stands where soft, powdery conditions prevailed. Windblown, supportive crusts were found in open barrens. Foxes showed habitat preferences for traveling and hunting. Fox sinking depths were least in all habitats when crust conditions prevailed, and during these periods travel distances were more evenly distributed among habitats. Snow influenced relative prey availability. Hunting activities shifted among habitats for small mammals during most of the second winter, when snow was shallow. Proportions of small mammals in the fox diet decreased as snow accumulated and as crusts formed. When snow was deep, foxes hunted in habitats with softwood regeneration and other dense understories that supported snowshoe hare concentrations.
Vigilance and diet selection: a simple example in the dark-eyed junco
Authors: Lima Steven L.
Published: September 2008

A straightforward prediction of "classical" optimal diet theory is that an animal should consume only the more profitable of two prey types (in terms of energy/time) in an environment where search time is negligible. However, such a simple diet is not necessarily expected if an animal feeds under the risk of predation. If an animal chooses to be vigilant for predators, and if the degree to which prey handling and vigilance are mutually exclusive varies positively with prey profitability, then the optimal diet may be a mixture of both prey types. The proportion of the mixed diet consisting of the less profitable item should decrease with an increase in both the size of the feeding group and the absolute profitability of the more profitable item, reflecting a trade-off between the need for a high rate of energy intake and the need to be vigilant for predators. Such behaviour was observed in free-living dark-eyed juncos (Junco hyemalis) feeding in simple two-prey environments.
Description of the oocysts of Isospora pachydactyli sp.nov. (Apicomplexa: Eimeriidae) from Bibron's gecko, Pachydactylus bibronii (Reptilia: Gekkonidae)
Authors: Upton Steve J. , Freed Paul S.
Published: September 2008

Isospora pachydactyli sp.nov. (Apicomplexa: Eimeriidae) is described from the feces of Pachydactylus bibronii bibronii from Namibia (South-West Africa). Oocysts sporulate endogenously and are spherical or subspherical, 27.4 × 27.1 (25.2–29.6 × 25.2–29.6) μm, with a bilayered wall ca. 1.5 μm thick; shape index (length/width) 1.0 (1.0–1.1). Micropyle, polar granule, and oocyst residuum are absent. Sporocysts are ovoid, 15.4 × 10.6 (14.4–16.8 × 9.6–11.2) μm, with Stieda and substieda bodies. The posterior end of the sporocyst is drawn out slightly to resemble a second Stieda body. Sporocyst residuum present, consisting either of a compact granular mass or of scattered granules. Sporozoites vermiform, with spherical anterior and posterior refractile bodies.
Predatory behavior of two species of ground beetles (Coleoptera: Carabidae) towards juvenile salamanders (Plethodon vehiculum)
Authors: Ovaska K. , Smith M. A.
Published: September 2008

Carabid beetles are suspected to prey on terrestrial salamanders, but no records of this exist. We examined the behavior of two species of ground beetle (Scaphinotus angusticollis and Pterostichus melanarius) towards juvenile western red-backed salamanders (Plethodon vehiculum) in staged laboratory encounters. We predicted that the beetles would show more aggression towards small (snout–vent length (SVL) ≤30 mm) than large (30 < SVL ≤ 40 mm) juvenile salamanders, as small individuals frequently had missing tails (indicating predation) in the field. Our additional objective was to examine antipredator behavior of P. vehiculum. Scaphinotus angusticollis approached, bit, and climbed on the salamanders more frequently than P. melanarius did, but neither beetle behaved differently towards small and large salamanders. Small juveniles jerked away more frequently than larger individuals when bitten by P. melanarius and when climbed on by S. angusticollis, but otherwise the behavior of salamanders of the two size classes did not differ. After overnight encounters, the injuries on the salamanders included missing toes and tail tips and skin lacerations. Scaphinotus angusticollis consumed an additional six P. vehiculum, and P. melanarius consumed three. The damage was unrelated to the size (SVL) of the salamanders, but all individuals consumed were among the smallest we tested. We suggest that in terms of both its morphology and its behavior, S. angusticollis is better suited than P. melanarius to prey on P. vehiculum, and probably preys on hatchlings in the wild.
The Simuliidae (Diptera) of Sri Lanka. Description of a new species of Simulium (Morops)
Authors: Davies D. M. , Györkös H.
Published: September 2008

This is the third paper in a series treating the Simuliidae of Sri Lanka; in it are described all stages of a new species of Simulium Latreille belonging to the subgenus Morops Enderlein, Simulium (Morops) trirugosum sp. nov. This is the first species of Morops found in Sri Lanka. Taxonomic comparisons are made with other Oriental species of the subgenus.
The effect of Bombylius pulchellus (Diptera; Bombyliidae) and other mortality factors upon the biology of Halictus ligatus (Hymenoptera; Halictidae) in southern Ontario
Authors: Packer Laurence
Published: September 2008

Two factors were important in causing brood mortality in a southern Ontario population of Halictus ligatus: parasitism by larvae of the bombyliid Bombylius pulchellus and various forms of microbial infection of bee immatures or their pollen ball food. Bombyliid larvae consumed host prepupae or, less commonly, young pupae, restricted their attack mostly to the reproductive brood, and were contagiously distributed within the nest population. All immature stages were susceptible to fungal infection or disease but such pathogens did not seem to spread among cells within nests, indicating that bees may be able to prevent the spread of disease from one brood cell to another. Filling affected cells with earth may accomplish this brood hygiene. The survival rate of worker and reproductive brood immatures approximated 90%. Reproductive brood mortality affected females more than males. Reproductive brood mortality was probably underestimated: filled-in cells that may represent brood mortality were not included in these estimates.
Helminth parasites of redfish (Sebastes fasciatus) from the Scotian Shelf, Bay of Fundy, and eastern Gulf of Maine
Authors: Scott J. S.
Published: September 2008

Examination of alimentary tracts of 319 redfish (Sebastes fasciatus) from the Scotian Shelf, Bay of Fundy, and eastern Gulf of Maine yielded 13 helminth species: 7 Digenea, 3 Cestoda, 2 Nematoda, and 1 Acanthocephala. Total species composition was virtually identical with that found in the redfish of the Labrador–Newfoundland area. Prevalence and intensity of infection were low and showed little variation with area or fish length except in the case of the nematodes Anisakidae for which low prevalence and intensity (3.9 and 1.0, respectively) in the eastern Gulf of Maine contrasted with higher values (39.1–71.4 and 1.7–7.7, respectively) in the remainder of the survey area. The general pattern of species numbers was low numbers (2–4) in the fish of the Gulf of Maine and southwest Nova Scotia, and higher numbers (8–13) in those of the central and northeast Scotian Shelf. Small- to intermediate-sized fish contained more species (7–12) than the largest fish (4). The combination of exceptionally low prevalence of Anisakidae and low parasite species numbers in redfish of the eastern Gulf of Maine area suggests that the stock there is distinct from those of the Scotian Shelf and Bay of Fundy.
Biology of the oribatid mite Mucronothrus nasalis (Acari: Oribatida: Trhypochthoniidae) from a small coldwater springbrook in eastern Canada
Authors: Norton Roy A. , Williams D. Dudley , Hogg Ian D. , Palmer Sandra C.
Published: September 2008

A population of the aquatic oribatid mite Mucronothrus nasalis, living in a cold, hardwater springbrook near Toronto, Canada, was sampled monthly from July 1985 to July 1986 using a Surber sampler. Of nine sampling locations situated along the full 60 m length of the springbrook, the source had by far the highest density of mites. Mites were most abundant in winter, reaching 1 individual/1.3 cm2 of substrate at the source, and least abundant in summer. Males were present, but uncommon, usually composing less than 10% of the adult population. Most collected females were gravid, regardless of season. Population age structure was inverted, with older instars being more abundant. There were no pulsed increases in density of immatures relative to adults, suggesting that reproduction is not strongly seasonal. Both adults and immatures appear to be generalized grazers on the "aufwuchs" community of unicellular and filamentous algae, fungi, and other organisms coating substrate surfaces, but also feed on decaying higher plant material. New geographic records show a transcontinental distribution in Canada, and the first records for the United States and Australia are given. Newly recorded habitat types include riverbeds and the profundal zone of lakes. Out of water behavior suggests that terrestrial dispersal is unlikely, supporting the hypothesis that the species predates the breakup of the supercontinent Pangea, with local distributions perhaps dating from Pleistocene events. The life history of this species appears more K-selected than that of another aquatic oribatid mite, Hydrozetes lemnae.
Forward flapping flight from flexible fins
Authors: Daniel Thomas L.
Published: September 2008

The mechanics and energetics of aquatic flight by the clearnose skate (Raja eglanteria) are examined with cinefilm and a new theoretical approach toward flight mechanics. Film analyses show that these animals move with a flapping, flexing wing that has a propulsive wave travelling rearward at twice the forward speed of the animal. A combination of blade-element theory and unsteady airfoil theory is used to examine the mechanics and energetics of this mode of locomotion. The theoretical analysis shows that (i) unsteady effects determine the overall performance of the wings, and (ii) there exist wing shapes that minimize the cost of transport or maximize the thrust. The theory indicates that the wings of swimming skates closely approach the minimum cost of transport. The results are extended to explore other modes of flapping wing propulsion, including those in animals whose wings deform passively in response to hydro- or aero-dynamic loads.
Effects of Arg–Phe-amide peptides on identified motor neurons in the hydromedusa Polyorchis penicillatus
Authors: Spencer Andrew N.
Published: September 2008

The effects were examined of several peptides (RFamide, FMRFamide, LPLRFamide, and pEGRFamide), all with the carboxy terminus Arg–Phe-amide, on the activity of partially isolated swimming motor neuron networks of the hydrozoan jellyfish Polyorchis penicillatus. Intracellular microelectrode recordings revealed the following responses to RFamide peptide solutions: an initial transitory hyperpolarization, which was often not present, followed by a long-duration (up to 3 min) excitation. Excitation was usually in the form of a spike train which increased rapidly in frequency and then decreased more slowly. Such spike trains were usually associated with an underlying depolarization and (or) a reduction in the spike after-hyperpolarization. The initial hyperpolarization was seen frequently with RFamide (supplied by Bachem), FMRFamide, and FLRFamide. This latter response could be partially accounted for by the acidity of the solutions. The order of effectiveness in eliciting excitation was: pEGRFamide (Anthopleura peptide), RFamide, FMRFamide, LPLRFamide, and FLRFamide. The effect of concentration on this response was examined for pEGRFamide. The responses described are interpreted in terms of possible conductance changes.
Robustocheles occulta sp.n., a new troglobitic mite (Acari: Prostigmata: Rhagidiidae) from North American caves
Authors: Zacharda Miloslav , Pugsley Chris W.
Published: September 2008

A troglobitic rhagidiid mite Robustocheles (Lewia) occulta sp.n. is described from three North American caves in Alberta, Washington, and Iowa. A subglacial refugium hypothesis is discussed in light of the unusual geographic distribution of this species.
Pivotal temperatures for loggerhead turtles (Caretta caretta) from northern and southern nesting beaches
Authors: Mrosovsky N.
Published: September 2008

The pivotal incubation temperature (that giving 50% of each sex) was estimated for two clutches of eggs from loggerhead sea turtles (Caretta caretta) nesting in each of three areas along the east coast of the United States: North Carolina, Georgia, and southern Florida. All pivotal temperatures were close to 29.0 °C. There was a significant difference between the pivotal temperatures of the two clutches from Florida. As an index of beach temperature, data on incubation durations in the three areas were collated and analysed: even during the warmest part of the season, incubation took about 6 days longer in North Carolina than in Georgia, and about 10–14 days longer than in Florida. Since there was no evidence that pivotal temperatures in North Carolina were lower than those of turtles nesting further south, it is likely that a higher percentage of males are produced on the North Carolina beaches, but data on pivotal temperatures of additional clutches are needed before this prediction can be made with confidence. The possible use of incubation duration for estimating sex ratios of hatchlings is discussed.
Spacing and habitat use of capercaillie during summer
Authors: Rolstad Jørund , Wegge Per , Larsen Bjørn Bjerke
Published: September 2008

We radio-tracked 52 capercaillie males and 21 broodless females during June, July, and August, 1979–1986, in a 100-km2 coniferous forest in central Scandinavia. After display activity ceased in early June, 77% of adult males made distinct movements, averaging 1.5 km, from lek territories to summer ranges. A similar movement was made by 48% of the females after loss of nest or brood. Males were now nonterritorial, and lived solitarily in overlapping home ranges averaging 170 ha. In June and July, they used successional stages in proportion to availability, but in August they preferred old, natural forest. Females, having home ranges averaging 103 ha, commonly formed small social groups of two to four individuals. They preferred young plantations throughout summer, and also preferred denser habitats than males. Both sexes returned to the same summer ranges in consecutive years. Home ranges of both sexes were distributed in a clumped spacing pattern. This can be explained by preference for patchily distributed habitat types in males, and habitat preference and sociality in broodless females.
Observations on the seaward migration of Atlantic salmon (Salmo salar L.) smolts through a large lake as determined by radiotelemetry and Carlin tagging studies
Authors: Bourgeois C. E. , O'Connell M. F.
Published: September 2008

Seaward movements of Atlantic salmon (Salmo salar L.) smolts through Red Indian Lake were studied using radiotelemetry and Carlin tagging. Movements of smolts through the lake occurred between the hours of 20:00 and 04:30 as determined from radiotelemetry. Carlin tagging revealed a net swimming speed ranging from 1.8 to 15.6 km/day; radiotelemetry revealed a rate of <1.0 to 11.2 km/day. Smolt movement through Red Indian Lake and other large insular Newfoundland lakes might be achieved through active migration as opposed to passive displacement. This aspect is discussed in the context of insular Newfoundland stocks for which extensive use of lakes by juveniles for rearing has been demonstrated.
The effect of food supply on the composition of Black-billed Magpie eggs
Authors: Hochachka Wesley M.
Published: September 2008

Viability of hatching birds may be affected by the composition of the eggs from which they come. Egg composition may be influenced by the diet of the female. I examined whether wild Black-billed Magpies (Pica pica) varied the composition of their eggs in response to differences in food supply. Supplemental food was provided on some territories, and the composition of eggs from control and food-supplemented territories was compared. Supplemental feeding had few effects on egg composition. Egg size – water content relationships differed between eggs from food-supplemented and control territories and there was a greater variability in yolk and shell mass within clutches from food-supplemented territories. These results show that food supply to the female can affect the composition of an egg relative both to other eggs in the same clutch and to eggs in other clutches. However, it is not clear whether the observed variation in egg composition would have an effect on the viability of the eggs.
Éléments pour la cartographie écologique de l'échinococcose alvéolaire dans le Massif central (France): essai de délimitation d'un foyer
Authors: Gilot B. , Doche B. , Deblock S. , Pétavy A. F.
Published: September 2008

A centre of alveolar disease caused by Echinococcus multilocularis has recently been discovered in the Department of Cantal, France; we have attempted to define the limits of the centre of infection and to determine the main risk zones of propagation of the disease. The red fox, Vulpes vulpes (L.), served as a marker of the parasite. Ecological factors (floristic, climatological, and lithological) and parasitological results were compared. Ecological analysis was used to characterize 11 zones distributed among three stages of vegetation. Two zones are propitious for the life cycle of the cestode : beech series on volcanic soil and locally acidophilous beech series on metamorphic soil. The vegetation types may be used as ecological indicators in the definition of the distribution of E. multilocularis in France.
Evidence of polygyny from spatial patterns of hooded seals (Cystophora cristata)
Authors: Boness Daryl J. , Bowen W. Don , Oftedal Olav T.
Published: September 2008

Based on scant empirical data, the mating system of the hooded seal (Cystophora cristata) has been variously characterized as monogamous or polygynous. To evaluate the hypothesis that female hooded seals are clustered to a degree that would facilitate polygyny, we collected data on the spatial dispersion of female and male seals on the ice floes off the Labrador coast. While flying from a ship at the edge of the seal herd to a study site within the herd, we recorded each sighting of female seals as a "solitary female" or a "cluster of females" (using an approximate 10 body length radius to differentiate these conditions). The numbers of males near females were also recorded. Nearest-neighbor distances were obtained during on-ice transects. The frequency of nearest-female-neighbor distance classes peaked at 6–10 seal body lengths (one body length = 1.9–2.6 m) and then declined to distances of greater than 25 body lengths. About 40% of 357 females with pups (or 22% of 279 sightings of seals) were in clusters consisting of two or more mother–pup pairs; the maximal cluster size observed was five. The majority of females or clusters of females had a single male in attendance (54% of 245 sightings). Females in the central part of the herd were both clustered and attended by males more often than were females at the periphery. Observations of a few marked males suggested that some took up positions near additional females when their original female companions departed. These results are consistent with the hypothesis that the spatial pattern of hooded seals should facilitate polygyny.
Induction of anemia in goldfish, Carassius auratus L., by immersion in phenylhydrazine hydrochloride
Authors: Houston A. H. , Murad A. , Gray J. D.
Published: September 2008

Immersion of goldfish, Carassius auratus, in 1 mg∙L−1 phenylhydrazine hydrochloride at 5 °C for 48 h led to reductions of 90–95% in hemoglobin and hematocrit within 10–14 days. Under similar conditions, 96-h exposures prompted heavy mortality. Fewer mortalities occurred after 24-h exposure periods; however, only modest reductions in O2-carrying capacity were seen. All higher concentration (2, 5, 10, 50 mg∙L−1) and temperature (10, 15, 20 °C) combinations led to complete mortality within 12–96 h regardless of exposure period (24, 48, 96 h). Exposure to phenylhydrazine hydrochloride caused decreases in hemoglobin and hematocrit, changes in the abundances of specific hemoglobin isomorphs, and the transient appearance of novel hemoglobin mobilities as well as evidence of osmo- and iono-regulatory dysfunction. Slow warming to 20 °C prompted red cell proliferation and hemoglobin synthesis and restoration of typical hemoglobin isomorph abundances. Incidence of transfer stresses was monitored by reference to differential leucocyte counts. Transfer led to lymphopenia and thrombopenia with neutrophilia and eosinophilia. Warming was accompanied by increases in lymphocyte and thrombocyte counts and reductions in those of monocytes and all granulocytes.
Summer ichthyoplankton communities of two estuarine systems of Prince Edward Island
Authors: Johnston C. E. , Morse M.
Published: September 2008

Fish eggs and (or) larvae representing 22 species in 14 families were collected during the summer of 1983 at eight stations in the Hillsborough River estuary – Northumberland Strait area and three stations in the Tracadie Bay – Gulf of St. Lawrence region. Of the 62 287 eggs collected, 83.5% were either yellowtail flounder, Limanda ferruginea, or cunner, Tautogolabrus adspersus, and 5.9% were Atlantic mackerel, Scomber scombrus. The most abundant larvae were alewife, Alosa pseudoharengus, Atlantic mackerel, and cunner accounting for 24.6, 22.4, and 20.6%, respectively, of the total 5077 larvae and juveniles collected. The highest average concentration of eggs and larvae occurred in the coastal area near Tracadie Bay (4265 eggs/100 m3, 350 larvae/100 m3), in the Northumberland Strait region (2682 eggs/100 m3), and at the head of the Hillsborough River system (170 larvae/100 m3). The greatest species diversity occurred near Tracadie Bay (5.0 species of larval fish per tow) and in Tracadie Bay channel (4.0 species of larval fish, 6.0 species of eggs per tow). Summer variations in abundance and distribution were correlated with water temperature and salinity for the more abundant species (alewife, cunner, Atlantic mackerel, Gasterosteus aculeatus, Morone americana, Osmerus mordax, Menidia menidia, Pseudopleuronectes americanus). Species associations and station assemblages were analyzed using the Bray – Curtis dissimilarity measure and a numerical classification system.
The breeding success of common loons (Gavia immer) in relation to alkalinity and other lake characteristics in Ontario
Authors: Alvo Robert , Hussell David J. T. , Berrill Michael
Published: September 2008

We examined the breeding success of common loons (Gavia immer) and made observations of loons feeding their young on small lakes (5.3–75 ha) with different alkalinities (−73 to 1804 μequiv./L) near Sudbury, Ontario. Alkalinity, pH, and conductivity were highly correlated with each other. There was a significant positive relationship between successful breeding and alkalinity on 68 lakes surveyed in 1982. Discriminant analysis showed that alkalinity, area, and colour of the lake contributed significantly to discrimination among lakes with successful, unsuccessful, and no breeding attempts. Lack of a breeding attempt tended to be associated with small, brown, low-alkalinity lakes, and successful breeding with large, clear, high-alkalinity lakes. For lakes with breeding attempts in 1982–1984, alkalinity (all years), depth (1983), and area (1984) provided significant discrimination between unsuccessful lakes and those on which young were raised. Unsuccessful breeding resulted primarily from brood mortalities on acidic lakes. Adult loons were more successful at securing fish on high-alkalinity lakes than on low-alkalinity lakes, and this may reflect differences in fish densities. A pair of loons attempting to raise a chick on a fishless, acidic lake fed the chick benthic algae and possibly benthic invertebrates, but flew to other lakes to feed themselves. We suggest that the high level of brood mortalities on acidic lakes resulted from a shortage of suitable food for the young.
Seasonal partitioning of atympanate moths in relation to bat activity
Authors: Yack Jayne E.
Published: September 2008

Certain families of atympanate (deaf) moths are more abundant during the summer at times when bat activity is low. Atympanate moths were collected at ultraviolet lights throughout the summer at a site in southeastern Ontario. Seasonal frequency distributions for individual families showed different trends when compared with ambient bat activity levels. Most saturniids were collected between mid-May and mid-June, before the time when bats are most active (July and August). Lasiocampids were also collected outside the range of high bat activity, emerging in early May, late June, or late August. Population levels of the sphingids, on the other hand, were similar to bat activity levels. From these data, I suggest that some families of deaf moths face reduced selection pressure by bats through temporal isolation.
A food delivery system for laboratory streams
Authors: Reeves Gordon H. , Everest Fred H.
Published: September 2008

We describe a simple and inexpensive food delivery system for use in laboratory streams. The pattern of food delivery from the system results in normal behavior and distribution of territorial fish within the stream.
Use of phenylhydrazine in the detection of responsive changes in haemoglobin isomorph abundances
Authors: Byrne Annette P. , Houston A. H.
Published: September 2008

The possible masking of responsive adjustments in hemoglobin isomorph abundances was examined in rainbow trout, Salmo gairdneri. Comparison of untreated animals with specimens recovering from anemia induced by phenylhydrazine hydrochloride at 14 °C under normoxic circumstances revealed significant differences in the relative abundances of 8 of 12 isomorphs representing over half of the total hemoglobin complement. Comparisons with trout similarly treated after normoxic acclimation to 20 °C led to very similar findings. Observed differences do not appear to be attributable to direct phenylhydrazine effects on globin gene expression or to acute anemic hypoxia. It is suggested that prior induction of anemia may provide a means for improving detection of changes in hemoglobin isomorph complement during respiratory response to environmental change.
FAMILY OF INVARIANT CANTOR SETS AS ORBITS OF DIFFERENTIAL EQUATIONS
Authors: CHEN YI-CHIUAN
Published: September 2008

The invariant Cantor sets of the logistic map gμ(x) = μx(1 - x) for μ > 4 are hyperbolic and form a continuous family. We show that this family can be obtained explicitly through solutions of initial value problems for a system of infinitely coupled differential equations due to the hyperbolicity. The same result also applies to the tent map Ta(x) = a(1/2 - |1/2 - x|) for a > 2.
BIFURCATION AND CHAOS IN THE FRACTIONAL-ORDER CHEN SYSTEM VIA A TIME-DOMAIN APPROACH
Authors: CAFAGNA DONATO , GRASSI GIUSEPPE
Published: September 2008

This tutorial investigates bifurcation and chaos in the fractional-order Chen system from the time-domain point of view. The objective is achieved using the Adomian decomposition method, which allows the solution of the fractional differential equations to be written in closed form. By taking advantage of the capabilities given by the decomposition method, the paper illustrates two remarkable findings: (i) chaos exists in the fractional Chen system with order as low as 0.24, which represents the smallest value ever reported in literature for any chaotic system studied so far; (ii) it is feasible to show the occurrence of pitchfork bifurcations and period-doubling routes to chaos in the fractional Chen system, by virtue of a systematic time-domain analysis of its dynamics.
A MODIFIED CHUA'S CIRCUIT WITH AN ATTRACTION-REPULSION FUNCTION
Authors: LI RONG , DUAN ZHISHENG , WANG BO , CHEN GUANRONG
Published: September 2008

In this paper, the original Chua's circuit is modified by substituting its piecewise-linear function with an attraction-repulsion function. Some new complex dynamical behaviors such as chaos are observed through computer simulations. Basic properties of the new circuit are analyzed by means of bifurcation diagrams. Lagrange stability conditions of the circuit are derived. A comparison between this modified Chua's circuit with an attraction-repulsion function and the modified Chua's circuit with a cubic nonlinear function is presented. Moreover, a generalization of the new circuit that can generate multiple scrolls is designed and simulated. Finally, a physical circuit is built to visualize the new system, with some experimental observations reported.
CONTINUATION OF CONNECTING ORBITS IN 3D-ODEs (I): POINT-TO-CYCLE CONNECTIONS
Authors: DOEDEL E. J. , KOOI B. W. , VAN VOORN G. A. K. , KUZNETSOV YU. A.
Published: September 2008

We propose new methods for the numerical continuation of point-to-cycle connecting orbits in three-dimensional autonomous ODE's using projection boundary conditions. In our approach, the projection boundary conditions near the cycle are formulated using an eigenfunction of the associated adjoint variational equation, avoiding costly and numerically unstable computations of the monodromy matrix. The equations for the eigenfunction are included in the defining boundary-value problem, allowing a straightforward implementation in AUTO, in which only the standard features of the software are employed. Homotopy methods to find connecting orbits are discussed in general and illustrated with several examples, including the Lorenz equations. Complete AUTO demos, which can be easily adapted to any autonomous three-dimensional ODE system, are freely available.
SHILNIKOV BIFURCATION: STATIONARY QUASI-REVERSAL BIFURCATION
Authors: CLERC MARCEL G. , ENCINA PABLO C. , TIRAPEGUI ENRIQUE
Published: September 2008

A generic stationary instability that arises in quasi-reversible systems is studied. It is characterized by the confluence of three eigenvalues at the origin of complex plane with only one eigenfunction. We characterize the dynamics through the normal form that exhibits in particular, Shilnikov chaos, for which we give an analytical prediction. We construct a simple mechanical system, Shilnikov particle, which exhibits this quasi-reversal instability and displays its chaotic behavior.
OSCILLATIONS AND CHAOS IN SIMPLE QUADRATIC SYSTEMS
Authors: INNOCENTI G. , GENESIO R. , GHILARDI C.
Published: September 2008

This paper is concerned with the study of third order quadratic and autonomous systems and the interest is oriented to the stable periodic oscillations. From the "jerk" equation model, the classes of minimal complexity presenting a Hopf bifurcation are derived and their local characterization is carried out by means of a suitable harmonic balance technique. Other possible system reductions preserving the oscillations are studied and the numerical analysis confirms the obtained results. Some bifurcations and related routes to chaos are also exhibited by these simple systems. A comparison with previous results on the subject is also presented.
ON THE NUMBER AND DISTRIBUTIONS OF LIMIT CYCLES IN A QUINTIC PLANAR VECTOR FIELD
Authors: WU YUHAI , GAO YONGXI , HAN MAOAN
Published: September 2008

This paper is concerned with the number and distributions of limit cycles in a Z2-equivariant quintic planar vector field. By applying qualitative analysis method of differential equation, we find that 28 limit cycles with four different configurations appear in this special planar polynomial system. It is concluded that H(5) ≥ 28 = 52+ 3, where H(5) is the Hilbert number for quintic polynomial systems. The results obtained are useful to the study of the second part of 16th Hilbert problem.
A BIFURCATION ANALYSIS OF A 3D BLOWFLY MODEL IN DISCRETE AND CONTINUOUS TIME
Authors: HÜLS THORSTEN
Published: September 2008

In this paper, we extend the two-dimensional discrete time model of the virtual fly, developed by Böddeker and Egelhaaf [2003], into three space dimensions, and introduce its continuous time analog. Like real blowflies, the virtual counterparts exhibit a dichotomous chasing behavior: depending on size, velocity and the course of the targets; they catch the targets or pursue them at constant distance. Here, we analyze this behavioral characteristic with respect to the course of the target, in particular, we choose trajectories, spiraling upwards. After setting up the three-dimensional model, we transform it into the local coordinates of the pursuer, using equivariance properties. Then bifurcation tools apply, and it turns out that depending on the gradient and the curvature of the spiraling trajectory, a fixed point in the transformed system can lose or gain stability. A stable fixed point corresponds in the original system to a trajectory, on which the virtual fly follows the target at a constant distance. In this way, we explain the dichotomous behavior through the occurrence of bifurcations.
THE HARMONIC BALANCE TECHNIQUE ANALYSIS OF OPEN QUANTUM SYSTEMS
Authors: CIVALLERI PIER PAOLO , GILLI MARCO , BONNIN MICHELE
Published: September 2008

The Harmonic Balance Technique (HBT) is used to analyze the steady state performance of a two-state quantum system interacting with a classical sinusoidal electromagnetic wave and with a thermal bath at a fixed temperature. The linear time-variant differential equations describing such a system can be solved to any number of harmonics and the results can be compared with those obtained with the classical RWA approximation, thus emphasizing the validity limits of the latter.
PROPAGATION PROPERTIES OF BI-COUPLED NONLINEAR OSCILLATORY CHAINS: ANALYTICAL PREDICTION AND NUMERICAL VALIDATION
Authors: ROMEO FRANCESCO , REGA GIUSEPPE
Published: September 2008

Harmonic wave propagation in one-dimensional chains of nonlinear oscillators are investigated by means of nonlinear maps. The study extends previous results obtained for the mono-coupled oscillators to bi-coupled ones. The considered bi-coupled model refers to a chain of linearly coupled mechanical oscillators characterized by on-site cubic nonlinearities in both the longitudinal and rotational degrees of freedom. Pass, stop and complex regions are analytically determined for period-q orbits as they are governed by the eigenvalues of the linearized map arising from the relevant linear stability analysis. By varying the parameters governing both the coupling between the two d.o.f. and the nonlinearity, a variable scenario of propagation regions can be obtained, which includes the limit case of mono-coupled behavior. Theoretical predictions are validated through numerical results in terms of orbits, bifurcation diagrams and basins of attraction, obtained via nonlinear map iteration. They highlight a rich variety of regular and nonregular bounded solutions.
COMPLETE CLASSIFICATION OF EQUILIBRIA AND THEIR STABILITY IN A DELAYED NEURON NETWORK
Authors: CHEN YUMING , WU JIANHONG
Published: September 2008

We consider the following system of delay differential equations [Formula: see text] where i (mod 3), and S(x) is the hyperbolic tangent function. The system models the evolution of a network of three identical neurons with delayed feedback. We provide a full classification of all equilibria and their stability in the (α,τ)-parameter space. Such a classification is essential for the description of spatio-temporal patterns of the model system and for the applications to dynamic memory storage and retrieval.
IMPROVED SUFFICIENT CONDITIONS FOR GLOBAL EXPONENTIAL STABILITY OF RECURRENT NEURAL NETWORKS WITH DISTRIBUTED DELAYS
Authors: WU WEI , CUI BAO TONG , ZENG ZHIGANG
Published: September 2008

In this paper, the globally exponential stability of recurrent neural networks with continuously distributed delays is investigated. New theoretical results are presented in the presence of external stimuli. It is shown that the recurrent neural network is globally exponentially stable, and the estimated location of the equilibrium point can be obtained. As typical representatives, the Hopfield neural network (HNN) and the cellular neural network (CNN) are examined in detail. Comparison between our results and the previous results admits the improvement of our results.
IDENTIFICATION OF n-STATE SPATIO-TEMPORAL DYNAMICAL SYSTEMS USING A POLYNOMIAL MODEL
Authors: GUO YUZHU , BILLINGS STEVE A. , COCA DANIEL
Published: September 2008

A multivariable polynomial model is introduced to describe n-state spatio-temporal systems. Based on this model, a new neighborhood detection and transition rules determination method is proposed. Simulation results illustrate that the new method performs well even when the patterns are corrupted by static and dynamical noise.
AN IRREVERSIBLE PROCESS REPRESENTED BY A REVERSIBLE ONE
Authors: BOYARSKY ABRAHAM , GÓRA PAWEŁ
Published: September 2008

Chaotic maps on an interval are irreversible in the sense that trajectories of points cannot be reversed. Furthermore, even when one considers trajectories of probabilities or probability density functions (pdf) generated by the chaotic map, the processes are irreversible. In this note we consider the following question: let τ be a chaotic map which takes a pdf f0 to a pdf f1. Does there exist a reversible process that accomplishes the same thing. For example, can we construct a differential equation which takes f0 to f1 and then, on reversal of time, f1 to f0. We present an example which answers this question in the affirmative.
EFFECTS OF THE SHAPE OF PERIODIC FORCES ON STOCHASTIC RESONANCE
Authors: GANDHIMATHI V. M. , RAJASEKAR S. , KURTHS J.
Published: September 2008

We study the influence of the shapes of three different external periodic forces on the stochastic resonance phenomenon in multiple potential well systems with Gaussian noise. We consider as external periodic forces the sine wave, the modulus of sine wave and the rectified sine wave. The systems of our interest are two coupled overdamped anharmonic oscillators and the Duffing oscillator. For fixed values of the parameters, when the intensity D of the external noise is varied, the systems with these periodic forces separately are found to exhibit stochastic resonance. Certain similarities and differences are found in the characteristics of these statistical measures such as signal-to-noise ratio (SNR), response amplitude (Q), time series plot, mean residence time τMR in the potential wells and the distribution P of the normalized residence time for these different forces. Especially, the time series plot at the maximum SNR shows an almost periodic switching between the potential wells for the sine force which is not observed for the other two forces. In the noise-induced intermittent dynamics, τMR is the same in different wells for the sine force, whereas it is different in different wells for the other two forces for each value of the noise intensity D. Further, variation of τMR with D, the value of τMR at the resonance and the distribution P show different features for the different types of forces. We present a detailed comparative study and explanation for the similarities and differences observed in the stochastic resonance dynamics.
GENERATION OF A FOUR-WING CHAOTIC ATTRACTOR BY TWO WEAKLY-COUPLED LORENZ SYSTEMS
Authors: GRASSI GIUSEPPE , SEVERANCE FRANK L. , MASHEV EMIL D. , BAZUIN BRADLEY J. , MILLER DAMON A.
Published: September 2008

This paper presents a novel chaotic four-wing attractor generated by coupling two identical Lorenz systems. An analysis of the proposed system shows that its equilibria have certain symmetries with respect to specific coordinate planes and the eigenvalues of the associated Jacobian matrices exhibit the property of similarity. In analogy with the original Lorenz system, where the two wings of the butterfly attractor are located around the two equilibria with the unstable pair of complex-conjugate eigenvalues, this paper shows that the four wings of this new attractor are located around four equilibria with four unstable complex-conjugate eigenvalues. A generalization of the proposed system to realize an eight-wing attractor is also described.
HOPF BIFURCATION AS AN INTERMEDIATE-SCALE INSTABILITY IN SINGLE-STAGE POWER-FACTOR-CORRECTION POWER SUPPLIES: ANALYSIS, SIMULATIONS AND EXPERIMENTAL VERIFICATION
Authors: DAI DONG , TSE CHI K. , ZHANG BO , MA XIKUI
Published: September 2008

This paper reports intermediate-scale instability in a single-stage power-factor-correction (PFC) power supply that employs a cascade configuration of a boost stage operating in discontinuous conduction mode (DCM) and a forward stage operating in continuous conduction mode (CCM). The two stages combine into a single stage by sharing one main switch and one control loop to achieve input PFC and tight output regulation. The main results are given by "exact" cycle-by-cycle circuit simulations. The effect of the intermediate-scale instability on the attainable power factor is illustrated in terms of total harmonic distortion (THD) which is found by taking the Fast Fourier Transform (FFT) of the input current. The intermediate-scale instability usually manifests itself as local oscillations within a line cycle. Based on the stability analysis of a buck converter operating in CCM, the underlying mechanism of such instability can be attributed to the Hopf bifurcation that occurred in CCM forward stage. Finally, experimental results are presented for verification purposes.
NETWORKS OF COMMUNITIES AND EVOLUTION OF COOPERATION
Authors: DORAT R. , DELAHAYE J. P.
Published: September 2008

In this paper, we propose a new very simple mechanism supporting the emergence of cooperation in a population of memoryless agents playing a prisoner's dilemma game. Each agent belongs to a community and interacts with the agents of its community and with the agents belonging to linked communities. A simple rule governs the dynamics of the system: a community grows (resp. decreases) if the average score of its members is superior (resp. inferior) to the average score calculated for the entire population. Starting from a random initialization, the system can evolve towards a majority of cooperators, towards the elimination of cooperators, or towards a situation with periodic evolutions of the populations of cooperators and defectors. The initial presence of clusters of C-strategies accounts for the convergence towards cooperative final states. We consider various topologies: Erdös and Rényi random graphs, square lattices and scale-free graphs. Clusters are not as likely to appear in all these topologies, so that there are significant differences between the average frequencies of cooperators associated with each topology. We show that random graphs favor cooperation whereas scale-free graphs tend to inhibit it. The relation between periodic evolutions and topological features is less clear. Nonetheless, we also state the importance of specific C-clusters for the survival of C-strategies in periodic oscillations. A major lesson of this paper is that the evolution of cooperation is very sensitive to initial conditions in models with global variables.
CHAOS IN TWO-PARTY DEMOCRACIES
Authors: COLOMBO ALESSANDRO , RINALDI SERGIO
Published: September 2008

In two-party democracies (e.g. US and UK) the two parties often alternate at the government almost periodically. Here, we present a very simple continuous-time model with three state variables (social welfare and size of the lobbies associated with the two parties) that explains this tendency to cyclic behavior. However, the analysis of the model shows that when the lobbies are unbalanced, much more complex behaviors, including chaos, can emerge. The bifurcation structure of the system is interesting: it contains a countable number of codimension-2 points (associated with pseudo-equilibria of a particular Filippov system) which are the roots of Arnold tongues delimited by two border collision bifurcations, and in each one of these tongues the sequence of the parties at the government is a particular periodic sequence.