bluuebunny/crossref_metadata_2025 huggingface dataset:
Diversity and distribution of the orthopteroid insects of the Galápagos Islands, Ecuador
Authors: Peck Stewart B.
Published: May 2008

New fieldwork has brought the entire "orthopteroid" fauna of the Galápagos Islands to a total of 57 species, in 37 genera, and 7 insect orders. Identification keys and distributional details are given for the 24 species in the order Orthoptera (s.str.) (Ensifera and Caelifera). Of these, 19 species (and 2 genera) are endemic, 2 species are native (naturally occurring elsewhere in tropical America), and 3 species are presumed to have been introduced by humans. It is assumed that ancestral natural colonizations occurred through the air by flying ancestors or through rafting and ocean-surface transport by flightless ancestors (in Gryllidae; Nemobiinae and Mogoplistinae). Of the indigenous (non-introduced) species, 71% of Orthoptera (s.str.) and 72% of all orthopteroids of the Galápagos Islands are now flightless in one or both sexes. Considering the richness of the total orthopteroid fauna in mainland Ecuador, the island fauna is very highly impoverished. Evolution and diversification are modest in the Galápagos orthopteroids compared with some other plants and animals. Some species (probably descendant from coastal arid zone ancestors) are now limited to either moist highland or cave habitats. Species richness is significantly positively correlated with island ecological complexity and island area.
Response by wolves to prey variation in central Ontario
Authors: Forbes G. J. , Theberge J. B.
Published: May 2008

The influence of variation in prey availability in a wolf–moose–deer–beaver predator–prey community was studied from 1987 to 1992 in Algonquin Park, Ontario, Canada. Density, food habits, and movements of 57 radio-collared gray wolves (Canis lupus) were compared among three regions of varying moose (Alces alces) and white-tailed deer (Odocoileus virginianus) spatial and temporal abundance. Relative moose and deer availability was determined annually from 16 track surveys (5 km each), 150 pellet surveys (300 × 2 m), stratified aerial surveys (2 or 3 each winter), and prey carcass data. One region contained high moose abundance and virtually no deer year-round. The second region had high moose levels with moderate levels of deer, and a third region varied in deer winter abundance annually. Wolf use of deer was high, based on the proportion of deer in winter scats (9.3–32.1% frequency of occurrence; 4.3–22.5% total biomass) and the number of deer predation cases (50 carcasses) that occurred in all three regions, even in areas where deer were considered to be very rare. Wolf use of deer was positively correlated with increases in winter deer abundance (r2 = 0.66). Wolf density correlated with deer numbers (r2 = 0.74). In winter, deer in the third region migrated to a deer yard 15 km from Algonquin Park. A remaining overwintering deer density of less than 0.02/km2appears to have prompted a movement of wolves to the deer yard. Of the 41 moose consumed by wolves in winter, most (71%) were scavenged animals that had died with infestations of winter tick (Dermacentor albipictus). Beaver (Castor canadensis) apparently acted as important buffer prey species when deer numbers were low. The Algonquin wolf's reliance on smaller prey items appears to be a function of the fluctuating prey base, which promotes alternative hunting strategies, and the small size of the Algonquin wolf, which makes it an inefficient predator of moose. Even though moose were relatively constant in availability, and a major food item, the wolf population was responding primarily to the availability of deer.
Reproductive effort of male hooded seals (Cystophora cristata): estimates from mass loss
Authors: Kovacs Kit M. , Lydersen Christian , Hammill Mike , Lavigne David M.
Published: May 2008

This study investigated mass loss, body composition, and behaviour patterns of male hooded seals during the reproductive season. During the 6 years of study (between 1989 and 1995), 139 records of male mass were obtained that involved 115 individuals. Body masses of males ranged from 147 to 434 kg. Mean mass at first capture was 312.5 ± 53.0 kg (N = 119). Year, date of sampling, and age all significantly influenced mass. Nineteen males were recaptured at least twice during a single season. Mean rate of mass loss among these individuals was 2.5 ± 1.1 kg/day (range 0.7–4.6 kg/day). Body composition early in the breeding season, measured using tritiated water (N = 6), produced mean estimates of 51.6 ± 1.6% water, 29.3 ± 2.4% fat, 16.9 ± 0.7% protein, and 1.9 ± 0.2% ash. Time–depth recorders attached to three males indicated that they spent 84.7 ± 15.4% of their time hauled out on the surface of the ice during the breeding season. Each of these males was on the ice for a few days; they then spent a few hours at sea before returning to the ice surface. Mean dive depth was only 14.1 ± 3.2 m (maximum 66 m) and mean dive duration was only 1.7 ± 0.3 min (maximum 28 min). Extrapolating mean daily rates of body mass loss to encompass a 2.5-week breeding season, males would lose an average of 44 kg, which represents 14% of their mean body mass. Compared with values for males of other phocid species this value is conservative. It appears that the short breeding season among hooded seals is energetically advantageous for both sexes.
Ringed seal diving behavior in the breeding season
Authors: Kelly Brendan P. , Wartzok Douglas
Published: May 2008

The behavior of 14 ringed seals (Phoca hispida) diving under shore-fast sea ice was monitored acoustically during the spring breeding season. Frequent dives with extended periods at depth by subadult and adult seals, including lactating females, were interpreted to be foraging dives. Median dive durations were less than 10.0 min for all seals, and the maximal observed duration was 26.4 min. The maximal observed dive depth, 222 m, was limited by water depth in the study area. Modal dive depths were between 10 and 45 m for breeding-age males and between 100 and 145 m for subadult males and postparturient females. Median dive durations were 4.0 min for adult males and 7.5 min for adult females. Body mass was a better predictor of maximal dive duration (r2 = 0.94) than was age, but maximal durations were shorter than were predicted using measures of oxygen stores and presumed metabolic rates. There was no consistent relationship between light level and the frequency or depth of dives.
Morphological and cytological observations on two opalinid endocommensals of Acanthixalus spinosus (Amphibia, Anura)
Authors: Affa'a Félix-Marie , Mignot Jean-Pierre , Amiet Jean-Louis
Published: May 2008

The morphology and cytology of two new opalinid species were studied using silver impregnation and fixation, which preserves the microfibrils. Both species, commensal on Acanthixalus spinosus, are host-specific. Light microscopy showed the existence of a posterior secant system in Opalina proteus n.sp. and its absence in Cepedea couillardi n.sp. (in agreement with the differences presently recognised between the two genera). At the ultrastructural level, however, both species present a posterior fibrillar zone that seems to be homologous with the secant system. This apparent contradiction may be explained by the fact that the secant system is visible under light microscopy only in O. proteus because its fibrillar zone is more developed than in C. couillardi. The life cycle of C. couillardi spans stages from the tadpole to the adult; in contrast, O. proteus completes its cycle before metamorphosis of the host.
The abundance and effects of ticks (Ixodes uriae) on nestling Cassin's Auklets (Ptychoramphus aleuticus) at Triangle Island, British Columbia
Authors: Morbey Y. E.
Published: May 2008

Cassin's Auklet (Ptychoramphus aleuticus) nestlings hosted the common seabird tick Ixodes uriae. This is a new host record for this species of tick. Ixodes uriae were distributed nonrandomly on nestlings within and among sites. Soil substrate was thought to be an important factor influencing tick distribution. Nestlings with severe tick infestation had slower rates of wing growth, reached peak mass at older ages, and fledged with shorter wings at older ages than nestlings with fewer ticks. By remaining in the nest for longer periods, nestlings with severe tick infestation may have been compensating for the delay in wing development.
Size-related shift in feeding strategy and prey-size selection in young grayling (Thymallus thymallus)
Authors: Sempeski Philippe , Gaudin Philippe
Published: May 2008

Observations of feeding behaviour and analysis of prey-size selection by young grayling revealed a shift in feeding strategy coinciding with a shift in habitat occurring between larval (observed in lateral habitats) and juvenile (observed in the river channel) stages of grayling. The mean number of foraging attempts per minute decreased four times between both stages, while in the same time the mean distance travelled during each foraging attempt decreased from 1.5 body lengths to 1 body length. Gape-limited postemergent larvae fed mainly on small chironomid larvae (<0.5 mm3) but larger larvae and pupae (0.5 – 1 mm3) were consumed with increasing size. The diet spectrum of juveniles >40 mm was characterized by the appearance of very large prey (> 10 mm3), such as simuliid and ephemeropteran larvae, but also by a new increase of the contribution of small chironomid larvae. Changes in the feeding strategy of young grayling are discussed in relation to internal (e.g., morphological limitations) and external (e.g., physical characteristics of habitat) constraints.
Behavioural effects of exposure to underwater explosions in humpback whales (Megaptera novaeangliae)
Authors: Todd Sean , Lien Jon , Marques Fernanda , Stevick Peter , Ketten Darlene
Published: May 2008

Humpback whale (Megaptera novaeangliae) entrapment in nets is a common phenomenon in Newfoundland. In 1991 – 1992, unusually high entrapment rates were recorded in Trinity Bay on the northeast coast of Newfoundland. The majority of cases occurred in the southern portion of the bay close to Mosquito Cove, a site associated with construction operations (including explosions and drilling) that presumably modified the underwater acoustic environment of lower Trinity Bay. This study reports the findings of the resulting assessment conducted in June 1992 on the impact of the industrial activity on humpback whales foraging in the area. Although explosions were characterized by high-energy signatures with principal energies under 1 kHz, humpback whales showed little behavioural reaction to the detonations in terms of decreased residency, overall movements, or general behaviour. However, it appears that the increased entrapment rate may have been influenced by the long-term effects of exposure to deleterious levels of sound.
Hydroids (Cnidaria: Hydrozoa) recorded from depths exceeding 3000 m in the abyssal western North Atlantic
Authors: Calder Dale R.
Published: May 2008

Hydroid diversity and abundance appear to be low in the mid-abyssal zone of the western North Atlantic Ocean. Only two species (Acryptolaria longitheca,?Opercularella sp.) were collected during investigations by submersible (Deep Submergence Vehicle Alvin) at depths between 3011 and 3550 m along the northwest slope of the Bermuda Pedestal in March 1993. Moreover, bottom samples from 59 deep stations (all > 3000 m) between southern New England and Bermuda, collected by the Woods Hole Oceanographic Institution Benthic Ecology Program between 1961 and 1973, contained just two hydroid specimens (both referred here to Halisiphonia megalotheca). Of some 424 species of hydroids currently recognized from the western North Atlantic, only 8 have ever been reported in the region from depths exceeding 3000 m. One of these (Cryptolarella abyssicola) has been recorded from the North and South Atlantic, North and South Pacific, and Southern Ocean, and another (Halisiphonia megalotheca) from the North and South Atlantic, North and South Pacific, and southern Indian Ocean. The other six (Stylactaria ingolfi, Eucuspidella pedunculata, ?Opercularella sp., Halecium dubium, Acryptolaria longitheca, and Aglaophenopsis verrilli) have been reported exclusively from the North Atlantic. The hydroid fauna of the mid-abyssal zone may be sparse compared with that of neritic waters, but it is less frequently sampled and remains poorly known.
Male aggression and colour in divergent populations of the threespine stickleback: experiments with animations
Authors: McKinnon Jeffrey S. , McPhail J. D.
Published: May 2008

We investigated the evolution of male agonistic behaviour and nuptial coloration in populations of the threespine stickleback, Gasterosteus aculeatus, with either monomorphic red or monomorphic black coloration. Specifically, we examined the responses of males from the two population types to computer-generated animations of males with black, red, or dull grey throats on otherwise identically coloured bodies. Males varied greatly in their aggressive responses among individuals and among trials, and did not show statistically significant discrimination towards the differently coloured animations. These results, therefore, do not suggest a role for interactions among males in the evolution of divergent male nuptial coloration. In addition, these negative findings are consistent with other studies of stickleback from western North America, suggesting that geographic variation in agonistic colour discrimination may account, in part, for the discrepancies between the results of earlier studies. Given the diverse methods of studies on this topic, however, methodological differences may also have contributed to the inconsistent results.
Mantis movements by night and the interactions of sympatric bats and mantises
Authors: Cumming Graeme S.
Published: May 2008

Bat–insect interactions should be a useful source of case studies for the "arms race" of predator and prey adaptations; currently, well-detailed examples are needed for the formulation of general hypotheses. In this paper I add to information on bat–mantis interactions, testing four predictions of the hypothesis that mantises with ears can detect and avoid bats: that mantises will fly by night, that they will be vulnerable to bats, that echolocating bats will be better at catching deafened than normal mantises, and that mantises which can hear bats' calls will take evasive action. I found that tagged Miomantis cf. natalica Beier flew substantially on dark nights; indoors, undeafened mantises were better at avoiding Rhinolophus clivosus (Rhinolophidae: Microchiroptera) than were deafened mantises (n = 20 pairs; Mann–Whitney test, z = 4.58, p < 0.001). Rhinolophus clivosus echolocates at 80–85 kHz, implying that M. cf. natalica can hear higher frequencies than most mantises (the usual best frequencies for mantises are 30–60 kHz); this is supported by D.D. Yager, who found that two other Miomantis species can hear at 80–150 kHz. The development of higher frequency hearing in Miomantis spp. was probably driven by predation from rhinolophid and hipposiderid bats, many of which echolocate at frequencies over 60 kHz. These taxa would be suitable for further research into predator–prey coevolution.
Roost-site selection and roosting ecology of forest-dwelling bats in southern British Columbia
Authors: Vonhof Maarten J. , Barclay Robert M. R.
Published: May 2008

We used radiotelemetry to examine the roost-site preferences of four species of tree-roosting bats (Eptesicus fuscus, Lasionycteris noctivagans, Myotis evotis, and M. volans) in southern British Columbia, Canada, by radio-tracking bats to their day roosts. We found a total of 21 roost trees: 14 roosts were beneath loose bark, 5 were in cavities excavated by woodpeckers, and 2 were in natural cavities. Entrance height increased with tree height, but roost entrances tended to be situated below the level of the canopy. Of the 22 tree and site variables examined, only 3 significantly discriminated between roost trees and available trees: tree height, distance to the nearest available tree, and percent canopy closure. Bats preferred tall trees associated with low percent canopy closure and a short distance to the nearest available tree. Bats roosted in western white pine, and to a lesser extent ponderosa pine and western larch, in intermediate stages of decay more often than would be expected at random. Bats switched roosts frequently. The distance between subsequent roost trees was short, suggesting a degree of fidelity to a particular group of trees or area of forest. The number of days of rain during the roosting period significantly influenced the number of days spent in a particular roost, and thus ambient conditions may restrict the frequency with which bats can switch roosts.
Female-biased mortality induced by male sexual harassment in a feral sheep population
Authors: Réale Denis , Boussès Patrick , Chapuis Jean-Louis
Published: May 2008

In contrast to most populations of sexually dimorphic ungulates, a 3-year study revealed a tertiary sex ratio (the number of males per female at sexual maturity) strongly biased towards males in the Île Longue feral sheep (Ovis aries) population (Kerguelen subantarctic archipelago). This population presents a main winter lambing season and a secondary summer lambing period. The sex ratios of lambs and lamb carcasses were even. The skewed sex ratio of adults was therefore attributed to shorter longevity of females. We showed that (i) male monthly mortality followed a bimodal distribution with peaks corresponding to the two rutting periods. Male mortality was, however, highest during the winter even though less rutting occurred in this season than in the summer, suggesting that harsher winter conditions enhance the cost of mating competition; (ii) female mortality was related to the rutting activity of males but not to lambing. Female mortality peaked in the summer despite plentiful food resources. This period corresponds to the main rutting peak, suggesting a high survival cost of mating for females. Female mortality due to male harassment was confirmed by direct observations and examination of females injured during rutting periods. This situation may be due to a strongly male-biased operational sex ratio in the population, associated with an inability of males to establish a stable dominance hierarchy within a large flock.
Can dispersal barriers really be used to depict emigrating small mammals?
Authors: Wolff Jerry O. , Schauber Eric M. , Edge W. Daniel
Published: May 2008

Small-mammal enclosure studies have attempted to depict emigrants as animals that are captured after they cross a barrier strip. These "emigrants" are often categorized by age, sex, and reproductive condition. In a similar study with gray-tailed voles (Microtus canicaudus), we captured 307 of 1469 (21%) marked animals across a 1-m barrier strip. These animals consisted disproportionately of males and subadults, but did not differ in longevity or reproductive condition from animals that did not cross the barrier. Forty-two of 45 animals that were captured ≥ 7 times with ≥ 2 captures across the barrier strip had home ranges adjacent to the barrier. These data suggest that most animals caught across the barrier were not emigrating but were making exploratory movements or had home ranges on the edge of the habitat. We question the use of dispersal barriers in depicting emigrants and recommend caution in interpreting results from previous studies involving dispersal barriers.
Size- and age-related variation in the seasonal timing of nesting activity, nest characteristics, and female choice of parental male pumpkinseed sunfish (Lepomis gibbosus)
Authors: Danylchuk Andy J. , Fox Michael G.
Published: May 2008

Parental males from a population of pumpkinseed sunfish (Lepomis gibbosus) were captured throughout the spawning season to examine age- and size-related seasonal trends in nesting activity. Females of spawning pairs were also captured to determine if male body size or nest characteristics influenced their selection of a mate. Large/old (≥ 80 mm; age 4–6 years) parental males commenced nesting earlier in the spring–summer spawning season than small/young (< 80 mm; age 2 and 3 years) parental males. As the spawning season progressed, the proportion of large/old males in the nesting population decreased until more than 70% of the males nesting late in the season were small/young individuals. Small individuals nesting late in the season were inferior in body condition to those that nested earlier in the season. These findings support the hypothesis that size-related differences in energy reserves and metabolism in centrarchids result in size-dependent variation in the timing of nesting activity. The length of females captured spawning at a nest site was not significantly correlated with the length of the parental male, water depth, or distance from shore; however, females captured spawning in firm (sand and gravel) substrates were significantly larger than those spawning in soft (silt or woody debris) substrates. Although all observed nests in the various substrates contained eggs, the positive relationship between body size and fecundity in female pumpkinseeds suggests that a selective advantage for males nesting in firm substrate may accrue through the attraction of larger females.
Movement and spatial use patterns of California sea otters
Authors: Ralls Katherine , Eagle Thomas C. , Siniff Donald B.
Published: May 2008

Movement patterns of sea otters (Enhydra lutris) were followed by daily monitoring of 40 individuals with implanted radio transmitters. Otters of all age and sex classes were most often found within 1–2 km of their locations on the previous day. However, individuals often remained within a small area for an extended period and then suddenly moved a much greater distance within a short time period. There were significant differences among age–sex classes, but not months, in the mean monthly distances between successive daily locations and between extreme locations of individual otters. There were significant differences among both age–sex classes and months in the harmonic mean distance deviation. For all three measures, juvenile males tended to move the greatest distances. Adult males tended to be more sedentary than adult females over the short term, but traveled over greater distances in the long term. Individuals within age–sex classes had different movement patterns, and individuals often had different movement patterns during the same month in successive years. Estimates of the area used by individual otters during a single 24-h period (6.9–1166.4 ha) overlapped previous estimates of home-range size based on much longer time periods.
Breeding-site infidelity in greater snow geese: a consequence of constraints on laying date?
Authors: Lepage Denis , Gauthier Gilles , Reed Austin
Published: May 2008

We studied annual variation in the distribution of greater snow goose (Chen caerulescens atlantica) nests and colonies at a High Arctic breeding site (Bylot Island, Northwest Territories, Canada) from 1988 to 1994. Annual distribution and size of colonies within the study area were highly variable. The distance between colony centres in successive years ranged from 2.9 to 6.9 km [Formula: see text], with no overlap of the areas occupied. Timing of snowmelt and nest-site availability were also very variable. In some years, the area was snow-free at the time the geese arrived, whereas in others, snow persisted for up to 3 weeks after their arrival. However, even in the 3 years of earliest snowmelt (1988, 1993, and 1994), geese used markedly different nesting areas, in both lowland and upland areas. Geese nested in association with snowy owls (Nyctea scandiaca) in the 2 years that owls nested and their nesting success was markedly improved, probably because of the deterrent effect of owls on arctic foxes (Alopex lagopus), the main nest predator. This suggests that protection from nest predators is an important determinant of nest-site selection. The lack of fidelity to a specific nesting location is unusual in geese. We suggest that large annual variability in timing of snowmelt, predation pressure, and availability of feeding areas during the prenesting period, combined with the need to lay at an optimal date because of the short arctic nesting season, probably explain the low nest-site fidelity in this population.
Flexible effort in breeding seabirds: adjustment of provisioning according to nestling age and mass
Authors: Bertram Douglas F. , Welham Clive V. J. , Ydenberg Ronald C.
Published: May 2008

We examined whether rhinoceros auklet (Cerorhinca monocarata) parents are able to adjust their provisioning effort in response to chick demand. A fostering experiment in which nestlings of different ages and masses were exchanged between burrows was employed to examine parental provisioning effort before and after the exchange. Daily mass increments of the nestlings were used to estimate the amount fed on the previous night, using a model based on data from captive chicks raised on a controlled diet. Our results demonstrate that rhinoceros auklet parents somehow assess and respond to the needs of their chicks by delivering more to older and larger fostered chicks and less to younger and smaller fostered chicks. Our results confirm and extend a growing body of information which shows that seabird parents can adjust provisioning effort when feeding young. We highlight how studies to date have differentially manipulated nestling age and hunger, thus complicating a comparative approach. Testing for interspecific differences in parental ability to respond to chick demands will require studies that employ comparable types of manipulations for a variety of seabird species.
Adaptive significance of growth patterns in juvenile spotted owls
Authors: Kristan Deborah M. , Gutiérrez R. J. , Franklin Alan B.
Published: May 2008

We examined relative growth patterns of six morphological features of fledgling spotted owls (Strix occidentalis). Juvenile spotted owls exhibit early nest desertion, possibly to avoid parasitism or detection by predators or to reduce thermal stress. Because juveniles leave the nest before they are capable fliers, they primarily use morphological features other than their wings and tail to move among roost locations. When juveniles fledged, mass, wing chord, and tail length were still increasing, whereas tarsus length and bill depth were near adult size. Moreover, juvenile bill length was greater than mean adult bill length for nearly all time periods. Early growth in tarsi and bills may increase juveniles' ability to effectively locomote after they have fledged but before they can adequately fly.
Why lemmings have indoor plumbing in summer
Authors: Boonstra Rudy , Krebs Charles J. , Kenney Alice
Published: May 2008

The faeces and urine of microtine rodents are visible in ultraviolet light, and diurnal raptors, such as European kestrels (Falco tinnunculus) and rough-legged buzzards (Buteo lagopus), have the ability to see in ultraviolet light. It has been reported that in Fennoscandia, these raptors use this ability to concentrate their hunting activity in spring on areas where microtines are abundant. We hypothesized that in arctic tundra areas in summer, intense avian predation pressure and short vegetation should select for microtine behaviour that would minimize their exposure to these raptors. We dug up 62 collared lemming (Dicrostonyx groenlandicus) burrows in the Canadian Arctic and all had underground latrines. Latrines are not hidden underground in winter, when lemmings live under the snow, build nests above ground, and defecate above ground, nor does this occur in microtine species living in temperate areas, where summer vegetation growth is greater. Thus, high predation risk may influence not only where prey forage but also where they defecate.
Can echolocation calls provide information about group identity in the little brown bat (Myotis lucifugus)?
Authors: Pearl D. L. , Fenton M. B.
Published: May 2008

We studied the potential for colony-specific echolocation calls at maternity colonies of little brown bats, Myotis lucifugus, in Chautauqua County, New York. By analyzing echolocation calls recorded from free-flying bats returning to their roosts before dawn and those of known individuals in a captive setting, we tested for structural differences in the echolocation calls among maternity colonies. There were significant differences in the structure of the echolocation calls among the maternity colonies in both data sets, but the nature of these differences may depend on the setting in which the echolocation calls were produced. The echolocation calls of volant juveniles differed from those of adult females. Colony-specific echolocation calls could facilitate group and site recognition in microchiropteran bats.
Nonmetric morphometry of the skull of the harbour porpoise,Phocoena phocoena, in the western North Atlantic and eastern North Pacific
Authors: Gao Anli , Gaskin D. E.
Published: May 2008

A total of 456 skulls of harbour porpoises, Phocoena phocoena, from North American institutions were coded for 40 nonmetric characters. Codes for morphs were arrayed in relative rankings, reflecting trends of variation. Chi-squared contingency test, Kruskal – Wallis one-way analysis of variance, stepwise discriminant analysis (Wilks' method), and jackknife methods were employed in the analyses. The nonmetric cranial characters were not found to be an efficient method to define geographical populations of harbour porpoises. Although differences could be detected by χ2analysis, no really significant segregation has developed in nonmetric cranial traits between putative subpopulations of harbour porpoises in the western North Atlantic and eastern North Pacific despite the geographical and reproductive isolation of these continental populations. It might result from the species' shorter history compared with that of the common dolphin, Delphinus delphis.
Marten selection of postfire seres in the Alaskan taiga
Authors: Paragi Thomas F. , Johnson W. N. , Katnik Donald D. , Magoun Audrey J.
Published: May 2008

During 1991 – 1994 we tested whether martens (Martes americana) selectively used postfire seres in the Alaskan taiga and whether selection could be explained by differences in marten hunting behaviour, habitat, prey abundance, or demography. Forest seral stages included early-successional tall shrub – sapling (1985 burn), midsuccessional dense tree (1966 burn), and mature coniferous (100–115 years old). Most studies of marten – habitat relationships from lower latitudes suggest that martens require coniferous forest and avoid open areas. We found that martens did not select forest cover types or burn features at the stand scale (within the home range). However, marten abundance was greatest in the 1985 burn, which had the lowest canopy cover but the highest coarse woody debris density, autumn arvicoline biomass, and winter hunting intensity (index to foraging suitability). Martens in the 1985 burn were predominantly juvenile, with few adult (≥2 years old) females present. We hypothesize that our study area of predominantly early – midsuccessional forest was a "sink" for immature and transient martens dispersing from surrounding mature forest. If our hypothesis is correct and applies elsewhere in the taiga, then fur trapping for martens in recent burns could be a productive yet conservative harvest strategy. Future research should focus on habitat requirements of parturient females.
Breeding dispersions and site fidelity of American redstarts (Setophaga ruticilla)
Authors: Lemon R. E. , Perreault S. , Lozano G. A.
Published: May 2008

We relate features of the breeding dispersions and site fidelity of American redstarts (Setophaga ruticilla) to breeding success and interpret the findings in terms of sexual selection. One-year-old male redstarts show delayed plumage maturation, making male dispersions particularly easy to appreciate. In our study site in New Brunswick, Canada, older males usually arrived early each breeding season and gathered in contiguous territories or neighborhoods, while subadult males arrived later and settled peripherally to the adults. Subadult males constituted about 40% of the male population, on average, yet only 5% of banded nestlings returned to the natal breeding ground. Also, newly adult males, 2 years old or more, constituted about 15% of all males. Nearly 50% of adult males returned, twice the return rate of subadults. Among returns, older males returned more often to the same territory than did those that were subadult the previous year. Regardless of age, returns of males in a subsequent year were predicted more by the duration of their stay on the breeding territory than reproductive success. Males outnumbered females. Females returned less often than their mates, but more often if they had fledged young. Females rarely returned to the same mate or territory, but often returned to the same vicinity. The subadult males seem to represent a special dispersive phase of the life history. The evidence indicates strong competition among males for territories and females, older males being more often successful in both circumstances.
INDIUM NITRIDE: A NEW MATERIAL FOR HIGH EFFICIENCY, COMPACT, 1550nm LASER-BASED TERAHERTZ SOURCES IN CHEMICAL AND BIOLOGICAL DETECTION
Authors: WRABACK MICHAEL , CHERN GRACE D. , READINGER ERIC D. , SHEN PAUL H. , KOBLMÜLLER GREGOR , GALLINAT CHAD , SPECK JAMES S.
Published: May 2008

Indium nitride ( InN ) is identified as a promising terahertz (THz) emitter based on the optical and electronic properties of high quality In - and N -face samples. Time domain THz spectroscopy has been employed to measure the pump wavelength and background carrier concentration dependence of THz emission from InN . There is no discernable difference between the In - and N -face InN samples, as expected for the improved crystalline quality and concomitant low background electron density and high mobility for both polarities. While there is only a weak dependence of THz signal on pump wavelength from 800 nm to 1500 nm, there is a strong dependence on background electron density. Modeling shows that the dominant mechanism for THz generation in bulk InN is the current associated with the diffusion of the photo-generated electrons at elevated electron temperature (photo-Dember effect) and the redistribution of the background electrons under drift, with larger screening from the higher mobility electrons as compared to holes. Compensation or p -type doping in conjunction with manipulation of the large internal electric fields in InN/InGaN nanostructures should lead to significant improvements in THz emitters.
THE PHENOMENOLOGY OF HIGH EXPLOSIVE FIREBALLS FROM FIELDED SPECTROSCOPIC AND IMAGING SENSORS FOR EVENT CLASSIFICATION
Authors: GROSS KEVIN C. , PERRAM GLEN P.
Published: May 2008

Conventional munitions emit intense radiation upon detonation which spans much of the electromagnetic spectrum. The phenomenology of time-resolved visible, near- and mid-IR spectra from these fast transient events is poorly understood. The observed spectrum is driven by many factors including the type, size and age of the chemical explosive, method of detonation, interaction with the environment, and the casing used to enclose the explosive. Midwave infrared emissions (1800–6000 cm -1, 1.67–5.56 μm) from a variety of conventional military munitions were collected with a Fourier transform spectrometer (16 cm-1, 21 Hz) to assess the possibility of event classification via remotely sensed spectra. Conventional munitions fireballs appear to be graybodies in the midwave. Modeling the spectra as a single-temperature Planckian (appropriately modified by atmospheric transmittance) provided key features for classification and substantially reduced the dimensionality of the data. The temperature cools from ~1800 K to ambient conditions in 3–5 s, often following an exponential decay with a rate near 1 s-1 second. A systematic, large residual spanning 2050–2250 cm -1 was consistently observed shortly after detonation and may be attributable to hot CO 2 emission at the periphery of the fireball. For two different explosive types detonated under similar conditions, features based on the temperature, area and fit residuals could be used to distinguish between them. This paper will present the phenomenology of detonation fireballs and explore the utility of physics-based features for explosive classification.
MULTIDIMENSIONAL IDENTIFICATION OF CHEMICAL WARFARE AGENTS USING SHAPED FEMTOSECOND PULSES
Authors: PASTIRK IGOR , DANTUS MARCOS
Published: May 2008

Detection and identification of chemical warfare simulants based on multidimensional phase shaped femtosecond laser pulses coupled to mass spectrometry (MS) is demonstrated. The presented approach is based on binary phase shaping (BPS) and aims to improve the accuracy and precision required for security applications. It is based on multiphoton intrapulse interference of femtosecond laser pulses. Spectra retrieved by applying n-differently shaped pulses represent n-dimensions of the analysis. We present a multidimensional technique for detection and identification of analogues to chemical agents and mixtures in real-time. Experimental results for dimethyl phosphate, pyridine, and three isomers of nitrotoluene are presented.
LASER-IONIZATION MASS SPECTROMETRY OF EXPLOSIVES AND CHEMICAL WARFARE SIMULANTS
Authors: HUESTIS DAVID L. , MULLEN CHRISTOPHER , COGGIOLA MICHAEL J. , OSER HARALD
Published: May 2008

The objective of the present study was to better understand the photophysics of explosives and chemical warfare simulants in order to develop better performing analytical tools. Photoionization mass spectra were taken using three optical schemes. The first was resonance-enhanced multiphoton ionization (REMPI) using few-ns duration 248 or 266 nm laser pulses. The second scheme was non-resonant multiphoton ionization (MPI) using 100 fs duration laser pulses at wavelengths between 325 and 795. The third approach was single photon ionization (SPI) using few-ns duration 118 nm laser pulses. For all the molecules investigated, mass spectra resulting exposure to ns-duration 248 or 266 nm laser pulses consisted of only low molecular weight fragments. Using fs-duration laser pulses produced more complicated, potentially analyzable, fragmentation patterns, usually with some parent peak. Single photon ionization gave the best results, with mass spectra consisting of almost only parent peak, except for the case of TATP.
PREDICTING THE PATH OF ELECTRONIC TRANSPORT THROUGH A MOLECULAR DEVICE VIA A MOUNTAIN-PASS ALGORITHM
Authors: RECINE GREG , WOOLARD DWIGHT L.
Published: May 2008

The so-called “mountain-pass” theorem allows for the finding of a critical point on the path between two points on a multidimensional contour where the maximal elevation is minimal. By implementing the “elastic string algorithm”, it is possible to not only find the critical point, but to compute the mountain-pass itself on a finite-dimensional contour. For a given molecule that sits between two probes making up a nanostructure device, we propose that the mountain-pass will be a likely path of electron transport through the molecule, the contour being the electronic potential of the molecule. This potential along this path will be used as the input potential for SETraNS, a 1D Wigner-Poisson electron transport solver in order to explore the current-bias characteristics of such the molecule in such a device. In order to calculate the mountain pass, the elastic string algorithm is used to set up a constrained non-linear optimization problem which is, in turn, solved via a Monte Carlo method. We will compute the mountain-pass for a well-known test contour in order to show the validity of this approach. The procedure developed here is to be combined with conformational analysis via the molecular modeling program AMBER and the quantum transport program SETraNS in order to predict molecular function. When achieved, this combined procedure will allow for the better design and implementation of nanoscale molecular devices for application such as sensing, switching and data processing.
THEORY OF GRAVITATION THEORIES: A NO-PROGRESS REPORT
Authors: SOTIRIOU THOMAS P. , LIBERATI STEFANO , FARAONI VALERIO
Published: May 2008

Already in the 1970s there where attempts to present a set of ground rules, sometimes referred to as a theory of gravitation theories, which theories of gravity should satisfy in order to be considered viable in principle and, therefore, interesting enough to deserve further investigation. From this perspective, an alternative title of this paper could be "Why Are We Still Unable to Write a Guide on How to Propose Viable Alternatives to General Relativity?". Attempting to answer this question, it is argued here that earlier efforts to turn qualitative statements, such as the Einstein equivalence principle, into quantitative ones, such as the metric postulates, stand on rather shaky ground — probably contrary to popular belief — as they appear to depend strongly on particular representations of the theory. This includes ambiguities in the identification of matter and gravitational fields, dependence of frequently used definitions (such as those of the stress–energy tensor or classical vacuum) on the choice of variables, etc. Various examples are discussed and possible approaches to this problem are pointed out. In the course of this study, several common misconceptions related to the various forms of the equivalence principle, the use of conformal frames and equivalence between theories are clarified.
UNSPEAKABLES AND THE EPISTEMOLOGICAL PATH TOWARD QUANTUM GRAVITY
Authors: SUDARSKY DANIEL
Published: May 2008

We offer a critical assessment of some generic features of various current approaches to the construction of a theory of quantum gravity. We argue that there is a need for further conceptual clarifications before such an enterprise can be launched in a truly well-grounded setting, and that one of the guiding principles that can be viewed as part of the reasons for successes of the past theoretical developments is the identification of unspeakables — concepts that should not only play no role in the formulation of the theories, but ones that the formalism of the theory itself should prevent from ever being spoken about.
QUANTUM STRUCTURE OF GEOMETRY: LOOPY AND FUZZY?
Authors: CORICHI ALEJANDRO , ZAPATA JOSÉ A.
Published: May 2008

In any attempt to build a quantum theory of gravity, a central issue is to unravel the structure of space–time at the smallest scale. Of particular relevance is the possible definition of physical coordinate functions within the theory and the study of their algebraic properties, such as noncommutativity. Here we approach this issue from the perspective of loop quantum gravity and the picture of quantum geometry that the formalism offers. In particular, as we argue here, this emerging picture has two main elements: (i) the nature of the quantum geometry at the Planck scale is one-dimensional, and polymeric with quantized geometrical quantities; and (ii) appropriately defined operators corresponding to coordinates by means of intrinsic, relational constructions become noncommuting. This particular feature of the operators, which operationally localize points on space, gives rise to an emerging geometry that is also, in a precise sense, fuzzy.
ESTIMATE OF THE SHAKURA–SUNYAEV VISCOSITY PARAMETER IN THE KEPLERIAN ACCRETION DISK FROM HYDRODYNAMIC TURBULENCE
Authors: MUKHOPADHYAY BANIBRATA
Published: May 2008

Recently, in a series of papers, Mukhopadhyay and his collaborators have argued for possible pure hydrodynamic turbulence in a Keplerian accretion disk. This is essentially important to solving the puzzle of the transport mechanism in cold accretion disk systems where the temperature could be lower than 5000 K, where magnetorotational instability seems not to be working to trigger turbulence. Here we quantify the corresponding instability and turbulence in terms of turbulent viscosity and obtain the famous Shakura–Shunyaev viscosity parameter, α. It is exciting that the range of α obtained from our analysis is 0.1 ≳ α ≳ 0.0001 for a realistic parameter region. This range also suggests that once the hydrodynamic instability described by Mukhopadhyay and his collaborators leads to turbulence — an effect which should exist in systems independent of being hot or cold — the effect may compete with the magnetohydrodynamic effect even in hot accretion disks and thus may be effective in transporting matter in hot gas systems as well.
ORIGIN OF MATTER OUT OF PURE CURVATURE
Authors: DADHICH NARESH , MAEDA HIDEKI
Published: May 2008

We propose a mechanism for the origin of matter in the universe in the framework of Einstein–Gauss–Bonnet gravity in higher dimensions. The new static black hole solution recently discovered by the authors,1 with the Kaluza–Klein split of space–time as a product of the usual [Formula: see text] with a space of negative constant curvature, is indeed a pure gravitational creation of a black hole which is also endowed with a Maxwell-like gravitational charge in four-dimensional vacuum space–time. This solution has been further generalized to include radially flowing radiation, which means that extra-dimensional curvature also produces matter distribution asymptotically, resembling charged null dust. The static black hole could thus be envisioned as being formed from anti–de Sitter space–time by the collapse of radially inflowing charged null dust. It thus establishes the remarkable reciprocity between matter and gravity — as matter produces gravity (curvature), gravity produces matter. After the Kaluza–Klein generation of the Maxwell field, this is the first instance of realization of matter without matter in the classical framework.
BLACK HOLES HAVE A GOOD TEMPER(ATURE)
Authors: HOD SHAHAR
Published: May 2008

It is well known that black holes are the most extreme objects in nature: they have the maximal energy and entropy capacities allowed by the laws of physics. In this essay we reveal another extreme property of these fascinating objects: black holes have the fastest relaxation dynamics allowed by a quantum theory of gravity. From information theory and thermodynamic considerations a universal bound on the relaxation time τ of a perturbed physical system is inferred, τ ≥ ħ/πT, where T is the system's temperature. We then show that black holes may actually attain this fundamental bound, which makes them the fastest-relaxing objects in the universe.
QUIESCENT COSMOLOGY AND THE FINAL STATE OF THE UNIVERSE
Authors: HÖHN PHILIPP A. , SCOTT SUSAN M.
Published: May 2008

It has long been a primary objective of cosmology to understand the apparent isotropy in our universe and to provide a mathematical formulation for its evolution. A promising school of thought for its explanation is quiescent cosmology, which already possesses a mathematical framework, namely the definition of an isotropic singularity, but only for the initial state of the universe. A complementary framework is necessary in order to also describe possible final states of the universe. Our new definitions of an anisotropic future endless universe and an anisotropic future singularity, whose structure and properties differ significantly from those of the isotropic singularity, offer a promising realization for this framework. The combination of the three definitions together may then provides the first complete formalization of the quiescent cosmology concept.
MODELING ENDOGENOUS RULE CHANGES IN AN INSTITUTIONAL CONTEXT: THE ADICO SEQUENCE
Authors: SMAJGL ALEX , IZQUIERDO LUIS R. , HUIGEN MARCO
Published: May 2008

Agent-based modeling is being increasingly used to simulate socio-techno-ecosystems that involve social dynamics. Humans face constraints that they sometimes wish to challenge, and when they do so, they often trigger changes at the scale of the social group too. Including such adaptation dynamics explicitly in our models would allow simulation of the endogenous emergence of rule changes. This paper discusses such an approach in an institutional framework and develops a sequence that allows modeling of endogenous rule changes. Parts of this sequence are implemented in a NetLogo KISS model to provide some illustrative results.