bluuebunny/crossref_metadata_2025 huggingface dataset:
Infestations expérimentales de crabes juvéniles par la sacculine. Ultrastructure des racines parasitaires en croissance et relations avec la niasse ganglionnaire ventrale de l'hôte
Authors: Payen Geneviève G. , Hubert Michelle , Turquier Yves , Rubiliani Claudio , Chassard-Bouchaud Colette
Published: April 2009

Experimental infestations of young Carcinus with Sacculina carcini indicate that the ventral ganglionic mass (VGM) is the first "target" of the parasite roots into the host tissues. As in pubescent crabs naturally parasitized, either with or without an external visceral sac, the roots penetrate and invade that area of the central nervous system during the first month of infestation.Ultrastructural study of the developing roots, in contact with the VGM, leads to the conclusion that apart from a few embryonic characters, the root cells show a cytostructure similar to the one that has been observed in the roots naturally parasitizing pubescent crabs, whether the external visceral sac is present or not.In the two cases of infestation the roots which cross the neurolemma bring about a marked disorganization of ganglia in consequence of the alteration of the neuroglia, neuropiles and neurosecretory areas.An action of the parasite at a distance, i.e. in the absence of contact of the roots with the ganglia, also occurs. It is especially marked as early as 1 month after infestation by a degeneration of the secretory perikarya.A thin sheath of connective tissue is sometimes visible between the growing roots and the VGM of juvenile crabs. However, the existence of that tissue cannot be definitely attributed to a host defense reaction.No effect of the developing parasite on the already differentiated external sex characters of the host has been noticed within the limits of the experiments.
The feeding ecology of the larvae of the shore fly Scatella picea (Walker) (Diptera: Ephydridae)
Authors: Connell Terry D. , Scheiring Joseph F.
Published: April 2009

Larvae of the shore fly, Scatella picea (Walker) (Diptera: Ephydridae), were tested on 14 species of algae to determine the suitability of the algae as food. Survivability depended upon the ability of the larval flies to reach the adult stage. The degree of suitability of the algae varied greatly across algal taxa. R. S. Zack and B. A. Foote researched the trophic ecology of S. stagnalis (Fallén), an ephydrid species that commonly coexists with S. picea. In comparing the two flies, it was found that S. stagnalis could utilize blue–green algae as food, while this class of algae was virtually useless to S. picea. It is possible that this difference in utilization efficiency is a factor in resource partitioning between the two species of ephydrids. This difference also can be applied to the problem of taxonomy present in the genus Scatella.
The use of lateral-body bar markings in identification of young-of-year sunfish (Lepomis) in Lake Opinicon, Ontario
Authors: Brown J. A. , Colgan P. W.
Published: April 2009

Lateral-body bar marking differences can be used for identifying young-of-year bluegills and pumpkinseeds. The young-of-year of both species were reared in the laboratory from eggs and examined weekly for lateral-body bar pigmentation development. Pumpkinseeds were found to develop spots between the bars when they had reached the size of 25 mm while bluegills never developed spots but had distinct body bars by 24 mm. Examination of older fish of both species from three natural populations confirmed these differences as species typical.
Ectoparasites and other arthropod associates on two subspecies of plains pocket gophers: Geomys bursarius illinoensis and Geomys bursarius missouriensis
Authors: Spicka Edwin J.
Published: April 2009

Between 4 February and 28 June 1973, 45 plains pocket gophers, Geomys bursarius illinoensis (24) and G. b. missouriensis (21), were examined for ectoparasites. A total of 45 273 arthropods (Acari unless designated otherwise) was collected from G. b. illinoensis in Illinois in the following order of decreasing abundance: Geomylichus floridanus, Geomydoecus illinoensis (chewing louse), Androlaelaps geomys, Euschongastia trigenuala, Echinonyssus longichelae, Pergamasus sp., E. geomydis, Oribella sp., Ixodes sculptus, Pygmephorus scalopi, Dendrolaelaps sp., Pygmephorus sp., Parasitus sp., Ctenophthalmus pseudagyrtes (flea), Cyrtolaelaps sp., Macrocheles sp., Anoetidae, Haemogamasus reidi, Imperipes (I.) spickai, Pygmephorus designants, P. spickai, P. whitakeri, and Scutacarus geomyi. A total of 34 504 arthropods (Acari unless designated otherwise) was collected from G. b. missouriensis in Missouri in the following order of decreasing abundance: Geomydoecus spickai (chewing louse), Geomylichus floridanus, Echinonyssus geomydis, Androlaelaps geomys, Euschongastia trigenuala, Macrocheles sp., Echinonyssus longichelae, Pergamasus sp., Dendrolaelaps sp., Pygmephorus sp., Oribella sp., Saproglyphidae, Pygmephorus scalopi, P. whitakeri, Anoetidae, Cyrtolaelaps sp., Parasitus sp., and Scutacarus missouriensis.
Muscle metabolism of freshwater fish, Tilapia mossambica (Peters), during acute exposure and acclimation to sublethal acidic water
Authors: Murthy V. Krishna , Reddanna P. , Bhaskar M. , Govindappa S.
Published: April 2009

Freshwater fish, Tilapia mossambica (Peters), were subjected to acute exposure and acclimation to sublethal acid water (pH 4.0), and the muscle metabolism was investigated. Differential patterns of carbohydrate metabolism were witnessed in the red and white muscles in response to both acute exposure and acclimation. The glycogen content of red muscle was elevated whereas that of white muscle was depleted on acute exposure. But on acclimation, both the muscles had elevated glycogen content. The red muscle seems to mobilize carbohydrates into both hexose mono- and di-phosphate pathways, but white muscle does so only into the hexose monophosphate pathway on acclimation. In general, both the muscles exhibited suppressed glycolysis and elevated oxidative phase leading to elevated glycogen level. The muscle metabolism was oriented towards conservation of carbohydrates and lesser production of organic acids on acclimation, as a possible metabolic adaptive mechanism of the fish, enabling them to counteract the imposed acid stress.
Comparison of body weights between captive and free-ranging juvenile Richardson's ground squirrels (Spermophilus richardsoni)
Authors: Harding Deborah H. , Rauch Josefine C.
Published: April 2009

Body weights of free-ranging and captive juvenile Richardson's ground squirrels (Spermophilus richardsoni) were determined at regular intervals during the nonhibernating season. Animals in captivity gained weight at a faster rate and to a greater extent than those in their natural habitat. Attainment of maximum weights in captive ground squirrels was associated with a reduction in food intake and could not be related to food availability, a change in temperature, or in photoperiod.
Olfactory response to beetle-produced volatiles and host-food attractants by Oryzaephilus surinamensis and O. mercator
Authors: Pierce A. M. , Borden J. H. , Oehlschlager A. C.
Published: April 2009

A two-choice, pitfall olfactometer which utilizes a petri plate with suspended glass vials was employed to test the response of Oryzaephilus surinamensis (L.) and O. mercator (Fauvel) to various volatile stimuli. Male and female beetles of both species were attracted to pentane extracts of Porapak Q trapped volatiles from beetles, frass, rolled oats, and brewer's yeast over a wide range of stimulus concentrations. For both species, male and female frass contained attractive volatiles in addition to those from unused growth medium. This result and the attractiveness of volatiles from beetles suggest that both sexes produce an aggregation pheromone. Additionally, interspecific attraction to beetle and frass volatiles was demonstrated.
Factors affecting variation in the primary song of North American solitary vireos (Aves: Vireonidae)
Authors: James Ross D.
Published: April 2009

Tape recordings of the primary song of eight subspecies of solitary vireo were examined sonagraphically. Within one population all birds sing a small number of song phrases in common but each bird has a slightly different repertoire of additional phrases. Populations closest together share the most phrases, but even among widely separate groups or subspecies a few of the same phrases may be found. Song learning appears to maintain local uniformity of song while, with drift and recombination, providing opportunities for the development of new song phrases. Only in eastern North America are primary song phrases pure in tone with a gradual shift of frequency-modulated phrases in both grayish and yellowish subspecies in the west. The presence of pure tone phrases in eastern North America probably contributes to and is maintained by the need for species isolation from yellow-throated vireos and does not indicate that eastern and western birds may be separate species. Climate and habitat appear to have little influence on song variability among subspecies.
Growth of Metorchis conjunctus (Cobbold, 1860) Looss, 1899 (Trematoda: Opisthorchiidae) in the bile ducts of various definitive hosts
Authors: Watson Thomas G.
Published: April 2009

Allometric growth of Metorchis conjunctus collected from experimentally infected Felis catus, Sigmondon hispidus, and Canis familiaris was studied. Although subtle variations in allometric exponents were detected for specific organs, similar trends were noted. A general posterior–anterior growth gradient was detected.Significant morphometric and morphological differences between M. conjunctus collected from cats and cotton rats on day 6 postinoculation were not observed on day 10. The presence of vitelline glands and of ova in the uterus indicated that M. conjunctus matured earlier in cotton rats. These results further document an earlier prepatent period of M. conjunctus in cotton rats (12–14 days) than in cats (16–22 days).
Food habits and dietary overlap of perlid stoneflies (Plecoptera) in a tributary of Lake Ontario
Authors: Johnson James H.
Published: April 2009

Food habit studies were conducted on the nymphs of three species of sympatric perlid stoneflies from May to September 1979 in Orwell Brook, New York. A total of 1106 specimens were examined, which included 744 Phasganophora capitata, 251 Paragnetina immarginata, and 111 Acroneuria abnormis. Chironomids, trichopterans, and ephemeropterans were generally the principal, prey of all three species. Using Horn's measure of overlap, the monthly diets of P. immarginata and P. capitata were most similar [Formula: see text] and the diets of A. abnormis and P. immarginata[Formula: see text] least similar. Diel trends in food consumption during July indicated that the feeding intensity of both P. immarginata and P. capitata was the greatest from 2100 to 0500 hours. Examination of the guts of P. immarginata and P. capitata at 4-h intervals over a 24-h period showed that there was considerable variation in the diel diet composition of these species.
Three new genera of zerconid mites (Acari, Gamasida: Zerconidae) from the United States of America
Authors: Błaszak C.
Published: April 2009

Three new monotypic genera in the family Zerconidae (Acari: Gamasida) from the United States are described: Krantzas gen.nov. (type species K. mirificus sp.nov.), Lindquistas gen.nov. (type species. L. amyihetes sp.nov.), and Hypozercon gen.nov. (type species. H. macleani sp.nov.). Krantzas is related to genera characterized by absence both of adgenital shields and a single opening of glands gv2, and is also related to genera characterized by peritremal shields terminating truncately behind the fourth pair of coxae. In this genus the additional lateroventral shield is situated between the peritremal and ventroanal shields. Lindquistas is related to genera characterized by the peritremal shield terminating truncately behind the fourth pair of coxae and by having two short, smooth peritremal setae. Members of this genus are similar to those of Macrozercon Błaszak and Bledas Halašková. Hypozercon is related to genera characterized by having the peritremal shields extended posteriorly and having two unequal setae on the peritremal shield. Members of this genus are similar to those of Mesozercon Błaszak and Neozercon Petrova.
Growth and development of geographic and crossbred strains of colonized Simulium decorum (Diptera: Simuliidae)
Authors: Brenner R. J. , Cupp E. W. , Bernardo M. J.
Published: April 2009

The developmental times from larval hatch to adult emergence were computed for strains of Simulium decorum from Warm Springs, Georgia (GA), and Dryden Lake, New York (DL). Rearings were conducted at several constant temperatures. Differences between geographic strains and between sexes within strains were significant in nearly every instance (P < 0.01). At cool temperatures (13 to 17 °C), the GA strain developed more quickly; however, this trend was reversed at intermediate temperatures (18 to 20 °C), and at 21 °C only GA males developed faster than DL males. With few exceptions, both sexes of the GA strain required more cumulative degree-days for development than their northern counterparts.The number of instars was determined for each strain by measuring the length of the postgena of head capsules collected during warm (21 °C) and cool (13 °C) rearings. Although both strains pass through seven stadia, differences between strains were noted in the size of middle instars. In all rearings sexual dimorphism was evident in the morphology of last-instar head capsules; in rearings conducted at cool temperatures (13 °C), sexes could also be separated by the size of last-instar head capsules.Strains were crossed and their progeny reared. High values for net reproductive rate (R0), fecundity, and adult survival suggest that heterosis resulted from crossbreeding the two geographic strains.
Use of logged habitats in winter by moose cows with calves in northeastern Ontario
Authors: Thompson Ian D. , Vukelich Milan F.
Published: April 2009

Use of logged areas south of Hearst, Ontario, by moose cows with calves was studied in winter from 1977 to 1979. Cutovers selected averaged 64 ha in early winter and 16 ha in late winter and were most often in lowland areas. Cuts were generally not used until they were at least 18 years old. At least three residual stands of timber were present including one large stand in upland or mesic habitat averaging 42 ha on early winter areas and 107 ha on late winter sites. Basal area of conifers in these stands was 9 m2/ha in early winter sites and 13 m2/ha in late winter sites. Discriminant analysis revealed differences between early winter sites, late winter sites, and locations where the animals were not found based on the size of residual stands, size of cutovers, basal area of small conifers, maximum distance between uncut edges, and average diameter of conifers. Movements between sites were short and substantially reduced as the winter progressed. Moose moved an average of 12 m from cover after the snow reached 65 cm in depth in contrast to in early winter when they usually ranged less than 60 m from cover.
Illusion and reality in comparative physiology
Authors: Ross D. M.
Published: April 2009

The dominant role of comparative physiology (syn. experimental zoology) in the recent history of animal biology is noted. Its objectives, e.g. of contributing to knowledge of phylogenetic relationships and of discovering the origins of physiological functions, are considered to have been largely illusory when the data are examined. It is argued that in reality comparative physiology is concerned only with the description of adaptations, albeit at a sophisticated technical and conceptual level compared with natural history or general morphology. Comparative physiology has not produced any special theory or general explanation for physiological adaptation going beyond Darwin's general theory of natural selection.
Helminth parasites of the muskrat (Ondatra zibethicus (L.)) in Newfoundland
Authors: Rigby Michael D. , Threlfall William
Published: April 2009

One hundred and fourteen muskrats (Ondatra zibethicus (L.)), collected between September 1977 and January 1979 in three areas of insular Newfoundland, were examined for helminths, with 11 species being found (7 Digenea, 2 Cestoda, and 2 Nematoda). Diplostomum mergi was recovered from a mammal for the first time. Distribution along the alimentary tract was examined and all helminths recovered preferred the proximal 60% of the small intestine, except Quinqueserialis quinqueserialis and Trichostrongylus calcaratus, which preferred the caecum. Adult and immature muskrats showed differences in the prevalence and intensity of infection and the adults also had larger concurrent infections. In only one case, namely Hymenolepis evaginata, was a parasite species more prevalent in one sex (the males). Small seasonal differences in prevalence and (or) intensity of infection were noted for some parasites and were related to differences in parasite burden of adult and immature hosts and water temperature. A difference in the occurrence of Digenea between sample areas was related to water pH and hardness.
Movements and habitat use by depredating red-winged blackbirds in Simcoe County, Ontario
Authors: Somers J. D. , Gartshore R. G. , Gilbert F. F. , Brooks R. J.
Published: April 2009

Yearly roost populations, temporal patterns of crop use, the relative importance of age-classes and sex classes in depredation, foraging dispersion, and individual movements of radio-equipped birds were assessed in a 3-year study of blackbird depredation in Simcoe County, Ontario. The population of roosting birds totalled 107 400 in 1977, 89 300 in 1978, and 118 200 in 1979 and appeared to be relatively stable, although the number of blackbirds using different flyways entering the roost varied. Sightings of colour-tagged birds indicated that the birds foraged over a wide area and moved from crop to crop depending on crop maturity. The movement pattern was not dependent on age or sex. Colour-tagged male red-winged blackbirds were sighted more frequently than females in field corn in 1978 but there was no difference in 1979. The earlier maturing of wheat may contribute to the lack of bird activity in standing wheat crops. Radiotelemetry studies indicated that there may be a considerable turnover of individuals foraging in a field over the term of a crop's susceptibility to depredation. Observations of starlings and monitoring of one radio-equipped starling suggested that this species may be a potential corn depredator. The relevance of results to management strategies for depredating red-winged blackbirds is discussed.
Life history adaptations of the fingernail clams Sphaerium occidentale and Musculium securis to ephemeral habitats
Authors: McKee P. M. , Mackie G. L.
Published: April 2009

Life histories of the fingernail clams Sphaerium occidentale and Musculium securis from a temporary pond are examined to show adaptations to ephemeral habitats. Musculium securis ceases growth upon birth and only newborn occur in the dry pond, whereas all length classes of S. occidentale are omnipresent. Aestivation is not obligatory in the life cycle of either species. Both grow and reproduce regardless of aestivation experience.Life history strategies of both clams counteract environmentally imposed, density-independent mortality pressures. Sphaerium occidentale has slower growth and greater longevity than M. securis which must complete its life cycle before the pond dries. During aestivation, broods continue development in S. occidentale but not in M. securis. If water is present in fall, both opportunistically use this period for development. Both produce large numbers of small newborn and exhibit multivoltine and iteroparous strategies, although M. securis releases consecutive broods only during a single spring birth period and only if the aquatic season is extended, whereas S. occidentale releases consecutive broods during a spring birth period, in autumn if water is present, and during a 2nd year. A mixed tactic, according to the stochastic theory, has been adopted by both for survival under highly variable environmental stresses.
Morphometric variation in Clethrionomys gapperi: are all voles created equal?
Authors: Mihok Steve , Fuller William A.
Published: April 2009

A general feature of population cycles in microtine rodents is the Chitty effect: large body size in peak populations. This phenomenon does not occur in a subarctic population of Clethrionomys gapperi that has been studied extensively for 15 years. Voles from various phases of the population cycle differ primarily in terms of complex patterns of "shape" rather than "size." These patterns are strongly correlated with environmental conditions during periods of growth or thermal stress. Increasing populations are nevertheless characterized by changes in the relationships between body size and skull size. Voles larger than predicted on the basis of their skull size are captured in springs characterized by an increase in density from the previous spring. Hence the Chitty effect is present in this population but it is expressed in a different way. Qualitative changes in some weakly cycling microtine populations may therefore be relatively difficult to detect without a better understanding of the mechanisms underlying this morphometric, behavioural, genetic complex.
The adaptive value of polygyny in marsh-nesting red-winged blackbirds; renesting, territory tenacity, and mate fidelity of females
Authors: Picman Jaroslav
Published: April 2009

Some female red-winged blackbird individuals laid as many as four or five clutches in a single breeding season. Renesting attempts followed nesting failures and high renesting rates were characteristic of unsuccessful females. Most renesting female redwings exhibited a strong territory tenacity. However, some females renested in a different territory and I tried to determine why these individuals moved. Since certain birds always moved more between their renesting attempts than others, the female tendency to move is probably intrinsically determined. Extrinsic factors such as the density of nest predators, male age, and harem size did not influence female movements.The strong site tenacity of female redwings has probably been favoured by (1) advantages of familiarity with the habitat, and (2) strong selection on females for mate and harem fidelity which can be achieved most efficiently when males and females return to their original territories. Renesting with the same male and females from the same harem should increase female's reproductive success because cooperation in nest defense is more efficient between familiar birds. The strong tendency of females to renest in the same area in consecutive years significantly influences mating success of males because new males "inherit" harems of previous territory holders.
Profondeur, vase et courant, facteurs de micro-répartition transversale du benthos dans l'estuaire d'eau douce du Saint-Laurent (Québec)
Authors: Vincent B.
Published: April 2009

The distribution of species and the structural variations of the benthic associations have been studied along a transect line in the St. Lawrence River where the physico–chemical parameters of the water are fairly stable. The most abundant species follow a definite zonation but no species is really typical of any one habitat. On the other hand, the structure of the benthic clusters reflects, by order of importance, the depth, the percentage of silt, and the current velocity. The diversity is independent of these factors, whereas the density of the organisms, the number of taxa, and the equitability are all associated with the percentage of silt.[Journal translation]
Influence of temperature, water current, illumination, and time on activity and substrate selection in juvenile smallmouth bass (Micropterus dolomieui)
Authors: MacCrimmon Hugh R. , Robbins William H.
Published: April 2009

Behaviour of wild juvenile smallmouth bass, Micropterus dolomieui, in the laboratory was significantly influenced by water temperature, current, and illumination. Activity increased with increasing water temperature and (or) water current. When exposed to black and white substrate, selection of black was inversely dependent on temperature and current, and highly correlated with fish activity (r = 0.995, P < 0.001, inverse cubic relation). Substrate pattern influenced fish activity, aggregation, and social interaction. Activity levels increased with increasing incident illumination whereas selection of black substrate declined, particularly at higher water temperatures. Older juveniles became less active with age and preferred black substrate when available, thereby indicating a developing behavioural pattern which favours survival and energy conservation under natural nursery conditions by the discrete use of available cover.
Proliferation and renewal of the epithelium in the intestine of young adult anadromous sea lampreys, Petromyzon marinus L.
Authors: Youson John H. , Langille Robert M.
Published: April 2009

The pattern of incorporation of [3H]thymidine in the intestinal epithelium of young adults of the anadromous sea lamprey, Petromyzon marinus L., was examined for up to 41 days using autoradiography. Compared with haemopoietic tissue of the fat column and the epithelium of the kidney, the intestinal epithelium does not rapidly incorporate the isotope. The epithelia of the anterior and posterior intestines and the hindgut regions all undergo a proliferation which, based on changes in the labelling index through time, suggest that a renewal of the epithelium takes place in each region. Most of the cells undergoing cell division are specialized absorptive cells but, in the posterior intestine and hindgut, mucous cells also undergo a variable rate of division. Although there is a slightly greater frequency of labelled cells at the bases of the longitudinal folds, there are no definite zones of proliferation in any region of the intestine. Instead, patches of dividing cells appear throughout the height of longitudinal mucosal folds. This is similar to the situation in parts of the intestine of larval lampreys and the intestine of amphibian tadpoles but unlike the case in other fishes.
Morphometrics of Romanomermis culicivorax Ross and Smith, 1976 (Nematoda: Mermithidae)
Authors: Curran J.
Published: April 2009

Intraspecific variability and the influence of environmental factors on the morphometrics of Romanomermis culicivorax Ross and Smith, 1976 were determined by rearing the progeny of a single mating pair under different parasite intensities, host species, and temperatures. Individual measurements were frequently affected by environment and discriminant analysis revealed differences in overall shape between sibling populations. These effects were not constant within or between sexes. The growth relationships between measurements were examined and because of allometry a number of ratios commonly used in mermithid taxonomy at the species level were rejected. This led to an evaluation of morphometrics in species diagnosis.
Diel activity and diet of three sympatric sticklebacks in tidal salt marsh pools
Authors: Worgan J. P. , FitzGerald G. J.
Published: April 2009

The activity patterns and diet of the adults of three sympatric sticklebacks, Gasterosteus aculeatus, Gasterosteus wheatlandi, and Pungitius pungitius, are compared to learn how three sympatric species share time and food resources. Catch data from unbaited traps indicate that all species are equally diurnal. Females of all species feed almost exclusively in the early morning. No periodicity was observed in the feeding of males compared with females, because males fed infrequently. The diets of the three species were similar though the importance of certain prey items varied with species and sex. Results show that resource partitioning along the dimensions of food type and time are of minor importance in explaining coexistence of the three species during their breeding season.
A comparison of neighbour–stranger discrimination in eastern and western meadowlarks
Authors: Falls J. Bruce , d'Agincourt Lorraine G.
Published: April 2009

Eastern meadowlarks, which have large song repertoires, showed weaker neighbour–stranger (N–S) discrimination than western meadowlarks with smaller repertoires. Discrimination in western meadowlarks was similar to that reported for other species with repertoires of comparable size. Repertoires may interfere with mechanisms responsible for N–S discrimination, resulting in more strife between neighbors than in species with single songs. This may be a trade-off for benefits of repertoires or may be adaptive where neighbors threaten one another. Significant differences in response to N and S songs all occurred between the first two presentations in N–S–N (rather than S–N–S) sequences. Carry-over of the response to the S song may result from poor discrimination or from intolerance toward the N song, once the subject locates it inside his territory.
The tusk of the narwhal (Monodon monoceros L.): interpretation of its function (Mammalia: Cetacea)
Authors: Best Robin C.
Published: April 2009

For over a century, scientists have speculated on the biological function of the tusk of the male narwhal. Proposed functions have included use of the tusk as a weapon, use for opening breathing holes in sea ice, use in feeding, use as an acoustic organ, and function as a secondary sex character. The weight of evidence in this literature review supports a theory that the narwhal tusk serves as a secondary sex character of males, for nonviolent assessment of hierarchical status on the basis of relative tusk size. Relative tusk size is evidently determined in frontal encounters by rival males.
Evidence for differential predation on an estuarine stickleback community
Authors: FitzGerald Gérard J. , Dutil Jean-Denis
Published: April 2009

The diet of the black-crowned night heron (Nycticorax nycticorax) feeding in June and July along the southern shore of the St. Lawrence Estuary was composed primarily of the threespine stickleback Gasterosteus aculeatus. Three other sticklebacks, G. wheatlandi, Pungitius pungitius, and Apeltes quadracus occur in areas where the birds feed but were not eaten. It is suggested that differential predation on G. aculeatus may diminish interspecific competition for nest sites where the four stickleback species co-occur on the breeding grounds.
A Comparative Study of Probabilistic Ranking Models for Chinese Spoken Document Summarization
Authors: Lin Shih-Hsiang , Chen Berlin , Wang Hsin-Min
Published: April 2009

Extractive document summarization automatically selects a number of indicative sentences, passages, or paragraphs from an original document according to a target summarization ratio, and sequences them to form a concise summary. In this article, we present a comparative study of various probabilistic ranking models for spoken document summarization, including supervised classification-based summarizers and unsupervised probabilistic generative summarizers. We also investigate the use of unsupervised summarizers to improve the performance of supervised summarizers when manual labels are not available for training the latter. A novel training data selection approach that leverages the relevance information of spoken sentences to select reliable document-summary pairs derived by the probabilistic generative summarizers is explored for training the classification-based summarizers. Encouraging initial results on Mandarin Chinese broadcast news data are demonstrated.
Two-Stage Hypotheses Generation for Spoken Language Translation
Authors: Chen Boxing , Zhang Min , Aw Ai Ti
Published: April 2009

Spoken Language Translation (SLT) is the research area that focuses on the translation of speech or text between two spoken languages. Phrase-based and syntax-based methods represent the state-of-the-art for statistical machine translation (SMT). The phrase-based method specializes in modeling local reorderings and translations of multiword expressions. The syntax-based method is enhanced by using syntactic knowledge, which can better model long word reorderings, discontinuous phrases, and syntactic structure. In this article, we leverage on the strength of these two methods and propose a strategy based on multiple hypotheses generation in a two-stage framework for spoken language translation. The hypotheses are generated in two stages, namely, decoding and regeneration. In the decoding stage, we apply state-of-the-art, phrase-based, and syntax-based methods to generate basic translation hypotheses. Then in the regeneration stage, much more hypotheses that cannot be captured by the decoding algorithms are produced from the basic hypotheses. We study three regeneration methods: redecoding, n-gram expansion, and confusion network in the second stage. Finally, an additional reranking pass is introduced to select the translation outputs by a linear combination of rescoring models. Experimental results on the Chinese-to-English IWSLT-2006 challenge task of translating the transcription of spontaneous speech show that the proposed mechanism achieves significant improvements over the baseline of about 2.80 BLEU-score.
A polynomial-time approximation scheme for embedding hypergraph in a cycle
Authors: Li Guojun , Deng Xiaotie , Xu Ying
Published: April 2009

We consider the problem of embedding hyperedges of a hypergraph as paths in a cycle such that the maximum congestion, namely the maximum number of paths that use any single edge in a cycle, is minimized.

The
minimum congestion hypergraph embedding in a cycle
problem is known to be NP-hard and its graph version, the
minimum congestion graph embedding in a cycle
, is solvable in polynomial-time. Furthermore, for the graph problem, a polynomial-time approximation scheme for the weighted version is known. For the hypergraph model, several approximation algorithms with a ratio of two have been previously published. A recent paper reduced the approximation ratio to 1.5. We present a polynomial-time approximation scheme in this article, settling the debate regarding whether the problem is polynomial-time approximable.
Linear time 3-approximation for the MAST problem
Authors: Berry Vincent , Paul Christophe , Guillemot Sylvain , Nicolas François
Published: April 2009

Given a set of leaf-labeled trees with identical leaf sets, the well-known Maximum Agreement SubTree (MAST) problem consists in finding a subtree homeomorphically included in all input trees and with the largest number of leaves. MAST and its variant called Maximum Compatible Tree (MCT) are of particular interest in computational biology. This article presents a linear-time approximation algorithm to solve the complement version of MAST, namely identifying the smallest set of leaves to remove from input trees to obtain isomorphic trees. We also present an
O
(
n
2
+
kn
) algorithm to solve the complement version of MCT. For both problems, we thus achieve significantly lower running times than previously known algorithms. Fast running times are especially important in phylogenetics where large collections of trees are routinely produced by resampling procedures, such as the nonparametric bootstrap or Bayesian MCMC methods.
Algorithms for distributional and adversarial pipelined filter ordering problems
Authors: Condon Anne , Deshpande Amol , Hellerstein Lisa , Wu Ning
Published: April 2009

Pipelined filter ordering is a central problem in database query optimization. The problem is to determine the optimal order in which to apply a given set of commutative filters (predicates) to a set of elements (the tuples of a relation), so as to find, as efficiently as possible, the tuples that satisfy all of the filters. Optimization of pipelined filter ordering has recently received renewed attention in the context of environments such as the Web, continuous high-speed data streams, and sensor networks. Pipelined filter ordering problems are also studied in areas such as fault detection and machine learning under names such as learning with attribute costs, minimum-sum set cover, and satisficing search. We present algorithms for two natural extensions of the classical pipelined filter ordering problem: (1) a
distributional-type
problem where the filters run in parallel and the goal is to maximize throughput, and (2) an
adversarial-type
problem where the goal is to minimize the expected value of
multiplicative regret
. We present two related algorithms for solving (1), both running in time
O
(
n
2
), which improve on the
O
(
n
3
log
n
) algorithm of Kodialam. We use techniques from our algorithms for (1) to obtain an algorithm for (2).
Provably correct on-chip communication
Authors: Avnit K. , D'silva V. , Sowmya A. , Ramesh S. , Parameswaran S.
Published: April 2009

Hardware module reuse is a standard solution to the problems of increasing complexity of chip architectures and pressure to reduce time to market. In the absence of a single module interface standard, predesigned modules for “plug-and-play” usually require a converter between incompatible interface protocols. Current approaches to automatic synthesis of protocol converters mostly lack formal foundations and either employ abstractions far removed from the HDL implementation level or grossly simplify the structure of the protocols considered. This work presents a state-machine-based formalism for modeling bus-based communication protocols and a notion of protocol compatibility and of correct conversion between incompatible protocols. This formalism is used to derive algorithms for checking protocol compatibility and for provably correct, automatic converter synthesis. Experiments with automatic converter synthesis between different configurations of widely used commercial bus protocols, such as AMBA AHB, ASB APB, and the Open Core Protocol (OCP) are discussed. The work here is unique in its combination of a completely formal approach and the use of a low abstraction level that enables precise modeling of protocol characteristics that is also close to HDL.
Instrumenting AMS assertion verification on commercial platforms
Authors: Mukhopadhyay Rajdeep , Panda S. K. , Dasgupta Pallab , Gough John
Published: April 2009

The industry trend appears to be moving towards designs that integrate large digital circuits with multiple analog/RF (radio frequency) interfaces. In the verification of these large integrated circuits, the number of nets that need to be monitored has been growing rapidly. Consequently, the mixed-signal design community has been feeling the need for AMS (Analog and Mixed Signal) assertions that can automatically monitor conformance with expected time-domain behavior and help in debugging deviations from the design intent. The main challenges in providing this support are (a) developing AMS assertion languages or AMS verification libraries, and (b) instrumenting existing commercial simulators to support assertion verification during simulation. In this article, we report two approaches: the first extends the
Open Verification Library
(OVL) to the AMS domain by integrating a new collection of AMS verification libraries; while the second extends
SystemVerilog Assertions
(SVA) by augmenting analog predicates into SVA. We demonstrate the use of AMS-OVL on the Cadence Virtuoso environment while emphasizing that our libraries can work in any environment that supports Verilog and Verilog-A. We also report the development of tool support for AMS-SVA using a combination of Cadence NCSIM and Synopsys VCS. We demonstrate the utility of both approaches on the verification of LP3918, an integrated power management unit (PMU) from National Semiconductors. We believe that in the absence of existing EDA (Electronic Design Automation) tools for AMS assertion verification, the proposed approaches of integrating our libraries and our tool sets with existing commercial simulators will be of considerable and immediate practical value.
A cosimulation methodology for HW/SW validation and performance estimation
Authors: Fummi Franco , Loghi Mirko , Poncino Massimo , Pravadelli Graziano
Published: April 2009

Cosimulation strategies allow us to simulate and verify HW/SW embedded systems before the real platform is available. In this field, there is a large variety of approaches that rely on different communication mechanisms to implement an efficient interface between the SW and the HW simulators. However, the literature lacks a comprehensive methodology which addresses the need for integrating and synchronizing heterogeneous simulators, like, for example, the SystemC simulation kernel for HW modules and an instruction set simulator for SW applications, without being intrusive for the HW and SW descriptions involved in the simulation. In this context, this article presents, compares, and integrates in a system-level framework two different co-simulation strategies for modeling, analyzing, and validating the performance of a HW/SW embedded system. Moreover, for both of them, a mechanism is proposed to provide an accurate time synchronization of the HW/SW communication. The first strategy is intended to provide an early cosimulation environment where HW/SW interaction can be validated without involving the operating system. The communication is implemented between a single SW task and a SystemC description of an HW module by exploiting the features of the remote debugging interface of a debugger (the GNU GDB), and by modifying the SystemC simulation kernel. On the other hand, the second strategy is intended to be used in further development steps, when the operating system is introduced to validate the cosimulation between HW modules and multitasking SW applications. In this approach, the communication is implemented via interrupts by using the features offered by the operating system.

Experimental results are reported on two different case studies to analyze and compare the effectiveness of both the approaches.
Dynamic security domain scaling on embedded symmetric multiprocessors
Authors: Inoue Hiroaki , Abe Tsuyoshi , Ishizaka Kazuhisa , Sakai Junji , Edahiro Masato
Published: April 2009

We propose a method for dynamic security-domain scaling on SMPs that offers both highly scalable performance and high security for future high-end embedded systems. Its most important feature is its highly efficient use of processor resources, accomplished by dynamically changing the number of processors within a security-domain (i.e., dynamically yielding processors to other security-domains) in response to application load requirements. Two new technologies make this scaling possible without any virtualization software: (1) self-transition management and (2) unified virtual address mapping. Evaluations show that this domain control provides highly scalable performance and incurs almost no performance overhead in security-domains. The increase in OSs in binary code size is less than 1.5%, and the time required for individual state transitions is on the order of a single millisecond. This scaling is the first in the world to make possible the dynamic changing of the number of processors within a security-domain on an ARM SMP.
Cost minimization while satisfying hard/soft timing constraints for heterogeneous embedded systems
Authors: Qiu Meikang , Sha Edwin H. -M.
Published: April 2009

In high-level synthesis for real-time embedded systems using heterogeneous functional units (FUs), it is critical to select the best FU type for each task. However, some tasks may not have fixed execution times. This article models each varied execution time as a probabilistic random variable and solves
heterogeneous assignment with probability
(HAP) problem. The solution of the HAP problem assigns a proper FU type to each task such that the total cost is minimized while the timing constraint is satisfied with a guaranteed confidence probability. The solutions to the HAP problem are useful for both hard real-time and soft real-time systems. Optimal algorithms are proposed to find the optimal solutions for the HAP problem when the input is a tree or a simple path. Two other algorithms, one is optimal and the other is near-optimal heuristic, are proposed to solve the general problem. The experiments show that our algorithms can effectively reduce the total cost while satisfying timing constraints with guaranteed confidence probabilities. For example, our algorithms achieve an average reduction of 33.0% on total cost with 0.90 confidence probability satisfying timing constraints compared with the previous work using worst-case scenario.
Temperature-aware register reallocation for register file power-density minimization
Authors: Zhou Xiangrong , Yu Chenjie , Petrov Peter
Published: April 2009

Increased chip temperature has been known to cause severe reliability problems and to significantly increase leakage power. The register file has been previously shown to exhibit the highest temperature compared to all other hardware components in a modern high-end embedded processor, which makes it particularly susceptible to faults and elevated leakage power. We show that this is mostly due to the highly clustered register file accesses where a set of few registers physically placed close to each other are accessed with very high frequency. We propose compile-time temperature-aware register reallocation methodologies for breaking such groups of registers and to uniformly distribute the accesses to the register file. This is achieved with
no performance
and
no hardware overheads
. We show that the underlying problem is NP-hard, and subsequently introduce and evaluate two efficient algorithmic heuristics. Our extensive experimental study demonstrates the efficiency of the proposed methodology.
Skew-aware polarity assignment in clock tree
Authors: Chen Po-Yuan , Ho Kuan-Hsien , Hwang Tingting
Published: April 2009

In modern sequential VLSI designs, clock tree plays an important role in synchronizing different components in a chip. To reduce peak current and power/ground noises caused by clock network, assigning different signal polarities to clock buffers is proposed in previous work. Although peak current and power/ground noises are minimized by signal polarities assignment, an assignment without timing information may increase the clock skew significantly. As a result, a timing-aware signal polarities assigning technique is necessary. In this article, we propose a novel signal polarities assigning technique which can not only reduce peak current and power/ground noises simultaneously but also render the clock skew in control. The experimental result shows that the clock skew produced by our algorithm is 94% of original clock skew in average while the clock skews produced by three algorithms (Partition, MST, Matching) in the absence of post clock tuning steps in the previous work are 235%, 272%, and 283%, respectively. Moreover, our algorithm is as efficient as the three algorithms of the previous work in reducing peak current and power/ground noises.
Clustering high-dimensional data
Authors: Kriegel Hans-Peter , Kröger Peer , Zimek Arthur
Published: April 2009

As a prolific research area in data mining, subspace clustering and related problems induced a vast quantity of proposed solutions. However, many publications compare a new proposition—if at all—with one or two competitors, or even with a so-called “naïve” ad hoc solution, but fail to clarify the exact problem definition. As a consequence, even if two solutions are thoroughly compared experimentally, it will often remain unclear whether both solutions tackle the same problem or, if they do, whether they agree in certain tacit assumptions and how such assumptions may influence the outcome of an algorithm. In this survey, we try to clarify: (i) the different problem definitions related to subspace clustering in general; (ii) the specific difficulties encountered in this field of research; (iii) the varying assumptions, heuristics, and intuitions forming the basis of different approaches; and (iv) how several prominent solutions tackle different problems.