bluuebunny/crossref_metadata_2025 huggingface dataset:
Host species specificity of the goldenrod rust fungus and the existence of rust resistance within some goldenrod species
Authors: Heath Michèle C.
Published: April 2008

Five out of six species of goldenrod at a study site in Ontario had rust pustules in the field and also developed pustules after laboratory inoculation with urediospores of a single-pustule isolate of the rust fungus (Coleosporium asterum) obtained from Solidago canadensis. This isolate also successfully infected seedlings of S. canadensis and an additional goldenrod species from British Columbia. Light microscopy revealed low levels of spore germination and high levels of failed infection attempts even on susceptible plants; in S. canadensis, infection commonly failed before the formation of the first haustorium, a phenomenon typical of nonhost resistance and indicative of a degree of nonspecific incompatibility between fungus and host. Only 2 out of over 200 S. canadensis seedlings from Ontario or British Columbia lacked pustules after repeated inoculations compared with 7 out of 36 for Solidago rugosa seedlings from the study site. Microscopically, infection sites in most of these resistant plants resembled those in crop plants with parasite-specific, single-gene resistance. The data raise the possibility that the fungus has exerted a stronger selective pressure for parasite-specific resistance on S. rugosa than on S. canadensis. Key words: Coleosporium asterum, goldenrod, rust fungi, Solidago, specificity.
A new species of Phialocephala (Hyphomycetes)
Authors: Siegfried Amanda L. , Seifert Keith A. , Bilmer Barton C.
Published: April 2008

A new species in the Hyphomycete genus Phialocephala is described. The new species Phialocephala virens produces an intense greyish green to turquoise colour on certain media and has smaller conidia, shorter phialides, and shorter conidiophores than previously described Phialocephala species. Its tolerance to low levels of the antibiotic cycloheximide suggests the fungus may have affinities with species of Ophiostoma. Cultures of the fungus cause a bright green stain when inoculated onto sapwood of some conifers. Key words: Phialocephala virens, new species, Hyphomycetes, sapstain.
Functional and causal relationships between indoor and outdoor airborne fungi
Authors: Li De-Wei , Kendrick Bryce
Published: April 2008

From May to October, relationships of total numbers of airborne fungal propagules between indoor and outdoor sampling sites were very strong, particularly for Alternaria and Leptosphaeria, while that for unidentified ascospores was positive but to a lesser degree. Indoor and outdoor counts of Cladosporium, Epicoccum, Ganoderma, unidentified spores, hyphal fragments, and biodiversity (total number of fungal genera) were also significantly positively related. There appeared to be no functional relationship between Aspergillus/Penicillium conidia in indoor and outdoor air. From November to April, indoor and outdoor counts of Alternaria, Ganoderma, and hyphal fragments displayed negative relationships, but there was a positive correlation for Cladosporium, Epicoccum, Leptosphaeria, unidentified ascospores, total fungal spores, unidentified spores, and biodiversity. Once again, no functional relationship was detected between Aspergillus/Penicillium indoors and outdoors. The functional relationships of airborne fungi with indoor environmental factors are examined and discussed. A lack of causal relationships, as detected by path analysis, indicates that airborne spores of Alternaria, Leptosphaeria, unidentified ascospores, Coprinus, and Ganoderma came mainly from outdoor sources. All path models fitted this hypothesis well, except for Aspergillus/Penicillium. On the other hand, path analysis suggested that there were probably indoor sources of Cladosporium, Epicoccum, Aspergillus/Penicillium, unidentified basidiospores, and unidentified spores. Most of the models explained a large proportion of variance of indoor airborne fungi. Keywords: airborne fungal spores, redundancy analysis, path analysis.
Effects of nutrient amendment and environment on growth and gas exchange for introduced Penniseturn setaceum in Hawaii
Authors: Williams David G. , Black R. Alan
Published: April 2008

We examined the effects of a balanced soil nutrient amendment on photosynthesis, growth, and reproduction for the alien grass Penniseturn setaceum across an altitudinal gradient on the island of Hawaii. Nutrient amendment of plants enhanced aboveground growth, height, and numbers of reproductive tillers and inflorescences similarly across the altitudinal gradient. Nutrient amendment increased aboveground biomass 22 to 25% but had little effect on predawn water potential, leaf nitrogen concentration, or photosynthesis. Leaf nitrogen concentrations declined with altitude (22 ± 0.5 mg/g N at the coastal site; 16 ± 0.1 mg/g N at the subalpine site) and partially compensated for decreases in specific leaf area with altitude. Plants at the subalpine site had high dark respiration rates, low CO2 saturated photosynthetic rates, and low photosynthetic nitrogen use efficiencies compared with plants at lower altitudes. Chilling temperatures or high respiratory rates may limit net carbon uptake and growth for plants at higher altitude relative to plants at lower altitude. Seasonal patterns of net photosynthesis, stomatal conductance, and water potential suggest that drought colimited carbon uptake and growth at the low altitude site. Success of Penniseturn in Hawaii may stem, in part, from its ability to respond morphologically to compensate for heterogeneous nutrient and water availability across different habitats. Keywords: altitude, Hawaii, nutrient amendment, photosynthesis, Penniseturn setaceum, resource limitation.
Response of root and cotton strip decay to nitrogen amendment along a barrier island dune chronosequence
Authors: Conn Christine E. , Day Frank P.
Published: April 2008

The influence of nitrogen amendment on fine root decomposition was evaluated on sites located along a barrier island chronosequence (24-, 36-, and 120-year-old dunes). The degree to which exogenous nitrogen limits decay at each site was evaluated through a fertilization experiment. Decay substrates included native roots and cotton strips that differed in carbon and nitrogen chemistries. Root decay on younger sites (24 and 36 years old) showed a slight but significant increase in native root decay in response to fertilization. Cotton strips decayed significantly faster in response to fertilization on all sites during three different time periods except on the oldest site in the winter–spring. Nitrogen mineralization and soil nitrogen availability responded to fertilization in a manner consistent with nitrogen limitation. Nitrogen immobilization potential was low in unfertilized plots and increased on younger sites as a result of fertilization. Suppressed lignin degradation in 120-year-old dune roots suggested possible negative fertilization effects. Pure cellulose (cotton strips) did not demonstrate this suppression. It was concluded that nitrogen was a limiting factor during root decay in younger sites but not on the older 120-year-old dune site. Keywords: cotton strips, decomposition, lignin, Long Term Ecological Research Site, nitrogen, phosphorus, roots.
Using bud pollinations to avoid self-incompatibility: implications from studies of three mustards
Authors: Cabin Robert J. , Evans Ann S. , Jennings Diane L. , Marshall Diane L. , Mitchell Randall J. , Sher Anna A.
Published: April 2008

Bud pollinations are frequently used to produce selfed progeny in species that have self-incompatible mature flowers. While this technique is useful for generating inbred lines of self-incompatible species, examining the effects of close inbreeding by producing selfed seeds from bud pollinations may potentially be confounded by the consequences of fertilizing immature ovules. We examined this issue in three species of self-incompatible mustards: Lesquerella fendleri, Brassica rapa, and Raphanus sativus. We performed three types of pollinations on five maternal plants of each species: bud self, bud outcross, and mature flower outcross. For Raphanus, we also planted the seeds produced by these crosses and compared their germination percentages and dry mass 6 weeks after planting. In all three species, outcrossed flowers produced significantly more seeds per fruit than either selfed or outcrossed buds. In each species there were no significant differences among the three crosses in mean individual seed mass per fruit. In Raphanus, the dry mass of plants grown from the selfed bud seeds was marginally less (p = 0.079) than that from seeds from the two outcrosses. As a whole, our results indicate that comparing progeny from mature flower pollinations with progeny from selfed buds can be misleading, particularly when comparing seeds per fruit. Keywords: bud pollination, inbreeding, self-incompatible, flower maturity, selfed seeds.
Effects of acorn size on seedling survival and growth in Quercus rubra following simulated spring freeze
Authors: Aizen Marcelo A. , Woodcock Hilary
Published: April 2008

Seed size is an important phenotypic trait commonly associated with the fitness of young seedlings exposed to environmental stress. Spring frosts can cause leaf necrosis and seedling mortality in young oak seedlings, and seedling mortality following spring freeze events is a factor limiting the northern range limits of Quercus gambelii (Nutt.). We examined the relationship between acorn size and seedling survival following spring freeze by exposing 1-month-old Quercus rubra (L.) seedlings from two sites in Massachusetts to −3 °C for 8 h. Mortality of 1-month-old frost-exposed seedlings (20–25%) was 10 times higher than control mortality, with survival directly related to acorn size. Seedling size at the end of the first growing season was negatively affected by frost exposure and positively associated with acorn size. Overwintering mortality (<5%) was negatively associated with seedling size. The production of large acorns should confer a selective advantage in habitats susceptible to spring frosts through a positive effect on seedling establishment success under stress. Keywords: red oak, acorn size, frost, seedling survival.
Identification of RFLP markers linked to a gene for downy mildew resistance (Sdm) in sorghum
Authors: Oh Boung-Jun , Frederiksen Richard A. , Magill Clint W.
Published: April 2008

The Sdm locus in sorghum accession SC325 confers resistance to downy mildew caused by pathotypes 1 and 3 of Peronosclerospora sorghi. Restriction fragment length polymorphism linkage analysis placed the Sdm locus near loci detected by probes pSbTXS552 and pSbTXS361 at 5.0 and 7.9 cM, respectively. Fragment patterns for the cross segregating for disease resistance differed from those for the original mapping cross, preventing assignment of Sdm to a linkage group. Keywords: Peronosclerospora sorghi, resistance, RFLP, linkage, hybrid breeding.
Pollination and seed production in five boreal species of Vaccnium and Andromeda (Ericaceae)
Authors: Fröborg Heléne
Published: April 2008

Using experimental manipulations, I examined if pollen quality affected fruit and seed production in five ericaceous understory shrubs in a coniferous forest in central Sweden. Flowers of Vaccinium myrtillus L., Vaccinium uliginosum L., Vaccinium vitis-idaea L., Vaccinium oxycoccos Gil., and Andromeda polifolia L. were (treatment 1) open-pollinated, (treatment 2) bagged without further treatment, (treatment 3) bagged and self-pollinated, (treatment 4) cross-pollinated with pollen from neighbouring plants, or (treatment 5) supplied with pollen from distant plants. Finally, flowers were (treatment 6) open-pollinated with a supply of extra pollen of distant origin. To investigate pollen or resource limitations to fruit and seed production, V. vitis-idaea was subjected to partial flower removal followed by open- and hand-pollination. Fruit and seed set were estimated for each treatment. The main conclusion is that natural levels of outcrossing are sufficiently high for full seed production and that the availability of pollen is not limiting in natural habitats. There were significant reductions in fruit and seed set after self-pollination in V. myrtillus. Fruit set was reduced in V. vitis-idaea, and V. uliginosum failed to set fruit after self-pollination. Self-pollination caused a decreased seed set in A. polifolia. There was no significant variation across treatments in V. oxycoccos. Since fruits tend to develop regardless of seed number, resources are likely to limit seed production in species with costly fruits. Keywords: self-fertility, pollination, Vaccinium, fruit set, seed set.
"Windows of opportunity" for recruitment in long-lived clonal plants: experimental studies of seedling establishment in Vaccinium shrubs
Authors: Eriksson Ove , Fröborg Heléne
Published: April 2008

Two experiments were performed to analyse seedling recruitment in Vaccinium myrtillus, Vaccinium vitis-idaea, Vaccinium uliginosum, and Vaccinium oxycoccos. The purpose was to examine the probability of recruitment at "windows of opportunity," i.e., spatially or temporally unpredictable conditions in which seedling recruitment is possible within stands of established conspecific adults. Seedling emergence in all four investigated species depended on a combination of seed and microsite (disturbance) availability. In V. myrtillus, which was studied in more detail than the other species, emergence and survivorship were similar on non wood substrate and on decaying wood, but seedling growth was favored on the latter substrate. An experiment along an environmental gradient with all four species showed that recruitment required approximately similar conditions even though the adults of the species exhibited a clear zonation along the gradient. For all species except V. oxycoccos, recruitment was confined to only a part of the adults' range. Vaccinium species are generally good seed dispersers and have a high fecundity but usually lack developed seed banks. This behavior is interpreted as a response to occurring windows of opportunity for recruitment, i.e., small disturbances with high moisture and organic soil content. Recruitment at windows of opportunity is suggested as one distinct pattern of recruitment among clonal plants, along with previously suggested repeated and initial seedling recruitment patterns, and some implications of this distinction are briefly discussed. Keywords: clonal plants, genets, life histories, population dynamics, seedling establishment, Vaccinium.
Effect of the herbicide Pyradur on host cell wall degradation by the sugarbeet pathogens Rhizoctonia solani and Sclerotium rolfsii
Authors: El-Abyad Mohamed S. , Abu-Taleb Amira M. , Abdel-Mawgood Tarek
Published: April 2008

Pyradur applied to soil at 0.6–2.4 µg∙g−1 active ingredients suppressed infection of three sugarbeet cultivars by Rhizoctonia solani and Sclerotium rolfsii. In the absence of Pyradur, R. solani was more virulent than S. rolfsii against 'Raspoly' and 'TOP', whereas S. rolfsii was more virulent than R. solani against ‘Tribel’. Virulence was directly correlated with the activities of cell wall degrading enzymes produced by mese pathogens in vivo and on cell walls in vitro. Reduced virulence of R. solani and S. rolfsii under Pyradur stress was due to decreased inoculum potential of the two pathogens at the utilized concentrations of herbicide in situ and to reduced production of cell wall degrading enzymes in vitro and in host tissues. In addition, shifts in the pH of cell wall amended media, because of changes in the nature of metabolic products of the pathogens under Pyradur stress, suggest possible repression or stimulation of the activity of the enzymes involved in degradation in vivo, of which cellulase and polygalacturonase are favoured by acid conditions, and galactanase, mannase, and pectate lyase are favoured by alkaline conditions. Keywords: sugarbeet, Rhizoctonia solani, Sclerotium rolfsii, Pyradur, metolachlor, chloridazon, growth activities, pathogenicity, virulence, cell wall enzymes.
La variation des caractères épidermiques foliaires chez le Festuca rubra sensu lato (Poaceae) dans l'est du Canada
Authors: Dubé Martin , Morisset Pierre
Published: April 2008

The variation structure of epidermal characters in Festuca rubra in Eastern Canada is compared with the structure produced by morphology and anatomy. This study is based on 94 specimens including native and introduced variants as well as hybrids. The characters best separating these variants are selected by a series of discriminant analyses. Epidermis then appears as useful as anatomy and morphology in establishing a taxonomical system in this aggregate of taxa. Keywords: Festuca rubra, epidermis, anatomy, morphology, discriminant analysis.
Population ecology of Cirsium pitcheri on Lake Huron sand dunes I. Impact of white-tailed deer
Authors: Phillips Tracy , Maun M. A.
Published: April 2008

Cirsium pitcheri is a monocarpic perennial endemic to the shorelines of the Great Lakes, primarily Lakes Huron and Michigan. Its populations are being reduced by anthropogenic impact and deer grazing throughout much of its range. Several of its once abundant populations at some locations have been extirpated. The species is listed as threatened and endangered in Canada and the United States, respectively. Greenhouse studies were conducted to determine the effects of simulated herbivory by white-tailed deer on the survival, growth, and compensatory ability of plants. We found mat Cirsium pitcheri possessed good ability to compensate for tissue loss. However, simulated intensive browsing resulted in significant reductions in root dry weight. Since the flowering ability of monocarpic perennials such as Cirsium pitcheri is dictated by the amount of stored root reserves, such reductions in root biomass may delay the onset of flowering, reduce overwinter survival, and affect the future growth and survival of this threatened species. Keywords: white-tailed deer, browsing, defoliation, compensation, Cirsium pitcheri, Pitcher's thistle.
Canavirgella banfieldii gen.and and sp.nov.: a needlecast fungus on pine
Authors: Merrill W. , Wenner N.G. , Dreisbach T.A.
Published: April 2008

Canavirgella banfieldii gen. and sp.nov. (Ascomycetes: Rhytismatales) is a previously undescribed needlecasl fungus attacking Pinus strobus throughout the eastern U.S.A. from North Carolina to Maine. Pinus peuce was severely infected in northern Vermont. Hysterothecia average 3.2 cm long and are epiphyllous, subhypodermal, and dematiaceous, with clavate asci bearing short rod-shaped ascospores. Pycnidia are epiphyllous, subhypodermal, concolorous, blisterlike with one or more pores, and produce minute bacillar conidia. These characteristics separate this fungus from existing genera as presently defined. Keywords: Canavirgella banfieldii, Pinus strobus, Pinus peuce, needlecast.
Environmental filters and seedling recruitment on a coastal dune in subarctic Quebec (Canada)
Authors: Houle Gilles
Published: April 2008

One important factor that often determines the presence of a plant species on a site is propagule availability. Afterwards, abiotic and biotic factors act as a series of filters operating sequentially from the seed to the adult stage, determining the pattern of recruitment. By comparing the spatial pattern of emerging seedlings to those of seed availability and of surviving seedlings, one can determine the relative importance of the environmental filters acting on the seed germination and the seedling establishment phases. On a coastal dune system in subarctic Quebec (Canada), sand accumulation, salt spray, and substrate physicochemistry, all affecting microsite quality for seeds and seedlings, vary along a short topographical gradient. My goal was to determine whether or not conditions changing along this gradient differentially affect the initial stages of population recruitment of two perennial herbaceous species for which adults are segregated along the gradient: Honckenya peploides and Elymus mollis. The spatial pattern of seeds in the seed bank and that of emerging seedlings were not related to one another for either Honckenya or Elymus. However, patterns of surviving seedlings were spatially correlated with those of emerging seedlings. Seed and seedling mortality were not density dependent; they were both spatially variable, although not clinal. These results suggest that the environmental filters acting on the germination stage are those that determine the spatial patterns of recruitment. Spatial segregation along the flank of the foredune between adults of the two species studied thus seems to be maintained in part (and maybe reinforced) by low seed mobility, or low seed retention, and the availability of suitable microsites for seed germination. Population progression towards the upper beach seems to depend mostly on seedling establishment for Honckenya but on clonal growth for Elymus. Keywords: Elymus mollis, Honckenya peploides, Hudson Bay, partial Mantel test, spatial segregation, Whapmagoostui-Kuujjuaraapik.
Variation in lake sturgeon (Acipenser fulvescens) abundance and growth among river reaches in a large regulated river
Authors: Haxton Tim J , Findlay C Scott
Published: April 2008

Lake sturgeon (Acipenser fulvescens) stocks are well below historical levels across their natural range. In this study, we examine why lake sturgeon have not substantially recovered to historical levels in a large regulated river (Ottawa River, Canada). Three primary anthropogenic stressors have been identified as potentially limiting lake sturgeon populations in the Ottawa River: (i) commercial harvest, (ii) contaminants, and (iii) water power management. Hypotheses i and iii were tested by comparing lake sturgeon abundance and examining growth among reaches differing in level of commercial harvest and water management regime; hypothesis ii was tested by assessing contaminant loads in lake sturgeon and examining effects on growth and condition. Relative abundance, growth, mortality, and mean size of lake sturgeon did not differ among river reaches with (n = 6) and without (n = 3) a commercial harvest. Mercury was the only contaminant that was elevated. Neither growth nor condition showed any detectable relationship with mercury body burden. Relative abundance of lake sturgeon was greater in unimpounded than impounded reaches; additionally, there is evidence of faster growth in the impounded versus unimpounded reaches, suggesting density-dependent compensation. Water power management appears to be the primary factor affecting lake sturgeon in this river.
Depth-integrated, continuous estimates of metabolism in a clear-water lake
Authors: Coloso James J , Cole Jonathan J , Hanson Paul C , Pace Michael L
Published: April 2008

High-frequency dissolved oxygen (DO) measurements have been used for estimating gross primary production (GPP) and respiration (R) in lake ecosystems. Most researchers have determined GPP and R only in surface waters, a practice that may underestimate R in general and GPP in clear-water lakes in particular. We deployed oxygen sondes at multiple sites and depths in a clear-water lake. Rates of GPP or R were similar horizontally over the surface waters of the lake. Diel DO signals weakened with depth; however, removing noise from the data, by either wavelet transforms or moving averages, enhanced our ability to resolve diel metabolic signals. While GPP declined sharply with depth, R was unrelated to depth. The majority of GPP and R occurred in the upper mixed layer, but deeper water accounted for 14%–28% of GPP and 20%–43% of R, depending on the statistical filtering technique used. GPP and R were nearly in balance in the surface waters, but for the entire lake R exceeded GPP, and net ecosystem production was negative. Deployment of oxygen sondes in various habitats and at multiple depths allows for a more complete estimate of whole-lake metabolism and a better understanding of the spatial and temporal complexity of lakes.
Assessment of analytical tools used to estimate the stiffness of asphalt concrete
Authors: Zeghal Morched , ElHussein H. Mohamed
Published: April 2008

This paper presents the results of an assessment performed on the empirical model used in level 3 input of the proposed mechanistic–empirical pavement design guide (MEPDG) developed under the National Cooperative Highway Research Program (NCHRP) project 1-37A. The empirical formula estimates the stiffness (dynamic modulus) of asphalt concrete mixes used in paving roads. The assessment revealed that analytically estimated dynamic modulus differs substantially from the actual value determined in the laboratory. Errors are high at elevated service temperatures and for mixes prepared with engineered binders. An alternative approach is presented in this paper based on the use of generic modulus values. Generic asphalt concrete dynamic modulus values were generated from tests performed on typical Marshall and SuperPave mixes. Results were compiled in a database (material library) to provide users of the MEPDG with estimates of the dynamic modulus that will yield more accurate predictions of performance until dynamic modulus laboratory testing capabilities are established locally.
Experimental investigation of the effects of turbulence intensity on frazil ice characteristics
Authors: Clark Shawn , Doering John
Published: April 2008

The counter-rotating flume at the University of Manitoba was used to conduct a series of 21 laboratory experiments to investigate the effects of turbulence intensity on frazil ice formation and evolution. A detailed study of the velocity and turbulence intensity distributions within the counter-rotating flume was initially conducted using a constant-temperature anemometer equipped with a one-dimensional conical hot-film probe. Five levels of turbulence intensity were generated by five different sets of bed plates and flume wall rotation rates in order to study how turbulence affected the frazil particle size distributions and the statistics related to clear disk-shaped particles. It was found that a lognormal distribution could not be rejected when describing the frazil particle size distributions, regardless of the turbulence intensity of the water. The variation of the mean and standard deviation of particle diameter with turbulence intensity are well described by a parabolic shape. A preliminary equation to describe the variation of the mean and standard deviation of particle diameter as a function of turbulence intensity and time is presented.
New paradigms for public procurement of construction projects in the United Kingdom — potential applicability in Spain
Authors: de la Cruz M. Pilar , del Caño Alfredo , de la Cruz Elisa
Published: April 2008

The authors have studied the construction-related public procurement environment in the United Kingdom to identify and analyze potential improvement strategies that may be applied in Spain. The paper comprises a comparative analysis of the environments in both countries. It focuses on recent programs to enhance the efficiency of the British administration, and includes suggestions for improving those programs and the main keys to their success. A Delphi analysis was carried out in Spain to assess, in qualitative terms, how efficiently and easily those strategies could be implemented there. The results indicate that, if implemented, many of those potential strategies would pose significant difficulties in the short and medium term. Therefore, the reasons for those feasibility problems are summarized. In any case, specific strategies used in the UK environment, explained here, could be useful for Spain and other countries with similar characteristics.
Service-life assessment of building components: application of evidence theory
Authors: Talon A. , Boissier D. , Lair J.
Published: April 2008

This paper deals with the assessment of the service life of in-service building components subjected to known environmental and usage conditions. This assessment is complex because of two primary features. First, the assessment has to be carried within a multiscale context: a geometric scale that ranges from the material or elemental to building scale; a range in the complexity of the degradation (phenomena that varies from a single phenomenon to the consideration of several degradation scenarios); a range of possible performance requirements, from one function to several; and consideration, as well, to the time over which the process is carried out that may span from the design stage to that of management and repair. Second, this assessment must also take into consideration the availability and features of service-life data that by nature is heterogeneous, imprecise, uncertain, and incomplete. In this context, a comprehensive methodology is developed using all available data on service life derived from existing methods of service-life assessment of materials, elements or building components. Such data may, for example, be extracted from fundamental studies on durability, accelerated short-term exposure tests, statistical methods, factorial methods, feedback from practice, or expert opinion or other sources. The main stages of this methodology are: (i) identification of all possible degradation scenarios provided by failure mode and effects analysis (FMEA); (ii) collection of all available service-life data (SL-data) associated with these degradation scenarios, transformation of this data into a fuzzy-set format, and assessment of its quality; (iii) processing of unification of data and aggregation of data; and (iv) assessment of the service life of building components. The case study of a window unit allows for: (i) service-life assessment of a building component to be processed by unification of data and aggregation of data and (ii) a conclusion to be deduced.
Le biodiesel. II. Production — une synthèse
Authors: Nikiema J. , Heitz M.
Published: April 2008

Biodiesel is a biofuel obtained from vegetable or animal oils and fats. These are mainly composed of triglycerides but can contain significant amounts of water and free fatty acids, depending on their origin. Biodiesel is generally produced by transesterification, with or without catalyst, by enzymatic interesterification, by microemulsification, or by pyrolysis. Transesterification (with acid, basic, or enzymatic homogeneous or heterogeneous catalysts) is the most frequently used reaction. The operating parameters, including the types and concentrations of alcohol and catalyst, the reaction temperature and duration as well as the agitation intensity, must be optimized for successful application. In general, biodiesel is characterized by a higher viscosity and a lower heating value than those of petrodiesel. To improve these physical properties, petrodiesel or additives can be added to biodiesel.
Irreversibility analysis of variable viscosity channel flow with convective cooling at the walls
Authors: Makinde O D
Published: April 2008

This study investigates the inherent irreversibility in the flow of a variable (temperature-dependent) viscosity fluid through a channel with parallel plates. The channel is narrow so that the lubrication approximation may be applied, and the temperature-dependent nature of viscosity is assumed to follow an exponential model. The system is assumed to exchange heat with the ambient surroundings following Newton’s cooling law. Using a perturbation method coupled with a special type of Hermite–Padé approximation technique, the simplified governing nonlinear equations are solved and the important properties of overall flow structure, including velocity field, temperature field, and thermal criticality conditions are derived, which essentially expedite obtaining expressions for volumetric entropy generation numbers, irreversibility distribution ratio, and the Bejan number in the flow field. PACS Nos.: 44.10.+a, 47.11.–j, 47.15.gm
Non-equilibrium emission of neutrons in α-particle induced reactions with holmium
Authors: Agarwal Avinash , Rizvi I A , Chaubey A K
Published: April 2008

The stacked-foil activation technique followed by off line high-purity Ge γ-ray spectroscopy was used for the measurement of the excitation functions for energies up to 50 MeV for the 165Ho(α, 2n) 167Tm, 165Ho(α, 3n) 166Tm, and 165Ho(α, 4n) 165Tm reactions. The measured excitation functions were compared with theoretical predications considering equilibrium as well as pre-equilibrium reaction mechanisms according to the geometry-dependent hybrid (GDH) model of Blann using computer code ALICE-91. The high-energy parts of the excitation functions are due to the pre-equilibrium reaction mechanism, while the low-energy parts are mediated by compound-nucleus decay. It was found that the compound-nucleus-decay mechanism alone is unable to explain the experimental trend of our data. The pre-equilibrium fraction was also calculated. PACS Nos.: 22.55.–e, 27.60.+j
Intra-terrestrial verification of the gravitational shift
Authors: Sfarti Adrian
Published: April 2008

Einstein predicted a change in the energy of photons in the proximity of a gravitational field, the change being directly proportional to the distance from the gravitational source. In the early 1960s, Pound and Rebka (Phys. Rev. Lett. 3, 439 (1959)) set out to verify Einstein's prediction. The experiment was reprised with even higher precision by Pound and Snider (Phys. Rev. Lett. 13, 539 (1964)). Later, Vessot (Phys. Rev. Lett. 45, 2081 (1980)) reprised the experiment in space at a much improved precision. In this paper, we will present an approach to the experiment that goes exactly in the opposite direction by descending towards the center of the Earth. Our new approach is less expensive, introduces stronger effects, and showcases an unprecedented second-order effect. PACS No.: 03.30.+p
Theoretical calculations of transition probabilities for individual and multiplet lines between some excited levels of atomic potassium
Authors: Çelik Gültekin , Ateş Şule
Published: April 2008

The transition probabilities for individual and multiplet lines between some excited levels of atomic potassium are calculated using weakest bound electron potential model theory (WBEPMT). The numerical nonrelativistic Hartree–Fock wave functions for the expectation values of radii in all excited states, unlike the Numerical Coulomb Approximation method traditionally used for WBEPMT and experimental ionization energies, have been employed to determine the parameters. The results obtained during this work agree very well with the accepted values taken from National Institute Standards and Technology. Moreover, some transition probabilities not existing on the data bases for highly excited levels in atomic potassium have been obtained using this method. PACS No.: 32.70.Cs
Five-day planetary waves as seen by the Odin satellite and the ground-based Kiruna millimeter wave radiometer in January–March 2005
Authors: Belova Alla , Kirkwood Sheila , Raffalski U , Kopp Gerhard , Hochschild Gerd , Urban Joachim
Published: April 2008

The signature of five-day planetary waves in ozone and temperature data from the advanced sub-millimeter radiometer aboard the Odin satellite is examined. The period January–March 2005 and heights from 24–56 km are used. We find highest wave amplitudes in both temperature and ozone in the winter hemisphere at 60°N-70°N. The relative phases between ozone and temperature perturbations show the expected antiphase behaviour in the photochemistry-dominated region at about 40 km altitude. We compare the global planetary wave properties from Odin with five-day perturbations in ozone measured by the millimeter wave radiometer in Kiruna (KIMRA, 67°N, 20°E). In the early part of the comparison interval (January–February) at 40 km, we find good correlation between the two in terms of both phase and amplitude of the perturbations. In the latter part of the comparison interval (March) where mean ozone levels are higher, the amplitudes of the ozone five-day perturbations over Kiruna are much higher than the wave amplitudes found using Odin. We conclude that five-day variations in ozone due to planetary waves can be detected by KIMRA in some circumstances, but that other sources of variability dominate at other heights and times. PACS No.: 94.10.Jd
Spectra of Ni- and Co-like ions of Xe in an electron-beam ion trap
Authors: Träbert E , Beiersdorfer P , Gu M F
Published: April 2008

High-resolution soft X-ray observations of Ni- and Co-like Xe ions in an electron-beam ion trap are compared with the predictions of various calculations. Calculated energy levels up to the 4p levels are presented alongside experimental determinations. PACS Nos.: 32.30.Rj; 34.50.Fa; 34.80.Dp
Patterns of parasitism and body size in red squirrels (Tamiasciurus hudsonicus)
Authors: Gorrell Jamieson C. , Schulte-Hostedde Albrecht I.
Published: April 2008

Parasites use their hosts for nutrition, shelter, and even dispersal; the latter can result in sex-biased parasite distribution. Host sex-biased parasitism has been well documented in vertebrates, including mammals, and males are often more parasitized than females. Male-biased parasitism is often attributed to sexual size dimorphism, with larger animals being more parasitized. Here, we used a natural population of red squirrels ( Tamiasciurus hudsonicus (Erxleben, 1777)), a species without sexual size dimorphism, to test for sex-biased parasitism in ectoparasites and intestinal helminth parasites. We also tested for size-dependent parasitism to determine the importance of body size on parasitism. We predicted that males would be more parasitized and that larger individuals would be more parasitized. As well, we predicted a male-biased flea distribution on male squirrels. Parasitism fluctuated over the course of 4 months, with flea infection peaking in August and helminth infection peaking in June. We found evidence of male-biased parasitism in helminth and ectoparasite infections. Flea infection was weakly correlated with body size in females but not in males, while no correlation was found between body size and helminth infection. Lastly, fleas had a female-biased population; however, male fleas were more likely to be found on male squirrels, and this could be to maximize dispersal to avoid inbreeding.
Biogeography of the deepwater sculpin (Myoxocephalus thompsonii), a Nearctic glacial relict
Authors: Sheldon T. A. , Mandrak N. E. , Lovejoy N. R.
Published: April 2008

Although the freshwater fish fauna of North America is relatively well studied, the biogeography of the deepwater sculpin ( Myoxocephalus thompsonii (Girard, 1851)) remains poorly understood. Collections of the species are limited, both because of its relatively remote distribution and because its habitat at the bottom of very deep lakes presents considerable logistic challenges for sampling. To investigate the biogeography of the deepwater sculpin, we conducted a range-wide (excluding the Laurentian Great Lakes) survey for the species between May and October 2004. Deepwater sculpin were collected using a variety of sampling gears, including a trap that was specifically designed to capture the species. We hypothesized that deepwater sculpin would be found only in areas that were formerly occupied by glacial lakes or the Champlain Sea. We reconstructed the historical boundaries of these water bodies and found that nearly all lakes where deepwater sculpin were collected, including four new localities, were within those limits. Conversely, the species was not detected in sampled lakes that were beyond these boundaries. Our results clarify the distribution and biogeography of the deepwater sculpin and strengthen the view that the current distribution of the species was mediated by dispersal through glacial lakes and the Champlain Sea.
Deer mouse demography in burned and unburned forest: no evidence for source–sink dynamics
Authors: Zwolak Rafał , Foresman Kerry R.
Published: April 2008

Deer mouse ( Peromyscus maniculatus (Wagner, 1845)) populations increase dramatically after wildfires. These increases are puzzling because there are no obvious food sources or vegetation cover in severely burned areas. We conducted a capture–mark–recapture study of deer mice in a mosaic of burned and unburned montane forests in western Montana to determine if their postfire increase could be explained by source–sink dynamics, with burned areas acting as a sink. When overall mouse densities were very low, the vast majority of the population was found in burned areas. Mice appeared regularly in unburned forest only when the densities were high. This pattern is precisely opposite to the expected results if the sink hypothesis were correct. Moreover, mice in burned areas did not show decreased body mass, reproductive performance, or survival when compared with mice in unburned areas. Age structure and sex ratio did not differ between burned and unburned sites. We conclude that burned areas do not function as population sinks; rather, they represent high-quality habitat for deer mice.
The effects of El Niño on the foraging behavior of lactating California sea lions (Zalophus californianus californianus) during the nonbreeding season
Authors: Melin S. R. , DeLong R. L. , Siniff D. B.
Published: April 2008

We compared the nonbreeding-season foraging behavior of lactating California sea lions ( Zalophus californianus californianus (Lesson, 1828)) at San Miguel Island, California, during El Niño conditions in 1993 and non-El Niño conditions in 1996. Lactating females were instrumented with satellite-linked time–depth recorders between January and March in 1993 (n = 6) and 1996 (n = 10) and data were collected through May in each year. Females foraged northwest of the colony, up to 367 km from it and 230 km from the California coast. Mean dive depths ranged from 19.5 to 279.3 m, but most females achieved dives deeper than 400 m. Most females fed exclusively in the offshore habitat, traveled farther from the colony, spent more time traveling, made deeper and longer dives, and terminated lactation earlier during the 1993 El Niño. The results suggest that prey were concentrated in the offshore habitat and located farther from the colony and deeper in the water column during El Niño. Females did not change their foraging direction, foraging-trip duration, foraging effort, or prey species consumed.
Changes in response to odors during the reproductive period in male and female prairie voles (Microtus ochrogaster)
Authors: Yamoah D. , Williams-Baginski K. , Bamshad M.
Published: April 2008

In prairie voles, Microtus ochrogaster (Wagner, 1842), the onset of parental caring differs by sex and reproductive condition. Maternal caring is displayed abruptly at parturition, whereas paternal caring intensifies gradually during the reproductive period. To determine if changes in odor responsiveness contribute to sex differences in onset of parental behavior, voles were given a choice to investigate various odors at different times during the reproductive cycle. Subjects were either sexually naïve or mated. Mated pairs cohabited until mid-gestation, late gestation, or 3 days postpartum. Voles crossed a tunnel to explore a row of three filter papers covered with infant odor, orange extract, or saline. Males and females exhibited different odor preferences. Males preferred infant odor to saline and orange extract, whereas females preferred infant odor and saline to orange extract. Mating changed the odor investigative behaviors in both males and females. Some voles vigorously manipulated odor-covered papers. The number of females manipulating the papers increased abruptly at late gestation. The number of males manipulating the papers was particularly high at mid-gestation and after the birth of young. Results suggest that mating and cohabitation in prairie voles influences odor responses in a sex-specific manner.
Social structure of Risso’s dolphins (Grampus griseus) at the Azores: a stratified community based on highly associated social units
Authors: Hartman K. L. , Visser F. , Hendriks A. J.E.
Published: April 2008

In this study, we present for the first time a model for the social structure of Risso’s dolphins ( Grampus griseus Cuvier, 1812). Over the period 2004–2006, 1028 Risso’s dolphins were identified at Pico island, Azores. Individuals sighted on 10 or more occasions were included in the analysis of social structure (n = 183). High resighting rates indicate strong site fidelity for at least part of the population. We found that individuals form stable, long-term bonds organised in pairs or in clusters of 3–12 individuals. Social structure is stratified based on age and sex classes, with strong associations between adult males and between adult females. We suggest that clusters form the basic units of Risso’s dolphin society. Thirteen pods consisting solely of adults, likely males, and 3 pods consisting of mother–calf pairs were identified. Males are organised in stable, long-term associations of varying size that occur throughout the complete range of behavioural states observed. For females, associations can be of similar strength, but the time scale may vary depending on the presence of nursing calves. As subadults, associations also occur (pair formation), but are less stable than those observed for adults. We propose a new model for Risso’s dolphin societies known as a stratified social organisation, which differs from the fission–fusion and matrilineal society models.
Comparative swimming effort of migrating gray whales (Eschrichtius robustus) and calf cost of transport along Costa Azul, Baja California, Mexico
Authors: Rodríguez de la Gala-Hernández S. , Heckel G. , Sumich J. L.
Published: April 2008

Swimming velocities and breathing rates were measured for migrating gray whales ( Eschrichtius robustus (Lilljeborg, 1861)) at Costa Azul, Baja California, to compare swimming effort of southbound whales, northbound whales without calves, and northbound mothers and calves. From December 2004 to May 2005, whales were followed using a theodolite to determine swimming velocity. Binoculars were used to count whale blows and their timings were recorded to determine breathing rates. Individual whale breathing rates (BR) were divided by their swimming velocity (V) to derive a comparative index of swimming effort in units of breaths per kilometre. There were significant differences in mean BR, V, and swimming effort among the three migrating groups (p < 0.05). Southbound migrating whales averaged a swimming effort of 7.4 breaths·km–1(V = 1.9 m·s–1, BR = 0.8 breaths·min–1). Northbound whales without calves showed the lowest swimming effort of the three migrating groups (4.7 breaths·km–1, V = 1.8 m·s–1, BR = 0.5 breaths·min–1). Northbound mothers and calves had the same swimming velocity (V = 1.2 m·s–1), but BR and swimming effort were calculated separately yielding a swimming effort of 7.6 breaths·km–1(BR = 0.5 breaths·min–1) for mothers and 10.1 breaths·km–1(BR = 0.7 breaths·min–1) for calves. Cost of transport was calculated for northbound calves, yielding a range based on 1.5% and 3% tidal volumes of 0.25–0.34 and 0.51–0.58 J·kg–1·m–1, respectively.