bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental evidence of reduction in attractive and repulsive forces between clay particles permeated with organic liquids
Authors: Kaya Abidin , Fang Hsai-Yang
Published: May 2005

Researchers have investigated the engineering properties of clayey soils with organic fluids to evaluate the performance of earth structures affected by chemical spills or leachate. Reported results show that when the pore water of clayey soils was replaced with organic liquids, the engineering properties of clayey soils, such as hydraulic conductivity and stressstrain behavior, varied significantly and were similar to those of fine sand  silt. Variations in the engineering properties were mainly attributed to flocculation of particles due to decreases in the attractive and repulsive forces between the particles without showing any direct experimental evidence. In this study, flocculation of kaolinite and bentonite particles was investigated in the presence of water and organic liquids using an optical microscope (OM), and the first experimental evidence of soil flocculation due to pore fluid is presented. The OM results reveal that when the pore water of the soil is replaced with organic fluids, the soil particles flocculate and form a clustered structure with large pores within the flocs. The results also indicated that the degree of flocculation and the size of the formed cluster depend on the type of clay mineral and the characteristics of the organic liquid.Key words: clayey soils, organic liquids, engineering properties, attractive and repulsive forces, optical microscope.
Response of a residual soil slope to rainfall
Authors: Rahardjo H , Lee T T , Leong E C , Rezaur R B
Published: May 2005

Rainfall-induced landslides are a common problem in residual soil slopes of the tropics. It is widely known that rainfall-induced slope failures are mainly caused by infiltration of rainwater; however, the response of a residual soil slope to infiltration is not fully understood. The difficulties lie in the quantification of the flux boundary condition across the slope surface with respect to infiltration and its effect on the pore-water pressure conditions in the slope. Therefore, it is important to understand the response of a slope to different rainfall conditions and the resulting changes in pore-water pressures and water contents. A residual soil slope in Singapore was instrumented with pore-water pressure, water content, and rainfall measuring devices, and studies were carried out under natural and simulated rainfalls. Results indicate that significant infiltration may occur in a residual soil slope during a rainfall. Small total rainfalls can contribute a larger infiltration percentage than large total rainfalls. The percentage of infiltration usually decreases with increasing total rainfalls. The study has indicated the existence of a threshold rainfall of about 10 mm for runoff generation to commence. Infiltration during wet periods may lead to the development of positive pore-water pressures as a consequence of a perched water table condition. Matric suctions are recovered gradually during dry periods due to redistribution. Soil water contents tend to be higher near the toe of the slope than at the crest irrespective of rainfall events, indicating subsurface movement of water in the downslope direction. The study has also indicated a correlation between rainfall amount and relative increase in pore-water pressure. The results can be used to quantify the flux boundary conditions required for the seepage analyses associated with rainfall-induced slope failures.Key words: infiltration, pore-water pressure, water content, residual soil, rainfall-induced slope failures.
Correlations between P-wave velocity and Atterberg limits of cohesive soils
Authors: Fener Mustafa , Kahraman Sair , Bay Yakup , Gunaydin Osman
Published: May 2005

Undisturbed and disturbed samples of cohesive soils were collected from eight different locations to investigate the possibility of estimating the Atterberg limits of cohesive soils from P-wave velocity measurements. Each soil type was classified according to the Unified Soil Classification System, and then Atterberg limits of soils were determined and P-wave velocity measurements carried out on the undisturbed samples of each soil type. P-wave velocity values were correlated with the corresponding values of Atterberg limits. It was found that liquid limit, plastic limit, and plasticity index exhibit good correlations with P-wave velocity. The relations follow a logarithmic function. Liquid limit, plastic limit, and plasticity index decrease with an increase in P-wave velocity. In addition, liquid limit, plastic limit, and plasticity index exhibit very good correlations with the ratio of P-wave velocity to water content. Liquid limit, plastic limit, and plasticity index decrease logarithmically with an increase in the ratio of P-wave velocity to water content. It can be concluded that the Atterberg limits of cohesive soils can be predicted from P-wave velocity measurements for preliminary investigations. The developed equations have some limitations and further study is required in this area.Key words: Atterberg limits, cohesive soils, P-wave velocity, regression analysis.
Simplified BNWF model for nonlinear seismic response analysis of offshore piles with nonlinear input ground motion analysis
Authors: Naggar M Hesham El , Shayanfar Mohsen Ali , Kimiaei Mehrdad , Aghakouchak Ali Akbar
Published: May 2005

The seismic response of pile-supported offshore structures is strongly affected by the nonlinear behavior of the supporting piles. Nonlinear response of the pile foundation is the most important source of potential nonlinearity in the dynamic response of offshore platforms to earthquake excitations. It is often necessary to perform a dynamic analysis of offshore platforms that accounts for soil nonlinearity, discontinuity conditions at pilesoil interfaces, energy dissipation through soil radiation damping, and structural nonlinear behaviors of piles. In this paper, an attempt is made to develop an inexpensive and practical procedure, compatible with readily available structural analysis software, for estimating the lateral response of flexible piles embedded in layered soil deposits subjected to seismic loading. In the proposed model a beam on nonlinear Winkler foundation (BNWF) approach, consisting of simple nonlinear springs, dashpots, and contact elements, is used. This model was incorporated into a finite element program, ANSYS, which was used to compute the response of laterally excited piles. A nonlinear approach was used for seismic free-field ground motion analysis. The computed responses compared well with the centrifuge test results. This paper deals with the effects of free-field ground motion analysis on nonlinear seismic behavior of embedded piles. Different parts of a BNWF model, together with quantitative and qualitative findings and conclusions for dynamic nonlinear response of offshore piles, are discussed and addressed in detail.Key words: nonlinear, seismic response, offshore piles, seismic pilesoil interaction, BNWF models.
Consolidation of a soil layer subsequent to cessation of deposition
Authors: Zhu Guofu , Yin Jian-Hua
Published: May 2005

It is necessary in certain cases to estimate the progress of consolidation in a soil layer that has ceased increasing in thickness over time. In this paper, the existing excess pore pressures for two timethickness relations are used as the "initial" pore pressures for analysing the consolidation of soil subsequent to the cessation of deposition. Average degrees of consolidation of the soil layer are presented for one-way drainage and two-way drainage boundary conditions. The average degrees of consolidation are compared with those for uniform and triangular initial excess pore pressure distributions. It is found that the average degree of consolidation for one-way drainage boundaries can be estimated using the value for the triangular distribution. The average degree of consolidation for two-way drainage boundaries is bound by the averages for both the uniform and the triangular initial excess pore pressure distributions.Key words: consolidation, deposition, drainage, settlement, soil.
A generalized thermal conductivity model for soils and construction materials
Authors: Côté Jean , Konrad Jean-Marie
Published: May 2005

This paper intends to develop a generalized thermal conductivity model for moist soils that is based on the concept of normalized thermal conductivity with respect to dry and saturated states. This model integrates well the effects of porosity, degree of saturation, mineral content, grain-size distribution, and particle shape on the thermal conductivity of unfrozen and frozen soils. The thermal conductivity for saturated soils is computed with the use of a well-known geometric model that includes the unfrozen water content in frozen fine-grained soils. Nearly 220 experimental results available from the literature were analysed to develop a generalized empirical relationship to assess the thermal conductivity of dry soils. A general relationship between the normalized thermal conductivity of soils and the degree of saturation using a soil-type dependent factor was used to correlate the normalized thermal conductivity for more than 650 test results for unfrozen and frozen moist soils, such as gravels, sands, silts, clays, peat, and crushed rocks.Key words: heat transfer, soils, degree of saturation, mineral content, unfrozenfrozen, thermal conductivity.
Electrical property measurements using a modified hydraulic oedometer
Authors: McCarter W J , Blewett J , Chrisp T M , Starrs G
Published: May 2005

The work presented focuses on modifying a hydraulic oedometer (Rowe cell) to facilitate monitoring of the electrical conductivity of soil, in conjunction with loaddeformation characteristics. Technical issues are addressed and data presented to show the change in the electrical properties of saturated clay, both parallel and normal to the direction of loading, taken through a loadingunloadingreloading cycle. The electrical response can be interpreted in terms of bulk changes in porosity  void ratio and fabric features such as pore tortuosity and particle alignment. The modified cell and testing methodology offer scope for development as a noninvasive, real time monitoring technique to study fabric changes in soil.Key words: clay, electrical conductivity, consolidation, porosity, fabric, anisotropy.
Étude expérimentale des phases de creusement d'un tunnel à l'aide d'un modèle réduit bidimensionnel
Authors: Dolzhenko N , Mathieu P
Published: May 2005

The main purpose of this experimental and numerical work is to simulate the movements of the soil occurring during the construction of a shallow tunnel in a granular soil, and especially the phases of deconfining and reconfining due to the boring of a tunnel corresponding to the real phases of the construction work. The experimental device used is a small-scale two-dimensional model of a tunnel bored in the analogue soil of TaylorSchneebeli soil consisting of metallic rods. The analysis of the tests is carried out using the numerical imagery which allows visualization of the complete displacement field in the soil mass obtained during the tests. The influence of the tunnel depth on the width of the surface depression and on the maximum surface settlement is presented.Key words: tunnels, soilstructure interaction, digital image, deformation, small-scale model.[Journal translation]
Influence of fines on frost heave characteristics of a well-graded base-course material
Authors: Konrad J -M , Lemieux N
Published: May 2005

The influence of fines on the frost susceptibility of base-course crushed aggregates was established by laboratory freezing tests simulating closely the thermal conditions in the field. The frost susceptibility of the fines was varied by use of different mixtures of granitic fines and commercially available kaolinite clay. A total of 13 samples with fines content of 5%, 10%, and 15% and kaolinite fractions of 10%, 50%, 75%, and 100% were subjected to four freezethaw cycles. The frost susceptibility of well-graded crushed aggregates increases with increasing fines content and increasing kaolinite fraction. From a quantitative point of view, for a given kaolinite fraction, the segregation potential increases linearly with fines content, until the fines create a matrix in which the coarser particles are embedded. For the material studied, this occurs when the fines content is higher than 15%. For a given fines content, it was also established that the segregation potential increases linearly with kaolinite fraction, indicating the importance of mineralogy. It was also established that appropriate thermal testing conditions need to be adopted to prevent undue pore water extraction from the unfrozen soil close to the frost front during laboratory freezing of unsaturated coarse-grained soils.Key words: coarse grained, soil, frost susceptibility, pavements, laboratory, fines.
Characterization of the angle of repose of binary granular materials
Authors: Chik Zamri , Vallejo Luis E
Published: May 2005

When a heap or pile of granular material accumulates at the toe of a failed slope, the pile rests at its angle of repose. The gradual build up of a heap of soil in the laboratory simulates the formation of the heap at the toe of a slope. In this study, the angle of repose developed by binary granular mixtures of coarse sand (1.16 mm in average diameter) and fine sand (0.10 mm in average diameter) was measured in the laboratory. The influence on the angle of repose by the roughness of the base on which the mixtures were placed was also investigated. When the mixtures were placed on a rough surface, the heap developed its angle of repose by two different modes of failure. When the mixtures were controlled by the coarse sand fraction, failure took place on a layer located at the free surface of the heap. When the fine sand fraction controlled the composition of the mixture, the heap developed its angle of repose after the material failed by lateral spreading. When the mixture was placed on a smooth surface, the heap developed its angle of repose by a single mode of failure, namely lateral spreading at the interface of the mixture and the smooth base. A theoretical analysis relating the angle of repose, the internal angle friction of the mixtures, and the interface basal friction angle is also presented.Key words: angle of repose, binary granular material, quartz sand, angle of internal friction, interface friction angle, Rankine earth pressure theory.
Cyclic loading response of loose air-pluviated Fraser River sand for validation of numerical models simulating centrifuge tests
Authors: Wijewickreme Dharma , Sriskandakumar Somasundaram , Byrne Peter
Published: May 2005

Cyclic loading response of loose Fraser River sand was investigated, as input to numerical simulation of centrifuge physical models, using constant-volume direct simple shear tests conducted with and without initial static shear stress condition. Although the observed trends in mechanical response were similar, air-pluviated specimens were more susceptible to liquefaction under cyclic loading than their water-pluviated counterparts. Densification due to increasing confining stress (stress densification) significantly increased the cyclic resistance of loose air-pluviated sand, with strong implications for the interpretation of observations from centrifuge testing. The stress densification effect, however, was not prominent in the case of water-pluviated specimens. The differences arising from the two specimen reconstitution methods can be attributed to the differences in particle structure and highlight the importance of fabric effects in the assessment of the mechanical response of sands. The initial static shear stresses appear to reduce the cyclic shear resistance of loose air-pluviated sand in simple shear loading, in contrast to the increases in resistance reported on the basis of data from triaxial testing. Data from laboratory element tests that closely mimic the soil fabric and loading modes of the centrifuge specimens are essential for meaningful validation of numerical models.Key words: liquefaction of sands, air-pluviation, cyclic loading, direct simple shear testing, specimen preparation, fabric.
A pore-network model for hydromechanical coupling in unsaturated compacted clayey soils
Authors: Simms P H , Yanful E K
Published: May 2005

The behaviour of deformable unsaturated soils is difficult to characterize with simple relationships. Unsaturated hydraulic properties, namely the soil-water characteristic curve and the hydraulic conductivity function, are dependent on both volume change and degree of saturation, whereas volume change itself often cannot be related to a single stress variable but must be described by independent functions of mechanical loading and suction. It is proposed that a means to obtain these functions is through pore-network modelling, by which it is possible to integrate the phenomena of drainage and volume change and the different effects of suction and mechanical loading. The implementation of a two-dimensional pore-network model is described. A simple algorithm for individual pore volume change is adopted. The model uses pore-size distributions measured by mercury intrusion porosimetry to initially generate the simulated pore grid. Predictions of soil-water characteristic curves, void ratio versus suction curves, pore-size distributions at specific suctions, unsaturated hydraulic conductivity, and compression curves are compared with measured values from two compacted clayey soils.Key words: unsaturated soil, volume change, pore network, soil-water characteristic curve, unsaturated hydraulic conductivity, compacted clay.
Construction and application of a single-molecule fluorescence microscope
Authors: Bagh Sangram , Paige Matthew F
Published: May 2005

In this paper, we describe the construction, optimization, and testing of an epifluorescence microscope that has single-molecule (SM) resolution and sensitivity. The microscope makes use of a novel new type of wide-area charge-coupled device (CCD) photodetector with on-chip multiplier gain. Sensitivity and spatial resolution of the instrument are demonstrated by imaging individual Rhodamine 6G (R6G) molecules and characterizing their basic photophysical behaviour under a variety of imaging conditions. A simple, general method for calibrating the photodetector (correlating CCD counts with incident photons) using a highly attenuated laser beam is presented, and the performance of the photodetector is compared with that of other detectors commonly used in SM fluorescence imaging applications. We also demonstrate the versatility of the microscope system by characterizing the SM photophysical behaviour of several other fluorescent molecules, including bodipy-FL and the enhanced green fluorescent protein (EGFP). Key words: single molecule, fluorescence, microscopy, CCD camera, calibration, photobleaching.
Solid lithium perchlorate as a powerful catalyst for the synthesis of β-aminoalcohols under solvent-free conditions
Authors: Azizi Najmodin , Saidi Mohammad R
Published: May 2005

Lithium perchlorate catalyzed the ring opening of epoxides with amines to provide the corresponding β-aminoalcohols in excellent yields with high regioselectivity. The reaction proceeds rapidly under mild and neutral conditions and worked well with primary, secondary, aliphatic, aromatic, and hindered amines in short times at room temperature, in the absence of solvent.Key words: epoxide, lithium perchlorate, β-aminoalcohols, solvent-free.
Triazene derivatives of (1,x)-diazacycloalkanes. Part III. Synthesis and characterization of a series of 1,4-di[2-aryl-1-diazenyl]piperazines
Authors: Little Vanessa Renée , Tingley Reid , Vaughan Keith
Published: May 2005

Reaction of a series of diazonium salts with piperazine in a 2:1 molar ratio affords excellent yields of the 1,4-di-[2-aryl-1-diazenyl]piperazines (3), which have been characterized by IR and NMR spectroscopy. Structural characterization is supported by elemental analysis or by mass spectrometry with accurate mass measurement of the molecular ion. The protons of the piperazine ring hydrogens give rise to a sharp singlet at ca. 4 ppm in the NMR spectra, indicating that the conformational equilibrium in the piperazine ring is rapid on the NMR timescale. The four equivalent carbon atoms of the piperazine ring resonate in the range 4648 ppm. A variable temperature NMR experiment suggests that there is restricted rotation around the N2N3 bond of the triazene moiety in 3. The NMR data compares favorably with previous reported data for 1-aryldiazenyl-4-methylpiperazines (1) and 1,4-di-(2-aryldiazen-1-yl)homopiperazines (2b).Key words: triazene, piperazine, diazonium coupling, NMR.
Palladium-catalyzed simple and efficient hydrogenative cleavage of azo compounds using recyclable polymer-supported formate
Authors: Abiraj Keelara , Srinivasa Gejjalagere R , Gowda D Channe
Published: May 2005

Palladium-catalyzed room temperature transfer hydrogenation of azo compounds using recyclable polymer-supported formate as the hydrogen donor produces corresponding amine(s) in excellent yields (88%98%). This method was found to be highly facile with selectivity over a number of other functional groups such as halogen, alkene, nitrile, carbonyl, amide, methoxy, and hydroxyl.Key words: azo compounds, catalytic transfer hydrogenation, polymer-supported formate, 10% Pd-C, amines.
29Si NMR studies on the mechanism of dehydrocoupling of hydrosilanes with hydroxylic reagents in DMF  The role of DMF
Authors: Chruściel Jerzy J
Published: May 2005

Interactions of DMF with hydrosilanes were studied by29Si NMR. New resonance signals were observed in the29Si NMR spectra of HMe2SiOSiMe2H and some (alkoxy)hydrosilanes for high ratios of concentrations [DMF]/[H-silane] at 25 °C. The intensities of new signals increased several times at 60 °C. It seems that these new resonances correspond to molecular complexes of DMF with hydrosilanes. The role of DMF in the mechanism of dehydrocoupling of hydrosilanes with hydroxylic reagents in the presence of Zn(II) and Cd(II) halides (X = Cl, Br, I) is discussed. Some common features of the reaction mechanism with the mechanism of hydride transfer from the SiH bond to the carbenium ion are discussed.Key words: hydrosilanes, hydroxylic reagents, reaction mechanism of dehydrocoupling in DMF,29Si NMR.
Theoretical study of the reaction of titanium ion with ethane  Structure, mechanism, and potential energy surface
Authors: Zhang Dongju , Fu Xuebing , Wang Ruoxi , Liu Chengbu
Published: May 2005

Density functional theory in its B3LYP variant has been used to study the reaction of Ti+ (4F) with ethane in the gas phase. The potential energy surface corresponding to [Ti, C2, H6]+, has been examined in detail at the B3LYP/6-311++G(3df,3pd)//B3LYP/6-311+G(d,p) level of theory. The quality of this theoretical method has been calibrated against the available thermochemical data. Three activation branches, CH, CC, and synchronous CH and CC bond activations, were proposed along the reaction coordinates, and two new mechanisms, the sequential 1,1-H2 elimination and the concerted elimination of CH4, were found.Key words: Ti+, ethane, reaction mechanism, potential energy surface, density functional theory.
The effect of prey availability on spider assemblages on European black pine (Pinus nigra) bark: spatial patterns and guild structure
Authors: Horváth Roland , Lengyel Szabolcs , Szinetár Csaba , Jakab László
Published: May 2005

Both habitat structural complexity and prey availability can influence the density and diversity of spider assemblages. We studied whether prey availability affects spider assemblages living on the bark of European black pine (Pinus nigra Arnold) in six localities in Hungary. We found both positive and negative relationships between spider and prey assemblages in a sample of 1290 spiders and 24 186 potential prey when among-locality variation in spider assemblages was controlled for. Species richness, number of individuals, and diversity of spiders increased with either the number of prey taxa or the number of prey individuals in a forest in western Hungary. Spider species richness and number of individuals increased with prey diversity but decreased with number of prey taxa in moderately air-polluted urban localities. There was a negative relationship between number of spider individuals and number of prey individuals in a heavily polluted urban locality. Numbers of nocturnal hunters but not diurnal hunters or web-builders increased with the number of their respective prey in the forest in western Hungary and in the moderately air-polluted urban localities. The number of exclusive bark-dwelling spiders increased with the number of prey individuals in forests in eastern Hungary and decreased with the number of prey individuals in the polluted urban locality. We suggest that patterns of spider assemblages can be influenced by prey availability and that other factors (e.g., habitat structural diversity and air pollution) also need to be considered in explaining these patterns.
Drift dives by male New Zealand fur seals (Arctocephalus forsteri)
Authors: Page Brad , McKenzie Jane , Hindell Mark A , Goldsworthy Simon D
Published: May 2005

Some phocid seal diving-behaviour studies have identified dives characterised by a period of passive drifting through the water column, rather than active locomotion. During these "drift dives" seals are thought to preferentially direct energy towards processing of food, lactate, or renal metabolites rather than to active propulsion. We describe the first drift dives reported in an otariid, the New Zealand fur seal (Arctocephalus forsteri (Lesson, 1828)), studied at Kangaroo Island in South Australia. Not all males in the study undertook drift dives and those that did were significantly heavier than those that did not, suggesting that body size may influence the propensity to drift dive in New Zealand fur seals. Drift dives lasted 6.0 ± 1.78 min and had passive drift segments of 3.5 ± 1.5 min, during which seals showed a negative change in depth (i.e., sinking) of 0.14 ± 0.05 m/s. Drift dives occurred at night and were possibly undertaken to avoid near-surface predators and to process food, lactate, or renal metabolites while resting.
Wolf response to two kinds of barriers in an agricultural habitat in Spain
Authors: Blanco Juan Carlos , Cortés Yolanda , Virgós Emilio
Published: May 2005

We examined the effect of two kinds of barriers on an expanding gray wolf, Canis lupus L., 1758, population in an agricultural habitat in north-central Spain. The barriers were (i) a four-lane fenced highway along a flat area without wildlife-crossing facilities, and (ii) the River Duero Artery (RDA), comprising the river itself (50–100 m wide) and several small infrastructures along it. From March 1997 to October 2001, all 4 radio-collared wolves living <15 km from the highway (1 adult territorial male, 1 territorial breeder female, 1 dispersing male, and 1 female in 3 periods of her life (territorial immature, disperser, and territorial breeder) crossed it on between 4% and 33% of 45–163 monitoring days via vehicle bridges. Moreover, 4 more highways that we monitored in areas without radio-collared wolves have not delayed expansion of the increasing wolf population, suggesting that these highways are not an important barrier for wolves in our study area. In contrast, only 3 of 8 wolves radio-collared <5 km from the RDA were detected crossing it, and 2 of those 3 started to cross it only after severe habitat disturbance; in addition, the RDA seems to have delayed wolf expansion for some 15 years, which suggests that it is a semipermeable barrier for wolves. We discuss the likely consequences of the RDA on the recovery of the Iberian wolf population.
Attraction of the land snail Anguispira alternata to fresh faeces of white-tailed deer: implications in the transmission of Parelaphostrongylus tenuis
Authors: Garvon Jason M , Bird Jacqueline
Published: May 2005

Terrestrial gastropods serving as intermediate hosts of Parelaphostrongylus tenuis (Dougherty, 1945) are infected either by crawling over infected faeces or by contact with larvae washed off faecal pellets onto surrounding soil. Some studies have concluded that gastropods avoid faeces; therefore, transmission must occur from soil. During two trials, Anguispira alternata (Say, 1816) were offered a choice of two types of larva-free (U) white-tailed deer (WTD; Odocoileus virginianus (Zimmermann, 1780)) faeces (trial 1) and a choice of larva-containing (L) or larva-free (U) WTD faeces (trial 2) in a laboratory setting. The snails were observed in proximity to U faeces 2.5 times more than expected in trial 1. They were found on faeces 3.4 times more than expected in trial 2, but showed a preference for U faeces, frequenting U faeces 3.1 times more than expected, while frequenting L faeces 1.7 times more than expected. In addition, we feel that this laboratory design could be a useful tool for further investigation of the epizootiology of P. tenuis in important intermediate host species.
Effect of glycoinositolphospholipids on the growth and differentiation ofTrypanosoma cruzisubpopulations
Authors: Carreira João Carlos Araujo , Thomaz Neide , Mello Cicero Brasileiro
Published: May 2005

We have analyzed the biological effects of glycoinositolphospholipids (GIPLs) derived from Trypanosoma cruzi Chagas, 1909 isolates (G-645 and C-48) on the behavior of clone Dm 28c and the Y strain during their extracellular development in vitro and in the invertebrate host Rhodnius prolixus Stål, 1859. In vitro, a direct correlation between the presence of GIPLs and proliferation of both Dm 28c and the Y strain was observed. The GIPLs purified from strain G-645 induced higher differences in the levels of growth of clone Dm 28c when compared with GIPLs purified from C-48 or Leptomonas samueli Carvalho, 1973. Differentiation in the presence of G-645 GIPLs was significantly reduced (48 h), while a minor effect was observed with GIPLs from C-48 (72 h). Parasites adhered preferentially to areas on slides coated with GIPLs from G-645 but not GIPLs from C-48. Rhodnius prolixus fed with GIPLs from G-645 or paraformaldehyde-fixed G-645 parasites, coincident with or after establishment of Dm 28c infection, presented different growth and differentiation patterns compared with control bugs. Our data suggest the occurrence of intraspecific cooperation and (or) competition among the different subpopulations that make up a specific T. cruzi strain.
Life-history patterns in female wild boars (Sus scrofa): mother–daughter postweaning associations
Authors: Kaminski G , Brandt S , Baubet E , Baudoin C
Published: May 2005

Mother–daughter postweaning associations in wild boars (Sus scrofa L., 1758) were investigated using 12 years' data from a wild population in Champagne, France. In the wild boar, a polygynous ungulate species, females (i) can reproduce as soon as they are yearlings and (ii) generally have large litters, in contrast to many other ungulate species. It is generally thought that their social organization is centered around groups of adult females and their offspring, but genealogical relationships in female groups have never been studied. Hence this species is suitable for testing the hypothesis of a matrilineal social organization. We studied the occurrence and strength of mother–daughter associations before and after the first potential breeding of yearling females, using a total of 85 individuals. Seasonal fluctuations in associations were observed, but after weaning, daughters generally remained with the mother. When leaving their natal group, yearling females formed new kin groups with sisters. Two important factors involved in the postweaning associations were adult and yearling reproductive participation and maternal age. The present study constitutes the first clear demonstration that family groups, with overlapping generations of females, represent the typical social organization in a forest wild boar population.
Identifying spiders through DNA barcodes
Authors: Barrett Rowan D.H , Hebert Paul D.N
Published: May 2005

With almost 40 000 species, the spiders provide important model systems for studies of sociality, mating systems, and sexual dimorphism. However, work on this group is regularly constrained by difficulties in species identification. DNA-based identification systems represent a promising approach to resolve this taxonomic impediment, but their efficacy has only been tested in a few groups. In this study, we demonstrate that sequence diversity in a standard segment of the mitochondrial gene coding for cytochrome c oxidase I (COI) is highly effective in discriminating spider species. A COI profile containing 168 spider species and 35 other arachnid species correctly assigned 100% of subsequently analyzed specimens to the appropriate species. In addition, we found no overlap between mean nucleotide divergences at the intra- and inter-specific levels. Our results establish the potential of COI as a rapid and accurate identification tool for biodiversity surveys of spiders.
Reply to the comment by L. Prendini on "Identifying spiders through DNA barcodes"
Authors: Hebert Paul D.N , Barrett Rowan D.H
Published: May 2005

Our paper on spiders provides an early demonstration of the power of DNA barcoding; we believe that its conclusions will prove scalable to all eukaryotes. We further anticipate that the "Barcode of Life" movement will soon lead to automated systems for species identification and discovery. However, we emphasize that these systems will operate within a Linnaean framework and that collaborations between molecular and morphological taxonomists are critical.
Locomotion is not influenced by denticle number in larvae of the fruit flyDrosophila melanogaster
Authors: Fitzpatrick Mark J , Szewczyk Evelyn
Published: May 2005

Denticles are small projections on the underside of larval fruit flies that are used to grip the substrate while crawling. Previous studies have shown that (i) there is natural variation in denticle number and pattern between Drosophila melanogaster (Meigen, 1830) and several closely related species and (ii) mutations affecting denticle morphology have negative effects on locomotory performance. We hypothesized that there would be a correlation between denticle number and locomotory performance within populations of D. melanogaster. Despite finding considerable variation in denticle number, we found no correlation between denticle number and three measurements of larval locomotion: speed, acceleration, and absolute turning rate.
Distribution and density of glochidia of the freshwater musselAnodonta kennerlyion fish hosts in lakes of the temperate rain forest of Vancouver Island
Authors: Martel André L , Lauzon-Guay Jean-Sébastien
Published: May 2005

We examined the distribution and abundance of glochidia of the freshwater mussel Anodonta kennerlyi Lea, 1860 on local fishes in three temperate rain forest lakes near Bamfield, on the west coast of Vancouver Island, British Columbia. Fishes involved in the life cycle of the mussel were the prickly sculpin (Cottus asper Richardson, 1836), threespine stickleback (Gasterosteus aculeatus L., 1758), Dolly Varden (Salvelinus malma (Walbaum, 1792)), and cutthroat trout (Oncorhynchus clarkii (Richardson, 1836)). For each lake, we assessed which fish was the most important for larval propagation and recruitment of the mussel by considering the fish's primary habitat, the percentage of fish in a sample with glochidia, and the abundance of glochidia on sampled fish. Also, an alternative method for quantifying the glochidia's "preference" for a host consisted of measuring the number of glochidia per unit area of fish body surface (larval density). We digitized the surface area of fins and head, i.e., the areas used by glochidia for settlement. Every fish species in each lake dispersed the glochidia. There was, however, a sharp gradient in the intensity of the fish–mussel linkage among fishes. Fishes that co-occurred most often with mussels, such as sculpins and sticklebacks, had the highest density of glochidia. Larval density on fishes also revealed the existence of between-lake differences in glochidia preference.
Mitochondrial introgression is restricted relative to nuclear markers in a water strider (Hemiptera: Gerridae) hybrid zone
Authors: Abe T A , Spence J R , Sperling F A.H
Published: May 2005

Although cytonuclear incompatibilities between species have been implicated in a variety of theoretical and experimental studies, the influence of such fitness interactions on gene introgression has been demonstrated in very few hybrid zones. We examined patterns of introgression between two species of Limnoporus Stål, 1868 water striders from 10 populations transecting a hybrid zone in Alberta and British Columbia. DNA-sequence variation in mitochondrial locus COI was compared with two nuclear loci, EF1-α and ITS 1. The spatial distribution of haplotype lineages showed strong barriers to gene exchange for mtDNA. Constraints on introgression were weaker for the nuclear markers, particularly ITS 1. The mtDNA from Limnoporus dissortis Drake and Harris, 1930 was associated with nuclear genes from Limnoporus notabilis Drake and Hottes, 1925 less often than expected by random mating, indicating that some cytoplasmic and nuclear combinations are favored over others and that cytonuclear incompatibilities play a role in structuring this hybrid zone. Mitochondrial mobility across the hybrid zone is likely to be restrained by the unusual hybrid inviability of these species. In a reversal of the pattern expected on the basis of Haldane's rule, females are the XX sex and yet hybrid females are much more inviable than males. Differential removal of hybrid females, which carry mtDNA, can explain disproportionately low mitochondrial introgression across the hybrid zone.
Plant-wax alkanes as seasonal markers of red deer dietary components
Authors: Bugalho Miguel N , Milne John A , Mayes Robert W , Rego Francisco C
Published: May 2005

n-Alkanes are long-chain hydrocarbons commonly occurring in plant cuticles that can be recovered in herbivore faeces. Differences among plant species in their content of cuticular wax n-alkanes can be exploited to estimate diet composition of herbivores. n-Alkanes have been used mainly in domesticated herbivores feeding on relatively simple diets over short-term periods. Extending the method to wild herbivores feeding on seasonal complex diets is possible provided that n-alkanes act as effective dietary component markers in different seasons. The n-alkane content of browse species and herbage layer and of faeces of red deer (Cervus elaphus L., 1758) males and females in a region with a Mediterranean climate is described. Information on the n-alkane content of plant species was related to that of faeces to estimate the diet composition of red deer. Plant species had distinct n-alkane contents, some of which varied seasonally. The n-alkane content of faeces also varied seasonally and between red deer sexes. Both red deer males and females had relatively high proportion of browse in their diets during summer and of herbage layer in spring, as shown by other studies in Mediterranean environments.
Population dynamics of the endangered mountain ecotype of woodland caribou (Rangifer tarandus caribou) in British Columbia, Canada
Authors: Wittmer Heiko U , McLellan Bruce N , Seip Dale R , Young James A , Kinley Trevor A , Watts Glen S , Hamilton Dennis
Published: May 2005

We used census results and radiotelemetry locations of >380 collared individuals sampled over the entire distribution of the endangered mountain ecotype of woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) in British Columbia, Canada, to delineate population structure and document the size and trend of the identified populations. We also describe the spatial pattern of decline and the causes and timing of adult mortality and provide estimates of vital rates necessary to develop a population viability analysis. Our results indicate that the abundance of mountain caribou in British Columbia is declining. We found adult female annual survival rates below annual survival rates commonly reported for large ungulates. The major proximate cause of population decline appears to be predation on adult caribou. Spatial patterns of population dynamics revealed a continuous range contraction and an increasing fragmentation of mountain caribou into smaller, isolated subpopulations. The population fragmentation process predominantly occurs at the outer boundaries of the current distribution. Our results indicate that recovery strategies for mountain caribou should be directed at factors contributing to the fragmentation and isolation of mountain caribou populations as well as management strategies aimed at increasing adult survival.
Experience levels of individuals in natural bee populations and their ecological implications
Authors: Dukas Reuven , Morse Douglass H , Myles Sean
Published: May 2005

Learning difficult tasks requires an extended period of experience. It is unclear, however, what level of experience is exhibited by individuals in natural populations. If many individuals are rather inexperienced at any given time, they may not possess subtle information concerning, for example, local distributions of reward and danger, which may require long acquisition periods. To quantify individual experience in field settings, we conducted a field study involving extensive marking of individual honey bees (Apis mellifera L., 1758) and bumble bees (Bombus vagans Smith, 1854 and Bombus terricola Kirby, 1837) visiting milkweed (Asclepias syriaca L.) patches that harbored crab spiders (Misumena vatia (Clerck, 1757)), which prey on bees. The vast majority of bees either were fully inexperienced or had little experience with the specific flower patch that they were visiting. It is likely that such inexperienced bees do not possess subtle local information involving either reward or danger. Contrary to our prediction, even the most experienced bees did not avoid experimental patches harboring crab spiders, perhaps because even these bees did not possess sufficient experience. Our results indicate that conclusions from controlled laboratory experiments may not readily generalize to natural field settings. Thus, we must gather additional data on the long-term behavior of individually marked bees in natural conditions to better understand the interactions among flowers, bees, and bees' predators.
ALMOST WORK-OPTIMAL PRAM EREW DECODERS OF LZ COMPRESSED TEXT
Authors: DE AGOSTINO SERGIO
Published: May 2005

We show nearly work-optimal parallel decoding algorithms which run on the PRAM EREW in O ( log n) time with O (n/( log n)1/2) processors for text compressed with LZ1 and LZ2 methods, where n is the length of the output string. We also present pseudo work-optimal PRAM EREW decoders for finite window compression and LZ2 compression requiring logarithmic time with O (dn) work, where d is the window size and the alphabet size respectively. Finally, we observe that PRAM EREW decoders requiring O ( log n) time and O (n/ log n) processors are possible with the non-conservative assumption that the computer word length is O ( log 2 n) bits.
ROUTING BALANCED COMMUNICATIONS ON HAMILTON DECOMPOSABLE NETWORKS
Authors: STACHO LADISLAV , ŠIRÁŇ JOZEF , ZHOU SANMING
Published: May 2005

In [10] the authors proved upper bounds for the arc-congestion and wave-length number of any permutation demand on a bidirected ring. In this note, we give generalizations of their results in two directions. The first one is that instead of considering only permutation demands we consider any balanced demand, and the second one is that instead of the ring network we consider any Hamilton decomposable network.

Thus, we obtain upper bounds (which are best possible in general) for the arc-congestion and wavelength number of any balanced demand on a Hamilton decomposable network. As a special case, we obtain upper bounds on arc- and edge-forwarding indices of Hamilton decomposable networks that are in many cases better than the known ones.
A SOLUTION TO THE THREE DISJOINT PATH PROBLEM ON HONEYCOMB TORI
Authors: YANG XIAOFAN , MENGSON GRAHAM M. , ZHANG SHAOMIN , LIU XIAOPING
Published: May 2005

In a previous paper we solved an open problem named as the three disjoint path problem on honeycomb meshes. In this paper we extend the technique used to solve the related problem on honeycomb tori. The result gives the minimum possible length of the longest of any three disjoint paths between two given nodes in a torus. The problem has practical benefits in the fault tolerant aspects of interconnection topologies.
GLOBAL OPTIMIZATION OF LINEAR HYBRID SYSTEMS WITH VARYING TIME EVENTS
Authors: LEE CHA KUN , BARTON PAUL I.
Published: May 2005

Dynamic optimization problems with linear hybrid (discrete/continuous) systems embedded whose transition times vary are inherently nonconvex. For a wide variety of applications, a certificate of global optimality is essential, but this cannot be obtained using conventional numerical methods. We present a deterministic framework for the solution of such problems in the continuous time domain. First, the control parametrization enhancing transform is used to transform the embedded dynamic system from a linear hybrid system with scaled discontinuities and varying transition times into a nonlinear hybrid system with stationary discontinuities and fixed transition times. Next, a recently developed convexity theory is applied to construct a convex relaxation of the original nonconvex problem. This allows the problem to be solved in a branch-and-bound framework that can guarantee the global solution within epsilon optimality in a finite number of iterations.
DEVICE-CENTRIC LOW-POWER SCHEDULING FOR REAL-TIME EMBEDDED SYSTEMS
Authors: HSIUNG PAO-ANN , KAO HSIN-CHIEH
Published: May 2005

Existing low power schedules mainly try to decrease overall system energy usage by shutting down unused devices after process scheduling. This often leads to suboptimal energy usage due to the lack of process slack time to shut down unused devices in a fixed system schedule such as that generated by a rate-monotonic or an earliest deadline first scheduler in a real-time embedded system. In this work, we try to integrate process scheduling with low power scheduling such that a low-power real-time feasible schedule is obtained. The proposed method called Low-Power Quasi-Dynamic Scheduling (LQS) was implemented and applied to some examples, including a sensor network node and Bluetooth devices, to prove its benefits.
A NEW MODEL FOR HETEROGENEOUS EMBEDDED SYSTEMS — What Esterel and SyncCharts Need to Become a Suitable Specification Platform
Authors: RADOJEVIC IVAN , SALCIC ZORAN , ROOP PARTHA
Published: May 2005

Specification of embedded systems based on formal models of computation is gaining importance. The behavior of an increasing number of embedded systems is heterogeneous, consisting of a mixture of control-dominated and data-dominated parts. While models of computations suitable to control-dominated systems and data-dominated systems are well developed, there are only a limited number of models catering to both systems. In this paper, we present informally a new model for heterogeneous embedded systems, called HEMOC, which combines three common models of computation, synchronous reactive, hierarchical finite state machines and synchronous data flow. Then, the languages Esterel and SyncCharts are used for system specification following the new model in order to determine what they need to become suitable specification platform.