bluuebunny/crossref_metadata_2025 huggingface dataset:
Reliability measures for buried flexible pipes
Authors: Sivakumar Babu G L , Rao Rajaparthy S
Published: May 2005

The safety of infrastructure facilities such as buried pipelines is the primary objective of engineering design. An improved measure of safety and reliability of these structures can be obtained with concepts of probability. The assessment of safety involves uncertainties at various stages, such as testing, design, and field installation and operations. This paper presents a reliability analysis to estimate the deflection (cross-sectional ovalization) and buckling response of buried flexible pipes, considering uncertainties in the design parameters. The need to consider variations in design parameters, such as soil modulus and bulk density of the fill, and the influence of correlation between soil modulus and bulk density in the estimation of reliability is emphasized. It was observed that reliability index decreases with an increase in the coefficient of variation of soil modulus and bulk density of the fill and increases with increase in correlation coefficient between the variables. It is possible to obtain a central factor of safety (CFS) value on the basis of the target reliability and variations in the design parameters. The use of reliability-based considerations is illustrated with two typical simple cases of buried pipe installations.Key words: reliability measures, buried flexible pipes, deflection (ovalization), buckling, variability, safety.
Model studies of a circular footing supported on geocell-reinforced clay
Authors: Sitharam T G , Sireesh S , Dash Sujit Kumar
Published: May 2005

The potential benefits of geocell reinforcement in soft clay foundations have been studied by a series of laboratory-scale static load tests on a rigid circular footing placed on a fill surface. Parameters of the test program include depth of placement of the geocell layer, width and height of the geocell layer, and influence of an additional layer of planar geogrid at the base of the geocell mattress. With the provision of geocell reinforcement, the load-carrying capacity of the soft clay foundation can be improved by a factor of up to 4.8 times that of the unreinforced soil. Heaving of the soil can be reduced substantially by providing geocell reinforcement of sufficient height and width. Further improvement in performance could be obtained with the provision of an additional layer of planar geogrid at the base of the geocell mattress.Key words: model study, circular footing, soft clay, geocell reinforcement, reinforced soil.
Numerical simulation of seismic cone signals
Authors: Howie John A , Amini Ali
Published: May 2005

Numerical analysis can provide insight into the effect of ground conditions on seismic signals recorded in downhole seismic testing. As part of a study of the interpretation of seismic cone data in complex ground conditions, this paper deals with the cases of wave propagation in (i) homogeneous soil and (ii) soil of increasing stiffness with depth. The main purpose of this study was to assess the validity of the use of the finite difference program FLAC for the simulation of the downhole seismic test. For realistic assumptions of material stiffness and damping, the main characteristics of field seismic cone penetration test (SCPT) seismic data were reproduced in the simulated data. Both displayed the same general shape of signal, number of oscillations, signal attenuation, frequency content, compression wave component (near-field effect), signal widening, and shift of the peak of the frequency spectrum with depth. Damping was shown to cause signal widening and dispersion, and the shear wave velocity, Vs, interpreted from the simulated wave traces varied with the interval method used to determine it. For a case history of field data, it was found that Vs varied by about 3%, depending on the analysis method used. The results show that finite difference modeling of wave propagation can provide useful insights into the factors affecting the interpretation of downhole seismic tests.Key words: seismic cone testing, shear wave velocity, signal widening, near-field effect, numerical simulation, finite difference.
Soil behaviour through field instrumentation
Authors: Oztoprak Sadik , Cinicioglu S Feyza
Published: May 2005

An improved version of the observational method is developed and proposed. The method uses field measurements as the direct inputs to the framework of the constitutive behaviour and analyses the behaviour synchronously as measurements are recorded. The method is developed for the specific case of embankments on soft clays, and its effectiveness is tested on a well-documented case history. The framework provided for the application of the method is basically the idealized stress space of the critical state theory, but the constitutive anisotropic elastoplastic soil model is added to this framework to analyse the behaviour and provide direct links between measurements and design parameters. Strain-rate dependency of the soft soils is also incorporated in the interpretation of the behaviour. To consider the variation in the behaviour of foundation soils, a zonation system is applied. Stress axis rotation is considered for active and passive regions effectively. Substantial savings can be achieved using the method in terms of time and cost, and the method is reliable. In addition, such an application improves the understanding of the real behaviour of soils.Key words: soft clays, embankment, observational method, rate effect, anisotropy, soil structure.
Thermodynamic properties of water in the water-poor region of binary water + alcohol mixtures
Authors: Liltorp Karin , Westh Peter , Koga Yoshikata
Published: May 2005

In our previous thermodynamic studies, we suggested that alcohol molecules in water-poor water + alcohol mixtures exist as alcohol clusters in a form similar to the pure alcohols. Here, we use calorimetry and densitometry to investigate how H2O interacts with alcohol clusters in water-poor binary aqueous mixtures of 12 different alcohols. The composition dependence of the measured excess partial molar enthalpy and volume of water (HEW and VEW), along with entropy data calculated from HEW and literature data for excess chemical potentials, showed that in water-poor solutions of small alcohols such as methanol, ethanol, and 1-propanol, mutual waterwater interactions are endothermic, but entropically favorable. Conversely, in long-chain solvents such as 1-octanol and 1-decanol, the interaction is exothermic and entropically unfavorable. We suggest that these observations reflect wateralcohol hydrogen bonding in short-chain solvents and water clustering with more hydrogen bonding than in pure water or "dewetting" in mixtures of the longer alcohols, respectively. The composition dependence of HEW was also used to locate anomalies that specify the boundary between the mixing schemes characterizing the intermediate and the water-poor regions of alcohol + water mixtures.Key words: aqueous alkane-mono-ols, excess partial molar enthalpy, entropy and volume, mixing schemes.
Synthesis and evaluation of 7-hydroxyindan-1-one-derived chiral auxiliaries
Authors: Narine Arun A , Wilson Peter D
Published: May 2005

A series of novel chiral acetals were prepared from 7-hydroxyindan-1-one and a variety of substituted chiral nonracemic C2-symmetric 1,2-ethanediols (R = Me, Ph, CH2OMe, CH2OBn, CH2O(1-Np), and i-Pr). These acetals were evaluated as chiral auxiliaries for use in asymmetric synthesis. A high degree of stereochemical induction was observed in the diethylaluminum chloride-promoted DielsAlder reaction of an acrylate derivative (R = i-Pr) with cyclopentadiene (91:9 dr). This demonstrated that these acetals could serve as effective chiral directors in asymmetric substrate-directed reactions.Key words: 7-hydroxyindan-1-one, chiral nonracemic C2-symmetric 1,2-diols, acetals, chiral auxiliaries, DielsAlder reaction.
Transition metal complexes of a sterically demanding diimine ligand
Authors: Masuda Jason D , Stephan Douglas W
Published: May 2005

The reaction of the metal halide with the sterically demanding ligand (i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2 afforded the complexes (i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2MX2 (X = Cl, M = Fe (2), Co (3); X = Br, M = Ni (4), M = Cu (5), Zn (6)). The species of 2 reacts with Li(OEt2)B(C6F5)4 to form the yellow adduct [(i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2Fe(µ-Cl)2Li(OEt2)2][B(C6F5)4] (7) while alkylation of 2 gave (i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2FeClCH2SiMe3 (8). The species [(i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2Ni(η3-C3H5)][B(3,5-CF3C6H3)4] (9) was obtained from reaction of 1 with [(η3-C3H5)NiBr]2 and [Na][B(3,5-(CF3)2C6H3)4] while reaction of 4 with Super-Hydride afforded (i-Pr2C6H3N)(C(Me)(NC6H3-i-Pr2))2NiH2BEt2 (10). X-ray data are reported for 210. The sterically demanding nature of the ligand inhibits subsequent reactivity of these species. Key words: sterically demanding ligands, chelate complexes, X-ray structure, diimine ligands.
Homoleptic magnesium bis-phosphinimide derivatives
Authors: Hollink Emily , Wei Pingrong , Stephan Douglas W
Published: May 2005

The homoleptic Mg-phosphinimide complexes Mg2(µ-NP-t-Bu3)2(NP-t-Bu3)2 (1) and Mg3(µ-NP-i-Pr3)4(NP-i-Pr3)2 (2) were obtained from the reaction of 2 equiv. of the phosphinimines HNPR3 (R = t-Bu, i-Pr) with MgBu2. Spectroscopic and crystallographic studies confirmed the dimeric and trimeric structures of compounds 1 and 2, respectively. Key words: magnesium, phosphinimides, homoleptic, crystal stuctures.
Synthesis and spectra of aldehyde- and ketone-O-(2,5-dihydro-2-methoxy-5,5-dimethyl-1,3,4-oxadiazol-2-yl)oximes  Thermal sources of some methoxy(oximino)carbenes
Authors: Klys Arkadiusz , Dawid Malgorzata , Warkentin John
Published: May 2005

Ten new oxadiazoline sources of methoxy(oximino)carbenes were synthesized by exchanging the acetoxy group of 2-acetoxy-2-methoxy-Δ3-1,3,4-oxadiazoline with an oximino group. The new compounds were characterized by means of spectroscopy and the formation of carbenes upon thermolysis of a few was demonstrated by means of interception with tert-butyl alcohol. The carbenes fragmented to form methoxycarbonyl and iminyl radicals.Key words: 2,2-dioxyoxadiazoline, methoxy(oximino)carbene, oxadiazole, radical pair, rearrangement.
Oxo-rhenium(V) complexes with 8-hydroxyquinoline derivatives
Authors: Sigouin Olivier , Beauchamp André L
Published: May 2005

Compounds of the types ReOCl2(L)(PPh3) and ReOCl(L)2 were prepared by reacting ReOCl3(PPh3)2 with 8-hydroxyquinoline (HL) and its 2-methyl, 2-chloro, 5-chloro, 5-nitro, 5,7-dichloro, 5,7-dibromo, and 5,7-diiodo derivatives. With the bulky 2-phenyl-8-hydroxyquinoline, only ReOCl2(L)(PPh3) could be isolated, whereas the still bulkier 2-tert-butyl derivative did not react. For ReOCl2(L)(PPh3), the coordination of the quinoline oxygen trans to the Re=O bond and the cis-dichloro arrangement in the equatorial plane were established from crystallographic studies on the 2-chloro and the 5,7-dibromo complexes. From the combined data for these various derivatives, the 1H NMR signals could be fully assigned. With both series of compounds, a complex dd absorption pattern is observed in the visible spectra, corresponding to the excitation of a d electron from the interaxial d orbital in the equatorial plane to the empty dxz and dyz orbitals, which are inequivalent in these low-symmetry systems. Deconvolution revealed the presence of two very weak low-energy components (~10 000 and ~12 000 cm1), which are assigned to the two expected singlettriplet transitions, whereas two stronger bands at higher energy (~14 000 and ~17 000 cm1) originate from the two singletsinglet transitions. These bands are not substantially displaced by substitution on the 8-hydroxyquinoline rings.Key words: rhenium, quinoline, crystal structure, dd electron transitions.
Lanthanide complexes of an oxazoline-phenoxide hybrid chelate
Authors: Berg David J , Zhou Chuanjian , Barclay Tosha , Fei Xuening , Feng Shengyu , Ogilvie Kevin A , Gossage Robert A , Twamley Brendan , Wood Mark
Published: May 2005

The synthesis of 2-(2′-hydroxy-3′-allylphenyl)-4,4-dimethyl-2-oxazoline, H-Allox (3), and lanthanide tris chelate complexes, mer-Ln(Allox)3 (Ln = La (4), Ce (5), Sm (6), Er (7), and Y (8)), derived from it are reported. A six-coordinate mer geometry without alkene coordination was confirmed in the solid state by X-ray crystallography for 5 and 7. Variable-temperature NMR experiments suggested that this is the most stable isomer in solution as well, although the inequivalent ligand environments undergo rapid averaging at room temperature for all five complexes. A mechanistic investigation indicated that this fluxional process is an intramolecular six-coordinate rearrangement, but it was not possible to distinguish between a Bailar (trigonal) or RâyDutt (rhombic) twist. Kinetic parameters for the fluxional process were determined by line shape analysis for 8 yielding ΔH = 24 ± 2 kJ mol1 and ΔS = 99 ± 10 J mol1 K1. The structural and dynamic features of 48 were compared with the related In, Ga, and Al tris(2-oxazolylphenoxides).Key words: oxazoline, phenoxide, lanthanide, Group 3, RâyDutt twist, Bailar twist, Eyring plot, X-ray crystallography, mer isomer, variable-temperature NMR, line shape analysis, dynamic NMR, paramagnetic NMR, bidentate ligands.
On the synthesis of new amphiphilic entities by the succinic coupling of β-cyclodextrins to calixarenes
Authors: Jankowski Christopher K , Arseneau Sébastien , Blu Jérome , Mauclaire Laurent , Aychet Nicolas
Published: May 2005

Novel molecules, composed of a β-cyclodextrin coupled via a succinic diamide linker to di-n-octyl-calix[4]arene monocrown-6 or to biscrown-6-calix[4]arene, were synthesized by two independent routes: from mono-6′-deoxy-6′-amino-β-cyclodextrin, and from tetraaminocalix[4]arene derivatives. Key words: β-cyclodextrincalix[4]arene coupling, aminosuccinate-β-CD, aminosuccinate-calix[4]arene, octyloxy-calix[4]arenemonocrown-6, calix[4]arenebiscrown-6.
Viscosities of some tetraalkylammonium bromides in 2-ethoxyethanol at 308.15, 313.15, 318.15, and 323.15 K
Authors: Haldar Purushottam , Das Bijan
Published: May 2005

The viscosities of the solutions of tetraethylammonium bromide (Et4NBr), tetrapropylammonium bromide (Pr4NBr), tetrabutylammonium bromide (Bu4NBr), tetrapentylammonium bromide (Pen4NBr), and tetraheptylammonium bromide (Hep4NBr) in 2-ethoxyethanol have been reported at 308.15, 313.15, 318.15, and 323.15 K. The viscosity data have been analyzed by the JonesDole equation for the associated electrolytes to evaluate the viscosity B coefficients of the electrolytes. These data have also been analyzed by the transition-state treatment to obtain the contribution of the solutes to the free energy of activation for viscous flow of the solution. The viscosity of the solvent is found to be greatly modified by the presence of all of the tetraalkylammonium ions investigated. Moreover, the tetraalkylammonium ions are found to be unsolvated in 2-ethoxyethanol solutions, they behave neither as structure-breaker nor as structure-maker and the formation of the transition state is made less favorable in their presence.Key words: viscosity, electrolytes, tetraalkylammonium ion, 2-ethoxyethanol, ionic contribution, solvation, transition-state treatment.
Predatory behaviour and prey-capture decision-making by the web-weaving spider Micrathena sagittata
Authors: Díaz-Fleischer Francisco
Published: May 2005

Optimal-foraging theory predicts how a predator would feed most efficiently when faced with a choice of two types of prey differing in profitability and density in the habitat. The predator should focus only on the more profitable prey, since any prey item eaten by the predator has a cost in terms of the time and resources taken to subdue and eat it. A study of the hunting behaviour and prey-type selection of the web-weaving spider Micrathena sagittata (Walckenaer, 1841) (Araneae: Araneidae) in the field is documented. In the first part of the study, prey of two sizes were offered in four sectors of the web (top, bottom, right, and left). A prey item was provided at one position of the web at a time. Attack time was recorded at each position. Also, choice and no-choice tests were carried out by offering prey in opposing web sectors (top and bottom) simultaneously. Large prey were more successfully captured in the upper parts than in the bottom parts of the web. In the choice test, spiders always preferred large prey to small prey, while in the no-choice test, spiders always responded to the first stimulus received. Two different attack strategies, depending on prey size, were observed. Hunting strategies and prey-size preference can be related to the cost of web construction and profitability of the prey type.
Factors influencing the diving behaviour of fish-eating killer whales: sex differences and diel and interannual variation in diving rates
Authors: Baird Robin W , Hanson M Bradley , Dill Lawrence M
Published: May 2005

Diving behaviour of air-breathing vertebrates may be influenced by a variety of factors including age, body size, and changes in prey behaviour and (or) abundance over both short and long timescales. We studied the diving behaviour of a highly sexually dimorphic odontocete cetacean, the killer whale, Orcinus orca (L., 1758), using suction-cup-attached time-depth recorders (TDRs). We tested the hypotheses that dive rates (no. of dives/h greater than or equal to specific depths) of fish-eating killer whales varied between males and females, with age, between day and night, and among pods and years. Data were used from 34 TDR deployments between 1993 and 2002 in the inshore waters of southern British Columbia, Canada, and Washington, USA. Dive rates did not change with age or differ among pods or between males and females, although analyses restricted to adults showed that adult males dove deep significantly more frequently than adult females during the day. For all whales, dive rates and swim speeds were greater during the day than at night, suggesting decreased activity levels at night. Dive rates to deeper depths during the day decreased over the study, suggesting a long-term change in prey behaviour or abundance, though uncertainty regarding the diet of this population precludes determination of the cause of such changes.
Ontogenetic changes in the visual acuity ofSepia officinalismeasured using the optomotor response
Authors: Groeger G , Cotton P A , Williamson R
Published: May 2005

For many organisms vision is of fundamental importance to many aspects of their lives. Here we present the first study to examine the effects of ontogeny and light intensity on the vision of a cephalopod. We measured the visual acuity of four size classes of Sepia officinalis L., 1758 (common cuttlefish) under four light intensities. We used an optomotor testing system in which we recorded the unconditioned whole-body movements exhibited by individuals when placed inside a rotating cylinder lined with vertical black and white stripes. By varying the width of these stripes to determine the minimum width associated with a positive response, we were able to estimate the visual acuity angle or minimum separable angle (MSA). We found a significant effect of both body size and light intensity; larger animals had greater visual acuity, while individuals of all size classes discriminated more detail at higher light intensities. The minimum recorded MSA for S. officinalis was 34' of arc (0.57°) for the largest animals (80 mm) at the highest light intensity used (15 µW·cm–2). Decreasing light intensity from 15 to 4.5 µW·cm–2affected animals of all sizes to approximately the same degree, reducing their visual acuity by approximately 55%.
Effects of surface activity patterns and dive depth on thermal substitution in fasted and fed lesser scaup (Aythya affinis) ducks
Authors: Kaseloo Paul A , Lovvorn James R
Published: May 2005

High thermoregulation costs incurred by aquatic endotherms can be reduced if heat from digestion and exercising muscles can substitute for thermogenesis. Costs (VO2) of surface activities and diving were measured in lesser scaup (Aythya affinis (Eyton, 1838)) ducks while fasted and when feeding on mixed grain at depths of 1.2 and 2 m at thermoneutral (23 °C) and sub-thermoneutral (8 °C) water temperatures. Substitution occurred if the heat increment of feeding (HIF) or costs of activities above resting metabolic rate (RMR) were lower at 8 °C than at 23 °C, indicating that the thermoregulatory part of RMR at 8 °C had been reduced. Changes in body core temperature were not significant, and there was no substitution of HIF. At the surface at 8 °C, fasted birds that were active (nonresting) >75% of the time had lower RMR, and lower cost of activities above RMR, than less active birds. Dive recovery cost after dive bouts (DRC) constituted 33%–35% of total dive costs at 23 °C and 48%–55% at 8 °C. Dive costs above RMR (including DRC) were lower at 8 °C than at 23 °C by 14% at 1.2 m and 25% at 2 m, suggesting appreciable substitution that increased with longer, deeper dives; however, results varied widely and were not statistically significant. Our experiments indicate that thermal substitution varies in importance depending on levels of activity and heat loss.
Why is group size correlated with the size of the host sea anemone in the false clown anemonefish?
Authors: Mitchell Jeremy S , Dill Lawrence M
Published: May 2005

When social groups monopolize discrete habitat patches, group size may be positively correlated with patch size. The correlation can be a direct consequence of limited resources. Alternatively, it can be an indirect consequence of patch-size effects on a dominant group member. We asked which of these two mechanisms was responsible for a positive correlation between the group size of false clown anemonefish (Amphiprion ocellaris Cuvier in Cuvier and Valenciennes, 1830) and that of the host sea anemone Stichodactyla gigantea (Forskål, 1775). We argue that some false clown anemonefish groups may have reached the carrying capacities of their hosts, but that the group size : patch size correlation in the population as a whole is best interpreted as an indirect consequence of a positive relationship between anemone size and the length of the dominant group member. The dominant's length in turn limits group size because dominant group members inhibit the growth of their subordinates. Thus, a correlation between group size and patch size need not imply resource limitation of subordinate group members.
Yellow-bellied marmot hiding time is sensitive to variation in costs
Authors: Blumstein Daniel T , Pelletier David
Published: May 2005

Many species use refugia to avoid predators, but remaining in a refuge is costly because foraging and engaging in other beneficial activities are curtailed while in a refuge. Thus, we expect that the duration of refuge use will be optimized. We tested a key prediction of this optimization hypothesis in yellow-bellied marmots, Marmota flaviventris (Audubon and Bachman, 1841), by providing supplemental food next to their burrows to manipulate the costs of remaining in a refuge. We then systematically walked towards a subject that was foraging on supplementary food or a subject that was not foraging on supplementary food until the individual disappeared into its burrow. We found a significant effect of our feeding treatment; subjects with supplementary food emerged from their burrows sooner than those without it. We also found a complex interaction between our feeding treatment and immergence distance (i.e., the distance subjects were at when they disappeared into their burrows). Individuals that tolerated close approaches emerged sooner when food was present, while those that were intolerant of approaching humans took longer to emerge and emerged sooner when food was not present. Juveniles emerged significantly sooner than adults, while there was no detectable difference between emergence times for adults and yearlings. This is the first demonstration in a mammal that hiding time is sensitive to the cost of remaining in the burrow. A number of previous studies on hiding times have focused on ectothermic species. More generally, our results suggest that endotherms are also likely to optimize the time that they remain in a refuge.
Blubber fatty acids of gray seals reveal sex differences in the diet of a size-dimorphic marine carnivore
Authors: Beck Carrie A , Iverson Sara J , Bowen W Don
Published: May 2005

Sex differences in foraging behaviour have been attributed to size dimorphism, niche divergence, and sex-specific fitness-maximizing strategies. Although sex differences in diving behaviour of marine carnivores are thought to result in sex differences in diet, this is not known for any species over temporal scales relevant to life-history characteristics. We examined blubber fatty acid (FA) profiles of gray seals, Halichoerus grypus (Fabricius, 1791), a sexually size-dimorphic species in which sex differences in foraging behaviour have been observed. FA profiles reflect prey consumed over a period of weeks or months. FA profiles of adult males and females varied significantly by season but there was a season by sex interaction, indicating that seasonal changes in diet differed by sex. FA profiles of adults also varied interannually, with a significant sex by year interaction. Interannual variability may have been a response to changes in ocean-bottom temperatures affecting prey availability or changes in prey abundance. Adult FA profiles differed from those of 6-month-old juveniles; however, there was no evidence of sex differences in the diet of younger animals. Our results indicate that sex differences in the foraging behaviour of adults are reflected in differences in diet at multiple temporal scales.
Do carotenoids and spleen size vary with helminth load in greylag geese?
Authors: Figuerola Jordi , Torres Jordi , Garrido Juan , Green Andy J , Negro Juan Jose
Published: May 2005

It has been suggested that carotenoid-derived coloration serves as an indicator of parasite levels and (or) the general health of birds. We investigated relationships among spleen size (sometimes considered an indicator of the cellular immune response capacity of birds), carotenoid level, helminth load, and leg and bill coloration of greylag geese, Anser anser (L., 1758), from Doñana National Park (southwest Spain). Nematode abundance was positively related to spleen size and negatively to body condition, but only in males. Coloration of bill and legs was a reliable indicator of cestode but not nematode abundance. Individuals with many cestodes had greater carotenoid stores, suggesting that helminths do not limit carotenoid absorption. Rather, it suggests either that parasitized geese were accumulating more carotenoids to control parasite-induced damage, or that carotenoid-rich diets expose geese to more intermediate hosts of cestodes. Our results support the role of integumentary carotenoid-derived coloration as an indicator of parasitism, but only for particular taxonomic groups.
A chaetotaxy for cephalic sensilla in larval Simuliidae (Diptera)
Authors: Craig Douglas A
Published: May 2005

To develop a chaetotaxy for heads of larval Simuliidae (Diptera: Culicomorpha), position of head sensilla relative to other structures, plus sensillar innervation, were used to establish homologies with head sensilla of larval mosquitoes (Culicidae). Cleared whole mounts of first- and later-instar larval simuliids were examined using light microscopy. Histological sections were used to determine innervation, as was in vivo methylene blue staining. First-instar larval simuliids have 18 primary sensillar pairs that allow homologies with sensilla of later-instar larval culicids to be established. These homologies can be tracked in later-instar larval simuliids even though numerous secondary sensilla are present and positions of primary sensilla change. Homologies could not be determined for antennal sensilla of larval simuliids. Innervation of cephalic sensilla from the brain is in agreement with embryological origin of the various head regions. Innervation patterns of cephalic sensilla appear conserved in culicomorphs and it is proposed that, when possible, sensillar innervation be used to establish chaetotaxies.
Landscape resistance to frog movements
Authors: Mazerolle M J , Desrochers A
Published: May 2005

An animal's capacity to recolonize a patch depends on at least two components: its ability to detect the patch and its ability to reach it. However, the disruption of such processes by anthropic disturbances could explain low animal abundance patterns observed by many investigators in certain landscapes. Through field experiments, we compared the orientation and homing success of northern green frogs (Rana clamitans melanota Rafinesque, 1820) and northern leopard frogs (Rana pipiens Schreber, 1782) translocated across disturbed or undisturbed surfaces. We also monitored the path selected by individuals when presented with a choice between a short distance over a disturbed surface and a longer, undisturbed route. Finally, we measured the water loss and behaviour of frogs on substrates resulting from anthropogenic disturbances and a control. When presented with a choice, 72% of the frogs avoided disturbed surfaces. Although able to orient towards the pond of capture when translocated on disturbed surfaces, frogs had a lower probability of homing successfully to the pond than when translocated at a similar distance on an undisturbed surface. Frogs lost the most water on substrates associated with disturbance and in the absence of cover. Our data illustrate that anthropically disturbed areas devoid of cover, such as mined peatlands and agricultural fields, disrupt the ability of frogs to reach habitat patches and are likely explanations to their reduced abundance patterns in such environments.
Geographic variation, genetic structure, and conservation unit designation in the Larch Mountain salamander (Plethodon larselli)
Authors: Wagner R Steven , Miller Mark P , Crisafulli Charles M , Haig Susan M
Published: May 2005

The Larch Mountain salamander (Plethodon larselli Burns, 1954) is an endemic species in the Pacific northwestern United States facing threats related to habitat destruction. To facilitate development of conservation strategies, we used DNA sequences and RAPDs (random amplified polymorphic DNA) to examine differences among populations of this species. Phylogenetic analyses of cytochrome b revealed a clade of haplotypes from populations north of the Columbia River derived from a clade containing haplotypes from the river's southwestern region. Haplotypes from southeastern populations formed a separate clade. Nucleotide diversity was reduced in northern populations relative to southern populations. These results were corroborated by analyses of RAPD loci, which revealed similar patterns of clustering and diversity. Network analyses suggested that northern populations were colonized following a range expansion mediated by individuals from populations located southwest of the river. Changes in the Columbia River's location during the Pliocene and Pleistocene likely released distributional constraints on this species, permitting their northern range expansion. Based on the barrier presented by the Columbia River's present location and differences in haplotype diversity and population structure observed between northern and southern populations, we suggest that designation of separate management units encompassing each region may assist with mitigating different threats to this species.
Cardiovascular adjustments during locomotion in penguins
Authors: Green Jonathan , Woakes Anthony , Boyd Ian , Butler Patrick
Published: May 2005

The high costs of airborne flapping flight are reflected in a difference between the oxygen pulse (OP; amount of oxygen consumed per heart beat) during flight and that during terrestrial locomotion, as well as a difference in the relationship between heart rate (fH) and rate of oxygen consumption ([Formula: see text]O2). We tested and failed to accept the hypothesis that there would be similar differences in the fH–[Formula: see text]O2and [Formula: see text]O2–OP relationships during swimming under water and during walking for macaroni penguins (Eudyptes chrysolophus (Brandt, 1837)). We suggest that this may be a result of the penguins having to overcome physical forces different from those experienced by volant birds and possibly a response to limited access to oxygen while porpoising or diving. This result has important implications for those who wish to use fHto estimate [Formula: see text]O2and hence metabolic rate in the field for this and similar species. To test the utility of the relationship, we compared our results with data obtained previously for this species, and we simultaneously measured [Formula: see text]O2in a respirometer and estimated [Formula: see text]O2from fHfor 48 h. There was no significant difference in the fH–[Formula: see text]O2or [Formula: see text]O2–OP relationships between the two studies or between [Formula: see text]O2estimated from fHand that measured using respirometry.
THE NEED FOR ADAPTIVE DYNAMIC THREAD SCHEDULING IN SIMULTANEOUS MULTITHREADING
Authors: SHIN CHULHO , LEE SEONG-WON , GAUDIOT JEAN-LUC
Published: May 2005

Earlier studies on Simultaneous Multithreaded (SMT) architectures showed that performance of a realistic SMT architecture saturates early. This paper addresses our contention that a fixed hardware thread scheduling strategy cannot provide optimal results for various thread combinations. We propose an approach that partially schedules threads in the form of a detector thread at a nominal hardware and software cost. It offers the capability to adaptively switch thread scheduling policies depending on various situations. This article shows that there is much room for performance improvement for our adaptive dynamic thread scheduling approach. The results we have obtained by simulating a realistic SMT architecture show that no single fetch policy may outperform the rest more than 50% of the total time. We show that 27% is approximately the upper-bound of the performance improvement for SMT with eight contexts. This demonstrates that our approach may significantly improve performance with good low-throughput detection and fetch policy selection heuristics.
The Systolic Reconfigurable Mesh
Authors: ESHAGHIAN-WILNER MARY M. , MILLER RUSS
Published: May 2005

In this paper, we introduce the Systolic Reconfigurable Mesh (SRM), which combines aspects of the reconfigurable mesh with that of systolic arrays. Every processor controls a local switch that can be reconfigured during every clock cycle in order to control the physical connections between its four bi-directional bus lines. Data is input on one side of the systolic reconfigurable mesh and output from another side, one row/column per unit time. Efficient algorithms are presented for intermediate-level vision tasks, including histograming, connectivity, convexity, and proximity.
IMPROVED BOUNDS ON CUTWIDTHS OF SHUFFLE-EXCHANGE AND DE BRUIJN GRAPHS
Authors: MONIEN BURKHARD , VRŤO IMRICH
Published: May 2005

We prove that the cutwidth of the n-dimensional shuffle-exchange graph is at most ⌈2n+1/n⌉, for n≥10. This essentially improves on the previous best constant factors. As a consequence we obtain an improved upper bound for the cutwidth of the de Bruijn graph.
OPTIMAL EMBEDDING OF HONEYCOMB NETWORKS INTO HYPERCUBES
Authors: BEIN DOINA , BEIN WOLFGANG W. , BRAJKOVSKA NATASA , LATIFI SHAHRAM
Published: May 2005

We present an optimal embedding of a honeycomb network (honeycomb mesh and honeycomb torus) of size n into a hypercube with expansion ratio of [Formula: see text] when n is a power of two. When n is not a power of two, the expansion is [Formula: see text], which we conjecture to be near optimal. For a honeycomb mesh, the dilation of the embedding is 1. For a honeycomb torus, the dilation can be as large as 2⌈ log n⌉+3, because of the extra links connecting symmetric opposite nodes of degree two. A honeycomb network, built recursively using hexagon tessellation, is a multiprocessor interconnection network, and also a Cayley graph, and it is better than the planar mesh with the same number of nodes in terms of degree, diameter, number of links, and bisection width.
DISTANCE-TWO INFORMATION IN SELF-STABILIZING ALGORITHMS
Authors: GAIRING MARTIN , GODDARD WAYNE , HEDETNIEMI STEPHEN T. , KRISTIANSEN PETTER , McRAE ALICE A.
Published: May 2005

In the state-based self-stabilizing algorithmic paradigm for distributed computing, each node has only a local view of the system (seeing its neighbors' states), yet in a finite amount of time the system converges to a global state satisfying some desired property. In this paper we introduce a general mechanism that allows a node to act only on correct distance-two knowledge, provided there are IDs. We then apply the mechanism to graph problems in the areas of coloring and domination. For example, we obtain an algorithm for maximal 2-packing which is guaranteed to stabilize in polynomial moves under a central daemon.
A SOLUTION TO THE THREE DISJOINT PATH PROBLEM ON HONEYCOMB MESHES
Authors: YANG XIAOFAN , MEGSON GRAHAM M. , ZHANG SHAOMlN , LIU XIAOPING
Published: May 2005

Recently honeycomb meshes have been considered as alternative candidates for interconnection networks in parallel and distributed computer systems. This paper presents a solution to one of the open problems about honeycomb meshes—the so-called three disjoint path problem. The problem requires minimizing the length of the longest of any three disjoint paths between 3-degree nodes. This solution provides information on the re-routing of traffic along the network in the presence of faults.
EFFICIENT STATE-SAVING ARCHITECTURES FOR POWER-MODE SWITCHING
Authors: PADMANABHAN SANDEEP , LEE YANN-HANG
Published: May 2005

Time and energy is expended in switching between power modes (e.g., active, hibernate, sleep, etc.). Powering off cache is one major reason for this. When there is a switch in the power-mode involving cache power-off, the system spends time and energy in filling the cache with new data (inherent cache misses). In our technique, before powering off the cache, we save its state in Embedded DRAM and bring it back when the previous power mode is restored. Our experiments have showed that in a majority of cases the cache contents are too valuable to be erased. By saving the contents we can reduce switching speed and energy. We present a heuristic to save the most relevant cache contents so that power and delay overheads are minimized. To measure the area overhead a synthesizable VHDL model was designed.
EXTENDABLE AND DYNAMICALLY RECONFIGURABLE MULTI-PROTOCOL FIREWALL
Authors: LY SUNG , BIGDELI ABBAS
Published: May 2005

Security issues within a networking environment are critical, as attacks or intrusions can come from many different sources. Firewalls are an effective tool used for intrusion detection and provide protection against attacks on a system or network. In the past, protection barriers for a local network have been provided using software solutions. Emerging multi-gigabit networking technology and the high uptake of gigabit Ethernet has rendered these solutions inefficient as it cannot cope with the high data rate. In this paper, a new approach using reconfigurable hardware such as Field Programmable Gate Arrays is proposed to provide the flexibility and performance required for a gigabit firewall. The solution is extendable, has low cost and is capable of scanning multiple protocols. The design approach will allow it to be easily ported over to another family of chips with no or minor modification.
CONTROL-ORIENTED MODELING OF 2D TORSIONAL MICROMIRROR
Authors: ZHAO YI , TAY FRANCIS E. H. , FOOK SIONG CHAU , ZHOU GUANGYA
Published: May 2005

This paper presents a simplified model of 2D torsional micromirror for control design. The micromirror system is modeled as a two inputs two outputs (TITO) system with nonlinear electrostatic torques, which are coupled with the two inputs and the two tilt angles. The coupling property of the electrostatic torques makes it difficult to design the control law. To surmount the problem, a new model based on extracting the dominant nonlinear terms and Taylor's expansion is proposed. The micromirror system together with the simplified model is coded in Matlab™ S-function. The simulation result shows that the model is feasible for control design.
A REACHABILITY-BASED TECHNIQUE FOR IDLE SPEED CONTROL SYNTHESIS
Authors: DANG THAO
Published: May 2005

The goal of this paper is to demonstrate the application of the algorithmic analysis of hybrid systems to idle speed control. This problem can be formulated as to design a safety hybrid controller. In principle, such controllers can be derived from the maximal invariant set. It is, however, hard to compute this set for a nonlinear hybrid system with both continuous control and disturbance inputs. We propose to use a class of piecewise constant control functions, which allows to develop an effective synthesis algorithm based on reachability computations. In addition, we show how assume-guarantee reasoning from automatic verification can be used to reduce the computational complexity.
HW/SW CO-DESIGN FOR LOW POWER ARITHMETIC AND LOGIC UNITS
Authors: TAY TENG TIOW , NG KAR SIN , PAN YAN
Published: May 2005

As many embedded microprocessors are battery driven, low power design is becoming increasingly necessary. In this paper, we proposed hardware-software co-design architecture for low power arithmetic and logic units. By including multiple functional units with the same functions and different speeds, we provide instruction implementations at various power prices. Then, with an assembler level scheduler, we identify and create situations whereby the low-power slow functional units can be utilized. The overall performance is not compromised as no additional stalls are introduced. Simulations show 10%~35% power saving in typical addition operations.
AN EVOLVABLE OPERATING SYSTEM FOR WIRELESS SENSOR NETWORKS
Authors: DO THU-THUY , KIM DAEYOUNG , LOPEZ TOMAS SANCHEZ , KIM HYUNHAK , HONG SEONGKI , PHAM MINH-LONG , LEE KWANGYONG , PARK SEONGMIN
Published: May 2005

With low-power consumption, small code and data size, evolvability as design criteria, we develop an evolvable operating system (EOS) for wireless sensor network applications. The EOS provides memory space efficient thread management, collaborative thread communication model and network stack. It also supports power management of microcontroller and radio transceiver, and network wide time synchronization function. Above all, the most important feature is the concept of evolvability with which the operating system itself can be easily configurable and upgradeable.
A NEW APPROACH IN DESIGNING INTERPROCESS COMMUNICATION FOR REAL-TIME SYSTEMS
Authors: HUGHES LARRY , MARZI HOSEIN , LIN YANTING
Published: May 2005

In networked and distributed environments, and in multi-tasking systems, processes run simultaneously and compete to access the system resources. Processes commonly communicate with one another. Various techniques have been adapted in designing Interprocess Communication mechanisms within operating systems such as signals and message-passing. Signals are software interrupts notifying a process that an event has occurred; they do not support data exchange between processes. Message-Passing, a widely used technique in this design, it may use pipes to allow two or more processes to exchange data. Current techniques degrade performance of Real-time Systems, where unmet time critical missions may result in catastrophic failure. This research introduces a library-based architecture for Interprocess Communication Systems (IPC). This technique supports real-time performance and can be adapted for embedded operating systems. Improved Real-time performance was achieved by running IPC as a set of library function and verified by testing on real-time embedded system.
THE DEVELOPMENT OF AN EMBEDDED, INTEGRATED INS/GPS SYSTEM
Authors: JIANG T. Y. , GUZMAN J. , LI H. Z. , GONG Z. M.
Published: May 2005

An embedded, real-time, loosely-coupled INS/GPS integration system has been developed and used for an unmanned land vehicle's control and navigation. For this integrated system, a Kalman filter software is used for INS error damping and corrections via the weighted aiding of a GPS output. The detailed development work will be presented in this paper including algorithm simplification, sensor selection and critical problems solving. Vehicular trial is also conducted. Simulated outage in GPS availability is made to assess the bridging accuracy of this system.
THE RAPID DEVELOPMENT OF A CLOSED-LOOP CONTROL SYSTEM
Authors: DING ZHONG-QIANG , LING KECK VOON , GOH KIAH MOK
Published: May 2005

In this paper, the methods to rapidly deploy closed-loop control systems are presented. A flexible real-time embedded platform based on reconfigurable computing technologies is established, on which control blocks consisting of optimized control algorithms are set up. By employing control blocks, a set of tools aiming to shorten the development cycle of embedded control systems are developed. Compare to conventional ways, the tools give controller developers much faster ways to construct required controllers with higher flexibility.
FORMAL DESIGNS FOR EMBEDDED AND HYBRID SYSTEMS
Authors: DONG JIN SONG , HAO PING , MAHONY BRENDAN
Published: May 2005

The design of embedded and hybrid systems requires powerful mechanisms for modeling data, state, concurrency and real-time behaviour. The {first} part of this paper illustrates a powerful design notation Timed Communicating Object Z (TCOZ) that has both channel based and sensor/actuator based interfaces. We believe that TCOZ is well suited for presenting more complete and coherent design models for complex embedded and hybrid systems. However, the challenge is how to analyze and check these models with tools support. One effective approach is to project (transform) the design models into multiple domains, then to use existing specialized tools in those domains to perform the checking and analyzing tasks. The second part of this paper demonstrates one particular projection from TCOZ designs to Timed Automata (TA) models so that TA model checkers can be used to check time related properties.
DYNAMIC BEHAVIORS OF HIGH-G MEMS ACCELEROMETER INCORPORATED WITH NOVEL MICRO-FLEXURES
Authors: CHEN BANGTAO , MIAO JIANMIN , LIM CHUNKIAT , TAY FRANCIS E. H. , ILIESCU CIPRIAN
Published: May 2005

In this work, a new MEMS accelerometer with large detectable range of more than 50 g is designed. Three types of flexure designs were studied: the conventional straight flexure, newly proposed interlapped-L flexure and rectangular flexure. Their dimensions were optimized to achieve the desired requirements of the accelerometer. Capacitive sensing method and electrostatic actuation are selected to be the sensing and actuation methods. Governing equations derived from this model are used to compare with that of a second order spring-mass-damper system. These mathematical models are then used to formulate the various types of sensitivities. Finite Element Analysis software ANSYS is used in the design stage to simulate its dynamic behavior. The accelerometers with interlapped-L flexure and rectangular flexure present very large detectable range of 60 g and 80 g, sensitivity of 23.1 and 17.3 fF/g, with the noise floor of 17.9 and 18.2 μ g/(Hz) 1/2 in atmosphere.