			Home About us Contact

Size Ratio (size + ratio)

Distribution by Scientific Domains

Life Sciences	31%
Polymers and Materials Science	15%
Earth and Environmental Science	10%

Selected Abstracts

Liver Graft-to-Recipient Spleen Size Ratio as a Novel Predictor of Portal Hyperperfusion Syndrome in Living Donor Liver Transplantation

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 12 2006
Y.-F. Cheng
Portal hyperperfusion in a small-size liver graft is one cause of posttransplant graft dysfunction. We retrospectively analyzed the potential risk factors predicting the development of portal hyperperfusion in 43 adult living donor liver transplantation recipients. The following were evaluated: age, body weight, native liver disease, spleen size, graft size, graft-to-recipient weight ratio (GRWR), total portal flow, recipient portal venous flow per 100 g graft weight (RPVF), graft-to-recipient spleen size ratio (GRSSR) and portosystemic shunting. Spleen size was directly proportional to the total portal flow (p = 0.001) and RPVF (p = 0.014). Graft hyperperfusion (RPVF flow >250 mL/min/100 g graft) was seen in eight recipients. If the GRSSR was <0.6, 5 of 11 cases were found to have graft hyperperfusion (p = 0.017). The presence of portosystemic shunting was significant in decreasing excessive RPVF (p = 0.059). A decrease in portal flow in the hyperperfused grafts was achieved by intraoperative splenic artery ligation or splenectomy. Spleen size is a major factor contributing to portal flow after transplant. The GRSSR is associated with posttransplant graft hyperperfusion at a ratio of <0.6. [source]

Inter-sexual combat and resource allocation into body parts in the spider, Stegodyphus lineatus

ECOLOGICAL ENTOMOLOGY, Issue 6 2006
ALEXEI A. MAKLAKOV
Abstract 1.,Sexual conflict, which results from the divergence of genetic interests between males and females, is predicted to affect multiple behavioural, physiological, and morphological traits. 2.,Sexual conflict over mating may interact with population density to produce predictable changes in resource allocation into inter-sexual armament. 3.,In the spider Stegodyphus lineatus, males fight with females over re-mating. The outcome of the fight is influenced by the cephalothorax size of the contestants. The investment in armament , the cephalothorax, may be traded-off against investment in abdomen, which is a trait that affects survival and fecundity. Pay-offs may depend on population density. Both sexes are expected to adjust resource allocation into different body parts accordingly. 4.,Males had increased cephalothorax/body size ratio in low densities where probability of finding another receptive female is low and females had increased cephalothorax/body size ratio in high densities where cumulative costs of multiple mating are high. 5.,The results support the theoretical conjecture that population density affects resource allocation into inter-sexual armament and call for further research on the interaction between sexual selection and population density. [source]

Confinement effects on the morphology of photopatterned porous polymer monoliths for capillary and microchip electrophoresis of proteins

ELECTROPHORESIS, Issue 14 2008
Mei He
Abstract We find that the morphology of porous polymer monoliths photopatterned within capillaries and microchannels is substantially influenced by the dimensions of confinement. Porous polymer monoliths were prepared by UV-initiated free-radical polymerization using either the hydrophilic or hydrophobic monomers 2-hydroxyethyl methacrylate or butyl methacrylate, cross-linker ethylene dimethacrylate and different porogenic solvents to produce bulk pore diameters between 3.2 and 0.4,µm. The extent of deformation from the bulk porous structure under confinement strongly depends on the ratio of characteristic length of the confined space to the monolith pore size. The effects are similar in cylindrical capillaries and D-shaped microfluidic channels. Bulk-like porosity is observed for a confinement dimension to pore size ratio >10, and significant deviation is observed for a ratio <5. At the extreme limit of deformation a smooth polymer layer ,300 nm thick is formed on the surface of the capillary or microchannel. Surface tension or wetting also plays a role, with greater wetting enhancing deformation of the bulk structure. The films created by extreme deformation provide a rapid and effective strategy to create robust wall coatings, with the ability to photograft various surface chemistries onto the coating. This approach is demonstrated through cationic films used for electroosmotic flow control and neutral hydrophilic coatings for electrophoresis of proteins. [source]

Female Preferences for Sailfin and Body Size in the Sailfin Molly, Poecilia latipinna

ETHOLOGY, Issue 5 2004
R. David MacLaren
We tested the mating preference of female sailfin mollies (Poecilia latipinna) by presenting them with pairs of dummy males differing in: (I) sailfin and body size together (holding sailfin : body size ratio constant); (II) body size alone (holding sailfin size constant); (III) sailfin size alone (holding body size constant); and (IV) sailfin : body size ratio (holding total lateral projection area constant). Females spent more time near dummies of greater sailfin or greater body size. The preference functions based on the first three sets of stimuli showed a similar pattern: the preference between any two simultaneously presented dummies increased with the magnitude of the discrepancy in lateral projection area (LPA) between them. However, when LPA was held constant in expt (IV), neither body size, sailfin size, nor any particular dummy (i.e. any particular sailfin + body size combination) was preferred. These findings suggest that increased LPA is more stimulating to sexually receptive females and that females consequently prefer larger males. The sailfin may therefore have evolved as a way for males to exploit this sensory bias and appear larger to prospective mates. [source]

Diffusion of semi-flexible polyelectrolyte through nanochannels

AICHE JOURNAL, Issue 7 2010
Hongyan Gu
Abstract The diffusion of sodium polystyrene sulfonate through polycarbonate nanochanels was studied in salt-free dilute aqueous solution. A stronger molecular weight dependence of diffusion was observed compared to free diffusion in dilute solution. Scaling exponentials relating polymer size to diffusivity were between Flory's theory (Deff , N,0.6) and Rouse's model (Deff , N,1), revealing a crossover regime from 3-D diffusion to 1-D diffusion. Diffusion was less hindered for the polyelectrolyte (Deff/D0), than for a rigid sphere, when the polymer/channel size ratio exceeded 0.2. This is attributed to elongated chains with reduced frictional hindrance. Simulation of the confined diffusion based on an elongated cigar model gave D , N,1 while the experimental results agree with D , N,0.94. For charged polyelectrolytes, the transition to 1-D diffusion therefore begins before the polymer radius of gyration exceeds the channel size contrary to model assumptions. We attribute this to the charged nature of the polyelectrolytes causing extended chain conformations. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

Fluid-particle drag in low-Reynolds-number polydisperse gas,solid suspensions

AICHE JOURNAL, Issue 6 2009
Xiaolong Yin
Abstract Lattice-Boltzmann simulations of low-Reynolds-number fluid flow in bidisperse fixed beds and suspensions with particle,particle relative motions have been performed. The particles are spherical and are intimately mixed. The total volume fraction of the suspension was varied between 0.1 and 0.4, the volume fraction ratio ,1/,2 from 1:1 to 1:6, and the particle size ratio d1/d2 from 1:1.5 to 1:4. A drag law with improved accuracy has been established for bidisperse fixed beds. For suspensions with particle,particle relative motions, the hydrodynamic particle,particle drag representing the momentum transfer between particle species through hydrodynamic interaction is found to be an important contribution to the net fluid-particle drag. It has a logarithmic dependence on the lubrication cutoff distance and can be fit as the harmonic mean of the drag forces in bidisperse fixed beds. The proposed drag laws for bidisperse fixed beds and suspensions are generalized to polydisperse suspensions with three or more particle species. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Agglomeration modeling of small and large particles by a diffusion theory approach

AICHE JOURNAL, Issue 5 2009
Alvaro Realpe
Abstract The interaction particle-binder during the wet granulation process plays a major role in the agglomeration of particles. This interaction has been modeled by a force balance acting on the particle where the binder's viscous force increases the strength of liquid bridge and facilitates the particle agglomeration. In this work, agglomeration kernels based on Brownian movement approach of small particles in the binder layer, the size ratio between particles (monodispersed and polydispersed), and binder's viscous forces were considered to model the wet granulation process of pharmaceutical powders in a laboratory-scale high shear mixer. The assumptions of no-stationary and pseudostationary behavior were suitable to describe the growth kinetics of the two stages (fast and slow) observed. A volume ratio of 150 between large and small particles produces the most effective granulation growth. The developed kernels were tested simulating experimental data obtained from a high shear mixer. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]

Polymer Chain Collapse in Supercritical Fluids.

MACROMOLECULAR SYMPOSIA, Issue 1 2009

Abstract A few years ago we reported the first observation, by computer simulations, of polymer chain collapse near the lower critical solution temperature (LCST).1 In the present work, we extended the above study to understand the underlying physics of a single polymer chain collapse near LCST and its relationship to phase boundaries in the T-x plane. Effects of solvent and monomer sizes, and solvent and monomer energetic interactions are studied. Using Monte Carlo simulations, the mean end-to-end distance (R) and gyration radius (Rg) are calculated for a single chain in a supercritical fluid solvent over a broad range of densities, pressures and temperatures. In general, the chain collapses as temperature increases at constant pressure. Upon a further temperature increase, the chain expands again to approach the athermal limit provided that the temperature is sufficiently high. The collapse is related to an LCST phase boundary while the expansion represents the signature of an upper-critical solution temperature (UCST) suggesting the existence of a closed-immiscibility loop. By manipulating the strength of the energetic interactions as well as the solvent-to-monomer size ratio, the size of the size of the immiscibility loop can be fine-tuned. The relationship among size and the segment-solvent energetic interaction are correlated by a conformational parameter (,) for the first time. By monitoring the , behavior, it is possible to predict solution's phase behavior, transition zone from LCST-UCST in a closed-loop miscibility behavior. The above relationship between chain conformation to phase boundaries may be useful in understanding phase stability in compressible polymer-solvent mixtures. [source]

Experimental optimization of the 2nd loop configuration for feedforward amplifiers in terms of their efficiency and linearity

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2006
Sung-Chan Jung
Abstract In this paper, we report the results of the experimental optimization of the 2nd -loop configuration for feedforward amplifiers in terms of their efficiency and linearity. We consider two parameters in the 2nd -loop of a feedforward amplifier: (i) the size ratio between the main and error amplifiers and (ii) the coupling factor of the error signal coupler. Experiments are performed using a multicarrier down-link WCDMA signal under various configurations. The measured data, which are normalized with respect to the overall power capacity of the main and error amplifiers, show that, among the different 2nd -loop configurations, the best compromised efficiency (13.4%) at a given adjacent channel leakage ratio (ACLR) level (,50 dBc) is observed for a size ratio of around 3.0 and a coupling factor of around 7.2 dB. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 617,621, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21425 [source]

Intracluster light and the extended stellar envelopes of cD galaxies: an analytical description

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
Marc S. Seigar
ABSTRACT We have analysed deep R -band images, down to a limiting surface brightness of 26.5 R-mag arcsec,2 (equivalent to ,28 B-mag arcsec,2), of five cD galaxies to determine the shape of the surface brightness profiles of their extended stellar envelopes. Both de Vaucouleurs R1/4 and Sérsic R1/n models, on their own, provide a poor description of the surface brightness profiles of cD galaxies. This is due to the presence of outer stellar envelopes, thought to have accumulated over the merger history of the central cluster galaxy and also from the tidal stripping of galaxies at larger cluster radii. We therefore simultaneously fit two Sérsic functions to measure the shape of the inner and outer components of the cD galaxies. We show that, for three out of our five galaxies, the surface brightness profiles are best fitted by an inner Sérsic model, with indices n, 1 ,6, and an outer exponential component. For these systems, the galaxy-to-envelope size ratio is 0.1,0.4 and the contribution of the stellar envelope to the total R -band light (i.e. galaxy + envelope) is around 60,80 per cent (based on extrapolation to a 300 kpc radius). The exceptions are NGC 6173, for which our surface brightness profile modelling is consistent with just a single component (i.e. no envelope) and NGC 4874 which appears to have an envelope with a de Vaucouleurs, rather than exponential, profile. [source]

Evaluation of Digital Image Discretization Error in Droplet Shape Measurement Using Simulation

PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 5-6 2009
Sina Ghaemi
Abstract Droplet shape measurement using image based techniques can be conducted using shape parameters which consist of a number of geometric features of a droplet image. The accuracy of calculating these shape parameters and their capability in revealing shape deviation is considerably affected by the discretization of the image with a camera CCD. In this paper, a simulation of digital images is conducted to investigate the error caused by image discretization. The effect of this error on calculating area, perimeter, and also a selected number of shape parameters are investigated. Digital images of circular and elliptical discs at different image/pixel size ratio and locations relative to the pixel grid have been generated to simulate the projected view. Results show that the shape parameters demonstrate different levels of sensitivity to the desirable factor of shape deviation and the undesirable factor of image discretization. A "clearance factor" has been suggested and used to rank the shape parameters based on their compensation between sensitivity to shape deviation and image discretization. [source]

Liver Graft-to-Recipient Spleen Size Ratio as a Novel Predictor of Portal Hyperperfusion Syndrome in Living Donor Liver Transplantation

Persistence of resprouting species after fire in natural and post-mine restored shrublands in southwestern Australia

APPLIED VEGETATION SCIENCE, Issue 4 2009
D.N. Herath
Abstract Questions: Is post-fire persistence of resprouting species lower in restored sites, and is survival related to lignotuber size? Location: Southwestern Australia, Eneabba, 300 km north of Perth. Methods: Post-fire persistence of 10 lignotuberous shrub species was compared between three sites restored 8,24 years ago after mineral-sand mining and three surrounding natural shrubland sites (8,24 years since previous fire). Results: Overall persistence of species was 11,93% in restored sites (mean 52%) and 79,100% in natural sites (mean 96%). Persistence increased with time since rehabilitation for five species with <25% of individuals in three species surviving in the youngest stand. For equivalent crown size, average lignotuber circumferences were 50% smaller at restored sites and this probably accounted for their higher post-fire mortality. Apart from differences in the age of plants, restored sites had lower soil penetrability than natural sites, which may have restricted rootstock development. A tradeoff favoring a higher crown volume to lignotuber size ratio was apparent in nine of the ten species with greater crown volumes (by 37%) and smaller lignotubers (by 36%) in restored sites. Two resprouting species for which crown seed store was quantified had much higher fecundity in restored sites. Conclusions: Fires reduced resprouter persistence in restored sites owing to poor development/insufficient size of lignotubers. Further management after fires is required, including application of resprouter seeds/seedlings on restored topsoil, transplanting adult resprouters (where viable) from natural areas ahead of the mining front. Low intensity/patchy fires are recommended on long unburnt sites. Resprouter survival would have likely been much greater in the first place if a deeper sandy soil profile was rehabilitated, thereby providing a more suitable medium for lignotuber development. [source]

Seed Dispersal and Ingestion of Insect-Infested Seeds by Black Howler Monkeys in Flooded Forests of the Parana River, Argentina

BIOTROPICA, Issue 4 2008
Susana Patricia Bravo
ABSTRACT All howler monkey species (Alouatta spp.) have a folivorous,frugivorous diet. Howler monkeys are reported to be seed dispersers in several areas, including black howlers (Alouatta caraya), which are important seed dispersers in northern Argentinean forests. The goal of this work was to study the three-way interaction between insects, seeds, and black howlers, and assess the functional significance of this tri-trophic interaction for seed dispersal. I determined through direct observation that fruits of species with a high proportion of insect infestation were important components of howler monkey diet. Ocotea diospyrifolia seeds from fresh faeces of black howlers contained dead larvae, but seeds were still able to germinate. Seeds in which larvae had reached an advanced stage of development did not germinate. Larvae of infested Eugenia punicifolia fruits were killed by digestion when they occurred in the pulp early in the fruiting season, but were dispersed alive with seeds later in the season. Banara arguta fruits contained both healthy and infested seeds; infested seeds were destroyed during digestion, while healthy seeds were dispersed. Black howlers' ingestion of infested fruits could result in the: (1) killing of larvae and dispersion of healthy seeds; (2) spread of larvae; or (3) destruction of infested seeds. This will depend on the relationship between the time at which fruit is consumed by black howlers, the time at which insect infestation occurs, and also probably on the hardness of the seed coat and the seed,insect size ratio. RESUMEN Todas las especies de monos aulladores (Alouatta spp.), poseen dietas folívoro-frugívoras. Los monos aulladores han sido reportados en varias ocasiones como dispersores de semillas, incluído Alouatta caraya, el cual es un importante dispersor de semillas en las selvas del norte de Argentina. El objetivo de este trabajo fue estudiar la interacción triple insectos,semillas,Alouatta caraya y determinar su significado funcional para el proceso de dispersión de semillas. Se determinó por observación directa que el consumo de frutas de las especies que poseían una alta infestación por insectos representaba una alta proporción de la dieta. Las semillas de Ocotea diospyrifolia colectadas de heces frescas de A. caraya contenían larvas muertas y su capacidad germinativa intacta. Las semillas en las cuales las larvas habían alcanzado un avanzado estado de desarrollo ya no podían germinar. Al principio de la estación de fructificación las larvas que infestaban las frutas de Eugenia punicifolia se encontraban en la pulpa y morían al ser ingeridas por A. caraya, pero cuando, avanzada la fructificación, las larvas se movían hacia las semillas, eran dispersadas vivas dentro de las mismas. Las frutas de Banara arguta contenían tanto semillas infestadas como sanas; las infestadas fueron destruidas por la digestión mientras que las sanas eran dispersadas. La ingestión de frutas infestadas por parte de A. caraya puede llevar a: (1) la muerte de las larvas y la dispersión de semillas sanas, (2) la dispersión de larvas o (3) la destrucción de las semillas infestadas. Esto depende de la relación entre el tiempo en que es ingerida la fruta por A. caraya y el tiempo en que se produjo la infestación, probablemente también sea importante la dureza de la cubierta de la semilla y la relación entre el tamaño de la semilla y el de la larva. [source]

Cuticle micromorphology of leaves of Pinus (Pinaceae) from Mexico and Central America

BOTANICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2001
SUNG SOO WHANG
Cuticle micromorphology of 34 taxa of Pinus from Mexico and Central America was studied with scanning electron microscopy, and leaf morphology was described. In total, 29 characters, 22 from the inner cuticular surfaces and seven from the outer, were described in detail. These characters have value either for testing infragenerie classifications or for identifying individual taxa. Characters relating to the periclinal wall texture of the epidermal cells, the shape and degree of development of the anticlinal walls of the epidermal cells, the basal and apical shapes of anticlinal epidermal cell walls, the continuity of the epidermal cells, the size ratio of the polar to lateral subsidiary cells, the grooves on subsidiary cells, the cuticular flanges between guard and subsidiary cells, the groove near the bristles and the elevation of the Florin ring ridge and striations on the Florin ring are particularly useful for infrageneric classification. The agreement between these characters and infrageneric classifications is discussed. Characters relating to the end wall shapes of the epidermal cells, the relative length of epidermal cells, the shape of the stomatal apparatus, the texture of guard and lateral subsidiary cell surfaces, the polar extensions, the number of subsidiary cells and epidermal cell layers between stomatal rows, the integrity of stomatal rows, cell numbers between stomata in a row, cuticular flanges between guard cells, bristle flanges and surface textures, epicuticular waxes, striations on Florin rings and stomatal shapes, contain some important information for identifying Mexican pines. The distribution of the states of each character is compared with that of the Asian pines. Cuticular characters are used to help determine the affinities of taxonomically difficult taxa. [source]

Self-Assembled Surface Patterns of Binary Colloidal Crystals

ADVANCED MATERIALS, Issue 1 2003
V. Kitaev
Co-assembly of binary dispersions of monodisperse microspheres with large size ratios has been used to produce well-ordered hexagonally close-packed monolayers of large spheres with a superimposed pattern of small spheres (see Figure). The architectures obtained are determined by the size and concentration ratios of the microspheres in the dispersions, are very diverse, and can be obtained reproducibly over millimeter length scales. [source]

Development of psychophysics in Japan,

JAPANESE PSYCHOLOGICAL RESEARCH, Issue 4 2008
TADASU OYAMA
Abstract:, In Japan, psychophysics began as early as 1888 with the first lecture on it given by Yujiro Motora at the Imperial University (the University of Tokyo), following the completion of his PhD, at the laboratory of G. S. Hall. In 1910, A Photographic Album of Experimental Psychology was published, which included many photographs of psychophysical experiments. In 1933, Sadaji Takagi conducted the first experiment on animal psychophysics to investigate shape constancy in small birds. In 1949, the first experiment on infant psychophysics was conducted by Jyuji Misumi to study the early development of size constancy. And, in 1955, Tadasu Oyama proposed a new psychophysical technique, naming the method of transposition to measure perceived size ratios without using numerical expressions. This method has been successfully applied to the measurement of illusions, figural after-effects, and size constancy. In 1960, Tarow Indow and his collaborators published their first systematic application of multidimensional scaling to color perception. They also applied it to study the perceptual structure of visual space. Recent developments in those topics in Japan are also reviewed. [source]

Male reproductive competition in spawning aggregations of cod (Gadus morhua, L.)

MOLECULAR ECOLOGY, Issue 1 2002
D Bekkevold
Abstract Reproductive competition may lead to a large skew in reproductive success among individuals. Very few studies have analysed the paternity contribution of individual males in spawning aggregations of fish species with huge census population sizes. We quantified the variance in male reproductive success in spawning aggregations of cod under experimental conditions over an entire spawning season. Male reproductive success was estimated by microsatellite-based parentage analysis of offspring produced in six separate groups of spawning cod. In total, 1340 offspring and 102 spawnings distributed across a spawning season were analysed. Our results show that multiple males contributed sperm to most spawnings but that paternity frequencies were highly skewed among males, with larger males on average siring higher proportions of offspring. It was further indicated that male reproductive success was dependent on the magnitude of the size difference between a female and a male. We discuss our results in relation to the cod mating system. Finally, we suggest that the highly skewed distribution of paternity success observed in cod may be a factor contributing to the low effective population size/census population size ratios observed in many marine organisms. [source]

Dynamics of intracohort cannibalism in cultured fish

AQUACULTURE RESEARCH, Issue 7 2002
E Baras
Abstract Cannibalism is a frequent phenomenon in fish, especially in culture environments where fish are unable to escape predation via habitat segregation or migration. Not all cultured fish species start to exhibit cannibalism at the same age or size, nor is cannibalism equally intense in different species or life stages. Predator to prey size ratios vary substantially between species and life stages, chiefly because cannibalism is governed by gape size limitations and allometric growth of mouthparts. The development of sense organs, hard body parts, swimming and escape capacities in both the predator and the prey also influence prey size selectivity. The dynamics of cannibalism are influenced by these, as well as by environmental, factors that have effects on feed intake, growth depensation and facilitate or complicate the displaying of cannibalistic behaviour. Knowledge about cannibalistic behaviour and the logistics of cannibalism along with environmental enhancement are prerequisites for the mitigation of cannibalism in aquaculture. Also, within the context of strain selection, it is of importance to determine whether cannibals are natural-born killers or just lottery winners. These factors are discussed, chiefly as they apply to intracohort cannibalism. In addition, guidelines are suggested for cannibalistic risk assessment, and methods for mitigation of cannibalism are discussed. [source]