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Smaller Ones (smaller + ones)
Selected AbstractsEMPLOYMENT TAXES: WHERE ARE WE GOING?ECONOMIC AFFAIRS, Issue 1 2003John Whiting Employment taxes have become more complicated over time, and too much of an administrative burden is now placed on employers, especially smaller ones. Combining PAYE and NIC has the potential for big simplification of the system. My basic thesis is that circumstances have changed dramatically, and so must the system, because all is not well in the employment taxes area. [source] PERSPECTIVE: THE SIZE-COMPLEXITY RULEEVOLUTION, Issue 9 2004J. T. Bonner Abstract It is widely accepted that bigger entities have a greater division of labor than smaller ones and this is reflected in the fact that larger multicellular organisms have a corresponding increase in the number of their cell types. This rule is examined in some detail from very small organisms to large animals, and plants, and societies. Compared to other size-related rules, the size-complexity rule is relatively rough and approximate, yet clearly it holds throughout the whole range of living organisms, as well as for societies. The relationship between size and complexity is analyzed by examining the effects of size increase and decrease: size increase requires an increase in complexity, whereas size decrease permits, and sometimes requires, a decrease in complexity. Conversely, an increase or decrease in complexity permits, but does not require changes in size. An especially compelling argument for the close relation between size and complexity can be found in size quorum sensing in very small multicellular organisms. [source] The effect of stocking size on the first winter survival of whitefish, Coregonus lavaretus (L.), in the Gulf of Bothnia, Baltic SeaFISHERIES MANAGEMENT & ECOLOGY, Issue 2 2002E. JOKIKOKKO The anadromous whitefish, Coregonus lavaretus (L.), is the most numerous fish species stocked in the Gulf of Bothnia, Baltic Sea. One-summer-old-whitefish fingerlings are mostly 8,10 cm long when released annually in September,October, whereas the wild whitefish are 10,12 cm at that time. About 6 million, one-summer-old, spray-marked, whitefish were released in the northern and central parts of the Gulf in 1995,1998. To study the effect of the stocking length on the survival of the marked fish, the length of the recaptured whitefish as 1-year-olds was back-calculated. Altogether 1106 whitefish recaptured in the Gulf of Bothnia were analysed. The back-calculated length was slightly greater than the stocking length but not as large as the length of the wild fish. In the central part of the Gulf of Bothnia, where the mean stocking length was more than 10 cm, the back-calculated length was 10.5,11.1 cm. In the northern part of the Gulf the mean stocking length varied between 8.8 and 10.0 cm annually, and the corresponding back-calculated mean lengths were 9.3,9.7 cm. It also seemed that bigger fingerlings started their feeding migration earlier or they migrated faster than the smaller ones to the southern parts of the Gulf of Bothnia. [source] THE FLUCTUATIONS OF ITALIAN GLACIERS DURING THE LAST CENTURY: A CONTRIBUTION TO KNOWLEDGE ABOUT ALPINE GLACIER CHANGESGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 3 2007MICHELE CITTERIO ABSTRACT. This paper describes the recent evolution of Italian glaciers through an analysis of all available terminus fluctuation data that the authors have entered in a glaciers database (named GLAD) containing 883 records collected on glaciers from 1908 to 2002. Furthermore, a representative subset of data (249 glaciers located in Lombardy) was analysed regarding surface area changes. For the analysis of terminus fluctuations, the glaciers were sorted by size classes according to length. The data showed that during the 20th century Italian Alpine glaciers underwent a generalized retreat, with one distinct and well documented readvance episode that occurred between the 1970s and mid-1980s, and a poorly documented one around the early 1920s. The rates of terminus advance and retreat have changed without significant delays for the larger glaciers with respect to the smaller ones. However, the smaller the glacier, the more limited the advance (if any) during the 1970s and early 1980s. The behaviour of glaciers shorter than 1 km appears to have changed in the last decade, and between 1993 and 2002 they retreated at a very high rate. The analysis of the subset of data led to a quanti-fication of surface reduction of c. 10% from 1992 to 1999 for glaciers in Lombardy. Small glaciers proved to contribute strongly to total area loss: in 1999, 232 glaciers (c. 90% of the total) were smaller than 1 km2, covering 27.2 km2 (less than 30% of the total area), but accounted for 58% of the total loss in area (they had lost 7.4 km2). [source] A Relational Approach to Measuring Competition Among HospitalsHEALTH SERVICES RESEARCH, Issue 2 2002Min-Woong Sohn Objective. To present a new, relational approach to measuring competition in hospital markets and to compare this relational approach with alternative methods of measuring competition. Data Sources. The California Office of Statewide Health Planning and Development patient discharge abstracts and financial disclosure files for 1991. Study Design. Patient discharge abstracts for an entire year were used to derive patient flows, which were combined to calculate the extent of overlap in patient pools for each pair of hospitals. This produces a cross-sectional measure of market competition among hospitals. Principal Findings. The relational approach produces measures of competition between each and every pair of hospitals in the study sample, allowing us to examine a much more "local" as well as dyadic effect of competition. Preliminary analyses show the following: (1) Hospital markets are smaller than thought. (2) For-profit hospitals received considerably more competition from their neighbors than either nonprofit or government hospitals. (3) The size of a hospital does not matter in the amount of competition received, but the larger hospitals generated significantly more competition than smaller ones. Comparisons of this method to the other methods show considerable differences in identifying competitors, indicating that these methods are not as comparable as previously thought. Conclusion. The relational approach measures competition in a more detailed way and allows researchers to conduct more fine-grained analyses of market competition. This approach allows one to model market structure in a manner that goes far beyond the traditional categories of monopoly, oligopoly, and perfect competition. It also opens up an entirely new range of analytic possibilities in examining the effect of competition on hospital performance, price of medical care, changes in the market, technology acquisition, and many other phenomena in the health care field. [source] Body condition, growth rates and diet of Skylark Alauda arvensis nestlings on lowland farmlandIBIS, Issue 3 2001PAUL F. DONALD Factors affecting the diet, body condition and growth rates of Skylark chicks were assessed to examine their relationship to their agricultural environment during a critical period in the life cycle of this rapidly declining species. Rainfall explained the greatest amount of variation in body condition and growth rates and had a negative effect on both. Body condition indices were a good predictor of the likelihood of future partial brood loss to starvation. Low body condition in grass fields was related to a low diversity in the diet. Chicks fed insect larvae had higher body condition indices than those not fed larvae. Larger broods tended to have higher growth rates than smaller ones, whereas smaller broods tended to have higher body condition indices. Natural brood size reduction through the non-hatching of eggs resulted in higher body condition indices than were found in nests with the same number of chicks where all eggs hatched, this effect being independent of absolute brood size. There was no significant difference between crop types in the distance adult birds flew to forage for food for nestlings and foraging crop destination had no effect on chick development. Differences between crop types in chick diet could be related to the documented effects of pesticides on different prey species. We suggest that recent agricultural changes have affected diet and possibly body condition, but that these effects are unlikely to have been an important factor in recent population declines. [source] Cyclic fatigue resistance and three-dimensional analysis of instruments from two nickel,titanium rotary systemsINTERNATIONAL ENDODONTIC JOURNAL, Issue 10 2006N. M. Grande Abstract Aim, To determine how instrument design affects the fatigue life of two nickel,titanium (Ni,Ti) rotary systems (Mtwo and ProTaper) under cyclic fatigue stress in simulated root canals. Methodology, Cyclic fatigue testing of instruments was performed in stainless steel artificial canals with radii of curvature of 2 or 5 mm and an angle of curvature of 60°. A total of 260 instruments were rotated until fracture occurred and the number of cycles to failure were recorded. The morphology of Ni,Ti rotary instruments was investigated by measuring the volume of millimetre slices of each instrument size starting from the tip to the shank by means of ,CT analysis. The fracture surface of three representative samples of each size was analysed by scanning electron microscopy (SEM). Data were analysed by one-way anova, Holm t -test, paired t -test and linear regression; the significance was determined at the 95% confidence level. Results, Cycles to failure significantly decreased as the instrument volume increased for both the radii of curvature tested (P < 0.01). The radius of curvature had a statistically significant influence on the fatigue life of the instruments (P < 0.05). Larger instruments underwent fracture in less time under cyclic stress than smaller ones. SEM evaluation showed typical features of fracture through fatigue failure. Conclusions, The metal volume in the point of maximum stress during a cyclic fatigue test could affect the fatigue life of Ni,Ti rotary instruments. The larger the metal volume, the lower the fatigue resistance. [source] Comparison of the numerical stability of methods for anharmonic calculations of vibrational molecular energiesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 10 2007Petr Dan Abstract On model examples, we compare the performance of the vibrational self-consistent field, variational, and four perturbational schemes used for computations of vibrational energies of semi-rigid molecules, with emphasis on the numerical stability. Although the accuracy of the energies is primarily dependent on the quality of the potential energy surface, approximate approaches to the anharmonic vibrational problem often do not converge to the same results due to the approximations involved. For furan, the sensitivity to variations of the anharmonic potential was systematically investigated by adding random noise to the cubic and quartic constants. The self-consistent field methods proved to be the most resistant to the potential variations. The second order perturbational techniques are sensitive to random degeneracies and provided the least stable results. However, their stability could be significantly improved by a simple generalization of the perturbational formula. The variational configuration interaction is practically limited by the size of the matrix that can be diagonalized for larger molecules; however, relatively fewer states need to be involved than for smaller ones, in favor of the computing. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source] The stratification theory for plant coexistence promoted by one-sided competitionJOURNAL OF ECOLOGY, Issue 3 2009Takashi Kohyama Summary 1It is an essential feature of plants that leaves at higher levels have better access to light than those at lower levels. Thus, larger plants generally enjoy greater success in competing for light than smaller ones. We analyse the effect of such size-asymmetry, or one-sided competition, on the successful coexistence of plant species, using an analytically tractable model for stratified populations, in which a plant in the same layer exhibits the same crowding effect as any other, irrespective of species. 2A two-layer population that is reproductive in upper layer and juvenile in lower layer has a uniquely stable (plant-size-weighted) equilibrium density, as long as its fecundity is sufficient to compensate for its mortality rate. We also calculate a unique threshold lower-layer density of this layered population when there is no upper-layer plant. This threshold lower-layer density is larger than the weighted equilibrium density with upper layer, except for the case of perfect two-sided competition. 3A two-layer species can stably coexist with a one-layer, understorey species as a result of one-sided, but not two-sided competition. The coexistence condition is that the equilibrium density of the one-layer species lies between the threshold lower-layer density and the equilibrium density of the two-layer species. For an understorey species to coexist successfully with a two-layer species, any advantage in demographic performance, most prominently in a sufficiently high fecundity per plant must offset the disadvantage of living in dark conditions. 4Results from a model of multi-layer populations suggest that several species differing in terms of maximum layer and fecundity can coexist under conditions of one-sided competition. We demonstrate an example of the stable coexistence of eight species. The inter-specific trade-offs predicted by the model correspond to patterns observed in a rain forest. 5Synthesis. We propose a stratification theory that explains the generation and maintenance of the successful coexistence of plant species. Under the condition of one-sided competition, a canopy population that takes advantage of escaping from understorey competition shows an ability to invade an understorey with a density higher than its own equilibrium density, and which offers opportunities for an understorey population with high fecundity and/or shade tolerance to coexist. The predicted coexistence of species that share maximum canopy height is most pronounced for trees of tropical rain forests. [source] Dentition in the African catfishes Andersonia (Amphiliidae) and Siluranodon (Schilbeidae) previously considered toothlessJOURNAL OF FISH BIOLOGY, Issue 1 2004A. S. Golubtsov Based on light and scanning electron microscopic examination of their morphology, the dentition on both the premaxilla and dentary of Andersonia(Amphiliidae) and Siluranodon(Schilbeidae) catfishes is described from samples taken from tributaries of the White Nile in south-western Ethiopia. These monotypic African genera were previously believed to lack teeth on the lower jaw in Andersonia and on both jaws in Siluranodon. Siluranodon exhibits an ontogenetic reduction: teeth were less frequently found in larger individuals than in smaller ones. In contrast to the adults of all other schilbeids, whose oral teeth are arranged in multiserial (or at least, biserial) bands, Siluranodon has uniserial teeth on both the premaxilla and the dentary. The adaptive, ontogenetic and phylogenetic aspects of jaw-tooth reduction in catfishes are discussed. [source] Effects of Size of Cellulose Granules on Dough Rheology, Microscopy, and Breadmaking PropertiesJOURNAL OF FOOD SCIENCE, Issue 2 2007M. Seguchi ABSTRACT:, Breadmaking was performed with cellulose-blended wheat flour. Cellulose granules (7 types) of various sizes (diameter) were prepared by kneading. With increase of the blend percent of the cellulose samples from 10% to 20%, breadmaking properties such as bread height and specific volume (SV) gradually decreased in every sample; however, the decreasing levels of the properties in 7 types of various sizes varied. The decrease of bread height and SV was associated with the size of the cellulose granule. It was observed at both 10% and 20% blends that the same bread height and SV as for bread baked with only wheat flour could be obtained when the diameter of cellulose granule was above 154 ,m in cellulose/wheat flour breadmaking, while they gradually decreased with granules below 154 ,m. When the largest cellulose granules were mechanically ground to make smaller ones, the bread height and SV decreased with increasing grinding time. It was ascertained that the size of the cellulose granule was important for breadmaking properties. Cellulose-blended wheat flour was subjected to mixograph tests. When cellulose granules above 154-,m dia were blended with wheat flour, the profile of the mixogram was almost the same as that for wheat flour; that is, the profile had a short mixing requirement and showed a viscous gluten matrix. However, when cellulose granules below 81-,m dia were blended, a different curve showing a nonviscous dough due to breakdown of the gluten protein was observed, as ascertained by microscopy. Farmograph test showed that the amount of the released gas from cellulose-blended bread dough increased with decrease of the size of the cellulose granule due to breakdown of the gluten protein. [source] Longitudinal and Radial Gradients of PO2 in the Hamster Cheek Pouch MicrocirculationMICROCIRCULATION, Issue 3 2008Helena Carvalho ABSTRACT Objectives: The aim of this study was to determine longitudinal and radial gradients in oxygen tension (PO2) in microvessels of the hamster cheek pouch. Methods: We measured PO2 using the phosphorescence-quenching method in two orders of arterioles (45.8 ± 5.5 and 19.9 ± 1.8 , m diameter), capillaries, and two orders of venules (50.5 ± 3.4 and 21.4 ± 2.0 , m diameter) in order to determine the longitudinal PO2 gradient. At the arteriolar and venular sites, we also measured PO2 at four different sites for an analysis of radial PO2 gradients: centerline, inside wall (larger arteriole and venule only), outside wall, and interstitium. We used 10 hamsters weighing 115 ± 27 g anesthetized with pentobarbital intraperitoneally and maintained with alpha-chloralose intravenously. The cheek pouch was everted and a single-layered preparation was studied by intravital microscopy. Albumin-bound Pd-porphyrin was infused into the circulation and excited by flash illumination at 10 Hz, with a rectangular diaphragm limiting the excitation field to 5 × 25 , m. Results: In the longitudinal direction, intravascular PO2 decreased significantly (P < 0.01) from large arterioles (39.5 ± 2.3 mmHg) to small arterioles (32.2 ± 0.3 mmHg), then to capillaries (30.2 ± 1.8 mmHg), and on to small venules (27.3 ± 2.1 mmHg) and large venules (25.5 ± 2.2 mmHg). In the radial direction, PO2 decreased significantly (P < 0.01) in and around larger arterioles, and to a lesser extent, around the smaller ones (P < 0.05). There was no significant PO2 gradient, longitudinal or radial, associated with venules. The PO2 difference from the centerline to the outside wall in large arterioles was 8.3 ± 1.4 mmHg, and most of the decline in PO2 in the radial direction was contributed by the intravascular difference (4.7 ± 2.1 mmHg) and only about 1.0 ± 2.7 mmHg by the transmural difference. Conclusions: Our data show that there are large intra-arteriolar radial PO2 gradients, but no large transmural PO2 differences, suggesting that the oxygen consumption of the microvessel wall is not exceptionally high. [source] A model of cloud fragmentationMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008George B. Field ABSTRACT We present a model in which the supersonic motions observed in molecular clouds are driven by gravitational energy released as large structures fragment into smaller ones. The fragmentation process begins in large molecular clouds, and continues down to fragments of a critical mass defined as the mass at which gravitational confinement may be replaced by pressure confinement. The power laws that describe the scaling of density, mass, and number spectra of the fragments are given in terms of the observed velocity dispersion of the fragments. The results agree with observations over the range from several to about a third of a million solar masses. [source] Female mating success and risk of pre-reproductive death in a protandrous grasshopperOIKOS, Issue 2 2002Raúl Cueva Del Castillo Numerous studies have assessed the adaptive value of protandry for males in several insect species, considering that male emergence is determined by female availability. However, the possible advantage of the time of emergence for females on their mating success in protandrous insect species has only been explored theoretically. By studying the grasshopper Sphenarium purpurascens we evaluated the hypothesis that late emergence could be adaptive for females. If female maturation occurs when the population density is higher and the sex ratio (males/females) is biased to males, their probability of mating increases. Thus, in this study we estimated (1) the opportunity for mating in females as a function of their sexual maturation time, population density, and sex ratio at the moment they reached sexual maturity. In addition, (2) an analysis incorporating female body size and the total number of female matings was performed. Both analyses support the occurrence of protandry in the studied population. Under the first approach, females with intermediate maturation time had a higher probability of being mated than earlier and late matured females. Thus, it suggests that stabilising selection is acting on female maturation time and this may affect selection on male maturation time. Furthermore, the proportion of mated females increased when the sex ratio was biased to males, and stabilising selection on maturation time was detected also. However, the number of matings of a female depended on her body size. Females with larger body size had more matings than smaller ones at the beginning of the reproductive season. Because selection acts differently on maturation time in males and females of S. purpurascens this result is consistent with a condition for the maintenance of protandry in the population. The present results are discussed in the light of the models for the evolution of protandry. [source] Thermal, electrical, and mechanical properties of Si3N4 filled LLDPE compositePOLYMER COMPOSITES, Issue 7 2009Qunli An Silicon nitride (Si3N4) filled linear low-density polyethylene (LLDPE) composite was prepared. The effects of Si3N4 filler content, dispersion, and LLDPE particle size on the thermal conductivity, and Si3N4 filled content on the mechanical and electrical properties of Si3N4 reinforced LLDPE composites prepared using powder mixing were investigated. The results indicate that there existed a unique dispersion state of Si3N4 particles in LLDPE, shell-kernel structure, in which Si3N4 particles surrounded LLDPE matrix particles. With increasing filler content and LLDPE particles size, thermal conductivity increased, and reached 1.42 W/m K at 30 vol% of filler, seven times as that of unfilled LLDPE. Furthermore, the examinations of Agari model demonstrate that larger size LLDPE particles form thermal conductive networks easily compared with smaller ones. The values predicted by theoretical model underestimate the thermal conductivity of Si3N4/LLDPE composites. In addition, the composites still possessed rather higher electrical resistivity and dielectric properties, but the mechanical properties decreased. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source] MANUFACTURING WAGES IN THE ENLARGED EU: THE ROLE OF NEIGHBOUR-COUNTRY EFFECTS*THE MANCHESTER SCHOOL, Issue 1 2009HELENA MARQUES In this paper a New Economic Geography type wage equation is estimated for the EU-25. The determinants of manufacturing wages are shown to be sector-specific and the role of geography is limited. As a consequence, we show that the improvement of the EU's internal market and the evolution of European geography are likely to favour larger EU members and challenge smaller ones. [source] Redetermination of the lanthanum iron sulfide La52Fe12S90ACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2006Allison M. Mills A redetermination of the structure of `La32.66Fe11S60' in the trigonal space group Rm led to the new formula La52Fe12S90 and to a redefinition of the structure type. In the structure, the Fe2+ cations occur in Fe2S9 dimers of face-sharing octahedra (with 3m symmetry). The dimers are linked by face- and vertex-sharing bi- and tricapped LaS6 trigonal prisms (with m symmetry) to form a three-dimensional network containing two types of cuboctahedral cavities. The larger cavities remain empty, while the smaller ones accommodate alternative sites for disordered La3+ cations. [source] Effects of turbidity on feeding of the young-of-the-year pikeperch (Sander lucioperca) in fishpondsAQUACULTURE RESEARCH, Issue 2 2010Priit Zingel Abstract The effect of water turbidity on the prey selection and consumption of the young-of-the-year (YOY) pikeperch in the planktivorous feeding stage was studied. Attention was paid particularly to the question of how the food selectivity depends on the size of YOY pikeperch and how the turbidity affects feeding in different size classes. Studies were carried out in ponds of two fish farms in Estonia over 4 years. Small cladocerans were the most preferred prey in the smallest pikeperch size class. In larger size classes, the most selected prey were the large cladocerans. Water turbidity affected the prey selection of the planktivorous pikeperch significantly. In more turbid environments, the larger zooplankters were more positively selected than the smaller ones. Turbidity decreased both total zooplankton consumption and Fulton's condition factor of fish only in the largest size class of pikeperch. The effect of turbidity on foraging and growth, and thus on the size of juvenile pikeperch of a particular year class is substantial under conditions where juveniles cannot shift from planktivory to piscivory. [source] Photometric and spectroscopic observations of three rapidly rotating late-type stars: EY Dra, V374 Peg, and GSC 02038-00293,ASTRONOMISCHE NACHRICHTEN, Issue 8 2010H. Korhonen Abstract Here, BV (RI)C broad band photometry and intermediate resolution spectroscopy in H, region are presented for two rapidly rotating late-type stars: EY Dra and V374 Peg. For a third rapid rotator, GSC 02038-00293, intermediate resolution H, spectroscopy and low resolution spectroscopy are used for spectral classification and stellar parameter investigation of this poorly known object. The low resolution spectrum of GSC 02038-00293 clearly indicates that it is a K-type star. Its intermediate resolution spectrum can be best fitted with a model with Teff = 4750 K and v sin i = 90 km s,1, indicating a very rapidly rotating mid-K star. The H, line strength is variable, indicating changing chromospheric emission on GSC 02038-00293. In the case of EY Dra and V374 Peg, the stellar activity in the photosphere is investigated from the photometric observations, and in the chromosphere from the H, line. The enhanced chromospheric emission in EY Dra correlates well with the location of the photospheric active regions, indicating that these features are spatially collocated. Hints of this behaviour are also seen in V374 Peg, but it cannot be confirmed from the current data. The photospheric activity patterns in EY Dra are stable during one observing run lasting several nights, whereas in V374 Peg large night-tonight variations are seen. Two large flares, one in the H, observations and one from the broadband photometry, and twelve smaller ones were detected in V374 Peg during the observations spanning nine nights. The energy of the photometrically detected largest flare is estimated to be 4.25 × 1031, 4.3 × 1032 erg, depending on the waveband. Comparing the activity patterns in these two stars, which are just below and above the mass limit of full convection, is crucial for understanding dynamo operation in stars with different internal structures (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The benefit of the retrofitting of a conventional LC system to micro LC: a practical evaluation in the field of bioanalysis with fluorimetric detectionBIOMEDICAL CHROMATOGRAPHY, Issue 5 2003S. Roy Abstract The interests in liquid micro-chromatography (higher column efficiencies, increase in sensitivity) are now well established. The enhancement of fluorimetric response induced by the reduction of the inner diameter of columns (4.6, 3.0, 1.0 and 0.3,mm respectively) coupled with adapted detection cells to control the loss of efficiency (8,µL for the two first columns and 100,nL for the two smaller ones) has been studied in the bioanalytical field, using the plasma determination of native fluorescent antibacterial agents: fluoroquinolones. Ten-fold enhancement of the signal can easily be obtained when substituting a 0.3,mm i.d. column and 100,nL detection cell for a 4.6,mm i.d. column, and 8,µL detection cell. In addition to inner diameter reduction, the detection cell geometry appears to be an essential parameter to obtain the best enhancement of the recorded signal. Hence, the enhancement of signal with micro-chromatography with fluorimetric detection appears to be a compromise between column inner diameter and flow cell volume reduction. Copyright © 2003 John Wiley & Sons, Ltd. [source] Transport characteristics of L -citrulline in renal apical membrane of proximal tubular cellsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 3 2009Keisuke Mitsuoka Abstract L -Citrulline has diagnostic potential for renal function, because its plasma concentration increases with the progression of renal failure. Although L -citrulline extracted by glomerular filtration in kidney is mostly reabsorbed, the mechanism involved is not clearly understood. The present study was designed to characterize L -citrulline transport across the apical membranes of renal epithelial tubular cells, using primary-cultured rat renal proximal tubular cells, as well as the human kidney proximal tubular cell line HK-2. L -Citrulline was transported in a Na+ -dependent manner from the apical side of both cell types cultured on permeable supports with a microporous membrane. Kinetic analysis indicated that the transport involves two distinct Na+ -dependent saturable systems and one Na+ -independent saturable system in HK-2 cells. The uptake was competitively inhibited by neutral and cationic, but not anionic amino acids. Relatively large cationic and anionic compounds inhibited the uptake, but smaller ones did not. In HK-2 cells, mRNA expression of SLC6A19 and SLC7A9, which encode B0AT1 and b0,+AT, respectively, was detected by RT-PCR. In addition, L -citrulline transport was significantly decreased in HK-2 cells in which either SLC6A19 or SLC7A9 was silenced. Hence, these results suggest that amino acid transporters B0AT1 and b0,+AT are involved in the reabsorption of L -citrulline in the kidney, at least in part, by mediating the apical membrane transport of L -citrulline in renal tubule cells. Copyright © 2009 John Wiley & Sons, Ltd. [source] Dung Beetle Assemblages and Seasonality in Primary Forest and Forest Fragments on Agricultural Landscapes in Budongo, UgandaBIOTROPICA, Issue 4 2009Philip Nyeko ABSTRACT Very little is known about the diversity of arthropods in the fast-disappearing fragments of natural forests in sub-Saharan Africa. This study investigated: (1) the influence of forest fragment characteristics on dung beetle species richness, composition, abundance, and diversity; and (2) the relationship between dung beetle assemblages and rainfall pattern. Beetles were sampled through 12 mo using dung baited pitfall traps. A total of 18,073 dung beetles belonging to three subfamilies and 45 species were captured. The subfamily Scarabaeinae was the most abundant (99%) and species rich (89%). Fast-burying tunnellers (paracoprids) were the most dominant functional group. Catharsius sesostris, Copris nepos, and Heliocopris punctiventris were the three most abundant species, and had the highest contributions to dissimilarities between forests. With few exceptions, dung beetle abundance, species richness, and diversity were generally higher in larger forest fragments (100,150 ha) than in smaller ones (10,50 ha) and the nature reserve (1042 ha). Forest fragment size had a highly significant positive relationship with beetle abundance, but only when the nature reserve is excluded in the analysis. Dung beetle abundance and species richness showed direct weak relationships with litter depth (positive) and groundcover (negative) but not tree density, tree species richness, and fragment isolation distance. Dung beetle abundance and species richness were strongly correlated with monthly changes in rainfall. Results of this study indicate that forest fragments on agricultural lands in the Budongo landscape, especially medium-sized (100,150 ha) ones, represent important conservation areas for dung beetles. [source] Importance of Body Size in Determining Dominance Hierarchies among Diverse Tropical Frugivores1BIOTROPICA, Issue 1 2005Aaron R. French ABSTRACT Most studies examining dominance hierarchies have focused at the intraspecific level. While some examples of interspecific hierarchies have been noted, these have usually been limited to a few species in the same taxonomic group that utilize resources in similar ways. Here, we examine evidence for dominance interference competition among vertebrates comprising a diverse frugivore community, including 19 species of birds, squirrels, and primates in a mature Central African rainforest. A total of 38 fruiting trees from 18 species were observed for 2058 h to record dominance interactions between foraging vertebrates. We show that interference competition occurs within and between taxonomically diverse species of vertebrates at fruiting trees. The resulting cross-taxonomic dominance hierarchy includes larger vertebrates, such as primates and hornbills, as well as smaller ones, such as squirrels and parrots. Within this hierarchy, the dominance rank of each species is highly correlated with body mass, and is shown to significantly affect the number of fruits removed from a given tree. Because a majority of tropical tree species depend on vertebrates to disperse their seeds, and particular vertebrates may preferentially disperse the seeds of specific tree species, results may have important conservation implications for the maintenance of tree diversity in regions where populations of larger frugivores have been depressed or extirpated. [source] Aggregation Experiments on Fine Fly Ash Particles in a Gradient Magnetic FieldCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2007W. Li Abstract Aggregation experiments were conducted on two kinds of fly ash particles in the size range of 0.023,9.314,,m in a gradient magnetic field produced by permanent magnetic rings. The two types of fly ash particles were obtained from Dongsheng and Datong coal combustion. The effect of particle size, total particle mass concentration, particle residence time in the magnetic field and gas velocity were examined. Experimental results showed that the removal efficiencies in a gradient magnetic field are much higher than those in a uniform magnetic field. The total and single-sized particle removal efficiencies can be improved by increasing the total particle mass concentrations and the particle residence time in the magnetic field or reducing the gas velocity. Mid-sized particle removal efficiencies are higher than those of the larger and smaller ones. With the increase in total particle removal efficiencies, the particle size corresponding to the maximum values of single-sized particle removal efficiencies and the particle number median diameters both decrease. Both the single-sized and total removal efficiencies for the particles from the Dongsheng coal combustion are higher than those from the Datong coal combustion. [source] The treatment of uveal melanoma with iodine plaque brachytherapyACTA OPHTHALMOLOGICA, Issue 2009T KIVELÄ Purpose To provide an overview of managing uveal melanoma (UM) with iodine brachytherapy (IBT). Methods Personal experience of the author in using IBT since 1990. Results IBT is an effective option for managing a UM of any size, although it is mostly used for medium-sized tumours, preference being given to ruthenium brachytherapy (RBT) when the tumour is <5-6 mm thick and to transscleral local resection when thickness is >6 mm, especially when vision is good. IBT is also a safe alternative to enucleation of large UM >10 mm in thickness if the patient is keen to preserve the eye and motivated to accept eventual complications. The plaque is positioned over the UM with a 1-2 mm safety margin when using a collimated/rimmed plaque. Because of stray radiation, a safety margin is not mandatory when the plaque is non-collimated/non-rimmed. Otherwise, surgical technique does not differ from RBT. An advantage of IBT is that the radioactive seeds are separate from the plaque, allowing economical use of plaques of many different sizes and shapes and individual positioning of the seeds in a conformal way. A disadvantage is a short half-life; the seeds need to be changed every 6 months. The dose the author uses is 80 Gy to tumour apex, which is reduced on an individual basis to 60-70 Gy when the UM is very thick. Local tumour control rate is 90% and, paradoxically, not worse for large UM as compared to smaller ones. There are no unequivocal safety distances for avoiding radiation cataract, maculopathy and optic neuropathy, which are more or less frequent depending on the size and location of the UM. Conclusion IBT achieves good local tumour control of UM of all sizes, but preservation of vision is decidedly less frequent than after RBT, which is always given preference. [source] | ||||||||||||||||||||||||||||