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Average Density (average + density)
Selected AbstractsObservational biases in Lagrangian reconstructions of cosmic velocity fieldsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2008G. Lavaux ABSTRACT Lagrangian reconstruction of large-scale peculiar velocity fields can be strongly affected by observational biases. We develop a thorough analysis of these systematic effects by relying on specially selected mock catalogues. For the purpose of this paper, we use the Monge,Ampère,Kantorovitch (MAK) reconstruction method, although any other Lagrangian reconstruction method should be sensitive to the same problems. We extensively study the uncertainty in the mass-to-light assignment due to incompleteness (missing luminous mass tracers), and the poorly determined relation between mass and luminosity. The impact of redshift distortion corrections is analysed in the context of MAK and we check the importance of edge and finite-volume effects on the reconstructed velocities. Using three mock catalogues with different average densities, we also study the effect of cosmic variance. In particular, one of them presents the same global features as found in observational catalogues that extend to 80 h,1 Mpc scales. We give recipes, checked using the aforementioned mock catalogues, to handle these particular observational effects, after having introduced them into the mock catalogues so as to quantitatively mimic the most densely sampled currently available galaxy catalogue of the nearby Universe. Once biases have been taken care of, the typical resulting error in reconstructed velocities is typically about a quarter of the overall velocity dispersion, and without significant bias. We finally model our reconstruction errors to propose an improved Bayesian approach to measure ,m in an unbiased way by comparing the reconstructed velocities to the measured ones in distance space, even though they may be plagued by large errors. We show that, in the context of observational data, it is possible to build a nearly unbiased estimator of ,m using MAK reconstruction. [source] Rhodolith bed diversity in the Gulf of California: the importance of rhodolith structure and consequences of disturbanceAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2003D.L. Steller Abstract 1.Rhodolith beds, unattached coralline reefs, support a high diversity and abundance of marine species from both hard and soft benthos. We used surveys in multiple shallow (3,20 m) beds in the Gulf of California to (1) examine seasonal patterns in associated floral and faunal diversity and abundance, (2) compare differences in faunal associations between rhodolith beds and adjacent sedimentary habitats, (3) examine the importance of complexity of rhodolith structure to community structure, and (4) estimate the impact of anthropogenic disturbance on rhodoliths and associated species. 2.Macroalgal richness was seasonal, and beds supported higher richness in winter (to 36 species) than summer (6,7 species), primarily due to foliose red algae. Strong seasonal variation in the abundance of dominant cover organisms was due to a shift from macroalgae and mat-forming colonial invertebrate species to microalgae. 3.The community in a rhodolith bed of high-density thalli (El Coyote average ,11000 thalli/ m,2) had higher richness (52 versus 30 species) and abundance of epibenthic and crypto- and in-faunal species compared with an adjacent sand community. Species diversity and abundance was particularly high for unique cryptofaunal organisms associated with rhodolith interstices. Cryptofauna reached average densities of 14.4 organisms/ cm,3 rhodolith, the majority of which were crustaceans, polychaetes and cnidarians along with rhodolith-specific chitons. 4.Results from sampling across a range of rhodolith morphs in the El Requeson bed (with lower average cryptofaunal densities of 2.3 organisms/ cm,3) revealed that the total organisms supported by a rhodolith significantly increased with both complexity (branching density) and space available (thallus volume). These data suggest that reducing the population size structure, structural complexity and cover of living rhodoliths could decrease species richness and abundance. 5.While disturbance is a natural feature of these free-living beds, increased anthropogenic disturbance from trawling, anchoring and changes in water quality can directly impact the bed community through substrate alteration. Commercial fishing threatens rhodolith beds in the Gulf of California by decreasing rhodolith size and increasing sedimentation and burial rates. In addition to reducing direct destruction, conservation efforts should also focus on decreasing practices that breakdown thalli. Copyright © 2003 John Wiley & Sons, Ltd. [source] Ni Catalyst Coating on Fecralloy® Microchanneled Foils and Testing for Methane Steam ReformingCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2010N. de Miguel Abstract The procedure following the washcoating of three different Ni catalyst systems (MgO, Al2O3, and CeO2/Al2O3 supported) on pretreated Fecralloy® microchanneled foils under controlled milling times and viscosities of the slurries is described. The activity of the prepared coatings is also presented. Four different series of coated foils were prepared: one per each catalyst system, keeping constant the average particle size on 5 ,m, and one extra series to study the effect of reducing the average particle size of the MgO-supported catalyst system to 3 ,m. For each coating, scanning electron microscopy pictures were taken and specific surface areas and average densities of the catalyst layers were estimated. Finally, each series of coated foils was stacked and tested in a microreactor for the methane steam reforming (MSR) reaction under different conditions. [source] 2143: Corneal keratocyte population after laser subepithelial keratectomy (LASEK) with mitomycin C (MMC): 3 months vs 15 months comparisonACTA OPHTHALMOLOGICA, Issue 2010P CANADAS SUAREZ Purpose To study corneal keratocyte population after LASEK with mitomycin C (MMC) 15 months vs 3 months after surgery Methods Sixty eyes were included in this study, all of them treated with LASEK with intraoperative 0.02% MMC, divided into 2 groups. 32 eyes had LASEK performed 3 months before, versus 28 in the 15 months post-op group. Keratocyte density was examined by using confocal microscopy in the anterior, mid and posterior stroma in both groups, and the mean density was compared with a control group of healthy eyes Results Keratocyte density in the anterior stroma was 16993,75+ 8001,7 cells/mm3 and 18529,1 + 2917,7 cells/mm3(p=0,3) in the 3 months and in the 15 months groups respectively, in the mid stroma it was 30783,3+ 9300 cells/mm3 in the 3 months and 20754,7 + 3615,3 cells/mm3 in the 15 months groups (p= 0,0001) and 30286,75+ 8321 cells/mm3and 19994+ 3085,9 cells/mm3 (p= 0,0001) in the posterior stroma in the 3 months and in the 15 months groups respectively. The comparison between the average densities through the whole cornea showed statistically significant difference between the 3 months vs 15 months group and 3 months vs normals, but it was not statistically significant different between 15 months vs normals Conclusion The changes in the corneal keratocyte population after LASEK + MMC seen in the early post-op, seem to change towards the normal values 15 months after the procedure. [source] Biological Sustainability of Live Shearing of Vicuña in PeruCONSERVATION BIOLOGY, Issue 1 2007CATHERINE TERESA SAHLEY Andes; conservación basada en comunidades; Vicugna vicugna Abstract:,The vicuña's (Vicugna vicugna) fiber is highly valued as an export product that is made into luxury fabric and clothing. The price of fiber in 2004 was $566/kg, which makes the fiber a potentially important source of income for Andean agropastoral communities and serves as an incentive to allow vicuña grazing on high-elevation Andean landscapes. It is presumed that a shorn vicuña has little value for poachers, so shearing vicuñas could serve as a disincentive to poaching. Thus, the supply of vicuña fiber may be sustainable if it is procured through live shearing, which should serve as a powerful conservation tool. We evaluated the effects of capture and shearing on the demography of vicuña in one site located in the Salinas Aguada Blanca Reserve, Arequipa, Peru, where vicuñas were captured and shorn in spring and then returned to the wild. We conducted fixed-width line-transect censuses from 1997 to 2003 of this population. We compared the proportion of young born to females that were shorn versus females that were unshorn for the 3 years in which shearing occurred. We evaluated the effect of capture and shearing on proportion of young born to shorn and unshorn females at a second site, Picotani, Puno. The wild population in Arequipa that underwent capture and shearing showed a steady increase in total population and average density between 1997 and 2003. No significant difference was found between the proportion of young per female for shorn and unshorn females at either site. We conclude that in spring, capture and live shearing of vicuñas can be biologically sustainable. Further research is needed to determine whether shearing during winter months is biologically sustainable. Resumen:,La fibra de vicuña (Vicugna vicugna) tiene gran valor como un producto de exportación que es transformado en tela y ropa de lujo. El precio de la fibra en 2004 era de $566/kg, lo que hace que la fibra sea una fuente de ingreso potencialmente importante para comunidades agropastoriles Andinas y servir como un incentivo para permitir el pastoreo de vicuñas en paisajes Andinos elevados. Se presume que una vicuña trasquilada tiene poco valor para cazadores furtivos, por lo que el trasquilado de vicuñas pudiera servir como un desincentivo para la caza furtiva. Por lo tanto, el abastecimiento de fibra de vicuña puede ser sustentable si se obtiene del trasquilado de animales vivos, y el trasquilado de animales vivos debería ser una poderosa herramienta de conservación. Evaluamos los efectos de la captura y trasquilado sobre la demografía de vicuñas en un sitio localizado en la Reserva Salinas Aguada Blanca, Arequipa, Perú, donde las vicuñas fueron capturadas y trasquiladas en primavera y liberadas. Realizamos censos de esta población en transectos lineales de ancho fijo de 1997 a 2003. Comparamos la proporción de crías de hembras trasquiladas con las de hembras no trasquiladas durante los 3 años en que ocurrió el trasquilado. Evaluamos el efecto de la captura y trasquilado sobre la proporción de crías de hembras trasquiladas y no trasquiladas en un segundo sitio, Picotani, Puno. La población silvestre en Arequipa que fue capturada y trasquilada mostró un incremento constante en la población total y la densidad promedio entre 1997 y 2003. No se encontró diferencia significativa entre la proporción de crías por hembra para hembras trasquiladas y no trasquiladas en ningún sitio. Concluimos que en la primavera, la captura y trasquilado de vicuñas vivas puede ser biológicamente sostenible. Se requiere más investigación para determinar si el trasquilado durante el invierno es biológicamente sostenible. [source] The Distribution of Follicular Units in the Chinese Scalp: Implications for Reconstruction of Natural-Appearing Hairlines in OrientalsDERMATOLOGIC SURGERY, Issue 6 2002Ren-Yeu Tsai MD background. Follicular transplantation using hair in its naturally occurring groups, called follicular units (FUs), has become the most popular technique in hair restoration surgery. Recently follicular transplantation was performed with a qualitative and quantitative concept to achieve the best clinical result. The characteristics and distribution of FUs are well studied in Caucasians and widely applied in hair transplantation surgery. objective. In order to understand the normal distribution of FUs in the Chinese scalp, we counted the number of hairs and FUs in normal Chinese scalp to provide general information for surgical planning and design in bald Chinese patients. methods. A total of 50 normal and 50 bald Chinese adults were enrolled to count the hairs on their scalp. One hundred bald patients receiving hairline reconstruction were also prospectively quantitatively evaluated. results. In normal Chinese scalp, an average 71.78 FUs/cm2 and 137.08 hairs/cm2 were calculated with a follicular density of 1.91 hairs/FU. Two-hair FUs are the predominate group (50.29%). In bald patients, an average of 68.07 FUs/cm2 was found, which was less than that of the occipital scalp in normal nonbald patients. In reconstruction of the frontal hairline, a total of 700,1000 FUs were implanted with an average density of 30 FUs/cm2. conclusion. We found the average number of FUs (0.72 FU/mm2) was less than that in Caucasian patients (1 FU/mm2). The average density of 30 FUs/cm2 implanted was suitable to reconstruct a natural frontal hairline in bald Chinese patients, which can achieve about 40% of normal hair density. Our results could provide the hair surgeon with general information about hair distribution on the Chinese scalp for surgical planning and design in their patients. [source] Correlation between population dynamics of mosquito larvae and their habitat qualitiesENTOMOLOGICAL RESEARCH, Issue 4 2008Lalit Mohan RANJEETA Abstract Surveillance of anopheline and culicine larvae was conducted fortnightly to determine population composition and density at seven sites in the area of the Mathura Refinery, Mathura, India during 2005,2006. The correlation between population of the vectors and their habitat quality was established. Temperature (0.978 and 0.85°C), pH (0.99 and 0.95), conductivity (0.98 and 0.98 mho) and calcium ion hardness (0.978 and 0.85 p.p.m.) were positively correlated with the populations of both larval species. In contrast, the correlation coefficients between the parameters total hardness, magnesium ion hardness, biochemical oxygen demand and chemical oxygen demand varied with the larval species. The anopheline larval population was dominant over the culicine population in the surveillance area. The distribution of anopheline mosquito larvae during the study period was found to be constant, and the average density of anopheline and culicine larvae was 84.70 and 15.30%, respectively, across all seven sites. Thus, the study demonstrated spatial and temporal population differences of mosquito larvae with respect to environmental factors, including water quality. [source] Distribution of glycine receptor subunits on primate retinal ganglion cells: a quantitative analysisEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2000Bin Lin Abstract This study investigates the distribution of inhibitory neurotransmitter receptors on sensory neurons. Ganglion cells in the retina of a New World monkey, the common marmoset Callithrix jacchus, were injected with Lucifer yellow and Neurobiotin and subsequently processed with antibodies against one (,1), or against all subunits, of the glycine receptor, or against the anchoring protein gephyrin. Immunoreactive (IR) puncta representing glycine receptor or gephyrin clusters were found on the proximal and the distal dendrites of all ganglion cell types investigated. For both parasol and midget cells, the density of receptor clusters was greater on distal than proximal dendrites for all antibodies tested. In parasol cells the average density for the ,1 subunit of the glycine receptor was 0.087 IR puncta/µm of dendrite, and for all subunits it was 0.119 IR puncta/µm of dendrite. Thus, the majority of glycine receptors on parasol cells contain the ,1 subunit. For parasol cells, we estimated an average of 1.5 glycinergic synapses/100 µm2 dendritic membrane on proximal dendrites and about 9.4 glycinergic synapses/100 µm2 on distal dendrites. The segregation of receptors to the distal dendrites appears to be a common feature of inhibitory neurotransmitter input to parasol and midget cells, and might be associated with the receptive field surround mechanism. [source] Modelling the hydraulic preferences of benthic macroinvertebrates in small European streamsFRESHWATER BIOLOGY, Issue 1 2007SYLVAIN DOLÉDEC Summary 1. Relating processes occurring at a local scale to the natural variability of ecosystems at a larger scale requires the design of predictive models both to orientate stream management and to predict the effects of larger scale disturbances such as climate changes. Our study contributes to this effort by providing detailed models of the hydraulic preferences of 151 invertebrate taxa, mostly identified at the species level. We used an extensive data set comprising 580 invertebrate samples collected using a Surber net from nine sites of second and third order streams during one, two or three surveys at each site. We used nested non-linear mixed models to relate taxon local densities to bed shear stresses estimated from FliesswasserStammTisch hemisphere numbers. 2. An average model by taxon, i.e. independent from surveys, globally explained 25% of the density variations of taxa within surveys. A quadratic relationship existed between the average preferences and the niche breadth of taxa, indicating that taxa preferring extreme hemisphere numbers had a reduced hydraulic niche breadth. A more complete model, where taxa preferences vary across surveys, globally explained 38% of the variation of taxa densities within surveys. Variations in preferences across surveys were weak for taxa preferring extreme hemisphere numbers. 3. There was a significant taxonomic effect on preferences computed from the complete model. By contrast, season, site, average hemisphere number within a survey and average density of taxa within a survey used as covariates did not consistently explain shifts in taxon hydraulic preferences across surveys. 4. The average hydraulic preferences of taxa obtained from the extensive data set were well correlated to those obtained from two additional independent data sets collected in other regions. The consistency of taxon preferences across regions supports the use of regional preference curves for estimating the impact of river management on invertebrate communities. By contrast, the hydraulic niche breadths of taxa computed from the different data sets were not related. [source] Lithosphere structure of Europe and Northern Atlantic from regional three-dimensional gravity modellingGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2002T. P. Yegorova Summary Large-scale 3D gravity modelling using data averaged on a 1° grid has been performed for the whole European continent and part of the Northern Atlantic. The model consists of two regional layers of variable thickness,the sediments and the crystalline crust, bounded by reliable seismic horizons,the ,seismic' basement and the Moho surface. Inner heterogeneity of the model layers was taken into account in the form of lateral variation of average density depending on the type of geotectonic unit. Density parametrization of the layers was made using correlation functions between velocity and density. For sediments, sediment consolidation with depth was taken into account. Offshore a sea water layer was included in the model. As a result of the modelling, gravity effects of the whole model and its layers were calculated. Along with the gravity modelling an estimation of isostatic equilibrium state has been carried out for the whole model as well as for its separate units. Residual gravity anomalies, obtained by subtracting the gravity effect of the crust from the observed field, reach some hundred mGal (10,5 m s,2) in amplitude; they are mainly caused by density heterogeneities in the upper mantle. A mantle origin of the residual anomalies is substantiated by their correlation with the upper-mantle heterogeneities revealed by both seismological and geothermal studies. Regarding the character of the mantle gravity anomalies, type of isostatic compensation, crustal structure, age and supposed type of endogenic regime, a classification of main geotectonic units of the continent was made. As a result of the modelling a clear division of the continent into two large blocks,Precambrian East-European platform (EEP) and Variscan Western Europe,has been confirmed by their specific mantle gravity anomalies (0 ÷ 50 × 10,5 m s,2 and ,100 ÷,150 × 10,5 m s,2 correspondingly). This division coincides with the Tornquist,Teisseyre Zone (TTZ), marked by a gradient zone of mantle anomalies. In the central part of the EEP (over the Russian plate) an extensive positive mantle anomaly, probably indicating a core of ancient consolidation of the EEP, has been distinguished. To the west and to the east of this anomaly positive mantle anomalies occur, which coincide with a deep suture zone (TTZ) and an orogenic belt (the Urals). Positive mantle anomalies of the Alps, the Adriatic plate and the Calabrian Arc, correlating well with both high-velocity domains in the upper mantle and reduced temperatures at the subcrustal layer, are caused by thickened lithosphere below these structures. Negative mantle anomalies, revealed in the Western Mediterranean Basin and in the Pannonian Basin, are the result of thermal expansion of the asthenosphere shallowing to near-Moho depths below these basins. [source] Storage, patterns and controls of soil organic carbon in the Tibetan grasslandsGLOBAL CHANGE BIOLOGY, Issue 7 2008YUANHE YANG Abstract The soils of the Qinghai-Tibetan Plateau store a large amount of organic carbon, but the magnitude, spatial patterns and environmental controls of the storage are little investigated. In this study, using data of soil organic carbon (SOC) in 405 profiles collected from 135 sites across the plateau and a satellite-based dataset of enhanced vegetation index (EVI) during 2001,2004, we estimated storage and spatial patterns of SOC in the alpine grasslands. We also explored the relationships between SOC density (soil carbon storage per area) and climatic variables and soil texture. Our results indicated that SOC storage in the top 1 m in the alpine grasslands was estimated at 7.4 Pg C (1 Pg=1015 g), with an average density of 6.5 kg m,2. The density of SOC decreased from the southeastern to the northwestern areas, corresponding to the precipitation gradient. The SOC density increased significantly with soil moisture, clay and silt content, but weakly with mean annual temperature. These variables could together explain about 72% of total variation in SOC density, of which 54% was attributed to soil moisture, suggesting a key role of soil moisture in shaping spatial patterns of SOC density in the alpine grasslands. [source] Spatial patterns of kangaroo density across the South Australian pastoral zone over 26 years: aggregation during drought and suggestions of long distance movementJOURNAL OF APPLIED ECOLOGY, Issue 5 2007ANTHONY R. POPLE Summary 1Wildlife surveys usually focus on estimating population size, and management actions such as commercial harvesting, culling and poison baiting are referenced commonly to population size alone, without taking into account the way in which those animals are distributed. This paper outlines how point-based aerial survey data can be converted to continuous density surfaces using spatial analysis techniques. Using this approach, we describe and explore the spatial patterns of density of two species of kangaroos in an area exceeding 200 000 km2 in South Australia over a 26-year period. 2Densities of red and western grey kangaroos were estimated in 2 km2 segments along aerial survey transect lines, yielding point density estimates. Universal kriging provided an unbiased interpolation of these data using the spatial autocorrelation structure described by the semi-variogram. The Getis statistic identified clusters of high and low kangaroo density. 3Considerable year-to-year variation in the spatial patterns of kangaroo density was observed. In many cases, annual rates of increase over large areas were too high to be explained by vital rates alone, implying immigration from surrounding areas. These large shifts in distribution were occasionally to areas that had received better rainfall than the surrounding areas. For both species, there was no obvious local spatial autocorrelation pattern or clustering of kangaroo density beyond that described by average density and the present set of management regions, suggesting the latter are appropriate divisions for harvest management. 4Data for both species fitted the power law relationship extremely well. During dry times, red kangaroos, but not western grey kangaroos, were more aggregated, supporting past ground observations at a fine spatial scale. 5Synthesis and applications. Kriged density surfaces enable estimation of kangaroo density on individual properties, which are the management units at which harvest quotas or culling approvals are allocated. These estimates will be marked improvements over systematic sampling estimates when sampling intensity is low. Predictions of shifts in kangaroo distribution using rainfall or satellite imagery will allow more accurate allocation of harvest quotas. Similarly, predictions of more even kangaroo dispersion following high rainfall will allow managers to anticipate downturns in harvest rate. [source] Ultrahigh-pressure eclogite transformed from mafic granulite in the Dabie orogen, east-central ChinaJOURNAL OF METAMORPHIC GEOLOGY, Issue 9 2007Y.-C. LIU Abstract Although ultrahigh-pressure (UHP) metamorphic rocks are present in many collisional orogenic belts, almost all exposed UHP metamorphic rocks are subducted upper or felsic lower continental crust with minor mafic boudins. Eclogites formed by subduction of mafic lower continental crust have not been identified yet. Here an eclogite occurrence that formed during subduction of the mafic lower continental crust in the Dabie orogen, east-central China is reported. At least four generations of metamorphic mineral assemblages can be discerned: (i) hypersthene + plagioclase ± garnet; (ii) omphacite + garnet + rutile + quartz; (iii) symplectite stage of garnet + diopside + hypersthene + ilmenite + plagioclase; (iv) amphibole + plagioclase + magnetite, which correspond to four metamorphic stages: (a) an early granulite facies, (b) eclogite facies, (c) retrograde metamorphism of high-pressure granulite facies and (d) retrograde metamorphism of amphibolite facies. Mineral inclusion assemblages and cathodoluminescence images show that zircon is characterized by distinctive domains of core and a thin overgrowth rim. The zircon core domains are classified into two types: the first is igneous with clear oscillatory zonation ± apatite and quartz inclusions; and the second is metamorphic containing a granulite facies mineral assemblage of garnet, hypersthene and plagioclase (andesine). The zircon rims contain garnet, omphacite and rutile inclusions, indicating a metamorphic overgrowth at eclogite facies. The almost identical ages of the two types of core domains (magmatic = 791 ± 9 Ma and granulite facies metamorphic zircon = 794 ± 10 Ma), and the Triassic age (212 ± 10 Ma) of eclogitic facies metamorphic overgrowth zircon rim are interpreted as indicating that the protolith of the eclogite is mafic granulite that originated from underplating of mantle-derived magma onto the base of continental crust during the Neoproterozoic (c. 800 Ma) and then subducted during the Triassic, experiencing UHP eclogite facies metamorphism at mantle depths. The new finding has two-fold significance: (i) voluminous mafic lower continental crust can increase the average density of subducted continental lithosphere, thus promoting its deep subduction; (ii) because of the current absence of mafic lower continental crust in the Dabie orogen, delamination or recycling of subducted mafic lower continental crust can be inferred as the geochemical cause for the mantle heterogeneity and the unusually evolved crustal composition. [source] Genetic loci influencing natural variations in femoral bone morphometry in mice,JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 4 2001Thomas A. Drake This study identifies genetic loci affecting femoral bone length and width measures in mature mice. Sixteen month old female F2 progeny of a C57BL/6J and DBA/2J intercross were examined for femur length and width of the femoral head, intertrochanteric region and three locations of the diaphysis using digitized images of femur radiographs obtained in the anterior-posterior and lateral projections. A genome wide linkage map was constructed using microsatellite markers at an average density of 20 cM, and quantitative trait locus analysis used to identify regions of the genome showing linkage with the traits measured. Femur length showed significant linkage with loci on proximal chromosome 3 (lod 6.1), and suggestive linkage with a locus on chromosome 14. A major locus on mid-chromosome 7 controlled width of the diaphysis (lod 6.8). Other loci were identified on chromosomes 2 and 4. Width at the intertrochanteric region had suggestive linkage with loci on chromosomes 6 and 19. No loci were found with linkage for width of the femoral head. Candidate genes related to bone development or metabolism are present at most of these loci. These findings show that genetic regulation of femoral bone morphology is complex, and are consistent with the distinct biologic processes that control longitudinal and lateral growth of the femur. © 2001 Orthopaedic Research Society. Punlished by Elsevier Science Ltd. All rights reserved. [source] Physiological and behavioral responses of Bathynerita naticoidea (Gastropoda: Neritidae) and Methanoaricia dendrobranchiata (Polychaeta: Orbiniidae) to hypersaline conditions at a brine pool cold seepMARINE ECOLOGY, Issue 1 2007Ahna L. Van Gaest Abstract Bathynerita naticoidea (Gastropoda: Neritidae) and Methanoaricia dendrobranchiata (Polychaeta: Orbiniidae) are two of the most abundant invertebrates associated with cold-seep mussel beds in the Gulf of Mexico. At the methane seep known as Brine Pool NR-1 (27 °43.415 N, 91 °16.756 W; 650 m depth), which is surrounded by a broad band of mussels (Bathymodiolus childressi), these species have distinctly different patterns of abundance, with the gastropod being found mostly at the outer edge of the mussel bed (average density in November 2003: 817 individuals·m,2 in outer zone, 20·m,2 in inner zone) and the polychaete being found almost exclusively near the inner edge (average density in November 2003: 3155 individuals·m,2 in inner zone, 0·m,2 in outer zone), adjacent to the brine pool itself. The salinity of the brine pool exceeds 120, so we hypothesized that M. dendrobranchiata should be more tolerant of high salinities than B. naticoidea. The opposite proved to be true. The gastropods were capable of withstanding salinities at least as high as 85, whereas the polychaetes died at salinities higher than 75. Both species were osmoconformers over the range of salinities (35,75) tested. Behavioral responses of B. naticoidea to salinities of 50, 60, and 70 were investigated in inverted vertical haloclines. Gastropods generally did not enter water of salinity greater than 60, but tolerated short periods at 60. Behavioral avoidance of brine should limit the vertical distribution of B. naticoidea in the inner zone to the top 2.5,5 cm of the mussel bed. Behavior is also a likely (though unproven) mechanism for controlling horizontal distribution of this species across the mussel bed. Methanoaricia dendrobranchiata can tolerate short excursions into the brine, but probably avoids hypersaline conditions by aggregating on the tops of the mussels. [source] Constrained by available raptor hosts and islands: density-dependent reproductive success in red-breasted geeseOIKOS, Issue 3 2003Jouke Prop In this paper we aim to explain the distribution of red-breasted geese Branta ruficollis over different nesting habitats. To be safe from land predators red-breasted goose colonies were restricted to i) islands on rivers, ii) cliffs with peregrine falcons Falco peregrinus, and iii) the close proximity of snowy owl Nyctea scandiaca and rough-legged buzzard Buteo lagopus nests. Among years nest site availability varied by fluctuations in numbers of owls and buzzards in association with cycles in lemming abundance, but the total number of goose nests found in the study area did not vary. The distribution of geese, in combination with data on reproductive success, suggested a despotic mechanism: at cliffs, goose numbers were constant among years with an invariably high reproductive success, whereas large fluctuations in numbers on islands coincided with opposite trends in success. Apparently, geese nesting with owls or buzzards moved to the few islands present in the study area during years when these birds of prey were absent. Consequently, in such years the average density of geese on islands was more than twice as high as at cliff colonies (5.4 and 2.3 pairs per ha of foraging habitat, respectively). Colony size at cliffs may have been restricted by territorial behaviour of the geese, though there is evidence that, additionally, the host falcons also limited the number of nesting geese. Apparently rare in closely related species, we observed a negative density-dependent effect on reproductive success during the nest phase, and attribute this to limited food resources, reinforced by the high frequency of territorial interactions. This leads to the conclusion that, in addition to predation pressure, nesting density is an important agent in the link between lemming cycles and goose breeding success. [source] Average protein density is a molecular-weight-dependent functionPROTEIN SCIENCE, Issue 10 2004Hannes Fischer Abstract The mass density of proteins is a relevant basic biophysical quantity. It is also a useful input parameter, for example, for three-dimensional structure determination by protein crystallography and studies of protein oligomers in solution by analytic ultracentrifugation. We have performed a critical analysis of published, theoretical, and experimental investigations about this issue and concluded that the average density of proteins is not a constant as often assumed. For proteins with a molecular weight below 20 kDa, the average density exhibits a positive deviation that increases for decreasing molecular weight. A simple molecular-weight-depending function is proposed that provides a more accurate estimate of the average protein density. [source] Regional specialization of the Ganglion cell density in the retina of the Ostrich (Struthio camelus)ANIMAL SCIENCE JOURNAL, Issue 1 2010Mohammad L. RAHMAN ABSTRACT In this study, retinal whole-mount specimens were prepared and stained with 0.1% cresyl violet for the ganglion cell study in the Ostrich (Struthio camelus). The total number, distribution, and size of these cells were determined in different retinal regions. The mean total number of ganglion cells (three retinas) was 1 435 052 with an average density of 652 cells/mm2. The temporo , nasal area of the retina with high cell density were identified with the peak of 7525 cells/mm2 in the central area. The size of most ganglion cells ranged from 113,403 µm2, with smaller cells predominating along the temporo-nasal streak above the optic disc and larger cells comprising more of the peripheral regions. The average thickness of the retina was 196 µm. The central area was the thickest area (268.6 µm), whereas the peripheral area was the thinnest area. Thus, the specialization of ganglion cell densities, their sizes and the thickness of the retina support the notion that the conduction of visual information towards the brain from all regions of the retina is not uniform, and suggests that the temporo , nasal streak is the fine quality area for vision in ostriches. [source] Survival in rectal cancer is predicted by T cell infiltration of tumour-associated lymphoid nodulesCLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 1 2010T. P. W. McMullen Summary Lymphoid nodules are a normal component of the mucosa of the rectum, but little is known about their function and whether they contribute to the host immune response in malignancy. In rectal cancer specimens from patients with local (n = 18), regional (n = 12) and distant (n = 10) disease, we quantified T cell (CD3, CD25) and dendritic cell (CD1a, CD83) levels at the tumour margin as well as within tumour-associated lymphoid nodules. In normal tissue CD3+, but not CD25+, T cells are concentrated at high levels within lymphoid nodules, with significantly fewer cells found in surrounding normal mucosa (P = 0·001). Mature (CD83), but not immature (CD1a), dendritic cells in normal tissue are also found clustered almost exclusively within lymphoid nodules (P = < 0·0001). In rectal tumours, both CD3+ T cells (P = 0·004) and CD83+ dendritic cells (P = 0·0001) are also localized preferentially within tumour-associated lymphoid nodules. However, when comparing tumour specimens to normal rectal tissue, the average density of CD3+ T cells (P = 0·0005) and CD83+ dendritic cells (P = 0·0006) in tumour-associated lymphoid nodules was significantly less than that seen in lymphoid nodules in normal mucosa. Interestingly, regardless of where quantified, T cell and dendritic cell levels did not depend upon the stage of disease. Increased CD3+ T cell infiltration of tumour-associated lymphoid nodules predicted improved survival, independent of stage (P = 0·05). Other T cell (CD25) markers and different levels of CD1a+ or CD83+ dendritic cells did not predict survival. Tumour-associated lymphoid nodules, enriched in dendritic cells and T cells, may be an important site for antigen presentation and increased T cell infiltration may be a marker for improved survival. [source] | |||||||||||||||||||||||||||||||