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Structural Composition (structural + composition)
Selected AbstractsStructural composition and sediment transfer in a composite cirque glacier: Glacier de St. Sorlin, FranceEARTH SURFACE PROCESSES AND LANDFORMS, Issue 13 2008Sam Roberson Abstract This paper considers the links between structure, sediment transport and sediment delivery at Glacier de St. Sorlin, France. Sediment transported by the glacier is concentrated at flow-unit boundaries as medial moraines, controlled by the position of bedrock outcrops in the accumulation area. Rockfall entrained within primary stratification is tightly folded at flow-unit boundaries under high cumulative strains and laterally compressive stress. High cumulative strains and laterally compressive stresses lead to the development of longitudinal foliation from primary stratification. Folding elevates subglacial sediments into foliation-parallel debris ridges, which are exposed in the ablation area. Crevasses and shear planes within the glacier have little control on sediment transport. Debris stripes in the proglacial area are morphologically similar to foliation-parallel debris ridges; however, they are not structurally controlled, but formed by fluvial erosion. The conclusion of this study is that at Glacier de St. Sorlin proglacial sediment-landform associations are subjected to intense syn- and post-depositional modification by high melt-water discharges, hence their composition does not reflect that of sediments melting out at the terminus. The action of melt water limits the potential of the sedimentary record to be used to constrain numerical models of past glacier dynamics in debris-poor glacierized Alpine catchments. Copyright © 2008 John Wiley & Sons, Ltd. [source] Structural composition of ,I - and ,II -proteinsPROTEIN SCIENCE, Issue 2 2003Narasimha Sreerama Abstract Circular dichroism spectra of proteins are sensitive to protein secondary structure. The CD spectra of ,-rich proteins are similar to those of model ,-helices, but ,-rich proteins exhibit CD spectra that are reminiscent of CD spectra of either model ,-sheets or unordered polypeptides. The existence of these two types of CD spectra for ,-rich proteins form the basis for their classification as ,I - and ,II -proteins. Although the conformation of ,-sheets is largely responsible for the CD spectra of ,I -proteins, the source of ,II -protein CD, which resembles that of unordered polypeptides, is not completely understood. The CD spectra of unordered polypeptides are similar to that of the poly(Pro)II helix, and the poly(Pro)II-type (P2) structure forms a significant fraction of the unordered conformation in globular proteins. We have compared the ,-sheet and P2 structure contents in ,-rich proteins to understand the origin of ,II -protein CD. We find that ,II -proteins have a ratio of P2 to ,-sheet content greater than 0.4, whereas for ,I -proteins this ratio is less than 0.4. The ,-sheet content in ,I -proteins is generally higher than that in ,II -proteins. The origin of two classes of CD spectra for ,-rich proteins appears to lie in their relative ,-sheet and P2 structure contents. [source] Loss of phosphorus from soil in semi-arid northern Tanzania as a result of cropping: evidence from sequential extraction and 31P-NMR spectroscopyEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2000D. Solomon Summary In semi-arid northern Tanzania, the native woodland is being rapidly cleared and replaced by low input agriculture. This has resulted in pronounced environmental degradation, and in particular loss of phosphorus (P) from the soil. We have used sequential extraction and 31P-NMR to investigate the effects of land use changes, i.e. native woodland, degraded woodland, cultivation for 3 and 15 years and homestead fields where manure was applied, on the amount and structural composition of P in this soil. Clearing and continuous cultivation reduced both organic and inorganic P in the soil. The difference in the amount of organic P from the bulk soil of the fields cultivated for 3 and 15 years was not statistically significant (P <,0.05), suggesting that most of the depletion in organic P occurred during the first 3 years of cultivation. By contrast, in the homesteads, there was much organic and inorganic P in the soil. The 31P-NMR revealed that cultivation resulted in a 53% depletion of orthophosphate diester P, whereas only a 30% and 39% reduction of orthophosphate monoester P was found in the bulk soil after 3 and 15 years of cultivation, respectively. These results concur with the suggestion that diester P constitutes more easily mineralizable forms of organic P in soil than does monoester P. Our 31P-NMR also showed that 70% of the inorganic orthophosphate P was depleted from the coarse and fine sand separates as a result of cultivation. The influence of clearing and subsequent cropping on the amount and forms of P was more pronounced in the coarse and fine sand than in the silt and clay, stressing the importance of particle size and chemical properties such as organic matter and oxides in the availability of P in this soil. Our results show that the current low input agricultural practice is not sustainable, and that practices must be developed to combat the ongoing degradation of the soil. A combined use of available organic materials such as animal manure with the judicious use of inorganic fertilizers can replenish the soil's fertility. [source] Maternal sensitivity in interactions with three- and 12-month-old infants: Stability, structural composition, and developmental consequencesINFANT AND CHILD DEVELOPMENT, Issue 3 2004Arnold Lohaus This study addresses three topics related to the structural components of maternal sensitivity: (a) The stability of sensitivity over a nine-month period, (b) the predictability of maternal sensitivity assessed at 12 months from early parameters of parenting and (c) the relation between maternal sensitivity and developmental outcomes assessed at 12 months. Maternal sensitivity and its components (signal perception, correct interpretation, prompt, and appropriate reaction) were evaluated for 60 mother,infant-dyads when their infants were aged three and 12 months. Additional parameters of early parenting were maternal emotional warmth and behavioural contingency. Developmental outcome measures were the amount of infant crying and the quality of attachment at twelve months. The results showed close correlations between the sensitivity components suggesting a unidimensional structure for maternal sensitivity. The sensitivity assessments were significantly related to measures of maternal warmth. Stability of maternal sensitivity over time was, however, quite low. There was no relation between the early sensitivity assessments and later developmental outcomes, whereas there was a significant relation between the sensitivity parameters assessed at twelve months and developmental outcomes. The results indicate changes in the meaning of maternal sensitivity during infants' development. Copyright © 2004 John Wiley & Sons, Ltd. [source] Anticipating bipedalism: trabecular organization in the newborn iliumJOURNAL OF ANATOMY, Issue 6 2009Craig A. Cunningham Abstract Trabecular bone structural organization is considered to be predominantly influenced by localized temporal forces which act to maintain and remodel the trabecular architecture into a biomechanically optimal configuration. In the adult pelvis, the most significant remodelling forces are believed to be those generated during bipedal locomotion. However, during the fetal and neonatal period the pelvic complex is non-weight bearing and, as such, structural organization of iliac trabecular bone cannot reflect direct stance-related forces. In this study, micro-computed tomography scans from 28 neonatal ilia were analysed, using a whole bone approach, to investigate the trabecular characteristics present within specific volumes of interest relevant to density gradients highlighted in a previous radiographic study. Analysis of the structural indices bone volume fraction, trabecular thickness, trabecular spacing and trabecular number was carried out to quantitatively investigate structural composition. Quantification of the neonatal trabecular structure reinforced radiographic observations by highlighting regions of significant architectural form which grossly parallel architectural differences in the adult pattern but which have previously been attributed to stance-related forces. It is suggested that the seemingly organized rudimentary scaffold observed in the neonatal ilium may be attributable to other non-weight bearing anatomical interactions or even to a predetermined genetic blueprint. It must also be postulated that whilst the observed patterning may be indicative of a predetermined inherent template, early non-weight bearing and late stance-related locomotive influences may subsequently be superimposed upon this scaffolding and perhaps reinforced and likely remodelled at a later age. Ultimately, the analysis of this fundamental primary pattern has core implications for understanding the earliest changes in pelvic trabecular architecture and provides a baseline insight into future ontogenetic development and bipedal capabilities. [source] Causes and consequences of adaptive seasonal sex ratio variation in house sparrowsJOURNAL OF ANIMAL ECOLOGY, Issue 5 2006ARILD HUSBY Summary 1Here we examine how sex ratio variation in house sparrow broods interacts with other demographic traits and parental characteristics to improve the understanding of adaptive significance and demographic effects on variation in sex ratio. 2The sex ratio in complete broods did not deviate significantly from parity (54·9% males). 3There was sex-specific seasonal variation in the probability of recruitment. Male nestlings that hatched late in the breeding season had larger probability of surviving than early hatched males. 4An adaptive adjustment of sex ratio should favour production of an excess of males late in the breeding season. Accordingly, the proportion of male offspring increased throughout the breeding season. 5A significant nonlinear relationship was present between sex ratio and age of the female. However, there was no relationship between parental phenotype and standardized hatch day that could explain the observed seasonal change in sex ratio. 6The sex-specific number of offspring recruited by a pair to subsequent generations was closely related to the brood sex ratio. 7These results indicate an adaptive adjustment of sex ratio to seasonal variation in environmental conditions that affects the offspring fitness of the two sexes differently. Our results also suggest that such a sex ratio variation can strongly influence the demography and structural composition of small passerine populations. [source] THE DEGRADATION OF CHlTOSAN WITH THE AID OF LIPASE FROM RHIZOPUS JAPONICUS FOR THE PRODUCTION OF SOLUBLE CHlTOSANJOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2001SEUNG S. SHIN ABSTRACT Lipase from Rhizopus japonicus degraded chitosan resulting in soluble chitosan hydrolysates with molecular weight of about 30,50 kDa as shown by size exclusion chromatography. Optimal temperature for the hydrolysis of chitosan was 40C. The chitosan degradation products were fractionated stepwise according to their molecular weights by ultrafiltration with the filtration range of over 0.1 ,m, 0. l ,m to 30 kDa, 30 kDa to 10 kDa, 10 to 3 kDa, and 3 to 0.2 kDa. These fractions exhibited molecular weights of 50, 41, 41, 35, and 30 kDa, respectively. The molecular weights did not coincide with the pore size of filter membranes. Chitosan hydrolysate exhibited almost the same structural composition in IR spectra as chitosan flakes, except the peak of 1550 nm,1 that appeared to be the COO residue shifted from sodium acetate buffer to amine residue of chitosan. All fractions showed high solubility at neutral pH. The chitosan hydrolysates exhibiting molecular weights between 30 and 41 kDa were considered to be most suitable as a food additive or functional agent as demonstrated by sensory evaluation. [source] Changes in heathland vegetation under goat grazing: effects of breed and stocking rateAPPLIED VEGETATION SCIENCE, Issue 1 2010Rafael Celaya Abstract Questions: How are heathland vegetation dynamics affected by different goat grazing management? Location: Cantabrian heathlands in Illano, Asturias, northern Spain. Methods: During 4 years, vegetation dynamics (structural composition, canopy height and floristic diversity) were studied under three goat grazing treatments with three replicates: high stocking rate (11.7 goats ha,1) with a local Celtiberic breed, and high (15 goats ha,1) and low (6.7 goats ha,1) stocking rates with a commercial Cashmere breed. Results: The relative cover of woody plants, particularly heather species, decreased more while herbaceous cover increased more under local Celtiberic than under Cashmere breed grazing. Within Cashmere treatments, the cover and height of live shrubs decreased more and the herbaceous cover increased more under high than under low stocking rate. Redundancy analysis showed a significant effect of treatment × year interaction on floristic composition. Greater species richness was recorded under local goat grazing, but Shannon diversity index fell in the fourth year on these plots because of dominance by two grass species. Conclusions: Local Celtiberic goat grazing at such a high stocking rate (11.7 goats ha,1) hinders the development of sustainable systems on these heathlands, both in environmental and productive terms, owing to the limitations in soil fertility. Nevertheless, Celtiberic goats could be useful for controlling excessive shrub encroachment and reducing fire hazard. Cashmere goat grazing at high stocking rate promoted the highest Shannon diversity by generating a better balance between woody and herbaceous plants, while shrub dominance was not altered under the low stocking rate. [source] Composite bows at ed-Dur (Umm al-Qaiwain, U.A.E.)ARABIAN ARCHAEOLOGY AND EPIGRAPHY, Issue 2 2005An De Waele This article discusses seven bone fragments excavated during the second Belgian archaeological campaign at ed-Dur (tomb G.3831, area N). Rather than weaving implements, these objects are identified as the reinforcing bone laths of composite bows. Information on the composite bow in general,origins, structural composition and technical advantages,will be given. Additionally, the question of which types of composite bows could have been present at ed-Dur and what role these weapons could have played at the site are discussed. [source] Iridium Metal Thin Films and Patterned IrO2 Nanowires Deposited Using Iridium(I) Carbonyl PrecursorsCHEMICAL VAPOR DEPOSITION, Issue 7 2006Y.-L. Chen Abstract Highly volatile iridium(I) carbonyl complexes (1,5) with three anionic fluorinated chelates, namely ketoiminate, aminoalkoxide, or iminoalkoxide, have been synthesized and their physical properties relevant to CVD are evaluated. A single-crystal X-ray diffraction (XRD) study on Ir(CO)2(amakNMe2) (3) confirms a square-planar geometry with two cis-orientated carbonyl ligands. Metallic iridium, polycrystalline IrO2 thin films, or even patterned IrO2 nanowires are deposited using Ir(CO)2(hfdaNnPr) (5) as the CVD precursor. A systematic investigation of the deposition of IrO2 nanowires is conducted, showing a close correlation of observed crystallite morphology with applied system pressure, underlying growth surface, and deposition temperature. Of particular importance, tilted and vertically aligned IrO2 nanowires are obtained on LiTaO3(012) and LiNbO3(100) surfaces under a pressure of 30,Torr of oxygen at 425,°C. The morphology and structural composition of the IrO2 are confirmed by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and XRD analyses. [source] | ||||||||||||||||