263 resultados para similarity


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Sound recordings and behavioural data were collected from four primate species of two genera (Macaca, Presbytis). Comparative analyses of structural and behavioural aspects of vocal communication revealed a high degree of intrageneric similarity but striking intergeneric differences. In the two macaque species (Macaca silenus, Macaca radiata), males and females shared the major part of the repertoire. In contrast, in the two langurs (Presbytis johnii, Presbytis entellus), many calls were exclusive to adult males. Striking differences between both species groups occurred with respect to age-specific patterns of vocal behaviour. The diversity of vocal behaviour was assessed from the number of different calls used and the proportion of each call in relation to total vocal output for a given age/sex class. In Macaca, diversity decreases with the age of the vocalizer, whereas in Presbytis the age of the vocalizer and the diversity of vocal behaviour are positively correlated. A comparison of the data of the two genera does not suggest any causal relationship between group composition (e.g. multi-male vs. one-male group) and communication system. Within each genus, interspecific differences in vocal behaviour can be explained by differences in social behaviour (e.g. group cohesion, intergroup relation, mating behaviour) and functional disparities. Possible factors responsible for the pronounced intergeneric differences in vocal behaviour between Macaca and Presbytis are discussed.

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l-Valyl-l-lysine hydrochloride, C11N3O3H23 HCl, rystallizes in the monoclinic space group P2, with a = 5.438(5), b = 14.188(5), c = 9.521(5) Å, β= 95.38(2)° and Z = 2. The crystal structure, solved by direct methods, refined to R = 0.036, using full matrix least-squares method. The peptide exists in a zwitterionic form, with the N atom of the lysine side-chain protonated. The two γ-carbons of the valine side-chain have positional disorder, giving rise to two conformations, χ111= -67.3 and 65.9°, one of which (65.9°) is sterically less favourable and has been found to be less popular amongst residues branching at β-C. The lysine side-chain has the geometry of g− tgt, not seen in crystal structures of the dipeptides reported so far. Interestingly, χ32 (63.6°) of lysine side-chain has a gauche+ conformation unlike in most of the other tructures, where it is trans. The neighbouring peptide molecules are hydrogen bonded in a head-to-tail fashion, a rather uncommon interaction in lysine peptide structures. The structure shows considerable similarity with that of l-Lys-l-Val HO in conformational angles and H-bond interactions [4].

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A cDNA clone has been isolated from a chicken liver library prepared against messenger RNA isolated after chronic estradiol-17β treatment. The clone, pP-450 IA - 61, has an insert of 900nt and the sequence shows high homology to CYPIA2 subfamily from four other species. A single injection of estradiol-17β to immature chicken results in a striking induction of mRNA hybridizing to labeled pP-450IA - 61. The probe also hybridizes to mRNA induced by 3 — methylcholanthrene in chicken. These results offer direct proof for the similarity in the mode of action at the transcriptional level of polyaromatic hydrocarbons and estrogenic compounds.

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Boundary-layer transition at different free-stream turbulence levels has been investigated using the particle-image velocimetry technique. The measurements show organized positive and negative fluctuations of the streamwise fluctuating velocity component, which resemble the forward and backward jet-like structures reported in the direct numerical simulation of bypass transition. These fluctuations are associated with unsteady streaky structures. Large inclined high shear-layer regions are also observed and the organized negative fluctuations are found to appear consistently with these inclined shear layers, along with highly inflectional instantaneous streamwise velocity profiles. These inflectional velocity profiles are similar to those in the ribbon-induced boundary-layer transition. An oscillating-inclined shear layer appears to be the turbulent spot-precursor. The measurements also enabled to compare the actual turbulent spot in bypass transition with the simulated one. A proper orthogonal decomposition analysis of the fluctuating velocity field is carried out. The dominant flow structures of the organized positive and negative fluctuations are captured by the first few eigenfunction modes carrying most of the fluctuating energy. The similarity in the dominant eigenfunctions at different Reynolds numbers suggests that the flow prevails its structural identity even in intermittent flows. This analysis also indicates the possibility of the existence of a spatio-temporal symmetry associated with a travelling wave in the flow.

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Biomimetics involves transfer from one or more biological examples to a technical system. This study addresses four questions. What are the essential steps in a biomimetic process? What is transferred? How can the transferred knowledge be structured in a way useful for biologists and engineers? Which guidelines can be given to support transfer in biomimetic design processes? In order to identify the essential steps involved in carrying out biomimetics, several procedures found in the literature were summarized, and four essential steps that are common across these procedures were identified. For identification of mechanisms for transfer, 20 biomimetic examples were collected and modeled according to a model. of causality called the SAPPhIRE model. These examples were then analyzed for identifying the underlying similarity between each biological and corresponding analogue technical system. Based on the SAPPhIRE model, four levels of abstraction at which transfer takes place were identified. Taking into account similarity, the biomimetic examples were assigned to the appropriate levels of abstraction of transfer. Based on the essential steps and the levels of transfer, guidelines for supporting transfer in biomimetic design were proposed and evaluated using design experiments. The 20 biological and analogue technical systems that were analyzed were similar in the physical effects used and at the most abstract levels of description of their functionality, but they were the least similar at the lowest levels of abstraction: the parts involved. Transfer most often was carried out at the physical effect level of abstraction. Compared to a generic set of guidelines based on the literature, the proposed guidelines improved design performance by about 60%. Further, the SAPPhIRE model turned out to be a useful representation for modeling complex biological systems and their functionality. Databases of biological systems, which are structured using the SAPPhIRE model, have the potential to aid biomimetic concept generation.

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The formation and decomposition of quasicrystalline and crystalline phases in as-rapidly solidified and annealed commercial AISI 2024 aluminum alloy containing 2 wt% Li have been investigated by detailed transmission electron microscopy, including a combination of bright field and dark field imaging, selected area diffraction pattern analysis and energy dispersive X-ray microanalysis. The microstructure of as-melt spun 2024-2Li consists of alpha-Al cells, containing small coherent delta' precipitates, and particles or a continuous network of the icosahedral phase at the cell boundaries. After annealing at 300-degrees-C, the intercellular particles of the icosahedral phase coarsen progressively and assume a more faceted shape; after annealing at 400-degrees-C, particles of the decagonal and crystalline O phases precipitate heterogeneously on preexisting particles of the icosahedral phase; and after annealling at 500-degrees-C, the icosahedral and decagonal phases dissolve completely, and small particles of the crystalline O phase remain together with newly precipitated plates of the T1 phase. The icosahedral phase in melt spun and melt spun/annealed 2024-2Li belongs to the Al6CuLi3 class of icosahedral phases, with a quasilattice constant of 0.51 nm, a stoichiometry of (Al, Si)6(Cu, Mn, Fe) (Li, Mg)3 and an average composition of Al-24.1 at.% Cu-6.4 at.% Mg-1.7 at.% Si-0.3 at.% Mn-0.5 at.% Fe as-melt spun and Al-21.9 at.% Cu-6.3 at.% Mg-1.0 at.% Si-0.5 at.% Fe as-heat-treated. The decagonal phase in melt spun/annealed 2024-2Li belongs to the Al4Mn class of decagonal phases, with a periodicity of 1.23 nm along the 10-fold symmetry axis, a stoichiometry of Al3(Cu, Mn, Fe) and an average composition of Al-10.3 at.% Cu-13.8 at.% Mn-2.3 at.% Fe. The crystalline O phase in melt spun/annealed 2024-2Li has an orthorhombic structure with lattice parameters of a = 2.24 nm, b = 2.35 nm and c = 1.23 nm, a stoichiometry of Al3(Cu, Mn, Fe) and an average composition of Al-11.0 at.% Cu-14.8 at.% Mn-3.9 at.% Fe. Detailed analysis of selected area diffraction patterns shows a close similarity between the icosahedral, decagonal and crystalline O phases in melt spun and melt spun/annealed 2024-2Li. In particular, the decagonal phase and crystalline O phases have a similar composition, and exhibit an orientation relationship which can be expressed as: [GRAPHICS] suggesting that the orthorhombic O phase is an approximant structure for the decagonal phase.

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The polyamines spermine, spermidine, putrescine, cadaverine, etc. have been implicated in a variety of cellular functions. However, details of their mode of interaction with other ubiquitous biomolecules is not known. We have solved a few structures of polyamine-amino acid complexes to understand the nature and mode of their interactions. Here we report the structure of a complex of putrescine with DL-glutamic acid. Comparison of the structure with the structure of putrescine-L-glutamic acid complex reveals the high degree of similarity in the mode of interaction in the two complexes. Despite the presence of a centre of symmetry in the present case, the arrangement of molecules is strikingly similar to the L-glutamic acid complex.

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The polyamines spermine, spermidine, putrescine, cadaverine, etc. have been implicated in a variety of cellular functions. However, details of their mode of interaction with other ubiquitous biomolecules is not known. We have solved a few structures of polyamine-amino acid complexes to understand the nature and mode of their interactions. Here we report the structure of a complex of putrescine with DL-glutamic acid. Comparison of the structure with the structure of putrescine-L-glutamic acid complex reveals the high degree of similarity in the mode of interaction in the two complexes. Despite the presence of a centre of symmetry in the present case, the arrangement of molecules is strikingly similar to the L-glutamic acid complex.

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The paper deals with the flow and heat-transfer problem of a steady axisymmetric laminar incompressible boundary layer swirling flow of a fluid through a conical hydrocyclone. The implicit finitedifference scheme is used to solve the partial differential equations governing the flow. The effect of swirl is found to be more pronounced on the longitudinal skin friction than on the tangential skin friction and heat transfer. The skin friction and heat transfer increase with swirl or with longitudinal distance. Swirl also gives rise to velocity overshoot in the longitudinal velocity profiles and the magnitude of the velocity overshoot increases as the swirl parameter increases. The results are found to be in good agreement with those of the local nonsimilarity and momentum integral methods but they differ appreciably from those of the local similarity method except for the longitudinal skin friction which is fairly in good agreement with that of the local similarity method.Die Arbeit beschäftigt sich mit der Strömung und dem Wärmeübergang in einem konischen Zyklon unter der Voraussetzung stationärer, achsensymmetrischer, laminarer, inkompressibler Grenzschichtströmung. Ein implizites Differenzenverfahren wird benutzt, um die partiellen Differentialgleichungen zu lösen. Der Einfluß des Dralls ist besonders ausgeprägt auf die longitudinale Komponente der Oberflächenreibung, weniger dagegen bei der tangentialen Komponente und beim Wärmeübergang. Die Oberflächenreibung und der Wärmeübergang nehmen zu mit dem Drall, sowie mit dem longitudinalen Abstand. Der Drall erzeugt ein Überschießen der Geschwindigkeit in der longitudinalen Abstand. Der Drall erzeugt ein Überschießen der Geschwindigkeit in der Längsrichtung. Die Größe des Überschusses nimmt mit wachsendem Drallparameter zu. Die Resultate stimmen gut mit den Ergebnissen der Theorie der lokalen Nichtähnlichkeit und der Impulsintegralmethode überein. Dagegen weichen sie mit Ausnahme der longitudinalen Komponente der Oberflächenreibung beträchtlich von den Resultaten der Theorie der lokalen Ähnlichkeit ab.

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An integrodifferential formulation for the equation governing the Alfvén waves in inhomogeneous magnetic fields is shown to be similar to the polyvibrating equation of Mangeron. Exploiting this similarity, a time‐dependent solution for smooth initial conditions is constructed. The important feature of this solution is that it separates the parts giving the Alfvén wave oscillations of each layer of plasma and the interaction of these oscillations representing the phase mixing.

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A specific radioimmunoassay procedure was developed to monitor the plasma concentrations of thiamin-binding protein, a minor yolk constituent of the chicken egg. By using this sensitive assay, the kinetics of oestrogen-induced elaboration of this specific protein in immature chicks was investigated. After a single injection of the steroid hormone, with an initial lag period of 4–5h the thiamin-binding protein rapidly accumulated in the plasma, attaining peak concentrations around 75h and declining thereafter. A 4-fold amplification of the response was noticed during the secondary stimulation, and this increased to 9-fold during the tertiary stimulation with the steroid hormone. The magnitude of the response was dependent on the hormone dose, and the initial latent period and the duration of the ascending phase of induction were unchanged for the hormonal doses tested during both the primary and secondary stimulations. The circulatory half-life of the protein was 6h as calculated from the measurement of the rate of disappearance of the exogenously administered 125I-labelled protein. Simultaneous administration of progesterone, dihydrotestosterone or corticosterone did not alter the pattern of induction. On the other hand, hyperthyroidism markedly decreased the oestrogenic response, whereas propylthiouracil-induced hypothyroidism had the opposite effect. The anti-oestrogen E- and Z-clomiphene citrates, administered 30min before oestrogen, effectively blocked the hormonal induction. a-Amanitin and cycloheximide administered along with or shortly after the sex steroid severely curtailed the protein elaboration. A comparison of the kinetics of induction of thiamin- and riboflavin-binding proteins by oestrogen revealed that, beneath an apparent similarity, a clear-cut difference exists between the two vitamin-binding proteins, particularly with regard to hormonal dose-dependent sensitivity of induction and the half-life in circulation. The steroid-mediated elaboration of the two yolk proteins thus appears to be not strictly co-ordinated, despite several common regulatory features underlying their induction.

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Clustering is a process of partitioning a given set of patterns into meaningful groups. The clustering process can be viewed as consisting of the following three phases: (i) feature selection phase, (ii) classification phase, and (iii) description generation phase. Conventional clustering algorithms implicitly use knowledge about the clustering environment to a large extent in the feature selection phase. This reduces the need for the environmental knowledge in the remaining two phases, permitting the usage of simple numerical measure of similarity in the classification phase. Conceptual clustering algorithms proposed by Michalski and Stepp [IEEE Trans. PAMI, PAMI-5, 396–410 (1983)] and Stepp and Michalski [Artif. Intell., pp. 43–69 (1986)] make use of the knowledge about the clustering environment in the form of a set of predefined concepts to compute the conceptual cohesiveness during the classification phase. Michalski and Stepp [IEEE Trans. PAMI, PAMI-5, 396–410 (1983)] have argued that the results obtained with the conceptual clustering algorithms are superior to conventional methods of numerical classification. However, this claim was not supported by the experimental results obtained by Dale [IEEE Trans. PAMI, PAMI-7, 241–244 (1985)]. In this paper a theoretical framework, based on an intuitively appealing set of axioms, is developed to characterize the equivalence between the conceptual clustering and conventional clustering. In other words, it is shown that any classification obtained using conceptual clustering can also be obtained using conventional clustering and vice versa.

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In this work, an analytical model is proposed for fatigue crack propagation in plain concrete based on population growth exponential law and in conjunction with principles of dimensional analysis and self-similarity. This model takes into account parameters such as loading history, fracture toughness, crack length, loading ratio and structural size. The predicted results are compared with experimental crack growth data for constant and variable amplitude loading and are found to capture the size effect apart from showing a good agreement. Using this model, a sensitivity analysis is carried out to study the effect of various parameters that influence fatigue failure. (C) 2010 Elsevier Ltd. All rights reserved.

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The nonsimilar non-Darcy mixed convection flow about a heated horizontal surface in a saturated porous medium has been studied when the surface temperature is a power function of distance (Tw = T∞ ± Axλ). The analysis is performed for the cases of parallel and stagnation flows with favourable induced pressure gradient. The partial differential equations governing the flow have been solved numerically using the Keller box method. The heat transfer is enhanced due to the buoyancy parameter and wall temperature, but the non-Darcy parameter reduces it. For non-Darcy flow, the similarity solution exists only for the case of parallel flow.

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Conformational studies have been carried out on the X-cis-Pro tripeptide system (a system of three linked peptide units, in the trans-cis-trans configuration) using energy minimization techniques. For X, residues Gly, L-Ala, D-Ala and L-Pro have been used. The energy minima have been classified into different groups based upon the conformational similarity. There are 15, 20, 18 and 6 minima that are possible for the four cases respectively and these fall into 11 different groups. A study of these minima shows that, (i) some minima contain hydrogen bonds - either 4-->1 or 1-->2 type, (ii) the low energy minima qualify themselves as bend conformations, (iii) cis' and trans' conformations are possible for the prolyl residue as also the C(gamma)-endo and C(gamma)-exo puckerings, and (iv) for Pro-cis-Pro, cis' at the first prolyl residue is ruled out, due to the high energy. The available crystal structure data on proteins and peptides, containing cis-Pro segment have been examined with a view to find the minima that occur in solid state. The data from protein show that they fall under two groups. The conformation at X in X-cis-Pro is near extended when it is a non-glycyl residue. In both peptides and proteins there exists a preference for trans' conformation at prolyl residue over cis' when X is a non-glycyl residue. The minima obtained can be useful in modelling studies.