Number Of Subdivisions Research Articles

The angioarchitecture of the rat mandibular joint synovium

The synovium (or synovial membrane) lines all intra-articular surfaces of synovial joints except for the articulating surfaces. This study describes the angioarchitecture of the synovium of the adult rat temporomandibular joint using microvascular corrosion casts and scanning electron microscopy. To corroborate findings, India ink-injected, thick-sectioned specimens (200 μm) and haematoxylin and eosin-stained tissue sections (7 μm) were analysed. Rostrally, the synovial membrane was fed by several layers of vessels branching towards the superficial lining of highly convoluted capillary loops. Arterioles were rare, and venules organized in large plexuses. The membrane thinned out in the caudal direction. Ville were present on the surface. They were flat, with a core of two parallel linear feeder vessels, one arteriole and one venule, which were interconnected by capillary loops. At the periphery of the articulating surfaces, the vessels of the synovial layer were flatter. Caudally, the synovial membrane of the richly vascularized retrodiscal pad showed many synovial folds. Feeder vessels were directed rostrally and branched in all directions. The number of subdivisions depended on the size of the synovial fold. Again, venules were organized in plexuses and lining capillaries were convoluted. The densely capillarized synovial membrane with its folds and villi is considered well adapted to serve synovial fluid production and joint dynamics.

Degree reduction of Bezier curves and its error analysis

AbstractThe error analysis of an algorithm for generating an approximation of degree n − 1 to an nth degree Bézier curve is presented. The algorithm is based on observations of the geometric properties of Bézier curves which allow the development of detailed error analysis. By combining subdivision with a degree reduction algorithm, a piecewise approximation can be generated, which is within some preset error tolerance of the original curve. The number of subdivisions required can be determined a priori and a piecewise approximation of degree m can be generated by iterating the scheme.

The error analysis for degree reduction of Bézier curves

The error analysis of Farin's and Forrest's algorithms for generating an approximation of degree n − 1 to an n th degree Bézier curve is presented. Algorithms are based on observations of the geometric properties of the Bézier curve which allow the development of detailed error analysis. By combining subdivision with a degree reduction algorithm, a piecewise approximation can be generated, which is within some preset error tolerance of the original curve. The number of subdivisions required can be determined a priori and a piecewise approximation of degree m can be generated by iterating the scheme.

Channel routing independent of length subdivision

Flood routing in a given reach of a prismatic channel is the process of deriving the downstream outflow hydrograph from a known inflow hydrograph at the upstream end of the channel reach. The process can be carried out by solving the basic St.‐Venant (S‐V) equation numerically or by using a lumped model, also called a hydrologic or black‐box model, which requires calibration with observed data. The model should also be capable of reproducing the flow hydrograph at one or more intermediate points along the channel reach. This requires that at least one of the model parameters be proportional to the length of the channel reach. Another desired property of the routing model is that the outflow hydrograph produced at the downstream end of a channel reach be the same when the model is applied to the entire reach, as one unit, or when the model is applied to a number of sections or subdivisions of the channel reach in series, using the outflow of one section as inflow to the next section. The resulting outflow hydrograph at the downstream end of the reach should thus be independent of the number or lengths of the subdivisions. The above desired properties of the routing model impose certain conditions on the model or, if the model is linear, on its impulse response function (IRF). The conditions are derived in this paper and applied to two models: the linear channel model and the diffusion analogy model.

About the Order of Divergence of the Major Bacterial Taxa During Evolution

An evolutionary tree, reconstructed from 1232 bacterial small ribosomal subunit RNA sequences by a distance method, reflects the existence of 11 divisions and a number of subdivisions originally recognized by Woese and collaborators. However, the order of divergence that gave rise to these taxa remains indeterminate and the division of Gram positives and relatives does not behave as a monophyletic taxon. Analysis of the data by a novel approach led to a preferred order of divergence for 10 out of 16 tree nodes, but the Gram positives still behaved as biphyletic.

Layout Construction: A Case Study In Algorithm Engineering

<p>We design a system for generating newspaper layout proposals. The input to the system consists of editorial information (text, pictures, etc) and style information (non-editorial information that specifies the aesthetic appearance of a layout). We consider the automation of layout construction to pose two main problems. One problem consists in optimizing the layout with respect to the constraints and preferences specified in the style information. Another problem consists in finding a representation of the style information that both supports its use in the combinatorial optimization and supports its modification through high level user interaction and automatic inference from a database of examples.</p><p> </p><p>We propose a solution that combines <em> heuristic search, randomization </em> and <em> neural networks.</em> We have implemented a first version based on the <var> bisection </var> strategy -- a page is bisected recursively until the number of sub-divisions matches the number of articles to be placed.</p>

AN OBJECTWE TEST FOR HYDROLOGIC SCALE1

ABSTRACT: Improving the reliability of parametric hydrologic models (sometimes called cenceptual rainfall‐runoff models) in the continuous simulation of runoff from ungaged catchments has been frustrated by difficulties in estimating model parameters from catchment characteristics. An underlying problem is that these models use parameters to represent catchments as a whole, whereas data on catchment characteristics are collected at multiple field locations and are difficult to transform into one measure of collective impact. Subdividing the catchment and calibrating a stochastic parametric model to estimate distributions for the parameters that covered the range of observed streamflow values was found to improve the simulations. This paper presents an optimization of the amount of subdivision to use in simulation with a version of the Stanford Watershed Model using available climatological data. The calibration process assumes that catchment heterogeneity introduces errors that can be reduced by calibrating parameters as spatial distributions rather than single values. Calibrations for three diverse small gaged catchments located in California and in Virginia found the optimal number of subdivisions to range from 4 to 25 and the optimal scale to range from 0.3 to 2.1 mi2.

Trends and periodicities in sub-divisional rainfall

The monthly and annual rainfall data for 35 meteorological sub-divisions for the 87-year period (1901-1987) have been used to study the trends and periodicities of monsoon and annual rainfall series. A number of distribution-free statistical tests have been applied to the rainfall series for testing non-randomness. Comparison of the decadewise means with the mean of the whole period showed that, for the country as a whole, the annual rainfall indicated four different climatic periods -two periods of above normal rainfall from 1960-1965 and from 1975 onwards and two periods of below normal rainfall from 1901-1915 and 1965-1975 whereas the monsoon rainfall showed two different climatic periods-a period of below normal rainfall from 1901-1920 and a period of above normal rainfall from 1920 onwards. The series were also subjected to low-passfilters which showed the presence of significant long term trend for a few sub-divisions. The power spectrum analysis for the annual and monthly rainfall series for a large number of sub-divisions showed significant periodicities of 2. 1-3.6 years, which correspond to the frequency range of the QBO. In addition, periodicities of 5.1 to 10.0 years and 19.3 years or more were also significant for a number of sub-divisions.

Phylogenetic changes in the connections of the lateral preglomerular nucleus in ostariophysan teleosts: a pluralistic view of brain evolution.

The connections of the lateral preglomerular nucleus were examined with the fluorescent tracer DiI in a cyprinid, a characin, a catfish and a gymnotoid species. In all of these taxa the lateral preglomerular nucleus receives inputs from the torus semicircularis and projects to the telencephalon. Cytoarchitectural and topological data further support the hypothesis that the lateral preglomerular nucleus is homologous among the species examined. A cladistic analysis of species differences, however, reveals that some connections of the lateral preglomerular nucleus have changed dramatically during the course of evolution. Some of the cell groups that are interconnected with the lateral preglomerular nucleus have increased in size, while others have decreased. Increases in the number of subdivisions of cell groups are frequently associated with size increases, but they may also be associated with size decreases. Some of the connections between cell groups have increased in strength, whereas others have decreased in strength, but these connectional changes bear no simple relationship to phylogenetic changes in the size of the cell groups. Phylogenetic increases in the number of subdivisions within a cell group may be associated with selective gains of connections, but they may be associated also with selective losses of connections or with no major changes in connections. Furthermore, several cell groups and connections appear to have evolved 'de novo', whereas others have disappeared during the course of evolution. Finally, the individual cell groups within this system of interconnected nuclei have changed largely independently of one another. These findings establish that brain evolution is not dominated by a single type of phylogenetic change.

Calculation of Total Conveyance in Natural Channels

The evaluation of total conveyance using the summation approach over section elements is reviewed for one-dimensional, uniform, steady state flow in simple concave channels. The subdivision of a concave section into elements, the introduction of a lateral velocity gradient, the neglect of lateral shear between the elements, and the computation of the nonlinear conveyance as a linear summation of its components all contribute to the overestimation of total conveyance computed by the summation approach. The overestimation is quantified for six selected section shapes. The degree of overestimation is a function of section shape and increases with the number of section elements used in the summation. Based on the integral form of the summation approach, rectangular and trapezoidal section with width-to-depth (W/D) ratios above 20 have a computed total conveyance value within 5% above the value for the undivided section. For W/D ratios less than five, the summation approach produces significantly higher total conveyance values for five of the six section shapes. In this low range of W/D ratios, the summation approach should be avoided. In cases where the summation approach is required, the overestimation can be controlled by minimizing the number of section subdivisions. Differences in total conveyance computed by the summation approach are illustrated for a natural section.

Subdivisions and neuron types of the nucleus of the solitary tract that project to the parabrachial nucleus in the hamster

The solitary nuclear complex (NST) consists of a number of subdivisions that differ in their cytoarchitectonic features as well as in the amounts of inputs they receive from lingual afferent axons. In this study horseradish peroxidase (HRP) was injected into the parabrachial nucleus (PBN) of the hamster to determine which of these subdivisions contain cells that project to the pons. In the rostral, gustatory division of the NST, the rostral central subdivision contains the greatest number of labelled pontine-projection neurons. The rostral lateral subdivision contains moderate numbers of labelled cells; progressively fewer labelled cells are in the ventral, medial, and dorsal subdivisions. In the caudal, general viscerosensory division of the NST, the caudal central subdivision contains the majority of labelled cells, although fewer than its rostral counterpart. Progressively fewer cells are labelled in the medial, laminar, ventrolateral, and lateral subdivisions; none in the dorsolateral subdivision. Small horseradish peroxidase injections into the pons revealed that cells of the rostral central and rostral lateral subdivisions of the NST project to the medial subdivision of the PBN, predominantly to caudal and ventral parts of the subdivision. Cells of the caudal central and medial subdivisions of the NST project to the central lateral subdivision of the PBN, predominantly to intermediate and rostral-dorsal parts of the subdivision. Outside the NST, cells in the spinal trigeminal nucleus and parvicellular reticular formation were also labelled after PBN injections. Within the rostral central and rostral lateral (gustatory) subdivisions of the NST at least two types of neurons, distinguished on the basis of dendritic and cell body morphology, were labelled after HRP injections that included the medial PBN. Elongate cells have ovoid-fusiform somata and dendrites oriented in the mediolateral plane parallel to primary afferent axons entering from the solitary tract. Stellate cells have triangular or polygonal cell bodies and three to five dendrites oriented in all directions, although one or two often extend mediolaterally. These results indicate that cytoarchitectonic subdivisions of the NST are distinguished by their efferent ascending connections. For each subdivision within the rostral, gustatory NST there is a correlation between the density of lingual inputs it receives and the density of pontine-projection neurons it contains.(ABSTRACT TRUNCATED AT 400 WORDS)

The object-oriented systems life cycle

In software engineering, the traditional description of the software life cycle is based on an underlying model, commonly referred to as the “waterfall” model (e.g., [4]). This model initially atte...

CHEMICAL COMMUNICATION IN INSECT COMMUNITIES: A GUIDE TO INSECT PHEROMONES WITH SPECIAL EMPHASIS ON SOCIAL INSECTS

SUMMARY Chemical communication plays an important part in the lives of insects, and particularly in lives of those that live in groups or social organizations. Chemicals which are used in communication in the general sense are called semiochemicals, and there are a number of subdivisions recognized under this title. Pheromones are a category of semiochemicals which are used for communication between individuals of the same species. Pheromones are in turn subdivided into primer and releaser pheromones. The former produce a relatively long‐lasting physiological change in the receiver, and the latter stimulate the receiver to some immediate behavioural response. Far more is known about releaser pheromones at present because they are easier to study. Nine categories of releaser pheromone are recognized here, used by both social and non‐social insects. Sex pheromones are widely used to bring the sexes together for mating, and they have been extensively studied in Lepidoptera. Invitation pheromones, encouraging the species to feed or oviposit at an explored site, are not extensively known. Aggregation pheromones are designed to bring individuals together into groups which may be temporary in sub‐social insects, or permanent in social insects. Dispersal or spacing pheromones are used by other species to reduce intraspecific competition for scarce resources. Alarm pheromones are a broad and sometimes unclearly defined group which communicate alarm or attack, chiefly in colonial species. Trail pheromones, applied to a surface by an individual, to be followed by another, are confined to Hymenoptera, Isoptera and a few Lepidoptera as far as is known. Territorial and home range pheromones may be widely distributed, but as yet few of them have been recognized. Surface and funeral pheromones are even less well known. Surface pheromones may play a large part in species or colony recognition. We can expect the number and complexity of pheromones to be much greater in social insects, a part of the subject which until now has received relatively less attention. As our understanding of the subject grows we may expect other categories to be added to this list.

Historic Cataloging Costs, Issues, and Trends

The length of LC cataloging cards in number of characters increased 24.5 percent between 1956 and 1981, the number of entries 130.2 percent, the number of fields 96.9 percent, and the number of subject heading subdivisions 156.2 percent. There is a trend toward longer and more complex cataloging copy and a small countertrend toward less than AACR2 cataloging. Most academic libraries, 69.2 percent, are unable to state what their cataloging costs are. Since 1876 the wholesale commodity price index has increased 729 percent, the price of gold (another measure of inflation) 1,590 percent, and the cost of cataloging for large libraries from $0.40 per volume to $17.17 per volume, or 4,292 percent. Since 1896 librarians' annual salaries have increased from $607 to $28,533 or 4,700 percent. Cataloging costs have increased faster than the rate of inflation, but more slowly than the rate of salary increases.

Degree reduction of Bézier curves

An algorithm for generating an ( n − 1)st degree approximation to an nth degree Bézier curve is presented. The method is based on minimax approximation techniques which allow the development of a detailed error analysis. By combining subdivision with the degree reduction algorithm, a piecewise defined approximation can be generated, which is within some preset error tolerance of the original curve. The number of subdivisions required can be determined a priori and by iterating the scheme, a piecewise degree d approximation can be generated.

A Thermodynamic Design Simulation for Stirling Cycle Machines Using a Lagrangian Formulation

This paper describes a one-dimensional simulation of the Stirling cycle machine. A Lagrangian coordinate system is used in conjunction with an implicit solution scheme. The detailed formulation of the conservation equations is set out, including the heat transfer and fluid friction correlations used. The regenerator model includes the use of a spline function to represent the axial temperature distribution. The means of increasing the rate at which the solution attains its final steady state value is outlined. The choice of working fluid subdivision size and number is investigated along with the equation integration time increment. It is shown that optimum values exist for both. Finally, a favourable comparison is made of predicted and experimental results for the pressure-time variations and heat transfers to and from the compression and expansion spaces of a heat pump. The problems of using air as the working fluid are discussed.

Excitation and response of piping systems

A piping system can be vibration excited by a number of sources that are a consequence of the flow of the internal fluid, the pumps, and other ancillary equipment of the system. The vibrational power induced in the pipe structure will be partly radiated as noise and partly transmitted through the isolators attaching the quiet piping system to the supporting structure. The transmission of this vibrational power to the supporting structure is investigated in this article using power flow and structural mobility methods. The approach that is developed here is not limited to isolated straight pipe sections but can be applied to a number of subsections joined together by components that can be represented by structural mobility terms. The results obtained can be useful towards the design of quiet piping systems. The influence of the different structural parameters of the pipe, isolators, and support structure can be clearly demonstrated.

Arterial segmentation and subsegmentation in the human spleen.

The segmental nature of the arterial tree of the human spleen was analyzed in 181 subjects of both sexes, who had died of various accidental causes. Based on the observation of the pattern of the terminal and polar splenic branches, selective arteriographs and corrosion casts, and taking account of the ideas reported in the literature, we proposed that the spleen is divided in arterial segments and subsegments. Segments are the territories corresponding to both the primary branches of the splenic artery (primary segments) and the polar arteries (polar segments). In 92.82% of the cases there are two primary segments and in 7.18% three primary segments. Associated to these, in 29.28% there is a superior polar segment, in 44.75% an inferior polar segment, and in 10.49% both superior and inferior polar segments are present. Thus, the number of segments varies from two to five. Occasionally, two or three inferior polar segments can be present. Subsegments are the territories corresponding to the extrasplenic subdivisions of the primary branches and the polar arteries. According to the number of arterial subdivisions, the subsegments can be of second, third, fourth, fifth or sixth order. The last branches of the splenic artery (penetrating arteries) are all subsegmentary in nature and supply hilar or polar subsegments. Anastomoses between extrasplenic branches of the splenic artery were observed in 19.89% of the cases. Sometimes, thin anastomotic bridges could be observed between arterial splenic compartments.

A taxonomic study of the "medicagoid" Trigonella (Leguminosae)

The medicagoid Trigonella are a cohesive group of Old World species of much closer affinity to Medicago than to Trigonella. A numerical examination indicated that these are appropriately placed in two sections, each with a number of perceivable subdivisions. A key and illustrations to the 23 species recognized in this study are presented.

A study of cell models: 2. The effect of time delay on the limiting forms of cascade and manifold cell model response functions

A simplified cell model was used to investigate the behavior of the impulse response function (IRF) of cell models incorporating time delay elements, as the number of subdivisions increases. The simplified model used in this study was a single branch model consisting of a number of equal cells arranged in sequence. Two cell models were studied, a cascade model and a manifold model. In this study the model representing each cell is modified by the addition of a delay element which is taken to be linearly proportional to the distance of its corresponding cell from the outlet. The limiting forms of the IRFs are derived for the two models using Laplace transforms; the cascade cell model IRF is found to converge to a rectangle regardless of the values of its parameters, while the manifold cell model IRF converges to a family of curves whose shapes depend quite sensitively on the values of the parameters chosen. The expression derived contains the exponential integral function, which has not been used before in surface hydrology. For some combinations of the parameters, the IRF has the classical (or intuitively expected) shape consisting of a steep rise and mild recession. For other values, the IRF is reminiscent of the kinematic wave solution to the overland flow equations, and some comparisons are made. The manifold cell model is found to hold promise as a suitably behaved alternative to the cascade cell model in the context of distributed surface runoff systems.