Finer Subdivision Research Articles

New probabilistic strong seismic ground motion maps of Canada

AbstractNew probabilistic strong seismic ground motion maps of Canada are derived by applying the “Cornell-McGuire” method to 32 earthquake source zones in Canada and adjacent regions. Peak horizontal acceleration and peak horizontal velocity are mapped to depict strong ground motion in the frequency ranges near 5 Hz and near 1 Hz, respectively.Some earthquake source zones are well defined on the basis of both tectonics and average seismicity rates, but a lack of understanding of the near-field effects of the large earthquakes prohibits accurate estimates of ground motion in their vicinity. Some source zones have no known large-scale crustal features or zones of weakness that can explain the seismicity and must, therefore, be defined simply as concentrations of seismic activity with no geological or geophysical controls on the boundaries. Other source zones lack information on low-magnitude seismicity that would be representative of longer periods of time.A significant source of uncertainty in the ground motion estimates is introduced by the uncertainty in strong ground motion attenuation relations, particularly in the near-field of large earthquakes and particularly in eastern Canada where no strong motion data are available for earthquakes larger than magnitude 5. Valid estimates can be made of relative levels of probabilistic strong ground motion on a regional basis at moderate probabilities; however, the simple peak ground motion parameters are not sufficient for engineering design purposes in the immediate vicinity of large earthquakes.A comparison of the new probabilistic ground motion estimates at the Canada-United States border with equivalent estimates made in the United States reveals that peak acceleration contours match well in the British Columbia-Washington State, Yukon-Alaska, and Lake Ontario border regions. Canadian peak velocities are a factor of two higher near the British Columbia-Washington State border. Canadian peak accelerations are higher in the border regions of eastern Canada influenced by the Charlevoix zone, and in regions of the Alaska Panhandle-British Columbia border influenced by the active Queen Charlotte and Fairweather fault zones.The new ground motion estimates are used to produce new peak acceleration and peak velocity zoning maps to replace the 1970 (peak acceleration) zoning map in the National Building Code of Canada. The acceleration and velocity maps provide independent ground motion reference levels for small rigid structures and taller flexible structures, respectively. Compared to the 1970 map with four zones, the new maps with seven zones have a finer subdivision of zoning in moderate risk areas and additional zones in the high risk areas. A change in probability of exceedence from 0.01 per annum on the 1970 map to 10 per cent in 50 yr on the new maps, and the addition of velocity as a zoning parameter, have necessitated changes in the seismic design provisions. These revisions will be incorporated into the 1985 edition of the Code.

Cell determination boundaries as organizing regions for secondary embryonic fields

A model is proposed for pattern formation in secondary embryonic fields. It is stipulated that the boundaries, resulting from the primary embryonic organization of a developing organism, act as organizing regions for secondary embryonic fields, e.g., imaginal discs in insects. This boundary mechanism would allow very reliable pattern formation in the course of development: Primary positional information leads to cells of different determination, separated by sharp borders. At these borders, in turn, positional information would be generated for the next finer subdivision, and so on. This occurs if two or more differently determined cell types (e.g., compartments) cooperate for the production of a morphogenetic substance. A high concentration of the morphogen would appear at the common boundary of the cell types involved. Many experiments reported in the literature, for instance, the formation of duplicated and triplicated insect legs and the regeneration-duplication phenomenon of imaginal disc fragments can be explained under this assumption. The proposed boundary mechanism provides a molecularly feasible basis for the polar coordinate model.

The Role of Compartmentalization in the Activation of Particular Control Genes and in the Generation of Proximo-Distal Positional Information in Appendages

SYNOPSIS. A mechanism is proposed for the activation of particular genes during interpretation of positional information and during sequential addition of new structures during outgrowth. The primary event is assumed to be an alternation between two states. The alternation of anterior-posterior-anterior compartments in insects or bone-joint-bone in the chicken wing is assumed to be a trace of this primary subdivision into two alternative states. Each (or each second) transition from one state to the other causes a switch from one structure-controlling gene to the next. This enables a counting of alternations on the DNA-level and a high resolution in the corresponding activation of control genes. The model explains the formation of compartments and segmental specification in perfect register. The elements of the bithorax gene complex become understandable assuming this mechanism. It is shown further that such a “compartmentalization” can be used for the reproducible generation of subpatterns for the finer subdivision of a developing embryo. By “cooperation of compartments,” a cone-shaped morphogen distribution can be generated, accounting, e.g., for the circular arrangement of structures in the fate map of the leg disk of Drosophila. The most distal structures are formed at the intersection of compartments and distal transformation occurs whenever cells of all three or four major compartments are close to each other.

Dynamic analysis of frames by a two-level finite element method

A two-level finite element technique of constructing a frame super-element is introduced to reduce the computational efforts for solving large scale frame problems. The ordinary finite element method is used first to yield matrices for the beam members. Then the nodal displacements of all the nodes are related to those of a small number of selected joints (master nodes) in the frame by means of global finite element interpolating functions. Thus the order of the overall matrices is greatly reduced and the frame may be considered as a super-element to be connected to other elements by means of the master nodes. The accuracy of solution may be improved either with finer subdivision or by taking more master nodes inside each super-element.

Merging groups to maximize object partition comparison

The problem of objectively comparing two independently determined partitions ofN objects or variables is discussed. A similarity measure based on the simple matching coefficient is defined and related to previously suggested measures. The problem of merging groups in one partition to maximize this similarity measure is discussed and formulated as a mathematical programming problem; such an approach is useful for determining to what extent the groups in one partition merely represent a finer subdivision of the groups in the other partition. By exploiting the structure of the similarity measure, an efficient algorithm is developed to determine which groups (if any) should be merged to maximize partition similarity.

Antiparallel and parallel β-strands differ in amino acid residue preferences

A β-strand is a particular type of extended sequence of amino acid residues, an element of secondary structure of proteins. β-sheets are an assembly of strands, often bringing together parts of the protein which are separated along the backbone. As such, β-sheets are an element of tertiary structure. Parallel βP) and antiparallel (βA) arrangements of strands in a sheet differ in the hydrogen bond pattern between strands, as shown schematically in Fig. 1, and in the type of chain connectivity they allow: short reverse turn connections for βA and longer crossover connections for βP (refs 1–3). Most present secondary structure prediction methods (for reviews refs 4–6) use a four-state distinction of secondary structure: α-helix, β-strand or extended, reverse turn, and ‘random coil’ (everything else). With a data base of 30–40 different protein structures, the conformational preferences for all amino acid residues in these four states seem to have converged7. However, the steadily increasing data base of structurally known proteins makes a refinement of the four-state description feasible. Although more refined classifications of conformational states based on finer subdivisions of (φ,Ψ)-space have been made8,9, we prefer making distinctions based on structural environment. Using a novel definition of β-sheet structure in terms of the tertiary structure juxtaposition of strands, we have analysed residue contacts in known β-sheets and report here secondary structure preferences for the 20 amino acids, separately for antiparallel and parallel arrangements of strands. The distinction between the two arrangements results in strikingly different and sharpened sets of preference parameters, including some of the largest values reported so far for any substructure. These results point the way towards a basic improvement of secondary structure predictions by further distinction of secondary structure elements according to tertiary structure environment. Beyond secondary structure prediction, the different preferences for βA and βP may aid in predicting the tertiary interaction between strands.

Operations on Images Using Quad Trees

A quad tree for representing a picture is a tree in which successively deeper levels represent successively finer subdivisions of picture area. An algorithm is given for superposing N quad trees in time proportional to the total number of nodes in the trees. Warnock-type algorithms are then presented for building the quad tree for the picture of the boundary of a polygon, and for coloring the interior of such a polygon. These algorithms take O(v + p + q) time, where v is the number of polygon vertices, p is the polygon perimeter, and q is a resolution parameter. When the resolution q is fixed, these algorithms are asymptotically optimal.

The frequency spectra of solid neon and xenon

AbstractThe phonon frequencies of normal modes of vibration in solid neon and xenon are calculated at all the irreducible points of the first Brillouin zone with finer subdivisions (1000), using the unpaired‐elastic‐force model (EFM) recently developed. This is used to calculate the phonon densities of states. The calculated frequencies are compared in the highest symmetry directions [100], [110], and [111] with the recent available experimental data. It is observed that the theoretical results show a fairly good agreement with the neutron scattering measurements.

Frequency Spectra and Thermal Properties of Rare Gas Solids (Argon and Krypton)

AbstractThe unpaired elastic force model developed by the present authors is extended for studying the phonon frequencies of solid argon and krypton at all the irreducible points of the first Brillouin zone with finer subdivisions (1000). This is used to calculate the lattice heat capacities and Debye characteristic temperatures at different temperatures in the range 3 to 50 K. The comparison of theoretical values with the recently available experimental data reveals a fairly good agreement.

Bentonite Characteristics from Deposits near Rosalind, Alberta

AbstractTwo bentonite deposits having average thicknesses of 10 and 4 ft are exposed within nonmarine strata of Late Cretaceous age along the Battle River near Rosalind, Alberta. They are characterized by scarcity of >44 μm material and variable 44-2 μm and <2 μm contents. Material >44 μm in size in excess of 2 per cent is primarily attributable to secondary calcite, and <2 μm content may be related to the amount of 44-2 μm material that has altered diagenetically from volcanic glass to montmorillonite. Rhyodacite was the probable composition of the parent ash; therefore, the high iron content in one deposit is probably due to diagenesis. The blocking effect of iron on exchange sites can explain differences in exchangeable Na and Ca in different deposits. High exchangeable Na found in finer subdivisions of fractionated clay can be explained by increased purity of the bentonite.Multiple regression analysis of the analytical data shows that 48 per cent of the variation in yield (bbl/T.) of 15 centipoise drilling mud can be attributed to concomitant variation in seven interrelated compositional properties. Sequential analysis shows that <0·2 μm clay content is the most important contributor to variation in yield. The remaining variables (total clay content, exchangeable Na, exchangeable Ca + Mg, Fe2+ and Fe3+ contents, and CEC) contribute little additional precision to the regression analysis when <0·2 μm clay content is included in the equation.

Potential of opal phytoliths for use in paleoecological reconstruction

Opal phytoliths, inorganic biogenetic plant particles of microscopic size, were investigated to determine the level at which their varied morphology is taxonomically significant. Extraction methods for the isolation of these particles from living plants and from soils were developed to provide maximum preservation of morphological features while remaining simple, rapid, and inexpensive. Extracts were made and microscopically viewed from 30 live specimens, of which 16 were systematically typed in order to develop taxonomic guidelines for their identification in soils. Clear taxonomic differentiation was noted between and within major plant groups with considerable indication that more detailed investigation will yield finer subdivisions. Since opal phytoliths are reported to be a particularly durable fossil found in deposits as far back as Tertiary Age, it appears that opal phytolith analysis can provide paleobotanical information comparable to palynological data in many areas where pollen is absent. When used in conjunction with pollen where present, they should serve to confirm pollen data as well as provide additional botanical data not available in pollen studies.

Cyclicity in Upper Tertiary Basin-Margin Deposits of California Coast Ranges: ABSTRACT

Upper Tertiary marginal-marine sedimentary rocks of California are important reservoirs and have been studied extensively. However, they have been difficult to analyze in detail in terms of reservoir-scale genetic rock units because of the lack of a conceptual and fine stratigraphic framework for paleoecologic analysis and because sedimentation along the tectonically active Pacific Coast was dissimilar to that along the Gulf Coast where our modern depositional models have been largely generated. Detailed study of Pliocene and Miocene strata of the Coalinga region, integrating both macrofossil and lithologic evidence, indicates that basin-edge sediments were deposited during well-defined transgressive-regressive cycles. The thickness of strata deposited during the cycles and the proportion that was deposited during the transgressive phase of each cycle are proportional to the slope of the surface that was being transgressed. The Pliocene depositional slope in the Kettleman Hills area was very low (many cycles are represented by less than 100 ft of strata), and sedimentation occurred primarily during regression. In the Miocene examples, the depositional slope was greater, the cyclic units are thicker and probably represent longer periods, and much of the deposition occurred dur ng transgression. Cyclicity in the marginal marine strata provides finer subdivision and more precise correlation than has been possible by use of either fossils or lithology. It also provides the conceptual framework within which genetic rock units can be distinguished at reservoir scale. Positions of shoreline, loci of deltaic deposition, and environmental gradients within the shallow-marine deposits can be discriminated in the Kettleman Hills on layer maps representing subdivisions within individual cycles. End_of_Article - Last_Page 561------------

Maximum Attainable MTF for Rotationally Symmetric Lens Systems

Most optical systems have rotational symmetry. For such systems, we establish a method of finding (a) the maximum attainable modulation transfer function (MTF) at arbitrary frequency ω0; and (b) the required pupil function U(ω0; ρ). Physically, the latter are absorbing films in the pupil of diffraction-limited optics. The method of solution is numerical and iterative, based upon the Newton–Raphson algorithm. Solutions (a) and (b) are established at frequencies ω0 = 0.1, 0.2, ⋯, 0.9 (× optical cutoff). The computed (a) are correct to ±0.0001 over all ω0 indicated. Quantities (b) have an average error over each pupil of ±0.002 for frequencies ω0 ≤ 0.5. With 0.6 ≤ ω0 ≤ 0.9, the error is ±0.01. The curve of maximum MTF(ω0) seems sufficiently smooth to allow for accurate interpolation. Solutions (a) and (b) were also found over the finer subdivision ω0 = 0.05, 0.1, 0.15, ⋯, 0.8 with slightly less accuracy than above, in order to allow for interpolation of pupils U(ω0; ρ) over values ω0. This seems possible for 0.05 ≤ ω0 ≤ 0.40. The maximum MTF(ω0) shows appreciable gain (e.g., 8% at ω0 = 0.2) over the MTF for uncoated, diffraction-limited optics at all ω0 except in the intermediate region 0.4 ≤ ω0 ≤ 0.6. However, in the high-frequency band 0.5 ≤ ω0 ≤ 1.0, the maximum MTF(ω0) shows little gain over the MTF due to an uncoated, diffraction-limited pupil with the proper central obstruction. The light loss due to each U(ω0; ρ) may be measured by the total energy transmittance and the Strehl flux ratio. These are plotted against ω0, and indicate moderate light loss.

A difference method for solving boundary value problems of the axially symmetric equations of unsteady filtering

WE consider the equation ∂u ∂t = ∂ 2ϑ(u) ∂r 2 + 1 r ∂ϑ(u) ∂r , (1) where the function ϑ( u) is defined for values u ⩾ 0, and ϑ'( u) 〉 0 for u 〉 0, ϑ'(0) = 0; ▪ ϑ'( u) 〉 0 if α 〉 0. This equation describes the axially symmetric case of the phenomenon of unsteady filtering [1]. In [2, 3] the problems of the numerical solution of the one-dimensional equation ∂u ∂t = ∂ 2ϑ(u) ∂x 2 (1') for Cauchy's problem of the first and second boundary value problems are investigated. In [4] a different method is given for solving the multidimensional equation ∂u ∂t = ▪ ∂ ∂x α ( K α(u) ∂u ∂x α ) . In [6] by the change of variable x = ( r 2 ) 2 (this change of variable has been used previously, see for example [5]) equation (1) reduces to the form ∂u ∂t = ∂ ∂x ( x ∂ϑ(u) ∂x ) , (2) the finite difference approximation of (2) is constructed and the convergence of the solution u h , of the difference equation to the exact solution is proved, and as h → 0 for the first boundary value problem in the ranges [ x 0, 1] and [ x 0, ∞) (unfortunately in [6] some errors were made by the author). In this paper we consider problems of the numerical solution of equation (2) for the first and second boundary value problems on a non-uniform net. The results of this paper form an extension and generalization of the results of [6]. At the end of the paper results of illustrative calculations by the proposed scheme are given. The following fact is important when using the proposed scheme in practice. As already mentioned in [6] problems in which x 0 is small are of interest (both theoretical and practical). In this case the unknown function u( x, t) changes sharply for small x and this would appear to involve the necessity for a considerably finer subdivision of the net in this region. However, in the proposed scheme the expression x ∂ϑ(u) ∂x is approximated, which is well behaved, and in front of which in the chosen variables there is the operation of differentiation without a “troublesome” factor. This makes it possible to solve the problem for very small x 0, taking a practically completely acceptable h (see, for example. Fig. 3). The investigation of the equation considered leads to approximately the same plan as in the one-dimensional case in [2, 3]. However, the transition from an operator taking a pure second derivative on the right-hand side of (1') to an operator with variable coefficients in (1) and the consideration of difference schemes for variable steps required completely different methods of proof in a number of places. In those places where the proof of the properties considered is a natural generalization of the corresponding proof in [2, 3], it is omitted.

Matrix Formulation of Structural Stability Problems

A stability coefficient matrix is derived for use with the stiffness matrix in the deformation analysis of structures. This matrix allows the easy modification of the conventional beam stiffness matrix to include the effects of axial loads in the members and therefore gives a simple and rapid formulation of stability problems for columns and general frame structures. The matrix presented is approximate and the method gives an upper bound to the critical loading. However, the examples presented indicated excellent agreement with known exact results for both column and rigid frame critical loads, and the accuracy may be improved by a finer subdivision of the structure. The method is ideally suited for computers.

PATTERNS OF SPECIES DIVERSITY

Summary1. Species diversity is most simply measured by counting species. More complicated measures, which take into account the relative abundance of the species, have been derived from information theory or from parameters of statistical distributions fitted to the census data. The information theory formulae can also be used to measure habitat diversity and differences between communities or habitats. In this way, changes in the pattern of species diversity can be compared with changes in the environment.2. Small or remote islands and islands with uniform topography have fewer species than large or complex islands or islands nearer the source of colonization. For birds and some orders of insects it appears that the rate of colonization of new species is virtually balanced by the rate of extinction, so that the number of species has reached equilibrium. For other organisms, such as mammals, and for all organisms on the most remote islands, this equilibrium has probably not been reached and further increases in the fauna may be expected. The comparison of impoverished island faunas with the mainland faunas whence they were derived shows the effect of relaxed competition.3. Local variations in the species diversity of small uniform habitats can usually be predicted in terms of the structure and productivity of the habitat. Habitats of similar structure on islands and mainland often have similar species diversities; the impoverishment of the island is reflected in the fact that different habitats on the island have nearly the same species, while different habitats on the mainland have more different species. This is interpreted as evidence that uniform habitats are nearly saturated with species and that new species usually colonize by occupying different habitats from present species.4. The theory of competition and the facts of character displacement indicate that there is a limiting similarity to species which co‐exist within a habitat. Species more similar than this limiting value must occupy different habitats. According to the theory, this limiting value should be less where productivity is high, where family size is low and where the seasons are relatively uniform. It should also be less for pursuing hunters than for species which search for stationary prey.5. Total species diversities, from areas composed of many types of habitat, are usually, but not always, much greater in the tropics than in temperate regions. This is accomplished by a finer subdivision of habitats (habitat selection) more than by a marked increase in diversity within habitats. This total diversity may still be increasing and may have not reached saturation.

Facies Maps Based on the Megascopic Examination of Modern Sediments

ABSTRACT A procedure that allows 50-100 samples to be processed per day has been used successfully in mapping areal variations in organic matter, shell content, minimum size, maximum size, modal size, dominant sizes, and gross lithology of the modern nearshore sediments near Morehead City, North Carolina. Color values are estimated and used as semi-quantitative measures of organic matter. The shell content is estimated by comparison with a frequency estimation chart. The size properties of the non-shell material are determined by binocular microscope examination of small samples placed on a size comparison slide and in a dispersing solution in a glass caster. This size information is summarized by symbols which are plotted at the sample locations and are used to outline the natural sediment groupings. This procedure, although rapid and only semi-quantitative, provides for finer subdivisions of sand areas than with groupings based on sand-silt-clay ratios.

Wacke, Graywacke and Matrix--What Approach to Immature Sandstone Classification?

ABSTRACT Huckenholz (1963) showed that the original arkose and graywacke overlap completely in both texture and composition; perhaps suppression of one or both terms in indicated. Graywacke has the longer, if not more significant (albeit confused), history. For 100 years in Germany and 50 in Britain, before development by Sorby of thin section petrography, graywacke was used as a purely hand specimen term based chiefly upon texture. It seems pointless to change this emphasis for an important, large, texturally-similar yet compositionally-varied rock clan. Modal analysis and interpretation of immature sandstones presents many problems, especially that of matrix which is increasingly attacked as a classificatory parameter, chiefly of maturity. But it matters not how or when conspicuous matrix of graywackes formed for it to be useful for descriptive coarse separation of pure (arenite) and impure (wacke) sandstones; genesis of fine material must be interpreted in any sand, recent or ancient. Finer subdivision can be made on a compositional basis following flexible schemes such as Gilbert's. Sedimentary structures, tectonics, provenance, depositional process and environment should be avoided in petrographic classification. If textural and compositional maturity be accepted as the prime guides in classification, then purely quantita ive placing of a rock within each maturity spectrum could replace all troublesome varietal names.

Bone Marrow Distribution as a Factor in Estimating Radiation to the Blood-Forming Organs.

Information on bone marrow distribution is collected and collated. The variation in active marrow distribution with age is considered, together with assumptions that this extension introduces. Distributions that have been adopted to estimate radiation doses to the marrow are compared. A table is provided showing distribution of active marrow in major bone groups at various ages, based on data from 100 cadavers. The data cannot be applied with mathematical accuracy to a given case. Inactive marrow may quickly be transformed to active marrow in patients who have infections or conditions which impose a stress on the hematopoietic system. By applying cellularity data as a cellularity factor for each age, the distribution of active marrow at the age was gained. Total values at different ages give a measure, or baseline, for the active marrow that is required for maintaining a normal physiological function, but do not represent weights of marrow. For each given bone group, at each age, the percentage of total active marrow was calculated. The resultant distribution of percentage total active marrow is shown graphically. This percentage distribution of active marrow is the quantity required in studies of radiation effects on the blood- forming organs. Doses incident on themore » marrow of part of the body may then be weighted for the proportion of active marrow that is within the radiation field. Approximations within the basic data that were used to construct this distribution are discussed. It was assumed that the adult distribution of marrow spaces may also be used as the distribution of marrow spaces in children. Additional tables are provided showing marrow distribution in major body areas, since in many medical procedures parts of bones intercept a radiation field; e.g., in a given radiotherapeutic technique, fields may cover the pelvis and lumbar ventebrae only. Without details of the relative amounts of marrow within the several parts, cruder estimates of the proportion of marrow irradiated have to be made. So that a finer subdivision should be available, details for several of the bone groups have been listed in tables for ribs and vertebrae, and for the head, pelvis, and limbs. Active marrow content at a given age can be estimated by using appropriate cellularity factors as earlier described for the principal bone groups. The estimates presented here are compared with those of several previous surveys. (BBB)« less

A new phage-typing scheme for Salmonella typhi-murium.

1. A new phage-typing scheme forSalm. typhi-muriumis described which initially defines thirty-four types of the organism.2. Types recognizable with the older scheme of Felix and Callow remain distinct with the new system. However, the latter method offers a finer subdivision of the organism than does the former.3. Thirteen of the twenty-nine typing phages used in the new scheme were prepared by adaptation ofSalm. paratyphiB typing phage 3b, and nineteen are serologically indistinguishable from this phage.4. The lysogenic properties of the new types are discussed. Twenty-three out of the thirty-three type strains yielded both thermolabile and thermostable phages and a further three yielded thermolabile phages only. No phages could be isolated from the remainder.5. The distinctive host ranges of the phages carried by most types can be used for type identification.I am indebted to Miss Alison M. Dykes for her valuable assistance with this work; to Mr F. J. Flynn for help in the preparation of phage stocks; and to Dr E. S. Anderson for many helpful discussions and advice in the preparation of this paper.