Flattened Form Research Articles

Recovery of a curved surface using a finite-element method. (2nd report. Modification by means of a flattened shape).

The purpose of this paper is to propose a new scheme using the finite-element method for modification of a three-dimensional shape. When designing a curved surface, we need to have the following processes. First, various regions on a curved surface are transformed into flattened forms. Second, a curved surface is recovered from the flattened forms. Third, a new surface has to be made on the basis of the modified flattened shapes. We have already proposed methods for developing any curved surfaces and for recovering curved shapes with the use of the finite-element method. We now introduce a new idea for modification of 3D-curved surfaces using reformed flattened shape lines and additional information. To illustrate the usefulness of the method, We apply it to a shoe model as a typical and practical application.

The development of an arbitary curved surface using finite element method.

This paper describes a computer orientated method to transform any arbitary region of a curved surface from 3-D to a flattened form. The strategy is based upon a modification of the plane stress problem of the finite element method. Several applications are presented. One is a pattern shell which has traditionally been used by footwear pattern engineers and another is a flattened form for the corresponding airplane model.

Trebouxia (Pleurastrales, Chlorophyta) as a Phycobiont in the Lichen Genus Diploschistes

Summary Five species of the coccal alga Trebouxia were isolated from nine species of the lichen genus Diploschistes. Morphological characters of the vegetative cell (chloroplast structure, cell shape) and differences in the formation of autospores of the cultured strains are described and used to distinguish the phycobionts. By comparing them with the type strains, these were identified as Trebouxia crenulata, T. gigantea, T. irregularis, and T. showmanii. T. asymmetrica nov. spec, not corresponding to the type strains, is described here as a new species. The cultured phycobionts formed characteristic tetrads and cell complexes of adhering autospores. These were lacking only in T. crenulata and T. irregularis. Also within the lichen thallus, T. showmanii differed from T. irregularis by forming adhering autospores. In T. irregularis, the chloroplast was often modified to a flattened form (parietal stage) before initiation of protoplast division began. T. showmanii was the most frequent phycobiont of the investigated Diploschistes species. In Diploschistes ocellatus and D. scruposus, more than one Trebouxia species was found to serve as a suitable algal partner.

Morphological and Functional Characterization of the Larval Hemocytes of the Cabbage White Butterfly, Pieris rapae crucivora

Structural and functional characteristics of larval hemocytes of the cabbage white butterfly, Pieris rapae crucivora, are described. Larval hemolymph contains three types of hemocytes : prohemocytes, plasmatocytes, and granular cells with typical morphology. Prohemocytes were smooth surface, while both plasmatocytes and granular cells were characterized by cytoplasmic processes. Plasmatocytes with a combination of lamellipodia and filopodia were capable of random locomotive activity in vitro after attachment in a flattened form. Of these hemocytes, only the granular cells possessing many filopodia were able to phagocytose sheep erythrocytes artificially injected into the larval hemocoel as a foreign material. These observations of hemocytes will aid the understanding of the cellular defense reactions against foreign materials in this species.

Remnants of a submerged pre-Jurassic (Devonian?) landscape on Orphan Knoll, offshore eastern Canada

A large group of discrete peaks occurs on the northeastern surface of Orphan Knoll at water depths between 1800 and 2800 m. Long-range side-scan sonographs are used in conjunction with seismic reflection profiles to establish their flattened conical form. They commonly rise to 300 m above the sea floor and occupy basal areas up to 2 km in diameter at that level. Inclusion of the buried lower parts of these mounds may double estimates of both the height and diameter. The sonographs indicate that the mounds have a random distribution within an elongate northwesterly trending belt. Previous suggestions of their possible origin, such as remnants of dykes or ridges of resistant sedimentary strata, are rejected and an alternative explanation of a zone of partially buried Devonian reef knolls is proposed.

Cycloheptatriene/norcaradiene. Valence isomerization and conformational effects

The conformational behavior of cycloheptatriene and its valence isomer, norcaradiene, depends dramatically on the exocyclic angle at C7. According to MINDO/3 calculations, the boat conformation exists in a flattened form, thus decreasing this angle. As a consequence the equilibrium is shifted towards the cycloheptatriene valence isomer. The calculations are used to explain previous experimental data.

Paleoecology of Oligocene Reef Tract, Southwestern Puerto Rico: ABSTRACT

A well-exposed, late Oligocene, barrier-reef sequence, approximately 60 m thick, outcrops for at least 25 km between Guayanilla and Guanica near the southwestern coast of Puerto Rico. A virtually complete range of reef tract environments, from lagoon to deep fore-reef and basin slope, is present. Porites-Caulastrea patch reefs occur in lagoonal miliolid wackestone and packstone, while reef-flat coral shingle is represented by rudaceous grainstones. The reef-crest and reef-front zones are constructed of more than 30 species of hermatypic scleractinian corals. The reef core consists of coral boundstone framework with massive heads in point-to-point contact. The upper fore-reef facies is wackestone with a distinctive assemblage of reef corals, many of which exhibit flattened growth form. Deep fore-reef deposits are packstones of the prolific large foram Lepidocyclina (E.) undosa, while deep-basin facies are composed of pelagic mudstones, clays, and chalks which are interbedded with coral-bearing turbidites. The sequence of reef development displays a classic example of community succession from pioneer through intermediate and climax seral stages, with the coral Porites occupying a dominant to predominant role. End_of_Article - Last_Page 976------------

Morphological and compositional changes of rat plasma triglyceride-rich lipoproteins incubated with adipose tissue

Triglyceride-rich rat lipoproteins (mainly VLDL), purified by ultracentrifugation and dialysis, were incubated for 120 min in the presence of epididymal fat-pad pieces from fed rats in media containing heparin. During this process, the lipoproteins were depleted of triglycerides and proportionally enriched with proteins, causing their increased density. After incubation, electron microscopic study of the triglyceride-rich lipoproteins revealed partially degraded structures, and some particles had atypical discoid flattened form and marked lamellar structure. These findings are in agreement with those of Blanchette-Mackie & Scow (1976) in triglyceride hydrolysed chylomicrons and confirm their observation of monolayers formed by accumulated lipolytic products that move by lateral diffusion, giving rise to a spiral fold between the core triglycerides and the aqueous space.

Further Electron Microscope Studies on Pyruvate Carboxylase

Using negative staining and electron microscopic tilting techniques in conjunction with modelling experiments, the fine structure of chicken, sheep and rat pyruvate carboxylases has been studied. The overall configuration appears to be a tetrahedron-like structure consisting of two pairs of subunits in two different planes orthogonal to each other with the opposing pairs of subunits interacting with each other on their convex surfaces. The predominant form of the enzyme particles mounted and stained in the presence of acetyl-coenzyme A consisted of a compact, triangular outline enclosing three readily visible intensity maxima. When samples were mounted in the absence of acetyl-coenzyme A the molecules were more 'open' predominantly rhomboid structures. From tilting experiments it is concluded that the rhomboid images found in the absence of acetyl-coenzyme A represent partly or wholly flattened forms of the tetrahedron-like molecule. A feature of the enzyme when mounted in the absence of acetyl-coenzyme A was the existence of a 'cleft' along the longitudinal midline of each subunit, suggesting that the subunits may consist of two distinct domains.

Adhesion and spreading of Limulus blood cells on artificial surfaces.

The horseshoe crab Limulus has a single cell type in the blood, the granular amoebocyte. These cells, which are non-adhesive and non-motile in the blood, transform to an adhesive and motile state following extravasation. In the present study, the events of transformation were studied by time-lapse microcinematography of cells plated on to glass. Following attachment of cells to the glass, the cells protrude filopods and engage in active motility. Motile cells show 2 convertible forms; a contracted form and a reversibly flattened form. Eventually the motile cells undergo irreversible flattening which is accompanied by spontaneous degranulation. The shapes of irreversibly spread cells are influenced by the arrangement of cell-substrate contacts established prior to degranulation, and by the pattern of contact of domains of granule-derived membrane introduced into the cell surface during granule exocytosis and their subsequent endoctyosis by the cell. The clottable protein released by spontaneous degranulation of the amoebocytes undergoes gelation in the absence of bacterial endotoxin. The ability to undergo spontaneous gelation stands in marked contrast to the absolute requirement for endotoxin for gelation of the clottable protein present in 'Limulus amoebocyte lysate', a commercially valuable preparation obtained from amoebocytes used to detect endotoxin.

Notes on the Natural History of Stylites gemmifera

Several unexpected observations were made recently while collecting plants of Stylites E. Amstutz for anatomical study. The plants were collected near the end of the growing season (18-19 April 1979) so as to obtain young plants which had just completed various numbers of growing seasons. In the type locality, Stylites is described as forming pure colonies which stand just above the water level in the lacustrine bog in which they are found (Rauh & Falk, 1959); but the plants we collected at 4100 m altitude (Karrfalt & Hunter 22, NY) near Lago Junin, 14 km north of Junin, Peru, were invariably growing in association with various flowering plants (Figs. 1 and 2) and were frequently submerged. The colonies at the Junin locality were generally in the form of radially symmetrical, dome-shaped hummocks (Fig. 1), but various other rounded shapes occurred as well. The hummocks ranged in diameter from 20 to about 200 cm. The larger hummocks generally were found to contain a larger proportion of other plants in addition to Stylites than did the smaller ones. The plants in the hummocks were extremely densely packed and usually stood above the water level, but some hummocks were partially or completely submerged. The submerged portions of these hummocks were populated nearly exclusively by Stylites, but the emergent portions included other plants as well (Fig. 5). These plants usually were rather small (with stems a few millimeters in length), but some were quite good-sized (stems 2-4 cm long) and bore about 40 leaves up to 7 cm long, as well as numerous gemmae. Their leaves did not have the typical flattened form with deflexed tips, but rather were subtriangular to terete in cross section and ascending. All intermediate forms between these atypical leaves and those described by Rauh and Falk (1959) were also seen; the variation in leaf morphology will be described in detail in a subsequent report. The plants with the atypical leaf form always were submerged and not densely crowded. On the other hand, plants bearing typical leaves occurred both above and below the water level in the bog, but these plants always were densely crowded. Leaf form correlates with population density rather than with emergence or submergence. The nature of this correlation is not certain, but experiments in progress suggest that it is largely or entirely environmental. In contrast to its very limited geographical range, Stylites is extremely vigorous and abundant where appropriate conditions for its growth exist. The Junin locality is a bog which has been used as a pasture for many years. It is heavily grazed by sheep and llamas, as indicated by the cropped herbage (Figs. 1 and 4) and abundant llama dung. The Stylites plants, however, very rarely show any evidence of even accidental damage by the animals. The Junin locality occupies at least several acres; we were unable to determine its full extent due to our anoxemia and consequent lack of energy. The leaves of Stylites are coated with considerable quantities of mucilage, as are the basal parts of the leaves of all Isoetes species of which we have seen living

Selective site segregation in Patelloida (Chiazamea) Pygmaea (Dunker) and P.(C.) Lampanicola Habe (gastropoda: Patellacea) on a Hong Kong shore

Although originally described as a separate species, Patelloida (Chiazacmea) lampanicola Habe has subsequently been regarded as a “form” of P. (C.) pygmaea (Dunker). The conical shape of the shell in the former was assumed to result from the settlement and growth of some individuals of the population upon shells of intertidal Batillaria (Potamididae). This paper reports upon an analysis of a population of limpets resident on a small sand flat in Hong Kong and it is concluded that Patelloida (C.) lampanicola is distinct from P. (C.) pygmaea. This conclusion is based upon differences in radula teeth structure, shell morphometrics and behaviour. Furthermore it has been demonstrated that the earlier confusion surrounding these species results from a very nice example of selective site segregation. P. (C.) pygmaea inhabits stones and empty shells (in this region of its total range) embedded in the sand but can occasionally does reside, up to a length of 4.2 mm, upon Batillaria shells. Thereafter the flattened form of the limpet shell, on a round substratum, presumably makes such individuals more susceptible to either predation or dislodgement. The high-coned Patelloida (C.) lampanicola, on the other hand, almost exclusively colonizes living Batillaria (particularly B. zonalis and B. multiformis) shells but can, with little or no significant alteration in form, also colonize stones. Patelloida (C.) lampanicola has a positive behavioural response towards Batillaria and is clearly living in symbiotic association with the potamid. The benefits accrued by both are discussed. Thus, the limited hard substratum of a primarily soft shore environment has been segregated by these two limpets; one occupies the stones and oyster shells, the other the dense cover of epifaunal potamid snails.

Establishment of epidermal cell columns in mammalian skin: Computer simulation

The present investigation shows an example of tissue formation in relation to individual cell properties. Epidermis of mammalian skin has recently been shown to be organized during ontogeny into neat vertical cell columns, in which a cell approximates the flattened form of Kelvin's tetrakaidecahedron, a 14-sided body with eight hexagonal faces and six square faces. Such an epidermal architecture is compatible with the organization and turnover of stacked cells, a constant loss of surface cells and a supply that cells from a basal layer differentiate during migration to the surface. The developmental process from irregular cell aggregate into neat columns in skin is simulated on a digital electronic computer with the assumption as follows: a new cell migrating upward from a basal layer jostles and settles at the less crowded area among upper cells. After migration of many cells to the surface, the simulation demonstrates that cells have been stacked in neat columns, and the stability of the architecture is also shown.

Determination of cell form in cultured fibroblasts: Role of surface components and cytokinetic elements

Functions involved in the determination of the morphology of mouse embryo fibroblasts have been studied using as a system the cell rounding and reflattening related to the presence or absence of a protein component of the cell surface [18]. Cells that had undergone rounding following the removal of the surface protein gradually reflattened if their protein synthesis was not impaired but could rapidly revert to the flattened state if a fraction containing the surface protein was returned to the cells. Studies with sodium azide and potassium cyanide showed that both the rounding and reflattening were energy-dependent. When the rounded state was induced the organised appearance of the microfilaments present in the cortical layer adjacent to the plasma membrane was lost. However, microfilament structures reappeared when rounded cells respread over the glass substrate. On the other hand no reflattening occurred if microfilament function was impaired by treatment with cytochalasin B (CB), showing a requirement of microfilament integrity for the flattened form to be manifest. Microtubules also were shown to be involved in shape determination as their integrity was necessary for cells to progress from the flattened form to the rounded state, but they did not appear to be primarily involved in the process of reflattening. The distribution of macromolecular components of the plasma membrane was also shown to affect changes of cell shape as cross-linking of surface receptors by concanavalin A (ConA) or specific anti-cell immunoglobulins prevented cells from acquiring the rounded form and treatment of cells with media of low pH, which causes aggregation of intra-membrane particles, also prevented rounding. A comparison between quiescent cells and cells in S phase showed the changes of morphology to be similar in nature, but more prompt and marked in the S population. The indication of the studies presented is that determination of cell form requires the cooperative interaction between the protein component of the cell surface, integral constituents of the plasma membrane and cytokinetic organelles.

Scanning Electron Microscope Studies of the Spines and Glochids of the Opuntioideae (Cactaceae)

The genera of the Opuntioideae are surveyed for certain spine and glochid structures. Retrorse scabrosity of both spines and glochids is regarded as characteristic of the subfamily. Critical differences are noted in the bases of the glochids, flattened fish-tail forms being found in Opuntia, Nopalea, Cylindropuntia, Tephrocactus, and Tacinga, and enlarged, rounded, hollow forms in Pterocactus and Grusonia. Small unflattened bases are found in Pereskiopsis and Quiahentia. Minor variations of the flattened form of glochid base are noted in Cylindropuntia, Austrocylindropuntia, and Opuntia brasiliensis; and the possible significance of the structures is discussed.

SCANNING ELECTRON MICROSCOPE STUDIES OF THE SPINES AND GLOCHIDS OF THE OPUNTIOIDEAE (CACTACEAE)

The genera of the Opuntioideae are surveyed for certain spine and glochid structures. Retrorse scabrosity of both spines and glochids is regarded as characteristic of the subfamily. Critical differences are noted in the bases of the glochids, flattened fish‐tail forms being found in Opuntia, Nopalea, Cylindropuntia, Tephrocactus, and Tacinga, and enlarged, rounded, hollow forms in Pterocactus and Grusonia. Small unflattened bases are found in Pereskiopsis and Quiahentia. Minor variations of the flattened form of glochid base are noted in Cylindropuntia, Austrocylindropuntia, and Opuntia brasiliensis; and the possible significance of the structures is discussed.

Lanthanide‐induced shifts in proton NMR spectra of cyclohexanones

AbstractThe lanthanide‐induced shifts (LIS) of the lanthanide shift reagent (LSR) Eu(FOD)3 are reported for a large number of cyclohexanones, especially those which are highly substituted. The following compounds were synthesized and characterized: 3‐(aryl)‐3,5,5‐trimethylcyclohexanones, in which aryl = 1‐naphthyl, phenyl, o‐anisyl, m‐anisyl, p‐anisyl and p‐chlorophenyl. Some analogous compounds were also studied: 3,5,5‐trimethylcyclohexanone, 4‐tert‐butyl‐cyclohexanone, 3,3,5,5‐tetramethylcyclohexanone 3‐(1‐naphthyl)5,5‐dimethylcyclohexanone and para‐tert‐butyl‐anisole. A method for the regression analysis of the concentration dependence of the LIS of these substrates is developed and reported, and used to derive the limiting incremental LIS (Δ2) for the LS2 complex and to evaluate the proton chemical shifts (δ0) in the absence of LSR. An ‘incremental dilution’ technique was found to be most appropriate to insure constant substrate concentrations, needed to extract both Δ2 and δ0. The conformations of the 3‐(aryl)‐type systems and analogous compounds were studied via LIS and found to conform to:—(i) an axially disposed aryl substituent in the 3,3,5,5‐tetra‐substituted cyclohexanones and (ii) a flattened chair form of the cyclohexanone ring with distortions in this chair form being an increase in the syn‐diaxial (C‐3, C‐5) substituent distance (C‐3 and C‐5 substituents still eclipsed). The LIS were fully compatible with these structural assumptions.

Form and Internal Structure of Recent Algal Nodules (Rhodolites) from Bermuda

The growth forms and internal structure of living coralline algal nodules (here termed rhodolites) from a shallow Bermuda bay contain a surprisingly sensitive record of the frequency of their movement by wave action. The growing rhodolites of Whalebone Bay are pebble to cobble-sized spheroids found at depths of 1-2 m. In section, a nucleus (either algal or foreign) is surrounded by a laminated shell or coralline algae with two different growth forms: laminar and columnar. In almost all the larger rhodolites the nucleus is invariably succeeded first by laminar and then columnar structure. Growing spheroidal and ellipsoidal rhodolites with smooth surfaces (laminar structure) are concentrated in sandy channels; those flattened ones with bumpy surfaces (columnar structure) are half buried in skeletal sand or trapped in rock-floor depressions. Evidently, the spheroidal form and laminar structure indicate frequent movement, while the flattened form and columnar structure indicate immobility. The frequency of mo...

Coated vesicles and synaptogenesis. A developmental study in the cerebellar cortex of the rat

Summary The distribution of coated vesicles was examined by electron microscopy in the cerebellar cortex of rats aged 0, 3, 5, 7, 10, 12, 15, 21 and 30 days. Vesicles with external coverings were identified in closed (spherical), open (flask-like) and flattened forms. Closed coated vesicles were seen in large numbers in the vicinity of the Golgi apparatus, and sometimes in direct continuity with its cisterns, in rapidly growing regions of immature neurons, such as the apical cones of Purkinje cells in 3–7-day-old animals, and in the dendrites of Purkinje cells in the 7–10-day-old animals. Closed, open and flat coated vesicles were seen on the surface of cells, and in neurons these were frequently opposite cell processes with which synapses are formed, such as in the dendrites of Purkinje cells opposite parallel fibers. Occasionally, these open coated vesicles were situated opposite cell processes which had dense membranes, and sometimes they were continuous with the dense membranes of early attachment sites or presumptive synapses. In the mossy axon terminals in the glomeruli, open granular coated vesicles were common in the 21- and 30-day-old rats. It was postulated that the coated vesicles may be involved in the formation of early attachment sites or of the dense membranes of synapses, and the following sequence of events was suggested. Through a budding process spherical, coated dense membranes are formed from the membranes of the cisterns of the Golgi apparatus. These spherical vesicles migrate to the surface of cells and after attachment to the membrane open up and unfold over its surface. When this unfolding becomes complete the flat dense membranes contribute material to attachment sites or synaptic membranes. Coated vesicles may also contribute to the expansion of the dense membrane surfaces of already formed synapses. The relation between these coated vesicles and micropinosomes was discussed and examples were illustrated where parts of the parallel fiber actually protruded into the cavity of the Purkinje cell coated vesicles.

Crystal and molecular structure of methyl 4,6-O-benzylidene-2-O-p-bromobenzenesulphonyl-3-cyano-3-deoxy-α-D-altropyranoside

The crystal structure of methyl 4,6-O-benzylidene-2-O-p-bromobenzenesulphonyl-3-cyano-3-deoxy-α-D-altro-pyranoside (I) has been determined by three-dimensional X-ray analysis. The crystals are triclinic, space group P1, with Z= 1, a= 6·05, b= 7·39, and c= 12·62 A, and α= 105·6, β= 97·4, and γ= 92·3°. The atomic parameters were determined by Fourier and least-squares calculations. The final value of R over 1810 independent reflexions is 12·2%. The pyranose ring is in a slightly flattened chair form and the O(methyl)⋯ C(cyano) separation is 3·03 A.