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Sample records for elastica

  1. The many faces of elastica

    CERN Document Server

    Mladenov, Ivaïlo M

    2017-01-01

    This book provides an introduction to the mathematical aspects of Euler's elastic theory and its application. The approach is rigorous, as well as visually depicted, and can be easily digested. The first few chapters introduce the needed mathematical concepts from geometry and variational calculus. The formal definitions and proofs are always illustrated through complete derivations and concrete examples. In this way, the reader becomes acquainted with Cassinian ovals, Sturmian spirals, co-Lemniscates, the nodary and the undulary, Delaunay surfaces, and their generalizations. The remaining chapters discuss the modeling of membranes, mylar balloons, rotating liquid drops, Hele-Shaw cells, nerve fibers, Cole's experiments, and membrane fusion. The book is geared towards applied mathematicians, physicists and engineers interested in Elastica Theory and its applications.

  2. Balance de carbono en un bosque novedoso de Castilla elastica: resultados preliminares

    Science.gov (United States)

    Ariel E. Lugo; Jessica Fonseca da Silva; Alejandra María. Sáez Uribe

    2008-01-01

    During June 17 and 18, 2008, a Castilla elastica forest located in El Tallonal, municipality of Arecibo, functioned as a carbon sink. The net photosynthetic rate ranged from 14.28 (native species) and 21.96 (C. elastica) g C m-1 day-1 and respiration of leaves, stems, and soil varied from 13.76 (native species) and 16.88 (C. elastica) g C m-1 day-1. The net...

  3. Development of quality standards of medicinal mistletoe – Helicanthes elastica (Desr. Danser employing Pharmacopoeial procedures

    Directory of Open Access Journals (Sweden)

    K.N. Sunil Kumar

    2016-11-01

    Full Text Available Helicanthes elastica (Desr. Danser (Loranthaceae, commonly known as Indian mango mistletoe, is a parasitic shrub found widely growing on mango trees in southern India. Development of monographic quality standards is need of the hour for Pharmacopoeial/extra-Pharmacopoeial and folk medicinal plants. Systematic pharmacognostical evaluation of leaves of H. elastica has been carried out employing Pharmacopoeial procedures of testing herbal drugs. Macro–microscopic features of H. elastica leaf were recorded. Ethanolic extract was tested positive for alkaloids, steroids, carbohydrates, tannins, saponins and phenols. HPTLC fingerprint profile was developed for the identification of extracts using reference standard β-sitosterol glucoside. Results of the present investigation would serve as a source of pharmacognostical information and a document to control the quality of H. elastica (Desr. Danser. Keywords: HPTLC, Mango mistletoe, Medicinal plant monograph, Quality control

  4. Magnesium affects rubber biosynthesis and particle stability in Ficus elastica, Hevea brasiliensis and Parthenium argentatum

    Science.gov (United States)

    Natural rubber biosynthesis occurs in laticifers of Ficus elastica and Hevea brasiliensis, and in parenchyma cells of Parthenium argentatum. Natural rubber is synthesized by rubber transferase using allylic pyrophosphates as initiators, isopentenyl pyrophosphate as monomeric substrate and magnesium ...

  5. A Compliant Bistable Mechanism Design Incorporating Elastica Buckling Beam Theory and Pseudo-Rigid-Body Model

    DEFF Research Database (Denmark)

    Sönmez, Ümit; Tutum, Cem Celal

    2008-01-01

    In this work, a new compliant bistable mechanism design is introduced. The combined use of pseudo-rigid-body model (PRBM) and the Elastica buckling theory is presented for the first time to analyze the new design. This mechanism consists of the large deflecting straight beams, buckling beams...... and the buckling Elastica solution for an original compliant mechanism kinematic analysis. New compliant mechanism designs are presented to highlight where such combined kinematic analysis is required....

  6. Chaotic non-planar vibrations of the thin elastica. Part I: Experimental observation of planar instability

    Science.gov (United States)

    Cusumano, J. P.; Moon, F. C.

    1995-01-01

    In this two-part paper, the results of an investigation into the non-linear dynamics of a flexible cantilevered rod (the elastica) with a thin rectangular cross-section are presented. An experimental examination of the dynamics of the elastica over a broad parameter range forms the core of Part I. In Part II, the experimental work is related to a theoretical study of the mechanics of the elastica, and the study of a two-degree-of-freedom model obtained by modal projection. The experimental system used in this investigation is a rod with clamped-free boundary conditions, forced by sinusoidally displacing the clamped end. Planar periodic motions of the driven elastica are shown to lose stability at distinct resonant wedges, and the resulting motions are shown in general to be non-planar, chaotic, bending-torsion oscillations. Non-planar motions in all resonances exhibit energy cascading and dynamic two-well phenomena, and a family of asymmetric, bending-torsion non-linear modes is discovered. Correlation dimension calculations are used to estimate the number of active degrees of freedom in the system.

  7. Antimicrobial Potential of Helicanthus elastica (Desr. Danser - A less explored Indian mistletoe Growing on Mango Trees

    Directory of Open Access Journals (Sweden)

    Koppala Narayana Sunil Kumar

    2014-10-01

    Full Text Available Helicanthus elastica (Desr. Danser (Loranthaceae is a less-known medicinally important mistletoe species occurring in India. It is used to check abortion, and also in vesical calculi and kidney affections. There are no detailed studies reporting the antimicrobial potential of this plant. Based on the traditional use and the rich phenolic composition of the whole plant, the antimicrobial property of the alcohol extract was analyzed and the results are outlined in the present paper. For the analysis, zone of inhibition, and minimum inhibitory concentration were used, and the total activity was assayed by standard methodologies. The antimicrobial activity was studied against bacteria like Aeromonas hydrophila, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pyogenes, Vibrio fischeri, and a fungus Candida albicans. Of the eight tested bacteria, the alcoholic extract of H. elastica was found to be active against K. pneumoniae, A. hydrophila, E. coli, and V. fischeri at concentration ranging from 250 to 500 μg/ml. C. albicans showed inhibition only at a concentration of 2000 μg/ml.

  8. Potential effect of the medicinal plants Calotropis procera, Ficus elastica and Zingiber officinale against Schistosoma mansoni in mice.

    Science.gov (United States)

    Seif el-Din, Sayed H; El-Lakkany, Naglaa M; Mohamed, Mona A; Hamed, Manal M; Sterner, Olov; Botros, Sanaa S

    2014-02-01

    Calotropis procera (Ait.) R. Br. (Asclepiadaceae), Ficus elastica Roxb. (Moraceae) and Zingiber officinale Roscoe (Zingiberaceae) have been traditionally used to treat many diseases. The antischistosomal activity of these plant extracts was evaluated against Schistosoma mansoni. Male mice exposed to 80 ± 10 cercariae per mouse were divided into two batches. The first was divided into five groups: (I) infected untreated, while groups from (II-V) were treated orally (500 mg/kg for three consecutive days) by aqueous stem latex and flowers of C. procera, latex of F. elastica and ether extract of Z. officinale, respectively. The second batch was divided into four comparable groups (except Z. officinale-treated group) similarly treated as the first batch in addition to the antacid ranitidine (30 mg/kg) 1 h before extract administration. Safety, worm recovery, tissues egg load and oogram pattern were assessed. Calotropis procera latex and flower extracts are toxic (50-70% mortality) even in a small dose (250 mg/kg) before washing off their toxic rubber. Zingiber officinale extract insignificantly decrease (7.26%) S. mansoni worms. When toxic rubber was washed off and ranitidine was used, C. procera (stem latex and flowers) and F. elastica extracts revealed significant S. mansoni worm reductions by 45.31, 53.7 and 16.71%, respectively. Moreover, C. procera extracts produced significant reductions in tissue egg load (∼34-38.5%) and positively affected oogram pattern. The present study may be useful to supplement information with regard to C. procera and F. elastica antischistosomal activity and provide a basis for further experimental trials.

  9. Densidad de artrópodos activos en la superficie del suelo de un bosque novedoso de Castilla elastica

    Science.gov (United States)

    Maria Rivera; Ariel E. Lugo; Shalom V. Vázquez

    2008-01-01

    During the month of June 2008 we collected arthropods active on the surface of the ground in a forest of Castilla elastica located in the northern karst’s Tallonal Reserve in Arecibo, Puerto Rico. In each of 4 plots of 10 m x 10 m we placed three randomly distributed pitfall traps. The traps, which allowed the passage of organisms smaller than 5 mm wide, remained on...

  10. Biological activities of plant extracts from Ficus elastica and Selaginella vogelli: An antimalarial, antitrypanosomal and cytotoxity evaluation

    Directory of Open Access Journals (Sweden)

    Jean Emmanuel Mbosso Teinkela

    2018-01-01

    Full Text Available The cytotoxic, antiplasmodial, and antitrypanosomal activities of two medicinal plants traditionally used in Cameroon were evaluated. Wood of Ficus elastica Roxb. ex Hornem. aerial roots (Moraceae and Selaginella vogelii Spring (Selaginellaceae leaves were collected from two different sites in Cameroon. In vitro cell-growth inhibition activities were assessed on methanol extract of plant materials against Plasmodium falciparum strain 3D7 and Trypanosoma brucei brucei, as well as against HeLa human cervical carcinoma cells. Criteria for activity were an IC50 value < 10 μg/mL. The extract of S. vogelii did not significantly reduce the viability of P. falciparum at a concentration of 25 μg/mL but dramatically affected the trypanosome growth with an IC50 of 2.4 μg/mL. In contrast, at the same concentration, the extract of F. elastica exhibited plasmodiacidal activity (IC50 value of 9.5 μg/mL and trypanocidal (IC50 value of 0.9 μg/mL activity. Both extracts presented low cytotoxic effects on HeLa cancer cell line. These results indicate that the selected medicinal plants could be further investigated for identifying compounds that may be responsible for the observed activities and that may represent new leads in parasitical drug discovery.

  11. Total Phenol Content and In Vitro Antioxidant Potential of Helicanthus elastica (Desr. Danser-A Less-explored Indian Mango Mistletoe

    Directory of Open Access Journals (Sweden)

    Koppala Narayana Sunil Kumar

    2014-10-01

    Full Text Available Natural products are an important source of antioxidant molecules like tannins, phenolic compounds, flavonoids, etc., Helicanthus elastica (Desr. Danser (Loranthaceae is one such plant belonging to the category of mistletoe, and grows commonly on the mango trees in India. In the present study, an attempt has been made to assess the antioxidant properties of the plant. Ethanol extract of H. elastica growing on mango tree was studied using different in vitro models. Shade-dried whole plant material was extracted with ethanol by cold percolation. Fifty milligrams of the alcohol extract of H. elastica was weighed and dissolved in 10 ml of methanol. The resultant 5 mg/ml solution was suitably diluted to obtain different concentrations. Total phenol content, reducing power assay, and scavenging of free radicals like nitric oxide, hydroxyl, hydrogen peroxide, and 1,1-diphenyl-2-picrylhydrazyl were studied by standardized in vitro chemical methods using ascorbic acid as the standard. The total phenol content of the plant was found to be 1.89% w/w. The extract showed good reducing power as well as scavenging of free radicals (nitric oxide, hydroxyl, superoxide anion, and hydrogen peroxide at concentrations ranging from 5 to 100 μg/ml. The study revealed the antioxidant potential of H. elastica.

  12. Estructura y química del suelo en un bosque de Castilla elastica en el carso del norte de Puerto Rico: resultados de una calicata

    Science.gov (United States)

    Christian A. Viera Martinez; Oscar Abelleira; Ariel E. Lugo

    2008-01-01

    We dug a soil pit of 1m x 1m x 1m in a forest dominated by Castilla elastica, a tree for shade coffee introduced in the karst of northern Puerto Rico. We found four soil horizons (designation notes in parenthesis) (A) organic soil matter (E) mineral soil leachate (B) aerobic mineral soil, and (C) saturated soil. The total storage of soil organic matter was 143 Mg/ha....

  13. Centrifugal fingering in a curved Hele-Shaw cell: A generalized Euler's elastica shape for the two-fluid interface

    Science.gov (United States)

    Miranda, Jose; Brandao, Rodolfo

    2017-11-01

    We study a family of generalized elastica-like equilibrium shapes that arise at the interface separating two fluids in a curved rotating Hele-Shaw cell. This family of stationary interface solutions consists of shapes that balance the competing capillary and centrifugal forces in such a curved flow environment. We investigate how the emerging interfacial patterns are impacted by changes in the geometric properties of the curved Hele-Shaw cell. A vortex-sheet formalism is used to calculate the two-fluid interface curvature, and a gallery of possible shapes is provided to highlight a number of peculiar morphological features. A linear perturbation theory is employed to show that the most prominent aspects of these complex stationary patterns can be fairly well reproduced by the interplay of just two interfacial modes. The connection of these dominant modes to the geometry of the curved cell, as well as to the fluid dynamic properties of the flow, is discussed. We thank CNPq (Brazilian Research Council) for financial support under Grant No. 304821/2015-2.

  14. A New Apparatus for Inelastic, Quasi-Elastic and Elastic Cold Neutron Measurements; Un nouveau appareil pour les mesures de diffusion inelastique , quasi-elastique et elastique des neutrons lents; Novyj pribor dlya izmereniya neuprugogo, kvaziuprugogo i uprugogo rasseyaniya kholodnykh nejtrohov; Nuevo aparato para mediciones inelastic as, cuasi elasticas y elasticas de neutrones frios

    Energy Technology Data Exchange (ETDEWEB)

    Otnes, K; Palevsky, H [Brookhaven National Laboratory, Upton, NY (United States)

    1963-01-15

    despersion de la longueur d'onde (largeur totale a mi-hauteur) seront respectivement de 16 {mu}s et 0,16 A pour des neutrons incidents ayant une longueur d'onde de 4 A; l'intensite de la bouffee sur l'echantillon (4 x 1,6 cm) sera de 2 x 10{sup 6} n/s pouf mesures de diffusion quasi-elastique et elastique, la configuration a trois rotors conviendra parfaitement. La duree de la bouffee et la dispersion de longueur d'onde correspondante peuvent atteindre des valeurs aussi faibles que 8 {mu}s et 0, 04 A, ce qui donne une intensite de 10{sup 4} n/s sur un echantillon de 4 x 0, 8 cm. La longueur d'onde et la resolution en temps peuvent etre ajustees entre les; deux limites susmentionnees, de maniere a obtenir l'intensite de flux maximum pour une experience determinee. (author) [Spanish] Se esta construyendo un nuevo selector mecanico destinado al reactor de flujo intenso de Brookhaven. El aparato es del tipo de tres elementos rotores en fase. Los rotores, de 80 cm de diametro, giran a una velo- cidad maxima de 15000 rev/min y se han disenado de modo que emitan tres rafagas de neutrones monocromaticos por revolucion. Dos de los rotores giran alrededor de un eje horizontal, mientras que el tercero lo hace verticalmente. El sistma puede funcionar con uno, dos or tres elementos selectores, segun el tipo de medicion que se quiera efectuar. Para las mediciones inelasticas en que los neutrones ganan energia, lo mas indicado es utilizar un sistema de dos rotores. En este sistema, la duracion de las rafagas sera de 16 {mu}s y el ensanchamiento de longitudes de onda (amplitud plena a la mitad del valor maximo) de 0,16 A para neutrones incidentes de 4 A; la intensidd en la muestra (4 x 1,6 cm) sera de 2 x 10{sup 6} n/s. para las mediciones cuasi elasticas y elasticas resultara mas apropiado el sistema de tres rotores. La duracion de las rafagas y el ensanchamiento de longitudes de onda pueden llegar a un minimo de 8 {mu}s y 0,04 A, respectivamente, lo que representa una intensidad de 10{sup

  15. Empirical correlation among the dynamic elastic constants and the waves P and S velocities in rocks; Correlaciones empiricas entre las constantes elasticas dinamicas y las velocidades de las ondas P y S de las rocas

    Energy Technology Data Exchange (ETDEWEB)

    Contreras Lopez, Enrique [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1995-12-31

    Departing from the analysis of a data base on the velocities of the compression waves (V{sub p}) and the transverse waves (V{sub s}) in a group of 97 specimens of sedimentary, igneous and metamorphic rocks, the existence of four types of empirical correlation very well entailed between the dynamic elastic constants and the velocities V{sub p} and V{sub s}. These correlation allow the estimation with a very close approximation the elastic dynamic constants without the need of having available of the complete set of data (V{sub p}, V{sub s} and total density) that is normally required for its determination. The identified correlation is mathematically expressed by means of adjustment equations that reproduce in all of the cases the experimental values with a standard error of estimation within 10%, for the universe of rocks studied and with much less error for different specific lithological groups. The application methodologies of the correlation found for different cases of practical interest, are described. [Espanol] A partir del analisis de una base de datos experimentales sobre la velocidad de las ondas compresionales (V{sub p}) y de las ondas transversales (V{sub s}) de un conjunto de 97 especimenes de rocas sedimentarias, igneas y metamorficas, se identifica la existencia de cuatro tipos de correlaciones empiricas muy bien comportadas entre las constantes elasticas dinamicas y las velocidades V{sub p} y V{sub s}. Estas correlaciones permiten estimar con muy buena aproximacion las constantes elasticas dinamicas de las rocas sin tener que disponer del conjunto completo de datos (V{sub p}, V{sub s} y densidad total) que normalmente se requieren para su determinacion. Las correlaciones identificadas se expresan matematicamente mediante ecuaciones de ajuste que reproducen en todos los casos los valores experimentales con un error estandar de estimacion dentro de 10% para el universo de las rocas estudiadas, y con mucho menor error para diferentes grupos litologicos

  16. Empirical correlation among the dynamic elastic constants and the waves P and S velocities in rocks; Correlaciones empiricas entre las constantes elasticas dinamicas y las velocidades de las ondas P y S de las rocas

    Energy Technology Data Exchange (ETDEWEB)

    Contreras Lopez, Enrique [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1996-12-31

    Departing from the analysis of a data base on the velocities of the compression waves (V{sub p}) and the transverse waves (V{sub s}) in a group of 97 specimens of sedimentary, igneous and metamorphic rocks, the existence of four types of empirical correlation very well entailed between the dynamic elastic constants and the velocities V{sub p} and V{sub s}. These correlation allow the estimation with a very close approximation the elastic dynamic constants without the need of having available of the complete set of data (V{sub p}, V{sub s} and total density) that is normally required for its determination. The identified correlation is mathematically expressed by means of adjustment equations that reproduce in all of the cases the experimental values with a standard error of estimation within 10%, for the universe of rocks studied and with much less error for different specific lithological groups. The application methodologies of the correlation found for different cases of practical interest, are described. [Espanol] A partir del analisis de una base de datos experimentales sobre la velocidad de las ondas compresionales (V{sub p}) y de las ondas transversales (V{sub s}) de un conjunto de 97 especimenes de rocas sedimentarias, igneas y metamorficas, se identifica la existencia de cuatro tipos de correlaciones empiricas muy bien comportadas entre las constantes elasticas dinamicas y las velocidades V{sub p} y V{sub s}. Estas correlaciones permiten estimar con muy buena aproximacion las constantes elasticas dinamicas de las rocas sin tener que disponer del conjunto completo de datos (V{sub p}, V{sub s} y densidad total) que normalmente se requieren para su determinacion. Las correlaciones identificadas se expresan matematicamente mediante ecuaciones de ajuste que reproducen en todos los casos los valores experimentales con un error estandar de estimacion dentro de 10% para el universo de las rocas estudiadas, y con mucho menor error para diferentes grupos litologicos

  17. Dependence of leaf surface potential response of a plant (Ficus Elastica) to light irradiation on room temperature; Shokubutsu (gomunoki) hamen den`i no hikari shosha oto no shitsuon izonsei

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, H; Kenmoku, Y; Sakakibara, T [Toyohashi University of Technology, Aichi (Japan); Nakagawa, S [Maizuru National College of Technology, Kyoto (Japan); Kawamoto, T [Shizuoka University, Shizuoka (Japan)

    1997-11-25

    In order to clarify plant body potential information, study was made on a leaf surface potential response to light irradiation. The leaf surface potential change, total transpiration and transpiration rate of Ficus Elastica were measured using light irradiation period and room temperature as parameters. The leaf surface potential change shows a positive peak after the start of light irradiation, while a negative peak after its end. Arrival time to both peaks is constant regardless of the light irradiation period, while decrease with an increase in room temperature. Although the total transpiration increases with room temperature, this tendency disappears with an increase in light irradiation period. The transpiration rate shows its peak after the start of light irradiation. Arrival time to the peak is saturated with the light irradiation period of 60min, while decreases with an increase in room temperature. These results suggest that opening of stomata becomes active with an increase in room temperature, and the peak of the leaf surface potential after the start of light irradiation relates to the opening. 3 refs., 11 figs.

  18. The magneto-elastica: from self-buckling to self-assembly

    KAUST Repository

    Vella, D.; du Pontavice, E.; Hall, C. L.; Goriely, A.

    2013-01-01

    Spherical neodymium-iron-boron magnets are permanent magnets that can be assembled into a variety of structures owing to their high magnetic strength. A one-dimensional chain of these magnets responds to mechanical loadings in a manner reminiscent of an elastic rod. We investigate the macroscopic mechanical properties of assemblies of ferromagnetic spheres by considering chains, rings and chiral cylinders of magnets. Based on energy estimates and simple experiments, we introduce an effective magnetic bending stiffness for a chain of magnets and show that, used in conjunction with classic results for elastic rods, it provides excellent estimates for the buckling and vibration dynamics of magnetic chains. We then use this estimate to understand the dynamic self-assembly of a cylinder from an initially straight chain of magnets.

  19. The magneto-elastica: from self-buckling to self-assembly

    KAUST Repository

    Vella, D.

    2013-12-04

    Spherical neodymium-iron-boron magnets are permanent magnets that can be assembled into a variety of structures owing to their high magnetic strength. A one-dimensional chain of these magnets responds to mechanical loadings in a manner reminiscent of an elastic rod. We investigate the macroscopic mechanical properties of assemblies of ferromagnetic spheres by considering chains, rings and chiral cylinders of magnets. Based on energy estimates and simple experiments, we introduce an effective magnetic bending stiffness for a chain of magnets and show that, used in conjunction with classic results for elastic rods, it provides excellent estimates for the buckling and vibration dynamics of magnetic chains. We then use this estimate to understand the dynamic self-assembly of a cylinder from an initially straight chain of magnets.

  20. New apparatus for discriminating shapes - application to the study of neutron-proton elastic scattering at 14.6 MeV; Nouveau dispositif de discrimination de formes - Application a l'etude de la diffusion elastique neutron-proton a 14,6 MeV; Novyj diskriminator po forme - primenenie k izucheniyu uprugogo rasseyaniya nejtronproton s 14,6 MeV; Nuevo dispositivo para discriminacion de formas - Aplicacion al estudio de la dispersion elastica neutron-proton a 14,6 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Crettez, J P; Cambou, F; Ambrosino, G [Laboratoire Maurice de Broglie, Paris (France)

    1962-04-15

    impulsions dues aux rayons {gamma} permet de deduire des spectres obtenus la variation de la section efficace differentielle de diffusion elastique en fonction de l'angle pour les neutrons de la reaction d-t. [Spanish] La vida media de los centelleos en el yoduro de cesio varia segun la naturaleza de la particula ionizante. La vida mas corta corresponde a la densidad de ionizacion mas elevada. Los autores aprovechan esta propiedad para distinguir entre si particulas que producen centelleos de amplitud analoga. El aparato descrito es un discriminador de forma de impulsos. Mide el tiempo que tarda el centelleo en pasar de su maximo a una fraccion regulable de dicha amplitud. Un convertidor de tiempo-amplitud produce un impulso cuya amplitud es proporcional al tiempo medido de este modo. La memoria compara las configuraciones de los centelleos producidos por las particulas alfa, los protones y los electrones, y presenta los resultados obtenidos. Tambien describe la aplicacion de este metodo a la medicion de los protones de retroceso que pone en movimiento un flujo de neutrones en un difusor hidrogenado de poco espesor. La supresion de los impulsos debidos a los rayos gamma permite calcular, a partir de los espectros obtenidos, la variacion de la seccion eficaz diferencial de dispersion elastica en funcion del angulo para los neutrones de la reaccion d-t. (author) [Russian] Srednyaya prodolzhitel'nost' zhizni stsintillyatsij v jodistom tsezii menyaetsya v zavisimosti ot kharaktera ioniziruyushchej chastitsy. Samoj vysokoj plotnosti ionizatsii sootvetstvuet samaya korotkaya prodolzhitel'nost' zhizni. EHto svojstvo ispol'zuetsya dlya obnaruzheniya razlichnykh chastits, dayushchikh stsintillyatsii analogichnoj amplitudy. Opisyvaemyj pribor yavlyaetsya diskriminatorom po forme. On izmeryaet vremya, zatrachivaemoe stsintillyatsiej dlya perekhoda ot svoego maksimuma do upravlyaemoj chasti ehtoj amplitudy. Vremya-amplitudnyj preobrazovatel' daet impul's, vysota kotorogo proportsional

  1. Discrete is it enough? The revival of Piola-Hencky keynotes to analyze three-dimensional Elastica

    Science.gov (United States)

    Turco, Emilio

    2018-04-01

    Complex problems such as those concerning the mechanics of materials can be confronted only by considering numerical simulations. Analytical methods are useful to build guidelines or reference solutions but, for general cases of technical interest, they have to be solved numerically, especially in the case of large displacements and deformations. Probably continuous models arose for producing inspiring examples and stemmed from homogenization techniques. These techniques allowed for the solution of some paradigmatic examples but, in general, always require a discretization method for solving problems dictated by the applications. Therefore, and also by taking into account that computing powers are nowadays more largely available and cheap, the question arises: why not using directly a discrete model for 3D beams? In other words, it could be interesting to formulate a discrete model without using an intermediate continuum one, as this last, at the end, has to be discretized in any case. These simple considerations immediately evoke some very basic models developed many years ago when the computing powers were practically inexistent but the problem of finding simple solutions to beam deformation problem was already an emerging one. Actually, in recent years, the keynotes of Hencky and Piola attracted a renewed attention [see, one for all, the work (Turco et al. in Zeitschrift für Angewandte Mathematik und Physik 67(4):1-28, 2016)]: generalizing their results, in the present paper, a novel directly discrete three-dimensional beam model is presented and discussed, in the framework of geometrically nonlinear analysis. Using a stepwise algorithm based essentially on Newton's method to compute the extrapolations and on the Riks' arc-length method to perform the corrections, we could obtain some numerical simulations showing the computational effectiveness of presented model: Indeed, it presents a convenient balance between accuracy and computational cost.

  2. Determination of the fast neutrons spectra by the Elastic scattering method (n, p); Determinacion del espectro de neutrones rapidos por el metodo de la dispersion elastica (n, p)

    Energy Technology Data Exchange (ETDEWEB)

    Elizalde D, J

    1973-07-01

    This work consists in determining the fast neutron spectra emitted by a Pu-Be isotopic source. The implemented technique is based in the spectrometry (n, p). This consists in making to fall on a fast neutrons beams (polyenergetic) over a thin film of hydrogenated material, detecting the spectra of emitted protons at a fix angle. The polyethylene film and the used solid state detector are inside of a vacuum chamber. The detector is placed at 30 degree with respect to direction of the incident neutrons beam. The protons spectra is stored in a multichannel. the energy is obtained with the prior calibration of the system. The data processing involves the transformation of the protons spectra observed at the falling on neutrons spectra over the film. The energy of the neutrons is related with that of the protons, according to the collision kinematical equations. The cross section of elastic collision of the neutrons with the hydrogen atoms is obtained from literature. Applying these relations to the observed spectra it is obtained the falling on neutron spectra over the film. (Author)

  3. Thermodynamic analysis of mechanical behaviour in the elastic region of blends of recycled poly (ethylene terephthalate) and recycled polyolefins; Analise termodinamica do comportamento mecanico na regiao elastica de blendas de poli (tereftalato de etileno) reciclado e poliolefinas recicladas

    Energy Technology Data Exchange (ETDEWEB)

    Marconcini, Jose M. [Universidade Federal do Parana Univ. (UFPR), Curitiba, PR (Brazil). Inst. de Tecnologia para o Desenvolvimento; Ruvolo Filho, Adhemar [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Dept. de Quimica]. E-mail: adhemar@power.ufscar.br

    2006-10-15

    This work describes the study using mechanical tests with the blend of recycled poly(ethylene terephthalate) (PET) and recycled polyolefin with and without the addition of polypropylene grafted with maleic anhydride and poly(ethylene-co-octene-1). A thermodynamic approach based on the Helmholtz work function was applied in the analysis of mechanical tests, correlating the effects of energy storage and from the compatibilizer on the elastic region of the materials. For the system studied, the polyolefin-rich region shows higher storage of elastic energy corroborating the morphology images obtained from SEM analysis. The thermodynamic analysis seems a useful tool to evaluate the compatibilizer effect in polymeric immiscible blends. In this work, more specifically, this method was used to analyze the mechanical behavior of different compositions of recycled polymeric commodity materials. (author)

  4. Antiproton-proton elastic scattering at 3.0 and 4.0 GeV/C; Difusion elastica antiproton-proton a 3,0 y 4,0 GeV/C

    Energy Technology Data Exchange (ETDEWEB)

    Unamuno, S

    1965-07-01

    This paper presents the results-obtained in studying the two-prong interactions observed in the Saclay 81 cm hydrogen bubble chamber exposed to the 3.0 and 4.0 GeV/c antiproton beams from CERN Proton-Synchroton. Total elastic cross-sections corresponding to both energies are given. The results are given. The results are compared with those of p-p scaterring at different energies and with those of p-p scattering. Several optical-models, from the simples one (the black disk model) to a rather elaborated, four-parameters model have been applied. These models can explain some of the experimental results but fail in predicting the angular distribution of large angle scattering. (Author)

  5. Traits and Resource Use of Co-Occurring Introduced and Native Trees in a Tropical Novel Forest

    Science.gov (United States)

    Jéssica Fonseca da Silva; Ernesto Medina; Ariel Lugo

    2017-01-01

    Novel forests are naturally regenerating forests that have established on degraded lands and have a species composition strongly influenced by introduced species. We studied ecophysiological traits of an introduced species (Castilla elastica Sessé) and several native species growing side by side in novel forests dominated by C. elastica ...

  6. The ‘Sticky Elastica’: delamination blisters beyond small deformations

    KAUST Repository

    Wagner, Till J. W.; Vella, Dominic

    2013-01-01

    We consider the form of an elastic loop adhered to a rigid substrate: the 'Sticky Elastica'. In contrast to previous studies of the shape of delamination 'blisters', the theory developed accounts for deflections with large slope (i.e. geometrically

  7. Simultaneous measurement of angular distribution of elastic scattering for {sup 6}Li, {sup 7}Be, and {sup 8}B in {sup 58}Ni; Medida simultanea de Distribuciones Angulares de Dispersion Elastica para {sup 6}Li, {sup 7}Be, y {sup 8}B en {sup 58}Ni

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz S, A. [Facultad de Ciencias, UAEM, Toluca, Estado de Mexico (Mexico); Martinez Q, E.; Aguilera R, E.F.; Murillo O, G.; Lizcano C, D.; Gomez C, A. [Departamento de Aceleradores, ININ, 52750 La Marquesa, Estado de Mexico (Mexico)

    2007-07-01

    The experimental angular distributions of elastic scattering for the projectiles {sup 6}Li, {sup 7}Be, {sup 8}B in {sup 58}Ni were obtained. Using the Optical model with a Woods-Saxon potential form, as much for the real part as for the imaginary one, an adjustment to the experimental data varying only the depth of the imaginary part of the potential is made. A comparison of the results obtained for each projectile is made. (Author)

  8. Traits and Resource Use of Co-Occurring Introduced and Native Trees in a Tropical Novel Forest

    Directory of Open Access Journals (Sweden)

    Jéssica Fonseca da Silva

    2017-09-01

    Full Text Available Novel forests are naturally regenerating forests that have established on degraded lands and have a species composition strongly influenced by introduced species. We studied ecophysiological traits of an introduced species (Castilla elastica Sessé and several native species growing side by side in novel forests dominated by C. elastica in Puerto Rico. We hypothesized that C. elastica has higher photosynthetic capacity and makes more efficient use of resources than co-occurring native species. Using light response curves, we found that the photosynthetic capacity of C. elastica is similar to that of native species, and that different parameters of the curves reflected mostly sun light variation across the forest strata. However, photosynthetic nitrogen use-efficiency as well as leaf area/mass ratios were higher for C. elastica, and both the amount of C and N per unit area were lower, highlighting the different ecological strategies of the introduced and native plants. Presumably, those traits support C. elastica’s dominance over native plants in the study area. We provide empirical data on the ecophysiology of co-occurring plants in a novel forest, and show evidence that different resource-investment strategies co-occur in this type of ecosystem.

  9. Elastogranular Mechanics: Buckling, Jamming, and Structure Formation

    Science.gov (United States)

    Schunter, David J.; Brandenbourger, Martin; Perriseau, Sophia; Holmes, Douglas P.

    2018-02-01

    Confinement of a slender body into a granular array induces stress localization in the geometrically nonlinear structure, and jamming, reordering, and vertical dislodging of the surrounding granular medium. By varying the initial packing density of grains and the length of a confined elastica, we identify the critical length necessary to induce jamming, and demonstrate how folds couple with the granular medium to localize along grain boundaries. Above the jamming threshold, the characteristic length of elastica deformation is shown to diverge in a manner that is coupled with the motion and rearrangement of the grains, suggesting the ordering of the granular array governs the deformation of the slender structure. However, overconfinement of the elastica will vertically dislodge grains, a form of stress relaxation in the granular medium that illustrates the intricate coupling in elastogranular interactions.

  10. Elastogranular Mechanics: Buckling, Jamming, and Structure Formation.

    Science.gov (United States)

    Schunter, David J; Brandenbourger, Martin; Perriseau, Sophia; Holmes, Douglas P

    2018-02-16

    Confinement of a slender body into a granular array induces stress localization in the geometrically nonlinear structure, and jamming, reordering, and vertical dislodging of the surrounding granular medium. By varying the initial packing density of grains and the length of a confined elastica, we identify the critical length necessary to induce jamming, and demonstrate how folds couple with the granular medium to localize along grain boundaries. Above the jamming threshold, the characteristic length of elastica deformation is shown to diverge in a manner that is coupled with the motion and rearrangement of the grains, suggesting the ordering of the granular array governs the deformation of the slender structure. However, overconfinement of the elastica will vertically dislodge grains, a form of stress relaxation in the granular medium that illustrates the intricate coupling in elastogranular interactions.

  11. Physics to Mathematics: from Lintearia to Lemniscate - I

    Indian Academy of Sciences (India)

    Physics to Mathematics: from Lintearia to Lemniscate - I. R Sridharan. The elastic curve, also called elastica, is the name given to the shape assumed by a uniform elastic rod when bent into a plane curve under a stress of a certain kind. This curve, defined by James Bernoulli in the lSth century has been an interesting object ...

  12. Strength measurement of optical fibers by bending

    Science.gov (United States)

    Srubshchik, Leonid S.

    1999-01-01

    A two-point bending technique has been used not only to measure the breaking stress of optical fiber but also to predict its static and dynamic fatigue. The present theory of this test is based on elastica theory of rod. However, within the limits of elastica theory the tensile and shear stresses cannot be determined. In this paper we study dynamic and static problems for optical fiber in the two- point bending test on the base of geometrically exact theory in which rod can suffer flexure, extension, and shear. We obtain the governing partial differential equations taking into account the fact that the lateral motion of the fiber is restrained by the presence of flat parallel plates. We develop the computational methods for solving the initial and equilibrium free-boundary nonlinear planar problems. We derive the formulas for predicting of the tensile strength from strength in the bending and calculate one example.

  13. The ‘Sticky Elastica’: delamination blisters beyond small deformations

    KAUST Repository

    Wagner, Till J. W.

    2013-01-01

    We consider the form of an elastic loop adhered to a rigid substrate: the \\'Sticky Elastica\\'. In contrast to previous studies of the shape of delamination \\'blisters\\', the theory developed accounts for deflections with large slope (i.e. geometrically nonlinear). Starting from the classical Euler Elastica we provide numerical results for the dimensions of such blisters for a variety of end-end confinements and develop asymptotic expressions that reproduce these results well, even up to the point of self-contact. Interestingly, we find that the width of such blisters does not grow monotonically with increased confinement. Our theoretical predictions are confirmed by simple desktop experiments and suggest a new method for the measurement of the elastocapillary length for deformations that cannot be considered small. We discuss the implications of our results for applications such as flexible electronics. © 2013 The Royal Society of Chemistry.

  14. Rationalization in architecture with surfaces foliated by elastic curves

    DEFF Research Database (Denmark)

    Nørbjerg, Toke Bjerge

    analytic form using elliptic functions. We use a gradient-driven optimization to approximate arbitrary planar curves by planar elastic curves. The method depends on an explicit parameterization of the space of elastic curves and on a method for finding a good initial guess for the optimization. We......We develop methods for rationalization of CAD surfaces using elastic curves, aiming at a costeffective fabrication method for architectural designs of complex shapes. By moving a heated flexible metal rod though a block of expanded polystyrene, it is possible to produce shapes with both positive...... and negative Gaussian curvature, either for direct use or for use as moulds for concrete casting. If we can control the shape of the rod, while moving, we can produce prescribed shapes. The flexible rod assumes at all times the shape of an Euler elastica (or elastic curve). The elastica are given in closed...

  15. Dinamica classica dei sistemi fisici

    CERN Document Server

    Turchetti, Giorgio

    1998-01-01

    Principi generali ; problemi unidimensionali ; campo centrale ; sistemi di punti ; punto vincolato ; sistemi di punti vincolati ; simmetrie ; rotazioni e moto relativo ; corpo rigido ; sistemi lineari ; stabilità ; teoria qualitativa ; piccole oscillazioni ; principi variazionali ; trasformazioni canoniche ; serie di Lie ; proprietà dell'azione ; sistemi integrabili ; teoria perturbativa ; sistemi quasi integrabili ; sistemi caotici ; integrazione numerica ; modelli hamiltoniani ; equazioni stocastiche ; meccanica statistica ; corda elastica ; equazione delle onde ; meccanica dei continui.

  16. Dióxido de Carbono na secreção do peptídeo relacionado com Gene de Calcitonina e Substância P em pele de ratos

    OpenAIRE

    Silva, Erica Calcagno Raymundo da [UNIFESP

    2013-01-01

    Introdução: Estudos sugerem que o CO2 promova estimulo dos efeitos fisiologicos como, vasodilatacao, formacao de colageno e fibras elasticas. A Inflamacao Neurogenica (IN) e um dos primeiros eventos da cicatrizacao em resposta a um estimulo nociceptivo na pele, onde ha liberacao de neuropeptideos (NPÆs) pro-inflamatorios secretados por terminacoes nervosas, sendo lancados na fase inflamatoria da cicatrizacao. Entretanto nao ha estudos que relacionem a injecao de CO2 com a IN. Objetivo: invest...

  17. A discrete element model for the investigation of the geometrically nonlinear behaviour of solids

    Science.gov (United States)

    Ockelmann, Felix; Dinkler, Dieter

    2018-07-01

    A three-dimensional discrete element model for elastic solids with large deformations is presented. Therefore, an discontinuum approach is made for solids. The properties of elastic material are transferred analytically into the parameters of a discrete element model. A new and improved octahedron gap-filled face-centred cubic close packing of spheres is split into unit cells, to determine the parameters of the discrete element model. The symmetrical unit cells allow a model with equal shear components in each contact plane and fully isotropic behaviour for Poisson's ratio above 0. To validate and show the broad field of applications of the new model, the pin-pin Euler elastica is presented and investigated. The thin and sensitive structure tends to undergo large deformations and rotations with a highly geometrically nonlinear behaviour. This behaviour of the elastica can be modelled and is compared to reference solutions. Afterwards, an improved more realistic simulation of the elastica is presented which softens secondary buckling phenomena. The model is capable of simulating solids with small strains but large deformations and a strongly geometrically nonlinear behaviour, taking the shear stiffness of the material into account correctly.

  18. Mechanical analyses on the digital behaviour of the Tokay gecko (Gekko gecko) based on a multi-level directional adhesion model

    OpenAIRE

    Wu, Xuan; Wang, Xiaojie; Mei, Tao; Sun, Shaoming

    2015-01-01

    This paper proposes a multi-level hierarchical model for the Tokay gecko (Gekko gecko) adhesive system and analyses the digital behaviour of the G. gecko under macro/meso-level scale. The model describes the structures of G. gecko's adhesive system from the nano-level spatulae to the sub-millimetre-level lamella. The G. gecko's seta is modelled using inextensible fibril based on Euler's elastica theorem. Considering the side contact of the spatular pads of the seta on the flat and rigid subst...

  19. Designing for hot-blade cutting

    DEFF Research Database (Denmark)

    Brander, David; Bærentzen, Jakob Andreas; Clausen, Kenn

    2016-01-01

    In this paper we present a novel method for the generation of doubly-curved, architectural design surfaces using swept Euler elastica and cubic splines. The method enables a direct design to production workflow with robotic hot-blade cutting, a novel robotic fabrication method under development......-trivial constraints of blade-cutting in a bottom-up fashion, enabling an exploration of the unique architectural potential of this fabrication approach. The method is implemented as prototype design tools in MatLAB, C++, GhPython, and Python and demonstrated through cutting of expanded polystyrene foam design...

  20. On the stability of a rod adhering to a rigid surface: Shear-induced stable adhesion and the instability of peeling

    Science.gov (United States)

    Majidi, Carmel; O'Reilly, Oliver M.; Williams, John A.

    2012-05-01

    Using variational methods, we establish conditions for the nonlinear stability of adhesive states between an elastica and a rigid halfspace. The treatment produces coupled criteria for adhesion and buckling instabilities by exploiting classical techniques from Legendre and Jacobi. Three examples that arise in a broad range of engineered systems, from microelectronics to biologically inspired fiber array adhesion, are used to illuminate the stability criteria. The first example illustrates buckling instabilities in adhered rods, while the second shows the instability of a peeling process and the third illustrates the stability of a shear-induced adhesion. The latter examples can also be used to explain how microfiber array adhesives can be activated by shearing and deactivated by peeling. The nonlinear stability criteria developed in this paper are also compared to other treatments.

  1. Slip Morphology of Elastic Strips on Frictional Rigid Substrates.

    Science.gov (United States)

    Sano, Tomohiko G; Yamaguchi, Tetsuo; Wada, Hirofumi

    2017-04-28

    The morphology of an elastic strip subject to vertical compressive stress on a frictional rigid substrate is investigated by a combination of theory and experiment. We find a rich variety of morphologies, which-when the bending elasticity dominates over the effect of gravity-are classified into three distinct types of states: pinned, partially slipped, and completely slipped, depending on the magnitude of the vertical strain and the coefficient of static friction. We develop a theory of elastica under mixed clamped-hinged boundary conditions combined with the Coulomb-Amontons friction law and find excellent quantitative agreement with simulations and controlled physical experiments. We also discuss the effect of gravity in order to bridge the difference in the qualitative behaviors of stiff strips and flexible strings or ropes. Our study thus complements recent work on elastic rope coiling and takes a significant step towards establishing a unified understanding of how a thin elastic object interacts vertically with a solid surface.

  2. Characterization of atherosclerosis by histochemical and immunohistochemical methods in African grey parrots (Psittacus erithacus) and Amazon parrots (Amazona spp.).

    Science.gov (United States)

    Fricke, Cornelia; Schmidt, Volker; Cramer, Kerstin; Krautwald-Junghanns, Maria-Elisabeth; Dorrestein, Gerry M

    2009-09-01

    The aim of the study was to characterize atherosclerotic changes in African grey parrots (Psittacus erithacus) and Amazon parrots (Amazona spp.) by histochemical and immunohistochemical methods. Samples of the aorta ascendens and trunci brachiocephalici from 62 African grey parrots and 35 Amazon parrots were stained by hematoxylin and eosin and Elastica van Gieson for grading of atherosclerosis in these birds. Four different stages were differentiated. The incidence of atherosclerosis in the examined parrots was 91.9% in African grey parrots and 91.4% in Amazon parrots. To evaluate the pathogenesis in birds, immunohistochemical methods were performed to demonstrate lymphocytes, macrophages, smooth muscle cells, and chondroitin sulfate. According to the missing lymphocytes and macrophages and the absence of invasion and proliferation of smooth muscle cells in each atherosclerotic stage, "response-to-injury hypothesis" seems inapplicable in parrots. Additionally, we found alterations of vitally important organs (heart, lungs) significantly correlated with atherosclerosis of the aorta ascendens.

  3. Histological assessment of the triangular fibrocartilage complex.

    Science.gov (United States)

    Semisch, M; Hagert, E; Garcia-Elias, M; Lluch, A; Rein, S

    2016-06-01

    The morphological structure of the seven components of triangular fibrocartilage complexes of 11 cadaver wrists of elderly people was assessed microscopically, after staining with Hematoxylin-Eosin and Elastica van Gieson. The articular disc consisted of tight interlaced fibrocartilage without blood vessels except in its ulnar part. Volar and dorsal radioulnar ligaments showed densely parallel collagen bundles. The subsheath of the extensor carpi ulnaris muscle, the ulnotriquetral and ulnolunate ligament showed mainly mixed tight and loose parallel tissue. The ulnolunate ligament contained tighter parallel collagen bundles and clearly less elastic fibres than the ulnotriquetral ligament. The ulnocarpal meniscoid had an irregular morphological composition and loose connective tissue predominated. The structure of the articular disc indicates a buffering function. The tight structure of radioulnar and ulnolunate ligaments reflects a central stabilizing role, whereas the ulnotriquetral ligament and ulnocarpal meniscoid have less stabilizing functions. © The Author(s) 2015.

  4. Mast Cells in Abdominal Aortic Aneurysms

    DEFF Research Database (Denmark)

    Shi, Guo-Ping; Lindholt, Jes Sanddal

    2013-01-01

    Mast cells (MCs) are proinflammatory cells that play important roles in allergic responses, tumor growth, obesity, diabetes, atherosclerosis, and abdominal aortic aneurysm (AAA). Although the presence and function of MCs in atherosclerotic lesions have been thoroughly studied in human specimens......, in primary cultured vascular cells, and in atherosclerosis in animals, their role in AAA was recognized only recently. Via multiple activation pathways, MCs release a spectrum of mediators � including histamine, inflammatory cytokines, chemokines, growth factors, proteoglycans, and proteases � to activate...... neighboring cells, degrade extracellular matrix proteins, process latent bioactive molecules, promote angiogenesis, recruit additional inflammatory cells, and stimulate vascular cell apoptosis. These activities associate closely with medial elastica breakdown, medial smooth-muscle cell loss and thinning...

  5. Neutron Spectrometry Work at the CNEN; La spectrometrie neutronique au CNEN; Raboty po nejtronnoj spektrometrii v nkyaeh; Trabajos de espectrometria neutronica realizados en el CNEN

    Energy Technology Data Exchange (ETDEWEB)

    Caglioti, G; Ascarelli, P [Comitato Nazionale per L' energia Nucleare Euratom, G. C. R. Ispra, Varese (Italy)

    1963-01-15

    In this communication the main features of the triple axis spectrometer recently installed at the Ispra-1 reactor are presented. Preliminary results in the quasi elastic angular distribution of 1.4A neutrons scattered in liquid bromine are shown and briefly discussed. (author) [French] Dans ce memoire, l'auteur decrit les principales caracteristiques du spectrometre triaxial installe recemment au reacteur Ispra-1. Il donne et examine brievement les resultats preliminaires des experiences sur la distribution angulaire quasi elastique de neutrons de 1.4A a diffuses dans du brome liquide. (author) [Spanish] La memoria describe las principales caracteristicas del espectrometro triaxial recientemente instalado en el reactor lspra-1. Asimismo, expone brevemente los resultados iniciales de las determinaciones de distribucion angular de neutrones de 1,4 A dispersados en forma cuasi elastica por bromo liquido. (author)

  6. Maxwell Strata and Cut Locus in the Sub-Riemannian Problem on the Engel Group

    Science.gov (United States)

    Ardentov, Andrei A.; Sachkov, Yuri L.

    2017-12-01

    We consider the nilpotent left-invariant sub-Riemannian structure on the Engel group. This structure gives a fundamental local approximation of a generic rank 2 sub-Riemannian structure on a 4-manifold near a generic point (in particular, of the kinematic models of a car with a trailer). On the other hand, this is the simplest sub-Riemannian structure of step three. We describe the global structure of the cut locus (the set of points where geodesics lose their global optimality), the Maxwell set (the set of points that admit more than one minimizer), and the intersection of the cut locus with the caustic (the set of conjugate points along all geodesics). The group of symmetries of the cut locus is described: it is generated by a one-parameter group of dilations R+ and a discrete group of reflections Z2 × Z2 × Z2. The cut locus admits a stratification with 6 three-dimensional strata, 12 two-dimensional strata, and 2 one-dimensional strata. Three-dimensional strata of the cut locus are Maxwell strata of multiplicity 2 (for each point there are 2 minimizers). Two-dimensional strata of the cut locus consist of conjugate points. Finally, one-dimensional strata are Maxwell strata of infinite multiplicity, they consist of conjugate points as well. Projections of sub-Riemannian geodesics to the 2-dimensional plane of the distribution are Euler elasticae. For each point of the cut locus, we describe the Euler elasticae corresponding to minimizers coming to this point. Finally, we describe the structure of the optimal synthesis, i. e., the set of minimizers for each terminal point in the Engel group.

  7. Clusterin expression in elastofibroma dorsi.

    Science.gov (United States)

    Aigelsreiter, Ariane; Pichler, Martin; Pixner, Thomas; Janig, Elke; Schuller, Monika; Lackner, Carolin; Scheipl, Susanne; Beham, Alfred; Regauer, Sigrid

    2013-05-01

    Elastofibroma dorsi is a benign soft tissue lesion composed of abnormal elastic fibers. Degenerated elastic fibers in skin and liver are associated with clusterin, an apoprotein that shares functional properties with small heat shock proteins. We evaluated the staining pattern and possible role of clusterin in elastofibroma dorsi. Twenty-one subcutaneous elastofibromas from the scapular region were evaluated with Elastica van Gieson and Orcein stains, immunohistochemically with antibodies to clusterin, smooth muscle actin, S-100, vimentin and CD34 and correlated with clinical data with respect to physical trauma. Clusterin correlated with the staining pattern of Elastica van Gieson and labelled abnormal broad coarse fibrillar and globular elastic fibers in all elastofibromas. Orcein stains additionally identified fine oxytalan fibers which were not stained by clusterin. Clusterin staining was observed only on the outside of the elastin fibers, while the cores of fibers and globules were unstained. 4/21 elastofibromas showed cellular nodules with a myxoid/collagenous stroma. The round to oval cells showed cytoplasmic staining with vimentin and clusterin; CD34 labelled mostly cell membranes. The cells lacked SMA and S-100 expression. The central areas of the nodules were devoid of elastic fibers, but the periphery contained coarse fibers and globules. 9/ 11 patients, for whom clinical data were available, reported trauma to the scapular region. Many investigated ED were associated with trauma, which supports a reactive/degenerative etiology of ED. The abnormal large elastic fibers in all ED were enveloped by clusterin. Clusterin deposition may protect elastic fibers from degradation and thus contribute indirectly to the tumor-like presentation of ED.

  8. INVASIVE WEEDS IN BOGOR BOTANIC GARDENS, INDONESIA AND ITS IMPLICATION ON SURROUNDING LANDSCAPES

    Directory of Open Access Journals (Sweden)

    Edi Santosa

    2014-07-01

    Full Text Available Conservation areas with the objective for collection and exchange plant materials have been speculated as weed bank for surrounding areas. Objective of this study was to identify and characterize ruderal invasive weeds in the Bogor Botanic Gardens (BBG. Observations were conducted in all vak (collection blocks in the BBG in order to identify the weeds species, determine their invasiveness, dominance and distribution. Weeds associations with host plants were observed. Current weed control program and data of dead trees collection were analyzed in relevant to weed. Distribution of weeds outside BBG was observed by transects method following river and road directions. Results showed that there were seven invasive weeds, i.e., Cecropia adenopus (Cecropiaceae, Cissus nodosa Blume (Vitaceae, Cissus sicyoides Blume (Vitaceae, Dioscorea bulbifera L. (Dioscoreaceae, Ficus elastica Roxb. (Moraceae, Mikania micrantha H.B.K. (Asteraceae and Paraserianthes falcataria (L. Nielsen (Fabaceae. These seven weeds species invaded 41 out of 215 plant families in BBG. Six species of weeds, i.e., C. adenopus, C. nodosa Blume., C. sicyoides Blume., D. bulbifera L., M. micrantha H.B.K. and P. falcataria (L. Nielsen, were introduced as BBG collections for the first time while the F. elastica Roxb was considered as native. It is most likely that the weeds dispersal agents are the wind, birds, bats, visitors, and waters. All of these weeds existed in surrounding areas outside BBG. Given the detrimental impact of invasive weeds on the plant collection in BBG, it is necessary to develop long–term comprehensive control measures both inside and neighboring areas by involving other government authorities beyond BBG.

  9. Elastoplasticidad anisotropa de metales en grandes deformaciones

    Science.gov (United States)

    Caminero Torija, Miguel Angel

    El objetivo de este trabajo es el desarrollo de modelos y algoritmos numericos que simulen el comportamiento del material bajo estas condiciones en el contexto de programas de elementos finitos, dando como resultado predicciones mas precisas de los procesos de conformado y deformacion plastica en general. Para lograr este objetivo se han desarrollado diversas tareas destinadas a mejorar las predicciones en tres aspectos fundamentales. El primer aspecto consiste en la mejora de la descripcion del endurecimiento cinematico anisotropo en pequenas deformaciones, lo cual se ha realizado a traves de modelos y algoritmos implicitos de superficies multiples. Ha sido estudiada la consistencia de este tipo de modelos tanto si estan basados en una regla implicita similar a la de Mroz o en la regla de Prager. Ademas se han simulado los ensayos de Lamba y Sidebottom, obteniendo, en contra de la creencia general, muy buenas predicciones con la regla de Prager. Dichos modelos podrian ser extendidos de forma relativamente facil para considerar grandes deformaciones a traves de procedimientos en deformaciones logaritmicas, similares a los desarrollados en esta tesis y detallados a continuacion. El segundo aspecto consiste en la descripcion de la anisotropia elastoplastica inicial. Esto se ha conseguido mediante el desarrollo de modelos y algoritmos para plasticidad anisotropa en grandes deformaciones, bien ignorando la posible anisotropia elastica, bien considerandola simultaneamente con la anisotropia plastica. Para ello ha sido necesario desarrollar primero un nuevo algoritmo de elastoplasticidad anisotropa en pequenas deformaciones consistentemente linealizado y sin despreciar ningun termino, de tal forma que se conserve la convergencia cuadratica de los metodos de Newton. Este algoritmo en pequenas deformaciones ha servido para realizar la correccion plastica de dos algoritmos en grandes deformaciones. El primero de estos algoritmos es una variacion del clasico algoritmo de

  10. Effect of plant and fungous metabolites on Meloidogyne exigua Efeito de metabólitos vegetais e fúngicos sobre Meloidogyne exigua

    Directory of Open Access Journals (Sweden)

    Daniel Rufino Amaral

    2009-01-01

    Full Text Available As nematodes cause great damage to Brazilian coffee production, effective methods to control these parasites are necessary. In a previous work Allium cepa L., Cajanus cajan (L. Mill., Crotalaria juncea L., Ficus elastica Roxb., Ruta graveolens L., Stylosanthes guianensis Aubl., Leucaena leucocephala (Lam. Dewit., Brachiaria decumbens Stapf., Catharanthus roseus G. Don, Tagetes minuta L., Ricinus communis L. and Coffea arabica L. produced active substances against Meloidogyne exigua Goeldi, a nematode widely disseminated through Brazilian coffee fields. Thus, aqueous extracts of such plants, collected in a different season from that of the previous work, as well as crude metabolites produced in liquid medium by Fusarium moniliforme Shelden and Cylindrocarpon magnusianum (Sacc. Woll., were submitted to in vitro assays with M. exigua second-stage juveniles (J2. All plants and fungi produced active substances against J2. Therefore, their metabolites were applied to six-month-old coffee plants inoculated with M. exigua. After 90 days in a greenhouse, those samples obtained from A. cepa, L. leucocephala, R. graveolens and F. moniliforme inhibited the production of galls and eggs by M. exigua, demonstrating potential to control such parasite.Os nematóides acarretam grandes perdas aos produtores brasileiros de café, sendo necessário o desenvolvimento de métodos eficientes para o seu controle. Em trabalho anterior, Allium cepa L., Cajanus cajan (L. Mill., Crotalaria juncea L., Ficus elastica Roxb., Ruta graveolens L., Stylosanthes guianensis Aubl., Leucaena leucocephala (Lam. Dewit., Brachiaria decumbens Stapf., Catharanthus roseus G. Don, Tagetes minuta L., Ricinus communis L. e Coffea arabica L. produziram substâncias ativas contra o nematóide Meloidogyne exigua Goeldi, que é amplamente disseminado pelos cafezais brasileiros. Dando continuidade a esse trabalho, extratos aquosos das plantas mencionadas, coletadas em época diferente daquela

  11. Advances and applications of rock physics for hydrocarbon exploration; Avances y aplicaciones en fisica de rocas para exploracion de hidrocarburos

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Meleza, L.; Valle-Molina, C. [Instituto Mexicano del Petroleo (Mexico)]. E-mails: lvargasm@imp.mx; cvallem@imp.mx

    2012-10-15

    Integration of the geological and geophysical information with different scale and features is the key point to establish relationships between petrophysical and elastic characteristics of the rocks in the reservoir. It is very important to present the fundamentals and current methodologies of the rock physics analyses applied to hydrocarbons exploration among engineers and Mexican students. This work represents an effort to capacitate personnel of oil exploration through the revision of the subjects of rock physics. The main aim is to show updated improvements and applications of rock physics into seismology for exploration. Most of the methodologies presented in this document are related to the study the physical and geological mechanisms that impact on the elastic properties of the rock reservoirs based on rock specimens characterization and geophysical borehole information. Predictions of the rock properties (lithology, porosity, fluid in the voids) can be performed using 3D seismic data that shall be properly calibrated with experimental measurements in rock cores and seismic well log data. [Spanish] Se discuten los fundamentos de fisica de rocas y las implicaciones analiticas para interpretacion sismica de yacimientos. Se considera conveniente difundir, entre los ingenieros y estudiantes mexicanos, los fundamentos y metodologias actuales sobre el analisis de la fisica de rocas en exploracion de hidrocarburos. Este trabajo representa un esfuerzo de capacitacion profesional en exploracion petrolera en el que se difunde la relevancia de la fisica de rocas. El interes principal es exponer los avances tecnologicos y aplicaciones actuales sobre fisica de rocas en el campo de sismologia de exploracion. La mayoria de las metodologias estudia los mecanismos fisicos y geologicos que controlan las propiedades elasticas de los yacimientos de hidrocarburos, a partir de nucleos de roca y registros geofisicos de pozo. Este conocimiento se usa para predecir propiedades de la

  12. Three-dimensional analysis of alveolar wall destruction in the early stage of pulmonary emphysema.

    Science.gov (United States)

    Kobayashi, Yukihiro; Uehara, Takeshi; Kawasaki, Kenji; Sugano, Mitsutoshi; Matsumoto, Takehisa; Matsumoto, Gou; Honda, Takayuki

    2015-03-01

    The morphological mechanism of alveolar wall destruction during pulmonary emphysema has not been clarified. The aim of this study was to elucidate this process three-dimensionally. Lung specimens from five patients with pulmonary emphysema were used, and five controls with normal alveolar structure were also examined. Sections 150 μm thick were stained with hematoxylin and eosin, elastica, and silver impregnation, and immunostained with selected antibodies. We examined these sections three-dimensionally using a laser confocal microscope and a light microscope. There were only a few Kohn's pores and no fenestrae in the normal alveoli from the controls. In the lungs of the emphysema patients a small rupture appeared in the extremely thin alveolar wall among the alveolar capillaries. This rupture enlarged to form a circle surrounded by the capillaries, which was called an alveolar fenestra. Two neighboring fenestrae fused by breakdown of the collapsed or cord-like capillary between them to form a large fenestra. The large fenestrae fused repeatedly to become larger, and these were bordered by thick elastic fibers constructing an alveolar framework. Alveolar wall destruction during emphysema could start from small ruptures of the alveolar wall that become fenestrae surrounded by capillaries, which fuse repeatedly to become larger fenestrae rimmed with elastic fibers. The alveolar capillary network could initially prevent enlargement of the fenestrae, and the thick elastic fibers constituting the alveolar framework could secondarily prevent destruction of the alveolar wall structure. © 2014 Wiley Periodicals, Inc.

  13. Combined Euler column vibration isolation and energy harvesting

    Science.gov (United States)

    Davis, R. B.; McDowell, M. D.

    2017-05-01

    A new device that combines vibration isolation and energy harvesting is modeled, simulated, and tested. The vibration isolating portion of the device uses post-buckled beams as its spring elements. Piezoelectric film is applied to the beams to harvest energy from their dynamic flexure. The entire device operates passively on applied base excitation and requires no external power or control system. The structural system is modeled using the elastica, and the structural response is applied as forcing on the electric circuit equation to predict the output voltage and the corresponding harvested power. The vibration isolation and energy harvesting performance is simulated across a large parameter space and the modeling approach is validated with experimental results. Experimental transmissibilities of 2% and harvested power levels of 0.36 μW are simultaneously demonstrated. Both theoretical and experimental data suggest that there is not necessarily a trade-off between vibration isolation and harvested power. That is, within the practical operational range of the device, improved vibration isolation will be accompanied by an increase in the harvested power as the forcing frequency is increased.

  14. Mechanical analyses on the digital behaviour of the Tokay gecko (Gekko gecko) based on a multi-level directional adhesion model.

    Science.gov (United States)

    Wu, Xuan; Wang, Xiaojie; Mei, Tao; Sun, Shaoming

    2015-07-08

    This paper proposes a multi-level hierarchical model for the Tokay gecko ( Gekko gecko ) adhesive system and analyses the digital behaviour of the G. gecko under macro/meso-level scale. The model describes the structures of G. gecko 's adhesive system from the nano-level spatulae to the sub-millimetre-level lamella. The G. gecko 's seta is modelled using inextensible fibril based on Euler's elastica theorem. Considering the side contact of the spatular pads of the seta on the flat and rigid substrate, the directional adhesion behaviour of the seta has been investigated. The lamella-induced attachment and detachment have been modelled to simulate the active digital hyperextension (DH) and the digital gripping (DG) phenomena. The results suggest that a tiny angular displacement within 0.25° of the lamellar proximal end is necessary in which a fast transition from attachment to detachment or vice versa is induced. The active DH helps release the torque to induce setal non-sliding detachment, while the DG helps apply torque to make the setal adhesion stable. The lamella plays a key role in saving energy during detachment to adapt to its habitat and provides another adhesive function which differs from the friction-dependent setal adhesion system controlled by the dynamic of G. gecko 's body.

  15. Distribution of elastic fibers in the head and neck: a histological study using late-stage human fetuses

    Science.gov (United States)

    Kinoshita, Hideaki; Umezawa, Takashi; Omine, Yuya; Kasahara, Masaaki; Rodríguez-Vázquez, José Francisco; Murakami, Gen

    2013-01-01

    There is little or no information about the distribution of elastic fibers in the human fetal head. We examined this issue in 15 late-stage fetuses (crown-rump length, 220-320 mm) using aldehyde-fuchsin and elastica-Masson staining, and we used the arterial wall elastic laminae and external ear cartilages as positive staining controls. The posterior pharyngeal wall, as well as the ligaments connecting the laryngeal cartilages, contained abundant elastic fibers. In contrast with the sphenomandibular ligament and the temporomandibular joint disk, in which elastic fibers were partly present, the discomalleolar ligament and the fascial structures around the pterygoid muscles did not have any elastic fibers. In addition, the posterior marginal fascia of the prestyloid space did contain such fibers. Notably, in the middle ear, elastic fibers accumulated along the tendons of the tensor tympani and stapedius muscles and in the joint capsules of the ear ossicle articulations. Elastic fibers were not seen in any other muscle tendons or vertebral facet capsules in the head and neck. Despite being composed of smooth muscle, the orbitalis muscle did not contain any elastic fibers. The elastic fibers in the sphenomandibular ligament seemed to correspond to an intermediate step of development between Meckel's cartilage and the final ligament. Overall, there seemed to be a mini-version of elastic fiber distribution compared to that in adults and a different specific developmental pattern of connective tissues. The latter morphology might be a result of an adaptation to hypoxic conditions during development. PMID:23560235

  16. P-odd effects in πN-scattering at low energies and determination of the isotopical structure of the weak nonleptonic interaction

    International Nuclear Information System (INIS)

    Gershtein, S.S.; Folomeshkin, V.N.; Khlopov, M.Yu.

    1974-01-01

    P-odd effects in the πN-scattering on a target polarized along and again a pion beam have been considered. The P-odd correlations are intensified by interference of weak and strong interactions, whose amplitude is great in the energy range of the order of 100 to 300 MeV. When measuring cross-section differences of the πN-scattering at meson factories, it is possible to hope that the Lobashow integral method may be used in this range. The P-odd amplitudes have been calculated in the approximation of low-energy pions from the P-odd πNN vertex. High-energy meson effects are taken account of in the model of a rho-meson exchange. A kinematic analysis shows that the P-odd effects in a backward charge exchange reaction are sensitive to the presence of neutral currents. Investigation of the P-odd effects in a forward (elastica and with charge exchange) πN-scattering makes it possible to establish the isotopic structure of the nonlepton weak interaction and in particular to check the assumption of an intensified rho-meson exchange which has been offered by. Danilov to explain the high value of circular polarization of γ-quanta in the np → dγ reaction

  17. Evaluation of roadside greenbelt trees damage caused by strangler plants in Bogor

    Science.gov (United States)

    Danniswari, Dibyanti; Nasrullah, Nizar

    2017-10-01

    Certain plants are called stranglers (hemiepiphyte) because they grow on host trees and slowly choking the host, which often results in the host’s death. The existence of strangler plants on roadside greenbelt trees is quite common in Bogor, but they may cause tree’s failure and threaten users’ safety. To prevent such hazard, evaluation of roadside greenbelt trees damage caused by strangler plants is important. This study was directed to analyse the vegetation of strangler plants in Bogor, to assess the damage caused by stranglers, and to compose strangled trees maintenance recommendations. This study was conducted in March to May 2014 by doing survey at five major roads in Bogor, which were Jalan Ahmad Yani, Jalan Sudirman, Jalan Pemuda, Jalan Semeru, and Jalan Juanda. The results showed that strangler species found in Bogor are Ficus benjamina, Ficus glauca, Ficus elastica, and Schefflera actinophylla. The most common species in Bogor is F. benjamina. Host trees that tend to be preferred by strangler plants are trees with large trunk, many branches, and medium to high height. The maintenance for every strangled tree is different according to the damage level, mild to severe damage could be treated by strangler root cutting to tree logging, respectively.

  18. Patterns through elastic instabilities, from thin sheets to twisted ribbons

    Science.gov (United States)

    Damman, Pascal

    Sheets embedded in a given shape by external forces store the exerted work in elastic deformations. For pure tensile forces, the work is stored as stretching energy. When the forces are compressive, several ways to store the exerted work, combining stretching and bending deformations can be explored. For large deflections, the ratio of bending, Eh3ζ2 /L4 and stretching, Ehζ4 /L4 energies, suggests that strain-free solutions should be favored for thin sheets, provided ζ2 >>h2 (where E , ζ , Land h are the elastic modulus, the deflection, a characteristic sheet size and its thickness). For uniaxially constrained sheets deriving from the Elastica, strain-free solutions are obvious, i.e., buckles, folds or wrinkles grow to absorb the stress of compression. In contrast, crumpled sheets exhibit ``origami-like'' solutions usually described as an assembly of flat polygonal facets delimitated by ridges focusing strains are observed. This type of solutions is particularly interesting since a faceted morphology is isometric to the undeformed sheet, except at those narrow ridges. In some cases however, the geometric constraints imposed by the external forces do not allow solutions with negligible strain in the deformed state. For instance, considering a circular sheet on a small drop, so thin that bending becomes negligible, i.e., Eh3 / γL2 geometry and a competition between various energy terms, involving stretching and bending modes.

  19. Elastin Fiber Accumulation in Liver Correlates with the Development of Hepatocellular Carcinoma.

    Science.gov (United States)

    Yasui, Yutaka; Abe, Tokiya; Kurosaki, Masayuki; Higuchi, Mayu; Komiyama, Yasuyuki; Yoshida, Tsubasa; Hayashi, Tsuguru; Kuwabara, Konomi; Takaura, Kenta; Nakakuki, Natsuko; Takada, Hitomi; Tamaki, Nobuharu; Suzuki, Shoko; Nakanishi, Hiroyuki; Tsuchiya, Kaoru; Itakura, Jun; Takahashi, Yuka; Hashiguchi, Akinori; Sakamoto, Michiie; Izumi, Namiki

    2016-01-01

    The fibrosis stage, which is evaluated by the distribution pattern of collagen fibers, is a major predictor for the development of hepatocellular carcinoma (HCC) for patients with hepatitis C. Meanwhile, the role of elastin fibers has not yet been elucidated. The present study was conducted to determine the significance of quantifying both collagen and elastin fibers. We enrolled 189 consecutive patients with hepatitis C and advanced fibrosis. Using Elastica van Gieson-stained whole-slide images of pretreatment liver biopsies, collagen and elastin fibers were evaluated pixel by pixel (0.46 μm/pixel) using an automated computational method. Consequently, fiber amount and cumulative incidences of HCC within 3 years were analyzed. There was a significant correlation between collagen and elastin fibers, whereas variation in elastin fiber was greater than in collagen fiber. Both collagen fiber (p = 0.008) and elastin fiber (p elastin fiber (p = 0.002) in addition to higher collagen fiber (p = 0.05) showed significantly higher incidences of HCC. With regard to elastin fiber, this difference remained significant in F3 patients. Furthermore, for patients with a higher collagen fiber amount, higher elastin was a significant predictor for HCC development (p = 0.02). Computational analysis is a novel technique for quantification of fibers with the added value of conventional staging. Elastin fiber is a predictor for the development of HCC independently of collagen fiber and F stage.

  20. Effect of Soil Use and Coverage on the Spectral Response of an Oxisol in the VIS-NIR-MIR Region

    Directory of Open Access Journals (Sweden)

    Javier M. Martín-López

    2017-02-01

    Full Text Available In this study, the spectral responses obtained from a Typic Red Hapludox (oxisol were analyzed under different uses and occupations: Ficus elastica cultivation, Citrus + Arachis association cultivation, transitional crops, forest, Mangifera indica, Anacardium occidentale, Elaeis guineensis (18 years, Brachiaria decumbens, Brachiaria brizantha, and Musa × paradisiaca + Zea mays at the La Libertad Research Center in the department of Meta in Colombia (4°04′ North latitude, 73°30′ West longitude, 330 MAMSL. Sampling was performed with four random replicates of the horizon A and B to determine the contents of organic carbon (CO, pH, exchangeable acidity (Ac. I, cation exchange capacity (Cc, P, Ca, Mg, K, Na, sand, lime, and clay and spectral responses were obtained in the visible band (VIS, near infrared (NIR, and infrared (MIR for each sample under laboratory conditions. A comparison was made between the obtained spectra, determining the main changes in soil properties due to their use and coverage. Variation of soil characteristics such as color, organic carbon content, presence of ferrous compounds, sand, silt, and clay content and mineralogy allow the identification of the main spectral changes of soils, demonstrating the importance of the use of reflectance spectroscopy as a tool of comparison and estimation between physical-chemical properties of the soils.

  1. Reconfiguration of a flexible fiber immersed in a 2D dense granular flow close to the jamming transition

    Science.gov (United States)

    Kolb, Evelyne; Algarra, Nicolas; Vandembroucq, Damien; Lazarus, Arnaud

    2015-11-01

    We propose a new fluid/structure interaction in the unusual case of a dense granular medium flowing against an elastic fibre acting as a flexible intruder. We experimentally studied the deflection of a mylar flexible beam clamped at one side, the other free side facing a 2D granular flow in a horizontal cell moving at a constant velocity. We investigated the reconfiguration of the fibre as a function of the fibre's rigidity and of the granular packing fraction close but below the jamming in 2D. Imposing the fibre geometry like its length or thickness sets the critical buckling force the fibre is able to resist if it was not supported by lateral grains, while increasing the granular packing fraction might laterally consolidate the fibre and prevent it from buckling. But on the other side, the approach to jamming transition by increasing the granular packing fraction will be characterized by a dramatically increasing size of the cluster of connected grains forming a solid block acting against the fibre, which might promote the fibre's deflection. Thus, we investigated the granular flow fields, the fibre's deflexion as well as the forces experienced by the fibre and compared them with theoretical predictions from elastica for different loadings along the fibre. PMMH, CNRS UMR 7636, UPMC, ESPCI-ParisTech, 10 rue Vauquelin, 75231 Paris Cedex 05, France.

  2. Micro-mechanical model for the tension-stabilized enzymatic degradation of collagen tissues

    Science.gov (United States)

    Nguyen, Thao; Ruberti, Jeffery

    We present a study of how the collagen fiber structure influences the enzymatic degradation of collagen tissues. Experiments of collagen fibrils and tissues show that mechanical tension can slow and halt enzymatic degradation. Tissue-level experiments also show that degradation rate is minimum at a stretch level coincident with the onset of strain-stiffening in the stress response. To understand these phenomena, we developed a micro-mechanical model of a fibrous collagen tissue undergoing enzymatic degradation. Collagen fibers are described as sinusoidal elastica beams, and the tissue is described as a distribution of fibers. We assumed that the degradation reaction is inhibited by the axial strain energy of the crimped collagen fibers. The degradation rate law was calibrated to experiments on isolated single fibrils from bovine sclera. The fiber crimp and properties were fit to uniaxial tension tests of tissue strips. The fibril-level kinetic and tissue-level structural parameters were used to predict tissue-level degradation-induced creep rate under a constant applied force. We showed that we could accurately predict the degradation-induce creep rate of the pericardium and cornea once we accounted for differences in the fiber crimp structure and properties.

  3. Lymphovascular invasion in more than one-quarter of small rectal neuroendocrine tumors

    Science.gov (United States)

    Kwon, Mi Jung; Kang, Ho Suk; Soh, Jae Seung; Lim, Hyun; Kim, Jong Hyeok; Park, Choong Kee; Park, Hye-Rim; Nam, Eun Sook

    2016-01-01

    AIM To identify the frequency, clinicopathological risk factors, and prognostic significance of lymphovascular invasion (LVI) in endoscopically resected small rectal neuroendocrine tumors (NETs). METHODS Between June 2005 and December 2015, 104 cases of endoscopically resected small (≤ 1 cm) rectal NET specimens at Hallym University Sacred Heart Hospital in Korea were retrospectively evaluated. We compared the detected rate of LVI in small rectal NET specimens by two methods: hematoxylin and eosin (H&E) and ancillary immunohistochemical staining (D2-40 and Elastica van Gieson); in addition, LVI detection rate difference between endoscopic procedures were also evaluated. Patient characteristics, prognosis and endoscopic resection results were reviewed by medical charts. RESULTS We observed LVI rates of 25.0% and 27.9% through H&E and ancillary immunohistochemical staining. The concordance rate between H&E and ancillary studies was 81.7% for detection of LVI, which showed statistically strong agreement between two methods (κ = 0.531, P 5 mm, P = 0.007), tumor grade 2 (P = 0.006). Among those factors, tumor grade 2 was the only independent predictive factor for the presence of LVI (HR = 4.195, 95%CI: 1.321-12.692, P = 0.015). No recurrence was observed over 28.8 mo regardless of the presence of LVI. CONCLUSION LVI may be present in a high percentage of small rectal NETs, which may not be associated with short-term prognosis. PMID:27895428

  4. Experimental investigations of the large deflection capabilities of a compliant parallel mechanism actuated by shape memory alloy wires

    International Nuclear Information System (INIS)

    Sreekumar, M; Nagarajan, T; Singaperumal, M

    2008-01-01

    This experimental study investigates the coupled effect of the force developed by the shape memory alloy (SMA) actuators and the force required for the large deflection of an elastica member in a compliant parallel mechanism. The compliant mechanism developed in house consists of a moving platform mounted on a superelastic pillar and three SMA wire actuators to manipulate the platform. A three-axis MEMS accelerometer has been mounted on the moving platform to measure its tilt angle. Three miniature force sensors have been designed and fabricated out of cantilever beams, each mounted with a pair of strain gauges, to measure the force developed by the respective actuators. The force sensors are highly sensitive and cost effective compared to commercially available miniature force sensors. Calibration of the force sensors has been accomplished with known weights, and for the three-axis MEMS accelerometer a rotary base has been considered which is usually used in optical applications. The calibration curves obtained, with R-squared values between 0.9997 and 1.0, show that both the tilt and force sensors considered are most appropriate for the respective applications. The mechanism fixed with the sensors and the drivers for the SMA actuators is integrated with a National Instrument's data acquisition system. The experimental results have been compared with the analytical results and it was found that the relative error is less than 2%. This is a preliminary study in the development of a mechanism for eye prosthesis and similar applications

  5. Modeling nonlinear problems in the mechanics of strings and rods the role of the balance laws

    CERN Document Server

    O'Reilly, Oliver M

    2017-01-01

    This book presents theories of deformable elastic strings and rods and their application to broad classes of problems. Readers will gain insights into the formulation and analysis of models for mechanical and biological systems. Emphasis is placed on how the balance laws interplay with constitutive relations to form a set of governing equations. For certain classes of problems, it is shown how a balance of material momentum can play a key role in forming the equations of motion. The first half of the book is devoted to the purely mechanical theory of a string and its applications. The second half of the book is devoted to rod theories, including Euler’s theory of the elastica, Kirchhoff ’s theory of an elastic rod, and a range of Cosserat rod theories. A variety of classic and recent applications of these rod theories are examined. Two supplemental chapters, the first on continuum mechanics of three-dimensional continua and the second on methods from variational calculus, are included to provide relevant ...

  6. Can low-dose irradiation of donor hearts before transplantation inhibit graft vasculopathy?

    International Nuclear Information System (INIS)

    Shirasawa, Bungo; Hamano, Kimikazu; Ito, Hiroshi; Gohra, Hidenori; Katho, Tomoe; Fujimura, Yoshihiko; Esato, Kensuke

    1999-01-01

    This experimental study was conducted to histopathologically determine whether the low-dose irradiation of donor hearts before transplantation can inhibit graft vasculopathy. Immediately after donor F 344 rat hearts were removed, they were treated with a single dose of radiation using 7.5 Gy, 15 Gy, or no radiation (control group). The F 344 hearts were transplanted into Lewis rats heterotopically, and cyclosporine A was injected intramuscularly for 20 days after transplantation in all groups. The hearts were harvested 90 days after transplantation, and examined for intimal thickening using elastica van Gieson staining. Severe intimal thickening was observed in both the irradiated groups, the percent intimal area of the coronary arteries was significantly increased in both these groups, to 34.3±12.9 in the 7.5 Gy group and 37.0±8.9 in the 15 Gy group, compared with 23.1±9.8 in the control group (p<0.01). In conclusion, these findings show that low-dose irradiation to donor hearts before transplantation does not inhibit graft vasculopathy. (author)

  7. A Combined First and Second Order Variational Approach for Image Reconstruction

    KAUST Repository

    Papafitsoros, K.

    2013-05-10

    In this paper we study a variational problem in the space of functions of bounded Hessian. Our model constitutes a straightforward higher-order extension of the well known ROF functional (total variation minimisation) to which we add a non-smooth second order regulariser. It combines convex functions of the total variation and the total variation of the first derivatives. In what follows, we prove existence and uniqueness of minimisers of the combined model and present the numerical solution of the corresponding discretised problem by employing the split Bregman method. The paper is furnished with applications of our model to image denoising, deblurring as well as image inpainting. The obtained numerical results are compared with results obtained from total generalised variation (TGV), infimal convolution and Euler\\'s elastica, three other state of the art higher-order models. The numerical discussion confirms that the proposed higher-order model competes with models of its kind in avoiding the creation of undesirable artifacts and blocky-like structures in the reconstructed images-a known disadvantage of the ROF model-while being simple and efficiently numerically solvable. ©Springer Science+Business Media New York 2013.

  8. The Jump Set under Geometric Regularization. Part 1: Basic Technique and First-Order Denoising

    KAUST Repository

    Valkonen, Tuomo

    2015-01-01

    © 2015 Society for Industrial and Applied Mathematics. Let u ∈ BV(Ω) solve the total variation (TV) denoising problem with L2-squared fidelity and data f. Caselles, Chambolle, and Novaga [Multiscale Model. Simul., 6 (2008), pp. 879-894] have shown the containment Hm-1 (Ju \\\\Jf) = 0 of the jump set Ju of u in that of f. Their proof unfortunately depends heavily on the co-area formula, as do many results in this area, and as such is not directly extensible to higher-order, curvature-based, and other advanced geometric regularizers, such as total generalized variation and Euler\\'s elastica. These have received increased attention in recent times due to their better practical regularization properties compared to conventional TV or wavelets. We prove analogous jump set containment properties for a general class of regularizers. We do this with novel Lipschitz transformation techniques and do not require the co-area formula. In the present Part 1 we demonstrate the general technique on first-order regularizers, while in Part 2 we will extend it to higher-order regularizers. In particular, we concentrate in this part on TV and, as a novelty, Huber-regularized TV. We also demonstrate that the technique would apply to nonconvex TV models as well as the Perona-Malik anisotropic diffusion, if these approaches were well-posed to begin with.

  9. Studies on reconstruction of the carotid artery in the neck using arterial vessels irradiated by a large amount of high voltage electron beam

    International Nuclear Information System (INIS)

    Matsumura, Hiroshi

    1978-01-01

    High voltage electron beam of 2,000,000 rad was irradiated to the common carotid arteries excised from dogs. After keeping them in a frozen state, they were replaced with the common carotid arteries of other adult dogs. The border of the artery transplanted could not be identified from the x-ray films 7 - 36 months after transplantation. There was no stenosis or dilation in the artery on either x-ray films or in histopathological examinations. There was no tissue reaction in the homologous transplantation, but all the cells died and the nuclei of muscular fibers of the tunica media disappeared. However, the internal elastica and other elastic fibers were unchanged. Cells proliferated from the original artery to form a false inner coat. Noradrenergic nerves and the vasa vasorum did not enter the graft. Thus, the arteries transplanted were only substitutive vessels. A rabbit abdominal aorta which was transplanted to a dog common carotid artery, showed sacculated dilation or obstruction. In the case of obstruction, severe tissue reaction was recognized. In the case of sacculated dilation, thinning of the arterial wall at the dilated part and fragmentation of the elastic fibers of the tunica media were observed, and other tissues also tended to be destructed and absorbed. (Ichikawa, K.)

  10. Strain tensor selection and the elastic theory of incompatible thin sheets.

    Science.gov (United States)

    Oshri, Oz; Diamant, Haim

    2017-05-01

    The existing theory of incompatible elastic sheets uses the deviation of the surface metric from a reference metric to define the strain tensor [Efrati et al., J. Mech. Phys. Solids 57, 762 (2009)JMPSA80022-509610.1016/j.jmps.2008.12.004]. For a class of simple axisymmetric problems we examine an alternative formulation, defining the strain based on deviations of distances (rather than distances squared) from their rest values. While the two formulations converge in the limit of small slopes and in the limit of an incompressible sheet, for other cases they are found not to be equivalent. The alternative formulation offers several features which are absent in the existing theory. (a) In the case of planar deformations of flat incompatible sheets, it yields linear, exactly solvable, equations of equilibrium. (b) When reduced to uniaxial (one-dimensional) deformations, it coincides with the theory of extensible elastica; in particular, for a uniaxially bent sheet it yields an unstrained cylindrical configuration. (c) It gives a simple criterion determining whether an isometric immersion of an incompatible sheet is at mechanical equilibrium with respect to normal forces. For a reference metric of constant positive Gaussian curvature, a spherical cap is found to satisfy this criterion except in an arbitrarily narrow boundary layer.

  11. Distribution of elastic fibers in the head and neck: a histological study using late-stage human fetuses.

    Science.gov (United States)

    Kinoshita, Hideaki; Umezawa, Takashi; Omine, Yuya; Kasahara, Masaaki; Rodríguez-Vázquez, José Francisco; Murakami, Gen; Abe, Shinichi

    2013-03-01

    There is little or no information about the distribution of elastic fibers in the human fetal head. We examined this issue in 15 late-stage fetuses (crown-rump length, 220-320 mm) using aldehyde-fuchsin and elastica-Masson staining, and we used the arterial wall elastic laminae and external ear cartilages as positive staining controls. The posterior pharyngeal wall, as well as the ligaments connecting the laryngeal cartilages, contained abundant elastic fibers. In contrast with the sphenomandibular ligament and the temporomandibular joint disk, in which elastic fibers were partly present, the discomalleolar ligament and the fascial structures around the pterygoid muscles did not have any elastic fibers. In addition, the posterior marginal fascia of the prestyloid space did contain such fibers. Notably, in the middle ear, elastic fibers accumulated along the tendons of the tensor tympani and stapedius muscles and in the joint capsules of the ear ossicle articulations. Elastic fibers were not seen in any other muscle tendons or vertebral facet capsules in the head and neck. Despite being composed of smooth muscle, the orbitalis muscle did not contain any elastic fibers. The elastic fibers in the sphenomandibular ligament seemed to correspond to an intermediate step of development between Meckel's cartilage and the final ligament. Overall, there seemed to be a mini-version of elastic fiber distribution compared to that in adults and a different specific developmental pattern of connective tissues. The latter morphology might be a result of an adaptation to hypoxic conditions during development.

  12. Potential hydrocarbon producing species of Western Ghats, Tamil Nadu, India

    Energy Technology Data Exchange (ETDEWEB)

    Augustus, G.D.P.S.; Jayabalan, M.; Rajarathinam, K. [Research Centre in Bombay, V.H.N.S.N. College, Virudhunagar (India); Ray, A.K. [Sardar Patel Univ., Anand (India). Dept. of Chemistry; Seiler, G.J. [USDA, ARS, Northern Crop Science Lab., Fargo, ND (United States)

    2002-09-01

    The decline in the world supplies of hydrocarbons has led to the search for alternate sources of fuel and chemicals. Plant species are potential sources of hydrocarbons. Large-scale screening of plants growing in the Western Ghats, Tamil Nadu, India was conducted to assess the hydrocarbon production and the type of isoprene compound(s) present. Three species contained more than 3% hydrocarbon. Sarcostemma brevistigma had the highest concentration of hydrocarbon with 3.6%. Seven species contained more than 2% of hydrocarbons among the plant species screened. The hydrocarbon fraction of Ficus elastica (leaf) had a gross heat value of 9834 cal/g (41.17 MJ/kg), which is close to the caloric value of fuel oil. Six hydrocarbon fractions contained gross heat values of more than 9000 cal/g (37.68 MJ/kg). Of the 13 species hydrocarbon fraction analysed, seven species contained cis-polyisoprene compounds, while two species contained trans-polyisoprenes. Cis and trans polyisoprenes are potential alternative energy sources for fuel and/or as industrial raw materials. (author)

  13. The forming of a superconductor cable during the winding of a large toroidal field coil

    International Nuclear Information System (INIS)

    Messemer, G.; Zehlein, H.

    1984-01-01

    The feasible range for the tension force which acts on a superconductor cable during the winding of a large D-shaped toroidal field coil depends strongly on the mechanical properties of the cable, on the geometry of the winding pack and on the arrangement of the equipment. The upper limit is imposed by possible damage within the cable. The lower limit is set by the need to assure enough compaction and to overcome the friction forces between the layers. Within this 'corridor' optimal control of elastic prestresses is desirable: this may be chosen with regard to the residual stresses and/or the elastic springback after removal of the coil former. This paper presents a simplified elastica conductor model built by a finite chain of intervals with constant bending moment and curvature. This paper describes the discrete model as well as the iterative shooting method, which finds the equilibrium shape of the conductor. The distributions of bending moment and shear forces around the D-shaped contour, as well as along the conductor, are given. Desirable improvements are outlined. In particular, the possibility of mitigating the stress concentration effect by supporting rollers suitably placed along the 'free' conductor near the bobbin is discussed. (author)

  14. Histological evaluation of obliterative phlebitis for the diagnosis of autoimmune pancreatitis.

    Science.gov (United States)

    Miyabe, Katsuyuki; Notohara, Kenji; Nakazawa, Takahiro; Hayashi, Kazuki; Naitoh, Itaru; Okumura, Fumihiro; Shimizu, Shuya; Yoshida, Michihiro; Yamashita, Hiroaki; Takahashi, Satoru; Ohara, Hirotaka; Joh, Takashi

    2014-04-01

    Obliterative phlebitis is a useful pathological finding for the diagnosis of lymphoplasmacytic sclerosing pancreatitis (LPSP), or type 1 autoimmune pancreatitis. The present study evaluated histological findings of obliterative phlebitis, including the significance of adding Elastica van Gieson stain (EVG) in comparison with other pancreatic conditions. Specimens of LPSP (n = 18), chronic pancreatitis (CP; n = 24), and pancreatic ductal adenocarcinoma (PDA; n = 45) were enrolled. Obliterative venous lesions (OVLs), defined as the presence of inflammatory cells and/or fibrosis inside the tunica adventitia, were counted and compared between hematoxylin and eosin stain (H&E) and EVG. OVLs were classified into three types: OVL-1, lymphoplasmacytic infiltration and fibrosis against a loose textured background; OVL-2, dense fibrosis with minimal or no lymphoplasmacytic infiltration; and OVL-3, densely packed lymphoplasmacytic infiltration without fibrosis. OVL type and OVL size were compared between disease groups. OVL counts in LPSP, CP, and PDA were significantly higher with EVG than with H&E (p < 0.001). OVL-1 was most common in LPSP (H&E 92.4 %, EVG 79.8 %), and was identified in almost all cases of LPSP, but was less common in CP and PDA. Maximum diameter and OVL count in 1 cm(2) of OVL-1 were high for LPSP. Maximum diameter of OVL-1 ≥150 μm was observed in 17 LPSP, 0 CP, and 1 PDA cases (sensitivity 94.4 %, specificity 98.6 %). Additional EVG is useful for excluding conditions mimicking OVL-1 or detecting OVL in small specimens. The presence of OVL-1 with diameter ≥150 μm is highly diagnostic for LPSP.

  15. Conformal tension in string theories and M-theory

    International Nuclear Information System (INIS)

    Barros, Manuel; Ferrandez, Angel; Lucas, Pascual

    2000-01-01

    This paper deals with string theories and M-theories on backgrounds of the form AdSxM,M being a compact principal U(1)-bundle. These configurations are the natural settings to study Hopf T-dualities (Duff et al., Nucl. Phys. B 544 (1999) 145), and so to define duality chains connecting different string theories and M-theories. There is an increasing great interest in studying those properties (physical or geometrical) which are preserved along the duality chains. For example, it is known that Hopf T-dualities preserve the black hole entropies (Duff et al., Nucl. Phys. B 544 (1999) 145). In this paper we consider a two-parameter family of actions which constitutes a natural variation of the conformal total tension action (also known as Willmore-Chen functional in differential geometry). Then, we show that the existence of wide families of solutions (in particular compact solutions) for the corresponding motion equations is preserved along those duality chains. In particular, we exhibit ample classes of Willmore-Chen submanifolds with a reasonable degree of symmetry in a wide variety of conformal string theories and conformal M-theories, that in addition are solutions of a second variational problem known as the area-volume isoperimetric problem. These are good reasons to refer those submanifolds as the best worlds one can find in a conformal universe. The method we use to obtain this invariant under Hopf T-dualities is based on the principle of symmetric criticality. However, it is used in a two-fold sense. First to break symmetry and so to reduce variables. Second to gain rigidity in direct approaches to integrate the Euler-Lagrange equations. The existence of generalized elastic curves is also important in the explicit exhibition of those configurations. The relationship between solutions and elasticae can be regarded as a holographic property

  16. Biomechanical and morphological properties of the multiparous ovine vagina and effect of subsequent pregnancy.

    Science.gov (United States)

    Rynkevic, Rita; Martins, Pedro; Hympanova, Lucie; Almeida, Henrique; Fernandes, Antonio A; Deprest, Jan

    2017-05-24

    Pelvic floor soft tissues undergo changes during the pregnancy. However, the degree and nature of this process is not completely characterized. This study investigates the effect of subsequent pregnancy on biomechanical and structural properties of ovine vagina. Vaginal wall from virgin, pregnant (in their third pregnancy) and parous (one year after third vaginal delivery) Swifter sheep (n=5 each) was harvested. Samples for biomechanics and histology, were cut in longitudinal axis (proximal and distal regions). Outcome measurements describing Young's modulus, ultimate stress and elongation were obtained from stress-strain curves. For histology samples were stained with Miller's Elastica staining. Collagen, elastin and muscle cells and myofibroblasts contents were estimated, using image processing techniques. Statistical analyses were performed in order to determine significant differences among experimental groups. Significant regional differences were identified. The proximal vagina was stiffer than distal, irrespective the reproductive status. During the pregnancy proximal vagina become more compliant than in parous (+47.45%) or virgin sheep (+64.35%). This coincided with lower collagen (-15 to -21%), higher elastin (+30 to +60%), and more smooth muscle cells (+17 to +37%). Vaginal tissue from parous ewes was weaker than of virgins, coinciding with lower collagen (-10%), higher elastin (+50%), more smooth muscle cells (+20%). It could be proposed that after pregnancy biomechanical properties of vagina do not recover to those of virgins. Since elastin has a significant influence on the compliance of soft tissues and collagen is the main "actor" regarding strength, histological analysis performed in this study justifies the mechanical behavior observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Do spotty high intensity regions found in basal ganglia on MRI T2-weighted brain images of elderly subjects indicate gliosis? Comparison of brain MRI T2-weighted images of elderly subjects and necropsy brain

    International Nuclear Information System (INIS)

    Murai, Hiroshi; Hattori, Hideyuki; Matsumoto, Masayuki

    2001-01-01

    Spotty high intensity regions are frequently found on the MRI T2-weighted brain images (T2WI) of elderly people. High intensity regions with a diameter of 3 mm or less have been considered as expanded perivascular space with no pathological implications on radiological diagnosis. However, its morphometrical basis is not clear. We examined the character of the spotty regions using brain MRI of brain screening subjects, and studied morphometrically arteriolosclerosis and perivascular tissue damage using necropsy brains of subjects aged 65 years and over. The size, number and location of the spotty high intensity regions were examined using the brain MRI of 109 T2WI which is used for brain screening at Kanazawa Medical University Hospital. The frontal lobe, temporal lobe, parietal lobe, hippocampus, midbrain and basal ganglia were sampled from 15 subjects aged 65 years and over, and the tissue sections were processed for HE stain, Elastica van Gieson stain and immunostaining with GFAP. We took photographs of brain arterioli and surrounding parenchyma with a digital telescope camera and the degree of arterioscleosis and tissue damage were assessed by measurements with an image analyzer. Spotty high intensity regions on T2WI with a diameter of 3 mm or less were observed in 95.5% subjects aged 65 years and over. 69.4% spotty region was observed in basal ganglia. There was a significant correlation between age and size. In morphometrical examination, at the basal ganglia, the density of GFAP-positive astrocytes in the perivascular tissue had a significant positive correlation with the proportional thickness of the adventitia, which is an index of arteriosclerosis, and a significant negative correlation with the size of the perivascular space. The results suggested that the spotty regions in the brain MRI of elderly people do not represent dilatations of the perivascular space, but is mild brain damage caused by arteriosclerosis. (author)

  18. Decreased Neointimal Extracellular Matrix Formation in RAGE-Knockout Mice After Microvascular Denudation

    Energy Technology Data Exchange (ETDEWEB)

    Groezinger, Gerd, E-mail: gerd.groezinger@med.uni-tuebingen.de; Schmehl, Joerg, E-mail: joerg.schmehl@med.uni-tuebingen.de; Bantleon, Ruediger, E-mail: ruediger.bantleon@med.uni-tuebingen.de; Kehlbach, Rainer, E-mail: rainer.kehlbach@uni-tuebingen.de [University of Tuebingen, Department of Diagnostic and Interventional Radiology (Germany); Mehra, Tarun, E-mail: tarun.mehra@med.uni-tuebingen.de [University of Tuebingen, Department of Dermatology (Germany); Claussen, Claus, E-mail: gerd.groezinger@med.uni-tuebingen.de; Wiesinger, Benjamin, E-mail: benjamin.wiesinger@med.uni-tuebingen.de [University of Tuebingen, Department of Diagnostic and Interventional Radiology (Germany)

    2012-12-15

    Purpose: To evaluate in vivo the role of RAGE (receptor for advanced glycated end products) in the development of restenosis and neointimal proliferation in RAGE-deficient knockout (KO) mice compared with wild-type (WT) mice in an animal model. Materials and Methods: Sixteen WT and 15 RAGE-deficient mice underwent microvascular denudation of the common femoral artery under general anaesthesia. Contralateral arteries underwent a sham operation and served as controls. Four weeks after the intervention, all animals were killed, and paraformaldehyde-fixed specimens of the femoral artery were analysed with different stains (hematoxylin and eosin and Elastica van Gieson) and several different types of immunostaining (proliferating cell nuclear antigen, {alpha}-actin, collagen, von Willebrand factor, RAGE). Luminal area, area of the neointima, and area of the media were measured in all specimens. In addition, colony-formation assays were performed, and collagen production by WT smooth muscle cells (SMCs) and RAGE-KO SMCs was determined. For statistical analysis, P < 0.05 was considered statistically significant. Results: Four weeks after denudation, WT mice showed a 49.6% loss of luminal area compared with 14.9% loss of luminal area in RAGE-deficient mice (sham = 0% loss) (P < 0.001). The neointima was 18.2 (*1000 {mu}m{sup 2} [n = 15) in the WT group compared with only 8.4 (*1000 {mu}m{sup 2} [n = 16]) in the RAGE-KO group. RAGE-KO SMCs showed significantly decreased proliferation activity and production of extracellular matrix protein. Conclusion: RAGE may be shown to play a considerable role in the formation of neointima leading to restenosis after vascular injury.

  19. Vibratory function and healing outcomes after small intestinal submucosa biomaterial implantation for chronic vocal fold scar.

    Science.gov (United States)

    Pitman, Michael J; Kurita, Takashi; Powell, Maria E; Kimball, Emily E; Mizuta, Masanobu; Chang, Siyuan; Garrett, C Gaelyn; Rousseau, Bernard

    2018-04-01

    Vocal fold scar is a major cause of dysphonia, and optimal treatments do not currently exist. Small intestinal submucosa (SIS) is a biomaterial developed for the treatment of a variety of pathologies. The purpose of this study was to investigate the effects of SIS implantation on tissue remodeling in scarred vocal folds using routine staining, immunohistochemistry, and high-speed videoendoscopy (HSV). Prospective, blinded group analysis. Thirteen New Zealand White rabbits underwent a vocal fold scarring procedure followed by microflap elevation with or without SIS implantation. Seven months later, they underwent a phonation procedure with HSV and laryngeal harvest. Alcian blue and elastica van Gieson staining and immunohistochemistry for collagen types I and III were used to evaluate histological healing outcomes. Dynamic functional remodeling of the scarred vocal fold in the presence of SIS implants was evaluated using HSV imaging to capture restoration of vibratory amplitude, amplitude ratio, and left-right phase symmetry. Density of collagen I was significantly decreased in SIS versus microflap-treated vocal folds. No differences were found between groups for hyaluronic acid, elastin, or collagen type III. Organization of elastin in the subepithelial region appeared to affect amplitude of vibration and the shape of the vocal fold edge. SIS implantation into chronic scar reduced the density of collagen I deposits. There was no evidence of a negative impact or complication from SIS implantation. Regardless of treatment type, organization of elastin in the subepithelial region may be important to vibratory outcomes. NA. Laryngoscope, 128:901-908, 2018. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

  20. Snakebites and ethnobotany in the northwest region of Colombia. Part III: neutralization of the haemorrhagic effect of Bothrops atrox venom.

    Science.gov (United States)

    Otero, R; Núñez, V; Barona, J; Fonnegra, R; Jiménez, S L; Osorio, R G; Saldarriaga, M; Díaz, A

    2000-11-01

    Thirty-one of 75 extracts of plants used by traditional healers for snakebites, had moderate or high neutralizing ability against the haemorrhagic effect of Bothrops atrox venom from Antioquia and Chocó, north-western Colombia. After preincubation of several doses of every extract (7.8-4000 microg/mouse) with six minimum haemorrhagic doses (10 microg) of venom, 12 of them demonstrated 100% neutralizing capacity when the mixture was i.d. injected into mice (18-20 g). These were the stem barks of Brownea rosademonte (Caesalpiniaceae) and Tabebuia rosea (Bignoniaceae); the whole plants of Pleopeltis percussa (Polypodiaceae), Trichomanes elegans (Hymenophyllaceae) and Senna dariensis (Caesalpiniaceae); rhizomes of Heliconia curtispatha (Heliconiaceae); leaves and branches of Bixa orellana (Bixaceae), Philodendron tripartitum (Araceae), Struthanthus orbicularis (Loranthaceae) and Gonzalagunia panamensis (Rubiaceae); the ripe fruits of Citrus limon (Rutaceae); leaves, branches and stem of Ficus nymphaeifolia (Moraceae). Extracts of another 19 species showed moderate neutralization (21-72%) at doses up to 4 mg/mouse, e.g. the whole plants of Aristolochia grandiflora (Aristolochiaceae), Columnea kalbreyeriana (Gesneriaceae), Sida acuta (Malvaceae), Selaginella articulata (Selaginellaceae) and Pseudoelephantopus spicatus (Asteraceae); rhizomes of Renealmia alpinia (Zingiberaceae); the stem of Strychnos xinguensis (Loganiaceae); leaves, branches and stems of Hyptis capitata (Lamiaceae), Ipomoea cairica (Convolvulaceae), Neurolaena lobata (Asteraceae), Ocimum micranthum (Lamiaceae), Piper pulchrum (Piperaceae), Siparuna thecaphora (Monimiaceae), Castilla elastica (Moraceae) and Allamanda cathartica (Apocynaceae); the macerated ripe fruits of Capsicum frutescens (Solanaceae); the unripe fruits of Crescentia cujete (Bignoniaceae); leaves and branches of Piper arboreum (Piperaceae) and Passiflora quadrangularis (Passifloraceae). When the extracts were independently administered

  1. Pathological diagnostic criterion of blood and lymphatic vessel invasion in colorectal cancer: a framework for developing an objective pathological diagnostic system using the Delphi method, from the Pathology Working Group of the Japanese Society for Cancer of the Colon and Rectum.

    Science.gov (United States)

    Kojima, Motohiro; Shimazaki, Hideyuki; Iwaya, Keiichi; Kage, Masayoshi; Akiba, Jun; Ohkura, Yasuo; Horiguchi, Shinichiro; Shomori, Kohei; Kushima, Ryoji; Ajioka, Yoichi; Nomura, Shogo; Ochiai, Atsushi

    2013-07-01

    The goal of this study is to create an objective pathological diagnostic system for blood and lymphatic vessel invasion (BLI). 1450 surgically resected colorectal cancer specimens from eight hospitals were reviewed. Our first step was to compare the current practice of pathology assessment among eight hospitals. Then, H&E stained slides with or without histochemical/immunohistochemical staining were assessed by eight pathologists and concordance of BLI diagnosis was checked. In addition, histological findings associated with BLI having good concordance were reviewed. Based on these results, framework for developing diagnostic criterion was developed, using the Delphi method. The new criterion was evaluated using 40 colorectal cancer specimens. Frequency of BLI diagnoses, number of blocks obtained and stained for assessment of BLI varied among eight hospitals. Concordance was low for BLI diagnosis and was not any better when histochemical/immunohistochemical staining was provided. All histological findings associated with BLI from H&E staining were poor in agreement. However, observation of elastica-stained internal elastic membrane covering more than half of the circumference surrounding the tumour cluster as well as the presence of D2-40-stained endothelial cells covering more than half of the circumference surrounding the tumour cluster showed high concordance. Based on this observation, we developed a framework for pathological diagnostic criterion, using the Delphi method. This criterion was found to be useful in improving concordance of BLI diagnosis. A framework for pathological diagnostic criterion was developed by reviewing concordance and using the Delphi method. The criterion developed may serve as the basis for creating a standardised procedure for pathological diagnosis.

  2. Ischemic Stroke: What Does the Histological Composition Tell Us About the Origin of the Thrombus?

    Science.gov (United States)

    Sporns, Peter B; Hanning, Uta; Schwindt, Wolfram; Velasco, Aglaé; Minnerup, Jens; Zoubi, Tarek; Heindel, Walter; Jeibmann, Astrid; Niederstadt, Thomas Ulrich

    2017-08-01

    The introduction of stent retrievers allows for a complete extraction and histological analysis of human thrombi. Ischemic stroke is a major health issue, and differentiation of underlying causes is highly relevant to prevent recurrent stroke. Therefore, histopathologic analysis of the embolic clots after removal may provide valuable information about underlying pathologies. This study analyzes histological clot composition and aims to identify specific patterns that might help to distinguish causes of ischemic stroke. Patients with occlusion of the carotid-T or middle cerebral artery who underwent thrombectomy at our university medical center between December 2013 and February 2016 were included. Samples were histologically analyzed (hematoxylin and eosin, Elastica van Gieson, and Prussian blue), additionally immunohistochemistry for CD3, CD20, and CD68/KiM1P was performed. These data, along with additional clinical and interventional parameters, were compared for different stroke subtypes, as defined by the TOAST (Trial of Org 10172 in Acute Stroke Treatment) classification. One hundred eighty-seven patients were included, of these, in 77 patients, cardioembolic; in 46 patients, noncardioembolic; and in 64 patients, cryptogenic pathogenesis was determined. Cardioembolic thrombi had higher proportions of fibrin/platelets ( P =0.027), less erythrocytes ( P =0.005), and more leucocytes ( P =0.026) than noncardioembolic thrombi. We observed a strong overlap of cryptogenic strokes and cardioembolic strokes concerning thrombus histology. The immunohistochemical parameters CD3, CD20, and CD68/KiM1P showed no statistically noticeable differences between stroke subtypes. Histological thrombus features vary significantly according to the underlying cause and may help to differentiate between cardioembolic and noncardioembolic stroke. In addition, our study supports the hypothesis that most cryptogenic strokes have a cardioembolic cause. © 2017 American Heart Association

  3. Fractional CO2 laser treatment for vaginal laxity: A preclinical study.

    Science.gov (United States)

    Kwon, Tae-Rin; Kim, Jong Hwan; Seok, Joon; Kim, Jae Min; Bak, Dong-Ho; Choi, Mi-Ji; Mun, Seok Kyun; Kim, Chan Woong; Ahn, Seungwon; Kim, Beom Joon

    2018-05-07

    Various studies have investigated treatment for vaginal laxity with microablative fractional carbon dioxide CO 2 laser in humans; however, this treatment has not yet been studied in an animal model. Herein, we evaluate the therapeutic effects of fractional CO 2 laser for tissue remodeling of vaginal mucosa using a porcine model, with the aim of improving vaginal laxity. The fractional CO 2 laser enables minimally invasive and non-incisional procedures. By precisely controlling the laser energy pulses, energy is sent to the vaginal canal and the introitus area to induce thermal denaturation and contraction of collagen. We examined the effects of fractional CO 2 laser on a porcine model via clinical observation and ultrasound measurement. Also, thermal lesions were histologically examined via hematoxylin-eosin staining, Masson's trichrome staining, and Elastica van Gieson staining and immunohistochemistry. The three treatment groups, which were determined according to the amount of laser-energy applied (60, 90, and 120 mJ), showed slight thermal denaturation in the vaginal mucosa, but no abnormal reactions, such as excessive hemorrhaging, vesicles, or erythema, were observed. Histologically, we also confirmed that the denatured lamina propria induced by fractional CO 2 laser was dose-dependently increased after laser treatment. The treatment groups also showed an increase in collagen and elastic fibers due to neocollagenesis and angiogenesis, and the vaginal walls became firmer and tighter because of increased capillary and vessel formation. Also, use of the fractional CO 2 laser increased HSP (heat shock protein) 70 and collagen type I synthesis. Our results show that microablative fractional CO 2 laser can produce remodeling of the vaginal connective tissue without causing damage to surrounding tissue, and the process of mucosa remodeling while under wound dressings enables collagen to increase and the vaginal wall to become thick and tightened. Lasers Surg. Med

  4. Preparation of A Spaceflight: Apoptosis Search in Sutured Wound Healing Models

    Directory of Open Access Journals (Sweden)

    Stefan Riwaldt

    2017-12-01

    Full Text Available To prepare the ESA (European Space Agency spaceflight project “Wound healing and Sutures in Unloading Conditions”, we studied mechanisms of apoptosis in wound healing models based on ex vivo skin tissue cultures, kept for 10 days alive in serum-free DMEM/F12 medium supplemented with bovine serum albumin, hydrocortisone, insulin, ascorbic acid and antibiotics at 32 °C. The overall goal is to test: (i the viability of tissue specimens; (ii the gene expression of activators and inhibitors of apoptosis and extracellular matrix components in wound and suture models; and (iii to design analytical protocols for future tissue specimens after post-spaceflight download. Hematoxylin-Eosin and Elastica-van-Gieson staining showed a normal skin histology with no signs of necrosis in controls and showed a normal wound suture. TdT-mediated dUTP-biotin nick end labeling for detecting DNA fragmentation revealed no significant apoptosis. No activation of caspase-3 protein was detectable. FASL, FADD, CASP3, CASP8, CASP10, BAX, BCL2, CYC1, APAF1, LAMA3 and SPP1 mRNAs were not altered in epidermis and dermis samples with and without a wound compared to 0 day samples (specimens investigated directly post-surgery. BIRC5, CASP9, and FN1 mRNAs were downregulated in epidermis/dermis samples with and/or without a wound compared to 0 day samples. BIRC2, BIRC3 were upregulated in 10 day wound samples compared to 0 day samples in epidermis/dermis. RELA/FAS mRNAs were elevated in 10 day wound and no wound samples compared to 0 day samples in dermis. In conclusion, we demonstrate that it is possible to maintain live skin tissue cultures for 10 days. The viability analysis showed no significant signs of cell death in wound and suture models. The gene expression analysis demonstrated the interplay of activators and inhibitors of apoptosis and extracellular matrix components, thereby describing important features in ex vivo sutured wound healing models. Collectively, the

  5. Preparation of A Spaceflight: Apoptosis Search in Sutured Wound Healing Models.

    Science.gov (United States)

    Riwaldt, Stefan; Monici, Monica; Graver Petersen, Asbjørn; Birk Jensen, Uffe; Evert, Katja; Pantalone, Desiré; Utpatel, Kirsten; Evert, Matthias; Wehland, Markus; Krüger, Marcus; Kopp, Sascha; Frandsen, Sofie; Corydon, Thomas; Sahana, Jayashree; Bauer, Johann; Lützenberg, Ronald; Infanger, Manfred; Grimm, Daniela

    2017-12-03

    To prepare the ESA (European Space Agency) spaceflight project "Wound healing and Sutures in Unloading Conditions", we studied mechanisms of apoptosis in wound healing models based on ex vivo skin tissue cultures, kept for 10 days alive in serum-free DMEM/F12 medium supplemented with bovine serum albumin, hydrocortisone, insulin, ascorbic acid and antibiotics at 32 °C. The overall goal is to test: (i) the viability of tissue specimens; (ii) the gene expression of activators and inhibitors of apoptosis and extracellular matrix components in wound and suture models; and (iii) to design analytical protocols for future tissue specimens after post-spaceflight download. Hematoxylin-Eosin and Elastica-van-Gieson staining showed a normal skin histology with no signs of necrosis in controls and showed a normal wound suture. TdT-mediated dUTP-biotin nick end labeling for detecting DNA fragmentation revealed no significant apoptosis. No activation of caspase-3 protein was detectable. FASL , FADD , CASP3 , CASP8 , CASP10 , BAX , BCL2 , CYC1 , APAF1 , LAMA3 and SPP1 mRNAs were not altered in epidermis and dermis samples with and without a wound compared to 0 day samples (specimens investigated directly post-surgery). BIRC5 , CASP9 , and FN1 mRNAs were downregulated in epidermis/dermis samples with and/or without a wound compared to 0 day samples. BIRC2 , BIRC3 were upregulated in 10 day wound samples compared to 0 day samples in epidermis/dermis. RELA/FAS mRNAs were elevated in 10 day wound and no wound samples compared to 0 day samples in dermis. In conclusion, we demonstrate that it is possible to maintain live skin tissue cultures for 10 days. The viability analysis showed no significant signs of cell death in wound and suture models. The gene expression analysis demonstrated the interplay of activators and inhibitors of apoptosis and extracellular matrix components, thereby describing important features in ex vivo sutured wound healing models. Collectively, the performed

  6. MINIMUM BRACING STIFFNESS FOR MULTI-COLUMN SYSTEMS: THEORY

    Directory of Open Access Journals (Sweden)

    J. DARÍO ARISTIZÁBAL-OCHOA

    2011-01-01

    Full Text Available Se propone un metodo que determina la rigidez minima de arrostramiento requeridos por un sistema elastico de varias columnas para lograr condiciones de pandeo sin deriva entre pisos. Las ecuaciones que evaluan la rigidez minima requerida de los arrostramientos laterales y de torsion y la carga critica de pandeo ¡§arriostrada¡¨ correspondiente para cada columna del nivel de piso se obtienen utilizando las funciones de estabilidad modificadas. Se incluyen los siguientes efectos: 1 tipos de conexiones (rigidas, semirrigidas y simples, 2 la distribucion en planta de las columnas (es decir, la orientacion de la seccion transversal y la ubicacion del centro de gravedad de cada columna, 3 deformaciones por cortante a lo largo de cada columna mediante el metodo modificado propuesto por Haringx en 1948, y 4 distribucion de la carga axial entre las columnas (es decir, el patron de carga. Los efectos de las deformaciones axial y de torsion no estan incluidos. El metodo propuesto es aplicable a estructuras 2D y 3D con conexiones rigidas, semirigidas y simple. La formulacion se presenta en este documento se basa en un trabajo previo presentado por Aristizabal-Ochoa en 2007. Se demuestra que la rigidez minima de los arrostramientos laterales y de torsion requeridos por un sistema de varias columnas depende de: 1 la distribucion en planta las columnas; 2 la variacion en altura y propiedades de la seccion transversal de las columnas; 3las rigideces a flexion y a cortante de cada columna; 4 el patron de cargas en el sistema de columnas; 5 la falta de simetria (en el patron de carga, en la disposicion de las columnas, tamanos de las columnas, y sus alturas que hacen que el pandeo combinado de torsion y flexion lateral pueden reducir la capacidad de pandeo critico de la estructura en su conjunto; y 6 las condiciones de apoyo y restricciones en el extremo superior de las columnas. El metodo propuesto se limita a sistemas multi-columna con columnas elasticas y

  7. Adrenomedullin and angiopoietin-1 additively restore erectile function in diabetic rats: comparison with the combination therapy of vascular endothelial growth factor and angiopoietin-1.

    Science.gov (United States)

    Nishimatsu, Hiroaki; Suzuki, Etsu; Nomiya, Akira; Niimi, Aya; Suzuki, Motofumi; Fujimura, Tetsuya; Fukuhara, Hiroshi; Homma, Yukio

    2013-07-01

    Erectile dysfunction (ED) is a major health problem. We have shown that adrenomedullin (AM) restores erectile function in diabetic rats. The aim of this study is to explore a better treatment for ED, we examined whether combination of AM and angiopoietin-1 (Ang-1) was more effective to treat ED than treatment with AM alone or Ang-1 alone. We also compared the effect of the combination therapy with that of treatment with vascular endothelial growth factor-A (VEGF-A). Male Wistar rats were injected with streptozotocin (STZ) to induce diabetes. Adenoviruses expressing AM (AdAM), Ang-1 (AdAng-1), and VEGF-A (AdVEGF-A) were injected into the penis 6 weeks after STZ administration. Erectile function, penile histology, and protein expression were analyzed 4 weeks after the injection of the adenoviruses. Intracavernous pressure and mean arterial pressure were measured to evaluate erectile function. The morphology of the penis was analyzed by Elastica van Gieson stain and immunohistochemistry. The expression of α-smooth muscle actin (SMA), VE-cadherin and type I collagen was assessed by Western blot analysis. Infection with AdAM plus AdAng-1 more effectively restored erectile function than infection with AdAM alone or AdAng-1 alone. This combination therapy restored erectile function to a level similar to that observed in the age-matched Wistar rats. Expression of SMA and VE-cadherin increased more significantly in the AdAM plus AdAng-1-treated group than in the AdAM- or AdAng-1-treated group. Although AdVEGF-A infection restored erectile function significantly, it also caused enlargement of the trabeculae of the cavernous body, aberrant angiogenesis, and overproduction of type I collagen. These results suggested that combination therapy with AM and Ang-1 potently restored erectile function and normal morphology of the cavernous body compared with VEGF-A administration. This combination therapy will be useful to treat ED patients with a severely damaged cavernous body.

  8. The Pulsed Neutron Technique Applied to Fast Non-Multiplying Assemblies; Application de la Methode des Neutrons Pulses aux Assemblages Non Multiplicateurs a Neutrons Rapides; Primenenie metoda impul'snykh nejtronov pri izuchenii povedeniya bystrykh nejtronov v nerazmnozhayushchikh sborkakh; Aplicacion de la Tecnica de los Neutrones Pulsados a Conjuntos Rapidos de Materiales No Multiplicadores

    Energy Technology Data Exchange (ETDEWEB)

    Beghian, L. E.; Wilensky, S. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    1965-10-15

    Boltzmann qui est fonction du temps (c'est-a-dire une dimension, une vitesse). Les constantes de decroissance ont ete mesurees pour des plaques de plomb de 70 cm x 80 cm et de 5, 10, 15 et 20 cm d'epaisseur. Apres correction pour tenir compte de la degradation en energie et des dimensions finies de l'assemblage, les resultats sont compares aux solutions approchees de l'equation de transport de Boltzmann. (author) [Spanish] Los autores han empleado un acelerador Van de Graafi, que emitia rafagas de neutrones pulsados del orden del nanosegundo, para estudiar el comportamiento de los neutrones rapidos en conjuntos de metales no multiplicadores. Emplearon esta tecnica de la fuente de neutrones pulsados a fin de medir las secciones eficaces de dispersion inelastica de los neutrones rapidos en el Fe. El metodo empleado es analogo al utilizado para medir las secciones eficaces de absorcion en conjuntos termicos, salvo el hecho de que los tiempos de decrecimiento de los neutrones rapidos son del orden del nanosegundo mas bien que del microsegundo. En estos experimentos, se inyectaron rafagas de neutrones monoenergeticos, del orden del nanosegundo, en conjuntos de Fe de diversas dimensiones. Se observo que, en esos conjuntos, el flujo neutronico decrece exponencialmente con una constante caracteristica. Esta constante de decrecimiento esta constituida por una suma de terminos que representan la perdida de neutrones debidos al escape y a la degradacion energetica. Esta ultima representa una perdida de neutrones toda vez que se emplea un detector neutronico polarizado. El termino de eliminacion correspondiente a la dispersion elastica e inelastica puede determinarse midiendo la constante de decrecimiento en funcion de las dimensiones del conjunto de que se trate. Los autores exponen un procedimiento teorico que permite calcular la medida en que la dispersion elastica contribuye al termino de eliminacion, con lo que puede calcularse subsiguientemente la seccion eficaz de dispersion

  9. Importance of the planning activities, cutting, handling and analysis of the nuclei of oil well drilling; Importancia de las actividades de planificacion, corte, manejo y analisis de los nucleos de perforacion de pozos petroleros

    Energy Technology Data Exchange (ETDEWEB)

    Contreras L, Enrique A; Garcia M, Pablo [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2007-07-01

    , recipientes de almacenamiento de hidrocarburos, agua y energia calorifica, asi como barreras impermeables y medios de transporte de la energia y de los fluidos. Entre las propiedades mas importantes que se utilizan para describir estas funciones se encuentran la porosidad, la permeabilidad, la compresibilidad del volumen de poros, el factor de resistividad de la formacion, el exponente de saturacion, la velocidad de las ondas acusticas P y S, las permeabilidades relativas, las presiones capilares, las constantes elasticas y otras propiedades mecanicas, el coeficiente de dilatacion termica, la conductividad termica, la difusividad termica y el calor especifico. La ejecucion de una amplia variedad de actividades relacionadas con las etapas de exploracion, localizacion, evaluacion y desarrollo de los yacimientos petroleros, depende fuertemente de que se tenga un buen conocimiento de la magnitud y de la variabilidad espacial de estas propiedades. Tanto la factibilidad tecnica como la economica de desarrollar un prospecto de yacimiento petrolero, dependen de que las rocas que intervienen exhiban una combinacion adecuada de sus propiedades, para asi constituir una estructura geologica confinante y almacenadora de hidrocarburos, que sea factible de desarrollarse tecnicamente, a la vez que tenga el potencial de redituar un beneficio economico. En este contexto, desde la plataforma de experiencia que se tiene sobre el tema en el Laboratorio de Yacimientos del Instituto de Investigaciones Electricas. En el presente articulo se aborda la relevancia que tienen las actividades de corte, manejo y analisis de laboratorio de los nucleos de perforacion de pozos petroleros, para la evaluacion de las formaciones geologicas, en relacion con la caracterizacion, la evaluacion y el aprovechamiento de los yacimientos petroleros.

  10. Evaluation of irradiated essential oils to control of Sitophilus zeamais Mots. (Coleoptera: Curculionidae) and Blatella germanica (L.) (Dictyopera: Blattellidae); Avaliacao de produtos naturais irradiados para o controle de Sitophilus zeamais Mots. (Coleoptera: Curculionidae) e Blatella germanica (L.) (Dictyopera: Blattellidae)

    Energy Technology Data Exchange (ETDEWEB)

    Potenza, Marcos Roberto

    2004-07-01

    This work aimed to evaluate the effect of irradiated essential oils of Eucalyptus citriodora, Eucalyptus globulus, Pinus sp., Azadirachta indica, Cymbopogon nardus, Cupressus sempervirens, Cymbopogons citratus and Juniperus communis and aqueous, hexanic and ethanolic irradiated extracts of Solanum paniculatum, Dahlia pinnata, Lycopersicon esculentum, Nephrolepis pectinata, Ruta graveolens, Ficus elastica, Lavandula angustifolia, Rhododendron simsii, Agave angustifolia, Ocimum basilicum, Allamanda cathartica, Dieffenbachia brasiliensis, Pennisetum purpureum, Annona squamosa, Coffea arabica and Hibiscus rosa-sinensis, in order to identify new substances to integrated pest management (IPM) and to observe possible effects of gamma radiation about extracts and essential oils efficiency such as increase, reduction, activation and inactivation of the same to the pest control. It evaluated the effect of contact on Sitophilus zeamais and by ingestion in Blattella germanica. To irradiation was used an experimental irradiator of Cobalt-60, type Gammacell 220. The essential oils were submitted increasing doses of gamma radiation: 2.5; 5.0; 7.5 and 10.0 kGy. The bioassay with B. germanica demonstrated efficiency between 22.0 e 30.0% and between 30.0 and 42.0%, respectively, to irradiated essential oils of E. citriodora and E. globulus and they demonstrated too repellency to the nymphs. The gamma radiation used promoted changes in essential oils of E. citriodora e E. globulus that they began to show efficiency on B. germanica nymphs besides a significant reduction of repellency. Essential oils of Pinus sp., A. indica, C. sempervirens and J. communis did not display efficiency. The essential oils of C. nardus, and C. citratus had low efficiency. The gamma radiation increased the efficiency of ethanolic extract of D. Pinnata with dose of 7.5 kGy, showing 48.0% of efficiency on B. germanica nymphs. The gamma radiation showed adverse effect on the aqueous extract of R. Graveolens

  11. Evaluation of irradiated essential oils to control of Sitophilus zeamais Mots. (Coleoptera: Curculionidae) and Blatella germanica (L.) (Dictyopera: Blattellidae); Avaliacao de produtos naturais irradiados para o controle de Sitophilus zeamais Mots. (Coleoptera: Curculionidae) e Blatella germanica (L.) (Dictyopera: Blattellidae)

    Energy Technology Data Exchange (ETDEWEB)

    Potenza, Marcos Roberto

    2004-07-01

    This work aimed to evaluate the effect of irradiated essential oils of Eucalyptus citriodora, Eucalyptus globulus, Pinus sp., Azadirachta indica, Cymbopogon nardus, Cupressus sempervirens, Cymbopogons citratus and Juniperus communis and aqueous, hexanic and ethanolic irradiated extracts of Solanum paniculatum, Dahlia pinnata, Lycopersicon esculentum, Nephrolepis pectinata, Ruta graveolens, Ficus elastica, Lavandula angustifolia, Rhododendron simsii, Agave angustifolia, Ocimum basilicum, Allamanda cathartica, Dieffenbachia brasiliensis, Pennisetum purpureum, Annona squamosa, Coffea arabica and Hibiscus rosa-sinensis, in order to identify new substances to integrated pest management (IPM) and to observe possible effects of gamma radiation about extracts and essential oils efficiency such as increase, reduction, activation and inactivation of the same to the pest control. It evaluated the effect of contact on Sitophilus zeamais and by ingestion in Blattella germanica. To irradiation was used an experimental irradiator of Cobalt-60, type Gammacell 220. The essential oils were submitted increasing doses of gamma radiation: 2.5; 5.0; 7.5 and 10.0 kGy. The bioassay with B. germanica demonstrated efficiency between 22.0 e 30.0% and between 30.0 and 42.0%, respectively, to irradiated essential oils of E. citriodora and E. globulus and they demonstrated too repellency to the nymphs. The gamma radiation used promoted changes in essential oils of E. citriodora e E. globulus that they began to show efficiency on B. germanica nymphs besides a significant reduction of repellency. Essential oils of Pinus sp., A. indica, C. sempervirens and J. communis did not display efficiency. The essential oils of C. nardus, and C. citratus had low efficiency. The gamma radiation increased the efficiency of ethanolic extract of D. Pinnata with dose of 7.5 kGy, showing 48.0% of efficiency on B. germanica nymphs. The gamma radiation showed adverse effect on the aqueous extract of R. Graveolens

  12. Evaluation of irradiated essential oils to control of Sitophilus zeamais Mots. (Coleoptera: Curculionidae) and Blatella germanica (L.) (Dictyopera: Blattellidae)

    International Nuclear Information System (INIS)

    Potenza, Marcos Roberto

    2004-01-01

    This work aimed to evaluate the effect of irradiated essential oils of Eucalyptus citriodora, Eucalyptus globulus, Pinus sp., Azadirachta indica, Cymbopogon nardus, Cupressus sempervirens, Cymbopogons citratus and Juniperus communis and aqueous, hexanic and ethanolic irradiated extracts of Solanum paniculatum, Dahlia pinnata, Lycopersicon esculentum, Nephrolepis pectinata, Ruta graveolens, Ficus elastica, Lavandula angustifolia, Rhododendron simsii, Agave angustifolia, Ocimum basilicum, Allamanda cathartica, Dieffenbachia brasiliensis, Pennisetum purpureum, Annona squamosa, Coffea arabica and Hibiscus rosa-sinensis, in order to identify new substances to integrated pest management (IPM) and to observe possible effects of gamma radiation about extracts and essential oils efficiency such as increase, reduction, activation and inactivation of the same to the pest control. It evaluated the effect of contact on Sitophilus zeamais and by ingestion in Blattella germanica. To irradiation was used an experimental irradiator of Cobalt-60, type Gammacell 220. The essential oils were submitted increasing doses of gamma radiation: 2.5; 5.0; 7.5 and 10.0 kGy. The bioassay with B. germanica demonstrated efficiency between 22.0 e 30.0% and between 30.0 and 42.0%, respectively, to irradiated essential oils of E. citriodora and E. globulus and they demonstrated too repellency to the nymphs. The gamma radiation used promoted changes in essential oils of E. citriodora e E. globulus that they began to show efficiency on B. germanica nymphs besides a significant reduction of repellency. Essential oils of Pinus sp., A. indica, C. sempervirens and J. communis did not display efficiency. The essential oils of C. nardus, and C. citratus had low efficiency. The gamma radiation increased the efficiency of ethanolic extract of D. Pinnata with dose of 7.5 kGy, showing 48.0% of efficiency on B. germanica nymphs. The gamma radiation showed adverse effect on the aqueous extract of R. Graveolens

  13. New Methods and Facilities for the Measurement of Physical Properties of Reactor Components and Irradiated Materials; Nouveaux Procedes et Instruments de Mesure des Proprietes Physiques des Elements de Reacteur et des Matieres Irradiees; Novye metody i sredstva izmereniya fizicheskikh s vojstv komponentov reaktora i obluchennykh materialov; Nuevos Metodos y Equipos para Medir Propiedades Fisicas de Componentes de Reactor y de Materiales Irradiados

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, F.; Mueller, P. [Institut Dr. Foerster, Reutlingen, Federal Republic of Germany (Germany)

    1965-09-15

    radiactivas a temperaturas comprendidas entre 20 y 1 000 Degree-Sign C. Los autores discuten el control de calidad de metales no ferrosos por medida de la conductividad electrica aplicando corrientes de Foucault. Se describe un instrumento para medir la conductividad electrica de metales no ferrosos sin utilizar elementos en contacto. Se explica la correlacion entre la conductividad electrica y las caracteristicas de esfuerzo-deformacion de metales y aleaciones no ferrosos. Se presta especial atencion a la determinacion de estas propiedades en muestras pequenas. Se describe un dispositivo para medicion directa a distancia en la zona radiactiva del reactor. Se examina la relacion existente entre conductividad electrica y la dosis de radiacion. Se describe un instrumento para medir la permeabilidad, la remanencia y la fuerza coercitiva en funcion de la-solicitacion mecanica y la deformacion elastica y plastica, como tambien de la dosis de radiacion. Se expone un metodo para medir la variacion de las propiedades magneticas en funcion de la solicitacion elastica y la deformacion plastica. Se discuten los efectos de la irradiacion sobre la permeabilidad y la fuerza coercitiva. Se describe un instrumento para medicion rapida e indicacion directa de la permeabilidad de componentes de acero inoxidable. Se explica la correlacion entre permeabilidad y contenido de {Delta} - ferrita. Se exponen las mediciones del porcentaje de {Delta} - ferrita en soldaduras practicadas en tubos de acero inoxidable, y de las precipitaciones de {Delta}-ferrita en funcion de la deformacion plastica (forjado de los elementos combustibles). (author) [Russian] Opisan pribor dlja avtomaticheskogo izmerenija i registracii modulja Junga, modulja sdviga i kojefficienta zatuhanija kak funkcii temperatury i vremeni. Izmerenie modulja Junga proizvoditsja s pomoshh'ju vozbuzhdennyh obrazcov razlichnyh razmerov pri ih estestvennoj chastote. Izmerenie kojefficienta zatuhanija proizvoditsja po svobodnomu zatuhaniju

  14. A punched-card library of neutron cross-sections and its use in the mechanized preparation of group cross-sections for use in Monte Carlo, Carlson S{sub n} and other multi-group neutronics calculations on high-speed computers

    Energy Technology Data Exchange (ETDEWEB)

    Parker, K [Atomic Weapons Research Establishment, Aldermaston (United Kingdom)

    1962-03-15

    constantes de groupes pour reproduire des mesures integrales et la simplification d'une serie de constantes pour un grand nombre de groupes en vue d'obtenir une serie de constantes pour un petit nombre de groupes. (author) [Spanish] La memoria describe el fichero de tarjetas perforadas sobre las que se registran en el Atomic Weapons Research Establishment (AWRE) las secciones eficaces neutronicas, asi como los programas correspondientes de la calculadora IBM-7090 que se emplean para la elaboracion de estos datos con miras a obtener promedios por grupo de secciones eficaces apropiadas para calculos neutronicos de grupos multiples por los metodos de Montecarlo, de S{sub n} de Carlson y otros procedimientos. El autor expone seguidamente los metodos desarrollados para estudiar la dispersion elastica isotropica y anisotropica. Comprenden la aproximacion de transporte de grupos multiples y el tratamiento completo de la dispersion anisotropica empleando los momentos polinomicos de Legendre de la matriz de transferencia por dispersion. El trabajo expone los principios de la formacion de constantes de grupo y, a titulo ilustrativo, describe sistemas de constantes de grupo que sirven para calculos de reactores rapidos. Analiza algunos problemas practicos como la adaptacion empirica de las constantes de grupo para reproducir resultados de mediciones integrales, y la reduccion de un sistema de constantes de muchos grupos a otro de pocos grupos. (author) [Russian] V doklade daetsya opisanie nakho-dyashchejsya v Nauchno-issledovatel'sko m tsentre po razrabotke atomnogo oruzhiya biblioteki perforirovannykh kartochek sechenij nejtronov sovmestno s programmami IBM 7090, kotorye obrabatyvayut ehti dannye dlya polucheniya usrednennykh po gruppam sechenij, kotorye ispol'zuyutsya v nejtronnykh vychisleniyakh po metodam Monte Karlo, Karlsona S{sub n} i v drugikh mnogogruppovykh vychisleniyakh. Opisyvayutsya metody, kasayushchiesya kak izotropnogo, tak i anizotropnogo uprugogo rasseyaniya. Oni

  15. Inelastic Neutron Scattering from Doped Germanium and Silicon; Diffusion Inelastique des Neutrons dans du Germanium et du Silicium Contenant une 'Impurete'; Neuprugoe rasseyanie nejtronov na germanii i kremnii s prisadkoj; Dispersion Inelastica de Neutrones en Germanio y Silicio Deliberadamente Impurificados

    Energy Technology Data Exchange (ETDEWEB)

    Dolling, G. [Chalk River Nuclear Laboratories, Chalk River, ON (Canada)

    1965-04-15

    'environ 0,5% pour la frequence et elle atteint 2, 0 Degree-Sign jo pour certains modes optiques longitudinaux dans le silicium. (author) [Spanish] Los modos normales de vibracion de los semiconductores germanio y silicio puros se han estudiado ampliamente por dispersion monofononica coherente de neutrones lentos en muestras monocristalinas. En la memoria se describen experimentos analogos realizados utilizando: 1) germanio deliberadamente impurificado ( Tilde-Operator 0,1%) con a) arsenico y b) galio; 2) silicio impurificado con fosforo. Se realizaron siempre experimentos testigo con cristales de elevada pureza. Todas las mediciones se llevaron a cabo con el espectrometro triaxial de cristal instalado en los Chalk River Nuclear Laboratories. Como es sabido, la constante elastica C{sub 44}, correspondiente al germanio depende sensiblemente de la concentracion de la impureza* por lo que se estudiaron ciertos modos acusticos transversales de onda larga para comprobar si tales efectos persistian en la region dispersiva. En ambos materiales se estudiaron tambien otros modos acusticos transversales de frecuencia susceptible de medirse con gran precision, a fin de observar con el mayor detenimiento posible los leves efectos que pudiera atribuirse a la existencia de electrones o vacantes en exceso. Se estudiaron con particular cuidado los modos que tienen los vectores de onda (aq/2{pi}, en donde a es la arista de la celdilla unidad cubica): a) en el germanio (1,0,0), y b) en el silicio (0, 85, 0,85, 0) y (0,3, 0, 0). Cabria esperar que estos modos normales tuviesen un comportamiento anomalo en los cristales de tipo n, pues la dispersion intervalle de electrones entre minimos adyacentes de bandas de conduccion exigiria su cooperacion para conservar . Los resultados fueron negativos en todos los casos, esto es, no se observo diferencia alguna de frecuencias fononicas ni de amplitudes de energia entre muestras puras e impurificadas, dentro del margen de error

  16. Comparative Studies of Chemical Effects following Nuclear Reactions and Transformations on Metal Organic Phenyl Compounds; Etudes Comparatives des Effets Chimiques Induits par les Reactions et les Transformations Nucleaires sur des Composes Phenylmetalliques; 0421 0420 0410 0414 ; Estudios Comparativos de los Efectos Quimicos de las Reacciones y Transformaciones Nucleares en Compuestos Fenil-Organometalicos

    Energy Technology Data Exchange (ETDEWEB)

    Merz, E.; Riedel, H. J. [Kernforschungsanlage, Juelich, Federal Republic of Germany (Germany)

    1965-04-15

    retroceso secundarios (interacciones elasticas e inelasticas), entre ellas la influencia peculiar del oxigeno. (author) [Russian] Izuchenie himicheskih jeffektov, sozdavaemyh v processe jadernyh reakcij atomami otdachi bol'shoj jenergii v tverdyh telah i zhidkostjah, provodilos' na osnovanii shirokogo sopostavlenija produktov, obrazovannyh reakcijami (p,{gamma}) i (p, 2p) v soedinenijah fenila s metallami , kak to: germaniem, olovom, svincom, mysh'jakom i sur'moj. V dopolnenie k jetomu radioaktivnye produkty otdachi, obrazovannye posle K-zahvata na tetrafenile germanija-68, sravnivajutsja s rezul'tatami reakcii (p,7) na trifenile gallija i reakcii (p, {gamma}) na tetrafenile germanija. Nakonec, jeto issledovanie rasprostranilos' na {beta}{sup -}-perehod tetrafenila germanija-77 v mysh'jak-77. S pomoshh'ju razlichnyh metodov otdelenija, naprimer, hromatografii adsorbcii na glinozeme, ionnogo obmena i jelektroforeza byli otdeleny razlichnye radioaktivnye produkty otdachi i opredeleny vyhody kazhdogo iz nih. Ustanovleno, chto v jadernyh reakcijah soedinenij vysheupomjanutyh metallov, imejushhih odinakovuju strukturu svjazej, obrazujutsja pochti te zhe kategorii produktov otdachi. Odnako raspredelenie vyhodov obnaruzhivaet harakternye rashozhdenija mezhdu reakcijami (p,{gamma}) i reakcijami (p, 2p). Obnaruzhivaetsja tol'ko neznachitel'noe vlijanie obluchenija na vyhody pri vozdejstvii ego sootvetstvenno na zhidkosti i rastvory. Porazhajut znachitel'nye rashozhdenija, obnaruzhivaemye dlja novyh soedinenij, poluchennyh v rezul'tate jadernyh prevrashhenij; jeti rashozhdenija kasajutsja ne tol'ko vida tipichnyh produktov, no takzhe i procentnoj doli ih vyhoda. Tak, naprimer, rjad produktov otdachi germanija i gallija metalloorganicheskogo haraktera byli obnaruzheny v jadernyh reakcijah na tetrafenile germanija-77, chego vovse ne nabljudalos' pri processah K-zahvata na tetrafenile germanija-68. {beta}{sup -}-raspad na tetrafenile germanija-77 vedet k obrazovaniju pochti takih zhe

  17. The luminescent chamber and its use in high-energy physics experiments; La chambre a luminescence: son emploi dans les experiences de physique des hautes energies; Lyuminestsentnaya kamera i ee ispol'zovanie v ehksperimentakh, provodimykh v fizike vysokikh ehnergij; La camara luminiscente y su empleo en experimentos de fisica de elevada energia

    Energy Technology Data Exchange (ETDEWEB)

    Jones, L W; Perl, M L [Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI (United States); Lawrence Radiation Laboratory, University of California, Berkeley, CA (United States)

    1962-04-15

    electronique du compteur a scintillations. Les auteurs exposent les travaux de preparation et d'execution qui ont ete necessaires pour mener ces experiences a bonne fin; ils donnent, en particulier, les details voulus sur les tubes a rayons cathodiques, les compteurs a scintillations et les systemes electroniques utilises. L'analyse de photographies de trajectoires leur a permis d'etudier, notamment, le degre de precision qui peut etre atteint et la valeur des resultats physiques qui peuvent etre obtenus. Enfin, ils explorent les possibilites de developpement qui s'offrent a la chambre a luminescence, compte tenu des tubes renforcateurs d'image et des scintillateurs actuellement a l'etude. Ils analysent le role que la chambre a luminescence est appelee a jouer a l'avenir dans les experiences du domaine des grandes energies en comparaison avec la chambre a etincelles et les autres detecteurs. (author) [Spanish] Por primera vez se ha empleado una camara luminescente en experimentos de fisica con particulas de elevada energia. En el Bevatron del Lawrence Radiation Laboratory se fotografiaron trazas de particulas en cristales de yoduro sodico activado por medio de un sistema en cascada de tres tubos intensificadores de imagen. En un experimento se estudio la dispersion elastica pion-proton utilizando dos conjuntos de centelladores, cada uno de 20 cm de longitud. Uno para observar el pion dispersado y, el otro, el proton de retroceso procedente de un blanco de hidrogeno liquido. Los contadores de centelleo seleccionaban unicamente los sucesos casi coplanares que habian de ser registrados; no obstante, respecto de la dispersion inelastica, el criterio definitivo era la cinematica de las trazas registradas. Se fotografiaron alrededor de 1000 sucesos elasticos correspondientes cada uno a tres cantidades de movimiento del pion incidente hasta 2,5 MeV/c. En un segundo experimento se utilizo unicamente un conjunto de centelleadores de 10 x 10 x 20 cm{sup 3} para observar el frenado de

  18. Investigation of the Dynamics Of NH{sup +}{sub 4} and H{sub 2}O Molecular Groups in Crystals; Etude de la Dynamique des Groupes Moleculaires NH{sup +}{sub 4} et H{sub 2}O dans les Cristaux; 0418 0421 0421 041b 0415 0414 041e 0412 0410 041d 0418 0415 0414 0418 041d 0410 041c 0418 041a 0418 041c 041e 041b 0415 041a 0423 041b 042f 0420 041d 042b 0425 0413 0420 0423 041f 041f NH{sup +}{sub 4} H H{sub 2}O 0412 041a 0420 0418 0421 0422 0410 041b 041b 0410 0425 ; Estudio de la Dinamica de los Grupos Moleculares NH{sup +}{sub 4} Y H{sub 2}O en Cristales

    Energy Technology Data Exchange (ETDEWEB)

    Bajorek, A.; Machehina, T. A.; Parlin' Ski, K. [Ob' edinennyj Institut Jadernyh Issledovanij, Dubna, SSSR (Russian Federation)

    1965-06-15

    investigaciones era estudiar la influencia ejercida por las distintas redes cristalinas sobre la dinamica de los mencionados grupos, y la relacion existente entre los procesos de dispersion y las transiciones de fase. A pesar de la distinta estructura de las sustancias estudiadas, los espectros obtenidos a la temperatura del nitrogeno liquido son analogos; por regla'general, se observan dos picos: el primero en la region de transferencia energetica de 15 a 20 meV, el segundo en la region correspondiente a 35-70 meV, que esta relacionado con las oscilaciones de torsion de los iones amonio. La intensidad de los picos, que depende de la estructura de las sustancias estudiadas, disminuye al aumentar la temperatura de la muestra. Se observo que la intensidad de la parte elastica del espectro, en ciertas transiciones de fase, presenta discontinuidades (en los casos del NH{sub 4}I, NH{sub 4}NO{sub 3} y (NH{sub 4}){sub 2}SO{sub 4}). Al aumentar la temperatura del NH{sub 4}Cl, NH{sub 4}Br y (NH{sub 4}){sub 2}(COO){sub 2}, aparece otro pico, desplazado hacia las energias mas bajas con respecto a los picos de rotacion restringida. ' Los espectros correspondientes a los neutrones dispersos en cristales que contienen agua de cristalizacion tambien presentan analogias. Se observaron tres grupos de picos, asociados a las oscilaciones opticas y a la rotacion restringida de las moleculas de agua. (author) [Russian] V doklade predstavleny rezul'taty izmerenij rassejanija teplovyh nejtronov na kristallah, soderzhashhih ammonievyj ion (NH{sub 4}CI, NH{sub 4}Br, NH{sub 4}I, NH{sub 4}F, NH{sub 4}NO{sub 3}, NH{sub 4}CNS, (NH{sub 4}){sub 2}SO{sub 4}, (NH{sub 4}){sub 2}S{sub 2}O{sub 8}, (NH{sub 4}){sub 2}Cr{sub 2}O{sub 7}, (NH{sub 4}){sub 2}CO{sub 3}) i kristallizacionnuju vodu (BaCl{sub 2} * 2H{sub 2}O, SrCl{sub 2} * 6H{sub 2}O, CuSO{sub 4} * 5H{sub 2}O). Cel'ju issledovanija bylo izuchenie vlijanija razlichnyh kristallicheskih reshetok na dinamiku ukazannyh grupp, i svjazi processov rassejanija s

  19. Recent Methods in Crystal Spectrometry; Methodes Recentes de Spectrometrie a Cristal; 041d 041e 0412 042b 0415 041c 0415 0422 041e 0414 042b 041a 0420 0418 0421 0422 0410 041b 041b 0418 0427 0415 0421 041a 041e 0419 0421 041f 0415 041a 0422 0420 041e 041c 0415 0422 0420 0418 0418 ; Metodos Recientes de Espectrometria Cristalina

    Energy Technology Data Exchange (ETDEWEB)

    Iyengar, P. K. [Atomic Energy Establishment Trombay, Bombay (India)

    1965-06-15

    parti de la definition en vecteur d'onde des neutrons deceles, l'auteur a utilise avec succes le filtre a fenetre pour determiner les courbes de dispersion des phonons dans des reseaux cristallins. Un instrument biaxial remplacant un instrument triaxial, il en resulte une simplification de l'appareillage. Avec ce dispositif, l'auteur a applique la methode de Q constant. Il presente certaines mesures caracteristiques. Le principal inconvenient de la methode de la spectrometrie a cristal reside dans le fait que l'on n'utilise qu'un angle de diffusion a la fois. On peut le pallier un utilisant un spectrometre a bras multiples. L'auteur montre comment monter et utiliser un spectrometre a bras multiples pour les mesures, de la distribution en energie. D'autre part, l'avantage de l'etude d'echantillons monocristaux reside dans le fait qu'il est possible d'utiliser tous les bras avec les spectrometres d'analyse dans le mode de Q constant. Cela permettrait d'accelerer considerablement le rassemblement des donnees a l'avenir en appliquant la methode du spectrometre a cristal. (author) [Spanish] El principio de la difraccion por cristales permite evaluar de manera sencilla la distribucion de energia de los neutrones lentos. Pero la determinacion cuantitativa de esa distribucion de energia depende de varios parametros, que son a su vez funcion de la estructura de la celda unitaria del cristal monocromador y de la disposicion geometrica del espectrometro. El espectrometro triaxial se utiliza ampliamente para trabajos de dispersion inelastica. Esta provisto de un monocromador y de un analizador cristalinos. La disposicion geometrica y la dispersion debida a la variacion no lineal del angulo con la longitud de onda originan efectos de focalizacion. Este aspecto se examina en relacion con varios casos, tales como dispersion elastica y existencia de grupos de neutrones debidos a interaccion de monofonones. Se ha empleado como analizador de gran eficacia un filtro policristalino

  20. Diffuse Scattering from Alloys and Disordered Systems: Experimental Techniques and Potentialities; Diffusion dans les Alliages et les Systemes Desordonnes; Methodes Experimentales et Possibilites d'Application; Diffuznoe rasseyanie na splavakh i razuporyadochennykh sistemakh. ehksperimental'nye metody i potentsial'nye vozmozhnosti; Dispersion Difusa en Aleaciones y Sistemas Desordenados; Tecnicas Experimentales y Posibilidades

    Energy Technology Data Exchange (ETDEWEB)

    Low, G. G. [Atomic Energy Research Establishment, Harwell, Berks (United Kingdom)

    1965-04-15

    magnetique. On parvient a l'eviter en utilisant un echantillon monocristal ou en employant des neutrons ayant une longueur d'onde suffisante pour qu'aucun phenomene de Bragg ne puisse se produire. Un appareil fonde sur ce dernier principe a ete mis au point a Harwell et utilise pour une gamme etendue de mesures portant sur des alliages ferromagnetiques dilues. L'auteur discute ces travaux ainsi que plusieurs autres qui pourraient etre entrepris dans ce domaine. Parmi ces derniers figurent des mesures de la diffusion magnetique par les sels paramagnetiques. L'observation de cette diffusion revet un grand interet car elle fournit des renseignements directs sur la fraction de spin transferee, par suite de la covalence, d'un ion magnetique aux coordinats qui l'entourent. (author) [Spanish] La finalidad de la memoria es analizar, desde el punto de vista de la teoria y de la practica, las informaciones que pueden obtenerse estudiando la dispersion elastica difusa de neutrones. Se presta particular atencion a los sistemas con distribucion aleatoria de defectos, cada uno de los cuales puede considerarse aislado de los demas, bien por efecto de la dilucion o bien por ser intrinsecamente independiente del medio. En estas condiciones, la intensidad dispersa es proporcional al cuadrado del modulo de una transformada de Fourier respecto de la perturbacion de la amplitud de dispersion asociada al defecto. De este modo pueden obtenerse datos sobre la distribucion espacial de la amplitud de dispersion por defectos realizando las mediciones pertinentes por dispersion neutronica y efectuando una inversion de Fourier. En la practica, dada la gran cantidad de procesos que contribuyen a la actividad de fondo debida a la dispersion difusa, solo se han podido realizar determinados tipos de mediciones. En particular, se han logrado progresos considerables en lo que respecta a los defectos magneticos de las sustancias ferromagneticas en las que la seccion eficaz magnetica puede controlarse cambiando