scholarly journals Pressure-induced depolymerization of spindle microtubules. I. Changes in birefringence and spindle length.

1975 ◽  
Vol 65 (3) ◽  
pp. 603-614 ◽  
Author(s):  
E D Salmon
Keyword(s):  
Initial Phase ◽  
Polarized Light ◽  
Meiotic Metaphase ◽  
Second Phase ◽  
Complete Disappearance ◽  
Spindle Microtubule ◽  
Spindle Microtubules ◽  
Optical Pressure ◽  
Two Phases ◽  
Kinetics Of

Changes in birefringence retardation (BR) and length of Chaetopterus meiotic metaphase-arrested spindles produced by increased hydrostatic pressure were observed with polarized-light microscopy using a newly developed optical pressure chamber. Increased pressure produced rapid, reversible decreases in spindle BR and length. Pressures of 3,500 psi or higher at 22 degrees C caused complete disappearance of spindle BR within 3 min. Up to 6,000 psi, the rates of both BR decay and spindle shortening increased progressively with increasing pressure. At 6,000 psi or above, the BR decreased rapidly but there was no evidence of spindle shortening. The general observations are consistent with results of earlier classical experiments on effects of pressure on mitosis, and with experiments that used colchicine or low temperature as microtubule-depolymerizing agents. The kinetics of spindle depolymerization and repolymerization showed two phases: an initial phase of rapid decreases or increase in half-spindle microtubule BR; and a second phase of nearly constant BR during which most of the spindle shortening or growth occurs. BR is assumed to be directly related to the number of microtubules in a spindle cross section. It is hypothesized that microtubules in the spindle have different stabilities depending on the attachment of nonattachment of their ends. This hypothesis is used to explain the two phases of spindle depolymerization and repolymerization as well as several other observations.

The Roman Road-Station at Thenadassa (Ain Wif)

1982 ◽  
Vol 13 ◽  
pp. 73-80 ◽  
Author(s):  
D. J. Mattingly
Keyword(s):  
Initial Phase ◽  
Indigenous Population ◽  
Second Century ◽  
Third Century ◽  
Second Phase ◽  
The Third ◽  
Military Presence ◽  
Two Phases ◽  
The Military ◽  
New Evidence

AbstractA reappraisal of the Roman period ruins at Ain Wif has been made following the identification there of traces of defensive walls. These walls are interpreted as being the robbed-out remains of a Roman fortlet and possibly also a tort on the same site. Two phases of military occupation were also evident in modern drain trenches being cut across the site and are attested epigraphically for the military bath-house by the spring. Ceramic evidence from the site suggests that the initial phase lies within the second century, whilst the Severan occupation, known from an inscription to begin early in the third century, represents a second phase. The previous view of the site as an undefended road-station, with a military presence only under the Severan emperors is no longer tenable. Moreover, the new evidence indicates that there was some measure of military organisation in the hinterland of the Emporia prior to the accession of Septimius Severus at the very end of the second century AD. The importance of the site also lies in its large civilian and indigenous population who continued to occupy the site long after the military had departed.

scholarly journals COMPARATIVE KINETICS OF HEMOLYSIS INDUCED BY BACTERIAL AND OTHER HEMOLYSINS

1947 ◽  
Vol 30 (4) ◽  
pp. 337-353 ◽  
Author(s):  
Alan W. Bernheimer
Keyword(s):  
Maximum Rate ◽  
Sodium Taurocholate ◽  
Second Phase ◽  
Pyridinium Chloride ◽  
Cetyl Pyridinium Chloride ◽  
Streptolysin S ◽  
Streptolysin O ◽  
Cetyl Pyridinium ◽  
Two Phases ◽  
Kinetics Of

A study has been made of the kinetics of lysis induced by various hemolytic agents. The course of bemolysis was followed by mixing lysin with washed human erythrocytes, removing samples from the mixture, and estimating colorimetrically the hemoglobin in the supernatant fluid of the centrifuged samples. Most of the curves (but not all of them, e.g. tyrocidine) obtained by plotting degree of hemolysis against time, were S-shaped. The initiation of lysis by streptolysin S' was delayed, and in this property, streptolysin S' was similar to Cl. septicum hemolysin. None of the other lysins studied exhibited a long latent period preceding lysis. The maximum rate of hemoglobin liberation was found, in the range of lysin concentrations studied, to be a linear function of concentration when theta toxin of Cl. welchii, pneumolysin, tetanolysin, or streptolysin S' was the lytic agent. With comparable concentrations of saponin, sodium taurocholate, cetyl pyridinium chloride, tyrocidine, duponol C, lecithin-atrox venom mixture, or streptolysin O, the relation between rate and concentration was non-linear. The critical thermal increment associated with hemolysis was determined for systems containing pneumolysin, theta toxin, streptolysin S', streptolysin O, tetanolysin, and saponin. The findings concerning the effect of concentration and temperature on the rate of hemolysis provide a basis for classifying hemolytic agents (Tables I and II). Hemolysis induced by Cl. septicum hemolysin was found to be preceded by two phases: a phase of alteration of the erythrocytes and a phase involving swelling. Antihemolytic serum inhibited the first but not the second phase while sucrose inhibited the second but not the first phase.

scholarly journals Magnetic relaxation and the Taylor conjecture

2015 ◽  
Vol 81 (6) ◽  
Author(s):  
H. K. Moffatt
Keyword(s):  
Magnetic Field ◽  
Initial Phase ◽  
Magnetic Relaxation ◽  
Magnetic Energy ◽  
Magnetic Pressure ◽  
Second Phase ◽  
One Dimensional ◽  
Induction Equation ◽  
Two Phases ◽  
The Magnetic Field

A one-dimensional model of magnetic relaxation in a pressureless low-resistivity plasma is considered. The initial two-component magnetic field $\boldsymbol{b}(\boldsymbol{x},t)$ is strongly helical, with non-uniform helicity density. The magnetic pressure gradient drives a velocity field that is dissipated by viscosity. Relaxation occurs in two phases. The first is a rapid initial phase in which the magnetic energy drops sharply and the magnetic pressure becomes approximately uniform; the helicity density is redistributed during this phase but remains non-uniform, and although the total helicity remains relatively constant, a Taylor state is not established. The second phase is one of slow diffusion, in which the velocity is weak, though still driven by persistent weak non-uniformity of magnetic pressure; during this phase, magnetic energy and helicity decay slowly and at constant ratio through the combined effects of pressure equalisation and finite resistivity. The density field, initially uniform, develops rapidly (in association with the magnetic field) during the initial phase, and continues to evolve, developing sharp maxima, throughout the diffusive stage. Finally it is proved that, if the resistivity is zero, the spatial mean $\langle (\boldsymbol{b}\boldsymbol{\cdot }\boldsymbol{{\rm\nabla}}\times \boldsymbol{b})/b^{2}\rangle$ is an invariant of the governing one-dimensional induction equation.

BODY HEAT STORAGE, METABOLISM AND RESPIRATION OF COWS ABRUPTLY EXPOSED AND ACCLIMATIZED TO COLD AND 18 °C ENVIRONMENTS

1984 ◽  
Vol 64 (3) ◽  
pp. 641-653 ◽  
Author(s):  
J. A. McLEAN ◽  
W. T. WHITMORE ◽  
B. A. YOUNG ◽  
R. WEINGARDT
Keyword(s):  
Initial Phase ◽  
Heat Storage ◽  
The Body ◽  
Second Phase ◽  
Mean Body Temperature ◽  
Cyclic Patterns ◽  
Cyclic Temperature ◽  
Two Phases ◽  
Body Heat ◽  
Effective Buffer

Six cows were alternated between cold (−30 to 0 °C) and 18 °C environments. Rectal (Tr), mean skin (Ts) and mean body (Tb = 0.86 Tr + 0.14 Ts) temperatures, respiration rate (RR) and metabolism per unit body size (M) were measured on first exposure and after acclimatization to each environment. Cows acclimatized to the cold had the same Tr as when acclimatized to 18 °C, but Ts and RR were lower and M was higher in the cold than in the 18 °C environment. Acclimatization appeared to occur in two phases. In the initial phase, lasting less than a day, new 24-h cyclic patterns (greater in the cold than in 18 °C) were established in body temperatures, respiration and metabolism. In the second phase which took longer than 2 days new levels were established in these parameters. The change in heat stored in the body between the two environments was not as great as previously found in an environment with a relatively small but cyclic temperature variation. It is suggested that changes in body heat storage are associated with cyclic or sudden changes in the environment, when it can act as an effective buffer against thermal stress. Key words: Cattle, mean body temperature, body heat storage, acclimatization

Oxidative Ammonolysis of Technical Lignins. Part 1. Kinetics of the Reaction under Isothermal Condition at 130°C

Holzforschung ◽  
2001 ◽  
Vol 55 (4) ◽  
pp. 397-404 ◽  
Author(s):  
Ewellyn A. Capanema ◽  
Mikhail Yu. Balakshin ◽  
Chen-Loung Chen ◽  
Josef S. Gratzl ◽  
Adrianna G. Kirkman
Keyword(s):  
Reaction Time ◽  
Isothermal Condition ◽  
Reaction Times ◽  
Molar Ratio ◽  
Second Phase ◽  
Spectroscopic Techniques ◽  
Oxidative Ammonolysis ◽  
Nitrogen Incorporation ◽  
Two Phases ◽  
Kinetics Of

Summary Investigations were conducted on the oxidative ammonolysis of REPAP organosolv lignin at 130 °C in 0.8M NH4OH solution under oxygen pressure of 12 bar. The lignin was completely solubilized at the reaction time of 165 min. The kinetics of the nitrogen incorporation consists of two phases. The first phase is up to the reaction time of approximately 35 min including 15 min heating up period. The rate of nitrogen incorporation in the first phase is 2.3 times higher than that in the second phase: κ1 = 4.58 × 10−4 s−1 versus κ2 = 1.90 × 10−4 s−1. The oxygen uptake and CO2 formation in the reaction is rather high. When the nitrogen incorporation was ceased after reaction for 255 minutes, more than 4 moles of oxygen/C9-unit of lignin were consumed and approximately 1.5 moles of carbon dioxide/C9-unit of lignin were released. In addition, extensive O-demethylation of methoxyl groups occurred. The molar ratio of the nitrogen incorporation to the methoxyl group eliminated is approximately 1.4 and 0.7 for the soluble and insoluble N-modified lignins, respectively. Structural analyses of the soluble N-modified lignins by FTIR and 1H NMR spectroscopic techniques showed only quantitative differences in the spectra obtained at different reaction times. This indicates that the reaction pathways do not change in the course of the oxidative ammonolysis. Possible reaction mechanisms of the oxidative ammonolysis are discussed on the basis of the experimental data.

Kinetic Studies on Oxidation of Veratryl Alcohol by Laccase-Mediator System. Part 2. The Kinetics of Dioxygen Uptake

Holzforschung ◽  
2000 ◽  
Vol 54 (2) ◽  
pp. 171-175 ◽  
Author(s):  
Mikhail Yu. Balakshin ◽  
Chen-Loung Chen ◽  
Josef S. Gratzl ◽  
Adrianna G. Kirkman ◽  
Harald Jakob
Keyword(s):  
Reaction Time ◽  
Initial Phase ◽  
Cation Radical ◽  
Kinetic Studies ◽  
Veratryl Alcohol ◽  
Second Phase ◽  
Stoichiometric Ratio ◽  
Rate Law ◽  
Order Rate ◽  
Kinetics Of

Summary The kinetics of dioxygen uptake in the laccase-catalyzed oxidation of veratryl alcohol with dioxygen in the presence of ABTS, the mediator, was studied. The kinetics of dioxygen uptake consists of two phases: (1) the initial phase up to a reaction time of one hour, and (2) the second phase, after a reaction time of one hour. In the initial phase, ABTS is mainly oxidized to the corresponding cation radical. The kinetics of dioxygen uptake follows a pseudo-zero order rate law. The dioxygen uptake under the reaction condition correlates with the initial ABTS concentration according to the stoichiometric relationship of 0.25 moles dioxygen per mole ABTS. In the second phase, veratryl alcohol is mainly oxidized to veratraldehyde. The kinetics of the dioxygen uptake follows a pseudo-first order rate law. The dioxygen uptake correlates linearly with the yield of veratraldehyde. The stoichiometric ratio between the formation of veratraldehyde and the consumption of dioxygen differs slightly at different M/S ratios. On average, however, it is 0.42 moles of dioxygen per one mole of veratraldehyde formed. The reaction mechanism is discussed on the basis of the kinetic data.

Microstructural Kinetics in Alloys Undergoing Transmutations: Application to Aic Neutron Absorbers

1996 ◽  
Vol 439 ◽  
Author(s):  
C. Desgranges ◽  
G. Martin ◽  
F. Defoort
Keyword(s):  
Grain Size ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Second Phase ◽  
Phase Precipitation ◽  
Water Reactors ◽  
Two Phases ◽  
Control Rods ◽  
Kinetics Of

AbstractWhenever an alloy changes composition because of metal to metal transmutations, as is the case in Ag-In-Cd alloys undergoing (n, −) actions in the control rods of Pressurised Water Reactors, unique features may develop.A simple model shows that in a two components alloy more than two phases can coexist under appropriate irradiation conditions i.e. temperature, which scales diffusivities and solubilities, and flux, which scales the transmutations rate; because second phase precipitation occurs at the grain boundaries, the grain size in the underlying matrix is found to be one important parameter of the process.The above ideas are illustrated on a multicomponent alloy, the thermodynamics and the kinetics of which are treated at the same level of sophistication in a mean field approximation.

Accurate Detection and Quantization of Leaf- Diseases through Soft Computing

2018 ◽  
Vol 1 (1) ◽  
pp. 236-247
Author(s):  
Divya Srivastava ◽  
Rajitha B. ◽  
Suneeta Agarwal
Keyword(s):  
Machine Learning ◽  
Image Processing ◽  
Agricultural Production ◽  
Bacterial Blight ◽  
Early Stage ◽  
Second Phase ◽  
Computationally Efficient ◽  
Stage Of Disease ◽  
Accurate Detection ◽  
Two Phases

Diseases in leaves can cause the significant reduction in both quality and quantity of agricultural production. If early and accurate detection of disease/diseases in leaves can be automated, then the proper remedy can be taken timely. A simple and computationally efficient approach is presented in this paper for disease/diseases detection on leaves. Only detecting the disease is not beneficial without knowing the stage of disease thus the paper also determine the stage of disease/diseases by quantizing the affected of the leaves by using digital image processing and machine learning. Though there exists a variety of diseases on leaves, but the bacterial and fungal spots (Early Scorch, Late Scorch, and Leaf Spot) are the most prominent diseases found on leaves. Keeping this in mind the paper deals with the detection of Bacterial Blight and Fungal Spot both at an early stage (Early Scorch) and late stage (Late Scorch) on the variety of leaves. The proposed approach is divided into two phases, in the first phase, it identifies one or more disease/diseases existing on leaves. In the second phase, amount of area affected by the disease/diseases is calculated. The experimental results obtained showed 97% accuracy using the proposed approach.

Representação e simbolismo: artes visuais na fronteira Brasil/Bolívia

2020 ◽  
Vol 4 (3) ◽  
pp. 286
Author(s):  
Paulo César Antonini de Souza ◽  
Derick Trindade Bezerra
Keyword(s):  
Visual Arts ◽  
Social Order ◽  
Research Field ◽  
Border Region ◽  
Second Phase ◽  
Two Dimensional ◽  
Santa Cruz ◽  
Cultural Conditions ◽  
Two Phases ◽  
America Latina

ResumoTendo por campo de investigação o Festival da América do Sul Pantanal (FASP) em 2018, na cidade de Corumbá (Brasil), objetiva-se identificar a materialidade e conceitos que permeiam as manifestações artísticas bidimensionais nesta região de fronteira, a partir da percepção de artistas da Bolívia. A pesquisa se organizou em duas fases: na primeira foi realizado um levantamento em plataformas online de produções acadêmicas em artes visuais, com foco no trabalho bidimensional, utilizando os descritores “arte popular” e “estética latina” resultando em três artigos. Na segunda fase foram selecionados dois trabalhos de uma artista da Bolívia, participante da mostra “Conexão Santa Cruz”, realizada durante o FASP 2018, que foram analisados em seus níveis representacional e simbólico. Pela interpretação das imagens foi possível construir uma leitura sobre a perspectiva da artista a respeito de suas condições culturais dentro da ordenação social em que se encontra situada.Palavras-chave: Artes Visuais. Arte Popular. Arte Regional. América Latina. Representation and symbolism: visual arts on the Brazil/Bolivia frontierAbstractHaving as research field the Festival da América do Sul Pantanal (FASP) in 2018, in the city of Corumbá (Brazil), the objective is to identify the materiality and concepts that permeate the two-dimensional artistic manifestations in this border region, from the perception of artists from Bolivia. The research was organized in two phases: in the first, a survey was carried out on online platforms of academic productions in visual arts, focusing on two-dimensional work, using the descriptors “arte popular” and “estética latina” resulting in three articles. In the second phase, two works were selected by an artist from Bolivia, participating in the exhibition “Conexão Santa Cruz”, held during FASP 2018, which were analyzed at their representational and symbolic levels. Through the interpretation of the images, it was possible to construct a reading on the artist’s perspective regarding her cultural conditions within the social order in which she is located.Keywords: Visual Arts. Folk Art. Regional Art. Latin America.Representación y simbolismo: artes visuales en la frontera de Brasil/BoliviaResumenTeniendo como campo de investigación el Festival de Sudamérica Pantanal (FASP) en 2018, en la ciudad de Corumbá (Brasil), el objetivo es identificar la materialidad y conceptos que permean las manifestaciones artísticas bidimensionales en esta región fronteriza, desde la percepción de artistas de Bolivia. La investigación se organizó en dos fases: en la primera, se realizó una encuesta en plataformas online de producciones académicas en artes visuales, con foco en el trabajo bidimensional, utilizando los descriptores “arte popular” y “estética latina” dando como resultado tres artículos. En la segunda fase, dos obras fueron seleccionadas por un artista de Bolivia, participante de la exposición “Conexão Santa Cruz”, realizada durante FASP 2018, que fueron analizadas en sus niveles representativos y simbólicos. A través de la interpretación de las imágenes, fue posible construir una lectura sobre la perspectiva de la artista sobre sus condiciones culturales dentro del orden social en el que se ubica.Palabras clave: Artes Visuales. Arte Popular. Arte Regional. América Latina.

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