Variability, Spatial Patterns and Scales of Similarity in Size–Frequency Distributions of the Northern Shrimp (Pandalus borealis) and its Migrations in the Gulf of St. Lawrence

1990 ◽  
Vol 47 (4) ◽  
pp. 794-804 ◽  
Author(s):  
Yvan Simard ◽  
Louise Savard
Keyword(s):  
Spatial Organization ◽  
Relative Proportion ◽  
Growth Increment ◽  
Migration Routes ◽  
Frequency Distributions ◽  
Depth Migration ◽  
Spatial Gradients ◽  
Northern Shrimp ◽  
Wide Range ◽  
Increasing Temperature

The causes of high variability of length–frequency distributions (LFDs) of the northern shrimp in the Gulf of St. Lawerence were investigated with spatial statistics. The LFD is considered as a multivariate whose spatial structure was analyzed with cluster analysis, dissimilarity variograms and multivariate correlograms. Data were collected in 1984, 1985, and 1987 on the three main shrimp grounds: Sept-Iles, North-Anticosti, and Esquiman. The LFDs were spatially autocorrelated over a wide range of scales, and well-defined homogeneous assemblages were observed in each region every year. The autocorrelation signature revealed that the spatial organization resulted from large gradients, partially related to the topography of the shrimp grounds, which probably resulted from the ontogenic depth-migration of the shrimps. The specific mean length of cohorts consistently increased along the spatial gradients, up to about one-half of the annual growth increment. This was attributed to the fact that the migration routes passed through an increasing temperature gradient, which, directly or indirectly, accelerated their growth. Significant regional and interannual differences in the relative proportion of the modal components of LFDs were noted, and were ascribed to fluctuations in the success and distribution of recruitment and survivorship.

Theoretical study of the prestressing strand's stress by computer modeling methods

2020 ◽  
Vol 76 (11) ◽  
pp. 1139-1148
Author(s):  
A. G. Korchunov ◽  
E. M. Medvedeva ◽  
E. M. Golubchik
Keyword(s):  
Residual Stresses ◽  
High Strength ◽  
Pearlitic Steel ◽  
Internal Stresses ◽  
Steel Microstructure ◽  
Compressive Stresses ◽  
Wide Range ◽  
Prestressing Strands ◽  
Increasing Temperature ◽  
Wire Strand

The modern construction industry widely uses reinforced concrete structures, where high-strength prestressing strands are used. Key parameters determining strength and relaxation resistance are a steel microstructure and internal stresses. The aim of the work was a computer research of a stage-by-stage formation of internal stresses during production of prestressing strands of structure 1х7(1+6), 12.5 mm diameter, 1770 MPa strength grade, made of pearlitic steel, as well as study of various modes of mechanical and thermal treatment (MTT) influence on their distribution. To study the effect of every strand manufacturing operation on internal stresses of its wires, the authors developed three models: stranding and reducing a 7-wire strand; straightening of a laid strand, stranding and MTT of a 7-wire strand. It was shown that absolute values of residual stresses and their distribution in a wire used for strands of a specified structure significantly influence performance properties of strands. The use of MTT makes it possible to control in a wide range a redistribution of residual stresses in steel resulting from drawing and strand laying processes. It was established that during drawing of up to 80% degree, compressive stresses of 1100-1200 MPa degree are generated in the central layers of wire. The residual stresses on the wire surface accounted for 450-500 MPa and were tension in nature. The tension within a range of 70 kN to 82 kN combined with a temperature range of 360-380°С contributes to a two-fold decrease in residual stresses both in the central and surface layers of wire. When increasing temperature up to 400°С and maintaining the tension, it is possible to achieve maximum balance of residual stresses. Stranding stresses, whose high values entail failure of lay length and geometry of the studied strand may be fully eliminated only at tension of 82 kN and temperature of 400°С. Otherwise, stranding stresses result in opening of strands.

Heritability of the Effect of Corticosteroids on Intraocular Pressure

1970 ◽  
Vol 19 (1-2) ◽  
pp. 264-267 ◽  
Author(s):  
F.H. Reuling ◽  
J.T. Schwartz
Keyword(s):  
Intraocular Pressure ◽  
Clinical Signs ◽  
Topical Steroids ◽  
Frequency Distributions ◽  
Steroid Response ◽  
Large Numbers ◽  
Wide Range ◽  
Allele Pair ◽  
High Level ◽  
Genetically Determined

In the late 1950's and early 1960's, it became evident that some glaucoma patients developed elevations of intraocular pressure, which were difficult to control, following prolonged use of systemic or ocular medications containing corticosteroids (Chandler, 1955, Alfano, 1963; Armaly, 1963). In addition, some patients without glaucoma, when treated with steroids for long periods of time, developed clinical signs of chronic simple glaucoma (McLean, 1950; François, 1954; Covell, 1958; Linner, 1959; Goldman, 1962). Fortunately, the elevation of intraocular pressure was reversible if the drug was discontinued.Over the past decade, extensive investigation of the “steroid response” has been undertaken. For this presentation, the steroid response may be considered as a gradual elevation of intraocular pressure, occurring over several weeks, in an eye being medicated with corticosteroid drops several times a day. The elevation in pressure is usually accompanied by a reduction in the facility of aqueous outflow. When relatively large numbers of subjects were tested with topical steroids, so that a wide range of responsiveness could be observed, a variation in individual sensitivity was demonstrated. Frequency distributions of intraocular pressure or change in pressure following steroids showed a skew toward the high side. On the basis of trimodal characteristics which they observed in such frequency distributions, Becker and Hahn (1964), Becker (1965) and Armaly (1965, 1966) considered the possible existence of several genetically determined subpopulations. These investigators distinguished three subpopulations on the basis of low, intermediate, and high levels of pressure response. It was hypothesized that these levels of response characterized three phenotypes, corresponding to the three possible genotypes of an allele pair, wherein one member of the pair determined a low level of response, and the other member determined a high level of response (Armaly, 1967).

scholarly journals Thermo- and Photoresponsive Behaviors of Dual-Stimuli-Responsive Organogels Consisting of Homopolymers of Coumarin-Containing Methacrylate

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 329
Author(s):  
Seidai Okada ◽  
Eriko Sato
Keyword(s):  
Functional Group ◽  
Solution Temperature ◽  
Stimuli Responsive ◽  
Critical Solution Temperature ◽  
Equilibrium Degree ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers ◽  
Dual Functional ◽  
Wide Range ◽  
Increasing Temperature

Coumarin-containing vinyl homopolymers, such as poly(7-methacryloyloxycoumarin) (P1a) and poly(7-(2′-methacryloyloxyethoxy)coumarin) (P1b), show a lower critical solution temperature (LCST) in chloroform, which can be controlled by the [2 + 2] photochemical cycloaddition of the coumarin moiety, and they are recognized as monofunctional dual-stimuli-responsive polymers. A single functional group of monofunctional dual-stimuli-responsive polymers responds to dual stimuli and can be introduced more uniformly and densely than those of dual-functional dual-stimuli-responsive polymers. In this study, considering a wide range of applications, organogels consisting of P1a and P1b, i.e., P1a-gel and P1b-gel, respectively, were synthesized, and their thermo- and photoresponsive behaviors in chloroform were investigated in detail. P1a-gel and P1b-gel in a swollen state (transparent) exhibited phase separation (turbid) through a temperature jump and reached a shrunken state (transparent), i.e., an equilibrium state, over time. Moreover, the equilibrium degree of swelling decreased non-linearly with increasing temperature. Furthermore, different thermoresponsive sites were photopatterned on the organogel through the photodimerization of the coumarin unit. The organogels consisting of homopolymers of coumarin-containing methacrylate exhibited unique thermo- and photoresponsivities and behaved as monofunctional dual-stimuli-responsive organogels.

Plasma-Assisted Combustor Dynamics Control at Ambient and Realistic Gas Turbine Conditions

2017 ◽  
Author(s):  
Wookyung Kim ◽  
Jeffrey Cohen
Keyword(s):  
Gas Turbine ◽  
Ambient Pressure ◽  
Plasma Discharge ◽  
Inlet Temperature ◽  
Pulsed Plasma ◽  
Plasma Power ◽  
Lean Blowout ◽  
Wide Range ◽  
Baseline Temperature ◽  
Increasing Temperature

The central objective of this study is to investigate the effectiveness of implementing a plasma discharge to improve combustor dynamics and flame stability. Specifically, a nano-second pulsed plasma discharge (NSPD) was applied to a premixed gaseous fuel/air dump combustor for mitigation of dynamic combustion instabilities with a minimal NOX penalty. This paper addresses the scaling of this technology from ambient pressure and temperature conditions to more realistic gas turbine combustor conditions. A model combustor operating at representative conditions of O (102) m/s flow velocity, ∼ 580 K combustor inlet temperature, and ∼ 5 atm in-combustor pressure was selected to simulate a typical low-power environment of future aero engine gas turbine combustors. Fully premixed methane or propane was utilized as a fuel. Similar to a previous ambient-pressure study, a significant reduction of pressure fluctuation level was observed, by a factor of 2X to 4X over a wide range of velocity at the baseline temperature and pressure. The plasma power required for the reduction increased linearly with increasing velocity. The change of fuel from methane to propane showed that propane requires significantly (2X) higher plasma power to achieve a similar level of noise reduction. It was also observed that the lean blowout (LBO) limit was significantly extended in the presence of the plasma, however, substantial incomplete combustion occurs in the extended regime. NOX measurements showed that the incremental NOX production due to the presence of the plasma was low (∼ < 1EINOX) in general, however, it increased with decreasing velocity and pressure, and increasing temperature.

scholarly journals Book review: The prehistoric apprentice: Investigating apprenticeship, know-how and expertise in prehistoric technologies; L’apprenti préhistorique: Appréhender l’apprentissage, les savoir-faire et l’expertise à travers les productions techniques des soci

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Manek Kolhatkar
Keyword(s):  
Material Culture ◽  
Cultural Change ◽  
Spatial Organization ◽  
Raw Material ◽  
Cultural Norms ◽  
Technological Organization ◽  
Wide Range ◽  
French And English ◽  
Culture Variability

Describing cultural change and variability and inferring sociocultural dynamics about past people and communities may be among archaeology’s main goals as a field of practice. In this regard, the concept of skill has proved its usefulness to, time and again, expand the breath of archaeologists and lithic technologists’ analyses. It covers a wide range of applications, from apprenticeship, cognition, paleo-sociology, spatial organization. It is one of the main causes for material culture variability, up there with raw material constraints, design, technological organization or cultural norms. Yet, while skill has certainly been the focus of some research in the last decades, it remains quite peripheral, when considering how central the concept should be to technological inquiries. Whatever the reasons may be, this book, edited by Laurent Klaric and fully bilingual (French and English), aims at changing that, and argues for skill to become a central concern in lithic technology. Its chapters do so strongly and the end-result is a book that should become a reference for lithic technologists, whatever their research interests or schools of thought may be.

Non-random spatial arrangement of clone sizes in chimaeric retinal pigment epithelium

Development ◽  
1986 ◽  
Vol 91 (1) ◽  
pp. 197-208
Author(s):  
Günter H. Schmidt ◽  
Maureen M. Wilkinson ◽  
Bruce A. J. Ponder
Keyword(s):  
Retinal Pigment Epithelium ◽  
Patch Size ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Spatial Arrangement ◽  
Tissue Growth ◽  
Geometric Means ◽  
Frequency Distributions ◽  
Size Frequency ◽  
Wide Range

Clonal analysis of whole-mount preparations of entire retinal pigment epithelium (RPE), using SWR ↔ C57BL/6JLac and DDK ↔ C3H/Bi mouse aggregation chimaeras in which one of the two parental components predominated, revealed a markedly non-random spatial arrangement of patch (clone) sizes. Single-cell and small patches predominated in an area around the optic nerve head while large patches occurred most frequently near the periphery. Mechanisms are discussed which may explain these results. Patch size frequency distributions were concave and skewed. Singletons were the most frequent size class, but a wide range of sizes and a smaller number of much larger patches were also always found. The results preclude the use of statistical methods previously employed to calculate clone sizes from the geometric means of observed patch sizes. Instead, the median and interquartile range may provide the best summary of the observed patch size frequency distributions. Our findings support a stochastic model of tissue growth.

Diffusion

2005 ◽  
Author(s):  
Boris S. Bokstein ◽  
Mikhail I. Mendelev ◽  
David J. Srolovitz
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Nearest Neighbor ◽  
Thermal Motion ◽  
Concentration Gradients ◽  
Entropy Of Mixing ◽  
Wide Range ◽  
P Diffusion ◽  
Phase Systems ◽  
Increasing Temperature

Diffusion is associated with the random, thermal motion of atoms that produces a change in the macroscopic concentration profile. This process occurs in gases, liquids, amorphous and crystalline solids of metals, ceramics, polymers, semiconductors, etc. The investigation of diffusion provides valuable information about the atomic structure of materials and the defects within them. Perhaps, most importantly, diffusion controls the rates of a wide range of kinetic processes associated with the synthesis of materials, processes by which we modify materials, and processes by which materials fail. The most common driving force for diffusion in a single-phase systems is associated with the entropy of mixing of its constituents (recall that we showed that the entropy of mixing of gases and the components of an ideal solution are always positive—see Sections 1.2.6 and 3.3). Since diffusional processes occur through the thermal motion of atoms (see below), it will not be surprising to learn that the rate of diffusion increases with increasing temperature. However, note that while the mechanisms of thermal motion in gases (random collision of atoms with each other) and liquids (e.g. Brownian motion) necessarily lead to mixing, the mechanisms of mixing within a solid are not as obvious. In solids, thermal motion corresponds to the vibrations of atoms near their equilibrium positions. Since the amplitude of such vibrations is much smaller than the nearest-neighbor separation, it would seem that such thermal motions cannot lead to mixing. Thus, the question ‘‘how do atoms migrate in solids’’ is not so simple. The equations describing diffusion were suggested by the physiologist Fick in 1855 as a generalization of the equations for heat transfer suggested by Fourier in 1824. Fick’s equations for diffusion can be obtained by analogy with Fourier’s equations for heat transfer by replacing heat with the number of atoms, temperature with concentration, and thermal conductivity with diffusivity. Fick’s first law provides a relationship between atomic currents and concentration gradients. As discussed above, this relationship can be understood by analogy with thermal conductivity or electrical conductivity.

scholarly journals A Colorimetric Method for Studying the Dissociation of Oxyhæmocyanin suitable for Class Work

1925 ◽  
Vol 13 (4) ◽  
pp. 970-980 ◽  
Author(s):  
C. F. A. Pantin ◽  
Lancelot T. Hogben
Keyword(s):  
Marked Effect ◽  
Colorimetric Method ◽  
Hydrogen Ion ◽  
Ion Concentration ◽  
Dissociation Curve ◽  
Hydrogen Ion Concentration ◽  
Laboratory Class ◽  
Wide Range ◽  
Increasing Temperature ◽  
Limits Of Error

1. A simple colorimetric method for plotting the dissociation curve of haemocyanin is indicated. The limits of error are within 5 per cent. The simplicity of the method commends it for laboratory class work.2. The effect of hydrogen ion concentration on the dissociation of the hsemocyanins of the crustacean Palinurus and the pulmonate Helix have been compared. In the snail change of hydrogen ion concentration over a wide range was not found to affect the dissociation of the hsemocyanin: in 'the crustacean there is a marked effect similar to that seen in the dissociation of hæmoglobin.3. The similarity of crustacean hsemocyanin to haemoglobin is also seen in that increasing temperature depresses the dissociation curve. The effects of certain salts upon haemocyanin. have also been recorded.

Über die pH- und Temperatur-Abhängigkeit des thermischen Zerfalls von Poliovirus-Teilchen in Nucleinsäure und leere Proteinhüllen

1966 ◽  
Vol 21 (4) ◽  
pp. 357-361 ◽  
Author(s):  
O. Drees ◽  
K. D. Demme
Keyword(s):  
Heat Treatment ◽  
Initial Rate ◽  
Concentrated Suspensions ◽  
Virus Particles ◽  
Ph Values ◽  
Intact Virus ◽  
Wide Range ◽  
Ultracentrifugal Analysis ◽  
Increasing Temperature ◽  
Kinetics Of

The intact virus particles of highly purified, concentrated suspensions of poliovirus have been disintegrated into free nucleic acid and empty protein shells (78 S protein) by moderate heat treatment at various temperatures and pH values. The kinetics of this degradation has been followed by ultracentrifugal analysis.With increasing temperature between 35° and 50 °C and with increasing pH of the suspension medium between 7 and 8, the rate of degradation increased. For any particular conditions the initial rate was not maintained, and after a certain time there was little further degradation if conditions remained unaltered. Some particles with the sedimentation characteristics of poliovirus were resistant to disintegration under the same conditions which led to the breakdown of the bulk of the virus. The proportion of this “stable fraction” varied within a wide range from one preparation to another and decreased with increasing temperature and with increasing pʜ.

Modelling casein aggregation and curd firming in goats' milk from backscatter of infrared light

2003 ◽  
Vol 70 (3) ◽  
pp. 335-348 ◽  
Author(s):  
Manuel Z Castillo ◽  
Fred A Payne ◽  
Clair L Hicks ◽  
José S Laencina ◽  
María-Belén M López
Keyword(s):  
Kinetic Model ◽  
Diffuse Reflectance ◽  
Block Design ◽  
Reaction Model ◽  
Order Reaction ◽  
Infrared Light ◽  
Wide Range ◽  
Data Points ◽  
Increasing Temperature ◽  
Reflectance Ratio

A kinetic model was proposed for describing the curd assembly of skimmed goats' milk during enzymic coagulation. The enzymic coagulation of milk was monitored using an optical sensor that measured diffuse reflectance (light backscatter) at 880 nm. The appearance of a shoulder, at low temperatures and protein concentrations, in the diffuse reflectance ratio profile after the inflection point of the curve (Tmax) appeared to separate the aggregation and curd firming steps. The diffuse reflectance ratio profile after Tmax was attributed to the overlapping of casein micelles aggregation and curd firming reactions. The developed kinetic model combined a second order reaction model to describe aggregation reactions and a first order reaction model to describe firming processes reactions. A completely randomised block design with three replications was used to determine the effect of protein concentration and temperature on kinetic constants. Milk was adjusted to three levels of protein (30, 50 and 70 g/kg), and coagulated at five temperatures (20, 25, 30, 35 and 40°C) to test a wide range of processing conditions. Data points from each profile after Tmax were fitted to the proposed model using non-linear regression. The average R2 and standard error of prediction (SEP) for 45 tests conducted were in the range of 0·9975±0·0027 and 0·0081±0·0037, respectively. A significant increase in characteristic times for aggregation (τ2) and curd firming processes (τ1) were found when temperature decreased or protein increased. Theoretical asymptotic value of reflectance ratio, R∞, increased with increasing level of protein and temperature (P<0·05). The parameter β1, which represented the fraction of diffuse reflectance ratio attributed to aggregation, decreased with increasing temperature and decreasing protein.

Sign in / Sign up

Export Citation Format

Share Document