Molecular Theory of Energy Conversion and of Initiation of Chemical Reactions in Solids

1971 ◽  
Vol 49 (9) ◽  
pp. 1407-1412
Author(s):  
Charles E. Melton
Keyword(s):  
Energy Conversion ◽  
Chemical Reactions ◽  
Present Model ◽  
Nearest Neighbor ◽  
Vibrational Energy ◽  
Vibrational Excitation ◽  
Hard Sphere Model ◽  
Mean Velocity ◽  
The Mean ◽  
The Individual

A theory has been developed to describe the initiation of chemical reactions in solids. Two basic assumptions are made to formulate the model. First, the initiation of chemical reactions in solids ultimately results from the vibrational excitation of the individual molecules in the solid, and second, the lattice vibrations in a solid can be treated as pseudocollisions between the individual molecules in the lattice. In effect, the solid is treated as an ordered dense gas. These assumptions permit us to describe chemical reactions in a solid within the framework of collision theory. The resultant rate constant, k, depends on molecular and lattice parameters and on the temperature. It is of the form [Formula: see text], where N is the number of nearest neighbor molecules, b is the lattice spacing, v is the mean velocity of the individual molecules, and [Formula: see text]is the probability of translational–vibrational energy conversion.Conclusions based on the present model are in accord with qualitative results from a hard sphere model. For example, energy conversion (translational to vibrational) is many orders of magnitude greater in the region of a defect. Consequently, the probability for initiation of chemical reactions is orders of magnitude greater in the region of a defect.

scholarly journals Doppler Shift of Radio Signals Transmitted between Orbiting Satellites

1982 ◽  
Vol 35 (2) ◽  
pp. 155 ◽  
Author(s):  
PL Dyson ◽  
JA Bennett
Keyword(s):  
Electron Concentration ◽  
Doppler Shift ◽  
Rate Of Change ◽  
Line Of Sight ◽  
Concentration Gradients ◽  
Mean Velocity ◽  
Radio Signals ◽  
The Mean ◽  
The Moment ◽  
The Individual

A general expression, applicable at VHF and above, is derived for the Doppler shift of radio signals transmitted between two satellites embedded in the ionosphere. The Doppler shift is made up of several contributions which depend on (a) the rate of change of the free space path between the satellites, (b) the components, perpendicular to the line of sight between the satellites, of both the mean velocity of the satellites and the electron concentration gradients, (c) the moment of the perpendicular electron concentration gradients and the deviations from the mean of the individual satellite perpendicular velocities, (d) the velocity components along the line of sight between the satellites, and the electron concentration values at each satellite, and (e) changes occurring in the ionosphere with time.

Growth, Metamorphosis and Energy Conversion in the Larvae of the Prawn, Palaemon Serratus

1969 ◽  
Vol 49 (1) ◽  
pp. 77-96 ◽  
Author(s):  
M. R. Reeve
Keyword(s):  
Energy Conversion ◽  
Larval Growth ◽  
Energy Conversion Efficiency ◽  
Variable Number ◽  
Larval Stages ◽  
Length Increase ◽  
History Of ◽  
The Mean ◽  
The Individual ◽  
Very High

The life-history of the larva of the prawn Palaemon serratus (Pennant) was studied in the laboratory and found to comprise a variable number of stages, dependent on feeding level and other factors. Larval moulting frequency was relatively constant at 3-day intervals, and could be followed in a population by daily examination for exuvia moult-casts. Length increase at each moult progressed arithmetically, and the highest mortalities occurred during metamorphosis. Consumption of Anemia nauplii by each larva rose from 30 to 400 per day. Populations of isolated animals (i.e. when cannibalism was excluded) were inspected daily and the exact number and duration of larval stages determined. Survival through metamorphosis was very high (over 85%) at both high and low feeding levels, although at the latter the larvae passed through more stages with more erratic duration times. At the end of the experiment, when all the larvae had metamorphosed, the mean dry weights at the high and low feeding levels were 7.7 and o.6 mg respectively. Larval stages could not be positively identified morphologically after stage III unless the history of the individual in question was known. It is suggested that the number of larval stages in the sea may also be very variable and difficult to determine.Energy-conversion efficiency was calculated from food uptake measurements and larval growth estimations, and was found to be 50–60% during most of the larval life, falling to 35% when the early post-larvae were taken into account.

Turbulence Modeling for the Axially Rotating Pipe From the Viewpoint of Analytical Closures

2003 ◽  
Author(s):  
Robert Rubinstein ◽  
Ye Zhou
Keyword(s):  
Eddy Viscosity ◽  
Present Model ◽  
Turbulence Modeling ◽  
Single Point ◽  
Mean Velocity ◽  
Eddy Viscosity Model ◽  
Rotating Turbulence ◽  
The Mean ◽  
Production Mechanisms ◽  
Rapid Pressure

A single-point model eddy viscosity model of rotation effects on the turbulent flow in an axially rotating pipe is developed based on two-point closure theories. Rotation is known to impede energy transfer in turbulence; this fact is reflected in the present model through a reduced eddy viscosity, leading to laminarization of the mean velocity profile and return to a laminar friction law in the rapid rotation limit. This model is compared with other proposals including linear redistribution effects through the rapid pressure-strain correlation, Richardson number modification of the eddy viscosity in a model of non-rotating turbulence, and the reduction of turbulence through the suppression of near-wall production mechanisms.

Measurement of feature clustering in images

1990 ◽  
Vol 48 (1) ◽  
pp. 552-553
Author(s):  
John C. Russ
Keyword(s):  
Spatial Distribution ◽  
Random Distribution ◽  
Nearest Neighbor ◽  
Mean Value ◽  
Feature Clustering ◽  
Spatial Coordinates ◽  
Distribution Of Points ◽  
The Mean ◽  
The Individual ◽  
Nearest Neighbor Distances

The spatial distribution of features in an image is often interesting, but not simple to characterize. Mapping of the image into a different space (e.g., Fourier or Hough) offers direct information on various regularities in feature spacing or alignment, but does not deal directly with the individual features. Two other approaches are available; each has advantages and drawbacks, which are discussed here.Schwarz & Exner determine the spatial coordinates of the centroids of features, and sort them to locate the nearest neighbor for each feature present, constructing a distribution plot of the frequency of nearest neighbor distances. Figures 1 and 2 show an example. The three fields in Figure 1 contain, respectively, features which are well-spaced from each other, randomly arranged on the plane, and clustered together. For the random distribution of points, the histogram of nearest neighbor distances is a Poisson distribution, and the mean value is 0.5/NA1/2, where NA is the number of features divided by the area of the image.

The mean velocity and velocity distributions of normal bull spermatozoa at different hydrogen-ion concentrations, derived from photo-electric measurements

1960 ◽  
Vol 54 (3) ◽  
pp. 300-309 ◽  
Author(s):  
C. van Duijn ◽  
R. Rikmenspoel
Keyword(s):  
Frequency Distribution ◽  
Ph Value ◽  
Strain Effect ◽  
Anaerobic Conditions ◽  
Mean Velocity ◽  
Ph Values ◽  
The Mean ◽  
The Individual ◽  
Image Position ◽  
Ph Curve

1. The mean velocity ῡ and the velocity frequency distribution f(υ) of bull spermatozoa with normal motility have been determined in standardized eggyolk—citrate buffers at different pH values, ranging frompH 5·70 to 8·35.Under assumed approximately anaerobic conditions at37·0 ± 0·1° C. the mean velocity was found to show a straight-line relationship -with pH in the physiological region pH 5·70–7·50, according to the general equationStatistically, k was shown to be a linear function of a, namely,Consequently, the dependence of the mean velocity of the spermatozoa from any ejaculate can be characterized by the one parameter a = dῡ/dpH. (dimension μ/sec./pH), determining the slope of the ῡ υs. pH curve.The mean velocity of all individual spermatozoa (measurements of all ejaculates at the same pH value pooled together) could be described accurately by the equation:For some ejaculates the linear relationship was found to hold up to pH 8·00.2. The velocity frequency distribution curves were found to change with pH. At pH 5·70 the curves are skew with a relatively high top value. At increasing pH values both the top value and skewness decrease. The mean standard deviation of the velocity distribution f(υ) was found to be proportional to pH and could be described by the equationThis means that the variability in swimming speeds of the individual spermatozoa of any ejaculate increases proportionally with pH, indicating a strain effect of increasing alkalinity on the population, irrespective of the general stimulation of motility in the region up to pH 7·50.3. At each pH value the mean velocity decreases with time. Under assumed approximately anaerobic conditions at 37° C. the speed of velocity decrease as a function of pH was found to differ so much between different ejaculates that no generalization could be derived from the available material. The same holds for the effect of pH on the number of normally moving spermatozoa in the diluted ejaculate.4. The total number of spermatozoa moving normally depends on pH, but the optimum varies with the individual ejaculates.

Influence of Grip Width and Anthropometric Characteristics on the Bench-Press Load–Velocity Relationship

2020 ◽  
Vol 15 (7) ◽  
pp. 949-957
Author(s):  
Alejandro Pérez-Castilla ◽  
Daniel Jerez-Mayorga ◽  
Dario Martínez-García ◽  
Ángela Rodríguez-Perea ◽  
Luis J. Chirosa-Ríos ◽  
...  
Keyword(s):  
Linear Regression ◽  
Multiple Linear Regression ◽  
Regression Models ◽  
Bench Press ◽  
Linear Regression Models ◽  
Mean Velocity ◽  
Movement Velocity ◽  
Anthropometric Characteristics ◽  
The Mean ◽  
The Individual

Purpose: To compare the load–velocity (L-V) relationship between bench-press exercises performed using 4 different grip widths, to determine the association between the anthropometric characteristics and L-V profile, and to explore whether a multiple linear-regression model with movement velocity and subjects’ anthropometric characteristics as predictor variables could increase the goodness of fit of the individualized L-V relationship. Methods: The individual L-V relationship of 20 men was evaluated by means of an incremental loading test during the bench-press exercise performed on a Smith machine using narrow, medium, wide, and self-selected grip widths. Simple and multiple linear-regression models were performed. Results: The mean velocity associated with each relative load did not differ among the 4 grip widths (P ≥ .130). Only body height and total arm length were correlated with the mean velocity associated with light and medium loads (r ≥ .464). A slightly higher variance of the velocity attained at each relative load was explained when some anthropometric characteristics were used as predictor variables along with the movement velocity (r2 = .969 [.965–.973]) in comparison with the movement velocity alone (r2 = .966 [.955–.968]). However, the amount of variance explained by the individual L-V relationships was always higher than with the multiple linear-regression models (r2 = .995 [.985–1.000]). Conclusions: These results indicate that the individual determination of the L-V relationship using a self-selected grip width could be recommended to monitor relative loads in the Smith machine bench-press exercise.

A Simple Method for the Evaluation of Internal Doses in Nuclear Medicine

1974 ◽  
Vol 13 (02) ◽  
pp. 193-206
Author(s):  
L. Conte ◽  
L. Mombelli ◽  
A. Vanoli
Keyword(s):  
Nuclear Medicine ◽  
Close Agreement ◽  
Whole Body ◽  
Simple Method ◽  
Rapid Estimation ◽  
Absorbed Doses ◽  
The Mean ◽  
The Individual ◽  
Estimation Of Risk

SummaryWe have put forward a method to be used in the field of nuclear medicine, for calculating internally absorbed doses in patients. The simplicity and flexibility of this method allow one to make a rapid estimation of risk both to the individual and to the population. In order to calculate the absorbed doses we based our procedure on the concept of the mean absorbed fraction, taking into account anatomical and functional variability which is highly important in the calculation of internal doses in children. With this aim in mind we prepared tables which take into consideration anatomical differences and which permit the calculation of the mean absorbed doses in the whole body, in the organs accumulating radioactivity, in the gonads and in the marrow; all this for those radionuclides most widely used in nuclear medicine. By comparing our results with dose obtained from the use of M.I.R.D.'s method it can be seen that when the errors inherent in these types of calculation are taken into account, the results of both methods are in close agreement.

SERUM THYROTROPHIN AND THE RESPONSE TO THYROTROPHIN RELEASING HORMONE IN SYMPTOMLESS AUTOIMMUNE THYROIDITIS AND IN BORDERLINE AND OVERT HYPOTHYROIDISM

1974 ◽  
Vol 75 (2) ◽  
pp. 274-285 ◽  
Author(s):  
A. Gordin ◽  
P. Saarinen ◽  
R. Pelkonen ◽  
B.-A. Lamberg
Keyword(s):  
Autoimmune Thyroiditis ◽  
Elevated Serum ◽  
Mean Value ◽  
Primary Hypothyroidism ◽  
Overt Hypothyroidism ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
The Mean ◽  
The Individual ◽  
Serum Tsh

ABSTRACT Serum thyrotrophin (TSH) was determined by the double-antibody radioimmunoassay in 58 patients with primary hypothyroidism and was found to be elevated in all but 2 patients, one of whom had overt and one clinically borderline hypothyroidism. Six (29%) out of 21 subjects with symptomless autoimmune thyroiditis (SAT) had an elevated serum TSH level. There was little correlation between the severity of the disease and the serum TSH values in individual cases. However, the mean serum TSH value in overt hypothyroidism (93.4 μU/ml) was significantly higher than the mean value both in clinically borderline hypothyroidism (34.4 μU/ml) and in SAT (8.8 μU/ml). The response to the thyrotrophin-releasing hormone (TRH) was increased in all 39 patients with overt or borderline hypothyroidism and in 9 (43 %) of the 21 subjects with SAT. The individual TRH response in these two groups showed a marked overlap, but the mean response was significantly higher in overt (149.5 μU/ml) or clinically borderline hypothyroidism (99.9 μU/ml) than in SAT (35.3 μU/ml). Thus a normal basal TSH level in connection with a normal response to TRH excludes primary hypothyroidism, but nevertheless not all patients with elevated TSH values or increased responses to TRH are clinically hypothyroid.

The flow of liquid in a stream from the standard turbine impeller

1979 ◽  
Vol 44 (3) ◽  
pp. 700-710 ◽  
Author(s):  
Ivan Fořt ◽  
Hans-Otto Möckel ◽  
Jan Drbohlav ◽  
Miroslav Hrach
Keyword(s):  
Reynolds Number ◽  
Kinematic Viscosity ◽  
Momentum Flux ◽  
Relative Size ◽  
Mean Velocity ◽  
Axial Profile ◽  
The Mean ◽  
Hot Film ◽  
Turbine Impeller

Profiles of the mean velocity have been analyzed in the stream streaking from the region of rotating standard six-blade disc turbine impeller. The profiles were obtained experimentally using a hot film thermoanemometer probe. The results of the analysis is the determination of the effect of relative size of the impeller and vessel and the kinematic viscosity of the charge on three parameters of the axial profile of the mean velocity in the examined stream. No significant change of the parameter of width of the examined stream and the momentum flux in the stream has been found in the range of parameters d/D ##m <0.25; 0.50> and the Reynolds number for mixing ReM ##m <2.90 . 101; 1 . 105>. However, a significant influence has been found of ReM (at negligible effect of d/D) on the size of the hypothetical source of motion - the radius of the tangential cylindrical jet - a. The proposed phenomenological model of the turbulent stream in region of turbine impeller has been found adequate for values of ReM exceeding 1.0 . 103.

scholarly journals The Reaction of Spin–Orbit State-Selected Ca(PJ03) With CH3I, CH2I2, and SF6

1986 ◽  
Vol 6 (6) ◽  
pp. 391-402 ◽  
Author(s):  
Mark L. Campbell ◽  
Nick Furio ◽  
Paul J. Dagdigian
Keyword(s):  
Chemical Reactions ◽  
Cross Sections ◽  
Optical Pumping ◽  
Spin Orbit ◽  
Alkyl Bromide ◽  
The Individual ◽  
State Selection

Chemiluminescence cross sections for reaction of the individual spin–orbit states of metastable Ca(PJ03) with CH3I, CH2I2, and SF6 have been determined by the use of optical pumping state selection. This technique was also used to separate the chemiluminescence arising from the two excited metastable Ca 3P0 and 1D states. The spin–orbit dependence of the chemiluminescence pathway was found to be substantial for the CH3I and CH2I2 reactions and similar to that previously observed for halogen diatom and alkyl bromide reagents. By contrast, no spin–orbit effect was observed for Ca(3P0)+SF6. These results are discussed in terms of our previously presented model for the origin of spin–orbit effects in chemical reactions.

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