scholarly journals The average energy of disintegration of radium E

1927 ◽  
Vol 117 (776) ◽  
pp. 109-123 ◽  
Keyword(s):  
Average Energy ◽  
The Body ◽  
Secondary Process ◽  
Characteristic Energy ◽  
Γ Radiation ◽  
Wide Range ◽  
Continuous Energy Spectrum ◽  
The Mean ◽  
High Degree ◽  
Α Particles

The problem of the velocity of the particles emitted from the nuclei of dis integrating radioactive atoms has always attracted considerable attention. It was early established that in the case of the α-rays all the particles from one substance were emitted with the same velocity, and the latest experiments of Briggs have emphasised the high degree of homogeneity attained. This result, showing that each disintegration involves exactly the same emission of energy, is easily reconcilable with our general ideas of the radioactive processes, and, as is well known, there is undoubtedly some connection between this characteristic energy and the mean life of the body. The behaviour of the β-ray bodies is in sharp contrast to this. In place of the α-particles all emitted with the same energy, we find that the disintegration electrons coming from the nucleus have energies distributed over a wide range. For example, in the case of radium E this continuous energy spectrum formed by the disintegration electrons has an upper limit at 1,050,000 volts, rises to a maximum at 300,000 volts, and continues certainly as low as 40,000 volts, and similar results have been obtained for other β-ray bodies. If this result is interpreted as showing that different disintegrating nuclei of the same substance emit their disintegration electron with different energies, we must deduce that in this case the energy of disintegration is not a characteristic constant of the body, but can vary between wide limits. Many workers have considered this to be so contrary both to the ideas of the quantum theory and the definiteness shown by radioactive disintegration that they have asserted the inhomogeneity must be a result of some secondary process, such as collision with the extranuclear electrons or emission of general γ-radiation, and that although we cannot observe them before they become inhomogeneous, the disintegration electrons are actually emitted from the nucleus with a definite characteristic energy as in the case of the α-particles.

scholarly journals Large elastic deformations of isotropic materials. I. Fundamental concepts

1948 ◽  
Vol 240 (822) ◽  
pp. 459-490 ◽  
Keyword(s):  
The Body ◽  
Elastic Behaviour ◽  
Stress And Strain ◽  
Elastic Deformations ◽  
Hooke’S Law ◽  
Widespread Agreement ◽  
Wide Range ◽  
Hooke's Law ◽  
High Degree

The mathematical theory of small elastic deformations has been developed to a high degree of sophistication on certain fundamental assumptions regarding the stress-strain relationships which are obeyed by the materials considered. The relationships taken are, in effect, a generalization of Hooke’s law— ut tensio, sic vis . The justification for these assumptions lies in the widespread agreement of experiment with the predictions of the theory and in the interpretation of the elastic behaviour of the materials in terms of their known structure. The same factors have contributed to our appreciation of the limitations of these assumptions. The principal problems, which the theory seeks to solve, are the determination of the deformation which a body undergoes and the distribution of stresses in it, when certain forces are applied to it, and when certain points of the body are subjected to specified displacements. These problems are always dealt with on the assumption that the generalization of Hooke’s law is obeyed by the material of the body and that the deformation is small, i.e. the change of length, in any linear element in the material, is small compared with the length of the element in the undeformed state. Apart from the fact that the generalization of Hooke’s law is obeyed accurately by a very wide range of materials, under a considerable variety of stress and strain conditions, it has the further advantage that it leads to a mathematically tractable theory.

scholarly journals The ranges of the α-particles from the radioactive emanations and “A” products and from polonium

1932 ◽  
Vol 136 (829) ◽  
pp. 349-363 ◽  
Keyword(s):  
Long Range ◽  
Point Of View ◽  
Counting Methods ◽  
Γ Rays ◽  
The Mean ◽  
High Degree ◽  
Α Particles

The analysis of groups of α-particles by new counting methods has been described in previous papers, in which details have been given of the examination of the α-particles emitted by radium-C and -C' thorium-C and -C', and actinium-C and -C', including the long range particles. The methods have the advantage that any appreciable inhomogeneity of a group of α-particles is readily detected, and moreover, the mean range of a group may be directly measured with a high degree of precision. The experiments have now been extended to an examination of the α-particles emitted by the emanations and “A” products of the three radioactive series, and by polonium. The examination of these α-ray groups is not only of great interest from the point of view of the radioactive transformations, but also for the possible connection with the emission of γ-rays.

scholarly journals An Evaluation of the Potential of Heparin to Inhibit the Viral Entry of SARS-CoV-2

2021 ◽  
Keyword(s):  
Viral Entry ◽  
The Body ◽  
Ligand Docking ◽  
Binding Potential ◽  
Docking Simulations ◽  
Binding Domains ◽  
Wide Range ◽  
Novel Coronavirus ◽  
Viral Components ◽  
High Degree

Heparin is an anticoagulant medicine that prevents the formation of harmful blood clots in the vessels. Following the outbreak of the novel coronavirus disease 2019 (COVID-19), heparin has helped to improve the health of affected patients beyond its anticoagulant effects. The potential antiviral activity of heparin has attracted speculation due to its highly sulfated profile, which allows it to have a high binding affinity to a wide range of viral components. Heparin’s successful binding to the ZIKA virus, human immunodeficiency virus, as well as the SARS CoV and MERS CoV spike proteins have demonstrated its potential to inhibit the entry of SARS-CoV-2 into the body. A high degree of sequence homology also enables heparin to have inhibitory binding potential on viral components. The SARS-CoV-2 virus exhibits significant differences in its spike glycoprotein (SGP) sequence compared to other coronaviruses. The SGP sequence in SARS-CoV-2 contains additional potential glycosaminoglycan (GAG) binding domains that may drive differences in the attachment and entry process of the virus. Findings from unbiased computational ligand docking simulations, pseudotyped spike protein experiments, and cell to cell fusion assays have also opened possibilities to investigate the antiviral properties of heparin in clinical trials

scholarly journals The role of MRI in comparison between benign and malignant chest wall masses in correlation with pathology

2021 ◽  
Vol 52 (1) ◽  
Author(s):  
Marian Fayek Farid Kolta ◽  
Nessma Kamal Abd El Rheem ◽  
Amr Farouk Ibrahim ◽  
Mohammed Raafat Abd El-Mageed
Keyword(s):  
Soft Tissue ◽  
Chest Wall ◽  
The Body ◽  
Benign Tumors ◽  
Main Body ◽  
Primary Tumors ◽  
Wide Range ◽  
Significant Difference ◽  
Adc Values ◽  
The Mean

Abstract Background Tumors that arise from the chest wall (including bone structures such as the sternum, clavicle, scapula, and ribs) or from adjacent soft tissues are less common than other parts of the body, and so the resulting unfamiliarity can make it difficult to limit the number of possible diagnoses. These tumors have a wide range of possibilities, including primary chest wall tumors arising from the bone or soft tissue, which are subdivided into malignant and benign tumors, and the secondary metastatic deposits. The aim of the study is to investigate the ability of MRI with diffusion sequence in differentiation between benign and malignant chest wall masses, which is subsequently reflected in the management of chest wall masses patients. Main body MRI has superior soft-tissue resolution and value for local assessment of primary tumors and accurate tissue characterization and plays a key role in preoperative staging to assess for multi-spatial and multi-compartment involvement. ADC values were obtained in 31 patients, and the mean ADC values of benign (13 patients) chest wall masses were 1.31 ± 0.50 × 10−3 mm2/s while the mean ADC values of the malignant (18 patients) chest wall masses were 0.98 ± 0.36 × 10−3 mm2/s. There was a statistically significant difference between the ADC values obtained from the malignant and benign chest wall masses (P < 0.001). Conclusion This study demonstrates that diffusion-weighted MR imaging is a growing imaging modality to predict the histopathological differentiation of malignant from benign chest wall masses.

scholarly journals A redetermination of the velocities of α particles from radium C, thorium C and C'

1928 ◽  
Vol 118 (780) ◽  
pp. 549-557 ◽  
Keyword(s):  
Electric Fields ◽  
Experimental Error ◽  
Atomic Weight ◽  
Mean Value ◽  
Experimental Result ◽  
Slow Moving ◽  
The Mean ◽  
High Degree ◽  
Active Substances ◽  
Α Particles

1. The first accurate determinations of the velocity with which an α particle is expelled from a radio-active substance and of the value of E/M, the ratio of the charge to the mass, were made by Rutherford and Robinson by measuring the deflections in magnetic and electric fields. An α particle moving with velocity V perpendicular to the direction of a magnetic field H describes a circle of radius ρ where H ρ = MV/E. Rutherford and Robinson found for α particles expelled from radium C Hρ = 3·983 X 10 5 E. M. U. and V = 1·922 X 10 9 cm. per second. The mean value of E/M for α particles from radium emanation, radium A and radium C was 4820 E. M. U., which agreed to within the limits of experimental error with the value 4826 deduced from electrochemical data taking the atomic weight of helium as 3·998 and the value of the faraday as 9647. This value of the velocity of α particles from radium C has served as a standard from which the velocities of α particles from other radio-active substances have been calculated from the Geiger relation V 3 = k R. The present paper gives an account of a redetermination of the quantity Hρ for α particles from radium C by a method which is essentially similar to those used in previous determinations of this kind. From the value of Hρ the velocity has been calculated using the theoretical value of E/M which can be found to a high degree of accuracy from more recent determinations of the atomic weight of helium and the value of the faraday, taking into account the relativity correction for the increase in mass of the α particle. For the atomic weight of helium we may take 4·000, the value deduced by Van Laar from a consideration of the density determinations of Watson, Heuse, Taylor, and in particular of Guye’s discussion of Taylor’s results. Taking the value of the faraday given by recent determinations 9649·4 E. M. U. the value of E/M for a slow moving α particle is 4824·7 and on applying the correction for the relativity change of mass this becomes 4814·8 for the α particle from radium C, neglecting the mass of the lost electrons. It may be noted that Rutherford and Robinson’s experimental result, 4820 agrees as well with this latter value as with the value 4826 which they calculated.

scholarly journals Valve methods of recording single alpha-particles in the presence of powerful ionising radiations

1931 ◽  
Vol 131 (817) ◽  
pp. 391-409 ◽  
Keyword(s):  
Solid Angle ◽  
Alpha Particles ◽  
Original Form ◽  
Γ Radiation ◽  
Simple Matter ◽  
The Mean ◽  
Ionising Radiations ◽  
Large Groups ◽  
Α Particles ◽  
Number Of Particles

In 1926, Greinacher showed that it was possible to detect single α-particles by linearly amplifying the ionisation current due to an α-ray by means of thermionic valves. Subsequently, he was also able to detect single H-particles by the same method. Other workers have since applied the method to various radio-active problems in which the counting would otherwise have had to be done by means of scintillation screens or Geiger counters, etc. The present writers, working in conjunction with H. M. Cave, also employed the method for determining the mean rate of emission of α-particles from radium C, by counting accurately the number of particles emitted within a defined solid angle. While the problem of encounting α- or H-particles can be a comparatively simple matter under certain conditions, there are many experiments necessarily carried out under conditions which render it utterly impossible to employ the Greinacher method in its original form. These experiments involve the counting of comparatively few particles in the presence of disturbances caused by powerful β- or γ- radiation, or by large groups of α-particles which it is not desired to count.

scholarly journals Fatness and thermoregulation of qualified rugby players

2019 ◽  
Vol 68 ◽  
pp. 02011
Author(s):  
Inese Pontaga ◽  
Jekaterina Liepina ◽  
Dzintra Kazoka ◽  
Silvija Umbrasko
Keyword(s):  
Body Mass ◽  
Body Fat ◽  
Large Body ◽  
The Body ◽  
Body Fat Percentage ◽  
Fat Percentage ◽  
Wide Range ◽  
The Mean ◽  
Body Fat Percent ◽  
Rugby Players

A large body size and mass are advantages in rugby. The desire to gain weight can bring players to become overweight or obese. This can worsen their thermoregulation and health risks. The aim was to evaluate anthropometric characteristics and to determine the effect of additional body fat percentage on sweat loss during play-match in male rugby players. Nineteen qualified male rugby players were tested during play-match. The age, height, body mass, body mass index (BMI) and body fat percent of participants were: 29 ± 6 years, 183 ± 7 cm, 96.86 ± 12.88 kg, 29.07 ± 3.90 kg/m2, 20.52 ± 5.64%, respectively. The skin fold thickness measurement was used to assess body fat percent. Body mass loss was detected by weighting. The mean BMI was 26.18 ± 2.37 (kg/m2) and the body fat 15.87 ± 3.97% in backs. Forwards were significantly heavier and had BMI 31.18 ± 3.44 (kg/m2)(p = 0.002) and the body fat 23.91 ± 4.02% (p < 0.001). The mean body mass decrease in the play-match was 1.83 ± 0.84%. The mean sweating intensity was 2.24 ± 1.07 l/h, but individual varied among players in very wide range (1.12–6.16 l/h). Relationships between the body fat percentage and sweating intensity was not determined (p > 0.05). Recommendation is to increase the volume of regular strength training, to correct the diet and liquid consumption.

scholarly journals The analysis of adaptation in a plant-breeding programme

1963 ◽  
Vol 14 (6) ◽  
pp. 742 ◽  
Author(s):  
KW Finlay ◽  
GN Wilkinson
Keyword(s):  
Regression Coefficient ◽  
Morphological Characteristics ◽  
South Australia ◽  
Plant Introduction ◽  
Similar Degree ◽  
Logarithmic Scale ◽  
World Collection ◽  
Wide Range ◽  
The Mean ◽  
High Degree

The adaptation of barley varieties was studied by the use of grain yields of a randomly chosen group of 277 varieties from a world collection, grown in replicated trials for several seasons at three sites in South Australia. For each variety a linear regression of yield on the mean yield of all varieties for each site and season was computed to measure variety adaptation. In these calculations the basic yields were measured on a logarithmic scale, as it was found that a high degree of linearity was thereby induced. The mean yield of all varieties for each site and season provided a quantitative grading of the environments; and from the analysis described, varieties specifically adapted to good or poor seasons and those showing general adaptability may be identified. The study of the adaptation of the whole population of varieties was facilitated by the use of a two-dimensional plot (scatter diagram), with mean yield and regression coefficient as coordinates for each variety. Though wide variation was evident in both mean yield and sensitivity to environment as characterized by the regression coefficient, the variation in sensitivity was proportionately less among varieties with higher mean yield, and the varieties with highest mean yield exhibited, within very narrow limits (regression coefficients close to 0.8), a similar degree of adaptation to all environments over the wide range, especially of seasonal conditions, typical of the South Australian cereal belt. Varieties from particular geographic regions of the world showed a similarity in type of adaptation, which provides a useful basis for plant introduction. Phenotypic stability and physiological and morphological characteristics of groups of varieties with specific or general adaptability are discussed in relation to plant introduction and breeding.

Motoneurone Discharges to the Eyecup Muscles of the Crab carcinus

1968 ◽  
Vol 49 (2) ◽  
pp. 251-267
Author(s):  
M. BURROWS ◽  
G. A. HORRIDGE
Keyword(s):  
The Body ◽  
Muscle Fibres ◽  
Tonic Activity ◽  
Large Scatter ◽  
Absolute Position ◽  
Wide Range ◽  
Long Time ◽  
Slow Muscle Fibres ◽  
The Mean ◽  
The Right

1. During imposed tilt the eyecup or the crab tends to preserve an absolute position which depends upon the tonic activity of eight of the nine eyecup muscles. The detailed activity of all these muscles during imposed tilt in different planes has been recorded intracellularly. 2. The slow- and fast-motoneurone discharges to the eyecup muscles differ in that the former have intervals which are more variable at lower frequencies but the latter are more variable at higher frequencies. 3. The standard deviation of the interval between impulses is 20-30% of the mean interval for a wide range of frequencies of the tonic motoneurones. This large scatter is tolerable because the slow muscle fibres are sluggish and because the eyecup is also visually stabilized by a system of long time-constant. 4. In roll the two eyecups move in opposite directions relative to the midline of the animal. In pitch the two eyecups move in the same direction relative to the body of the animal, but in neither case is there a correlation between individual impulses to the muscles of the right and left eyecups which are active at the same time. 5. Possible mechanisms of linkage between the two eyecups are discussed.

scholarly journals Observations on the Reactions of Marine Plankton to Light

1933 ◽  
Vol 19 (1) ◽  
pp. 385-438 ◽  
Author(s):  
G. M. Spooner
Keyword(s):  
The Body ◽  
Direct Result ◽  
Marine Plankton ◽  
Marine Animals ◽  
Free Living ◽  
Directed Movement ◽  
Wide Range ◽  
The Mean ◽  
The Vertical Distribution ◽  
Formation Of Groups

1. The most noticeable response of marine plankton to light, under laboratory conditions, is the formation of groups on the lighted (or opposite) side of the vessel containing them.2. Specimens from such groups were tested under different conditions of illumination, and in all cases they moved in the direction of the light quite irrespective of accompanying changes of intensity in the surroundings.3. Groups form around the line of direction of the light, or the resultant direction when the light is scattered or falling from more directions than one, this being the direct result of individuals moving along the mean path of incidence of the light.4. The behaviour of individuals was examined more closely to distinguish between the two possible ways in which the directed movement could have been brought about, viz. (i) reactions to bilateral inequalities of illumination (here called “true topotaxis”), and (ii) reactions to changes in total illumination of light-receptors (a type of “phobotaxis”). For a number of species it was clearly a case of “true topotaxis,” and very probably for at least the majority of the rest.5. In two very different cases, namely, Acartia clausi and Poecilochaetus serpens, there was no orientation of the body, but nevertheless efficient orientation of the path of movement. It is believed that this is the first occasion on which such behaviour has been described.6. The observations described point to the fact that movement in the direction of incidence of the light, however this may be affected, is general among a wide range of the smaller, free-living, bilaterally symmetrical, marine animals, and would tend to dominate other possible response to light. This behaviour on the part of individuals provides a substantial basis for attempted explanations of the correlations, that have been demonstrated by ecological workers, between the vertical distribution of populations and light-intensity.

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