Improved determination of the position and activity of a radioactive point source inside a bulky medium using several detectors. The special case of a lung counter—A general view

2007 ◽  
Vol 65 (2) ◽  
pp. 234-238
Author(s):  
Omer Pelled ◽  
Mauro L. Bonardi ◽  
Uzi German ◽  
Flavia Groppi ◽  
Zeev B. Alfassi
1997 ◽  
Vol 05 (03) ◽  
pp. 243-263 ◽  
Author(s):  
A. Charalambopoulos ◽  
G. Dassios ◽  
P. Ergatis

A small, acoustically hard and axisymmetric object is placed in a deep homogeneous sea environment with a hard plane bottom. The free surface of the sea is assumed to be soft. The source and the receiver are placed on the same vertical line, far away from the object. Given the positions of the source and the receiver, two problems are solved: the determination of the pressure field at the receiver from the position and the shape of the object, and the determination of the position and the shape of the object from the pressure field at the receiver. The special case of smooth objects generated by the rotation of differentiable curves is studied. We provide results for the case of a floating object and for the case of an object or a boss at the bottom of the sea.


Author(s):  
Dr. G. Kaemof

A mixture of polycarbonate (PC) and styrene-acrylonitrile-copolymer (SAN) represents a very good example for the efficiency of electron microscopic investigations concerning the determination of optimum production procedures for high grade product properties.The following parameters have been varied:components of charge (PC : SAN 50 : 50, 60 : 40, 70 : 30), kind of compounding machine (single screw extruder, twin screw extruder, discontinuous kneader), mass-temperature (lowest and highest possible temperature).The transmission electron microscopic investigations (TEM) were carried out on ultra thin sections, the PC-phase of which was selectively etched by triethylamine.The phase transition (matrix to disperse phase) does not occur - as might be expected - at a PC to SAN ratio of 50 : 50, but at a ratio of 65 : 35. Our results show that the matrix is preferably formed by the components with the lower melting viscosity (in this special case SAN), even at concentrations of less than 50 %.


1949 ◽  
Vol 2 (4) ◽  
pp. 469
Author(s):  
W Freiberger ◽  
RCT Smith

In this paper we discuss the flexure of an incomplete tore in the plane of its circular centre-line. We reduce the problem to the determination of two harmonic functions, subject to boundary conditions on the surface of the tore which involve the first two derivatives of the functions. We point out the relation of this solution to the general solution of three-dimensional elasticity problems. The special case of a narrow rectangular cross-section is solved exactly in Appendix II.


1998 ◽  
Vol 13 (02) ◽  
pp. 83-86 ◽  
Author(s):  
MARCO LOMBARDI

In this letter we provide a new proof of a general theorem on gravitational lenses, first proven by Burke (1981) for the special case of thin lenses. The theorem states that a transparent gravitational lens with non-singular mass distribution produces an odd number of images of a point source. Our general proof shows that the topological degree finds natural and interesting applications in the theory of gravitational lenses.


1963 ◽  
Vol 14 (2) ◽  
pp. 105-124 ◽  
Author(s):  
Derek F. Lawden

SummaryThe development during the last two decades of analytical techniques for the solution of problems relating to the optimisation of rocket trajectories is outlined and the present position in this field of research is summarised. It is shown that the determination of optimal trajectories in a general gravitational field can be expressed as a Mayer problem from the calculus of variations. The known solution to such a problem is stated and applied, first to the special case of the launching of an artificial satellite into a circular orbit with minimum expenditure of propellant and, secondly, to the general astronautical problem of the economical transfer of a rocket between two terminals in a gravitational field. The special cases when the field is uniform and when it obeys an inverse square law of attraction to a point are then considered, and the paper concludes with some remarks concerning areas in which further investigations are necessary.


2014 ◽  
pp. 108-134 ◽  
Author(s):  
Agustin Udias ◽  
Raul Madariaga ◽  
Elisa Buforn

2019 ◽  
pp. 68-75
Author(s):  
A. S. Fomochkina ◽  
V. G. Bukchin

Alongside the determination of the focal mechanism and source depth of an earthquake by direct examination of their probable values on a grid in the parameter space, also the resolution of these determinations can be estimated. However, this approach requires considerable time in the case of a detailed search. A special case of a shallow earthquake whose one nodal plane is subhorizontal is an example of the sources that require the use of a detailed grid. For studying these events based on the records of the long-period surface waves, the grids with high degree of detail in the angles of the focal mechanism are required. We discuss the application of the methods of parallel computing for speeding up the calculations of earthquake parameters and present the results of studying the strongest aftershock of the Tohoku, Japan, earthquake by this approach.


2005 ◽  
Vol 19 (3) ◽  
pp. 595-642
Author(s):  
Claude Masse

The following article deals with the problem of « misuse of office » in the principal-agent relationship under Quebec civil law. Despite the abundance of case law, solutions to the problem are not well defined especially in cases involving personality defects of the agent. The law concerning « misuse of office » is generally to be found in article 1054(7) of the Quebec Civil Code concerning the liability of principals. This controverted article not only deals with the liability of masters for servants, but also with the problem of torts committed by agents (art. 1731 C.C.). It also has an effect on workmen's compensation laws. The main issue in « misuse of office » is the determination of what constitutes a carrying out of duties within the scope of employment. The principal can only be held liable for the tort of an agent if three conditions are met : the tort feasor must have been his agent ; he must have committed a wrongful act ; and this act must have been committed in the scope of his employment. After a general view of the fundamental principles involved, the paper defines « misuse of office » as « all torts committed by an agent in the exercice of his duties, even when not authorized to carry out the duties in the manner which he did, but where the activity is designed to benefit his principal ». The only case where the principal escapes liability is where the agent committed a tort which did not involve his work. The agent in that case no longer acts for the benefit of his principal, but is pursuing his personal interest. The principal is then no longer held liable. Determination of the notion of « benefit » therefore becomes essential. Far from being a simple question of monetary profit, it is extended to mean any activity which can serve the principal's enterprise, whether in the improvement of public relations, or of relations with staff or suppliers. The pecuniary gain becomes but one element amongst many others. It is not even necessary for the benefit to ever materialize. The simple fact that the intention was to benefit the principal is sufficient. The review of the case law leads the author to conclude that the modification of the ways in which the duties are carried out has little effect on the liability of the principal. For instance, the agent can change the time, the place and the manner of performance and still engage the liability of the principal. Quebec courts have gone even further. They have held that an agent can go beyond the usual scope of his duties or take up some that he was not authorized to do, without affecting the liability of the principal. In fact, Quebec courts have developed a broad interpretation of the notion of duty. They consider that the agent is called upon to perform tasks more or less accessory to his main duties and thus extend the principal's liability to all of them. As already stated, the notion of «benefit to the principal» is a determining factor. It is not necessary that the agent's work for the principal be exclusive. The agent that derives a personal benefit and simultaneously intends to benefit the principal, will still be considered to have performed an act in the course of his duties. The paper examines a series of problems involving the personality of the agent. Certain tortious acts can be committed in relations with third parties or co-workers, and are the direct result of a personality defect of the agent. Such is the case of a restaurant worker who physically attacks a client as the result of a dispute or of the agent stealing from a client. The paper points out the great difficulty that Quebec courts have experienced in the legal qualification of this situation. After an in-depth study of the Quebec case law, the paper concludes that the trend is to maintain the liability of the principal in these cases. One criterion appears to be well defined : the principal bears the responsibility, when hiring someone, to assure his clients or the persons with whom he does business, that he will respect their property as well as their moral and physical integrity. The necessary tie between the duties of the agent and the relationship with persons coming in contact with him, will engage the liability of the principal. Every time the agent comes in contact with a person in the carrying out of business, the principal will be held responsible for the damage resulting from personality defects of the agent. In all other cases, the relation will be considered personal to the agent and the principal will be relieved of any liability.


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