Combined retractor and hand-rest system for neurosurgery

1984 ◽  
Vol 7 (2-3) ◽  
pp. 85-87 ◽  
Author(s):  
Joachim M. Gilsbach ◽  
Theodor Lutze ◽  
Wolfgang Seeger
Keyword(s):  
1987 ◽  
Vol 65 (5) ◽  
pp. 527-529
Author(s):  
A. C. Saha ◽  
M. M. Samanta ◽  
D. K. Pal ◽  
R. N. Nandy ◽  
B. K. Bandopadhyay

Production of pions through the intermediate state called fireballs has been considered to study the energy distribution of pions in the fireball-rest system. Nikfi-R-type photoemulsion plates exposed to the 70-GeV proton beam of the Surpukhov Accelerator, Dubna, USSR, are used for this purpose. A graphical representation of the distribution of energies among the pions is shown. It is observed that this distribution closely resembles Planck's distribution of photons. Furthermore, this study reveals that the Maxwell–Boltzmann distribution deviates greatly from experimental observations. The average energy of the pions is found to be (0.770 ± 0.03) GeV.


2021 ◽  
pp. 1-6
Author(s):  
Robert J Buenker ◽  

One of the most basic principles in science is the objectivity of measurement of physical properties. According to the special theory of relativity (STR), this ancient principle is violated for observers in relative motion since it predicts that they generally will disagree on the ratios of the lengths of two objects and also on whose clock is running slower at any given time. Both predictions stem from the Lorentz transformation (LT), which is the centerpiece of Einstein's STR. It has recently been pointed out that two of the claims of this theory are mutually contradictory; it is impossible that the rates of two clocks in motion are strictly proportional to one another (time dilation) while one of them finds that two events are simultaneous whereas the other does not (remote nonsimultaneity). This recognition proves that the LT is not a valid component of the relativistic theory of motion, including its well-known thesis that space and time are not distinct quantities. Instead, it has always been found experimentally that the rates of clocks in motion are governed by a Universal Timedilation Law (UTDL), whereby the speed of the clock relative to a specific rest system is the sole determining factor. A simple way of describing this state of affairs is to say that the standard unit of time in each rest frame is different and increases with its relative speed to the above rest system by a definite factor. The measurement process is thereby rendered to be completely objective in nature. A key goal of relativity theory is therefore to develop a quantitatively valid method for determining this factor. It will be shown that the same factor appears in the true relativistic space-time transformation and that it also plays a key role in the uniform scaling of all other physical properties


1953 ◽  
Vol 31 (1) ◽  
pp. 1-10 ◽  
Author(s):  
S. Shanmugadhasan

The antisymmetric spin tensor of rank two used to describe the rotational motion of a particle is assumed to satisfy the constraint condition that the velocity 4-vector is orthogonal to it. Since the dipole moment is proportional to the spin tensor, this condition leads always to a purely magnetic dipole in the rest system of the particle. Frenkel has indicated how the action principle for the classical equations of motion can be set up treating the above constraint condition as a supplementary condition. The Hamiltonian dynamics of a system having supplementary conditions and Lagrange undetermined multipliers has been discussed recently by Dirac. Dirac's method and results previously obtained give the required Hamilton–Jacobi equations and Poisson Brackets of the dynamical variables. The cases where the particle behaves like a pure gyroscope and a symmetrical top are treated. When there is an interacting field, it is assumed that the action of the Held is given by the effective 4-vector potential without further specification. The orthogonality of the velocity to the tensor dual to the spin tensor can be imposed as an alternative constraint condition. This possibility is discussed briefly. The quantum formulation is completed with the help of the standard analogy rules.


A classification of particles is suggested based on a Ũ (12) symmetry scheme. This is a relativistic generalization of the U (6) symmetry. The spin 1 2 and 3 2 baryons are each described by 20-component spinors which satisfy Bargmann-Wigner equations and belong to the 3̲6̲4̲ representation of the Ũ (12) group while the vector and p. s. mesons belong to the representation 1̲4̲3̲. The procedure for writing fully relativistic form factors is worked out in detail for baryon-meson and meson-meson cases. The new results are the following: (1) F C ( q 2 ) F M ( q 2 ) ∝ 1 + q 2 < 2 μ > m , Where F c and F M are (Sachs) electromagnetic form factors. (2) μ D = 1 + 2 m /< μ >, where < μ > is the mean mass of the 1 - multiplet and m the nucleon mass. (3) μ ρ,K* = 3. The conventional U (6) results can be recovered by projecting to the positive energy subspace in the rest system for each particle. To any irreducible representation of the U (6) there corresponds one irreducible representation of Ũ (12) and vice versa.


2020 ◽  
Vol 1 ◽  
pp. 1067-1076
Author(s):  
S. Revfi ◽  
J. Wilwer ◽  
K. Behdinan ◽  
A. Albers

AbstractMaturity levels of components in early phases of product development are often assessed with Technology Readiness Levels. However, developing Multi-Material-Design (MMD) concepts for lightweight design, not only the manufacturability of the individual components is decisive, but also their joinability with each other and their integration into the rest system. This paper presents an approach for the evaluation of maturity levels of MMD concepts on the basis of cardinal coefficients considering a time forecast of the manufacturing and joining technologies required in the concept.


2011 ◽  
Vol 464 ◽  
pp. 717-720
Author(s):  
Si Yong Wang ◽  
Zhi Hua Feng ◽  
Fan Lv

In order to release the influence of shedding motion on warp tension fluctuation, easing device is often set on short looms with single back rest system. With the decrease of the beam’s diameter, the wrapping angle formed by warp and the active back rest will become bigger, and the effect of the easing device will be more significant. However, the wrapping angle of the double back rest system is a constant while the change of the beam’s diameter. The effect of easing device on air-jet looms of double back rests system is analyzed in this paper, and conclusion has been made that the easing device can be eliminated on the double back rests system.


2010 ◽  
Vol 43 ◽  
pp. 722-725
Author(s):  
Lang Sun ◽  
Zhi Hua Feng ◽  
Si Yong Wang

The dynamic model of the back-rest system of type WG-2000 air-jet loom is set up and the relevant nonlinear vibration analysis is investigated when principal parametric resonance is taken into consideration. Results show that the system will be unstable when the corresponding frequency of the rotating-speed meets Ω≈2ω0/n, it may have unstable region. The higher speed is, the wider the region is. The nonlinear dynamic analysis of the back-rest system can be benefit for engineering design and improvement of weaving technology.


2016 ◽  
Vol 8 (3) ◽  
pp. 259-265
Author(s):  
S. A. Bhuiyan ◽  
A. R. Baizid

Lorentz Transformations generally describe the transformations for observations between mechanical phenomenon systems in relative motion. We all know that the electrical charge of associate isolated system is relativistically invariant. We have studied the volume charge density in Special and Most General Lorentz Transformations. If one frame moves on x-axis then we will notice this in Special Lorentz Transformation. On the other hand if the motion of the moving frame is not on the x-axis relative to the rest frame however the motion is on any arbitrary direction then we will notice this formula for the Most General Lorentz Transformation. We also investigated the changes of the volume charge density of moving system in terms of that of rest system in Most General Lorentz Transformations at different angles and velocities.


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