Kinetic Theory for a Dilute Gas of Particles with "Spin"

1971 ◽  
Vol 26 (6) ◽  
pp. 1057-1071 ◽  
Author(s):  
S. Hess ◽  
L. Waldmann

Abstract The Senftleben-Beenakker effect of the viscosity of dilute polyatomic gases is investigated theoretically for the case where an alternating magnetic field parallel to the usual static field is present. The starting point is a set of transport-relaxation equations obtained from the kinetic equation for the one-particle distribution by application of the moment method. The transport-relaxation equations are solved for the viscosity problem and the relevant viscosity coefficients averaged over many periods of the oscillating field are calculated as functions of the frequency of the alternating field and of the magnitudes of both magnetic fields. The importance of the obtained results for the dynamic behaviour of the thermomagnetic gas torque (Scott effect) is discussed.

1968 ◽  
Vol 23 (12) ◽  
pp. 1911-1913
Author(s):  
Siegfried Hess

The influence of a magnetic field on the diffusion of Brownian particles with a magnetic moment parallel to their internal angular momentum is discussed. Starting point is a generalized Fokker-Planck equation. Application of the moment method leads to a set of transport-relaxation equations. From them the diffusion tensor depending on the external field is inferred.


Author(s):  
Mahdieh Gholizadeh ◽  
Mohammad Hossein Gholizadeh ◽  
Hossein Ghayoumi Zadeh ◽  
Mostafa Danaeian

Background: This paper presents a method to improve medical radiography images based on the use of statistical signal moments. Methods: In this paper, the image with noise is considered as a statistical signal, and the noise reduction is performed by using fractional moments. The fractional moment’s method, on the one hand, has a speed similar to the moment method, and, on the other hand, has not the limitations of the moment method, which sometimes achieves inaccurate results. The proposed method is ultimately examined on radiographic images (CT). Results: The information obtained from the fractional moments of the received signal is a criterion to estimate the noise parameters and the gray scales of the main image. One of the limitations of the proposed method is that the image should be sent several times, because in statistical discussions, we cannot make a decision with only one sample. The error of the proposed noise reduction method in terms of the number of times the original image was sent, is about 0.009, 0.0009, 0.0002, and 0.0001, for n = 3, n = 6, n = 9 and n = 14, respectively. Conclusion: The simulation results show that the proposed method is more effective than the most conventional noise reduction methods, both in the low signal to noise ratio and in terms of image quality, and is more powerful than the most notable noise removal methods in restoring the subtleties and image details.


2021 ◽  
Vol 4 (1) ◽  
pp. 104-125
Author(s):  
Alina Patrakova

The article traces how the life-death boundary in the intensive care unit is made visible on hospital monitors (in figures and diagnostic images), in medical dramas and docu-series as well as via video surveillance. The starting point is the question of how much the life-death boundary is accessible to be viewed directly – not only with the naked eye, but also with the help of special devices. In search for answers to this question, the author focuses on the semantic field of the “screen” concept. Screen, on the one hand, can be considered as a surface on which an image is projected; on the other hand, it can be a pro-tective barrier. In other words, screen can be a tool for both turning the invisible into the visible and vice versa. This antinomy between visibility and invisibility can be traced both in relation to hospital monitors as well as to TV and video surveillance. Screen has its frames and technical limitations that determine the selectivity of representation. In conclusion, the author assumes that the intention to objectively record the moment of death, to make this boundary clearly visible from a scientific point of view makes it, on the contrary, escape the eye. What is managed to be registered and made visible turns out to be an artifact. In this sense, the life-death boundary in critical medicine appears as a multiple construct – of theoretical, technological, and socio-cultural nature. Probably, the paradox is that this transition from life to death can be seen more clearly with the naked eye rather than with diagnostic and monitoring technologies.


2020 ◽  
Vol 2020 (10-2) ◽  
pp. 86-98
Author(s):  
Ivan Popov

The paper deals with the organization and decisions of the conference of the Minister-Presidents of German lands in Munich on June 6-7, 1947, which became the one and only meeting of the heads of the state governments of the western and eastern occupation zones before the division of Germany. The conference was the first experience of national positioning of the regional elite and clearly demonstrated that by the middle of 1947, not only between the allies, but also among German politicians, the incompatibility of perspectives of further constitutional development was existent and all the basic conditions for the division of Germany became ripe. Munich was the last significant demonstration of this disunity and the moment of the final turn towards the three-zone orientation of the West German elite.


2012 ◽  
pp. 66-80
Author(s):  
Michał Mrozowicki

Michel Butor, born in 1926, one of the leaders of the French New Novel movement, has written only four novels between 1954 and 1960. The most famous of them is La Modification (Second thoughts), published in 1957. The author of the paper analyzes two other Butor’s novels: L’Emploi du temps (Passing time) – 1956, and Degrés (Degrees) – 1960. The theme of absence is crucial in both of them. In the former, the novel, presented as the diary of Jacques Revel, a young Frenchman spending a year in Bleston (a fictitious English city vaguely similar to Manchester), describes the narrator’s struggle to survive in a double – spatial and temporal – labyrinth. The first of them, formed by Bleston’s streets, squares and parks, is symbolized by the City plan. During his one year sojourn in the city, using its plan, Revel learns patiently how to move in its different districts, and in its strange labyrinth – strange because devoid any centre – that at the end stops annoying him. The other, the temporal one, symbolized by the diary itself, the labyrinth of the human memory, discovered by the narrator rather lately, somewhere in the middle of the year passed in Bleston, becomes, by contrast, more and more dense and complex, which is reflected by an increasinly complex narration used to describe the past. However, at the moment Revel is leaving the city, he is still unable to recall and to describe the events of the 29th of February 1952. This gap, this absence, symbolizes his defeat as the narrator, and, in the same time, the human memory’s limits. In Degrees temporal and spatial structures are also very important. This time round, however, the problems of the narration itself, become predominant. Considered from this point of view, the novel announces Gerard Genette’s work Narrative Discourse and his theoretical discussion of two narratological categories: narrative voice and narrative mode. Having transgressed his narrative competences, Pierre Vernier, the narrator of the first and the second parts of the novel, who, taking as a starting point, a complete account of one hour at school, tries to describe the whole world and various aspects of the human civilization for the benefit of his nephew, Pierre Eller, must fail and disappear, as the narrator, from the third part, which is narrated by another narrator, less audacious and more credible.


2021 ◽  
pp. 053901842199894
Author(s):  
Frank Adloff ◽  
Iris Hilbrich

Possible trajectories of sustainability are based on different concepts of nature. The article starts out from three trajectories of sustainability (modernization, transformation and control) and reconstructs one characteristic practice for each path with its specific conceptions of nature. The notion that nature provides human societies with relevant ecosystem services is typical of the path of modernization. Nature is reified and monetarized here, with regard to its utility for human societies. Practices of transformation, in contrast, emphasize the intrinsic ethical value of nature. This becomes particularly apparent in discourses on the rights of nature, whose starting point can be found in Latin American indigenous discourses, among others. Control practices such as geoengineering are based on earth-systemic conceptions of nature, in which no distinction is made between natural and social systems. The aim is to control the earth system as a whole in order for human societies to remain viable. Practices of sustainability thus show different ontological understandings of nature (dualistic or monistic) on the one hand and (implicit) ethics and sacralizations (anthropocentric or biocentric) on the other. The three reconstructed natures/cultures have different ontological and ethical affinities and conflict with each other. They are linked to very different knowledge cultures and life-worlds, which answer very differently to the question of what is of value in a society and in nature and how these values ought to be protected.


Author(s):  
Gerandy Brito ◽  
Ioana Dumitriu ◽  
Kameron Decker Harris

Abstract We prove an analogue of Alon’s spectral gap conjecture for random bipartite, biregular graphs. We use the Ihara–Bass formula to connect the non-backtracking spectrum to that of the adjacency matrix, employing the moment method to show there exists a spectral gap for the non-backtracking matrix. A by-product of our main theorem is that random rectangular zero-one matrices with fixed row and column sums are full rank with high probability. Finally, we illustrate applications to community detection, coding theory, and deterministic matrix completion.


1998 ◽  
Vol 11 (1) ◽  
pp. 565-565
Author(s):  
G. Cayrel de Strobel ◽  
R. Cayrel ◽  
Y. Lebreton

After having studied in great detail the observational HR diagram (log Teff, Mbol) composed by 40 main sequence stars of the Hyades (Perryman et al.,1997, A&A., in press), we have tried to apply the same method to the observational main sequences of the three next nearest open clusters: Coma Berenices, the Pleiades, and Praesepe. This method consists in comparing the observational main sequence of the clusters with a grid of theoretical ZAMSs. The stars composing the observational main sequences had to have reliable absolute bolometric magnitudes, coming all from individual Hipparcos parallaxes, precise bolometric corrections, effective temperatures and metal abundances from high resolution detailed spectroscopic analyses. If we assume, following the work by Fernandez et al. (1996, A&A,311,127), that the mixing-lenth parameter is solar, the position of a theoretical ZAMS, in the (log Teff, Mbol) plane, computed with given input physics, only depends on two free parameters: the He content Y by mass, and the metallicity Z by mass. If effective temperature and metallicity of the constituting stars of the 4 clusters are previously known by means of detailed analyses, one can deduce their helium abundances by means of an appropriate grid of theoretical ZAMS’s. The comparison between the empirical (log Teff, Mbol) main sequence of the Hyades and the computed ZAMS corresponding to the observed metallicity Z of the Hyades (Z= 0.0240 ± 0.0085) gives a He abundance for the Hyades, Y= 0.26 ± 0.02. Our interpretation, concerning the observational position of the main sequence of the three nearest clusters after the Hyades, is still under way and appears to be greatly more difficult than for the Hyades. For the moment we can say that: ‒ The 15 dwarfs analysed in detailed in Coma have a solar metallicity: [Fe/H] = -0.05 ± 0.06. However, their observational main sequence fit better with the Hyades ZAMS. ‒ The mean metallicity of 13 Pleiades dwarfs analysed in detail is solar. A metal deficient and He normal ZAMS would fit better. But, a warning for absorption in the Pleiades has to be recalled. ‒ The upper main sequence of Praesepe, (the more distant cluster: 180 pc) composed by 11 stars, analysed in detail, is the one which has the best fit with the Hyades ZAMS. The deduced ‘turnoff age’ of the cluster is slightly higher than that of the Hyades: 0.8 Gyr instead of 0.63 Gyr.


2004 ◽  
Vol 5 (1) ◽  
pp. 43-58
Author(s):  
Jeffrey S. Galko ◽  

The ontological question of what there is, from the perspective of common sense, is intricately bound to what can be perceived. The above observation, when combined with the fact that nouns within language can be divided between nouns that admit counting, such as ‘pen’ or ‘human’, and those that do not, such as ‘water’ or ‘gold’, provides the starting point for the following investigation into the foundations of our linguistic and conceptual phenomena. The purpose of this paper is to claim that such phenomena are facilitated by, on the one hand, an intricate cognitive capacity, and on the other by the complex environment within which we live. We are, in a sense, cognitively equipped to perceive discrete instances of matter such as bodies of water. This equipment is related to, but also differs from, that devoted to the perception of objects such as this computer. Behind this difference in cognitive equipment underlies a rich ontology, the beginnings of which lies in the distinction between matter and objects. The following paper is an attempt to make explicit the relationship between matter and objects and also provide a window to our cognition of such entities.


Sign in / Sign up

Export Citation Format

Share Document