168 research outputs found
The converse problem for the multipotentialisation of evolution equations and systems
We propose a method to identify and classify evolution equations and systems
that can be multipotentialised in given target equations or target systems. We
refer to this as the {\it converse problem}. Although we mainly study a method
for -dimensional equations/system, we do also propose an extension of
the methodology to higher-dimensional evolution equations. An important point
is that the proposed converse method allows one to identify certain types of
auto-B\"acklund transformations for the equations/systems. In this respect we
define the {\it triangular-auto-B\"acklund transformation} and derive its
connections to the converse problem. Several explicit examples are given. In
particular we investigate a class of linearisable third-order evolution
equations, a fifth-order symmetry-integrable evolution equation as well as
linearisable systems.Comment: 31 Pages, 7 diagrams, submitted for consideratio
Comment on the Shiner-Davison-Landsberg Measure
The complexity measure from Shiner et al. [Physical Review E 59, 1999, 1459-1464] (henceforth abbreviated as SDL-measure) has recently been the subject of a fierce debate. We discuss the properties and shortcomings of this measure, from the point of view of our recently constructed fundamental, statistical mechanics-based measures of complexity Cs(Îł,ÎČ) [Stoop et al., J. Stat. Phys. 114, 2004, 1127-1137]. We show explicitly, what the shortcomings of the SDL-measure are: It is over-universal, and the implemented temperature dependence is trivial. We also show how the original SDL-approach can be modified to rule out these points of critique. Results of this modification are shown for the logistic parabol
Lyapunov exponent and natural invariant density determination of chaotic maps: An iterative maximum entropy ansatz
We apply the maximum entropy principle to construct the natural invariant
density and Lyapunov exponent of one-dimensional chaotic maps. Using a novel
function reconstruction technique that is based on the solution of Hausdorff
moment problem via maximizing Shannon entropy, we estimate the invariant
density and the Lyapunov exponent of nonlinear maps in one-dimension from a
knowledge of finite number of moments. The accuracy and the stability of the
algorithm are illustrated by comparing our results to a number of nonlinear
maps for which the exact analytical results are available. Furthermore, we also
consider a very complex example for which no exact analytical result for
invariant density is available. A comparison of our results to those available
in the literature is also discussed.Comment: 16 pages including 6 figure
Function reconstruction as a classical moment problem: A maximum entropy approach
We present a systematic study of the reconstruction of a non-negative
function via maximum entropy approach utilizing the information contained in a
finite number of moments of the function. For testing the efficacy of the
approach, we reconstruct a set of functions using an iterative entropy
optimization scheme, and study the convergence profile as the number of moments
is increased. We consider a wide variety of functions that include a
distribution with a sharp discontinuity, a rapidly oscillatory function, a
distribution with singularities, and finally a distribution with several spikes
and fine structure. The last example is important in the context of the
determination of the natural density of the logistic map. The convergence of
the method is studied by comparing the moments of the approximated functions
with the exact ones. Furthermore, by varying the number of moments and
iterations, we examine to what extent the features of the functions, such as
the divergence behavior at singular points within the interval, is reproduced.
The proximity of the reconstructed maximum entropy solution to the exact
solution is examined via Kullback-Leibler divergence and variation measures for
different number of moments.Comment: 20 pages, 17 figure
The Partition Function and Level Density for Yang-Mills-Higgs Quantum Mechanics
We calculate the partition function and the asymptotic integrated
level density for Yang-Mills-Higgs Quantum Mechanics for two and three
dimensions (). Due to the infinite volume of the phase space
on energy shell for , it is not possible to disentangle completely the
coupled oscillators (-model) from the Higgs sector. The situation is
different for for which is finite. The transition from order
to chaos in these systems is expressed by the corresponding transitions in
and , analogous to the transitions in adjacent level spacing
distribution from Poisson distribution to Wigner-Dyson distribution. We also
discuss a related system with quartic coupled oscillators and two dimensional
quartic free oscillators for which, contrary to YMHQM, both coupling constants
are dimensionless.Comment: 10 pages, LaTeX; minor changes; version accepted for publication as a
Letter in J. Phys.
A unification in the theory of linearization of second order nonlinear ordinary differential equations
In this letter, we introduce a new generalized linearizing transformation
(GLT) for second order nonlinear ordinary differential equations (SNODEs). The
well known invertible point (IPT) and non-point transformations (NPT) can be
derived as sub-cases of the GLT. A wider class of nonlinear ODEs that cannot be
linearized through NPT and IPT can be linearized by this GLT. We also
illustrate how to construct GLTs and to identify the form of the linearizable
equations and propose a procedure to derive the general solution from this GLT
for the SNODEs. We demonstrate the theory with two examples which are of
contemporary interest.Comment: 8 page
Teilhabe an Gesundheit von Menschen mit BeeintrÀchtigung wÀhrend der Corona-Pandemie (TaG-Co-Studie) : Ergebnisbericht
Hintergrund und Zielsetzung: Die derzeitige Corona-Pandemie bringt seit dem FrĂŒhjahr 2020 viele VerĂ€nderungen fĂŒr Menschen weltweit mit sich. Menschen mit BeeintrĂ€chtigung, die in Einrichtungen der Eingliederungshilfe leben und arbeiten, weisen hĂ€ufig ein erhöhtes Risiko fĂŒr einen schwereren Krankheitsverlauf bei der Infektion mit Covid-19 auf und sind in besonderem MaĂ von den Vorgaben und EinschrĂ€nkungen wĂ€hrend der Corona-Pandemie betroffen. Auch das Fachpersonal in Einrichtungen der Eingliederungshilfe steht seit Beginn der Pandemie vor Herausforderungen. Die mit der Corona-Pandemie einhergehenden MaĂnahmen zur EindĂ€mmung der Pandemie haben Auswirkungen auf die Teilhabe an Gesundheit von Menschen mit BeeintrĂ€chtigung. Ziel der TaG-Co-Studie ist es, die Teilhabe an Gesundheit von Menschen mit BeeintrĂ€chtigung wĂ€hrend der Corona-Pandemie zu untersuchen. Dabei stehen neben den Vorgaben zur Expositionsprophylaxe auch der Umgang mit Gesundheitsinformationen, der Zugang und die Inanspruchnahme des Gesundheitswesens, PrĂ€ventions- und Gesundheitsangebote, das ErnĂ€hrungsverhalten und der Substanzmittelkonsum sowie die Gestaltung von Kontakten zu Angehörigen und Bezugspersonen wĂ€hrend der Pandemie im Zentrum der Studie. DarĂŒber hinaus wird die Rolle der FachverbĂ€nde und Einrichtungen fĂŒr Menschen mit Behinderung wĂ€hrende der Corona-Pandemie bei der Teilhabe an Gesundheit von Menschen mit BeeintrĂ€chtigung untersucht.
Methodik: Im Rahmen einer qualitativen PrimĂ€rerhebung wurden bundesweit (auĂer Berlin, Bremen, Hamburg und Saarland) leitfadengestĂŒtzte Telefoninterviews mit n=12 Leitungs- und Fachpersonen von Einrichtungen fĂŒr Menschen mit Behinderung im Bereich Wohnen sowie n=4 Vertreter*innen von Bundes- und FachverbĂ€nden fĂŒr Menschen mit BeeintrĂ€chtigung von November bis Dezember 2020 gefĂŒhrt. Die Interviews wurden mittels der qualitativen Inhaltsanalyse nach Kuckartz ausgewertet.
Ergebnisse: Verordnungen zur Expositionsprophylaxe und KontaktbeschrĂ€nkung wurden in den Einrichtungen meist gut umgesetzt; eine permanente Einhaltung der Hygienekonzepte stellte fĂŒr das Fachpersonal aufgrund der schweren Vereinbarkeit mit den AblĂ€ufen der Pflege allerdings eine groĂe Herausforderung dar. In vielen Einrichtungen wurden Gesundheitsinformationen in Bezug auf die Corona-Pandemie in âKrisenteamsâ besprochen und in Leichter Sprache zur VerfĂŒgung gestellt. Die meisten Vorsorgeuntersuchungen und Gesundheitsangebote wurden wĂ€hrend der Corona-Pandemie nicht durchgefĂŒhrt. Die Einrichtungen berichteten von positiven VerĂ€nderungen im ErnĂ€hrungsverhalten bei den Bewohner*innen aufgrund der Besuchs- und KontaktbeschrĂ€nkungen. Es konnten keine VerĂ€nderungen des Alkohol- oder Tabakkonsums im stationĂ€ren Bereich bepbachtet werden. Dagegen zeigte sich im ambulant betreuten Wohnbereich eine Zunahme des Alkohol- und Medikamentenkonsums, insbesondere bei Klient*innen mit psychischen BeeintrĂ€chtigungen. Zur GewĂ€hrleistung der sozialen Teilhabe ermöglichten die Einrichtungen Alternativen, bspw. GesprĂ€che am offenen Fenster oder digitale Formate (z. B. Skype). EinschrĂ€nkungen wie die SchlieĂungen der WerkstĂ€tten, fĂŒhrten bei einigen Bewohner*innen zu Ănderungen des Verhaltens, wie sozialer RĂŒckzug oder unruhiges und aggressives Verhalten. Auf Ebene der FachverbĂ€nde wurden neue Formate (bspw. Newsletter oder Fachforen) zur Weiterleitung von Informationen wĂ€hrend der Corona-Pandemie geschaffen. Als problematisch thematisierten die FachverbĂ€nde, dass die technische Ausstattung der Einrichtungen vielfach nicht ausreichend sei und digitale Angebote nicht genutzt werden können. WĂ€hrend der Pandemie steht der Infektionsschutz der Menschen mit BeeintrĂ€chtigung neben dem Austausch mit Bundes- und Landesbehörden im Vordergrund der Arbeit der FachverbĂ€nde, in dem u. a. Konzepte zur Reduzierung des Ansteckungsrisikos entwickelt werden.
Schlussfolgerungen: Auch wenn die Einrichtungen der Eingliederungshilfe die Herausforderungen durch die Corona-Pandemie auf vielfĂ€ltige Weise bewĂ€ltigen, besteht groĂer Bedarf um die Einrichtungen von Seiten der FachverbĂ€nde und der Politik zu unterstĂŒtzen. Einrichtungsleitungen und Fachpersonal in Einrichtungen fĂŒr Menschen mit BeeintrĂ€chtigung benötigen Konzepte, die aus der Praxiserfahrung heraus entwickelt werden, um die Klient*innen vor einer Ansteckung mit dem Coronavirus zu schĂŒtzen. DarĂŒber hinaus dĂŒrfen die sozialen Aspekte der Teilhabe und die individuellen Besonderheiten der Menschen mit BeeintrĂ€chtigung nicht vernachlĂ€ssigt werden. Nur so kann auch wĂ€hrend der Corona-Pandemie die Teilhabe an Gesundheit von Menschen mit BeeintrĂ€chtigung gewĂ€hrleistet werden
Jejunal microvilli atrophy and reduced nutrient transport in rats with advanced liver cirrhosis: improvement by Insulin-like Growth Factor I
BACKGROUND: Previous results have shown that in rats with non-ascitic cirrhosis there is an altered transport of sugars and amino acids associated with elongated microvilli. These alterations returned to normal with the administration of Insulin-Like Growth Factor-I (IGF-I). The aims of this study were to explore the evolution of these alterations and analyse the effect of IGF-I in rats with advanced cirrhosis and ascites. Thus, jejunal structure and nutrient transport (D-galactose, L-leucine, L-proline, L-glutamic acid and L-cystine) were studied in rats with ascitic cirrhosis. METHODS: Advanced cirrhosis was induced by CCl(4 )inhalation and Phenobarbital administration for 30 weeks. Cirrhotic animals were divided into two groups which received IGF-I or saline during two weeks. Control group was studied in parallel. Jejunal microvilli were studied by electron microscopy. Nutrient transport was assessed in brush border membrane vesicles using (14)C or (35)S-labelled subtracts in the three experimental groups. RESULTS: Intestinal active Na(+)-dependent transport was significantly reduced in untreated cirrhotic rats. Kinetic studies showed a decreased V(max )and a reduced affinity for sugar and four amino acids transporters (expressed as an increased K(t)) in the brush border membrane vesicles from untreated cirrhotic rats as compared with controls. Both parameters were normalised in the IGF-I-treated cirrhotic group. Electron microscopy showed elongation and fusion of microvilli with degenerative membrane lesions and/or notable atrophy. CONCLUSIONS: The initial microvilli elongation reported in non ascitic cirrhosis develops into atrophy in rats with advanced cirrhosis and nutrient transports (monosaccharides and amino acids) are progressively reduced. Both morphological and functional alterations improved significantly with low doses of IGF-I
Models and metaphors: complexity theory and through-life management in the built environment
Complexity thinking may have both modelling and metaphorical applications in the through-life management of the built environment. These two distinct approaches are examined and compared. In the first instance, some of the sources of complexity in the design, construction and maintenance of the built environment are identified. The metaphorical use of complexity in management thinking and its application in the built environment are briefly examined. This is followed by an exploration of modelling techniques relevant to built environment concerns. Non-linear and complex mathematical techniques such as fuzzy logic, cellular automata and attractors, may be applicable to their analysis. Existing software tools are identified and examples of successful built environment applications of complexity modelling are given. Some issues that arise include the definition of phenomena in a mathematically usable way, the functionality of available software and the possibility of going beyond representational modelling. Further questions arising from the application of complexity thinking are discussed, including the possibilities for confusion that arise from the use of metaphor. The metaphor of a 'commentary machine' is suggested as a possible way forward and it is suggested that an appropriate linguistic analysis can in certain situations reduce perceived complexity
Fibre bundle formulation of nonrelativistic quantum mechanics: I. Introduction. The evolution transport
We propose a new systematic fibre bundle formulation of nonrelativistic
quantum mechanics. The new form of the theory is equivalent to the usual one
but it is in harmony with the modern trends in theoretical physics and
potentially admits new generalizations in different directions. In it a pure
state of some quantum system is described by a state section (along paths) of a
(Hilbert) fibre bundle. Its evolution is determined through the bundle
(analogue of the) Schr\"odinger equation. Now the dynamical variables and the
density operator are described via bundle morphisms (along paths). The
mentioned quantities are connected by a number of relations derived in this
work.
The present first part of this investigation is devoted to the introduction
of basic concepts on which the fibre bundle approach to quantum mechanics
rests. We show that the evolution of pure quantum-mechanical states can be
described as a suitable linear transport along paths, called evolution
transport, of the state sections in the Hilbert fibre bundle of states of a
considered quantum system.Comment: 26 standard (11pt, A4) LaTeX 2e pages. The packages AMS-LaTeX and
amsfonts are required. Revised: new material, references, and comments are
added. Minor style chages. Continuation of quan-ph/9803083. For continuation
of the this series see http://www.inrne.bas.bg/mathmod/bozhome
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