237 research outputs found
Minimizing the condition number of a positive definite matrix by completion
No full textElsner L, He C, Mehrmann V. Minimizing the condition number of a positive definite matrix by completion. Numerische Mathematik. 1994;69(1):17-23.We consider the problem of minimizing the spectral condition number of a positive definite matrix by completion: [GRAPHICS] where A is an n x n Hermitian positive definite matrix, B a p x n matrix and X is a free p x p Hermitian matrix. We reduce this problem to an optimization problem for a convex function in one variable. Using the minimal solution of this problem we characterize the complete set of matrices that give the minimum condition number
Proposal measures for the reactivation of industrial degraded areas in the case of the Zasavje statistical region
No full textV magistrskem delu smo se dotaknili problematike industrijskih degradiranih območij v Sloveniji. Sprva smo pregledali različne definicije degradiranega območja, tako tuje kot tudi slovenske. Pregledali in proučili smo slovenske in evropske iniciative na temo degradiranih območij in raziskali različna merila za določitev le teh. Sledil je pregled različnih ukrepov in strategij. Pregledali smo tudi številne primere dobrih praks prenove degradiranih industrijskih območij in poizkušali ugotoviti, na kakšen način so se lotili prenove. V magistrski nalogi smo v aplikativnem delu obravnavali Zasavsko statistično regijo, ki velja za najbolj degradirano regijo v Sloveniji. Regijo smo podrobno proučili in s pomočjo spletne aplikacije za vodenje evidence FDO poiskali industrijska degradirana območja v Zasavski regiji. Območja smo si ogledali na terenu in jih podrobno analizirali, izvedli smo tudi polstrukturiran intervju z nekaterimi lastniki zemljišč. Raziskava je pokazala, da je večina območij v lasti pravnih oseb, nekaj območij pa je v javni lasti. V zaključku naloge smo nato predlagali še ukrepe za reaktivacijo degradiranih industrijskih območij.In this master’s thesis the author discussed the problems of industrial degraded areas in Slovenia. The first task was to review various definitions of the degraded area, both foreign and Slovenian. The next step was to review and study Slovenian and European initiatives in degraded areas and investigate various criteria for determining degraded areas, which was followed by an overview of various measures and strategies. Several examples of good practice in the field of renovation of degraded industrial sites were examined, whereby the author tried to determine the renewal approach that was applied. In the empirical part of this thesis, issues in Zasavje statistical region, which is considered to be the most degraded region in Slovenia, were addressed. The region was examined in detail and industrial degraded areas in Zasavje region were determined by means of an online record-keeping application FDO (Functional degraded areas). The author has visited the examined areas, analysed them in detail, and conducted some semi-structured interviews with some landowners. The research has shown that the majority of the areas is owned by legal entities and that some areas are publicly owned. In the conclusion, the author suggested the measures that should be taken to reactivate degraded industrial sites
Relation of skewness factor and convection velocity in turbulent boundary layer
No full textThe paper is devoted to prove the relation between skewness factor and convection velocity in turbulent boundary layer. It appears that skewness factor can be used as an indicator of convection velocity of coherent structures, which is not always equal to the average flow velocity. The analysis has been performed based upon velocity profiles measured with hot-wire technique in turbulent boundary layer with pressure gradient corresponding to turbomachinery conditions. The results show that the cross product term of skewness factor decomposed by spectral filtering, which is also alternative measure of amplitude modulation, describes the convection velocity in zero pressure gradient turbulent boundary layer
Über Eigenwerteinschließungen mit Hilfe von Gerschgorin-Kreisen
No full textElsner L. Über Eigenwerteinschließungen mit Hilfe von Gerschgorin-Kreisen. Zeitschrift für angewandte Mathematik und Mechanik. 1970;50(6):381-384.Let the union of some Gerschgorin-disks of a matrix A be separated from the other disks by a circle of radius r and center Gamma. Medley and Varga have characterized the minimal r, which can be achieved by diagonal transformations of A and fixed Gamma. It is shown that this result can easily be proved with methods used in an earlier paper of the author. In addition, the maximal radius is characterized, easily computable bounds are given and it is shown, that A and the transposed matrix AT have the same optimal radii.Die Vereinigung gewisser Gerschgorin-Kreise einer Matrix A sei durch einen Kreis vom Radius r und Mittelpunkt Gamma von den übrigen Gerschgorin-Kreisen getrennt. Medley und Varga haben das minimale r, das bei festem Gamma durch Diagonaltransformationen von A erreicht werden kann, charakterisiert. Es wird gezeigt, daß dieses Ergebnis mit den in einer früheren Arbeit des Autors benutzten Methoden leicht bewiesen werden kann. Außerdem wird der maximale Radius charakterisiert, praktisch verwendbare Abschätzungen angegeben und gezeigt, daß A und die transponierte Matrix AT die gleichen optimalen Radien haben
Advanced hot rolling strategies for IF and TRIP steels
No full textSteel producers are forced to reduce the production cost on the one hand and increase the performances of the products on the other hand, to maintain or even increase their market share. A likely method to save on production costs is to cut down the rather long production chain for conventional cold rolled strip, and to substitute certain cold rolled steel grades by hot rolled steel. Certainly this can rarely be achieved for exposed parts, requiring a perfect surface finish, whereas for unexposed parts, e.g. structural components, with lower surface requirements, the use of hot strips might be a cost saving alternative. The aim of this thesis is to contribute to the understanding of the microstructure and texture development of deep-drawing steels during ferritic rolling, subsequent cold rolling and annealing on the one hand and to appraise the possible improvement of the mechanical and deep-drawing properties on the other hand. On the basis of these results guidelines for the industrial production of ferritic rolled hot strip are proposed. Furthermore, a new hot rolling strategy for the production of hot rolled low alloy TRIP steel is proposed and the development of the microstructure and the mechanical properties to be obtained are investigated in a set plain strain compression test using a hot deformation simulator.Aerospace Engineerin
Synthesis and investigation on the mode of action of 2,4,5-triaryl-2-imidazolines
No full textIn vorhergehenden Arbeiten konnten Imidazolinderivate mit interessanten
pharmakologischen Eigenschaften synthetisiert werden, insbesondere
(4R,5S)/(4S,5R)-2,4,5-Triaryl-2-imidazoline mit lipophilen Substituenten wie
Methyl, Methoxy oder Chlor an den Aromaten in Position 2, 4 und 5 des
Imidazolinringes. Diese Verbindungen weisen in Abhängigkeit vom
Substitutionsmuster ausgeprägt zytotoxische Wirkungen an Krebszellen auf. Ziel
dieser Arbeit war es neue Derivate der 2,4,5-Triaryl-2-imidazoline zu
entwickeln und diese hinsichtlich ihrer Struktur-Wirkungsbeziehung zu
analysieren. Die strukturellen Veränderungen wurden zum einen durch
N-Alkylierung und N,N'-Dialkylierung und zum anderen durch Änderung der
Konfiguration von (4R,5S)/(4S,5R) in (4R,5R)/(4S,5S) vorgenommen. Mit Hilfe
der Mikrowellentechnologie konnten Synthesemethoden entwickelt werden, die
schnell und effizient zu den angestrebten Zielstrukturen führten. Darüber
hinaus wurden (4R,5S)/(4S,5R)-2,4,5-Triaryl-2-imidazoline mit
stickstoffhaltigen Substituenten an den 2,4,5-positionierten Aromaten
erfolgreich synthetisiert. Die erzielten Verbindungen wurden auf ihre
zellulären Wirkungen getestet. Dazu wurde zuerst der Einfluss der
Strukturvariationen der 2,4,5-Triaryl-2-imidazoline auf die Hemmung der
Zellproliferation unter Verwendung der Tumorzelllinien: A549, MCF-7, MDA-
MB-231 und U2OS untersucht. Dabei stellten sich die N,N'-dipropylierten
2-Imidazoline als die Verbindungen mit den stärksten zytotoxischen
Eigenschaften von den im Rahmen dieser Arbeit synthetisierten und getesteten
Verbindungen heraus. Beispielsweise wurde für das
(4R,5S)/(4S,5R)-N,N'-Dipropyl-2,4,5-tris(4-ethylphenyl)-2-imidazoliniumiodid
an den MCF-7 Zellen ein IC50 Wert von 40 nmol/l ermittelt. Auch eine
N-Alkylierung der 2,4,5-Triaryl-2-imidazoline führt zu einer Steigerung der
Zytotoxizität. Die N-methyl- bzw. N-ethylierten 4-Chlor- und 4-Nitro-
substituierten 2-Imidazoline erfuhren eine drastische Abschwächung der
zytotoxischen Eigenschaften. Mit zunehmender Länge der N-Alkylkette und der
damit verbundenen Erhöhung der Lipophilie nehmen die IC50 Werte im Allgemeinen
deutlich ab. Die (4R,5S)/(4S,5R)-2,4,5-Triaryl-2-imidazoline mit
stickstoffhaltigem Substitutionsmuster an den Aromaten weisen deutlich höhere
IC50 Werte auf als die lipophileren Verbindungen. Ausgeprägte Unterschiede
zwischen den (4R,5S)/(4S,5R)- und (4R,5R)/(4S,5S)-konfigurierten Verbindungen
konnten nicht festgestellt werden. In weiterführenden biochemischen
Untersuchungen wurden die hoch zytotoxisch wirkenden Verbindungen auf ihre
Apoptose induzierenden Eigenschaften getestet. So konnten beispielsweise für
die N,N'-Dimethyl-2,4,5-tris(4-ethylphenyl)-2-imidazoliniumiodide sowohl eine
Caspase-3-Aktivität von etwa 2.5 als auch ein positiver Nachweis von ssDNA (Fx
= 6.5-8.1) beobachtet werden. Für die dazugehörigen einfach alkylierten
Verbindungen wurde lediglich Einzelstrang-DNA nachgewiesen (Fx = 7.5-7.9).
Aufgrund der strukturellen Ähnlichkeit der 2,4,5-Triaryl-2-imidazoline mit
Nutlin-3a wurde mit Hilfe eines zellulären Hdm2- und p53-Assays eine mögliche
Inhibition des Hdm2-Proteins und dem damit verbundenen p53-vermittelten
Zelltod untersucht. Die immunhistochemische Quantifizierung von p53 und Hdm2
ergab für die N-alkylierten und N,N'-dialkylierten
(4R,5S)/(4S,5R)-2,4,5-Triaryl-2-imidazoline keine durch p53 initiierte
Apoptose. Eine Hemmung von Hdm2 kann für das
(4R,5S)/(4S,5R)-2,4,5-Tris(4-chlorphenyl)-2-imidazolin diskutiert werden, da
in den Tumorzellen eine höhere Konzentration an Hdm2 als an p53 gefunden
wurde. Des Weiteren stellte sich für die untersuchten
(4R,5R)/(4S,5S)-2,4,5-Triaryl-2-imidazoline heraus, dass die Verbindungen
weder in alkylierter noch in nicht alkylierter Form in der Lage sind p53 zu
aktivieren. Die Testergebnisse der bisherigen Apoptose-Untersuchungen haben
gezeigt, dass die 2,4,5 Triaryl-2 imidazoline durchaus in der Lage sind den
programmierten Zelltod auszulösen. Dennoch scheint die Apoptose nicht über den
p53-vermittelten Signalweg und in der ausführenden Phase nicht vornehmlich
über die Effektorcaspase-3 zu verlaufen. Es sind daher zwingend weitere
Untersuchungen nötig, um den Wirkungsmechanismus der äußerst potenten
N-alkylierten und N,N'-dialkylierten 2,4,5-Triaryl-2-imidazoline aufzuklären.In previous works several imidazoline derivatives with very interesting
pharmacological properties were synthesized, i.e.
(4R,5S)/(4S,5R)-2,4,5-triaryl-2-imidazolines with lipophilic substituents such
as chlorine, methyl or methoxy groups in position 2, 4 and 5 of the aromatic
moieties. Depending on their substitution pattern these compounds showed
cytotoxic effects on cancer cells. The aim of this work was to develop new
2,4,5-triaryl-2-imidazolines and to analyze their structure activity
relationship in terms of cytotoxicity. On the one hand structural changes were
made by N-alkylation or N,N'-dialkylation and on the other hand compounds with
either (4R,5S)/(4S,5R)- or (4R,5R)/(4S,5S)-configuration. Various
(4R,5S)/(4S,5R)-2,4,5-triaryl-2-imidazolines with nitro-genous substituents in
position 2, 4 and 5 of aromatic moieties were successfully synthesized too.
Using microwave technology, synthetic methods were developed allowing a fast
and efficient synthesis of the above mentioned compounds. The compounds were
analyzed in terms of their cellular effects using different established in-
vitro assays. Initially, the inhibiting effect on cell proliferation was
investigated using the tumor cell lines A549, MCF-7, MDA-MB-231 and U2OS. In
this context the highest cytotoxicity was observed for
N,N'-dipropyl-2-imidazolines, i.e.
(4R,5S)/(4S,5R)-N,N'-dipropyl-2,4,5-tris-(4-ethylphenyl)-2-imidazoliniumiodide
which exhibited an IC50 value of 40 nmol/l on MCF-7 cells. N-alkylation of
2,4,5-triaryl-2-imidazolines led to an increase in cytotoxicity whereas
N-methylation or N-ethylation of 4-chlor- and 4-nitro-substituted
2-imidazolines led to a drastic attenuation of the cytotoxic properties. The
elongation of alkyl chain and the associated increase in lipophilicity were
generally accompanied by a significant decrease of IC50 values.
(4R,5S)/(4S,5R)-2,4,5-triaryl-2-imidazolines with nitrogen residues in
position 2, 4 and 5 of the aromatic moieties appeared to be less cytotoxic. A
change from (4R,5S)/(4S,5R)- to (4R,5R)/(4S,5S)-configuration did not effect
cytotoxicity. In further studies the most promising cytotoxic compounds were
investigated in terms of their apoptosis-inducing properties. For
N,N'-Dimethyl-2,4,5-tris-(4-ethylphenyl)-2-imidazoliniumiodides caspase-3
activity of about 2.5 and positive detection of ssDNA (Fx = 6.5-8.1) were
observed whereas for the corresponding monoalkylated compounds single-stranded
DNA (Fx = 7.5-7.9) but no caspase-3 activity was found. Due to the structural
similarity of the 2,4,5-triaryl-2-imidazolines to nutlin-3a a possible
inhibition of hdm2 protein and associated p53 induced cell death were noticed.
Immunohistochemical quantification of p53 and hdm2 did not exhibit p53 induced
apoptosis for N-alkylated as well as for N,N'-dialkylated
(4R,5S)/(4S,5R)-2,4,5-triaryl-2-imidazolines. Interestingly, in A549 cells a
higher concentration of hdm2 compared to p53 was found for
(4R,5S)/(4S,5R)-2,4,5-tris-(4-chlorphenyl)-2-imidazoline which might indicate
hdm2 inhibiting properties. For all investigated compounds with
(4R,5R)/(4S,5S)-configuration no p53 activating effect was observed. Although
the results of the apoptosis tests have demonstrated that
2,4,5-triaryl-2-imidazolines are able to trigger programmed cell death it
appeared that this process was neither p53 induced nor associated with
caspase-3 in the executive phase. Therefore further studies are necessary to
elucidate the mechanism of action of the N-alkylated and N,N'-dialkylated
2,4,5-triaryl-2-imidazolines
Abstinence of Former Pervitin Users
No full textBakalářská práce je zaměřena na problematiku drogové závislosti. Autorka přibližuje historii, druhy, příčiny a průběh vzniku závislosti. Poukazuje na potřebu prevence vzniku drogové závislosti. Také se zabývá možnostmi léčby a vymezuje roli sociálního pracovníka. V praktické části se autorka zaměřuje na abstinenci od pervitinu a riziko recidivy. Výzkum je realizován kvalitativní metodou prostřednictvím polostrukturovaných rozhovorů s bývalými pacienty psychiatrické nemocnice s diagnózou závislosti na pervitinuThe bachelor work is focused on the issue of drug dependence. The author describes the history, classification, causes and origins of dependence. She points to the need for prevention of drug dependence. The work also deals with the possibilities of healing and defines the role of social worker. In the practical part, the author focuses on pervitin abstinence and the risk of relapse. The research is carried out by qualitative method of semi-structured interviews with former patients of Psychiatric Hospital with pervitin dependence diagnosis.Ústav zdravotnických vě
Convex combinations of matrices — Full rank characterization
No full textAbstractLet A1,…, Ak be complex n-by-m matrices. Using the notion of a block P-matrix, introduced recently by Elsner and the second author, a characterization of the full rank property of all convex combinations of A1,…, Ak is derived
Symmetric schemes for computing the minimum eigenvalue of a symmetric Toeplitz matrix
No full textde Dedicated to Ludwig Elsner on the occasion of his th birthday In and W Mackens and the present author presented two generaliza tions of a method of Cybenko and Van Loan for computing the smallest eigenvalue of a symmetric positive de nite Toeplitz matrix Taking advan tage of the symmetry or skew symmetry of the corresponding eigenvector both methods are improved considerabl
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