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Search Results: 1 - 10 of 151 matches for " Sokol Ndreca "
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A continuum limit for the Kronig-Penney model
Matteo Colangeli,Sokol Ndreca,Aldo Procacci
Physics , 2014,
Abstract: We investigate the transmission properties of a quantum one-dimensional periodic system of fixed length $L$, with $N$ barriers of constant height $V$ and width $\lambda$, and $N$ wells of width $\delta$. In particular, we study the behaviour of the transmission coefficient in the limit $N\to \infty$, with $L$ fixed. This is achieved by letting $\delta$ and $\lambda$ both scale as $1/N$, in such a way that their ratio $\gamma= \lambda/\delta$ is a fixed parameter characterizing the model. In this continuum limit the multi-barrier system behaves as it were constituted by a unique barrier of constant height $E_o=(\gamma V)/(1+\gamma)$. The analysis of the dispersion relation of the model shows the presence of forbidden energy bands at any finite $N$.
Improved bounds on coloring of graphs
Sokol Ndreca,Aldo Procacci,Benedetto Scoppola
Mathematics , 2010,
Abstract: Given a graph $G$ with maximum degree $\Delta\ge 3$, we prove that the acyclic edge chromatic number $a'(G)$ of $G$ is such that $a'(G)\le\lceil 9.62 (\Delta-1)\rceil$. Moreover we prove that: $a'(G)\le \lceil 6.42(\Delta-1)\rceil$ if $G$ has girth $g\ge 5\,$; $a'(G)\le \lceil5.77 (\Delta-1)\rc$ if $G$ has girth $g\ge 7$; $a'(G)\le \lc4.52(\D-1)\rc$ if $g\ge 53$; $a'(G)\le \D+2\,$ if $g\ge \lceil25.84\D\log\D(1+ 4.1/\log\D)\rceil$. We further prove that the acyclic (vertex) chromatic number $a(G)$ of $G$ is such that $a(G)\le \lc 6.59 \Delta^{4/3}+3.3\D\rc$. We also prove that the star-chromatic number $\chi_s(G)$ of $G$ is such that $\chi_s(G)\le \lc4.34\Delta^{3/2}+ 1.5\D\rc$. We finally prove that the $\b$-frugal chromatic number $\chi^\b(G)$ of $G$ is such that $\chi^\b(G)\le \lc\max\{k_1(\b)\D,\; k_2(\b){\D^{1+1/\b}/ (\b!)^{1/\b}}\}\rc$, where $k_1(\b)$ and $k_2(\b)$ are decreasing functions of $\b$ such that $k_1(\b)\in[4, 6]$ and $k_2(\b)\in[2,5]$. To obtain these results we use an improved version of the Lov\'asz Local Lemma due to Bissacot, Fern\'andez, Procacci and Scoppola \cite{BFPS}.
A-priori Upper Bounds for the Set Covering Problem
Giovanni Felici,Sokol Ndreca,Aldo Procacci,Benedetto Scoppola
Mathematics , 2014,
Abstract: In this paper we present a new bound obtained with the probabilistic method for the solution of the Set Covering problem with unit costs. The bound is valid for problems of fixed dimension, thus extending previous similar asymptotic results, and it depends only on the number of rows of the coefficient matrix and the row densities. We also consider the particular case of matrices that are \textit{almost} block decomposable, and show how the bound may improve according to the particular decomposition adopted. Such final result may provide interesting indications for comparing different matrix decomposition strategies.
Advances on the Late Arrivals Problem
Carlo Lancia,Gianluca Guadagni,Sokol Ndreca,Benedetto Scoppola
Mathematics , 2013,
Abstract: We study a discrete time queueing system where deterministic arrivals have i.i.d. exponential delays $\xi_{i}$. The standard deviation $\sigma$ of the delay is finite, but its value is much larger than the deterministic unit service time. We describe the model as a bivariate Markov chain and focus on the joint equilibrium distribution. We also prove that the latter decays super-exponentially fast in the quarter plane. Finally, we discuss the numerical computation of the stationary distribution, showing the effectiveness of a simple approximation scheme in a wide region of the parameters. The model, motivated by air and railway traffic, was proposed many decades ago by Kendall with the name of "late arrivals problem", but no solution has been found so far.
Use of Dorsal Metacarpal Artery Flaps in Post Burn Reconstruction - Two Cases Report
Sokol Isaraj
Macedonian Journal of Medical Sciences , 2011, DOI: 10.3889/MJMS.1857-5773.2011.0164
Abstract: Perforator flaps based on the dorsal metacarpal arteries, islanded on a reverse flow pattern are used for reconstruction of two patients respectively with an unstable scar located on the MCP joints and a severe contracture of the ring finger, with full survival and excellent long term results.
Use of Dorsal Metacarpal Artery Flaps in Post Burn Reconstruction – Two Cases Report
Sokol Isaraj
Macedonian Journal of Medical Sciences , 2011,
Abstract: Perforator flaps based on the dorsal metacarpal arteries, islanded on a reverse flow pattern are used for reconstruction of two patients respectively with an unstable scar located on the MCP joints and a severe contracture of the ring finger, with full survival and excellent long term results.
A TECHNOLOGY PARK AS AN INSTITUTION THAT SUPPORTS TRANSFER OF INNOVATION AND KNOWLEDGE TO THE SME SECTOR COMPANIES
ANETA SOKOL
Perspectives of Innovations, Economics and Business , 2011,
Abstract: Application of advanced technologies in small and medium-sized enterprises allows them to gain a competitive advantage on the market. New technologies are developed by research laboratories, R&D (research and development) laboratories of companies, as well as by public scientific centers. The key issue is cooperation between the academic world and entrepreneurs, which should be aimed mainly at transfer of innovation. The function of technology transfer is played, among other institutions, by technology parks. The objective of this article is to present some of the problems associated with taking advantage of the potential of technology parks for entrepreneurs in the area of research and development.
Research into development potentialities of academic entrepreneurship in Poland
Aneta Sokol
Perspectives of Innovations, Economics and Business , 2010,
Abstract: The issue of academic entrepreneurship is becoming a more and more fashionable topic which functions on the research and business cooperation plane at the institutional level and business incubators supporting private ventures of students and research personnel. The interactions of universities with economy, business use of research projects results as well as the transfer of innovations and technologies are becoming the basis for the government’s strategy at the central, local, university management level and the object of activities for numerous organizations. Considering this context, the article discusses development potentialities of academic entrepreneurship in Poland.
Vocational Guidance as a Tool Against the Abandonment of the University.
Sokol Pacukaj
Mediterranean Journal of Social Sciences , 2010,
Abstract: One of the most important choices of students in their lives is undoubtedly the choice of the university they want to attend. The orientation of young people is a strategic resource which is expressed in many activities that in turn aims at training and enhancing the ability of students to know themselves, the living environment, socio-economic and cultural changes, deals training, being protagonists of a personal life project and participate in the study, family and social life in an active, equal and responsible way.Improper orientation brings with it serious consequences for those who have less support, especially in cases of expulsion from educational system. In their choice of university courses is good to avoid referring only to return to school or especially concentrating on grades in academic subjects. It should expand the vision to discover the tendencies and the vocation of the person, and then his/her desire to face challenges ahead.
Diverse Voices: Czech Women’s Writing in the Post-Communist Era
Elena SOKOL
Argument : Biannual Philosophical Journal , 2012,
Abstract: This essay offers an overview of the diversity of women’s prose writing that emerged on the Czech cultural scene in the post-communist era. To that end it briefly characterizes the work of eight Czech women authors who were born within the first two decades after World War II and began to create during the post-1968 era of ‘normalization’. In this broad sense they belong to a single generation. With rare exception their work was not officially published in their homeland until the 1990s. The writers included are: Lenka Procházková, Tereza Bou ková, Alexandra Berková, Zuzana Brabcová, Daniela Hodrová, Sylvie Richterová, Iva Pekárková, and Eva Hauserová. The overview is followed by a concise comparative analysis of texts by three very different writers (Procházková, Pekárková, and Hodrová), using a feminist critical approach. There is also an appendix of works by these writers available in English translation.
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