Paradoxes of measures of quantum entanglement and Bell's inequality violation in two-qubit systems

We review some counterintuitive properties of standard measures describing quantum entanglement and violation of Bell's inequality (often referred to as "nonlocality") in two-qubit systems. By comparing the nonlocality, negativity, concurrence, and relative entropy of entanglement, we show: (i) ambiguity in ordering states with the entanglement measures, (ii) ambiguity of robustness of entanglement in lossy systems and (iii) existence of two-qubit mixed states more entangled than pure states having the same negativity or nonlocality. To support our conclusions, we performed a Monte Carlo simulation of $10^6$ two-qubit states and calculated all the entanglement measures for them. Our demonstration of the relativity of entanglement measures implies also how desirable is to properly use an operationally-defined entanglement measure rather than to apply formally-defined standard measures. In fact, the problem of estimating the degree of entanglement of a bipartite system cannot be analyzed separately from the measurement process that changes the system and from the intended application of the generated entanglement.Comment: 10 pages, 4 figures, to appear in the Journal of Computational Methods in Sciences and Engineering -- a special issue in memory of prof. S. Kielic

Gun Enforcement and Gun Violence Prevention Practices among Local Law Enforcement Agencies: A Research and Policy Brief

Controlling gun crime continues to be a difficult challenge for policymakers and practitioners in the United States. In 2009, there were roughly 11,000 murders with firearms in the United State and another 326,000 non-fatal violent crimes with guns . The prevalence of guns is thought to contribute to particularly high levels of homicide in the United States, where some estimates imply that the total costs of gun violence -- including medical, criminal justice, and other costs -- could be well over $100 billion per year.Yet finding common ground for legislative solutions to this problem is quite difficult, making it especially critical to effectively enforce existing laws and utilize other prevention approaches. Indeed, debates on controlling firearms violence often revolve around whether the nation needs tougher gun laws or better enforcement of laws that already exist. However, these debates are not well informed by systematic information on what law enforcement agencies are doing to reduce gun violence, the success of those efforts, and the factors that facilitate or hinder those efforts. In order to inform debate on these issues and to highlight successful enforcement and prevention strategies to reduce gun violence, the Police Executive Research Forum (PERF) undertook a national study of gun violence prevention efforts by local police in urban jurisdictions. The study's objectives were to: 1) to describe the range, scope, and prevalence of police efforts to reduce gun violence; 2) to assess which practices are most effective, both generally and in combination with different gun laws; and 3) to determine how these efforts can be improved

Building communities for the exchange of learning objects: theoretical foundations and requirements

In order to reduce overall costs of developing high-quality digital courses (including both the content, and the learning and teaching activities), the exchange of learning objects has been recognized as a promising solution. This article makes an inventory of the issues involved in the exchange of learning objects within a community. It explores some basic theories, models and specifications and provides a theoretical framework containing the functional and non-functional requirements to establish an exchange system in the educational field. Three levels of requirements are discussed. First, the non-functional requirements that deal with the technical conditions to make learning objects interoperable. Second, some basic use cases (activities) are identified that must be facilitated to enable the technical exchange of learning objects, e.g. searching and adapting the objects. Third, some basic use cases are identified that are required to establish the exchange of learning objects in a community, e.g. policy management, information and training. The implications of this framework are then discussed, including recommendations concerning the identification of reward systems, role changes and evaluation instruments

GRANICE OCHRONY TAJEMNICY DZIENNIKARSKIEJ W PROCESIE KARNYM

The paper is an attempt to delineate model boundaries of protection of journalist secrecy when it comes to criminal proceedings. Despite the existing protection available under media law which also affects the criminal trial, certain modifications are still necessary. The paper discuses events when a journalist must be released from the duty of secrecy in the course of criminal proceedings. The existing normative regulations have been analysed, their defects identified, and certain improvements and amendments proposed. The controversial issue of the actual waiver of journalist secrecy has also been examined. The general goal of the paper is to postulate creation of solutions that will result from proper decisions made when the concurrent interests and values clash.Artykuł stanowi próbę zakreślenia modelowych granic ochrony tajemnicy dziennikarskiej w relacji do postępowania karnego. Wprawdzie ogólny zakres tej ochrony, wyznaczony przepisami Prawa prasowego, oddziałuje także na proces karny, niemniej jednak musi w ramach tej procedury doznać pewnej modyfikacji, co jest konsekwencją rangi i znaczenia postępowania prowadzonego na podstawie przepisów Kodeksu postępowania karnego. W opracowaniu omówiono zatem wypadki, w których zachodzi potrzeba zwolnienia dziennikarza z obowiązku przestrzegania tajemnicy dziennikarskiej w związku z prowadzonym postępowaniem karnym. Dokonano oceny istniejących regulacji normatywnych, wskazano ich mankamenty, a w rezultacie zaproponowano uzupełnienie lub zmianę obowiązujących przepisów. Analizie poddano także bardzo niejednoznaczny i kontrowersyjny problem dotyczący faktycznego uchylenia tajemnicy dziennikarskiej. Całość rozważań ujętych w opracowaniu jest podporządkowana postulatowi kreowania takich rozwiązań, które są wynikiem właściwego rozstrzygnięcia kolizji zbiegających się dóbr i wartości

«Ciało» na wojnie. Wokół Soli ziemi Józefa Wittlina

The article introduces methodology of cultural studies depicting the soldier’s body in Józef Wittlin’s novel Sól ziemi (The Salt of the Earth). Texts about the novel and articles from other scientific disciplines (for example history, philosophy, medicine) allow to draw a wide context of interpretation. They show that changes in the perception of a body depend on scientific progress and industrialization. World War I allows Wittlin to reveal the ambiguous progress of medical science which can cure crippled bodies, but at the same time it requires the very same war to evolve. The literary reflection and discourses of natural and social sciences help us to understand changes that happened in Europe in the 20th century and to notice their present repercussions.Artykuł przybliża metodologię badań kulturowych na przykładzie analizy obrazowania ciała żołnierza w powieści Józefa Wittlina Sól ziemi. Teksty wokół powieści oraz artykuły z innych dyscyplin (historia, filozofia, medycyna) pozwalają nakreślić szeroki kontekst interpretacyjny. Pokazują, że zmiany w postrzeganiu ciała wiążą się z postępem nauki i industrializacją. Odczytanie powieści z perspektywy badań kulturowych pozwala ujawnić niejednoznaczność postępu nauk medycznych, które potrafią naprawiać okaleczone ciała żołnierzy, jednocześnie przyczyniając się do rozwoju okrutnych metod walk. Refleksja literacka razem z dyskursami nauk przyrodniczych i społecznych pozwala zrozumieć przemiany, jakie dokonały się w Europie w XX wieku, i dostrzec ich skutki we współczesności

Zum Problem der Selbst- und Fremdpositionierung in Vladimir Vertlibs Roman „Viktor hilft”

Mit dem Roman Viktor hilft (2018) bestätigt Vladimir Vertlib mehrfach seine literarische Verortung: sein Meta-Narrativ bleibt nach wie vor eine kulturanthropologisch fokussierte Migrations-erfahrung. Diese impliziert eine punktuelle Erfahrung der Zeitgenossenschaft und der Zeugenschaft und in eben diesem Zusammenhang wird untersucht, wie sich die Erzählinstanz im Text selbst- und fremdpositioniert, wozu das sozio-linguistische Konzept der Positionierung von Wendy Hollowey wichtige Impulse liefert (Hollowey 1984). Bei der Annahme des autobiographischen Ansatzes des Romans wird am Beispiel von Viktor Levin als Alter Ego Vertlibs die Positionierung eines hybriden Subjekts in Literatur und Leben eruiert, gemäß der These: Aufgrund der Selbst- und Fremdpositionierung der Erzählinstanz im Roman Viktor hilft ist Vladimir Vertlib als Autor mit einem „hybriden- kulturellen Hintergrund“ (Previsič 2012: 50) und damit als ein exophoner Autor im „Dritten Raum“ (Bhabha 1994/2000) zu verorten.By his novel Viktor hilft (2018), Vladimir Vertlib definitely confirms his place in literature: his meta-narrative invariably constitutes the experience of migration perceived in cultural and anthropological way. It implies a specific, individual experience of the presence and giving the testimony. In this context, it is essential to examine, making use of Wendy Hollowey’s socio-linguistic concept of positioning (Hollowey 1984), how the narrator presents himself and the others in the text. Assuming that the book has some autobiographical features, the Viktor Levin’s character is being analysed as Viktor Vertlib’s alter ego in order to examine how the hybrid like subject places himself and the others in the literature and life. The analysis of Viktor hilft is carried out as a narrator’s selfpresentation and presentation of other characters, which allows you to confirm the thesis that the place of Vladimir Vertlib as a writer with “hybrid culture experience” (Previsič 2012: 50) and as an exophonic writer is the “Third Space” (Bhabha 1994/2000)

Incomplete approach to homoclinicity in a model with bent-slow manifold geometry

The dynamics of a model, originally proposed for a type of instability in plastic flow, has been investigated in detail. The bifurcation portrait of the system in two physically relevant parameters exhibits a rich variety of dynamical behaviour, including period bubbling and period adding or Farey sequences. The complex bifurcation sequences, characterized by Mixed Mode Oscillations, exhibit partial features of Shilnikov and Gavrilov-Shilnikov scenario. Utilizing the fact that the model has disparate time scales of dynamics, we explain the origin of the relaxation oscillations using the geometrical structure of the bent-slow manifold. Based on a local analysis, we calculate the maximum number of small amplitude oscillations, $s$, in the periodic orbit of $L^s$ type, for a given value of the control parameter. This further leads to a scaling relation for the small amplitude oscillations. The incomplete approach to homoclinicity is shown to be a result of the finite rate of `softening' of the eigen values of the saddle focus fixed point. The latter is a consequence of the physically relevant constraint of the system which translates into the occurrence of back-to-back Hopf bifurcation.Comment: 14 Figures(Postscript); To Appear in Physica D : Nonlinear Phenomen

Anomalous diffusion of a particle in an aging medium

We report new results about the anomalous diffusion of a particle in an aging medium. For each given age, the quasi-stationary particle velocity is governed by a generalized Langevin equation with a frequency-dependent friction coefficient proportional to $|\omega|^{\delta-1}$ at small frequencies, with $0<\delta<2$. The aging properties of the medium are encoded in a frequency dependent effective temperature $T_{\rm eff.}(\omega)$. The latter is modelized by a function proportional to $|\omega|^\alpha$ at small frequencies, with $\alpha<0$, thus allowing for the medium to have a density of slow modes proportionally larger than in a thermal bath. Using asymptotic Fourier analysis, we obtain the behaviour at large times of the velocity correlation function and of the mean square displacement. As a result, the anomalous diffusion exponent in the aging medium appears to be linked, not only to $\delta$ as it would be the case in a thermal bath, but also to the exponent $\alpha$ characterizing the density of slow modes

Learning Design: reflections on a snapshot of the current landscape

The mounting wealth of open and readily available information and the swift evolution of social, mobile and creative technologies warrant a re-conceptualisation of the role of educators: from providers of knowledge to designers of learning. This need is being addressed by a growing trend of research in Learning Design. Responding to this trend, the Art and Science of Learning Design workshop brought together leading voices in the field and provided a forum for discussing its key issues. It focused on three thematic axes: practices and methods, tools and resources, and theoretical frameworks. This paper reviews some definitions of Learning Design and then summarises the main contributions to the workshop. Drawing upon these, we identify three key challenges for Learning Design that suggest directions for future research

Recursive algorithms for the elimination of redundant paths in spatial lag operators

Recursive algorithms for the elimination of redundant paths in spatial lag operators are introduced. It is shown that these algorithms have superior computational properties in comparison with the cumbersome procedure proposed by Ross and Harary (1952). A rigorous definition of spatial lag operators is given, while a number of mathematical results and properties are derived. Theoretical and empirical results regarding the performance of the proposed algorithms are presented