Physical principles underlying the quantum Hall effect

In this contribution, we present an introduction to the physical principles underlying the quantum Hall effect. The field theoretic approach to the integral and fractional effect is sketched, with some emphasis on the mechanism of electromagnetic gauge anomaly cancellation by chiral degrees of freedom living on the edge of the sample. Applications of this formalism to the design and theoretical interpretation of interference experiments are outlined.Comment: 20 pages, 8 figures; small corrections, replaced with published versio

Gauge-invariant charged, monopole and dyon fields in gauge theories

We propose explicit recipes to construct the euclidean Green functions of gauge-invariant charged, monopole and dyon fields in four-dimensional gauge theories whose phase diagram contains phases with deconfined electric and/or magnetic charges. In theories with only either abelian electric or magnetic charges, our construction is an euclidean version of Dirac's original proposal, the magnetic dual of his proposal, respectively. Rigorous mathematical control is achieved for a class of abelian lattice theories. In theories where electric and magnetic charges coexist, our construction of Green functions of electrically or magnetically charged fields involves taking an average over Mandelstam strings or the dual magnetic flux tubes, in accordance with Dirac's flux quantization condition. We apply our construction to 't Hooft-Polyakov monopoles and Julia-Zee dyons. Connections between our construction and the semiclassical approach are discussed

Blow-Up for Nonlinear Wave Equations describing Boson Stars

We consider the nonlinear wave equation $i \partial_t u= \sqrt{-\Delta + m^2} u - (|x|^{-1} \ast |u|^2) u$ on \RR^3 modelling the dynamics of (pseudo-relativistic) boson stars. For spherically symmetric initial data, u_0(x) \in C^\infty_{\mathrm{c}}(\RR^3), with negative energy, we prove blow-up of $u(t,x)$ in $H^{1/2}$-norm within a finite time. Physically, this phenomenon describes the onset of "gravitational collapse" of a boson star. We also study blow-up in external, spherically symmetric potentials and we consider more general Hartree-type nonlinearities. As an application, we exhibit instability for ground state solitary waves at rest if $m=0$.Comment: final version; to appear in Comm. Pure Appl. Math; 14 page

On systematic approaches for interpreted information transfer of inspection data from bridge models to structural analysis

In conjunction with the improved methods of monitoring damage and degradation processes, the interest in reliability assessment of reinforced concrete bridges is increasing in recent years. Automated imagebased inspections of the structural surface provide valuable data to extract quantitative information about deteriorations, such as crack patterns. However, the knowledge gain results from processing this information in a structural context, i.e. relating the damage artifacts to building components. This way, transformation to structural analysis is enabled. This approach sets two further requirements: availability of structural bridge information and a standardized storage for interoperability with subsequent analysis tools. Since the involved large datasets are only efficiently processed in an automated manner, the implementation of the complete workflow from damage and building data to structural analysis is targeted in this work. First, domain concepts are derived from the back-end tasks: structural analysis, damage modeling, and life-cycle assessment. The common interoperability format, the Industry Foundation Class (IFC), and processes in these domains are further assessed. The need for usercontrolled interpretation steps is identified and the developed prototype thus allows interaction at subsequent model stages. The latter has the advantage that interpretation steps can be individually separated into either a structural analysis or a damage information model or a combination of both. This approach to damage information processing from the perspective of structural analysis is then validated in different case studies

"Needless to Say My Proposal Was Turned Down": The Early Days of Commercial Citation Indexing, an "Error-making" Activity and Its Repercussions Till Today

In today’s neoliberal audit cultures university rankings, quantitative evaluation of publications by JIF or researchers by h-index are believed to be indispensable instruments for “quality assurance” in the sciences. Yet there is increasing resistance against “impactitis” and “evaluitis”. Usually overseen: Trivial errors in Thomson Reuters’ citation indexes produce severe non-trivial effects: Their victims are authors, institutions, journals with names beyond the ASCII-code and scholars of humanities and social sciences. Analysing the “Joshua Lederberg Papers” I want to illuminate eventually successful ‘invention’ of science citation indexing is a product of contingent factors. To overcome severe resistance Eugene Garfield, the “father” of citation indexing, had to foster overoptimistic attitudes and to downplay the severe problems connected to global and multidisciplinary citation indexing. The difficulties to handle different formats of references and footnotes, non-Anglo-American names, and of publications in non-English languages were known to the pioneers of citation indexing. Nowadays the huge for-profit North-American media corporation Thomson Reuters is the owner of the citation databases founded by Garfield. Thomson Reuters’ influence on funding decisions, individual careers, departments, universities, disciplines and countries is immense and ambivalent. Huge technological systems show a heavy inertness. This insight of technology studies is applicable to the large citation indexes by Thomson Reuters, too

Absence of Embedded Mass Shells: Cerenkov Radiation and Quantum Friction

We show that, in a model where a non-relativistic particle is coupled to a quantized relativistic scalar Bose field, the embedded mass shell of the particle dissolves in the continuum when the interaction is turned on, provided the coupling constant is sufficiently small. More precisely, under the assumption that the fiber eigenvectors corresponding to the putative mass shell are differentiable as functions of the total momentum of the system, we show that a mass shell could exist only at a strictly positive distance from the unperturbed embedded mass shell near the boundary of the energy-momentum spectrum.Comment: Revised version: a remark added at the end of Section

Housing policy and economic development: the Croatian case

Housing in Croatia is beset with many problems, as reflected in a dramatic fall in new housing construction, low housing standards, absence of streamlined policy which would encourage housing construction, as well as ambiguous regulations governing this area. Transition from planned to market economy requires far-reaching and comprehensive changes in the whole institutional framework, from central government structures to the private sector. This is particularly true of the housing sector which under the previous socio-economic system had a special political and social place. Transformation and introduction of new institutional structures required for a successful development of the housing sector in Croatia is one of the main bottlenecks within that sector. This particularly applies to local authorities, non-profit housing associations and the private sector. However, what is still missing is the main leverage required for organising the housing activities at the national level - and these are appropriate financial instruments, in the sense that they are not developed enough to enable the housing sector to really contribute to Croatia's economic and social development. To be more specific, it is necessary to provide financial instruments and paper will deal with proposals for the national housing finance policy. Namely, what will be checked too, is a gradual shift of general state support mechanisms towards direct public financing of priority projects, for example, in the form of subsidies. Subsidy financing would be efficiently concentrated on the housing projects enjoying a general public and political priority, such as low-cost housing construction for young families/first-time homebuyers or social housing projects of local authorities or projects of non-profit housing associations based on rental and controlled prices of new housing units. In the future restructuring of local administration and self-government units allowance will have to be made for the need to clearly define responsibilities in order to ensure efficiency in implementing the housing policies. This topic will be particularly emphasized in the paper as well as the role of non-profit housing associations and banking sector. At the end will be presented an outline of the key elements of the housing sector in Croatia as seen by the Expert Group to highlight the main bottlenecks in the sector and to propose the future actions of the national housing strategy.

Thermal Ionization

In the context of an idealized model describing an atom coupled to black-body radiation at a sufficiently high positive temperature, we show that the atom will end up being ionized in the limit of large times. Mathematically, this is translated into the statement that the coupled system does not have any time-translation invariant state of positive (asymptotic) temperature, and that the expectation value of an arbitrary finite-dimensional projection in an arbitrary initial state of positive (asymptotic) temperature tends to zero, as time tends to infinity. These results are formulated within the general framework of $W^*$-dynamical systems, and the proofs are based on Mourre's theory of positive commutators and a new virial theorem. Results on the so-called standard form of a von Neumann algebra play an important role in our analysis