Exact Ground-State Energy of the Ising Spin Glass on Strips

We propose a new method for exact analytical calculation of the ground-state energy of the Ising spin glass on strips. An outstanding advantage of this method over the numerical transfer matrix technique is that the energy is obtained for complex values of the probability describing quenched randomness. We study the $\pm J$ and the site-random models using this method for strips of various sizes up to $5\times\infty$. The ground-state energy of these models is found to have singular points in the complex-probability plane, reminiscent of Lee-Yang zeros in the complex-field plane for the Ising ferromagnet. The $\pm J$ Ising model has a series of singularities which may approach a limiting point around $p \sim 0.9$ on the real axis in the limit of infinite width.Comment: 10 pages, 12 Postscript figures, LaTeX, uses subeqn.sty, minor changes in tex-fil

An HST/COS legacy survey of intervening SiIII absorption in the extended gaseous halos of low-redshift galaxies

Doubly ionized silicon (SiIII) is a powerful tracer of diffuse ionized gas inside and outside of galaxies. It can be observed in the local Universe in ultraviolet (UV) absorption against bright extragalactic background sources. We here present an extensive study of intervening SiIII-selected absorbers and their relation to the circumgalactic medium (CGM) of galaxies at low redshift (z<=0.1), based on the analysis of UV absorption spectra along 303 extragalactic lines of sight obtained with the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope (HST). Along a total redshift path of Dz=24 we identify 69 intervening SiIII systems that all show associated absorption from other low and high ions. We derive a bias-corrected number density of dN/dz(SiIII)=2.5 for absorbers with column densities log N(SiIII)>12.2. We develop a geometrical model for the absorption-cross section of the CGM around the local galaxy population and find excellent agreement between the model predictions and the observations. We further compare redshifts and positions of the absorbers with that of ~64,000 galaxies using archival galaxy-survey data. For the majority of the absorbers we identify possible host galaxies within 300 km/s of the absorbers and derive impact parameters rho<200 kpc, demonstrating that the spatial distributions of SiIII absorbers and galaxies are highly correlated. Our study indicates that the majority of SiIII-selected absorbers in our sample trace the CGM of nearby galaxies within their virial radii at a typical covering fraction of ~70 per cent. From a detailed ionization model we estimate that diffuse gas in the CGM around galaxies, as traced by SiIII, contains substantially more baryonic mass than their neutral interstellar medium.Comment: 32 pages, 17 figures; final version accepted for publication in A&

Conditions of the Development of Logistic Centers in Poland in the Context of European States Experiences

The article is, for the most part, the aftermath of his own examinations carried out in years 2007-2010 and concerning logistic centers development conditioning.Artykuł jest w znacznej mierze pokłosiem badań własnych autora przeprowadzonych w latach: 2007-2010 dotyczących uwarunkowań rozwoju centrów logistycznych

Pump frequency resonances for light-induced incipient superconductivity in YBa2_2Cu3_3O6.5_{6.5}

Optical excitation in the cuprates has been shown to induce transient superconducting correlations above the thermodynamic transition temperature, $T_C$, as evidenced by the terahertz frequency optical properties in the non-equilibrium state. In YBa$_2$Cu$_3$O$_{6+x}$ this phenomenon has so far been associated with the nonlinear excitation of certain lattice modes and the creation of new crystal structures. In other compounds, like La$_{2-x}$Ba$_x$CuO$_4$, similar effects were reported also for excitation at near infrared frequencies, and were interpreted as a signature of the melting of competing orders. However, to date it has not been possible to systematically tune the pump frequency widely in any one compound, to comprehensively compare the frequency dependent photo-susceptibility for this phenomenon. Here, we make use of a newly developed optical parametric amplifier, which generates widely tunable high intensity femtosecond pulses, to excite YBa$_2$Cu$_3$O$_{6.5}$ throughout the entire optical spectrum (3 - 750 THz). In the far-infrared region (3 - 25 THz), signatures of non-equilibrium superconductivity are induced only for excitation of the 16.4 THz and 19.2 THz vibrational modes that drive $c$-axis apical oxygen atomic positions. For higher driving frequencies (25 - 750 THz), a second resonance is observed around the charge transfer band edge at ~350 THz. These observations highlight the importance of coupling to the electronic structure of the CuO$_2$ planes, either mediated by a phonon or by charge transfer.Comment: 47 pages, 21 figures, 2 table

Integrating Augmented Interactive Geo visualizations and Open Government

Es gibt große Hoffnungen zivilgesellschaftliches Engagement im Rahmen von Open Government Initiativen neu zu gestalten. Das Ziel ist es, Bürgerbeteiligung mittels offener Interaktionen und Zugang zu Daten zu stärken und einen Schwerpunkt auf Transparenz, Partizipation und Kollaboration zu legen. Vor diesem Hintergrund formuliert und untersucht diese Arbeit einen Ansatz zur Förderung von bürgerschaftlichem Engagement mittels erweiterten und interaktiven Geo-visualisierungen (AIGs). AIGs nutzen Raum und Zeit als Integratoren, um Bürgern Kontextualisierung, Visualisierung und verschiedene Möglichkeiten zum Engagement zu bieten. Die Hauptforschungsfrage dieser Arbeit untersucht die Effekte von AIGs auf bürgerschaftliches Engagement, während vier Leitfragen Vorbedingungen und Herausforderungen untersuchen. Zusammenfassend werden ein Design Space für AIGs konzeptualisiert, potentielle Rollen der Zielgruppe beschrieben, Best Practices für die Publikation von räumlichen offenen Daten formuliert und es wurden drei AIG Prototypen für einzelne Bürgerbeteiligungsverfahren und Stufen entwickelt und evaluiert.High hopes are pinned to reshaping civic engagement in Open Government Initiatives that seek to open up governmental processes and data by using modern information and communication technologies. The aim is to facilitate citizen engagement through open interactions and access to data by emphasizing transparency, participation, and collaboration. This thesis formulates and evaluates an approach to facilitate citizen engagement with Augmented Interactive Geo-visualizations (AIGs). AIGs use space and time as integrators that allow citizens to contextualize, visualize and engage in different ways. The central research question of this thesis investigates the effects of AIGs on citizen engagement while four guiding questions look at pre-requisits and challenges. In summary, a design space for AIGs is conceptualized, potential roles of the target audience are described, best practices for publishing geospatial Open Data established, and three AIG prototypes have been developed and evaluated for specific instances and levels of citizen engagement

Efficient extraction of canonical spatial relationships using a recursive enumeration of k-subsets

The spatial arrangement of a chemical compound plays an important role regarding the related properties or activities. A straightforward approach to encode the geometry is to enumerate pairwise spatial relationships between k substructures, like functional groups or subgraphs. This leads to a combinatorial explosion with th

The modelling cycle for collective animal behaviour

Collective animal behaviour is the study of how interactions between individuals produce group level patterns, and why these interactions have evolved. This study has proved itself uniquely interdisciplinary, involving physicists, mathematicians, engineers as well as biologists. Almost all experimental work in this area is related directly or indirectly to mathematical models, with regular movement back and forth between models, experimental data and statistical fitting. In this paper, we describe how the modelling cycle works in the study of collective animal behaviour. We classify studies as addressing questions at different levels or linking different levels, i.e. as local, local to global, global to local or global. We also describe three distinct approaches—theory-driven, data-driven and model selection—to these questions. We show, with reference to our own research on species across different taxa, how we move between these different levels of description and how these various approaches can be applied to link levels together

Nonlinear lattice dynamics as a basis for enhanced superconductivity in YBa2Cu3O6.5

THz-frequency optical pulses can resonantly drive selected vibrational modes in solids and deform their crystal structure. In complex oxides, this method has been used to melt electronic orders, drive insulator to metal transitions or induce superconductivity. Strikingly, coherent interlayer transport strongly reminiscent of superconductivity can be transiently induced up to room temperature in YBa2Cu3O6+x. By combining femtosecond X-ray diffraction and ab initio density functional theory calculations, we determine here the crystal structure of this exotic non-equilibrium state. We find that nonlinear lattice excitation in normal-state YBa2Cu3O6+x at 100 K causes a staggered dilation/contraction of the Cu-O2 intra/inter- bilayer distances, accompanied by anisotropic changes in the in-plane O-Cu-O bond buckling. Density functional theory calculations indicate that these motions cause dramatic changes in the electronic structure. Amongst these, the enhancement in the dx2-y2 character of the in-plane electronic structure is likely to favor superconductivity.Comment: 28 pages, including Supplemen