Skyrmions, Rational Maps & Scaling Identities

Starting from approximate Skyrmion solutions obtained using the rational map ansatz, improved approximate Skyrmions are constructed using scaling arguments. Although the energy improvement is small, the change of shape clarifies whether the true Skyrmions are more oblate or prolate.Comment: 13 pages, 3 figure

The 1996 research assessment exercise : the library and information management panel

Reports on the 1996 Research Assessment Exercise (RAE), the fourth such exercise aimed at providing funding councils of UK universities (including former polytechnics) with the necessary data to rate the quality of UK academic research for predetermined units of assessment in order to fund research selectively. Previous RAEs were conducted in 1986, 1989, and 1992 (for a report of the 1992 RAE see JOLIS 26 (3) Sep 94, 141-7 (LISA ref. 9409765)). Reports generally on the work of the Library and Information Management Panel in agreeing criteria specific to their assessment task, particularly the five principal modes of publication: research monographs; articles in scholarly periodicals; refereed conference papers; published research reports; and book chapters. Discusses the methodology used by the Panel, research submissions received and the overall results

Prevalence, incidence burden and clinical impact of healthcare-associated infections and antimicrobial resistance: a national prevalent cohort study in acute care hospitals in Greece

Purpose: Assessing the overall burden of healthcare-associated infections (HAIs) is challenging, but imperative in evaluating the cost-effectiveness of infection control programs. This study aimed to estimate the point prevalence and annual incidence of HAIs in Greece and assess the excess length of stay (LOS) and mortality attributable to HAIs, overall and for main infection sites and tracer antimicrobial resistance (AMR) phenotypes and pathogens. Patients and methods: This prevalent cohort study used a nationally representative cross-section of 8,247 inpatients in 37 acute-care hospitals to record active HAIs of all types at baseline and overall LOS and in-hospital mortality up to 90 days following hospital admission. HAI incidence was estimated using prevalence-to-incidence conversion methods. Excess mortality and LOS were assessed by Cox regression and multistate models correcting for confounding and time-dependent biases. Results: HAIs were encountered with daily prevalence of 9.1% (95% confidence interval [CI] 7.8% – 10.6%). The estimated annual HAI incidence was 5.2% (95%CI 4.4% – 5.3%), corresponding to approximately 121,000 (95%CI 103,500 – 123,700) affected patients each year in the country. 90-day mortality risk was increased by 80% in patients with HAI compared to those without HAI (adjusted hazard ratio 1.8; 95%CI 1.3 – 2.6). Lower respiratory tract infections, bloodstream infections and multiple concurrent HAIs doubled the risk of death, whereas surgical site and urinary-tract infections were are not associated with increased mortality. AMR had significant impact on the daily risk of 90-day mortality, which was increased by 90%-110% in patients infected by carbapenem-resistant gram-negative pathogens (CR-GNBs). HAIs increased LOS for an average of 4.3 (95% CI 2.4– 6.2) additional days. Mean excess LOS exceeded 20 days in infections caused by major CR-GNBs. Conclusion: HAIs, alongside with increasing AMR, pose significant burden to the hospital system. Burden estimates obtained in this study will be valuable in future evaluations of infection prevention programs

Radon measurements along active faults in the Langadas Basin, northern Greece

A network of three radon stations has been established in the Langadas Basin, northern Greece for radon monitoring by various techniques in earthquake prediction studies. Specially made devices with plastic tubes including Alpha Tracketch Detectors (ATD) were installed for registering alpha particles from radon and radon decay products exhaled from the ground, every 2 weeks, by using LR-115, type II, non-strippable Kodak films, starting from December 1996. Simultaneous measurements started using Lucas cells alpha spectrometer for instantaneous radon measurements in soil gas, before and after setting ATDs at the radon stations. Continuous monitoring of radon gas exhaling from the ground started from the middle of August 1999 by using silicon diode detectors, which simultaneously register meteorological parameters, such as rainfall, temperature and barometric pressure. The obtained data were studied together with the data of seismic events, such as the magnitude, <i>M_L</i>, of earthquakes that occurred at the Langadas Basin during the period of measurements, as registered by the Laboratory of Geophysics, Aristotle University of Thessaloniki, in order to find out any association between them

Topological discrete kinks

A spatially discrete version of the general kink-bearing nonlinear Klein-Gordon model in (1+1) dimensions is constructed which preserves the topological lower bound on kink energy. It is proved that, provided the lattice spacing h is sufficiently small, there exist static kink solutions attaining this lower bound centred anywhere relative to the spatial lattice. Hence there is no Peierls-Nabarro barrier impeding the propagation of kinks in this discrete system. An upper bound on h is derived and given a physical interpretation in terms of the radiation of the system. The construction, which works most naturally when the nonlinear Klein-Gordon model has a squared polynomial interaction potential, is applied to a recently proposed continuum model of polymer twistons. Numerical simulations are presented which demonstrate that kink pinning is eliminated, and radiative kink deceleration greatly reduced in comparison with the conventional discrete system. So even on a very coarse lattice, kinks behave much as they do in the continuum. It is argued, therefore, that the construction provides a natural means of numerically simulating kink dynamics in nonlinear Klein-Gordon models of this type. The construction is compared with the inverse method of Flach, Zolotaryuk and Kladko. Using the latter method, alternative spatial discretizations of the twiston and sine-Gordon models are obtained which are also free of the Peierls-Nabarro barrier.Comment: 14 pages LaTeX, 7 postscript figure

Deep stratosphere-to-troposphere transport (STT) over SE Europe: a complex case study captured by enhanced ⁷Be concentrations at the surface of a low topography region

International audienceIn this study we present a complex case study of a Stratosphere-to-Troposphere Transport (STT) event down to the surface of a low topography region in Northern Greece, during the second fortnight of March 2000. During this event our surface station at Livadi (23°15 E/40°32 N, 850 m a.s.l.), was influenced by very different synoptic systems developing over Eastern Europe, N. America and the N. Atlantic, the last one evolving to a cut-off low over France/Spain. This is the first study, to our knowledge, that presents a down to the surface STT event in the eastern Mediterranean. The intrusion is primarily captured with the use of the cosmogenic radionuclide 7Be, which increased to 9.07 mBq m-3 and 9.37 mBq m-3 on 30 and 31 March 2000, respectively. A 7Be concentration of around 8 mBq m-3 recorded during parallel measurements at Thessaloniki (20 m a.s.l.) gives strong evidence that air of stratospheric origins has even gone down to sea level. A rapid increase of 10?15 ppb is also observed in the surface ozone concentration on 31 March 2000. The relative increase of both tracers is consistent with a volume fraction of stratospheric air at the surface of about 5%, but the substantial increase in 7Be flags more clearly the event. Trajectory analyses, in conjunction with the evolution of the synoptic situation described by potential vorticity maps, are used for the exact identification of the different intrusions and the attribution of each intruding parcel of stratospheric air to a certain filament of high PV. Finally, the persistency of the stratospheric layers in the troposphere is another interesting point of this case study. The vast majority of the trajectories spent 7?10 days in the troposphere before reaching the surface at Livadi station

The bubbles of matter from multiskyrmions

The multiskyrmions with large baryon number B given by rational map (RM) ansaetze can be described reasonably well within the domain wall approximation, or as spherical bubbles with energy and baryon number density concentrated at their boundary. A special class of profile functions is considered approximating the true profile and domain wall behaviour at the same time. An upper bound is obtained for the masses of RM multiskyrmions which is close to the calculated masses, especially at large B. The gap between rigorous upper and lower bounds for large B multiskyrmions is less than 4%. The basic properties of such bubbles of matter are investigated, some of them being of universal character, i.e. they do not depend on baryon number of configuration and on the number of flavors. As a result, the lagrangian of the Skyrme type models provides field theoretical realization of the bag model of special kind.Comment: 7 pages, no figure

Solutions of the Generic Non-Compact Weyl Equation

In this paper, solutions of the generic non-compact Weyl equation are obtained. In particular, by identifying a suitable similarity transformation and introducing a non-trivial change of variables we are able to implement azimuthal dependence on the solutions of the diagonal non-compact Weyl equation. We also discuss some open questions related to the construction of infinite BPS monopole configurations.Comment: 12 pages, Latex. Few extra comments and a reference adde

Complete Supersymmetric Quantum Mechanics of Magnetic Monopoles in N=4 SYM Theory

We find the most general low energy dynamics of 1/2 BPS monopoles in the N=4 supersymmetric Yang-Mills theories (SYM) when all six adjoint Higgs expectation values are turned on. When only one Higgs is turned on, the Lagrangian is purely kinetic. When all six are turned on, however, this moduli space dynamics is augmented by five independent potential terms, each in the form of half the squared norm of a Killing vector field on the moduli space. A generic stationary configuration of the monopoles can be interpreted as stable non BPS dyons, previously found as non-planar string webs connecting D3-branes. The supersymmetric extension is also found explicitly, and gives the complete quantum mechanics of monopoles in N=4 SYM theory. We explore its supersymmetry algebra.Comment: Errors in the SUSY algebra corrected. The version to appear in PR