Of course we share! Testing Assumptions about Social Tagging Systems

Social tagging systems have established themselves as an important part in today's web and have attracted the interest from our research community in a variety of investigations. The overall vision of our community is that simply through interactions with the system, i.e., through tagging and sharing of resources, users would contribute to building useful semantic structures as well as resource indexes using uncontrolled vocabulary not only due to the easy-to-use mechanics. Henceforth, a variety of assumptions about social tagging systems have emerged, yet testing them has been difficult due to the absence of suitable data. In this work we thoroughly investigate three available assumptions - e.g., is a tagging system really social? - by examining live log data gathered from the real-world public social tagging system BibSonomy. Our empirical results indicate that while some of these assumptions hold to a certain extent, other assumptions need to be reflected and viewed in a very critical light. Our observations have implications for the design of future search and other algorithms to better reflect the actual user behavior

Quantum and classical spin network algorithms for qq-deformed Kogut-Susskind gauge theories

Treating the infinite-dimensional Hilbert space of non-abelian gauge theories is an outstanding challenge for classical and quantum simulations. Here, we introduce $q$-deformed Kogut-Susskind lattice gauge theories, obtained by deforming the defining symmetry algebra to a quantum group. In contrast to other formulations, our proposal simultaneously provides a controlled regularization of the infinite-dimensional local Hilbert space while preserving essential symmetry-related properties. This enables the development of both quantum as well as quantum-inspired classical Spin Network Algorithms for $q$-deformed gauge theories (SNAQs). To be explicit, we focus on SU(2)$_k$ gauge theories, that are controlled by the deformation parameter $k$ and converge to the standard SU(2) Kogut-Susskind model as $k \rightarrow \infty$. In particular, we demonstrate that this formulation is well suited for efficient tensor network representations by variational ground-state simulations in 2D, providing first evidence that the continuum limit can be reached with $k = \mathcal{O}(10)$. Finally, we develop a scalable quantum algorithm for Trotterized real-time evolution by analytically diagonalizing the SU(2)$_k$ plaquette interactions. Our work gives a new perspective for the application of tensor network methods to high-energy physics and paves the way for quantum simulations of non-abelian gauge theories far from equilibrium where no other methods are currently available.Comment: 5+4 pages, 4+1 figure

Characterization of Lomer junctions based on the Lomer arm length distribution in dislocation networks

During the plastic deformation of crystalline materials, 3d dislocation networks form based on dislocation junctions. Particularly, immobile Lomer junctions are essential for the stability of dislocation networks. However, the formed Lomer junctions can unzip and dissolve again, if the linked mobile dislocations of the Lomer junction - the Lomer arms - experience sufficiently high resolved shear stresses. To generate a better understanding of the dislocation network stability and to pave the way to a general stability criterion of dislocation networks, we investigate the Lomer arm length distribution in dislocation networks by analyzing discrete dislocation dynamics simulation data of tensile-tested aluminum single crystals. We show that an exponential distribution fits best to the Lomer arm length distribution in the systems considered, which is independent of the crystal orientation. The influence of the slip system activity on the Lomer arm length distribution is discussed

The spectrum and solutions of the generalized BFKL equation for total cross section

The colour dipole cross section is the principal quantity in the lightcone $s$-channel description of the diffractive scattering. Recently we have shown that the dipole cross section satisfies the generalized BFKL equation. In this paper we discuss properties and solutions of our generalized BFKL equation with allowance for the finite gluon correlation radius $R_{c}$. The latter is introduced in a gauge invariant manner. We present estimates of the intercept of the pomeron and find the asymptotic form of the dipole cross section.Comment: 18 pages, 3 figures upon request from [email protected]

The provision of out-of-hours care and associated costs in an urban area of Switzerland: a cost description study

BACKGROUND: In Switzerland, General Practitioners (GPs) play an important role for out-of-hours emergency care as one service option beside freely accessible and costly emergency departments of hospitals. The aim of this study was to evaluate the services provided and the economic consequences of a Swiss GP out-of-hours service. METHODS: GPs participating in the out-of-hours service in the city of Zurich collected data on medical problems (ICPC coding), mode of contact, mode of resource use and services provided (time units; diagnostics; treatments). From a health care insurance perspective, we assessed the association between total costs and its two components (basic costs: charges for time units and emergency surcharge; individual costs: charges for clinical examination, diagnostics and treatment in the discretion of the GP). RESULTS: 125 GPs collected data on 685 patient contacts. The most prevalent health problems were of respiratory (24%), musculoskeletal (13%) and digestive origin (12%). Home visits (61%) were the most common contact mode, followed by practice (25%) and telephone contacts (14%). 82% of patients could be treated by ambulatory care. In 20% of patients additional technical diagnostics, most often laboratory tests, were used. The mean total costs for one emergency patient contact were €144 (95%-CI: 137-151). The mode of contact was an important determinant of total costs (mean total costs for home visits: €176 [95%-CI: 168-184]; practice contact: €90 [95%-CI: 84-98]; telephone contact: €48 [95%-CI: 40-55]). Basic costs contributed 83% of total costs for home visits and 70% of total costs for practice contacts. Individual mean costs were similarly low for home visits (€30) and practice contacts (€27). Medical problems had no relevant influence on this cost pattern. CONCLUSIONS: GPs managed most emergency demand in their out-of-hours service by ambulatory care. They applied little diagnostic testing and basic care. Our findings are of relevance for policy makers even from other countries with different pricing policies. Policy makers should be interested in a reimbursement system promoting out-of-hours care run by GPs as one valuable service option

Feedback cooling of a single trapped ion

Based on a real-time measurement of the motion of a single ion in a Paul trap, we demonstrate its electro-mechanical cooling below the Doppler limit by homodyne feedback control (cold damping). The feedback cooling results are well described by a model based on a quantum mechanical Master Equation.Comment: 4 pages, 3 figure

Variability of linezolid concentrations after standard dosing in critically ill patients: a prospective observational study.

Severe infections in intensive care patients show high morbidity and mortality rates. Linezolid is an antimicrobial drug frequently used in critically ill patients. Recent data indicates that there might be high variability of linezolid serum concentrations in intensive care patients receiving standard doses. This study was aimed to evaluate whether standard dosing of linezolid leads to therapeutic serum concentrations in critically ill patients

An Open-System Quantum Simulator with Trapped Ions

The control of quantum systems is of fundamental scientific interest and promises powerful applications and technologies. Impressive progress has been achieved in isolating the systems from the environment and coherently controlling their dynamics, as demonstrated by the creation and manipulation of entanglement in various physical systems. However, for open quantum systems, engineering the dynamics of many particles by a controlled coupling to an environment remains largely unexplored. Here we report the first realization of a toolbox for simulating an open quantum system with up to five qubits. Using a quantum computing architecture with trapped ions, we combine multi-qubit gates with optical pumping to implement coherent operations and dissipative processes. We illustrate this engineering by the dissipative preparation of entangled states, the simulation of coherent many-body spin interactions and the quantum non-demolition measurement of multi-qubit observables. By adding controlled dissipation to coherent operations, this work offers novel prospects for open-system quantum simulation and computation.Comment: Pre-review submission to Nature. For an updated and final version see publication. Manuscript + Supplementary Informatio

Immunothrombotic Dysregulation in COVID-19 Pneumonia is Associated with Respiratory Failure and Coagulopathy

Background: SARS-CoV-2 infection causes severe pneumonia (COVID-19), but the mechanisms of subsequent respiratory failure and complicating renal and myocardial involvement are poorly understood. In addition, a systemic prothrombotic phenotype has been reported in COVID-19 patients. Methods: A total of 62 subjects were included in our study (n=38 patients with RT-PCR confirmed COVID-19 and n=24 non-COVID-19 controls). We performed histopathological assessment of autopsy cases, surface-marker based phenotyping of neutrophils and platelets, and functional assays for platelet, neutrophil functions as well as coagulation tests. Results: We provide evidence that organ involvement and prothrombotic features in COVID-19 are linked by immunothrombosis. We show that in COVID-19 inflammatory microvascular thrombi are present in the lung, kidney, and heart, containing neutrophil extracellular traps associated with platelets and fibrin. COVID-19 patients also present with neutrophil-platelet aggregates and a distinct neutrophil and platelet activation pattern in blood, which changes with disease severity. Whereas cases of intermediate severity show an exhausted platelet and hyporeactive neutrophil phenotype, severely affected COVID-19 patients are characterized by excessive platelet and neutrophil activation compared to healthy controls and non-COVID-19 pneumonia. Dysregulated immunothrombosis in SARS-CoV-2 pneumonia is linked to both ARDS and systemic hypercoagulability. Conclusions: Taken together, our data point to immunothrombotic dysregulation as a key marker of disease severity in COVID-19. Further work is necessary to determine the role of immunothrombosis in COVID-19