High-tech and low-tech orthopaedic surgery in Sub-Saharan Africa

BACKGROUND: Zambia's governmental health system suffers from shortage of surgical supplies and poor management skills for the sparse resources at hand. The situation has been worsened by the dual epidemics of HIV disease and tuberculosis. On the other hand the private medical sector has benefited greatly from less bureaucracy under the goverment of the Movement for Multi-party Democracy. DISCUSSION: The Zambian-Italian Orthopaedic Hospital in Lusaka is a well organized small unit providing free treatment of physically disabled children. The running costs are met from the fees charged for private consultations, supplemented by donations. State of the art surgical techniques are being used for congenital and acquired musculo-skeletal abnormalities. Last year 513 patients were operated upon free of charge and 320 operations were performed on private patients

A general solution for the quark propagator in two-dimensional covariant gauge QCD

We have investigated a closed set of equations for the quark propagator, which has been obtained earlier within a new, nonperturbative approach to two-dimencional covariant gauge QCD. It is shown that this theory implies quark confinement (the quark propagator has no poles, indeed), as well as dynamical breakdown of chiral symmetry (a chiral symmetry preserving solution is forbidden). The above-mentioned set of equations can be exactly solved in the chiral limit. We develop an analytical formalism, the so-called chiral perturbation theory at the fundamental quark level, which allows one to find solution for the quark propagator in powers of the light quark masses. Each correction satisfies the differential equation, which can be formally solved. We develop also an analytical formalism which alows one to find solution for the quark propagator in the inverse powers of the heavy quark masses. IT coincides with free heavy quark propagator up to terms of order $1/m_Q^3$, where $m_Q$ is the heavy quark mass. So this solution automatically possesses the heavy quark flavor symmetry up to terms of order $1/m_Q$. At the same time, we have found a general solution for the heavy quark propagator, which by no means can be reduced to the free one.Comment: 12 pages, two figures, no tables, typos are correcte

Diffusion and jump-length distribution in liquid and amorphous Cu33_{33}Zr67_{67}

Using molecular dynamics simulation, we calculate the distribution of atomic jum ps in Cu$_{33}$Zr$_{67}$ in the liquid and glassy states. In both states the distribution of jump lengths can be described by a temperature independent exponential of the length and an effective activation energy plus a contribution of elastic displacements at short distances. Upon cooling the contribution of shorter jumps dominates. No indication of an enhanced probability to jump over a nearest neighbor distance was found. We find a smooth transition from flow in the liquid to jumps in the g lass. The correlation factor of the diffusion constant decreases with decreasing temperature, causing a drop of diffusion below the Arrhenius value, despite an apparent Arrhenius law for the jump probability

DATASET2050 D5.2 - Assessment execution

Over recent years there has been an increasing effort to enhance European door-to-door mobility. Several initiatives have focused on improving the seamlessness, effectiveness and predictability of the European transport system through improving the related systems, technologies, concepts or processes. In an effort to establish a concrete methodology for assessing the system's current performance, this document describes a data-driven model centred on the current and future performance of European mobility. Included in this study, but not restricted to, is data and insight related to the Flightpath 2050 goal that states "90% of travellers within Europe [will be] able to complete their journey, door-to-door within four hours" where this journey includes at least one leg by air. In this report, the current door-to-door times and prices are quantified, dis-aggregated by passenger profile, door-to-door phase (door-kerb-gate-gate-kerb-door) and airport considered. In addition, major bottlenecks are identified that are hindering the 4-hour goal

X-ray full field microscopy at 30 KeV

In our X-ray full field microscopy experiments, we demonstrated a resolution better than 260 nm over the entire field of view of 80 μm x 80 μm at 30 keV. Our experimental setup at PETRA III, P05, had a length of about 5 m consisting of an illumination optics, an imaging lens and a detector. For imaging, we used a compound refractive lens (CLR) consisting of mr-L negative photo resist, which was fabricated by deep X-ray lithography. As illumination optics, we choose a refractive rolled X-ray prism lens, which was adapted to the numerical aperture of the imaging lens

The ALICE Silicon Pixel Detector Control system and online calibration tools

The ALICE Silicon Pixel Detector (SPD) contains nearly 107 hybrid pixel cells. The operation of the SPD requires online control and monitoring of some 2000 parameters and » 50000DACs. Information for each channel is stored in a configuration database. Timing and data management (» 6GB of raw data each calibration) are critical issues. An overview of the SPD electronics read out chain and of the detector control system is given with a detailed description of the front-end controls and the calibration strategy. The status of commissioning and a preliminary evaluation of detector performance are presented

Photoelektronenspektren substituierter Pyridine und Benzole und ihre Interpretation durch die CNDO/SWW-Methode

Es werden die He I und He II Photoelektronenspektren (PE) des Benzols, Toluols, Chlorbenzols, Pyridins und der 3 isomeren Picoline und Chlorpyridine vorgestellt und auf der Grundlage von :J3erechnungen mit einem modifizierten CNDO-Verfahren diskutiert. Aus der experimentell und theoretisch relativ gesicherten Zuordnung des Benzols und des Pyridins lassen sich innerhalb der verwendeten MO-Methode fiir die berechneten Orbitalenergien E; Korekturfaktoren ermitteln, die nach bestimmten Symmetrieeigenschaften klassifiziert werden kiinnen. Mittels dieser GriiBen werden die PE-Spektren der substituierten Benzole und Pyridine zugeordnet

Isotope shift in the dielectronic recombination of three-electron ^{A}Nd^{57+}

Isotope shifts in dielectronic recombination spectra were studied for Li-like ^{A}Nd^{57+} ions with A=142 and A=150. From the displacement of resonance positions energy shifts \delta E^{142,150}(2s-2p_1/2)= 40.2(3)(6) meV (stat)(sys)) and \delta E^{142,150}(2s-2p_3/2) = 42.3(12)(20) meV of 2s-2p_j transitions were deduced. An evaluation of these values within a full QED treatment yields a change in the mean-square charge radius of ^{142,150}\delta = -1.36(1)(3) fm^2. The approach is conceptually new and combines the advantage of a simple atomic structure with high sensitivity to nuclear size.Comment: 10 pages, 3 figures, accepted for publication in Physical Review Letter

Social Learning Analytics in Computer-Supported Collaborative Learning Environments: A Systematic Review of Empirical Studies

Social learning analytics (SLA) is a promising approach for identifying students’ social learning processes in computer-supported collaborative learning (CSCL) environments. To identify the main characteristics of SLA, gaps and future opportunities for this emerging approach, we systematically identified and analyzed 36 SLA-related studies conducted between 2011 and 2020. We focus on SLA implementation and methodological characteristics, educational focus, and the studies’ theoretical perspectives. The results show the predominance of SLA in formal and fully online settings with social network analysis (SNA) a dominant analytical technique. Most SLA studies aimed to understand students’ learning processes and applied the social constructivist perspective as a lens to interpret students’ learning behaviors. However, (i) few studies involve teachers in developing SLA tools, and rarely share SLA visualizations with teachers to support teaching decisions; (ii) some SLA studies are atheoretical; and (iii) the number of SLA studies integrating more than one analytical approach remains limited. Moreover, (iv) few studies leveraged innovative network approaches (e.g., epistemic network analysis, multimodal network analysis), and (v) studies rarely focused on temporal patterns of students’ interactions to assess how students’ social and knowledge networks evolve over time. Based on the findings and the gaps identified, we present methodological, theoretical and practical recommendations for conducting research and creating tools that can advance the field of SLA