342 research outputs found

    A set of programs for analysis of kinetic and equilibrium data

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    A program package that can be used for analysis of a wide range of kinetic and equilibrium data is described. The four programs were written in Turbo Pascal and run on PC, XT, AT and compatibles. The first of the programs allows the user to fit data with 16 predefined and one user-defined function, using two different non-linear least-squares procedures. Two additional programs are used to test both the evaluation of model functions and the least-squares fits. One of these programs uses two simple procedures to generate a Gaussian-distributed random variable that is used to simulate the experimental error of measurements. The last program simulates kinetics described by differential equations that cannot be solved analytically, using numerical integration. This program helps the user to judge the validity of steady-state assumptions or treatment of kinetic measurements as relaxation

    Symmetric and asymmetric evaluation of the Tokamap in comparison with direct symplectic integration

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    Comparing the Poincaré plots of the Tokamap and the underlying Hamiltonian system reveals large differences. This stems from the particular choice of evaluation of the singular perturbations present in the system (a series of δ functions). A symmetric evaluation approach is proposed and shown to yield results that almost perfectly match the Hamiltonian system. © 2005 The American Physical Society

    Baryon spectroscopy

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    About 120 baryons and baryon resonances are known, from the abundant nucleon with uu and dd light-quark constituents up to the recently discovered Ωb−=bss\Omega_b^-=bss, and the Ξb−=bsd\Xi_b^-=bsd which contains one quark of each generation. In spite of this impressively large number of states, the underlying mechanisms leading to the excitation spectrum are not yet understood. Heavy-quark baryons suffer from a lack of known spin-parities. In the light-quark sector, quark-model calculations have met with considerable success in explaining the low-mass excitations spectrum but some important aspects like the mass degeneracy of positive-parity and negative-parity baryon excitations are not yet satisfactorily understood. At high masses, above 1.8 GeV, quark models predict a very high density of resonances per mass interval which is not observed. In this review, issues are identified discriminating between different views of the resonance spectrum; prospects are discussed how open questions in baryon spectroscopy may find answers from photo- and electro-production experiments which are presently carried out in various laboratories.Comment: Review article, 53 pages, 40 figures, 23 Tables. Review of Modern Physics (accepted for publication

    Hypertension does not Affect Intracellular Calcium uptake in Human Platelets

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    The relationship between the Ca2+ transport of platelet endoplasmic reticulum and hypertension was analyzed in 17 untreated patients exhibiting various degrees of hypertension. Each patient underwent a 24-h recording of ambulatory blood pressure. Platelets from patients were permeabilized with saponin and the rate of ATP-driven thapsigargin-sensitive Ca2+ uptake determined using the fluorescent Ca2+ indicator fluo-3. No relationship between blood pressure (systolic, diastolic, day, night) and the rate of Ca2+ uptake into the sacroplasmic reticulum of platelets was found. A weak but insignificant correlation between Ca2+ uptake and the heart rate was noted. Therefore, the increase in cytosolic Ca2+ of platelets in hypertension may not be due to changes of the activity of Ca2+ uptake into the sacroplasmic reticulum. Am J Hypertens 1996;9:136-14

    The impact of the AO foundation on fracture care : an evaluation of 60 years AO foundation

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    Objectives Sixty years ago, the Association of Osteosynthesis (AO) was founded with the aim to improve fracture treatment and has since grown into one of the largest medical associations worldwide. Aim of this study was to evaluate AO's impact on science, education, patient care and the MedTech business. Design/methods Impact evaluations were conducted as appropriate for the individual domains: Impact on science was measured by analyzing citation frequencies of publications promoted by AO. Impact on education was evaluated by analyzing the evolution of number and location of AO courses. Impact on patient care was evaluated with a health economic model analyzing cost changes and years of life gained through the introduction of osteosynthesis in 17 high-income countries (HICs). Impact on MedTech business was evaluated by analyzing sales data of AO-associated products. Results Thirty-five AO papers and 2 major AO textbooks are cited at remarkable frequencies in high ranking journals with up to 2000 citations/year. The number of AO courses steadily increased with a total of 645'000 participants, 20‘000 teaching days and 2‘500 volunteer faculty members so far. The introduction of osteosynthesis saved at least 925 billion Swiss Francs [CHF] in the 17 HICs analyzed and had an impact on avoiding premature deaths comparable to the use of antihypertensive drugs. AO-associated products generated sales of 55 billion CHF. Conclusion AO's impact on science, education, patient care, and the MedTech business was significant because AO addressed hitherto unmet needs by combining activities that mutually enriched and reinforced each other

    Outcomes of retropupillary iris claw intraocular lens implantation combined with pars plana vitrectomy

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    PURPOSE: To report 12-month visual outcomes, incidence of intraocular pressure (IOP) changes and postoperative complications after pars plana vitrectomy with retropupillary implantation of an iris claw intraocular lens (IOL) in aphakic eyes after complicated cataract surgery and eyes with a dislocation of the IOL. METHODS: This is a retrospective analysis of eyes undergoing implantation of an iris claw IOL combined with pars plana vitrectomy from 1st of January 2009 until 30th of June 2018 after complicated cataract extraction with capsular loss (Group A) or dislocation of an IOL (Group B). Corrected distance visual acuity was analyzed in logarithm of the minimum angle of resolution (logMAR) units, IOP was recorded in mmHg. RESULTS: Eyes in Group A (n = 49) improved from a preoperative median visual acuity of 0.523 logMAR (Snellen 20/65) to 0.201 logMAR (Snellen 20/30), P 0.05. During 12 months in Group A, IOP >21 mmHg occurred in 9 (18.4%) eyes; no eye had an IOP 21 mmHg occurred in 15 (11.9%) eyes, IOP 21 mmHg or <6 mmHg at 12 months follow-up. CONCLUSION: The retropupillary implantation of an iris claw IOL with pars plana vitrectomy provides adequate visual rehabilitation and seems to be safe in IOP changes

    Analyzing Feshbach resonances -- A 6^6Li -133^{133}Cs case study

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    We provide a comprehensive comparison of a coupled channels calculation, the asymptotic bound state model (ABM), and the multichannel quantum defect theory (MQDT). Quantitative results for 6^6Li -133^{133}Cs are presented and compared to previously measured 6^6Li -133^{133}Cs Feshbach resonances (FRs) [M. Repp et al., Phys. Rev. A 87 010701(R) (2013)]. We demonstrate how the accuracy of the ABM can be stepwise improved by including magnetic dipole-dipole interactions and coupling to a non-dominant virtual state. We present a MQDT calculation, where magnetic dipole-dipole and second order spin-orbit interactions are included. A frame transformation formalism is introduced, which allows the assignment of measured FRs with only three parameters. All three models achieve a total rms error of < 1G on the observed FRs. We critically compare the different models in view of the accuracy for the description of FRs and the required input parameters for the calculations.Comment: 16 pages, 3 figures, 1 tabl

    Energy efficient machine tools

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    The growing global energy demand from industry results in significant ecological and economical costs. Aiming to decrease the impact of machining operations, an increasing number of research activities and publications regarding energy efficient machine tools and machining processes can be found in the literature. This keynote paper provides an overview of current machine- and process-related measures to improve the energy efficiency of metal cutting machine tools. Based on an analysis of the energy requirements of machine tool components, design measures to reduce the energy demand of main and support units are introduced. Next, methods for an energy efficient operation of machine tools are reviewed. Furthermore, latest developments and already available energy efficiency options in the machine tool industry are discussed. The paper concludes with recommendations and future research questions for more energy efficient machine tools

    A new locus for arrhythmogenic right ventricular cardiomyopathy (ARVD2) maps to chromosome 1q42-q43

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    Autosomal dominant arrhythmogenic right ventricular cardiomyopathy (ARVD, MIM 107970) is one of the major causes of juvenile sudden death. We have previously assigned the disease locus to chromosome 14q23-q24. Here we report on a novel variant of ARVD, which is transmitted associated to 1q42-q43 and is characterized by a concealed form, showing effort-induced polymorphic tachycardias. Since both loci ARVD1 and ARVD2 map in proximity of a-actinin genes, the possible implication of these myofibrillar proteins in the pathogenesis of ARVD is discussed. Two additional ARVD families, tested with markers of chromosomes 1q42-q43 and 14q23-q24, failed to show linkage, providing evidence of further genetic heterogeneit
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