2,069 research outputs found

    Nuclear effects in atomic transitions

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    Atomic electrons are sensitive to the properties of the nucleus they are bound to, such as nuclear mass, charge distribution, spin, magnetization distribution, or even excited level scheme. These nuclear parameters are reflected in the atomic transition energies. A very precise determination of atomic spectra may thus reveal information about the nucleus, otherwise hardly accessible via nuclear physics experiments. This work reviews theoretical and experimental aspects of the nuclear effects that can be identified in atomic structure data. An introduction to the theory of isotope shifts and hyperfine splitting of atomic spectra is given, together with an overview of the typical experimental techniques used in high-precision atomic spectroscopy. More exotic effects at the borderline between atomic and nuclear physics, such as parity violation in atomic transitions due to the weak interaction, or nuclear polarization and nuclear excitation by electron capture, are also addressed.Comment: review article, 53 pages, 14 figure

    Testicular Adrenal Rest Tumours in Congenital Adrenal Hyperplasia

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    In adult patients with congenital adrenal hyperplasia (CAH), the presence of testicular adrenal rest tumours (TART) is an important complication leading to gonadal dysfunction and infertility. These tumours can be already found in childhood and puberty. In this paper, we review the embryological, histological, biochemical, and clinical features of TART and discuss treatment options

    Optimization by Quantum Annealing: Lessons from hard 3-SAT cases

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    The Path Integral Monte Carlo simulated Quantum Annealing algorithm is applied to the optimization of a large hard instance of the Random 3-SAT Problem (N=10000). The dynamical behavior of the quantum and the classical annealing are compared, showing important qualitative differences in the way of exploring the complex energy landscape of the combinatorial optimization problem. At variance with the results obtained for the Ising spin glass and for the Traveling Salesman Problem, in the present case the linear-schedule Quantum Annealing performance is definitely worse than Classical Annealing. Nevertheless, a quantum cooling protocol based on field-cycling and able to outperform standard classical simulated annealing over short time scales is introduced.Comment: 10 pages, 6 figures, submitted to PR

    «Белая дача» А.П. Чехова – как часть культурного ландшафта Крыма

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    Данная работа написана в рамках научного проекта кафедры культурологии «Культурные ландшафты Крыма» и посвящена рассмотрению «Белой дачи» А.П. Чехова (ныне Дом-музей А.П. Чехова в Ялте) как культурному ландшафту – результату сотворчества человека и природы

    Retention of Antimicrobial Activity in Plaque and Saliva following Mouthrinse Use in vivo

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    The aim of this study was to determine the contribution of plaque and saliva towards the prolonged activity, also called substantivity, of three antimicrobial mouthrinses (Listerine (R), Meridol (R), Crest Pro Health (R)), used in combination with a toothpaste (Prodent Coolmint (R)). Volunteers brushed for 4 weeks with a toothpaste without antimicrobial claims, while during the last 2 weeks half of the volunteers used an antimicrobial mouthrinse in addition to brushing. At the end of the experimental period, plaque and saliva samples were collected 6 h after oral hygiene, and bacterial concentrations and viabilities were determined. The contribution of plaque and saliva towards substantivity was assessed by combining plaque obtained after mechanical cleaning only with plaque and saliva obtained after additional use of an antimicrobial rinse. Subsequently, resulting viabilities of the combined plaques were determined. The viabilities of plaque samples after additional rinsing with mouthrinses were lower than of plaque obtained after mechanical cleaning only, regardless of the rinse involved. Moreover, plaque collected 6 h after rinsing with antimicrobial mouthrinses contained a surplus of antimicrobial activity. Only Listerine showed decreased vi

    Final State Interaction Effects in pol 3He(pol e,e'p)

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    Asymmetries in quasi-elastic pol 3He(pol e,e'p) have been measured at a momentum transfer of 0.67 (GeV/c)^2 and are compared to a calculation which takes into account relativistic kinematics in the final state and a relativistic one-body current operator. With an exact solution of the Faddeev equation for the 3He-ground state and an approximate treatment of final state interactions in the continuum good agreement is found with the experimental data.Comment: 11 pages, 6 figures, submitted to Phys. Lett. B, revised version, sensitivity study to relativity and NN-potential adde

    Purpose in life in patients with rheumatoid arthritis

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    To evaluate the role of purpose in life among people with rheumatoid arthritis (RA), a questionnaire comprising the Purpose in Life test (PIL) and the purpose in life dimension of the Psychological Well-Being test (PWB-pil) was sent to a random sample of 300 patients with RA. Additional questions comprised sociodemographic and disease characteristics, physical, mental and social functioning, coping (Coping with rheumatic stressors questionnaire), and quality of life (RAND-36). Associations between sociodemographic and disease characteristics, physical, mental and social functioning, and coping on the one side and the two measures of purpose in life on the other side and associations between the two purpose of life measures and physical and mental dimensions of quality of life were assessed by means of univariate and multivariate regression analyses. The response rate was 156 of 300 (52%). The median PIL and PWB-pil scores were 103 (range 63–131) and 82 (41–110), respectively. A lower age, a better mental health status, and an optimistic coping style were significantly associated with both higher PIL and PWB-pil scores, whereas more participation in leisure and/or social activities was associated with a higher PIL score. It was found that the PIL and PWB-pil contributed independently and significantly to the mental component summary scale of the RAND-36. In RA patients, lower age, a better mental health status, an optimistic coping style, and participation in leisure and/or social activities were significantly associated with more sense of purpose in life. Purpose in life pays a significant and independent contribution to the mental component of quality of life. These findings highlight the significance of the concept of purpose in life in patients with RA

    Design Principles for Energy-Efficient Legged Locomotion and Implementation on the MIT Cheetah Robot

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    This paper presents the design principles for highly efficient legged robots, the implementation of the principles in the design of the MIT Cheetah, and the analysis of the high-speed trotting experimental results. The design principles were derived by analyzing three major energy-loss mechanisms in locomotion: heat losses from the actuators, friction losses in transmission, and the interaction losses caused by the interface between the system and the environment. Four design principles that minimize these losses are discussed: employment of high torque-density motors, energy regenerative electronic system, low loss transmission, and a low leg inertia. These principles were implemented in the design of the MIT Cheetah; the major design features are large gap diameter motors, regenerative electric motor drivers, single-stage low gear transmission, dual coaxial motors with composite legs, and the differential actuated spine. The experimental results of fast trotting are presented; the 33-kg robot runs at 22 km/h (6 m/s). The total power consumption from the battery pack was 973 W and resulted in a total cost of transport of 0.5, which rivals running animals' at the same scale. 76% of the total energy consumption is attributed to heat loss from the motor, and the remaining 24% is used in mechanical work, which is dissipated as interaction loss as well as friction losses at the joint and transmission.United States. Defense Advanced Research Projects Agency (M3 Program

    Design of a five-axis ultra-precision micro-milling machine—UltraMill. Part 1: Holistic design approach, design considerations and specifications

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    High-accuracy three-dimensional miniature components and microstructures are increasingly in demand in the sector of electro-optics, automotive, biotechnology, aerospace and information-technology industries. A rational approach to mechanical micro machining is to develop ultra-precision machines with small footprints. In part 1 of this two-part paper, the-state-of-the-art of ultra-precision machines with micro-machining capability is critically reviewed. The design considerations and specifications of a five-axis ultra-precision micro-milling machine—UltraMill—are discussed. Three prioritised design issues: motion accuracy, dynamic stiffness and thermal stability, formulate the holistic design approach for UltraMill. This approach has been applied to the development of key machine components and their integration so as to achieve high accuracy and nanometer surface finish
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