954 research outputs found

    The fiscal lives of pandemics

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    Strain-Rate Frequency Superposition in Large-Amplitude Oscillatory Shear

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    In a recent work, Wyss, {\it et.al.} [Phys. Rev. Lett., {\bf 98}, 238303 (2007)] have noted a property of `soft solids' under oscillatory shear, the so-called strain-rate frequency superposition (SRFS). We extend this study to the case of soft solids under large-amplitude oscillatory shear (LAOS). We show results from LAOS studies in a monodisperse hydrogel suspension, an aqueous gel, and a biopolymer suspension, and show that constant strain-rate frequency sweep measurements with soft solids can be superimposed onto master curves for higher harmonic moduli, with the {\it same} shift factors as for the linear viscoelastic moduli. We show that the behavior of higher harmonic moduli at low frequencies in constant strain-rate frequency sweep measurements is similar to that at large strain amplitudes in strain-amplitude sweep tests. We show surface plots of the harmonic moduli and the energy dissipation rate per unit volume in LAOS for soft solids, and show experimentally that the energy dissipated per unit volume depends on the first harmonic loss modulus alone, in both the linear and the nonlinear viscoelastic regime.Comment: 10 pages, 25 figures, accepted for publication in Physical Review E. Incorporates referee comment

    Rationality as the Rule of Reason

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    The demands of rationality are linked both to our subjective normative perspective (given that rationality is a person-level concept) and to objective reasons or favoring relations (given that rationality is non-contingently authoritative for us). In this paper, I propose a new way of reconciling the tension between these two aspects: roughly, what rationality requires of us is having the attitudes that correspond to our take on reasons in the light of our evidence, but only if it is competent. I show how this view can account for structural rationality on the assumption that intentions and beliefs as such involve competent perceptions of downstream reasons, and explore various implications of the account

    Enhanced Tunnelling in a Hybrid of Single-Walled Carbon Nanotubes and Graphene

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    Transparent and conductive films (TCFs) are of great technological importance. The high transmittance, electrical conductivity and mechanical strength make single-walled carbon nanotubes (SWCNTs) a good candidate for their raw material. Despite the ballistic transport in individual SWCNTs, however, the electrical conductivity of their networks is limited by low efficiency of charge tunneling between the tube elements. Here, we demonstrate that the nanotube network sheet resistance at high optical transmittance is decreased by more than 50% when fabricated on graphene and thus provides a comparable improvement as widely adopted gold chloride (AuCl3\mathrm{AuCl_3}) doping. However, while Raman spectroscopy reveals substantial changes in spectral features of doped nanotubes, no similar effect is observed in presence of graphene. Instead, temperature dependent transport measurements indicate that graphene substrate reduces the tunneling barrier heights while its parallel conductivity contribution is almost negligible. Finally, we show that combining the graphene substrate and AuCl3\mathrm{AuCl_3} doping, the SWCNT thin films can exhibit sheet resistance as low as 36 Ω\Omega/sq. at 90% transmittance.Comment: 21 pages, 6 figure

    Coulomb blockade in one-dimensional arrays of high conductance tunnel junctions

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    Properties of one-dimensional (1D) arrays of low Ohmic tunnel junctions (i.e. junctions with resistances comparable to, or less than, the quantum resistance Rqh/e225.8R_{\rm q}\equiv h/e^2\approx 25.8 kΩ\Omega) have been studied experimentally and theoretically. Our experimental data demonstrate that -- in agreement with previous results on single- and double-junction systems -- Coulomb blockade effects survive even in the strong tunneling regime and are still clearly visible for junction resistances as low as 1 kΩ\Omega. We have developed a quasiclassical theory of electron transport in junction arrays in the strong tunneling regime. Good agreement between the predictions of this theory and the experimental data has been observed. We also show that, due to both heating effects and a relatively large correction to the linear relation between the half-width of the conductance dip around zero bias voltage, V1/2V_{1/2}, and the measured electronic temperature, such arrays are inferior to those conventionally used in the Coulomb Blockade Thermometry (CBT). Still, the desired correction to the half-width, ΔV1/2\Delta V_{1/2}, can be determined rather easily and it is proportional to the magnitude of the conductance dip around zero bias voltage, ΔG\Delta G. The constant of proportionality is a function of the ratio of the junction and quantum resistances, R/RqR/R_{\rm q}, and it is a pure strong tunneling effect.Comment: LaTeX file + five postscript figure

    Совершенствование региональных целевых программ – инструмента управления социально-экономическим развитием Одесского региона и его конкурентоспособностью

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    Розглянуто регіональні цільові програми розвитку Одеського регіону; виявлено недоліки діючого підходу до розробки й оцінки програм на регіональному рівні; подано рекомендації щодо загальних підходів до програмного управління, експертизи проектів; запропоновано експертний метод оцінки ефективності цільових програм із точки зору управління процесом розробки та реалізацією програм, своєчасного прийняття рішень. Ключові слова: регіональні цільові програми, соціально-економічний розвиток, регіон, управління, конкурентоспроможність.Рассмотрены региональные целевые программы развития Одесского региона; выявлены недостатки действующего подхода к разработке и оценке программ на региональном уровне; даны рекомендации по общим подходам к программному управлению, экспертизе проектов; предложен экспертный метод оценки эффективности целевых программ с точки зрения управления процессом разработки и ходом реализации программ, своевременного принятия решений. Ключевые слова: региональные целевые программы, социально-экономическое развитие, регион, управление, конкурентоспособность.The paper considers the regional target programs of Odessa region development. Shortcomings of the present approach to the development and evaluation of programs at the regional level are shown, recommendations on common approaches to program management and project appraisal are given; expert method for evaluating target programs is proposed from the view of managing the process of development and implementation of programs, timely decisions. Keywords: regional target programs, socio-economic development, region, management, competitiveness

    Quantum Conductance of the Single Electron Transistor

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    The quantum conductance of the single-electron tunneling (SET) transistor is investigated in this paper by the functional integral approach. The formalism is valid for arbitrary tunnel resistance of the junctions forming the SET transistor at any temperature. The path integrals are evaluated by the semiclassical method to yield an explicit non-perturbation form of the quantum conductance of the SET transistor. An anomaly of the quantum conductance is found if the tunnel resistances are much smaller than the quantum resistance. The dependence of the conductance on the gate voltage is also discussed.Comment: 4 pages including some mathe details of cond-mat/990806

    Clinical effectiveness and cost-effectiveness of pegvisomant for the treatment of acromegaly: a systematic review and economic evaluation

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    Background: Acromegaly, an orphan disease usually caused by a benign pituitary tumour, is characterised by hyper-secretion of growth hormone (GH) and insulin-like growth factor I (IGF-1). It is associated with reduced life expectancy, cardiovascular problems, a variety of insidiously progressing detrimental symptoms and metabolic malfunction. Treatments include surgery, radiotherapy and pharmacotherapy. Pegvisomant (PEG) is a genetically engineered GH analogue licensed as a third or fourth line option when other treatments have failed to normalise IGF-1 levels. Methods: Evidence about effectiveness and cost-effectiveness of PEG was systematically reviewed. Data were extracted from published studies and used for a narrative synthesis of evidence. A decision analytical economic model was identified and modified to assess the cost-effectiveness of PEG. Results: One RCT and 17 non-randomised studies were reviewed for effectiveness. PEG substantially reduced and rapidly normalised IGF-1 levels in the majority of patients, approximately doubled GH levels, and improved some of the signs and symptoms of the disease. Tumour size was unaffected at least in the short term. PEG had a generally safe adverse event profile but a few patients were withdrawn from treatment because of raised liver enzymes. An economic model was identified and adapted to estimate the lower limit for the cost-effectiveness of PEG treatment versus standard care. Over a 20 year time horizon the incremental cost-effectiveness ratio was pound81,000/QALY and pound212,000/LYG. To reduce this to pound30K/QALY would require a reduction in drug cost by about one third. Conclusion: PEG is highly effective for improving patients' IGF-1 level. Signs and symptoms of disease improve but evidence is lacking about long term effects on improved signs and symptoms of disease, quality of life, patient compliance and safety. Economic evaluation indicated that if current standards (UK) for determining cost-effectiveness of therapies were to be applied to PEG it would be considered not to represent good value for money
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