90 research outputs found

    A numerical method for the expected penalty–reward function in a Markov-modulated jump–diffusion process.

    Get PDF
    A generalization of the Cramér–Lundberg risk model perturbed by a diffusion is proposed. Aggregate claims of an insurer follow a compound Poisson process and premiums are collected at a constant rate with additional random fluctuation. The insurer is allowed to invest the surplus into a risky asset with volatility dependent on the level of the investment, which permits the incorporation of rational investment strategies as proposed by Berk and Green (2004). The return on investment is modulated by a Markov process which generalizes previously studied settings for the evolution of the interest rate in time. The Gerber–Shiu expected penalty–reward function is studied in this context, including ruin probabilities (a first-passage problem) as a special case. The second order integro-differential system of equations that characterizes the function of interest is obtained. As a closed-form solution does not exist, a numerical procedure based on the Chebyshev polynomial approximation through a collocation method is proposed. Finally, some examples illustrating the procedure are presentedExpected penalty–reward function; Markov-modulated process; Jump–diffusion process; Volterra integro-differential system of equations;

    Evolution of the fishtail-effect in pure and Ag-doped MG-YBCO

    Full text link
    We report on magnetic measurements carried out in a textured YBa2_2Cu3_3O7−δ_{7-\delta} and YBa2_2(Cu1−x_{1-x}Agx_x)3_3O7−δ_{7-\delta} (at x≈x \approx 0.02) crystals. The so-called fishtail-effect (FE) or second magnetization peak has been observed in a wide temperature range 0.4~<T/Tc<<T/T_c<~0.8 for H∥c\textbf{H}\parallel c. The origin of the FE arises for the competition between surface barrier and bulk pinning. This is confirmed in a non-monotonically behavior of the relaxation rate RR. The value HmaxH_{max} for Ag-doped crystals is larger than for the pure one due to the presence of additional pinning centers, above all on silver atoms.Comment: 6 pages, 6 figure

    Studies of cracking behavior in melt-processed YBCO bulk superconductors

    Get PDF
    An important phenomenon in bulk superconductors fabricated by top-seeded-melt growth (TSMG) is the formation of cracks due to the inherent brittleness of the YBa2Cu3O7-δ (Y-123) phase matrix. These form during the fabrication of the superconducting monolith and play an important role in the limitation of current flow. However, cracks may also form during cooling cycles of the sample to liquid nitrogen temperatures. In this investigation, macrocracks along the c-direction, in particular were analyzed microscopically before and after cooling. In addition we attempt to resolve the c-axis macrocrack formation pattern using the magnetoscan technique

    Effect of alendronate on post-traumatic osteoarthritis induced by anterior cruciate ligament rupture in mice.

    Get PDF
    IntroductionPrevious studies in animal models of osteoarthritis suggest that alendronate (ALN) has antiresorptive and chondroprotective effects, and can reduce osteophyte formation. However, these studies used non-physiologic injury methods, and did not investigate early time points during which bone is rapidly remodeled prior to cartilage degeneration. The current study utilized a non-invasive model of knee injury in mice to investigate the effect of ALN treatment on subchondral bone changes, articular cartilage degeneration, and osteophyte formation following injury.MethodsNon-invasive knee injury via tibial compression overload or sham injury was performed on a total of 90 mice. Mice were treated with twice weekly subcutaneous injections of low-dose ALN (40&nbsp;Îźg/kg/dose), high-dose ALN (1,000&nbsp;Îźg/kg/dose), or vehicle, starting immediately after injury until sacrifice at 7, 14 or 56&nbsp;days. Trabecular bone of the femoral epiphysis, subchondral cortical bone, and osteophyte volume were quantified using micro-computed tomography (ÎźCT). Whole-joint histology was performed at all time points to analyze articular cartilage and joint degeneration. Blood was collected at sacrifice, and serum was analyzed for biomarkers of bone formation and resorption.ResultsÎźCT analysis revealed significant loss of trabecular bone from the femoral epiphysis 7 and 14&nbsp;days post-injury, which was effectively prevented by high-dose ALN treatment. High-dose ALN treatment was also able to reduce subchondral bone thickening 56&nbsp;days post-injury, and was able to partially preserve articular cartilage 14&nbsp;days post-injury. However, ALN treatment was not able to reduce osteophyte formation at 56&nbsp;days post-injury, nor was it able to prevent articular cartilage and joint degeneration at this time point. Analysis of serum biomarkers revealed an increase in bone resorption at 7 and 14&nbsp;days post-injury, with no change in bone formation at any time points.ConclusionsHigh-dose ALN treatment was able to prevent early trabecular bone loss and cartilage degeneration following non-invasive knee injury, but was not able to mitigate long-term joint degeneration. These data contribute to understanding the effect of bisphosphonates on the development of osteoarthritis, and may support the use of anti-resorptive drugs to prevent joint degeneration following injury, although further investigation is warranted

    Investigation of grain orientations of melt-textured HTSC with addition of uranium oxide, Y2O3 and Y2BaCuO5

    Get PDF
    Local grain orientations were studied in melt-textured YBCO samples processed with various amounts of depleted uranuim oxide (DU) and Y 2O3 by means of electron backscatter diffraction (EBSD) analysis. The addition of DU leads to the formation of Ucontaining nanoparticles (Y2Ba4CuUOx) with sizes of around 200 nm, embedded in the superconducting Y-123 matrix. The orientation of the Y 2BaCuO5 (Y-211) particles, which are also present in the YBCO bulk microstructure, is generally random as is the case in other melttextured Y-123 samples. The presence of Y-211 particles, however, also affects the orientation of the Y-123 matrix in these samples

    EBSD characterisation of Y2Ba4CuUOx phase in melttextured YBCO with addition of depleted uranium oxide

    Get PDF
    Melt-textured YBCO samples processed with added Y2O3 and depleted uranium oxide (DU) contain nano-particles, which have been identified previously as Y2Ba4CuUOx (U-411). This phase has a cubic unit cell, which is clearly distinct from the orthorhombic Y-123 and Y-211 phases within the YBCO system. In samples with a high amount of DU addition (0.8 wt-% DU), U-2411 particles have sizes between 200 nm and several νm, so identification of the Kikuchi patterns of this phase becomes possible. Together with a parallel EDX analysis, the particles embedded in the Y-123 matrix can be identified unambiguously. In this way, a three-phase EBSD scan becomes possible, allowing also the identification of nanometre-sized particles in the sample microstructure

    Growth-related profiles of remanent flux in bulk melt-textured YBaCuO crystal magnetized by pulsed fields

    Full text link
    We have studied the remanent magnetic flux distribution in bulk melt-textured YBa2Cu3O7 (YBCO) crystals after their magnetization in quasi-static and pulsed magnetic fields up to 6T. It has been shown that, provided that the magnetic pulse is sharp enough and its amplitude much exceeds the twice penetration magnetic field, the pulse magnetization technique becomes extremely sensitive to the sample inhomogeneities. Using this method with appropriate parameters of the magnetic pulse, we have particularly demonstrated that the growth of YBCO crystals in the growth sectors (GSs) responds for a macroscopic arrangement of weaks links -- they mostly appear inside of GSs, but not along the GS boundaries.Comment: 8 pages in LaTeX2e, 5 figures. Revised version, submitted to Supercond. Sci. Techno

    Pengaruh Roe, Der, Tato, Dan Per Terhadap Harga Saham Perusahaan Properti Dan Real Estate Yang Go Publik Di Bursa Efek Indonesia

    Full text link
    Investors require accurate information for making decision, such as return on equty (ROE), debt to equity ratio (DER), total assets turnover (TATO), and price earning ratio (PER). The purpose of this study is to determine the influence of ROE, DER, TATO, and PER either jointly or individually to the stock price. Population of this study is the real estate company which is go public in Indonesian Stock Exchange between 2007 – 2010 as much as 45 company. Sample of this study as much as 21 company. Methods of sample selection was done by purposive sampling with the following considerations: (1) consecutively listing between 2007 – 2010; (2) the required data is available; (3) book closing per 31 December. The study concluded that: ROE, DER, TATO, and PER jointly have significant effect on stock price (F value = 3.268 &gt; F table = 2.51 on sig. F = 0.017). The contribution of the four independent variables together to Stock Price is 16.3%, while the remaining 83.7% are affected by other variables that not examined in this study. ROE and PER individually have significant effect on stock price. DER and TATO doesnt have significant effect on stock price
    • …
    corecore