Scatter broadening of pulsars and implications on the interstellar medium turbulence

Observations reveal a uniform Kolmogorov turbulence throughout the diffuse ionized interstellar medium (ISM) and supersonic turbulence preferentially located in the Galactic plane. Correspondingly, we consider the Galactic distribution of electron density fluctuations consisting of not only a Kolmogorov density spectrum but also a short-wave-dominated density spectrum with the density structure formed at small scales due to shocks. The resulting dependence of the scatter broadening time on the dispersion measure (DM) naturally interprets the existing observational data for both low and high-DM pulsars. According to the criteria that we derive for a quantitative determination of scattering regimes over wide ranges of DMs and frequencies $\nu$, we find that the pulsars with low DMs are primarily scattered by the Kolmogorov turbulence, while those at low Galactic latitudes with high DMs undergo more enhanced scattering dominated by the supersonic turbulence, where the corresponding density spectrum has a spectral index $\approx 2.6$. Besides, by considering a volume filling factor of the density structures with the dependence on $\nu$ as $\propto \nu^{1.4}$ in the supersonic turbulence, our model can also explain the observed shallower $\nu$ scaling of the scattering time than the Kolmogorov scaling for the pulsars with relatively large DMs. The comparison between our analytical results and the scattering measurements of pulsars in turn makes a useful probe of the properties of the large-scale ISM turbulence, e.g., an injection scale of $\sim 100$ pc, and also characteristics of small-scale density structures.Comment: 11 pages, 3 figures, accepted for publication in Ap

3D stabilization-free virtual element method for linear elastic analysis

We present a first-order stabilization-free virtual element method (VEM) for three-dimensional linear elastic problems in this paper. VEM has been increasingly used in various fields of engineering, but the need of stabilization yields a method that cannot be used without care, e.g. in nonlinear engineering applications. In this work, by increasing the order of the strain model, a new virtual element formulation is constructed for three-dimensional problems that does not require any stabilization term. The core concept involves adapting the virtual element space to enable the computation of a higher-order L2 projection operator, guaranteeing an accurate representation of the element energy in terms of strain and stress. This work describes the calculation process of the original H1 projection operator and the higher-order L2 projection operator for three-dimensional problems. Eigenvalue analysis allows to derive an approximate relation between the polynomial order and the number of element vertices. Some benchmark problems illustrate the capability of the stabilization-free VEM for three-dimensional linear elastic problems

Expression And Functions Of Il-24 And Socs3 In Pseudomonas Aeruginosa Keratitis In A C57bl/6 Mouse Model

The aim of this study was to elucidate the expression and functions of interleukin (IL)-24 and suppressor of cytokine signaling 3 (SOCS3), and their regulatory relationship in C57BL/6 mouse corneas in response to Pseudomonas aeruginosa (PA) infection. Among IL-20R cytokines, only IL-24 was induced at both mRNA and protein levels by the infection, and this upregulation was dampened by flagellin pretreatment. Time course studies revealed that IL-24 expression was markedly elevated, followed by a subsidence and second elevation, a pattern shared with SOCS3 but not IL-1β or IL-6. Silencing of IL-24 enhanced S100A8/A9 expression, and suppressed SOCS3, IL-1β, IL-1RN, and MMP13 expression during an early stage of infection. Downregulation of IL-24 signaling pathway significantly reduced the severity of keratitis, bacterial burden, and neutrophil infiltration; while recombinant IL-24 exacerbated PA keratitis. Furthermore, SOCS3 knockdown impaired the control of PA keratitis. In vitro, while IL-1β induced the expression of SOCS3, IL-24, IL-1β, and IL-6, IL-24 only elicited robust expression of SOCS3 in primarily cultured human corneal epithelial cells. In conclusion, IL-24 promotes PA keratitis by inducing SOCS3 expression, resulting in the suppression of the necessary inflammatory response at an early stage of infection, and in the increased severity of PA keratitis

Identification and realization of changing production efficiency with path converged design

制度:新 ; 報告番号:甲2899号 ; 学位の種類:博士(工学) ; 授与年月日: 2009/9/15 ; 早大学位記番号:新512

Forest Biomass and Soil Carbon Stock Changes in the Delaware River Basin

Forests play an important role in the global carbon cycle. Quantifying forest biomass and soil carbon stocks and their change over time and space is important to understand forest dynamics and their feedbacks with climate change. This dissertation investigates the forest biomass and soil carbon stocks and their controlling factors in the Delaware River Basin (DRB) using a combination of field measurements and modeling. In 2001-2003, 77 forest plots in three research sites were established and their biomass was measured. In 2012-2014, 61 of these plots were revisited and forest biomass was re-measured using the same protocols. Two soil sampling methods, the Forest Inventory Analysis standard soil core method and the quantitative soil pit method, were also used to collect soil samples. Based on the results of field measurements, a process-based ecosystem model (PnET-CN) was parameterized and used to simulate the spatial distribution of forest carbon pool and fluxes in the three sites. We found that the mean biomass carbon stock in the three sites was 166.5 Mg C ha-1 and had increased by 2.35 Mg C ha-1 yr-1 and was thus a carbon sink over the past decade. The soil carbon stock to 40 cm depth was 76.6 Mg C ha-1. The accuracy of the soil core sampling method was questioned because in the surface mineral soil layer, lower bulk density, lower coarse fragment content and greater carbon concentration were measured using the core method compared to the pit method. By parameterizing the wood turnover rate, maximum photosynthesis rate and disturbance year based on field measurements, the performance of the PnET-CN model was improved in capturing the spatial variation of forest carbon dynamics. The modified model was also used in experimental scenarios, demonstrating 39% of forest carbon sequestered over the past decade could be attributed to the combined effects of elevated CO2 and nitrogen deposition. Large uncertainties in forest carbon stocks at regional scales are associated with the spatial heterogeneity of the forest. A long-term forest monitoring system combined with modelling can greatly reduce the uncertainties and increase the accuracy of our estimates of forest carbon stocks

Three essays on banking and finance in China

This thesis investigates how bank regulations and institutional reforms shape bank competition, credit supply, and loan contracts design in the context of Chinese banking market. The first chapter compares the theoretical foundations and empirical performances of commonly applied bank competition measures under China‟s binding interest rate regulations. The second chapter investigates if informational monopolies resulting from relationship lending and bank market concentration allow for rent extraction through collateral. The third chapter evaluates the effects of collateral law reform on firms‟ access to finance and credit transactions among firms.Programa Oficial de Doctorado en EconomíaPresidente: Sergio Mayordomo; Secretario: Jesús Fernández-Huertas Moraga; Vocal: Geraldo Cerqueir