Generalized gamma approximation with rates for urns, walks and trees

We study a new class of time inhomogeneous P\'olya-type urn schemes and give optimal rates of convergence for the distribution of the properly scaled number of balls of a given color to nearly the full class of generalized gamma distributions with integer parameters, a class which includes the Rayleigh, half-normal and gamma distributions. Our main tool is Stein's method combined with characterizing the generalized gamma limiting distributions as fixed points of distributional transformations related to the equilibrium distributional transformation from renewal theory. We identify special cases of these urn models in recursive constructions of random walk paths and trees, yielding rates of convergence for local time and height statistics of simple random walk paths, as well as for the size of random subtrees of uniformly random binary and plane trees.Comment: Published at http://dx.doi.org/10.1214/15-AOP1010 in the Annals of Probability (http://www.imstat.org/aop/) by the Institute of Mathematical Statistics (http://www.imstat.org

Total variation error bounds for geometric approximation

We develop a new formulation of Stein's method to obtain computable upper bounds on the total variation distance between the geometric distribution and a distribution of interest. Our framework reduces the problem to the construction of a coupling between the original distribution and the "discrete equilibrium" distribution from renewal theory. We illustrate the approach in four non-trivial examples: the geometric sum of independent, non-negative, integer-valued random variables having common mean, the generation size of the critical Galton-Watson process conditioned on non-extinction, the in-degree of a randomly chosen node in the uniform attachment random graph model and the total degree of both a fixed and randomly chosen node in the preferential attachment random graph model.Comment: Published in at http://dx.doi.org/10.3150/11-BEJ406 the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm

Production and characterization of Al-BN composite materials using by powder metallurgy

ArticleAluminum matrix composites containing 3, 6, 9, 12 and15% BN has been fabricated by conventional microwave sintering at 550 °C temperature. Compounds formation between Al and BN powders is observed after sintering under Ar shroud. XRD, SEM (Scanning Electron Microscope), mechanical testing and measurements were employed to characterize the properties of Al + BN composite. Exper imental results suggest that the best properties as hardness 42, 62 HV were obtained for Al+12% BN composite

Endovascular Cure of a Locked-In Patient

We report the case of a 60 year-old right-handed gentleman who became acutely “Locked-In” several days after a lower extremity orthopedic procedure. He underwent emergent endovascular treatment and had complete resolution of his neurologic findings except for mild dysarthria and dysphagia. Endovascular intervention for posterior circulation thrombosis is highly effective when patients are treated within 24 hours

Nonequilibrium phase transitions and stationary state solutions of a three-dimensional random-field Ising model under a time dependent periodic external field

Nonequilibrium behavior and dynamic phase transition properties of a kinetic Ising model under the influence of periodically oscillating random-fields have been analyzed within the framework of effective field theory (EFT) based on a decoupling approximation (DA). Dynamic equation of motion has been solved for a simple cubic lattice ($q=6$) by utilizing a Glauber type stochastic process. Amplitude of the sinusoidally oscillating magnetic field is randomly distributed on the lattice sites according to bimodal and trimodal distribution functions. For a bimodal type of amplitude distribution, it is found in the high frequency regime that the dynamic phase diagrams of the system in temperature versus field amplitude plane resemble the corresponding phase diagrams of pure kinetic Ising model. Our numerical results indicate that for a bimodal distribution, both in the low and high frequency regimes, the dynamic phase diagrams always exhibit a coexistence region in which the stationary state (ferro or para) of the system is completely dependent on the initial conditions whereas for a trimodal distribution, coexistence region disappears depending on the values of system parameters.Comment: 11 pages, 11 figure

Digitizing Products Towards Platforms: The Case of Vehicle Motion System

The development of digital product platforms is a prevailing trend in many industries. As firms incorporate digital technologies into established product categories, they need to manage tensions on multiple organizational layers including strategy, technology and structure. Recent findings suggest that tensions are most likely to be managed by creating resource and coordination flexibility. This paper reports a longitudinal case study of developing a digital product platform. By drawing on organizational ambidexterity theory, we identify four mechanisms—re-scripting, centralizing-re-directing and decoupling—through which the firm creates resource and coordination flexibility. The resulting resource and coordination flexibility in turn lead to the transformation of the firm’s strategy, technology and internal structure. The contribution of this study is in adopting an internal perspective and a bottom-up approach which help to theorize the evolution of digitized products into digital product platforms in an emergent way

Performance of Preload on Cohesionless Soils

Common occurrence of loose normally consolidated fine sands and silts extending to considerable depths necessitates the utilization of ground improvement techniques along the coasts of Arabian Peninsula. In the case considered, the soil profile consisted of twenty meter thick compressible sands, and preloading technique was suggested to stabilize the foundation soil. The paper presents the performance of the preloading and the level of soil improvement achieved. The observed settlements and settlement-time behaviour are compared with the values estimated from various methods. The soil parameters back calculated from measured field behaviour are reported