Geometric Integration of Hamiltonian Systems Perturbed by Rayleigh Damping

Explicit and semi-explicit geometric integration schemes for dissipative perturbations of Hamiltonian systems are analyzed. The dissipation is characterized by a small parameter $\epsilon$, and the schemes under study preserve the symplectic structure in the case $\epsilon=0$. In the case $0<\epsilon\ll 1$ the energy dissipation rate is shown to be asymptotically correct by backward error analysis. Theoretical results on monotone decrease of the modified Hamiltonian function for small enough step sizes are given. Further, an analysis proving near conservation of relative equilibria for small enough step sizes is conducted. Numerical examples, verifying the analyses, are given for a planar pendulum and an elastic 3--D pendulum. The results are superior in comparison with a conventional explicit Runge-Kutta method of the same order

Fronts dynamics in the presence of spatio-temporal structured noises

Front dynamics modeled by a reaction-diffusion equation are studied under the influence of spatio-temporal structured noises. An effective deterministic model is analytical derived where the noise parameters, intensity, correlation time and correlation length appear explicitely. The different effects of these parameters are discussed for the Ginzburg-Landau and Schl\"ogl models. We obtain an analytical expression for the front velocity as a function of the noise parameters. Numerical simulations results are in a good agreement with the theoretical predictions.Comment: 11 pages, 6 figures; REVTEX; to be published in Phys.Rev.E, july 200

Bayesian analysis of a disability model for lung cancer survival

Bayesian reasoning, survival analysis and multi-state models are used to assess survival times for Stage IV non-small-cell lung cancer patients and the evolution of the disease over time. Bayesian estimation is done using minimum informative priors for the Weibull regression survival model, leading to an automatic inferential procedure. Markov chain Monte Carlo methods have been used for approximating posterior distributions and the Bayesian information criterion has been considered for covariate selection. In particular, the posterior distribution of the transition probabilities, resulting from the multi-state model, constitutes a very interesting tool which could be useful to help oncologists and patients make efficient and effective decisions.This study has been partially supported by the Ministerio de Ciencia e Innovación [grant number MTM2010- 19528], Mutua Madrileña [grant AP75942010], Ministero dell'Istruzione, dell'Universitá e della Ricerca of Italy and the visiting professor program of the Regione Autonoma della Sardegna

Kinematic reduction of reaction-diffusion fronts with multiplicative noise: Derivation of stochastic sharp-interface equations

We study the dynamics of generic reaction-diffusion fronts, including pulses and chemical waves, in the presence of multiplicative noise. We discuss the connection between the reaction-diffusion Langevin-like field equations and the kinematic (eikonal) description in terms of a stochastic moving-boundary or sharp-interface approximation. We find that the effective noise is additive and we relate its strength to the noise parameters in the original field equations, to first order in noise strength, but including a partial resummation to all orders which captures the singular dependence on the microscopic cutoff associated to the spatial correlation of the noise. This dependence is essential for a quantitative and qualitative understanding of fluctuating fronts, affecting both scaling properties and nonuniversal quantities. Our results predict phenomena such as the shift of the transition point between the pushed and pulled regimes of front propagation, in terms of the noise parameters, and the corresponding transition to a non-KPZ universality class. We assess the quantitative validity of the results in several examples including equilibrium fluctuations, kinetic roughening, and the noise-induced pushed-pulled transition, which is predicted and observed for the first time. The analytical predictions are successfully tested against rigorous results and show excellent agreement with numerical simulations of reaction-diffusion field equations with multiplicative noise.Comment: 17 pages, 6 figure

Bayesian estimation of incomplete data using conditionally specified priors

In this paper, a class of conjugate prior for estimating incomplete count data based on a broad class of conjugate prior distributions is presented. The new class of prior distributions arises from a conditional perspective, making use of the conditional specification methodology and can be considered as the generalisation of the form of prior distributions that have been used previously in the estimation of in- complete count data well. Finally, some examples of simulated and real data are given

Co-rotational Formulation for Bonded Joint Finite Elements

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97052/1/AIAA2012-1449.pd

Heavy ion beam measurement of the hydration of cementitious materials

The setting and development of strength of Portland cement concrete depends upon the reaction of water with various phases in the Portland cement. Nuclear resonance reaction analysis (NRRA) involving the 1H(15N,α,γ)12C reaction has been applied to measure the hydrogen depth profile in the few 100 nm thick surface layer that controls the early stage of the reaction. Specific topics that have been investigated include the reactivity of individual cementitious phases and the effects of accelerators and retarders

Global profiling of alternative RNA splicing events provides insights into molecular differences between various types of hepatocellular carcinoma

Protein families encoded by transcripts that are differentially spliced in various types of HCC. Table S2. Bioinformatical prediction of functional changes caused by some of ASEs identified. Table S3. List of tumor suppressors for which AS is dysregulated in various types of HCC. Table S4. List of oncogenes for which AS is dysregulated in various types of HCC. Table S5. List of kinases for which AS is dysregulated in various types of HCC. Table S6. List of transcription factors for which AS is dysregulated in various types of HCC. Table S7. List of genes for which AS is dysregulated in all types of HCC. Table S8. List of genes uniquely dysregulated in HBV-associated HCC. Table S9. List of genes uniquely dysregulated in HCV-associated HCC. Table S10. List of genes uniquely dysregulated in HBV&HCV-associated HCC. Table S11. List of genes uniquely dysregulated in virus-free HCC. Figure S1. Characterization of splicing mysregulation in HCC. Figure S2. Characterization of ASEs that are modified in HBV- and HCV-associated HCC. Figure S3. AS modifications in transcripts encoded by kinases and transcriptions factores in HBV- and HCV-associated HCC. Figure S4. Global profiling of ASE modifications in both HBV&HCV-associated HCC and virus-free-associated HCC. Figure S5. RNA splicing factors in HCC. Figure S6. Modifications to AS of 96 transcripts in response to knockdown of splicing factors with specific siRNAs (PDF 6675 kb

Overdamped sine-Gordon kink in a thermal bath

We study the sine-Gordon kink diffusion at finite temperature in the overdamped limit. By means of a general perturbative approach, we calculate the first- and second-order (in temperature) contributions to the diffusion coefficient. We compare our analytical predictions with numerical simulations. The good agreement allows us to conclude that, up to temperatures where kink-antikink nucleation processes cannot be neglected, a diffusion constant linear and quadratic in temperature gives a very accurate description of the diffusive motion of the kink. The quadratic temperature dependence is shown to stem from the interaction with the phonons. In addition, we calculate and compute the average value $$ of the wave function as a function of time and show that its width grows with $\sqrt{t}$. We discuss the interpretation of this finding and show that it arises from the dispersion of the kink center positions of individual realizations which all keep their width.Comment: REVTeX, 12 pages, 10 figures, to appear in Phys Rev

Estilos de aprendizaje y evaluación formativa: Estudio con universitarios de Educación Física chilenos

Assessment contributes to students learning. Formative assessment is a useful strategy of the initial teacher training. Perceptions about the assessment of Chilean university Physical Education students (n = 95), depending on their learning style, gender and academic course were analyzed. The Learning Styles Questionnaire and the Spanish version of the Assessment Experience Questionnaire were used. The results showed negative perceptions about the assessment process. Significant differences were observed in the perceptions about the use of feedback depending on the learning style of the students (F = 1.062, p =. 004). Significant differences were observed in the perception about the amount of effort (F = 5.888, p =. 000), the suitability of the evaluation (F = 3.282, p =. 015) and the shallow approach to the learning (F = 5.472, p =. 001), depending on the academic course. Gender was not a determinant of perceptions. The findings suggest the use of traditional procedures of assessment (summative assessment) with the students. On the other hand, findings show the influence of learning stylesand the academic course on student perceptionsand learning styles and feedback. This information contributes to a deeper understanding of the learning mode of the students according to their characteristics and context.La evaluación contribuye a la formación del aprendizaje, facilitando el avance del estudiante. La evaluación formativa se presenta como una estrategia eficaz dentro de la formación inicial docente. Se analizaron las percepciones sobre la evaluación de universitarios de Educación Física chilenos (n = 95), en función de su estilo de aprendizaje, género y curso académico. Se utilizaron el Cuestionario de Estilos de Aprendizaje y la versión en castellano del Assessment Experience Questionnaire. Los resultados mostraron percepciones negativas sobre el proceso evaluativo. Se observaron diferencias significativas en las percepciones sobre el uso del feedback en función del estilo de aprendizaje (F= 1.062, p = .004). Se observaron diferencias significativas en la percepción de la cantidad de esfuerzo (F= 5.888, p = .000), la adecuación de la evaluación (F= 3.282, p = .015)y la aproximación superficial al aprendizaje (F= 5.472, p = .001), en función del curso académico. El género no fue determinante de las percepciones. Los hallazgos sugieren la utilización de procedimientos de evaluación tradicional con los encuestados. Se encontraron relaciones entre el estilo de enseñanza y el feedback, y entre el curso académico y las percepciones de evaluación. Esta información contribuye a un entendimiento más profundo del modo de aprender de los estudiantes en función de sus características y contexto