Integrability of Stochastic Birth-Death processes via Differential Galois Theory

Stochastic birth-death processes are described as continuous-time Markov processes in models of population dynamics. A system of infinite, coupled ordinary differential equations (the so-called master equation) describes the time-dependence of the probability of each system state. Using a generating function, the master equation can be transformed into a partial differential equation. In this contribution we analyze the integrability of two types of stochastic birth-death processes (with polynomial birth and death rates) using standard differential Galois theory. We discuss the integrability of the PDE via a Laplace transform acting over the temporal variable. We show that the PDE is not integrable except for the (trivial) case in which rates are linear functions of the number of individuals

Nonlinear model predictive control of a passenger vehicle for automated lane changes

This article presents a nonlinear Model Predictive Control (MPC) for lane changes, based on a simplified Single Track Model (STM) of the vehicle. The STM includes the position of the vehicle in global coordinates as a state so that the position of the target lane can be specified to the MPC for reference tracking. Moreover, a constraint for maintaining a safety distance with the vehicles in the target lane is included. Simulation results show the effectiveness of the MPC in scenarios with different initial conditions that demonstrate the correct implementation of the safety distance constraint

Chaos around Holographic Regge Trajectories

Using methods of Hamiltonian dynamical systems, we show analytically that a dynamical system connected to the classical spinning string solution holographically dual to the principal Regge trajectory is non-integrable. The Regge trajectories themselves form an integrable island in the total phase space of the dynamical system. Our argument applies to any gravity background dual to confining field theories and we verify it explicitly in various supergravity backgrounds: Klebanov-Strassler, Maldacena-Nunez, Witten QCD and the AdS soliton. Having established non-integrability for this general class of supergravity backgrounds, we show explicitly by direct computation of the Poincare sections and the largest Lyapunov exponent, that such strings have chaotic motion.Comment: 28 pages, 5 figures. V3: Minor changes complying to referee's suggestions. Typos correcte

Evaluation of Soil Test Phosphorus Extractants and Tissue Analysis for Corn

The objective of this study was to evaluate the relationship of four different soil test phosphorus methods (Mehlich 3, Bray 1, Bray 2, and Haney H3A) for corn production, and determine critical P tissue concentration at different growing stages. The experiment was conducted at 12 locations, and the fertilizer treatments consisted of five phosphorus fertilizer rates applied by broadcast pre-plant. Soil samples were collected at 0- to 6-in. depth, then samples were collected before treatment application by block. Tissue samples were collected at the V6 and R1 growth stages. The relationship between the different soil test phosphorus methods and the R2 varies between 0.24–0.93. Mehlich 3 and Bray 1 have a higher correlation, and Bray 1 and Bray 2 have a lower correlation. Linear plateau determined the critical phosphorus levels for the V6 growth stage was 0.42%, and for the R1 stage was 0.22%. The relationship between the concentration at V6 and R1 was moderately correlated with R2 = 0.62, having a higher phosphorus concentration in the early stage

Early-Season Corn Response to Broadcast Pre-Plant Phosphorus Fertilizer Application

The objective of this study was to evaluate early-season corn response to different rates of preplant broadcast phosphorus fertilizer and determine the optimum levels using four different soil test methods. The study was conducted in 11 locations across Kansas in 2021. The experimental design is a randomized complete block design with four replications. Fertilizer treatment consisted of five rates of phosphorus fertilizer (0, 30, 60, 90, and 120 lb/a of P2O5). Fertilizer was applied one time by broadcast pre-plant. Soil samples were collected at 0- to 6-in. deep before treatment application, composited by blocks, and analyzed for soil test phosphorus using Mehlich 3, Haney H3A, Bray 1, and Bray 2 test methods. Whole plant sampling at V6 was collected for phosphorus uptake analysis. Results show that using early season phosphorus uptake response provided critical levels of 23 and 17 ppm of phosphorus for the Mehlich 3 and Bray 1 methods, respectively. For the Haney H3A method, the critical level was estimated at 15 ppm and for the Bray 2 method had an estimated critical value of 69 ppm. Phosphorus uptake at early season (V6) showed a significant response to broadcast phosphorus fertilization at four of eleven sites

Implementaci?n de t?cnicas gr?fico-pl?sticas como estrategia pedag?gica para el fortalecimiento de la motricidad fina en los ni?os y ni?as del nivel de preescolar.

99 p. Recurso Electr?nicoEn la formaci?n integral del ni?odesde los primeros a?os de la vida, es fundamental el desarrollo de la actividad creativa, la expresi?n gr?fico -pl?stica y la imaginaci?n, toda vez que constituye una actividad que promueve el desarrollo de la motricidad, el pensamiento cr?tico y la capacidad de proposici?n, como elementos fundamentales que le permiten al ni?o conocer, interactuar y transformar su entorno. Como parte del proceso de investigaci?n formativa que dispone el Programa de Licenciatura en Pedagog?a Infantil de la Universidad del Tolima, se llev? a cabo un proyecto enfocado hacia la implementaci?n de una propuesta pedag?gica que promueva el dise?o y la ejecuci?n de t?cnicas gr?fico? pl?sticascomo estrategia para el fortalecimiento de la motricidad fina en los ni?os y ni?as en nivel preescolar. El proyecto parte de la necesidad de permitir a los ni?os del nivel preescolar de la Instituci?n Educativa T?cnica La Sagrada Familia - Sede Versallesacceder a otros lenguajes a trav?s de actividades de su inter?s y agrado como espintar, modelar,rasgar, recortar, ensartar o dibujar, que se convierten en estrategias estimuladoras de su potencial creativo y creador, y a la vez fortalecen habilidades que son fundamentales para un adecuado desarrollo y desempe?o de su motricidad fina.Atrav?s del Proyecto Pedag?gico de Aula: Manitos creativas y juguetonas, se logra apropiar por los docentes, los padres de familia y los ni?os la expresi?n gr?fico ? pl?stica como una estrategia que fortalece la motricidad fina, a la vez que ofrece la instalaci?n de ambientes propicios para el aprendizaje desde el espacio preescolar. Palabras claves: Gr?fico - pl?stico, arte, motricidad fina, aprendizaje, expresi?n creativa.In the integral formation of the child from the first years of life, the development of the creative activity, the graphic expression - plastic and the imagination, since it constitutes an activity that promotes the development of the motor, critical thinking and the capacity for proposition, as fundamental elements that allow the child to know, interact and transform their environment. As part of the process of formative research provided by the Graduate Program in Pedagogy for Children at the University of Tolima, a project was carried out focusing on the implementation of a pedagogical proposal that promotes the design and execution of graphic techniques such as strategy for the strengthening of fine motor skills in preschool children. The project starts from the need to allow children of the pre-school level of the Educational Institution The Sagrada Familia - Versailles Headquarters to access other languages through activities of their interest and enjoyment such as painting, modeling, ripping, trimming, strumming or drawing , Which become strategies that stimulate their creative and creative potential, and at the same time strengthen skills that are fundamental for an adequate development and performance of their fine motor skills.Through the Pedagogical Project of Classroom: Creative and playful hands, it is possible to appropriate for teachers, parents and children the graphic - plastic expression as a strategy that strengthens fine motor skills, while offering the installation of environments Conducive to learning from preschool. Key Words:Graphic - plastic, art, fine motor skills, learning, creative expression

Cost-effectiveness of AQP4 antibody detection with cell-based assay compared with elisa for devic disease diagnosis in Colombia

Q1Q1A44Objectives Neuromyelitis optica (NMO) or Devic disease is a rare chronic condition characterized by demyelinating lesions in the central nervous system. The aim of this study was to evaluate cost-effectiveness of the detection of antibodies against the protein aquaporin water channel 4 (AQP4) with cell-based assay (CBA), compared with ELISA, for the diagnosis of NMO in Colombia. Methods A decision tree model was constructed to compare costs, correctly diagnosed cases and relapses averted in patients with clinical suspicion of NMO, that were subjected to diagnostic tests for the detection of AQP4 antibodies. The analysis was undertaken from a third-party payer perspective, one year time horizon (first year with the disease) taking all costs for treatment and relapses, in 2014 Colombian pesos, from official published prices (1 USD = 2,033 COP). Since the CBA kit is not available in Colombia (currently samples are processed abroad), the price was obtained from the manufacturer and set in a national laboratory. Clinical variables were from a systematic literature review. Univariate and probabilistic sensitivity analyses (a Monte Carlo simulating a cohort of 1000 patients) were conducted. Results Identification of AQP4 antibodies with CBA is a dominant strategy: more effective (855 correctly diagnosed patients compared with 765 detected by ELISA, and 130 avoided relapses), and less costly, with expected yearly costs per correctly diagnosed Devic patient of USD $14,658 compared with$15,614 for ELISA. Using CBA may represent savings in terms of reduced costs of treating disease and relapse with hospitalization. Conclusions AQP4 antibody identification by the CBA method is a cost-saving diagnostic test, dominant over the ELISA method

Sensitivity analysis in optimized parametric curve fitting

Purpose – Curve fitting from unordered noisy point samples is needed for surface reconstruction in many applications -- In the literature, several approaches have been proposed to solve this problem -- However, previous works lack formal characterization of the curve fitting problem and assessment on the effect of several parameters (i.e. scalars that remain constant in the optimization problem), such as control points number (m), curve degree (b), knot vector composition (U), norm degree (k), and point sample size (r) on the optimized curve reconstruction measured by a penalty function (f) -- The paper aims to discuss these issues -- Design/methodology/approach - A numerical sensitivity analysis of the effect of m, b, k and r on f and a characterization of the fitting procedure from the mathematical viewpoint are performed -- Also, the spectral (frequency) analysis of the derivative of the angle of the fitted curve with respect to u as a means to detect spurious curls and peaks is explored -- Findings - It is more effective to find optimum values for m than k or b in order to obtain good results because the topological faithfulness of the resulting curve strongly depends on m -- Furthermore, when an exaggerate number of control points is used the resulting curve presents spurious curls and peaks -- The authors were able to detect the presence of such spurious features with spectral analysis -- Also, the authors found that the method for curve fitting is robust to significant decimation of the point sample -- Research limitations/implications - The authors have addressed important voids of previous works in this field -- The authors determined, among the curve fitting parameters m, b and k, which of them influenced the most the results and how -- Also, the authors performed a characterization of the curve fitting problem from the optimization perspective -- And finally, the authors devised a method to detect spurious features in the fitting curve -- Practical implications – This paper provides a methodology to select the important tuning parameters in a formal manner -- Originality/value - Up to the best of the knowledge, no previous work has been conducted in the formal mathematical evaluation of the sensitivity of the goodness of the curve fit with respect to different possible tuning parameters (curve degree, number of control points, norm degree, etc.

Finding Respondents from Minority Groups

The recruitment of respondents belonging to ethnic minorities poses important challenges in social and health research. This paper reflects on the enablers and barriers to recruitment that we encountered in our research work with persons belonging to ethnic minorities. Additionally, we applied the Matching Model of Recruitment, a theoretical framework concerning minority recruitment, to guide our reflection. We also explored its applicability as a research design tool. In assessing our research experience, we learned that minority recruitment in social and health research is influenced by the social context of all key players involved in the research. Also, there are enablers and barriers within that social context facilitating or delaying the recruitment process. The main enablers to recruit respondents belonging to ethnic minorities include working with community agencies and gatekeepers who share a common vision with researchers and the latter’s ability to gain the trust of potential respondents. The main barriers include demanding too much from these same community agencies and gatekeepers and ignoring factors that could delay the completion of the research. Although we found the Matching Model of Recruitment to be an effective tool in assessing the processes of recruiting respondents belonging to ethnic minorities, further empirical research is needed to explore its usefulness during the research planning phase

Geodesic-based manifold learning for parameterization of triangular meshes

Reverse Engineering (RE) requires representing with free forms (NURBS, Spline, Bézier) a real surface which has been pointsampled -- To serve this purpose, we have implemented an algorithm that minimizes the accumulated distance between the free form and the (noisy) point sample -- We use a dualdistance calculation point to / from surfaces, which discourages the forming of outliers and artifacts -- This algorithm seeks a minimum in a function that represents the fitting error, by using as tuning variable the control polyhedron for the free form -- The topology (rows, columns) and geometry of the control polyhedron are determined by alternative geodesicbased dimensionality reduction methods: (a) graphapproximated geodesics (Isomap), or (b) PL orthogonal geodesic grids -- We assume the existence of a triangular mesh of the point sample (a reasonable expectation in current RE) -- A bijective composition mapping allows to estimate a size of the control polyhedrons favorable to uniformspeed parameterizations -- Our results show that orthogonal geodesic grids is a direct and intuitive parameterization method, which requires more exploration for irregular triangle meshes -- Isomap gives a usable initial parameterization whenever the graph approximation of geodesics on be faithful -- These initial guesses, in turn, produce efficient free form optimization processes with minimal errors -- Future work is required in further exploiting the usual triangular mesh underlying the point sample for (a) enhancing the segmentation of the point set into faces, and (b) using a more accurate approximation of the geodesic distances within , which would benefit its dimensionality reductio