Intersections of Quadrics, Moment-angle Manifolds and Connected Sums

The topology of the intersection of two real homogeneous coaxial quadrics was studied by the second author who showed that its intersection with the unit sphere is in most cases diffeomorphic to a connected sum of sphere products. Combining that approach with a recent one (due to Antony Bahri, Martin Bendersky, Fred Cohen and the first author) we study here the intersections of k>2 quadrics and we identify very general families of such manifolds that are diffeomorphic to connected sums of sphere products. These include those moment-angle manifolds for which the result was conjectured by Frederic Bosio and Laurent Meersseman. As a byproduct, a simpler and neater proof of the result for the case k=2 is obtained. Two new sections contain results not included in the first version of this article: Section 2 describes the topological change on the manifolds after the operations of cutting off a vertex or an edge of the associated polytope, which can be combined in a special way with the previos results to produce new infinite families of manifolds that are connected sums of sphere products. In other cases we get slightly more complicated manifolds: with this we solve another question by Bosio-Meersseman about the manifold associated to the truncated cube. In Section 3 we use this to show that the known rules for the cohomology product of a moment-angle manifold have to be drastically modified in the general situation. We state the modified rule, but leave the details of this for another publication. Section 0 recalls known definitions and results and in section 2.1 some elementary topological constructions are defined and explored. In the Appendix we state and prove some results about specific differentiable manifolds, which are used in sections 1 and 2.Comment: We have included many clarifying suggestions and minor corrections from some colleagues who read the manuscript carefully. The only change in content from the previous version is the suppression a special case (item 3) of Theorem 1.3 because we have not been able to fill in the details of any of the known sketched proofs (including ours

Recursive formulas for Welschinger invariants of the projective plane

Welschinger invariants of the real projective plane can be computed via the enumeration of enriched graphs, called marked floor diagrams. By a purely combinatorial study of these objects, we prove a Caporaso-Harris type formula which allows one to compute Welschinger invariants for configurations of points with any number of complex conjugated points.Comment: 18 pages, 2 figure

Incidencias de las estrategias de enseñanza en la comprensión lectora de textos literarios en la disciplina de Lengua y Literatura en estudiantes de octavo grado A turno matutino , Instituto Sor Oliva Lombardi, Municipio Rio Blanco, Departamento Matagalpa, segundo semestre 2016

La presente investigación trata sobre la comprensión lectora en la enseñanza aprendizaje de la disciplina de Lengua y Literatura en la Educación Secundaria, teniendo como objetivo principal “Analizar la comprensión lectora en la enseñanza aprendizaje de la disciplina de Lengua y Literatura con los estudiantes de octavo grado A del Instituto Sor Oliva Lombardi, municipio de Rio Blanco, Departamento Matagalpa, segundo semestre 2016”. Se admite su importancia ya que favorecen el conocimiento de los aprendices para desarrollar en ellos la comprensión lectora, implementando las diferentes estrategias de enseñanza en el análisis de los textos, que sustenta el desarrollo del saber, como una de las competencias necesarias para la inserción profesional de calidad. El tipo de estudio de esta investigación es de carácter descriptivo debido a que cada dato numérico se va describiendo según el evento analizado, así como el enfoque cuantitativo, dedicado a recoger, procesar y analizar datos numéricos. En esta investigación se utiliza distintos instrumentos de recolección de información como: encuesta aplicada a estudiantes, entrevista dirigida a docente y a director, que imparte clase al año descrito anteriormente, también se aplicó una guía de observación durante todo el desarrollo de una clase la cual contenía varios aspectos a observar relaciona con el tema en investigación. Las principales conclusiones son: Se logró determinar estrategias de enseñanza en la comprensión lectora. Se identificó el proceso de comprensión lectora en lectura de textos literarios ya que es una causa encontrada en los estudiantes al no aplicar y poner en práctica este proceso, los discentes en el análisis de textos no aplica la estrategia correspondiente para la interpretación del mismo. Palabras Claves: Estrategias, comprensión, textos, estudiante, enseñanz

Puiseux power series solutions for systems of equations

We give an algorithm to compute term-by-term multivariate Puiseux series exapansions of series arising as local parametrizations of zeroes of systems of algebraic equations at singular points. The algorithm is an extension of Newton polygon to the tropical variety of the ideal generated by the system

Microelectronic cmos implementation of a machine learning technique for sensor calibration

An integrated machine-learning based adaptive circuit for sensor calibration implemented in standard 0.18μm CMOS technology with 1.8V power supply is presented in this paper. In addition to linearizing the device response, the proposed system is also capable to correct offset and gain errors. The building blocks conforming the adaptive system are designed and experimentally characterized to generate numerical high-level models which are used to verify the proper performance of each analog block within a defined multilayer perceptron architecture. The network weights, obtained from the learning phase, are stored in a microcontroller EEPROM memory, and then loaded into each of the registers of the proposed integrated prototype. In order to verify the proposed system performance, the non-linear characteristic of a thermistor is compensated as an application example, achieving a relative error er below 3% within an input span of 130°C, which is almost 6 times less than the uncorrected response. The power consumption of the whole system is 1.4mW and it has an active area of 0.86mm 2 . The digital programmability of the network weights provides flexibility when a sensor change is required

Meaning of work and personal protective factors among palliative care professionals

Objective.—Healthcare professionals who work in palliative care units face stressful life events on a daily basis, most notably death. For this reason, these professionals must be equipped with the necessary protective resources to help them cope with professional and personal burnout. Despite the well-recognized importance of the construct “meaning of work,” the role of this construct and its relationship with other variables is not well-understood. Our objective is to develop and evaluate a model that examines the mediating role of the meaning of work in a multidisciplinary group of palliative care professionals. Using this model, we sought to assess the relationships between meaning of work, perceived stress, personal protective factors (optimism, self-esteem, life satisfaction, personal growth, subjective vitality), and sociodemographic variables. Method.—Professionals (n = 189) from a wide range of disciplines (physicians, psychologists, nurses, social workers, nursing assistants, physical therapists, and chaplains) working in palliative care units at hospitals in Madrid and the Balearic Islands were recruited. Sociodemographic variables were collected and recorded. The following questionnaires were administered: Meaning of Work Questionnaire, Perceived Stress Questionnaire, Life Orientation Test-Revised, Satisfaction with Life Scale, Subjective Vitality Scale, Rosenberg Self-Esteem Scale, and the Personal Growth Scale. Result.—The explanatory value of the model was high, explaining 49.5% of the variance of life satisfaction, 43% of subjective vitality, and 36% of personal growth. The main findings of this study were as follow: (1) meaning of work and perceived stress were negatively correlated; (2) optimism and self-esteem mediated the effect of stress on the meaning attached to work among palliative care professionals; (3) the meaning of work mediated the effect of stress on subjective vitality, personal growth, and life satisfaction; and (4) vitality and personal growth directly influenced life satisfaction. Significance of results.—The proposed model showed a high explanatory value for the meaning professionals give to their work and also for perceived stress, personal protective factors, and sociodemographic variables. Our findings could have highly relevant practical implications for designing programs to promote the psychological well-being of healthcare professionals

Toral rank conjecture for moment-angle complexes

We consider an operation K \to L(K) on the set of simplicial complexes, which we call the "doubling operation". This combinatorial operation has been recently brought into toric topology by the work of Bahri, Bendersky, Cohen and Gitler on generalised moment-angle complexes (also known as K-powers). The crucial property of the doubling operation is that the moment-angle complex Z_K can be identified with the real moment-angle complex RZ_L(K) for the double L(K). As an application we prove the toral rank conjecture for Z_K by estimating the lower bound of the cohomology rank (with rational coefficients) of real moment-angle complexes RZ_K$. This paper extends the results of our previous work, where the doubling operation for polytopes was used to prove the toral rank conjecture for moment-angle manifolds.Comment: 4 pages, new references and credits adde

High-Linearity Self-Biased CMOS Current Buffer

A highly linear fully self-biased class AB current buffer designed in a standard 0.18 mu m CMOS process with 1.8 V power supply is presented in this paper. It is a simple structure that, with a static power consumption of 48 mu W, features an input resistance as low as 89 Omega, high accuracy in the input-output current ratio and total harmonic distortion (THD) figures lower than -60 dB at 30 mu A amplitude signal and 1 kHz frequency. Robustness was proved through Monte Carlo and corner simulations, and finally validated through experimental measurements, showing that the proposed configuration is a suitable choice for high performance low voltage low power applications