1,447 research outputs found

    GG-odometers and their almost 1-1 extensions

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    In this paper we recall the concepts of GG-odometer and GG-subodometer for GG-actions, where GG is a discrete finitely generated group, which generalize the notion of odometer in the case G=\ZZ. We characterize the GG-regularly recurrent systems as the minimal almost 1-1 extensions of subodometers, from which we deduce that the family of the GG-Toeplitz subshifts coincides with the family of the minimal symbolic almost 1-1 extensions of subodometers.Comment: 18 page

    Pipe joints reinforced in place with fitted aluminum sleeves

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    Installation of an aluminum sleeve, using specially designed tools, reinforces solder- sealed ferrule joints in installed small-diameter aluminum tubing. Tubing joints reinforced by this method withstand considerable torsional tensional, and vibrational stresses at moderately elevated temperatures

    Importance of Grief and Loss Support

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    The capstone was implemented at the Safety Nest, a wellness center that provides socio-emotional and mental health services to all students within Everett Alvarez High School through the Positive Behavioral Interventions and Supports multi-tiered system. The school serves 2,664 students; 90.2% of Hispanic/Latino ethnicity, and it is part of the Salinas Union High School District. The social problem addressed by the project is that “There are too many high school students in California experiencing emotional distress, which can result in academic failure, substance use, or suicide”. The project consisted of collaborating with the NEST’s Behavioral Intervention Specialist to implement an eight-week long Grief/Loss Counseling group for EAHS students who have experienced a recent death/loss of a loved one. The group provides a safe space to support students experiencing grief/bereavement, learn about grief, coping skills, and how to express their emotions in healthy/constructive ways in order for the healing process to begin. The positive experience from the groups suggests the NEST continues to facilitate the Grief/Loss Counseling group through the practice of Ligia M. Houben’s book, “Counseling Hispanics Through Loss, Grief, and Bereavement: A guide for mental health professionals.

    Quantum Gowdy T3T^3 Model: Schrodinger Representation with Unitary Dynamics

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    The linearly polarized Gowdy T3T^3 model is paradigmatic for studying technical and conceptual issues in the quest for a quantum theory of gravity since, after a suitable and almost complete gauge fixing, it becomes an exactly soluble midisuperspace model. Recently, a new quantization of the model, possessing desired features such as a unitary implementation of the gauge group and of the time evolution, has been put forward and proven to be essentially unique. An appropriate setting for making contact with other approaches to canonical quantum gravity is provided by the Schr\"odinger representation, where states are functionals on the configuration space of the theory. Here we construct this functional description, analyze the time evolution in this context and show that it is also unitary when restricted to physical states, i.e. states which are solutions to the remaining constraint of the theory.Comment: 21 pages, version accepted for publication in Physical Review

    Determination of biosorption mechanism in biomass of agave, using spectroscopic and microscopic techniques for the purification of contaminated water

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    [Abstract] Lead (Pb2+) and copper (Cu2+) are polluting metals due to their toxicity; however, the extraction of these metals is essential for economic development, so it is important to look for efficient and low-cost alternatives that can remove heavy metals from the various bodies of water. One of the alternatives used in this work is biosorption, for which an agroindustrial waste (epidermis from Agave atrovirens) was used to evaluate the affinity of removal of lead and copper in aqueous solutions; in addition, spectroscopy and microscopy techniques were used to elucidate and corroborate the removal and affinity capacity of the agave epidermis for both metals studied. The optimal pH value for the removal of both metals was 3. The adsorption isotherms yielded a qmax of 25.7 and 8.6 mg/g for lead and copper, respectively. Adjusting to the Langmuir-Freundlich model, the adsorption kinetics were pseudo-second order, and it was found that the equilibrium time was at 140 min. The spectroscopy and microscopy analyses corroborated the affinity between metals and functional groups of the agave, as well as with the elemental analysis, which reported 17.38% of lead and 4.25% of copper.[Resumen] El plomo (Pb2+) y el cobre (Cu2+) son metales contaminantes debido a su toxicidad; sin embargo, la extracción de estos metales es indispensable para el desarrollo económico, por lo que es importante buscar alternativas eficientes y de bajo costo que puedan remover metales pesados de los diversos cuerpos de agua. Una de las alternativas utilizadas en este trabajo es la biosorción, para la cual se utilizó un residuo agroindustrial (epidermis de Agave atrovirens), para evaluar la afinidad de remoción del plomo y cobre en soluciones acuosas; adicionalmente, se emplearon técnicas de espesctroscopía y microscopía que permitieron elucidar y corroborar la capacidad de remoción y afinidad que tuvo la epidermis de A. atrovirens para ambos metales estudiados. El valor óptimo de pH para la remoción de ambos metales fue 3. Las isotermas de adsorción arrojaron una qmax de 25.7 y 8.6 mg/g para el plomo y cobre, respectivamente. Ajustando al modelo de Langmuir-Freundlich, las cinéticas de adsorción resultaron de pseudo-segundo orden, se encontró que el tiempo de equilibrio es a los 140 min. El análisis espectroscópico y microscópico, corroboró la afinidad entre metales y grupos funcionales del agave, así como con el análisis elemental, el cual reportó 17.38% de plomo y 4.25% de cobre

    Fock quantization of a scalar field with time dependent mass on the three-sphere: unitarity and uniqueness

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    We study the Fock description of a quantum free field on the three-sphere with a mass that depends explicitly on time, also interpretable as an explicitly time dependent quadratic potential. We show that, under quite mild restrictions on the time dependence of the mass, the specific Fock representation of the canonical commutation relations which is naturally associated with a massless free field provides a unitary dynamics even when the time varying mass is present. Moreover, we demonstrate that this Fock representation is the only acceptable one, up to unitary equivalence, if the vacuum has to be SO(4)-invariant (i.e., invariant under the symmetries of the field equation) and the dynamics is required to be unitary. In particular, the analysis and uniqueness of the quantization can be applied to the treatment of cosmological perturbations around Friedmann-Robertson-Walker spacetimes with the spatial topology of the three-sphere, like e.g. for gravitational waves (tensor perturbations). In addition, we analyze the extension of our results to free fields with a time dependent mass defined on other compact spatial manifolds. We prove the uniqueness of the Fock representation in the case of a two-sphere as well, and discuss the case of a three-torus.Comment: 30 page

    Regression with Linear Factored Functions

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    Many applications that use empirically estimated functions face a curse of dimensionality, because the integrals over most function classes must be approximated by sampling. This paper introduces a novel regression-algorithm that learns linear factored functions (LFF). This class of functions has structural properties that allow to analytically solve certain integrals and to calculate point-wise products. Applications like belief propagation and reinforcement learning can exploit these properties to break the curse and speed up computation. We derive a regularized greedy optimization scheme, that learns factored basis functions during training. The novel regression algorithm performs competitively to Gaussian processes on benchmark tasks, and the learned LFF functions are with 4-9 factored basis functions on average very compact.Comment: Under review as conference paper at ECML/PKDD 201

    Learning Disabilities in Children with Autism

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    Children with autism spectrum disorders often present signs of cognitive strategies that are not within the expected developmental profile. Therefore, it should be expected that the learning process of children with this disorder should be the focus of several studies regarding schooling and literacy. Unfortunately, that is not the real situation. In this chapter, the authors propose to present an overview of the available literature about learning, reading, and literacy in children with the autism spectrum disorders and report results of studies about the association between executive functions and reading abilities in children with autism spectrum disorders that attend to regular and special schools in Brazil

    Modelling of Surfaces of Engineering Products on the Basis of Array of Points

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    The method of designing elements of the surfaces\u27 frames based on array of points is suggested in the work. Elements of frames are contours that are received via interpolation of sets of points, which are selected from the initial array of points. The algorithms have been developed for design plane and spatial contours that represent the curves with specified geometrical properties with prescribed accuracy. Formed contours are used as elements of «Profile» and «Guide Curves» at forming the model of surface by means of function of «Lofted Surface» in CAD system. Using the method of designing elements of frames of the surfaces is actual for modeling of surfaces of technical items that function-interact with the environment. The developed method was proven while modelling functional surfaces that bound an impeller blade channel of a turbine compressor
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