Exact Algorithms for Mixed-Integer Multilevel Programming Problems

We examine multistage optimization problems, in which one or more decision makers solve a sequence of interdependent optimization problems. In each stage the corresponding decision maker determines values for a set of variables, which in turn parameterizes the subsequent problem by modifying its constraints and objective function. The optimization literature has covered multistage optimization problems in the form of bilevel programs, interdiction problems, robust optimization, and two-stage stochastic programming. One of the main differences among these research areas lies in the relationship between the decision makers. We analyze the case in which the decision makers are self-interested agents seeking to optimize their own objective function (bilevel programming), the case in which the decision makers are opponents working against each other, playing a zero-sum game (interdiction), and the case in which the decision makers are cooperative agents working towards a common goal (two-stage stochastic programming). Traditional exact approaches for solving multistage optimization problems often rely on strong duality either for the purpose of achieving single-level reformulations of the original multistage problems, or for the development of cutting-plane approaches similar to Benders\u27 decomposition. As a result, existing solution approaches usually assume that the last-stage problems are linear or convex, and fail to solve problems for which the last-stage is nonconvex (e.g., because of the presence of discrete variables). We contribute exact finite algorithms for bilevel mixed-integer programs, three-stage defender-attacker-defender problems, and two-stage stochastic programs. Moreover, we do not assume linearity or convexity for the last-stage problem and allow the existence of discrete variables. We demonstrate how our proposed algorithms significantly outperform existing state-of-the-art algorithms. Additionally, we solve for the first time a class of interdiction and fortification problems in which the third-stage problem is NP-hard, opening a venue for new research and applications in the field of (network) interdiction

A study of surface diffusion with the scanning tunneling microscope from fluctuations of the tunneling current

We introduce a new technique with high time resolution to measure surface diffusion by monitoring the time dependence of the STM tunneling current fluctuations. Diffusion parameters may be extracted from the decay of the tunneling current fluctuation autocorrelation function, c(t) = \langle[delta] i(0)[delta] i(t)\rangle , or from its Fourier transform, the power spectrum, W(f). Results were obtained for W(f) of oxygen adsorbed on stepped Si(111). Spectra for clean Si(111) show no temperature dependence while that for oxygen-covered Si(111) have signals which are two orders of magnitude greater and exhibit a strong temperature dependence: the spectra broadens with increasing temperature. The data fit the expected theoretical form well and by considering the low frequency regime, W(f) ~ -ln(f)/D, f → 0, the diffusion barrier for O/Si(111) was extracted, giving Ed = 0.92 ± 0.15 eV;The technique is tested if it can distinguish adsorbate diffusion from other surface processes which may interfere with the measurement. We have investigated how certain factors influence the shape of the correlation function or the power spectrum through a combination of experiments and Monte Carlo simulations. These factors include simultaneous diffusion on the substrate and on the tip, and the effect of inhomogeneous surface potentials caused by the electric field or impurities. Simultaneous diffusion on the substrate and on the tip produces a two-segment correlation function which is easily distinguished from that of a single diffusion process. Surface diffusion in inhomogeneous surface potentials (which can cause atoms to diffuse toward or away from the tip) result in correlation functions and power spectra that deviate from the theoretical forms as well. The technique is very highly local, can be used in a wide range of temperatures, and is able to measure a rather wide range of diffusion coefficients: ~10-15-10-8 cm2/sec

Formulación de un plan de gestión para el uso de agregados de concreto reciclado en concretos hidráulicos para una empresa constructora en la ciudad de Bogotá

Trabajo de investigaciónEn los últimos años las nuevas tecnologías y procesos permiten reducir el impacto de la construcción al integrar residuos como insumos; la investigación se centra en los agregados de concreto reciclado como insumo para la elaboración de concreto hidráulico, buscando elaborar la formulación de un plan de gestión útil para empresas constructoras de la ciudad de Bogotá. Se realizó una revisión documental y dos entrevistas a profesionales de obra, consolidando información en diez categorías: integración, alcance, tiempo, costo, calidad, recursos humanos, comunicaciones, riesgos, adquisiciones y grupos de interés, conforme los lineamentos del Project Management Instituto, para el uso de ACR en el marco de la gestión de obras de construcción. Se concluye que no es común el uso de ACR en concreto hidráulico, algunas obras pueden realizar la producción de concreto internamente pero aún no hacen uso de agregados reciclados puesto que la principal brecha se le atribuye al alto costo de los equipos. Normalmente se adquieren insumos que incluyan agregados reciclados, de manera que la responsabilidad sobre el proceso de reciclaje y reutilización del agregado queda a cargo del proveedor de materiales y no del constructor. De manera que el uso de ACR en concreto hidráulico requiere de mayor conocimiento y difusión, en especial entre constructoras de gran tamaño que por la frecuencia y variedad de proyectos que realiza puede amortizar los costos de maquinaria, e incluir dentro de su proceso de gestión de RCD un capítulo para el aprovechamiento interno de estos residuos.INTRODUCCIÓN 1. GENERALIDADES 2. MARCOS DE REFERENCIA 3. METODOLOGÍA 4. RESULTADOS 5. CONCLUSIONES REFERENCIASEspecializaciónEspecialista en Gerencia de Obras Civile

Surface mechanomyography and electromyography provide non-invasive indices of inspiratory muscle force and activation in healthy subjects

The current gold standard assessment of human inspiratory muscle function involves using invasive measures of transdiaphragmatic pressure (Pdi) or crural diaphragm electromyography (oesEMGdi). Mechanomyography is a non-invasive measure of muscle vibration associated with muscle contraction. Surface electromyogram and mechanomyogram, recorded transcutaneously using sensors placed over the lower intercostal spaces (sEMGlic and sMMGlic respectively), have been proposed to provide non-invasive indices of inspiratory muscle activation, but have not been directly compared to gold standard Pdi and oesEMGdi measures during voluntary respiratory manoeuvres. To validate the non-invasive techniques, the relationships between Pdi and sMMGlic, and between oesEMGdi and sEMGlic were measured simultaneously in 12 healthy subjects during an incremental inspiratory threshold loading protocol. Myographic signals were analysed using fixed sample entropy (fSampEn), which is less influenced by cardiac artefacts than conventional root mean square. Strong correlations were observed between: mean Pdi and mean fSampEn |sMMGlic| (left, 0.76; right, 0.81), the time-integrals of the Pdi and fSampEn |sMMGlic| (left, 0.78; right, 0.83), and mean fSampEn oesEMGdi and mean fSampEn sEMGlic (left, 0.84; right, 0.83). These findings suggest that sMMGlic and sEMGlic could provide useful non-invasive alternatives to Pdi and oesEMGdi for the assessment of inspiratory muscle function in health and disease.Peer ReviewedPostprint (published version

Technological breakthroughs impact within the cultural communicative process in regard to social media

Technological advances represent a fundamental change in the new millennium; besides, these advances has generated a great development in everything that daily works inside the world. One key change is based on the way people communicate by using technology tools; the increasingly common use puts the communication model in constant changing starting to separate each variable as a unit. At the same time intercultural, interaction and adaptation play an important role in the communication process by the use of technological advances; consequently these factors lead to increased effectiveness in measuring the success of communication.INTRODUCTION STATEMENT OF THE PROBLEM INTERCULTURAL COMPETENCE INTERCULTURALITY IN SOCIAL MEDIA CULTURE “STEREOTYPES ON/OFF LINE” INTERPERSONAL BEHAVIOR COMMUNICATION PROCESS AND SOCIAL MEDIA INTERACTION SOCIAL MEDIA AFFECTING COMMUNICATING PROCESS CONCLUSIONS REFERENCESPregradoProfesional en Lenguas ModernasLenguas Moderna

Stones of memory (II): The use in Roman times of prehistoric sacred spaces and monuments of Southern Iberia

En este artículo se aborda el análisis de la casuística conocida de reutilizaciones en época romana de lugares prehistóricos de carácter ritual en el Sur de la Península Ibérica. Los casos analizados se agrupan en tres categorías: (i) proximidad o solapamiento espacial de necrópolis prehistóricas y romanas, (ii)utilización funeraria y cultual de espacios interiores y exteriores de cámaras funerarias prehistóricas, (iii) reutilización de santuarios rupestres y estelas prehistóricas. Como conclusión se sugiere, primero, la necesidad de un replanteamiento de los criterios de registro y análisis empírico con que estos casos son abordados; segundo, la conveniencia de una reinterpretación completa de los mismos que parta de tener en cuenta los elementos de tradición y memoria que los sitios sagrados tienen dentro de las sociedades iberorromanas; y tercero, su valoración en clave de ideología religiosa e ideología política.This paper tackles the analysis of a series of cases of reutilisation in Roman times of prehistoric sacred spaces and monuments, recorded throughout the South of the Iberian Peninsula. The cases under study are grouped in three main categories: (i) spatial proximity or overlapping of prehistoric and Roman burial areas, (ii) reutilisation of the inner and outer spaces of prehistoric mortuary chambers, and (iii) re-use of rock art sanctuaries and prehistoric stelae. As a conclusion, we suggest, firstly, the need to reconsider the recording criteria by which the appearance of later materials in old monuments is archaeologically assessed; secondly, we point out the need to look at these cases from the viewpoint of the elements of tradition and memory that some old sacred sites convey for the Iberian-Roman populations. Finally, we suggest these cases must be interpreted in terms of religious and political ideology

Plan estratégico para la prevención de accidentes de transito de los estudiantes de los grados 1o y 11 que utilizan la bicicleta como medio de transporte de la institución educativa distrital Pablo de Tarso en la localidad de bosa.

Diseñar un plan estratégico para promover la prevención de accidentes de tránsito en los estudiantes de grados 10 y 11 que se transportan en bicicleta de la Institución Educativa Distrital Pablo de Tarso en la localidad de Bosa.Las condiciones de movilidad en la ciudad de Bogotá, cada vez más complejas e inseguras para la mayoría de los actores viales, representan en particular, un riesgo mayor para los usuarios de bicicleta quienes se movilizan sin la protección de una estructura que los resguarde en caso de accidentes por vías que carecen de señalización y enfrentando conductas arriesgadas por parte de otros actores viales. No obstante, hay otro factor clave que plantea riesgos para los usuarios de bicicleta y que tiene que ver con sus propios comportamientos y la falta de medidas que sirvan para proteger su vida y su integridad física mientras se movilizan. La suma de estos factores ha dejado un saldo para el año 2020 de 1200 ciclistas lesionados y 35 fallecidos en accidentes de tránsito de acuerdo con las cifras de la secretaria de movilidad. Teniendo en cuenta el creciente interés por parte de la ciudadanía en general por el uso de la bicicleta y en particular por parte de los niños, niñas y jóvenesMobility conditions in the city of Bogota, increasingly complex and unsafe for most road users, represent in particular, a greater risk for bicycle users who move without the protection of a structure to protect them in case of accidents on roads that lack signage and facing risky behaviors by other road users. However, there is another key factor that poses risks for bicycle users and that has to do with their own behaviors and the lack of measures to protect their lives and physical integrity while on the road. The sum of these factors has left a balance for the year 2020 of 1200 injured cyclists and 35 deaths in traffic accidents according to figures from the Secretary of Mobility. Taking into account the growing interest of citizens in general in the use of bicycles and in particular by children and young peopl

Prevalência de agentes causadores de mastite em rebanhos leiteiros na região de Castro, Paraná

Orientador: Prof. Dr. Rodrigo de AlmeidaCoorientador: Prof. Dr. Marcos Veiga dos SantosDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Agrárias, Programa de Pós-Graduação em Zootecnia. Defesa : Curitiba, 31/03/2023Inclui referências: p. 66-76Resumo: O presente estudo analisou amostras de leite com mastite clínica e subclínica em 50 rebanhos leiteiros localizados na região centro-oriental do Estado do Paraná, tendo como critérios de seleção volume de produção diário acima de 1.500 litros de leite e dificuldades com atendimento a níveis de CCS inferiores a 350.000 cél./ml. As análises foram realizadas em meios de cultura cromogênico que identificam e diferenciam patógenos gram-positivos e gram-negativos, ambos em CHROMagar. No período de setembro de 2020 a setembro de 2022 foram analisadas 12.714 amostras de leite de 7.166 vacas, sendo 4.653 amostras de mastite clínica e 8061 amostras de mastite subclínica. Nas mastites clínicas, 53,29% das amostras resultaram em casos positivos, 43,09% de resultados foram negativos (não houve crescimento bacteriano) e 3,63% de amostras contaminadas. Para as mastites subclínicas, obtivemos o resultado de 38,77% de casos positivos, 59,22% de resultados negativos e 2,01% de amostras contaminadas. O patógeno mais frequentemente envolvido na etiologia da mastite subclínica foi Staphylococcus não aureus (13,89%). Na mastite clínica, Streptococcus agalactiae/dysgalactiae apresentou a maior frequência (10,57%), e E. coli apresentou maior significância no grau de severidade. Também fizemos uma pesquisa avaliando a distribuição de agentes causadores de mastite clínica, bem como avaliando diferentes frequências de identificação dos patógenos de acordo com o tipo de instalação dos rebanhos (semiconfinamento [n=19], compost barn [n=4] e free-stall [n=18]), e classes ou categorias de contagem de células somáticas (CCS), número de vacas em lactação e produção diária de leite. O maior o volume de leite e o número de animais em lactação, possuem maior probabilidade de animais apresentarem mastite clínica com resultados positivos para patógenos ambientais. Os resultados encontrados nesse estudo evidenciam o impacto que a mastite causa nos rebanhos brasileiros, apresentando uma alta prevalência de resultados negativos (43,09% das culturas realizadas em eventos de mastite clínica e 59,22% em eventos de mastite subclínica), servindo de alerta e estímulo para o governo, indústria e produtores criarem e implementarem programas de controle da mastite para a melhoria da qualidade do leite.Abstract: The present study analyzed samples of milk with clinical and subclinical mastitis in 50 dairy herds located in the central-eastern region of the State of Parana, having as selection criteria a daily production volume above 1,500 liters of milk and difficulties meeting CCS levels of less than 350,000 cells per mL. Analyses were performed on chromogenic culture media that identify and differentiate gram-positive and gram-negative pathogens, both on CHROMagar. From September 2020 to September 2022, 12,714 milk samples from 7,166 cows were analyzed, including 4,653 samples of clinical mastitis and 8061 samples of subclinical mastitis. In clinical mastitis, 53.29% of the samples resulted in positive cases, 43.09% of results were negative (there was no bacterial growth), and 3.63% of the samples were contaminated. For subclinical mastitis, we obtained the results of 38.77% of positive cases, 59.22% of negative results, and 2.01% of contaminated samples. The pathogen most frequently involved in the etiology of subclinical mastitis was non-aureus Staphylococcus (13.89%). In clinical mastitis, Streptococcus agalactiae/dysgalactiae presented the highest frequency (10.57%), and E. coli presented the greatest significance in the degree of severity. We also carried out a survey evaluating the distribution of agents that cause clinical mastitis, as well as evaluating different frequencies of identification of pathogens according to the type of installation of the herds (semi-contained [n = 19], compost barn [n = 4], and free-stall [n = 18]), somatic cell count (SCC) classes or categories, number of cows in lactation, and daily milk production. The greater the volume of milk and the number of animals in lactation, the greater the probability of animals presenting clinical mastitis with positive results for environmental pathogens. The results found in this study show the impact that mastitis has on Brazilian herds, with a high prevalence of negative results (43.09% of cultures performed in clinical mastitis events and 59.22% in subclinical mastitis events), serving as a warning and encouragement for the government, industry, and producers to create and implement mastitis control programs to improve milk quality

Plan estratégico para la prevención de accidentes de transito de los estudiantes de los grados 1o y 11 que utilizan la bicicleta como medio de transporte de la institución educativa distrital Pablo de Tarso en la localidad de bosa.

Diseñar un plan estratégico para promover la prevención de accidentes de tránsito en los estudiantes de grados 10 y 11 que se transportan en bicicleta de la Institución Educativa Distrital Pablo de Tarso en la localidad de Bosa.Las condiciones de movilidad en la ciudad de Bogotá, cada vez más complejas e inseguras para la mayoría de los actores viales, representan en particular, un riesgo mayor para los usuarios de bicicleta quienes se movilizan sin la protección de una estructura que los resguarde en caso de accidentes por vías que carecen de señalización y enfrentando conductas arriesgadas por parte de otros actores viales. No obstante, hay otro factor clave que plantea riesgos para los usuarios de bicicleta y que tiene que ver con sus propios comportamientos y la falta de medidas que sirvan para proteger su vida y su integridad física mientras se movilizan. La suma de estos factores ha dejado un saldo para el año 2020 de 1200 ciclistas lesionados y 35 fallecidos en accidentes de tránsito de acuerdo con las cifras de la secretaria de movilidad. Teniendo en cuenta el creciente interés por parte de la ciudadanía en general por el uso de la bicicleta y en particular por parte de los niños, niñas y jóvenesMobility conditions in the city of Bogota, increasingly complex and unsafe for most road users, represent in particular, a greater risk for bicycle users who move without the protection of a structure to protect them in case of accidents on roads that lack signage and facing risky behaviors by other road users. However, there is another key factor that poses risks for bicycle users and that has to do with their own behaviors and the lack of measures to protect their lives and physical integrity while on the road. The sum of these factors has left a balance for the year 2020 of 1200 injured cyclists and 35 deaths in traffic accidents according to figures from the Secretary of Mobility. Taking into account the growing interest of citizens in general in the use of bicycles and in particular by children and young peopl

Fiscal Decentralization and Life Satisfaction in Chile

This research hinges upon the relationship between fiscal decentralization (FD) and subjective well-being (SWB) in Chile. We merge data from two household surveys (2011 and 2013) in which a life satisfaction question was included, with municipal-level information. By using a FD proxy that measures the share of municipal unconditional grants on all revenues, we produce an instrumental variable to test in the context of an ordered logistic multilevel model. Our contribution is twofold. First, we find evidence that, on average, FD does affect SWB positively. Second, we find this effect to depend on the satisfaction group in which individuals belong. Evidence from this study indicates that the effect in question is non-linear and that only high SWB groups are clearly benefitted. Since this reflects different priorities across SWB groups, this paper’s evidence is a call for a more aggressive inter-municipal fiscal equalization scheme