Active split-ring metamaterial slabs for magnetic resonance imaging

In this work, it is analyzed the ability of split-ring metamaterial slabs with zero/high permeability to reject/confine the radiofrequency magnetic field in magnetic resonance imaging systems. Using an homogenization procedure, split-ring slabs have been designed and fabricated to work in a 1.5T system. Active elements consisting of pairs of crossed diodes are inserted in the split-rings. With these elements, the permeability of the slabs can be automatically switched between a unity value when interacting with the strong excitation field of the transmitting body coil, and zero or high values when interacting with the weak field produced by protons in tissue. Experiments are shown for different configurations where these slabs can help to locally increase the signal-to-noise-ratio.Comment: 6 pages, 4 figure

SPATIAL DISTRIBUTION OF PARTNER-SEEKING MEN WHO HAVE SEX WITH MEN (MSM): AN EPIDEMIOLOGIC STUDY USING MSM GEOSOCIAL NETWORKING APPLICATIONS

Background: Geosocial networking (GSN) applications (apps) have made finding sexual partners easier for partner-seeking MSM, raising challenges for HIV/STI prevention but also providing opportunities for research. To date, little is known about app usage in smaller cities where there may be more stigma surrounding MSM. Objective: This study uses GSN apps to identify areas with high density partner-seeking MSM, and to characterize these areas using Census block group demographic measures in a Southern mid-sized city. Methods: Data collection points (n=62) were spaced in two-mile increments along nine routes (112 miles) covering the area. At each point, staff recorded the number of GSN app users within one mile using three GSN apps during two time periods. Data was entered into ArcGIS and empirical Bayesian kriging was used to create a raster estimating the number of app users throughout the county. Raster values were summarized for each of the county\u27s 208 census block groups and used as the outcome measure (i.e., GSN app usage). Using SAS v 9.4, Wilcoxon signed rank sum was used to examine temporal differences in app usage and negative log binomial regression examined census block group variables associated with GSN app usage. Results: In adjusted analyses of census block group data, median income (p \u3c 0.001) and percent Hispanic ethnicity (p \u3c 0.001-0.045) were found to be negatively associated with spatial density of GSN app-using MSM for all times and GSN apps in the final models. The presence of business zoning (p \u3c 0.001) and population density (p \u3c 0.001-0.045) were found to be positively associated with spatial density of GSN app-using MSM for all times and GSN apps in the final models. Conclusion: In this mid-sized city, GSN app usage was highest in areas with lower income but lowest in areas with larger Hispanic populations. This implies that Algarin 3 interventions using GSN apps could effectively be targeting lower income populations, but missing largely Hispanic communities

Code Switching: A Tool in the Classroom

There has been a tremendous growth of the Hispanic population in the United States leading to a large population of Spanish heritage speakers in our schools. Language diversity in the United States has been maintained primarily because of continuing immigration from non-English speaking countries (Gollnick & Chinn, 2009). Many school districts have adopted several types of programs to educate this growing population. One of the major issues being faced in the classroom concerns language development of learners using code switching. “Code switching, or the alternation of two languages within a single clause, sentence or turn is a complex, rule-governed use of language which offers a unique opportunity for studying some of the more complicated aspects of bilingual speech” (Dearholt & Valdes-Fallis 1978). While some teachers believe that students should only speak in the target language, others are indifferent or flexible with regard to the language students’ use in the classroom. Many of these teachers do not know to handle the situation or haven’t received adequate training to understand this process. This research project investigated the teachers’ knowledge about code switching and how they deal with it in the classroom with the purpose to identify the need of further information about Code Switching and how to use it to their advantage in the classroom. The method used to investigate this topic consisted of a questioned survey given to teachers of Grades K-8 from Eugenio María de Hostos Charter School. The survey consisted of the following questions: What is your definition of code switching? When do students code switch? Why do you think students code switch? What are your beliefs about code switching in the classroom? From 1 to 5 what are your feelings about students code-switching in the classroom? In what subject areas do you find students code switching? In what subject areas do you find yourself code switching? Do you perceive a higher success in students’ achievements when they code switch? What professional development would you like to see about code switching? The results of this research have two implications. The first implication from this thesis project would be how educators can enhance instruction to use code switching as language enhancement. The second implication would help educators identify the content areas where students need language instruction to build the vocabulary in the target language

Avanzando hacia una agricultura climáticamente inteligente: el papel del carbono orgánico en las funciones del suelo, los servicios ecosistémicos y la sostenibilidad de agroecosistemas

Current challenges, such as climate change and increasing pressure on primary food production, demand a transition toward more resilient and environmentally responsible agricultural models. In this context, preserving soil organic carbon (SOC) emerges as a key strategy to enhance soil functions, sustain essential ecosystem services, and strengthen agroecosystem resilience. This review article aims to analyze and synthesize the role of SOC in soil functions, its contribution to ecosystem service provision, its importance for achieving Sustainable Development Goals, and to identify the most promising management strategies for its increase and stabilization in soil. The research was based on an exhaustive bibliographic review with a descriptive approach, drawing from 43 review articles published between 2019 and 2024 in the Scopus database. The results demonstrate that SOC maintenance and enhancement are determinant factors for preserving soil functional integrity, supporting key ecosystem services, protecting food security, and mitigating climate change effects. Collectively, the findings highlight the need to promote management strategies oriented toward SOC regeneration as a central axis in building more resilient agroecosystems and advancing toward climate-smart agriculture.Los desafíos actuales, como el cambio climático y la creciente presión sobre la producción de alimentos primarios, exigen la transición hacia modelos agrícolas más resilientes y ambientalmente responsables. En este contexto, preservar el carbono orgánico del suelo (COS) se consolida como una estrategia clave para potenciar las funciones edáficas, sustentar servicios ecosistémicos esenciales y fortalecer la resiliencia de los agroecosistemas. Este artículo de revisión tiene como objetivo analizar y sintetizar el papel del COS en las funciones del suelo, su contribución a la provisión de servicios ecosistémicos, su importancia para el cumplimiento de los Objetivos de Desarrollo Sostenible, e identificar las estrategias de manejo más promisoras para su aumento y estabilización en el suelo. La investigación se fundamentó en una revisión bibliográfica exhaustiva con enfoque descriptivo, basada en 43 artículos de revisión publicados entre 2019 y 2024 en la base de datos Scopus. Los resultados evidencian que el mantenimiento y la valorización del COS son determinantes para preservar la integridad funcional del suelo, respaldar servicios ecosistémicos clave, proteger la seguridad alimentaria y mitigar los efectos del cambio climático. En conjunto, los hallazgos destacan la necesidad de promover estrategias de manejo orientadas a la regeneración del COS como eje central en la construcción de agroecosistemas más resilientes y en el avance hacia una agricultura climáticamente inteligente

Code Switching: A Tool in the Classroom

There has been a tremendous growth of the Hispanic population in the United States leading to a large population of Spanish heritage speakers in our schools. Language diversity in the United States has been maintained primarily because of continuing immigration from non-English speaking countries (Gollnick & Chinn, 2009). Many school districts have adopted several types of programs to educate this growing population. One of the major issues being faced in the classroom concerns language development of learners using code switching. “Code switching, or the alternation of two languages within a single clause, sentence or turn is a complex, rule-governed use of language which offers a unique opportunity for studying some of the more complicated aspects of bilingual speech” (Dearholt & Valdes-Fallis 1978). While some teachers believe that students should only speak in the target language, others are indifferent or flexible with regard to the language students’ use in the classroom. Many of these teachers do not know to handle the situation or haven’t received adequate training to understand this process. This research project investigated the teachers’ knowledge about code switching and how they deal with it in the classroom with the purpose to identify the need of further information about Code Switching and how to use it to their advantage in the classroom. The method used to investigate this topic consisted of a questioned survey given to teachers of Grades K-8 from Eugenio María de Hostos Charter School. The survey consisted of the following questions: What is your definition of code switching? When do students code switch? Why do you think students code switch? What are your beliefs about code switching in the classroom? From 1 to 5 what are your feelings about students code-switching in the classroom? In what subject areas do you find students code switching? In what subject areas do you find yourself code switching? Do you perceive a higher success in students’ achievements when they code switch? What professional development would you like to see about code switching? The results of this research have two implications. The first implication from this thesis project would be how educators can enhance instruction to use code switching as language enhancement. The second implication would help educators identify the content areas where students need language instruction to build the vocabulary in the target language.SUNY BrockportEducation and Human DevelopmentMaster of Science in Education (MSEd)Education and Human Development Master's These

Modeling and Evaluating Pilot Performance in NextGen: Review of and Recommendations Regarding Pilot Modeling Efforts, Architectures, and Validation Studies

NextGen operations are associated with a variety of changes to the national airspace system (NAS) including changes to the allocation of roles and responsibilities among operators and automation, the use of new technologies and automation, additional information presented on the flight deck, and the entire concept of operations (ConOps). In the transition to NextGen airspace, aviation and air operations designers need to consider the implications of design or system changes on human performance and the potential for error. To ensure continued safety of the NAS, it will be necessary for researchers to evaluate design concepts and potential NextGen scenarios well before implementation. One approach for such evaluations is through human performance modeling. Human performance models (HPMs) provide effective tools for predicting and evaluating operator performance in systems. HPMs offer significant advantages over empirical, human-in-the-loop testing in that (1) they allow detailed analyses of systems that have not yet been built, (2) they offer great flexibility for extensive data collection, (3) they do not require experimental participants, and thus can offer cost and time savings. HPMs differ in their ability to predict performance and safety with NextGen procedures, equipment and ConOps. Models also vary in terms of how they approach human performance (e.g., some focus on cognitive processing, others focus on discrete tasks performed by a human, while others consider perceptual processes), and in terms of their associated validation efforts. The objectives of this research effort were to support the Federal Aviation Administration (FAA) in identifying HPMs that are appropriate for predicting pilot performance in NextGen operations, to provide guidance on how to evaluate the quality of different models, and to identify gaps in pilot performance modeling research, that could guide future research opportunities. This research effort is intended to help the FAA evaluate pilot modeling efforts and select the appropriate tools for future modeling efforts to predict pilot performance in NextGen operations

EJM Chain Fall Tooling Optimization

The following report describes the progress made by the EJM Chain Fall Tooling Optimization Team since the In-Progress Review. The team has finalized the facility layout design for the chain fall area including the concept of operations, functional requirements, and performance specifications. The scope of the project is completing the new procedures for reducing waste and completing the AutoCAD drawing of the final design. The team researched the objectives accomplished by the new layout design. The goal of the project is to reduce the safety hazards and increase productivity. The team shifted the focus to the salvage, recycling, and waste policy for the chain fall area and the assessment time of the kits﹣kit turns, time needed to assess, amount of inventory. The team estimated the average cost of the missing kits in the chain fall area based on average tool costs. The team estimated the losses of the company for two years (2016 and 2017). Although the team has not currently finished all the cost benefit analysis for each alternative, the team has finalized the outcome of the problem-solving approach for most of the problems found in the chain fall area. The reason for this is that the team is still waiting to receive data from Siemens. After finalizing the design area, the team makes recommendations for future studies based on the limited time to finalize all the proposals made in the report

Influence of intramolecular ligand interactions on the chemistry of ruthenium polypyridyl complexes

The Kelson group has had a successful history in developing catalysts for ketone transfer hydrogenation chemistry and possible hydrocarbon oxidation chemistry. These catalysts, based on the formulation (Trpy)Ru(L)2(0H2) where Trpy =2,2':6',2"terpyridine and L=2-pyridonate (PyO) or 2-pyrrolidinonate (PyrrolO), have been studied extensively. However, the subtle electronic details that support the chemistry of these complexes remain elusive, but important to optimizing their activity. The objective of this thesis work was to probe these electronic features through ligand substituent effects. Modification of the (Trpy)Ru(L)2(0H2) complexes provide a rare opportunity to investigate two modes of chemistry using a single class of complexes. Three series of complexes were prepared: (XTrpy)Ru(PyrrolO) with 4' -chloro- 2,2':6' ,2"-terpyridine, 4'( 4'" -chlorophenyl)-2,2' :6'2"-terpyridine, 4'( 4"'-methylphenyl)- 2,2' :6'2"-terpyridine, 4'(4'"-trifluorophenyl)-2,2':6'2"-terpyridine, and 4', 4', 4"-tri-tertbutyl)- 2,2':6'2"-terpyridine, (Trpy)Ru(XPy0)2(0H2) and [(Bpy)2Ru(XPyO)(OH2)]Cl (where Bpy=2,2'-bipyridine) with 5-chloro-2-pyridonate, 5-trifluoromethyl-2-pyridonate, 3-methoxy-2-pyridonate for XPyO. Most of these ligands were commercially available, but synthetic methods had to be developed to prepare 4' -( 4"' -substituted phenyl)- 2,2' :6 '2"-terpyridines. All new ligands and complexes were characterized by 1H NMR, FT-IR, and UV-Visible spectroscopy. The complex (Trpy)Ru(3-methoxy-2- pyridonato)2(0H2) were further characterized by x-ray crystallography. The electrochemistry of the (Trpy)Ru(XPy0)2(0H2) and [(Bpy)2Ru(XPy0)2(0H2)]Cl complexes were surveyed by rotating disk voltammetry in aqueous pH 10 to 13 buffers. This study was intended to determine the input of hydrogen bonding from the XPyO ligands on the electrochemistry of the Run(OH2) moiety. Each complex exhibited a one electron-one proton Run(OH2)/Rum(OH) oxidation couple (as evidenced by a -60 m V /pH slope in the potential versus pH dependence) but no Rum(OH)/Ru1v (0) oxidations familiar for (Trpy)Ru(Bpy)(OH2)2+ and (Bpy)2Ru(pyridine)(OH2)2+. Hydrogen bonding between the XPyO ligands and the Run(OH2) aquo group assists oxidation to the Rum(OH) state versus pyridine itself, but strongly discourages further oxidation to RuN(O). Electron donating substituents only modestly stabilized the higher oxidation state. Loss of hydrogen bonding between XPyO ligands and the Rum(OH) hydroxyl group destabilizes the oxidized complex. Electron donating substituents modestly exaggerated this effect suggesting it was due to an electrostatic rather than a covalent interaction. Attempts to prepare and isolate higher oxidations states of (Trpy)Ru(XPy0)2(0H2) complexes were unsuccessful likely due to the relative instability of the Rum( OH) states. The activity of the (XTrpy)Ru(Pyrrol0)2(0H2) and (Trpy)Ru(XPy0)2(0H2) for the transfer hydrogenation of 2-adamantanone by 2-propanol was surveyed by fitting yield versus time profiles to an integrated rate law for the catalytic cycle. The rate determining hydrogen transfer from the catalyst to ketone (k2) was found to be accelerated by electron withdrawing groups on PyO and electron donating groups on XTrpy. Catalyst pKb's measured photomerically in aqueous buffers exhibited little to no dependence on substituents on XPyO and XTrpy. These results suggest that ligand substituent effects encourage transfer hydrogenation by the relative stabilization of the ruthenium dyz orbital over the dxz (likely clearing an electrostatic path or hydride migration) rather than through ligand basicity. These studies have made important contributions to the understanding of (Trpy)Ru(L)2(0H2) complexes. Since, hydrogen-bond acceptor ligands discourage the Ru1v (0) oxidation state, future efforts will focus on complexes bearing hydrogen-bond donor ligands. Further, new transfer hydrogenation catalysts will be designed to shift electron density from the ruthenium dyz orbital toward the dxz to facilitate hydride migration. This work represents an important step toward practical hydrocarbon oxidation and ketone transfer hydrogenation catalysts.Includes bibliographical references (leaves 121-124)California State University, Northridge. Department of Chemistry

An institutional and relational approach to social accountability: lessons from two Colombian cities

Social accountability is considered a key democratic feature that can help to secure responsiveness, service delivery and control power-holders. The thesis responds to how may social accountability be secured in weak democratic contexts through three sub-questions: First, to what extent do public officials align with the role of 'account-givers' and societal actors that of 'account-holders'? Second, how may societal actors assess the performance of public officials? And third, how may societal actors impose consequences on public officials, and public officials respond? The thesis draws on recent studies analysing social accountability beyond mechanisms and is interested in how context matters for the success of such initiatives and how political history and other structures shape the interactions between state and society. This research contributes to this body of literature by employing a relational and institutional approach, analysing social accountability as an institution. The thesis explores the set of rules, practices and narratives interacting with officials and societal actors and creating regular patterns of (un)accountable behaviour such as monitoring, access to information, justifications, deliberation and possibly imposing sanctions, rewards and call or provision of redress. The research is based on a case study focusing on two Colombian cities where social accountability is expected to emerge given traditional accountability deficits, corruption, and insufficient provision of services. The findings are drawn from 40 semi-structured interviews, documentary analysis and observation of public hearings. The study suggests that a dyadic relational approach may overlook civil society organisations as intermediaries between public officials and citizens and the significance of such a role in social accountability institutionalisation. The thesis also uncovers the tensions between institutional stability and weakening and argues they can be explained by the interaction with other institutions, such as exclusionary bipartisanism, clientelism and decentralisation. While exclusionary bipartisanism and clientelism create incentives for ‘window dressing’, decentralisation within cities can complement social accountability arrangements. These institutional dynamics underpin gaps between institutional arrangements hindering social accountability and further reinforcing power asymmetries between public officials or political elite and citizens, especially those facing critical socioeconomic challenges. While rules prescribe ongoing interactions, in practice, social accountability is reduced to specific events where local governments exercise power and control and portray narratives of compliance and responsiveness. Simultaneously, societal actors’ ability to participate and impose consequences is limited but some resist and push forward changes, contributing to understanding the importance of analysing multiple actors’ behaviours and how they shape institutions

Desarrollo economico de Ciudad del Este Alto-Parana, Paraguay

Trabajo de conclusión del Curso presentado al Instituto Latino Americano de Economía, Política y Sociedades de la Universidad Federal de la Integración Latino Americana, como requisito para la aprobación del Curso de Ciencias Económicas - Economía, Integración y Desarrollo. Orientador: Dr. Gilson Batista de Oliveira.Este estudio tiene como propósito comprender el desarrollo económico y la dinámica del comercio de Ciudad del Este, un municipio que se encuentra en el Departamento de Alto Paraná (Paraguay). Los procedimientos metodológicos serán guiados por la revisión bibliográfica y de literatura, también el método de lectura exploratoria con el fin de comprender la situación del comercio y comprender la importancia de esta pequeña ciudad que se encuentra en la triple frontera: Paraguay (Ciudad del Este), Brasil (Foz de Iguazú) y Argentina (Puerto Iguazú). El objetivo es verificar las nuevas formas de desarrollo local-regional, y también identificar los principales potenciales económica que cuenta el municipio en los últimos tiempos.O estudo visa compreender a dinâmica do desenvolvimento econômico do comércio de Ciudad Del Este. O município é localizado no Departamento de Alto Paraná (Paraguai). Os procedimentos metodológicos aplicados são revisão da literatura, e o método de leitura exploratória, a fim de compreender a situação do comércio e a importância desta pequena cidade localizada na tríplice fronteira Paraguai (Ciudad del leste), Brasil (Foz do Iguaçu) e Argentina (Puerto Iguazu). O objetivo é verificar as novas formas de desenvolvimento local-regional e também identificar o potencial econômico que tem o município nos últimos tempo