POLISphone: Creating and Performing With a Flexible Soundmap

(Abstract to follow

GEMINI near-infrared spectroscopic observations of young massive stars embedded in molecular clouds

K-band spectra of young stellar candidates in four southern hemisphere clusters have been obtained with the near-infrared spectrograph GNIRS in Gemini South. The clusters are associated with IRAS sources that have colours characteristic of ultracompact HII regions. Spectral types were obtained by comparison of the observed spectra with those of a NIR library; the results include the spectral classification of nine massive stars and seven objects confirmed as background late-type stars. Two of the studied sources have K-band spectra compatible with those characteristic of very hot stars, as inferred from the presence of Civ, Niii, and Nv emission lines at 2.078 micron, 2.116 micron, and 2.100 micron respectively. One of them, I16177 IRS1, has a K-band spectrum similar to that of Cyg OB2 7, an O3If* supergiant star. The nebular K-band spectrum of the associated UC Hii region shows the s-process [Kriii] and [Seiv] high excitation emission lines, previously identified only in planetary nebula. One young stellar object (YSO) was found in each cluster, associated with either the main IRAS source or a nearby resolved MSX component, confirming the results obtained from previous NIR photometric surveys. The distances to the stars were derived from their spectral types and previously determined JHK magnitudes; they agree well with the values obtained from the kinematic method, except in the case of IRAS15408-5356, for which the spectroscopic distance is about a factor two smaller than the kinematic value.Comment: This is the version that will be published by the Montly Notices of the Royal Astronomical Societ

Programación lineal para el análisis y la recreación virtual de episodios históricos: la distribución de la artillería durante el sitio de Bilbao en 1874

[EN] The current digital technologies development makes it possible to apply new forms of studying historical events considering the geographical point of view. They rely on the location and the relationships among the different elements that took part in them over a recreated space (e.g. relief, roads, rivers); once these elements have been laid out on the virtual space, Geographic Information Systems (GIS) can be used to analyse several factors, such as distances, visibility, connectivity and so on. Nevertheless, the development of the actions was also driven by the aims, needs and beliefs (either wise or misguided) of the people/actors involved in those situations; therefore, some ways of including reasoning would significantly improve the actual recreation and understanding of the episodes. In this sense, “linear programming” is a very versatile tool for system modelling and optimization that is broadly used in many fields (e.g. industry, transports, agriculture, etc.). Likewise, this technique can also be applied to past scenarios to simulate dynamics and cross-check sources. In this text, two models regarding the distribution and the allocation of supplies during the siege of Bilbao, in the framework of the Third Carlist War (1872-1876), from both parties —beleaguerer and besieged— were established based on the war front textual reports. In these models, the scenario is recreated through the system variables (which define the alternatives that can be or could have been taken) and the constraints (which limit the range of action); moreover, the actors’ goals that guided the course of events are defined by the objective. Despite the simplification in the modelling, the results show very interesting hints about the dynamics involved during the processes and are able to highlight some critical issues that significantly conditioned the final results. Besides, the modelling process itself proved to be an opportunity for collaboration between historians and computer scientists.[ES] El desarrollo de las tecnologías digitales ha posibilitado nuevas formas de estudio de los sucesos históricos desde la perspectiva geográfica. Estos métodos se basan en la localización (sobre un espacio que incluye el relieve, las vías de comunicación, los ríos, etc.) y el establecimiento de las relaciones entre los diferentes elementos que intervinieron en dichos sucesos. Una vez que toda esta información ha sido representada en el espacio virtual, es posible recurrir a los Sistemas de Información Geográfica (SIG) con el fin de analizar diversos factores como las distancias, la visibilidad, la conectividad, etc. Sin embargo, resulta evidente que el desarrollo de los acontecimientos también estuvo condicionado por las intenciones, las necesidades y las impresiones (tanto correctas como equivocadas) de las personas que intervinieron en ellos; por lo tanto, resulta oportuno pensar que la recreación del desarrollo de los eventos históricos, así como su correcta comprensión, mejorará sustancialmente si se incorpora algún método para simular el razonamiento de los actores. En esta línea, la “programación lineal” es una opción versátil para el modelado y la optimización de sistemas que cuenta con una amplia experiencia en diversos campos como la industria, los transportes, la agricultura, etc. Asimismo, esta técnica de modelado también es aplicable a escenarios históricos con el fin de realizar simulaciones de las dinámicas que se establecieron y como método de validación de las fuentes. En el presente texto, se desarrollan —con base a los informes del frente de guerra— dos modelos relativos a la distribución de suministros durante el sitio de la villa de Bilbao —que tuvo lugar en el contexto de la Tercera Guerra Carlista (1872-1876)— que corresponden a ambas partes (es decir, a los sitiadores y a los sitiados). En los modelos, el escenario se recrea a través de las variables del sistema (las cuales definen las alternativas que pueden tomarse) y las restricciones (que limitan el rango de acción), por otro lado, las metas que guiaron el curso de los acontecimientos se definen mediante el objetivo. A pesar de la simplificación que implica el proceso de modelado, los resultados ofrecen interesantes indicaciones sobre las dinámicas que intervinieron en el desarrollo de los procesos y son capaces de identificar aspectos críticos que, efectivamente, condicionaron los resultados finales. Asimismo, el propio proceso de modelado resulta ser una oportunidad de colaboración entre historiadores y expertos informáticos. The participation of Gorka Martín and Jaione Korro in this research is supported by the Basque Government through grants for doctoral studies of the call 2019-2020. Figures 1 and 3 are reproduced here with the permission of the Bizkaia Provincial Council Historical Archive (Archivo Histórico de la Diputación Foral de Bizkaia / Bizkaiko Foru Aldundiaren Agiritegi Historikoa).Rodriguez-Miranda, A.; Ferreira-Lopes, P.; Martín-Etxebarria, G.; Korro Bañuelos, J. (2021). Linear programming for the analysis and virtual recreation of historical events: the allocation of the artillery during the Siege of Bilbao in 1874. Virtual Archaeology Review. 12(25):99-113. https://doi.org/10.4995/var.2021.15278991131225Alves, D., & Queiroz, A. I. (2015). Exploring literary landscapes: from texts to spatiotemporal analysis through collaborative work and GIS. International Journal of Humanities and Arts Computing, 9(1), 57-73. http://www.euppublishing.com/doi/abs/10.3366/ijhac.2015.0138Bachagha, N., Wang, X., Luo, L., Li, L., Khatteli, H., & Lasaponara, R. (2020). Remote sensing and GIS techniques for reconstructing the military fort system on the Roman boundary (Tunisian section) and identifying archaeological sites. Remote Sensing of Environment, 236, 111418. https://doi.org/10.1016/j.rse.2019.111418Barone, P. M. (2019). Bombed Archeology: Towards a Precise Identification and a Safe Management of WWII's Dangerous Unexploded Bombs. Heritage, 2(4), 2704-2711. https://doi.org/10.3390/heritage2040167Bevan A., & Wilson, A. (2013). Models of settlement hierarchy based on partial evidence. Journal of Archaeological Science, 40, 2415-2427. https://doi.org/10.1016/j.jas.2012.12.025Blanco-Rotea, R. (2015). Arquitectura y Paisaje. Fortificaciones de frontera en el sur de Galicia y norte de Portugal. (Doctoral thesis, Universidad del País Vasco/Euskal Herriko Unibertsitatea, Spain). http://hdl.handle.net/10261/122137Bocinsky, R. K. (2014). Extrinsic site defensibility and landscape-based archaeological inference: An example from the Northwest Coast. Journal of Anthropological Archaeology, 35, 164-176. http://dx.doi.org/10.1016/j.jaa.2014.05.003Brughmans, T. (2013). Thinking Through Networks: A Review of Formal Network Methods in Archaeology. Journal of Archaeological Method and Theory, 20, 623-662. https://doi.org/10.1007/s10816-012-9133-8Caldwell, T. (2019). Defend Your Coast: Network Analysis of Crusader Fortifications and Settlements in the Kyrenia Region of Cyprus (Doctoral thesis, Faculty of the Program in Maritime Studies of Department of History East Carolina University, United States of America). http://hdl.handle.net/10342/7261Canosa-Betés, J. (2016). Border surveillance: Testing the territorial control of the Andalusian defense network in center-south Iberia through GIS. Journal of Archaeological Science: Reports, 9, 416-426. http://dx.doi.org/10.1016/j.jasrep.2016.08.026Cooper, D., & Gregory, I. N. (2011). Mapping the English Lake District: a literary GIS. Transactions of the Institute of British Geographers, 36(1), 89-108. https://doi.org/10.1111/j.1475-5661.2010.00405.xCrespo Solana, A. (ed.). (2014). Spatio-temporal Narratives: Historical GIS and the Study of Global Trading Networks (1500-1800). Newcastle: Cambridge Scholars Pub.Cuca, B., Brumana, R., Scaioni, M., & Oreni, D. (2011). Spatial data management of temporal map series for cultural and environmental heritage. International Journal of Spatial Data Infrastructures Research, 6, 97-125. http://dx.doi.org/10.2902/1725-0463.2011.06.art5Cuerpo del Estado Mayor del Ejército (ed.) (1885). Narración militar de la Guerra Carlista de 1869 a 1876, Madrid: Imprenta y Litografía del Depósito de la Guerra, Tomo IV.de Kleijn, M., de Hond, R. J. F., & Martinez-Rubi, O. (2016). A 3D GIS Infrastructure for "Mapping the Via Appia". Digital Applications in Archaeology and Cultural Heritage, 3(2), 23-32. https://doi.org/10.1016/j.daach.2016.03.001Deidda, M., Musa, C., & Vacca, G. (2015). A GIS of Sardinia's coastal defense system (XVI - XVIII century). The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, XL-4/W7, 17-22. https://doi.org/10.5194/isprsarchives-XL-4-W7-17-2015Düring, M. (2016). How reliable are centrality measures for data collected from fragmentary and heterogeneous historical sources? A case study. In T. Brughmans, A. Collar, & F. Coward (eds.), The Connected Past: Challenges to Network Studies in Archaeology and History, Oxford: Oxford University Press, 85-101. http://hdl.handle.net/10993/31309Earley-Spadoni, T. (2015). Landscapes of warfare: Intervisibility analysis of Early Iron and Urartian fire beacon stations (Armenia). Journal of Archaeological Science: Reports, 3, 22-30. http://dx.doi.org/10.1016/j.jasrep.2015.05.008Ferreira-Lopes, P. (2015). La producción del sistema ferroviario. Hacia una IDE histórica del patrimonio ferroviario de Andalucía. Virtual Archaeology Review Journal, 13, 41-50. https://doi.org/10.4995/var.2015.4371Ferreira-Lopes, P., & Molina Rozalen, J. F. (2018). Historical SDI, thematic maps and analysis of a complex network of medieval towers (13th-15th century) in the Moorish Strip. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLII-4, 177-183. https://doi.org/10.5194/isprs-archives-XLII-4-177-2018Ferreira-Lopes, P., & Pinto Puerto, F. (2018). GIS and graph models for social, temporal and spatial digital analysis in heritage: The case-study of Ancient Kingdom of Seville Late Gothic production. Digital Application in Archaeology and Cultural Heritage, 9, 1-14. https://doi.org/10.1016/j.daach.2018.e00074Garrec, T. (2019). Continuous patrolling and hiding games. European Journal of Operational Research, 277, 42-51. https://doi.org/10.1016/j.ejor.2019.02.026Jahjah, M., Ulivieri, C., Invernizzi, A., & Parapetti, R. (2007). Archaeological remote sensing application pre-post war situation of Babylon archaeological site-Iraq. Acta Astronautica, 61(1-6), 121-130. https://doi.org/10.1016/j.actaastro.2007.01.034Liceras-Garrido, R., Favila-Vázquez, M., Bellamy, K., Murrieta-Flores, P., Jiménez Badillo, D., & Martins, B. (2019). Digital Approaches to Historical Archaeology: Exploring the Geographies of 16th Century New Spain. Journal of Archaeology and Anthropology, 2(1). https://doi.org/10.33552/OAJAA.2019.02.000526Llobera, M. (2007). Reconstruction visual landscapes. World Archaeology, 39(1), 51-69. https://doi.org/10.1080/00438240601136496Lock, G., & Pouncett, J. (2017). Spatial thinking in archaeology: Is GIS the answer? Journal of Archaeological Science, 84, 129-135. http://dx.doi.org/10.1016/j.jas.2017.06.002Luo, L., Wang, X., & Cai, H. (2014). An Integrated 3S and Historical Materials Analysis of the Keriya Paleoriver, NW China. IOP Conference Series: Earth and Environmental Science, 17(1), 012165. https://doi.org/10.1088/1755-1315/17/1/012165Martín, G. (2017). Aproximación al estudio de tres fuertes de las guerras carlistas en el entorno de Bilbao. Arkeogazte, 7, 193-220.Martín, G. (2019). Defendiendo la "Invicta Villa". La línea de Bilbao y su ría y Abra durante la Última Guerra Carlista (1872-1876). Vasconia, 43, 33-73.Martindale, A, & Supernant, K. (2009). Quantifying the defensiveness of defended sites on the Northwest Coast of North America. Journal of Anthropological Archaeology, 28,191-204. http://dx.doi.org/10.1016/j.jaa.2009.01.001Mullins, P. (2016). Webs of defense: Structure and meaning of defensive visibility networks in Prehispanic Peru. Journal of Archaeological Science: Reports, 8, 346-355. https://doi.org/10.1016/j.jasrep.2016.05.022Murphy, K. M., Gittings, B., & Crow, J. (2018). Visibility analysis of the Roman communication network in southern Scotland. Journal of Archaeological Science: Reports, 17, 111-124. https://doi.org/10.1016/j.jasrep.2017.10.047Murrieta-Flores, P. (2012). Understanding human movement through spatial technologies. The role of natural areas of transit in the Late Prehistory of South-western Iberia. Trabajos de Prehistoria, 69(1), 103-122. https://doi.org/10.3989/tp.2012.12082Peeples, M. A. (2019). Finding a Place for Network in Archaeology. Journal of Archaeological Research, 27, 451-499. https://doi.org/10.1007/s10814-019-09127-8Prieto, A. J., Ortiz, R., Macías-Bernal, J. M., Chávez, M. J., & Ortiz, P. (2020). Artificial intelligence applied to the preventive conservation of heritage buildings. In P. Ortiz, F. Pinto, P. Verhagen, & A. J. Prieto (Eds.), Science and Digital Technology for Cultural Heritage - Interdisciplinary Approach to Diagnosis, Vulnerability, Risk Assessment and Graphic Information Models. Proceedings of the 4th International Congress Science and Technology for the Conservation of Cultural Heritage (TechnoHeritage 2019), March 26-30, 2019, Sevilla, Spain (pp. 245-249). London: CRC Press. https://doi.org/10.1201/9780429345470-45Quesada-García, S., & Romero-Vergara, G. (2019). El sistema de torres musulmanas en tapial de la Sierra de Segura (Jaén). Una contribución al estudio del mundo rural y el paisaje de al-Andalus. Arqueología de la Arquitectura, 16, e079. https://doi.org/10.3989/arq.arqt.2019.001Richards-Risseto, H. (2017). What can GIS + 3D mean for landscape archaeology? Journal of Archaeological Science, 84, 10-21. http://dx.doi.org/10.1016/j.jas.2017.05.005Rinaudo, F., & Devoti, C. (2013). GIS and land history: the documentation of the ancient Aosta dukedom. ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences, II-5/W1, 265-270. https://doi.org/10.5194/isprsannals-II-5-W1-265-2013Roldán, I., & Escribano, S. (2015). Arqueología del Conflicto Carlista. Valoración del legado material de varios fuertes del Frente de Estella. Arkeogazte, 5, 133-149.Roldán, I., & Escribano, S. (2017). Programa de investigación del patrimonio de las guerras carlistas en Navarra. Primeras intervenciones. Trabajos de arqueología navarra, 29, 281-289.Roldán, I., Martín, G., & Escribano, S. (2019). The archaeology of civil conflict in nineteenth century Spain: material, social and mnemonic consequences of the Carlist Wars. World Archaeology, 51(5), 709-723. https://doi.org/10.1080/00438243.2020.1741441Rua, H., Gonçalves, A.B., & Figueiredo, F. (2013). Assessment of the Lines of Torres Vedras defensive system with visibility analysis. Journal of Archaeological Science, 40, 2113-2123. http://dx.doi.org/10.1016/j.jas.2012.12.012Rupp, C. J., Rayson,P., Gregory,I., Hardie, A., Joulain, A., & Hartmann, D. (2014). Dealing with heterogeneous big data when geoparsing historical corpora. IEEE International Conference on Big Data (Big Data) (pp. 80-83). Washington DC, United States of America. https://doi.org/10.1109/BigData.2014.7004457Scott, D., & McFeater, A. (2011). The archaeology of historic battlefields: a history and theoretical development. Conflict Archaeology. Journal of Archaeological Research, 19, 103-132. https://doi.org/10.1007/s10814-010-9044-8Suárez, J. L., & Sancho-Caparrini, F. (2016). Nuevas Tecnologías y Patrimonio: más allá de la digitalización. El caso del "Hispanic Baroque Project". Retrieved August 31, 2020, from http://www.cs.us.es/~fsancho/?e=27Trapero Fernández, P. (2016). Roman viticulture analysis based on Latin agronomists and the application of a geographic information system in Lower Guadalquivir. Virtual Archaeology Review, 7(14), 53-60. http://dx.doi.org/var.2016.4481Verhagen, P., Nuninger, L., & Groenhuijzen, M. (2019). Modelling of pathways and movement networks in archaeology: an overview of current approaches. In P. Verhagen et al. (Eds.), Finding the Limits of the Limes, Computational Social Sciences. Computational Social Sciences (pp. 217-249). Cham: Springer. https://doi.org/10.1007/978-3-030-04576-0_11Verhagen, P., Nuninger, L., Tourneux, F. P., Bertoncello, F., & Jeneson, K. (2013). Introducing the human factor in predictive modelling: a work in progress. In CAA 2012. Archaeology in the digital era. Papers from the 40th annual conference of computer applications and quantitative methods in archaeology, Southampton, 26-29 March 2012 (pp. 379-388). Amsterdam: Amsterdam University Press. https://doi.org/10.1515/9789048519590-041Villalba, D., & Bueno, Y. (2012). Decisiones empresariales con hoja de cálculo. Madrid, Spain: Pirámide.Whitley, T. G. (2017). Geospatial analysis as experimental archaeology. Journal of Archaeological Science, 84, 113-114. http://dx.doi.org/10.1016/j.jas.2017.05.00

Iris image quality assessment based on ISO/IEC 29794-6:2015 standard / Avaliação da qualidade da imagem da íris com base na norma ISO / IEC 29794-6: 2015

O processo de reconhecimento biométrico da íris é uma das tecnologias biométricas mais consistentes entre outras disponíveis atualmente. No entanto, sua eficiência e precisão podem ser afetadas por imagens de íris de baixa qualidade usadas como entrada para um sistema de reconhecimento, assim, o desempenho global é reduzido. Nesse contexto, este trabalho propõe um estudo de avaliação para determinar o impacto da qualidade da imagem da íris no desempenho do sistema biométrico da íris, utilizando as principais métricas apresentadas na norma ISO / IEC 29794-6: 2015. Os testes experimentais são realizados usando um banco de dados de imagens de íris e o software de reconhecimento biométrico OSIRIS, ambos amplamente aceitos e referenciados nas últimas pesquisas. Os resultados experimentais mostram os valores de intervalo de cada métrica de qualidade e o número de imagens que atingem os valores mínimos necessários. O desempenho do sistema biométrico é avaliado pelos parâmetros True-Match (TM) e False Non-Match (FNM); assim, foi possível identificar que quanto maior o nível de qualidade da imagem, menor o valor de FNM; portanto, o desempenho do sistema é aprimorado. 

Increase of cooperation permitted by computers in a distance education environment

This article analyzes part of the results of a social research program developed along with neighborhood health agents of São Marcos and Santa Mônica in Campinas, state of São Paulo. It was a longitudinal study carried out over a period of a year and a half carried out throughout three phases: face-to-face, intermediary stage and pure distance work. In this article we solely discuss the activities during the face-to-face phase, whereby agents learnt how to use the computer and the TelEduc system. We opted to apply qualitative observation given that the main objective of this research was to identify Piaget's developmental stages within the context of the agents' capacity to understand tangible and intangible aspects of the technological universe. This relationship was possible when the subjects began to interact with basic elements of the computer and with TelEduc. After overcoming a state of anomia and understanding the tools that allowed a heteronomous attitude, agents used resources allowing them to enter a relationship of cooperation.O artigo contempla parte dos resultados de uma pesquisa-ação desenvolvida junto aos agentes de saúde dos bairros São Marcos e Santa Mônica, em Campinas-SP. Trata-se de pesquisa longitudinal, com duração de um ano e meio, envolvendo três fases: presencial, semipresencial e a distância. Aqui tratamos apenas das atividades ocorridas na fase presencial, nas quais os agentes começaram a aprender a utilizar o computador, e do TelEduc. Para tanto, optamos por uma observação qualitativa, já que o objetivo principal foi aferir os estágios de desenvolvimento de Piaget com a capacidade dos agentes em dominar as entidades tangíveis e intangíveis da informática (compreendem-se as entidades tangíveis como os elementos de hardware; e as entidades intangíveis, como os de software). Essa relação foi possível quando eles, de maneira presencial, começaram a interagir com os elementos básicos do computador e com o TelEduc. Após superarem a anomia e terem dominado as ferramentas que favoreceram posturas heterônomas, os agentes manipularam recursos que permitiram o começo de uma relação de cooperação.Este artículo contempla parte de los resultados de una investigación-acción desarrollada juntamente con los agentes de salud de los barrios Sao Marcos y Santa Mônica, Campinas/ Sao Paulo. Fue una investigación longitudinal, con duración de un año y medio, que constó de tres fases: Presencial, semipresencial y a distancia. En este artículo tratamos solamente de las actividades ocurridas en la fase presencial, en la cual los agentes comenzaron a aprender a utilizar el ordenador y TelEduc. Optamos por una observación cualitativa, ya que el objetivo principal fue asociar las tres fases de desarrollo piagetianas -anomia, heteronomia y cooperación - con la capacidad de los agentes de dominar las propiedades tangibles e intangibles de la informática. Esta asociación fue posible cuando ellos empezaron a interactuar con los elementos básicos del ordenador y del TelEduc. Después de superar la anomia y de dominar las herramientas qué favorecieran actitudes heterónomas, los agentes manipularon recursos que permitieron el comienzo de una relación de cooperación.42744

Leukemic transformation of the hematopoietic stem cell microenvironment

O microambiente das células-tronco hematopoiéticas é responsável por coordenar diversos eventos envolvidos na produção de células sanguíneas. Essa renovação hematopoiética só é possível graças às interações e sinalizações bem ordenadas que mantém a harmonia do tecido. Nas leucemias ocorre ruptura nesses mecanismos de controle e ocorre processo de transformação leucêmica do microambiente, de forma a favorecer a manutenção neoplásica do tecido sanguíneo. O objetivo deste estudo foi expor o processo de transformação leucêmica do microambiente, no âmbito das modificações celulares e moleculares sofridas para sustentar o tumor. Trata-se de um artigo de revisão narrativa e as bases de dados Pubmed, Scielo, Cocrahne Library e MedLine foram consultadas em busca de publicações dos últimos anos sobre o tema. Os dados apresentados contribuem para o entendimento holístico acerca das leucemias. A transformação leucêmica, seja por mutações primárias nos componentes do microambiente ou pelo sequestro de suas funções normais pelas células iniciadoras de leucemia, é relevante para que ocorra a instalação, a progressão, a disseminação e a quimiorresistência tumoral. Por meio da atuação de vários componentes este microambiente sustenta as células-tronco leucêmicas e representa caminho promissor para o desenvolvimento de novas terapias antileucêmicas.The microenvironment of hematopoietic stem cells is responsible for coordinating several events involved in the production of blood cells. This hematopoietic renewal is only possible thanks to the well-ordered interactions and signals that maintain tissue harmony. In leukemias, the control mechanisms break down and the leukemic transformation of the microenvironment occurs, in order to favor the neoplastic maintenance of blood tissue. The aim of the study was to export the microenvironment transformation process, within the scope of the cellular and molecular changes undergone to support the tumor. It is a narrative review article and as databases Pubmed, Scielo, Cocrahne Library and MedLine were consulted in search of publications in recent years on the subject. The data contribute to a more holistic understanding of leukemias. The leukemic transformation, either by primary mutations in the components of the microenvironment or by the sequestration of its normal functions by the leukemia initiating cells, is relevant for tumor installation, progression, dissemination and chemoresistance. Through the action of various components, this microenvironment supports leukemic stem cells and represents the promising path for the development of new antileukemic therapies

Un estudio de las propiedades estructurales, magnéticas y eléctricas de los compuestos Ba1-xNaxCoO3(x = 0.25, 0.5, 0.75)

Los materiales de tipo cobaltita que presentan transición metal-aislante tienen relevancia en el mercado de la electrónica de consumo. En este trabajo presentamos las propiedades estructurales, magnéticas y eléctricas de las cobaltitas Ba1-xNaxCoO3 (con x = 0.25, 0.5, 0.75). Todas las muestras se sintetizaron mediante un proceso de reacción en estado sólido y su estructura cristalina se determinó a partir de datos de difracción de rayos X (DRX), mediante el método de Rietveld, el cual indicó que las muestras cristalizan en el grupo espacial ortorrómbico C2221 (N.o 20). La microestructura de las muestras sinterizadas se caracterizó mediante microscopía electrónica de barrido (MEB). Las medidas de susceptibilidad magnética confirmaron un comportamiento paramagnético para x ≥ 0.5 en el rango de temperatura estudiado y un pico amplio alrededor de 33 K en la muestra x = 0.25, lo cual es característico de los comportamientos antiferromagnéticos. Las medidas de resistividad permitieron determinar el comportamiento aislante de muestras con x = 0.5 y x = 0.75, mientras que a bajo contenido de sodio (x = 0.25), se observó una transición metal-aislante con temperatura de transición cercana a 105 K. 105 K.Cobaltite-like materials having metal-insulator transitions are relevant in the consumer electronics market. In this work, we present the structural, magnetic, and electrical properties of Ba1-xNaxCoO3 (with x = 0.25, 0.5, 0.75) cobaltite. All samples were synthesized using a solid-state reaction process. Their crystal structure was determined using X-ray diffraction (XRD) data by the Rietveld method, which showed that all the samples were crystallized in the orthorhombic space group C2221 (N.° 20). The microstructure of the sintered samples was characterized by scanning electron microscopy (SEM). The magnetic susceptibility measurements confirmed a paramagnetic behavior for x ≥ 0.5 in the temperature range that was used. Likewise, a broad peak around 33 K in the sample x = 0.25, and characteristic of antiferromagnetic behaviors were observed. On the other hand, resistivity contributed to determining the insulating behavior of samples where x = 0.5 and x = 0.75. In contrast, at low sodium content (x = 0.25), a metal-insulator transition was observed with transition temperature near 105 K