University of Puerto Rico at Mayagüez Institutional Repository
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Publication Diversity of cryptic and active ciliates in a hypersaline pond in Puerto Rico: The effect of salinity gradients(2024-12-06)Cabo Rojo National Wildlife Refuge is a threatened ecosystem largely composed of hypersaline lagoons and soil flats (Puerto Rico). Despite studies addressing its microbial communities, ciliates and the role they play in these habitats have been poorly understood. Therefore, we aimed at assessing the ciliate community structure (species richness and composition) and the effects of environmental factors through spatiotemporal scales (four sites and two seasons) within a hypersaline lagoon (44325 ppt). Community patterns were addressed with metabarcoding (V4 region, 18S rDNA), morphological methods, and a dilution microcosm experiment. Seasonal variation was shown for species richness and composition across the four sites. Remarkably, three morphospecies - Trimyema sp. 1, Chilophrya sp., and a scuticociliate - were found in the highest salinity sites (325 ppt). Composition patterns were shown to differ among sites, with central sites (2 and 4) showing more similarities compared to the extreme ones (1 and 3), suggesting that ciliates are acting as bioindicators of environmental conditions in this lagoon. Species richness was best predicted by temperature and salinity showing a significant negative effect. Surprisingly, these parameters displayed a significant interaction. Also, these factors and AFDM were significant in driving the community composition across environmental gradients. Simulating abrupt changes in salinity and its isolated effect on the community showed a negative relationship between salinity and species richness and different composition groupings along the salinity gradient. These results were consistent with field studies suggesting that ciliates from the lagoon are adapted to these disturbances. The models built from this ecosystem could serve to increase our understanding of microeukaryotes and their interactions with abiotic factors in other hypersaline lagoons across the world. Finally, this study has shed light on the ciliate community patterns across spatiotemporal scales and physicochemical parameters that characterize this tropical ecosystem. Consequently, these insights can be used for conservation efforts and to predict future climatic scenarios that could deteriorate this diverse and unique environment.Publication Evaluación de cítricos protegidos de vectores del Huanglonbing y el virus de la tristeza de los cítricos en Sabana Grande(2025-05-19)En 2018, Puerto Rico experimentó una baja producción de cítricos, similar a otras regiones productoras en el mundo, debido al impacto del Huanglongbing (HLB) y el virus de la tristeza de los cítricos (CTV), lo que ha limitado significativamente la producción. El HLB, asociado con la bacteria Candidatus Liberibacter asiaticus (CLas), fue reportado por primera vez en Puerto Rico en 2009, y su vector, Diaphorina citri, fue identificado en 2001. El CTV se detectó en 1992 y es endémico en la isla. Todas las variedades de cítricos son susceptibles al HLB y no existe un tratamiento completamente efectivo. Para evaluar estrategias de manejo de HLB y CTV, se llevó a cabo un experimento en la finca La Plata, Sabana Grande, utilizando la variedad Tahiti (Citrus x latifolia) sobre patrón Cleopatra (Citrus x reshni). Se compararon tres tratamientos (químico, orgánico y malla protectora) con un control. A los 10 meses, el monitoreo visual mostró presencia del psílido asiático en los árboles del control, pero una baja incidencia en los protegidos con malla. La prueba de PCR reveló que los árboles bajo la malla tuvieron una menor prevalencia de CLas en comparación con otros tratamientos. Para CTV, la prueba TAS-ELISA confirmó su presencia en todos los tratamientos. Los árboles bajo la malla alcanzaron mayor tamaño y volumen, lo que sugiere que la malla no solo redujo la incidencia del vector del HLB, sino que también favoreció el crecimiento al crear un microclima más favorable.Publication La escena de lectura del socialismo libertario en Puerto Rico: Un estudio panorámico sobre la lectura en los talleres de tabaco, los centros de estudios sociales y la huelga general de 1917(2025-05-16)This study reviews primary texts on workers’ notions of education and reading and their relationship to libertarian socialism and strikes in Puerto Rico at the beginning of the twentieth century. The practice and ideologies in the scenes of reading of libertarian socialism manifest the modes and purposes with which workers approached texts. The concept of group reading in Puerto Rico has an international genealogy, with links to reading in tobacco factories in Cuba and their Caribbean and transatlantic dispersions. The history of the practice in the tobacco factories from its origins demonstrates how worker’s practices of reading were influenced by international anarchism under the concept of self-education. The ideological development of the collective of workers and its assumption of education culminated in the Centers for Social Studies. This study narratively reconstructs the general strike in the tobacco factories in Ponce in 1917 to demonstrate how it was provoked by the prohibition of reading and reviews the newspaper Unión Obrera and publications of the tobacco workers to show how it was resolved.Publication Molecular and morphological support for the synonymy of 𝘕𝘦𝘱𝘩𝘳𝘰𝘴𝘵𝘰𝘮𝘶𝘮 and 𝘗𝘢𝘵𝘢𝘨𝘪𝘧𝘦𝘳 including the discovery of a new species and broad geographic connections(2025-05-16)This study examines the taxonomy, distribution, and evolutionary relationships between Patagifer Dietz, 1909 and Nephrostomum Dietz, 1909 (Digenea: Echinostomatidae), parasites known from avian hosts. Through morphological analyses, targeted sequencing of nuclear (28S, ITS2) and mitochondrial (Cox1, Nad1) markers, as well as sequencing of the mitochondrial genome, this study provides robust evidence that Nephrostomum and Patagifer form a single, well-supported clade. Consequently, Nephrostomum should be considered a junior synonym of Patagifer. While rDNA markers exhibited minimal variation—and sometimes led to erroneous species identifications—mitochondrial genes have been found to resolve distinct lineages and clarify species boundaries. Notably, Patagifer ramosum, native to the Old World, was confirmed in both Africa and the Americas. Similarly, P. bilobus also appears to be widely distributed in Europe and the Americas. Among the newly examined parasites, one specimen identified from the Plumbeous ibis, Theristicus caerulescens, from Argentina was genetically and morphologically distinct from all other parasites examined and represents an undescribed species. Overall, these findings underscore the importance of integrating morphological and molecular data in taxonomy, highlight the potential for migratory birds to disperse parasites across continents, and underscore how morphological differences can misrepresent genetic diversity.Publication Broadband array architectures for reducing antenna noise temperature(2025-05-16)Passive remote sensing applications rely heavily on precise measurements, thus necessitating the mitigation of interference and noise. This study proposes a method for measuring noise performance for an arbitrary antenna array receiver system. This is achieved by analyzing four key areas: low noise amplifier design, antenna design, array design, array representation as a multi-port network, and receiver design. By altering the characteristics of each of these areas we can measure the resulting noise of the receiver system and understand the benefits and disadvantages of each. This method offers valuable insights for the optimization of receiver systems with regards to noise mitigation and can serve as a method of noise performance study for future and existing architectures.
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