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Background: Endemism can originate from multiple biogeographic and evolutionary processes that promote the formation or persistence of species with restricted distributions (rare species). Understanding rare species’ distributions is a central question in biogeography and is crucial for biodiversity conservation. Questions: What are the rarest plant species in Mexico? How are they distributed? Under what risk categories should they be classified? Studied species: Vascular species considered rare in the flora of Mexico. Study site: Mexico. Methods: “Rare species” were defined as species endemic to Mexico whose distribution is restricted to a single 1 × 1° cell. We analyzed rare species’ distributions and proposed the risk category for each according to IUCN criteria. For some of the species distributed in the cell with the highest number of rare species, we compared the proposed category with published evaluations. Results: We identified 2,705 rare species. The richest cells in terms of rare species are in southern Mexico. Only 302 species had been previously evaluated under IUCN criteria. The remaining 2,403 qualify for the Near Threatened (NT) category or higher. The cell with the highest rare species richness, located in the Sierra Norte of Oaxaca, contained only 10 species with an existing IUCN risk category; for another 81 species, the categories of Vulnerable (VU), Endangered (EN) or Critically Endangered (CR) are indicated. Conclusions: Recognizing the rarity of these 2,705 species will increase attention on them, allowing more precise appraisal of their extinction risk and possible strategies for their conservation.

Background and aims – Endemism may be defined according to the time of origin of taxa. Neo-endemics refer to relatively recent species that have not dispersed outside their ancestral areas. In contrast, paleo-endemics refer to species of ancient origins, which are currently geographically restricted but probably were more widespread in the past. Geographically, endemism areas may also be based on the co-occurrence of more than one species. We aimed to qualitatively identify the neo-endemism and paleo-endemism of endemic Cactaceae of the Tehuacán-Cuicatlán Valley, as well as to quantitatively assess paleo- and neo-endemics areas. Material and methods – Using a dated molecular phylogeny of endemic Cactaceae, we defined paleo- and neo-endemics using an arbitrary boundary of 2.6 million years ago; we also assessed the significance of concentrations of these species using a categorical analysis of paleo- and neo-endemism. Key results – Our results showed that most endemic Cactaceae in the Tehuacán-Cuicatlán Valley arose throughout the Pleistocene, while categorical analysis indicated localised mixed- and super-endemism (including both paleo- and neo-endemics) areas. Conclusion – We suggest that paleo- and neo-endemics, as well as localised mixed-endemism areas, may have originated due to a probable high climatic stability in the Tehuacán-Cuicatlán Valley, which in addition to topographically rugged and ecologically complex zones (e.g. ecotones, isolated habitat patches) may have allowed it to function as a refuge throughout Pleistocene climatic changes, mainly promoting the speciation of neo-endemics, as well as the persistence of relatively few paleo-endemics.

In "Tracing a Long History of International Habitat Coalition Making and Social Production of Housing," Ana Vilenica engages with Enrique Ortiz and Maria Silvia Emanuelli from HIC-AL to explore the evolution of housing justice movements and the role of the Habitat International Coalition (HIC) in advocating for social production of housing. The conversation provides a historical perspective on the coalition's inception. It outlines the foundational moments of HIC, detailing the coalition's growth out of a collective need to address housing as a human right. Enrique shares experiences from the formative years of HIC, where he connected with grassroots movements and organizations across Latin America, fostering a network that would support the social production of habitat. The Conversation highlights the strategic pivot HIC made towards reinforcing a global network that respects regional differences and promotes a common strategy grounded in human rights. It also underscores the need for a collective effort to influence public policy and the necessity of solidarity among various social economy and housing groups.

[Introducción] Pseudotsuga menziesii (Mirb.) Franco es una especie forestal de gran importancia por sus servicios ecosistémicos y su comercialización. Actualmente, se ha documentado que el cambio climático está afectando las poblaciones del norte del continente; sin embargo, no se ha evaluado cómo afectaría esto a la distribución de la especie en el futuro. [Objetivo] El objetivo de este trabajo fue modelar la idoneidad ambiental y la distribución potencial de P. menziesii en 3 periodos (2040, 2060 y 2080). [Metodología] Se estimó la idoneidad y distribución potencial, con base en registros y variables bioclimáticas, con ayuda de MaxEnt; se realizaron transferencias a 2 escenarios de emisiones de carbono en 3 periodos; por último, se evaluó la pérdida de extensión y disminución de idoneidad ambiental en porcentaje. [Resultados] P. menziesii tiene una distribución potencial actual de 164 110 km2, las zonas con mayor idoneidad ambiental (> 0.5) se ubicaron en el norte del país, específicamente en los estados del norte. No obstante, bajo los escenarios de cambio climático, estas áreas sufrieron mayor disminución de la idoneidad ambiental (> 50 %) y se redujo su extensión entre 50.7 % y 92.6 %; en contraste, las poblaciones más resilientes contra el cambio climático fueron las del sur. [Conclusiones] Pseudotsuga menziesii se ve favorecida por las bajas temperaturas, debido a esto, se espera un decrecimiento drástico en su distribución potencial. Aunada a ello, la idoneidad ambiental bajará a más del 50 % en las regiones norte de la nación. Con una pérdida drástica de superficie, la prevalencia de la especie pudiera encontrarse en un punto de declive.

Antecedentes: El noreste de México, estados de Coahuila, Nuevo León y Tamaulipas, constituye una región heterogénea que incluye sierras, planicies continentales y llanuras costeras con una infinidad de ambientes, substratos geológicos y gradientes altitudinales que favorecen la presencia de una rica biodiversidad. No existe una síntesis que documente la diversidad florística de esta región. Preguntas: ¿Cuál es la magnitud de la diversidad de plantas vasculares en el noreste de México?, ¿Cuáles son las familias y géneros con mayor número de especies?, ¿Cómo se distribuye geográficamente esta riqueza florística en toda la región y cuáles son sus elementos más característicos? Especies de estudio: 7,088 especies de plantas vasculares. Sitio de muestreo: estados de Coahuila, Nuevo León y Tamaulipas. Métodos: Se consultó literatura florística-taxonómica sobre la flora de la región y bases de datos de ejemplares para hacer un análisis espacial de la biodiversidad usando celdas de 1° de longitud y latitud. Se calculó la riqueza y el endemismo en la región, los estados y las celdas. Resultados: Para el noreste de México se reportan 7,088 especies de plantas vasculares, de las cuales 1,767 son endémicas de México. Conclusiones: El noreste de México registra una diversidad florística particularmente interesante y compleja, debido a que su territorio se ubica primordialmente fuera del neotrópico y porque constituye el límite boreal para muchos elementos de la flora de México.

Background: Knowledge of endemism in a region (natural or political) is fundamental to determining natural biogeographic regions and establishing conservation priorities. Questions: How many vascular plant species are endemic to the state of Puebla? What is the geographic distribution of endemism in the state? Are there centers of phylogenetic endemism? Studied species: 356 species of vascular plants. Study site: State of Puebla, Mexico. Methods: Based on the literature review and botanical specimens in digitized databases, the vascular plant species endemic or nearly endemic to the state of Puebla, Mexico, was assessed. Using a grid cell 1° × 1° latitude and longitude size, the incidence of each species was assessed. With the above information and a phylogeny of the species, a spatial phylogenetic analysis was carried out to detect centers of phylogenetic endemism. Results: 82.6 % of the 356 endemic species to Puebla are distributed in only one to three grid cells. The spatial phylogenetic analysis revealed centers of high phylogenetic diversity and endemism as well as delineated centers of mixed and paleo-endemism. Conclusions: The state of Puebla contains areas that meet the criteria to be considered centers of species endemism. Strategies toward a better understanding of plant endemism, as here proposed, suggest a better comprehension of the chorology of Mexican endemism, and assess the true role of our natural protected areas in conserving endemic species.

About the neurological manifestations of COVID-19, smell impairment with some distortion or parosmia is currently one of the longest-lasting post-covid sequelae affecting many young adults around the world, we present a case of a 25yo patient that after the COVID-19 infection initiates with anosmia and dysgeusia of difficult control and some weeks later begins with parosmia associated to general discomfort and vomiting preceded by nausea, accompanied by poor oral intake, generating weight loss in 3 weeks, and depression probably related to the clinical profile and the confinement due to the pandemic. She was treated with prednisone, gabapentin, nasal irrigations and olfactory rehabilitation, with mild improvement, which was greater after the second dose of covid-19 vaccine.

Background: The 8th version of the "World Checklist of Vascular Plants" (WCVP) was recently published under the coordination of the Royal Botanic Gardens, Kew. It consists of a list of taxonomic names of species, genera, and families of vascular plants representing the most comprehensive and integrated list available today. Questions: How many accepted species does the WCVP include? Is the quality of the included information acceptable? How has the publication of worldwide species names evolved over time? Does the checklist include the species recorded for Mexico? Studied species: Worldwide species of vascular plants included in the WCVP. Study site: Worldwide and Mexico. Methods: A database was created based on the WCVP to answer the research questions. The number of genera and species by taxonomic status (accepted and synonyms) was quantified, some information quality tests were carried out, and the potential number of undiscovered species in the world was estimated using non-parametric techniques. Results: The WCVP contains 1,233,172 names, of which 418,737 are accepted. It is estimated that around 25 % more unknown species remain to be discovered in the world. The quality of the information contained in the WCVP is quite reliable and complete; only 3 % of Mexican species are not included in the WCVP. Conclusions: The WCVP synthesizes current taxonomic knowledge in an integrated manner and is useful for systematic and automated analyses. At the country level, at least for Mexico, it stands as an important reference source when attempting to understand and evaluate floristic knowledge.

Background: Different regionalizations have been proposed for the Sierra Madre Oriental (SMOR), but none of them have analyzed its full floristic diversity. Hypothesis: The geographical distribution of the vascular plant species of the SMOR allows the identification of floristic regions with unique species that identify them as biogeographic units. Studied species: Vascular plants. Study site: Sierra Madre Oriental physiographic province, Mexico. Methods: Plant species distribution was analyzed in 1 × 1° latitude and longitude grid cells. Characteristic species (those with half or more of their known geographical distribution in Mexico in the SMOR) were identified, and a classification method was applied to distinguish biogeographic regions. Results: 8,472 species were recorded in the Sierra Madre Oriental, 3,433 of them considered characteristics, of which 2,158 are endemic to Mexico and 585 are considered strictly endemic to the province. The portions of the SMOR in the states of Coahuila, Nuevo León, Tamaulipas, and San Luis Potosí have a higher species richness and this richness decreases towards the south of the province. Five floristic districts were identified within the SMOR. Conclusions: The phytogeographic analysis carried out and its comparison with other regionalizations shows there is still disagreement in the biogeographic delimitation of the Sierra Madre Oriental and to achieve this goal it is necessary to include neighboring provinces in the analyzes, which will allow to identify their unique species and define their biogeographic limits in a more precise way.

Background: Sites of overlap in the species distribution among regions are known as transition zones. Their floristic and biogeographic complexity is rarely discussed. Questions: Is it possible to identify transition zones amid the biogeographic provinces of Mexico? Can transition zones also be considered areas of endemism? Study species: 315 Asteraceae taxa endemic to Mexico. Study site: Volcanic Belt, Balsas Depression and Sierra Madre del Sur biogeographic provinces. Methods: For species of Asteraceae endemic to three biogeographic provinces of central Mexico, we characterized the province to which each species belonged and estimated the distance it could penetrate the neighboring province. We defined transition zones between biogeographic provinces as the average penetration distances of the species. We also evaluated the presence of species with restricted distribution to transition zones. Results: Two transition zones were identified in the Balsas Depression, first, at the junction with the Volcanic Belt with a width of 13 km, and second, with the Sierra Madre del Sur, with a width of 12.3 km. There were 45 species whose distribution was restricted to those transition zones. Conclusions: Understanding how richness and endemism are exchanged from one region to another is essential to explain how their floras have been assembling and evolving. This analysis has allowed us to better understand the relationships among regions as complex as those studied here.

Background: Dichrocephala is an Old-World genus of the tribe Astereae within the family Asteraceae. One species, D. integrifolia, has been recently reported as introduced in the New World from a pair of collections from Guatemala. During field work in the state of Chiapas in southern Mexico, the species was found and collected. This is the first record of both the genus and species in Mexico and the second record for these taxa in the Americas. Question: Can D. integrifolia occur in more areas in the New World besides those known from Guatemala and Chiapas? Studied species: Dichrocephala integrifolia Study site and dates: Mexico, Central America, and the Caribbean. Methods: An ecological niche model was made and it was projected into the New World. Results: The ecological niche model predicts the records of D. integrifolia in the New World in addition to other ecologically suitable areas, mostly in pine-oak forests in Mexico and Central America and zones with humid mountain and pine forest in the Caribbean. Moreover, a morphological description and illustrations of the species are provided to help with its identification. Conclusions: It is desirable to avoid the further spreading of D. integrifolia in the New World. Although this species is not considered as invasive, it seems to have a high dispersal potential and the ecological niche modelling indicates larger regions in the Americas that might be affected.

Background. Agroforestry Systems (AFS) are natural resource management practices of peasant families; their importance is due to the various benefits and environmental functions they generate. However, the pressures of agricultural modernity, changes in land use, and climate change are factors that are affecting their structure, functions, and benefits. Objective. Determine the degree of peasantity or agroindustry of the AFS of San Andrés Calpan, Puebla, Mexico. Methodology. A survey was applied in 2018 to a sample of 81 producers with corn systems interspersed in fruit trees. A peasantity-agroindustry index (PAI) was constructed based on eight attributes. Resultados. Three groups of producers were formed, according to their PAI: pure, traditional, and semi-traditional peasant. Fisher's test and analysis of variance were applied to determine differences between groups. A PAI of 0.23. By group, 59% of the AFS presented semi-traditional, 22% traditional, and 19% pure peasant characteristics. Implications. Indicators showing significant differences were surface area, labor origin, productive energy, productive self-sufficiency, and beliefs. Conclusion. The AFS preserve the social, ecological, and economic bases of peasant management.

Biogeographic regions are defined by taxa with similar distribution patterns. Flowering plants have been widely used to propose biogeographic regionalization schemes because of shared historical or ecological factors that determine their distribution. The Mexican Transition Zone represents the boundary between the Nearctic and Neotropical kingdoms; however, there is no general agreement about the limits and extent of this region. Despite the significance of its role in the history of Mexican biota, no study involving a set of relevant plant taxa validates the magnitude of the Mexican Transition Zone. This work attempts to determine the proportion of flowering plant families and genera that characterize the biogeographic kingdoms and the Mexican Transition Zone. Through identification of distinctive genera it is shown that the Mexican Transition Zone includes the mountains of Mexico, from Oaxaca northwards. The results provide a broad view of the distribution patterns of the flora of Mexico and allow the evaluation of relationships and floristic affinities.

No es sencillo concretar el alcance de la prohibición constitucional de que el sistema tributario tenga alcance confiscatorio. No obstante, el derecho constitucional a la propiedad constituye un límite al poder tributario. La carga tributaria que actualmente soporta la energía nuclear justifica reflexionar nuevamente sobre dicha prohibición. La existencia de tasas que cubren los costes de gestión y almacenamiento de los residuos radiactivos, junto a la ausencia de carácter extrafiscal de los Impuestos creados por la Ley 15/2012, pueden suponer una vulneración del principio de igualdad y producir un efecto confiscatorio.

The importance of partnerships is critical in educational arenas, but information on how partnerships form with the involvement of corporations, districts, and universities working in harmony is limited in the current literature. The teacher preparation program described in this paper is a “built-to-last” partnership model with over 650 teachers prepared to be teacher-leaders in science, technology, engineering, and mathematics (STEM) education. The authors provide a history of the program’s development, the sustainability of the program over time, the content of the various components of the partnership, and the evolution of the program, including its current status.

Background: The Hinton family comprises three generations of plant collectors that have made an important contribution to the knowledge of the flora of Mexico. They have collected in 13 Mexican states and have provided material for the description of 8 genera and about 555 species new to science. Question: What is the contribution of the collections of the Hintons to our knowledge of the flora of Mexico? Where was their main collecting effort and how many species have been recorded? Species study: Vascular plants Study site: Mexico Method: Different national and foreign databases were consulted and a list of species collected by the Hintons was obtained. The records were reviewed to eliminate synonymy and a complete list of species and their distribution by states was compiled. Results: A total of 28,947 records were obtained and 25,717 of them were identified to species level. In addition to the family's collection, the herbaria with the largest number of records are LL-TEX, K, IEB, and MEXU. The records come from about 2,752 different collecting localities throughout Mexico and account for 5,730 species, 1,573 genera, and 233 families. Conclusions: Many of the specimens collected by the Hintons come from areas that are still underexplored today. The contribution of the Hinton family to the knowledge of the flora of Mexico represents an important legacy and their collections constitute an enduring source of information for people interested in the flora of Mexico.

Background: Ageratina, with 167 species, constitutes the most diverse genus of the Mexican Asteraceae and the sixth most diverse of the vascular plants in Mexico. The taxonomy of the genus is complex, due to its number of species and the numerous inadequately delimited taxa or with intricate and confusing nomenclature. In addition, little known species have sometimes remained under the synonymy of another different species, as in the case of A. rivalis, which has been considered as a synonym of A. grandifolia. Question: Is it possible to recognize Ageratina rivalis as a distinct species of A. grandifolia by critically analyzing its circumscription, nomenclature and geographical distribution? Taxon: Ageratina grandifolia and A. rivalis. Study site: Mexico. Method: A thorough review of herbarium specimens, field material, descriptions and geographic distribution of the species was made to contrast them. Results: Several differences exist in the morphology and geographical distribution of Ageratina rivalis and A. grandifolia. Descriptions, pictures, distribution maps, synonymy and a key to distinguish them from similar species are provided. The presence of A. grandifolia in Mexico City is also documented. Lectotypes are designated for Eupatorium conspicuum, E. conspicuum var. pueblense, E. grandifolium, and E. rivale. Conclusions: Morphology and geography support the distinction between A. grandifolia and A. rivalis. However, further research is desirable to corroborate or refute this statement, and especially to clearly circumscribe several similar species that seem to be related. This work contributes to a better understanding of the taxonomy and biogeography of the genus Ageratina in Mexico.

A ntes de realizar el modelado de la distribución potencial de una especie, se recomienda ha - cer una preselección de covariables pues la redundancia o variables irrelevantes pueden in - ducir sesgos en la mayoría de los modelos. En este estudio, se propuso un método automati - zado para la selección a priori de covariables utilizadas en el modelado. Se emplearon cinco especies típicas de la flora mexicana ( Catopheria chiapensis, Liquidambar styraciflua, Quercus martinezii, Telanthopora grandifolia y Viburnum acutifolium ) y 56 covariables ambientales. Se generaron matrices de presencia-ausencia para cada especie y se analizaron empleando regresión logística; el modelo resul - tante de cada especie se evaluó mediante un remuestreo bootstrap. La distribución de las cinco especies se modeló usando el algoritmo de máxima entropía y con el empleo de tres conjuntos de covariables ambientales. La precisión de los modelos generados se evaluó con intervalos de confianza de cada curva característica operativa del receptor (COR). Los intervalos de confianza de las curvas COR resultantes no mostraron diferencia significativa ( P < 0.05) entre los tres modelos predictivos generados; sin em - bargo, el modelo más parsimonioso se obtuvo con el método propuesto.

El rastrojo de maíz es un subproducto importante para la alimentación de varias especies pecuarias en unidades de producción bajo condiciones de temporal de los valles altos de México. En estas zonas se carece de variedades que produzcan en suficiencia grano y rastrojo (variedades de doble propósito); por lo que en el presente estudio se evaluó la producción de rastrojo y grano de variedades locales de maíz en los valles altos de Puebla y Tlaxcala, México. Se colectó semilla en las regiones Libres-Mazapiltepec-Huamantla (L-M-H) y Serdán-Tlachichuca-Guadalupe Victoria (S-T- GV). Para cada región se evaluaron 144 variedades, incluyendo cuatro testigos comerciales, en dos localidades bajo un diseño látice simple 12x12 con dos repeticiones. Se midió rendimiento de rastrojo, producción de hoja y tallo, altura de planta y de mazorca, días a floración femenina, y rendimiento de grano. En cada experimento se realizó un análisis de varianza y por cada región un análisis combinado además de un análisis de correlación canónica. En cada región se encontró una diversidad amplia para rendimiento de rastrojo y grano (P

En el estado de Puebla, la región más importante en producción de maíz (Zea mays L.) para elote es Tehuacán. Las variedades usadas son principalmente poblaciones nativas, de las cuales se desconoce su potencial para la producción de elote y la calidad del mismo. El objetivo de esta investigación fue evaluar agronómicamente un conjunto de poblaciones nativas de maíz colectadas en Tehuacán, para determinar su variación en rendimiento y calidad de elote. En 2009 se evaluaron 100 variedades en tres localidades bajo condiciones de riego, de las cuales 95 fueron colectadas en el área de Tehuacán. Las cinco restantes fueron dos variedades mejoradas y tres testigos raciales de Bolita, Celaya y Pepitilla. Se midieron 20 variables de planta y elote. Los resultados del análisis de varianza combinado mostraron en todas las variables evaluadas, excepto en una, diferencias altamente significativas (P ≤ 0.01) entre variedades, lo que indica la presencia de diversidad para tales características entre los maíces nativos estudiados. En rendimiento de elote, un grupo de 16 poblaciones nativas resultó sobresaliente (P ≤ 0.05). La variedad local TEH77 obtuvo el mayor número de características deseables para rendimiento y calidad de elote: rendimiento promedio de 9,576 kg·ha-1, 11.3 °Brix, 13.7 cm de longitud de mazorca, 5.5 cm de ancho de mazorca y 30.7 granos por hilera. Esta variedad superó al mejor híbrido comercial ‘AS900’ en 52, 23, 30, 33 y 47 % en rendimiento (kg·ha-1), contenido de sólidos solubles totales (°Brix), longitud y diámetro de mazorca (cm), número de hileras y granos por hilera, respectivamente.

Con base en ejemplares de herbario recolectados, identificados y georreferenciados provenientes del territorio considerado por el proyecto Flora del Bajío y de regiones adyacentes, se analiza la riqueza de Asteraceae conocida en dicha región. Utilizando una división de la región en cuadros de 0.5° x 0.5°, el objetivo fue identificar los sitios de alta diversidad para la familia. La región tiene documentadas, con los ejemplares de herbario revisados, 681 especies de Asteraceae, distribuidas en 182 géneros; aquellos con mayor número de especies son Ageratina (39), Stevia (31), Verbesina (29) y Acourtia (27), mientras que 82 registran una sola. En promedio se encontró una proporción de 3.7 especies por género. Querétaro es la entidad federativa que más especies registró (504), seguida de Michoacán (490) y Guanajuato (389). Análisis estadísticos proyectan la existencia de 773 especies para la región de estudio, de las cuales se han registrado 681 (88% de las especies esperadas; de ese porcentaje faltante, al menos 66 (67%) han sido reportadas de alguna parte del Bajío y regiones adyacentes, pero hasta la fecha no se han observado ejemplares de herbario que respalden su presencia. Se evalúa la riqueza por cuadro y se proponen algunos considerados importantes para llevar a cabo futuras estrategias de conservación con base en los patrones de riqueza encontrados.

Las posibles implicaciones en el Impuesto sobre Sociedades de las normas internacionales de contabilidad, elaboradas en el seno de una corporación privada e incorporadas al Derecho Comunitario a través del procedimiento de «comitología», ofrecen diferentes perspectivas de análisis, sobre todo ante una futura armonización de la base imponible societaria. Entre los aspectos institucionales que plantean, ya en la actualidad, esas normas internacionales destaca su discutible compatibilidad con la garantía que subyace a la institución de la reserva de ley tributaria, es decir, el principio democrático de autoimposición y la función que el mismo cumple en el ordenamiento comunitario.

The dynamic behavior of clamped-clamped straight pipes conveying gas-liquid two-phase flow is theoretically investigated, specifically the effect of the flow parameters on the frequency of the system. First, the equation of motion is derived based on the classic Païdoussis formulation. Assuming Euler-Bernoulli beam theory, small-deflection approximation and no-slip homogeneous model, a coupled fluid-structure fourth-order partial differential equation (PDE) is obtained. Then, the equation of motion is rendered dimensionless and discretized through Galerkin’s method. That method transforms the PDE into a set of Ordinary Differential Equations (ODEs). The system frequency is obtained by solving the system of ODEs by allowing the determinant to be equal to zero. System frequencies for different geometries, structural properties and flow conditions have been calculated. The results show that the system frequency decreases with increasing two-phase flow velocity. By contrast, the former increases with increasing homogeneous void fraction. These theoretical results are in agreement with experimental findings reported in the literature. Furthermore, even for typical two phase flow conditions, the system can become unstable for inadequate chooses of geometry or material of the pipe.

La Ley 35/2006 confiere al Impuesto sobre la Renta de las Personas Físicas un carácter marcadamente analítico en que las rentas integrantes de la base imponible del ahorro se benefician de un tipo proporcional del 18 por 100. La reforma se sitúa en un contexto de competencia fiscal internacional muy intensa que ha inducido a algunos Estados de nuestro entorno a dar un tratamiento de favor a las rentas del capital. Nuestro IRPF se asemeja en algunos aspectos a los «modelos duales» tempranamente implantados por los países escandinavos. En el trabajo se analizan tanto los argumentos que se han empleado para justificar este cambio de paradigma como los problemas constitucionales que plantea.

We analyzed the species richness of the grass family (Poaceae) in the state of Coahuila, Mexico, evaluating data from herbarium specimens. The evaluation was made by dividing the state into a grid of 20’ × 20’ squares (latitude × longitude), the objective was to identify areas of high species diversity. The herbaria revision documented 39 species of grasses, distributed in eight subfamilies, 19 tribes, and 97 genera. The genera with the highest number of species are Muhlenbergia (32 species), Bouteloua (21), and Eragrostis (18). Seven species are endemic to Northeastern Mexico (Bromus densus, Bouteloua eriostachya, B. johnstonii, Calamagrostis coahuilensis, Festuca coahuilana, F. valdesii, and Poa wendtii) and, 58 species, plus one subspecies and one variety are rare. Because arid areas cover a larger portion of the state, the subfamily Chloridoideae is dominant with 125 species. The subfamily Panicoideae has a record of 87 species and is mainly present in humid regions, while the Pooideae is abundant in the mountain regions of southeast and northwest, and includes 86 species. We evaluated the species richness for each grid square and propose some of these as important areas to carry out future conservation projects.

Urban road dust can be enriched in different elements and hence it can pose a threat to human and environmental health. Proximal soil sensing allows the swift monitoring of such particles in order to drive attention to any possible risks. The goal of this study is to find the variation in concentrations found when using a portable X-ray fluorescence (XRF) proximal sensor for the determination of metals in road dust with different degrees of sample pretreatment. In general, although results are element dependent, sieving samples to a particle size of

El rastrojo de maíz es un subproducto importante para la alimentación de varias especies pecuarias en unidades de producción bajo condiciones de temporal de los valles altos de México. En estas zonas se carece de variedades que produzcan en suficiencia grano y rastrojo (variedades de doble propósito); por lo que en el presente estudio se evaluó la producción de rastrojo y grano de variedades locales de maíz en los valles altos de Puebla y Tlaxcala, México. Se colectó semilla en las regiones Libres-Mazapiltepec-Huamantla (L-M-H) y Serdán-Tlachichuca-Guadalupe Victoria (S-TGV). Para cada región se evaluaron 144 variedades, incluyendo cuatro testigos comerciales, en dos localidades bajo un diseño látice simple 12x12 con dos repeticiones. Se midió rendimiento de rastrojo, producción de hoja y tallo, altura de planta y de mazorca, días a floración femenina, y rendimiento de grano. En cada experimento se realizó un análisis de varianza y por cada región un análisis combinado además de un análisis de correlación canónica. En cada región se encontró una diversidad amplia para rendimiento de rastrojo y grano (P

El estado de Nayarit se ubica en una posición geográfica estratégica al encontrarse en el vértice de tres importantes cadenas montañosas del país (Eje Volcánico Transversal, Sierra Madre Occidental y Sierra Madre del Sur), lo que determina en gran medida su alta riqueza florística. En la entidad, la familia Asteraceae, representada por 122 géneros y 447 especies, es la más diversa de todas las fanerógamas. En este trabajo se presenta una lista actualizada de las especies de Asteraceae; asimismo, se compara su diversidad con la de otros estados vecinos. Se presenta igualmente una lista de las especies endémicas a Nayarit.

Humid Mountain Forest is one of the most important Mexican biomes due to the high floristic richness and endemism found within its small geographical extension. The distribution of this biome is not well known in the country; accordingly, the goal of this paper is to delimit its distribution by using potential distribution models of species characteristic to the biome as surrogates. Based on herbarium specimens housed at the National Herbarium of Mexico, a database of 78 species restricted or mostly restricted to Humid Mountain Forest was constructed. In addition, 56 environmental covariates (26 climatic, nine soil properties, nine topographic attributes, and 14 remote sensing data) were assembled. Species modeling was done using MaxEnt. Twenty-three covariates defined the Humid Mountain Forest distribution in Mexico. Among these, normalized vegetation index for May, total annual precipitation, and organic carbon content in the soil were the most important. According to the models, Humid Mountain Forest in Mexico represents 7% of the total surface of the country and it is found in 25 of the 32 states. Chiapas, Guerrero, Michoacán, and Oaxaca are the most outstanding states since they collectively account for 74% of the total Humid Mountain Forest surface.

El bosque humedo de montana, tambien conocido como bosque mesofilo de montana o cloud forest, esta definido y limitado por la presencia persistente de nubes y neblina que, ademas de la lluvia, capturan las gotas de agua que se condensan sobre la vegetacion. Se reconoce ampliamente que la humedad atmosferica es el principal factor ambiental que promueve la persistencia y distribucion de este tipo de vegetacion en el mundo. Sin embargo, se carecen de analisis correlativos entre riqueza de especies del bosque humedo de montana y los factores ambientales a escalas amplias. Es de suponer que tal riqueza tiene su base en la hipotesis correlativa con variables ambientales contemporaneas, principalmente con la triada altitud-clima-suelo. El objetivo fue analizar e identificar que variables ambientales tienen asociacion significativa y cuales son las mas importantes en la prediccion de la riqueza de especies del bosque humedo de montana. Los sitios con bosque humedo de montana se ubicaron en 61 celdas de 1o latitud × 1º longitud. Mediante sistemas de informacion geografica se generaron capas ambientales que incluyeron variables bioclimaticas, de estacionalidad climatica, un modelo digital de elevacion y variables edaficas. Los resultados indican que 58% de la variacion en la riqueza de especies del bosque humedo de montana se relaciona con cinco variables: la precipitacion pluvial de los meses húmedos del ano, la altitud, la evapotranspiracion real anual, la estacionalidad de la precipitacion y el carbono organico en los suelos. En el bosque humedo de montana de Mexico existe una asociacion consistente entre la riqueza de especies y las expresiones categóricas de la relacion agua-energia.

This article presents an original puzzle that supports students' development of visual thinking and geometry ideas based on the Van Hiele levels of geometric thought. The "Triangle Puzzle" is one of many tools teachers can use to guide students' learning of geometry. The Van Hiele's theory provides a way to assess and support this learning. Students need opportunities to actively construct their understanding of concepts using representation and visualizations.

Se estimaron los patrones de riqueza en México de cuatro tribus de la familia Asteraceae del país que recientemente han sido revisadas (Mutisieae, Senecioneae, Tageteae y Vernonieae) mediante extrapolación, utilizando datos de las etiquetas de ejemplares de herbario. Se utilizó el método de estimación de riqueza no paramétrico ICE (“Incidence-based Coverage Estimator”), el cual se basa en datos de presencia-ausencia de las especies por área. Se evaluaron 553 especies, que representan 18.3% de la riqueza de Asteraceae presente en México, representadas por 24,304 registros de herbario recolectados en 14,714 diferentes localidades. La información fue analizada dividiendo al país en cuadrículas con celdas de 1° de latitud y longitud y con celdas de 0.5°. Se identificaron las celdas con alta riqueza conocida (hot spots), así como aquellas que la extrapolación sugiere que contienen una alta riqueza estimada. Se determinaron las que parecen ameritar mayor atención en futuros trabajos de exploración, utilizando las diferencias entre la riqueza estimada y la observada para cada celda, con base en el supuesto teórico de que el valor estimado es más cercano al valor real.

Citrus wilt is a disease of recent appearance in the northern area of Veracruz that causes economic losses to producers in the region. The present work aimed to identify the causative agent of this disease and evaluate different fungicides to determine its in vitro sensitivity. A fungus was consistently isolated in plants with wilt symptoms; it was morphologically identified in different culture media and molecularly identified by PCR using the EF1-728F/EF1-986R primers. The fungus was inoculated in three varieties of citrus under greenhouse conditions. The sensitivity test was carried out with the fungicides chlorothalonil, benomyl thiabendazole, prochloraz, and a biological agent (Bacillus subtilis) at different concentrations, plus a negative control. Fusarium sp. (Accession No. MW438335) was morphologically and molecularly identified as the causal agent of vascular wilt in citrus fruits, causing growth retardation, decreased number of roots, wilting of the apical bud, and necrosis in the vascular system of the three varieties inoculated. The most effective fungicides in inhibiting mycelial growth were thiabendazole, prochloraz, and the biological agent Bacillus subtilis. [ABSTRACT FROM AUTHOR]

Campylobacter spp. and Arcobacter butzleri are foodborne pathogens associated with the consumption of contaminated raw chicken meat. At the industry level, the combination of new and common antimicrobials could be used as a strategy to control the presence of pathogens in chicken carcasses. The objective of this study was to determine the bacteriostatic and bactericidal effects of a mixture of chlorine (Cl) and sodium gallate (SG) on a mixture of two Campylobacter species (Campylobacter jejuni and Campylobacter coli) and A. butzleri. Using a central composite experimental design, it was established that the optimum inhibitory SG-Cl concentration for Campylobacter spp. was 44 to 45 ppm. After 15 h of incubation, Campylobacter species growth was reduced by 37.5% and the effect of Cl was potentiated by SG at concentrations above 45 ppm. In the case of A. butzleri, optimum levels of 28 and 41 ppm were observed for SG and Cl, respectively; no synergism was reported, as this bacterium was more sensitive to lower Cl concentrations than Campylobacter. After a 20-min pretreatment with peracetic acid (50 ppm), the optimum condition to achieve a >1.0-Log CFU/mL reduction of Campylobacter spp. was exposure to 177 ppm of Cl and 44 ppm of SG for 56 min. As A. butzleri showed lower resistance to the bacteriostatic effect of the Cl-SG combination, it was assumed that optimum bactericidal conditions for Campylobacter spp. were effective to control the former; this was confirmed with subsequent validation of the model. The SG-Cl combination has bactericidal properties against Campylobacter and A. butzleri, and it may be a useful strategy to improve sanitary practices applied in the poultry industry. [ABSTRACT FROM AUTHOR]

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