Valley Of Mexico Research Articles

Determinants of transport mode choice in metropolitan areas the case of the metropolitan area of the Valley of Mexico

The following paper examines the determinants of transport mode choice for trips in the Metropolitan Area of the Mexican Valley. Using a data set from the Mexican household travel survey (Encuesta Origen - Destino) conducted in 2017 and multinomial logistic regression, the influence of transportation supply, spatial characteristics and socio-economic factors on individual mode choice is estimated. To our knowledge, this is the first analysis of mobility behaviour in the Metropolitan Area of the Mexican Valley with this newly developed data set.The main findings show that a better Mass Rapid Transit infrastructure is not consistently positively associated with the likelihood of using this service. While a better road infrastructure is promoting the use of Mass Rapid Transit services over driving, it is negatively linked with the likelihood of walking and bicycling. These slow modes are mainly interfered with the distance to the city centre: the further away from the centre, the higher the likelihood of walking and bicycling instead of using the car.With respect to socio-economic characteristics of individuals, women and the young found to have a higher likelihood of using public transport than the car. In contrast, having children is negatively associated with the likelihood of using public transport. Moreover, a higher education of individuals is found to be positively associated with car use, while car availability is negatively associated with all other transport mode options.

Trends in Temperature Extremes in Selected Growing Cities of México Under a Non-Stationary Climate

Mexico is vulnerable to extreme climatic events; however, their impact is not uniform in all the country. This study presents an analysis of extreme temperatures in 12 Mexican cities, modeled under the assumption of a non-stationary climate. Temporal trends were estimated from an available climatological base of maximum and minimum temperatures with the non-parametric tests of Mann-Kendall and Sen’s slope method, and a generalized extreme value (GEV) distribution was used to model both temperatures. A likelihood ratio test and Akaike and Bayesian information criteria were used to evaluate the optimal model choice with incorporation of a covariate. Using the best model, return levels and confidence intervals for future scenarios were estimated. A trend towards urban warming was detected from both the non-parametric tests and the GEV distribution, although with heterogeneous behavior. In the series of the maximum temperatures, half of the cities analyzed were non-stationary, and of those, the city of Guadalajara, located in the center-west of the country had a negative trend. The trend for minimum temperatures was more uniform, as 90% of the cities were non-stationary with a positive trend, and only 10%, in an urban area to the east of the metropolitan area of the Valley of Mexico (Milpa Alta) and a coastal city of the Gulf of Mexico (Veracruz), showed stationary series. It is therefore concluded that return periods of thermal extremes estimated in a changing climate temporarily showed a significant variation, so statistical modeling must consider this behavior due to its importance for risk assessments and adaptation purposes.

Evaluación del transporte público en el Estado de México. El caso del Mexibus

El desarrollo del capitalismo no se explica sin la evolución del transporte, y viceversa. Sin embargo, la gobernanza en países subdesarrollados, como México, se enfrenta a una crisis económica y urbana permanente, que limita los alcances de las políticas públicas del transporte urbano. Durante la última década, el origen y evolución del sistema Mexibús, en el Estado de México, responde a la creciente necesidad de movilidad que diariamente enfrentan más de 10 millones de mexiquenses de los municipios conurbados de la Zona Metropolitana de la Ciudad de México (ZMCM). A casi una década de la puesta en operación de la primera línea del sistema de transporte público (Bus Rapid Transit, por sus siglas en inglés), resulta conveniente evaluar el impacto económico y social que ha tenido entre los habitantes del Valle de México.

Projected Landscape Impacts from Oil and Gas Development Scenarios in the Permian Basin, USA.

Projecting landscape impacts from energy development is essential to land management decisions. We forecast landscape alteration resulting from oil and gas well-pad construction across the economically important Permian Basin of Texas and New Mexico, USA, by projecting current landscape trends through 2050. We modeled three landscape-impact scenarios (low, medium, and high) using recent (2008-2017) trends in well-pad construction and energy production. The results of low-, medium-, and high-impact scenarios suggest that ~60,000, ~180,000, and ~430,000 new well pads could be constructed, potentially causing ~1000, ~2800, and ~6700 km2 of new direct landscape alteration. Almost two-thirds of all new well pads will be constructed within the geologic boundaries of the Delaware and Midland Basins. This translates into a 40, 120, and 300% increase in direct landscape alteration compared with direct alteration from existing well pads. We found that indirect effects (from edges) could increase by twofold, and that the ratio between indirect and direct alteration could decline by half as alteration intensifies and overlaps with existing alteration. The Chihuahuan Desert occupies the largest portion of the study area, and is projected to experience the largest area of alteration from future well-pad construction in the Permian Basin; the degree of direct alteration could increase by 70, 200, and 500% in this desert region, under low-, medium-, and high-impact scenarios. These scenarios can be used to design proactive conservation strategies to reduce landscape impacts from future oil and gas development.

Moisture Attribution and Sensitivity Analysis of a Winter Tornado Outbreak

AbstractThe tornado outbreak of 21–23 January 2017 caused 20 fatalities, more than 200 injuries, and over a billion dollars in damage in the Southeast United States. The event occurred concurrently with a record-breaking warm Gulf of Mexico (GoM) basin. This article explores the influence that warm GoM sea surface temperatures (SSTs) had on the tornado outbreak. Backward trajectory analysis, combined with a Lagrangian-based moisture-attribution algorithm, reveals that the tornado outbreak’s moisture predominantly originated from the southeast GoM and the northwest Caribbean Sea. We used the WRF Model to generate a control simulation of the event and explore the response to perturbed SSTs. With the aid of a tornadic storm proxy derived from updraft helicity, we show that the 21–23 January 2017 tornado outbreak exhibits sensitivity to upstream SSTs during the first day of the event. Warmer SSTs across remote moisture sources and adjacent waters increase tornado frequency, in contrast to cooler SSTs, which reduce tornado activity. Upstream SST sensitivity is reduced once convection is ongoing and modifying local moisture and instability availability. Our results highlight the importance of air–sea interactions before airmass advection toward the continental United States. The complex and nonlinear nature of the relationship between upstream SSTs and local precursor environments is also discussed.

TREASURED TRASH: THE SACRED SIGNIFICANCE OF CERAMIC FRAGMENTS IN ELITE RITUAL CONTEXTS AT POSTCLASSIC XALTOCAN, MEXICO

AbstractIn this article, I examine the use of ceramic fragments to mark sacred spaces at the Postclassic central Mexican site of Xaltocan. Recent excavations in Xaltocan's central precinct revealed a series of ritual features dating to Xaltocan's Middle Postclassic period (a.d.1240–1350) that were carefully constructed with ceramic fragments. I argue that this practice might represent an effort on the part of Xaltocan's Postclassic leaders to mark these features as sacred. Although Xaltocan was ruled by Otomi peoples during this time, the careful incorporation of ceramic fragments into ritual spaces might be related to the Nahua concept oftlazolliand possibly reflects the increasing influence of Nahua ideologies across the Basin of Mexico. Despite its generally negative connotations,tlazolliwas a powerful substance that central Mexicans could manipulate to energize ritual spaces. By carefully reordering ceramic fragments in and around ritual features, Xaltocan's leaders might have imbued these spaces with sacred energy. While the concept oftlazollimight have been quite widespread during this time, the specific practices discussed in this article appear to have been isolated to Xaltocan's Middle Postclassic leaders. Perhaps the specific practices observed were an invention of Xaltocan's Middle Postclassic leaders that never spread.

Proyectos y obras para el uso de los terrenos desecados del antiguo lago de Texcoco, 1912-1998

<p>El presente trabajo examina las ideas acerca del posible uso de la tierra descubierta debido a la desecación del lago de Texcoco, producto del Desagüe del Valle de México. El texto explica la variedad de ideas propuestas por ingenieros y otros expertos, muchos de los cuales imaginaron un espacio de múltiples usos, con fines agrícolas, silvícolas, recreativos y ecológicos. La aportación de esta investigación consiste en mostrar cómo y por qué esos planes e ideas cambiaron a lo largo del siglo XX. Los resultados muestran que la transformación de su aspecto y naturaleza ha sido un anhelo constante, limitado por las especiales condiciones del subsuelo. Para la realización de esta investigación se consultó un gran número de fuentes escritas y se acudió al Archivo Histórico y Biblioteca Central del Agua y al Museo Archivo de la Fotografía.</p>

Assessment of nutrient contamination in the waters of the El Fuerte River, southern Gulf of California, Mexico.

This study assessed the spatial and temporal nutrient variability in the El Fuerte River basin in northwestern Mexico, considering its effects on the water trophic status as well as the nutrient loading to the Gulf of California. Physicochemical parameters, inorganic species of nitrogen, phosphate, total nitrogen, total phosphorus, and chlorophyll-a (chl-a) were quantified at 16 selected sites along the river in April (dry season) and October (rainy season) 2017. Mean concentrations of nutrients during dry and rainy seasons were 36.3 ± 24.1 and 55.1 ± 74.6 μg L-1 of total ammonia nitrogen, 3.4 ± 3.6 and 4.5 ± 3.5 μg L-1 of NO2--N, 190.8 ± 256.0 and 163.6 ± 261.0 μg L-1 of NO3--N, 42.4 ± 44.2 and 104.9 ± 76.2 μg L-1 of PO43--P, 1.0 ± 1.3 and 691 ± 2242 mg L-1 of TN, 0.06 ± 0.06 and 0.08 ± 0.09 mg L-1 of TP, and 0.9 ± 0.6 and 2.0 ± 0.9 μg L-1 of chl-a with significant differences (p < 0.05) between sites and seasons. When waters are transported downstream, nutrient levels are enriched by 4 to 35 times compared to those upstream due to increased population and agriculture downstream, confirming the hypothesis of the study. The calculated TN and TP fluxes were 1.23 × 104 and 3.57 × 101 ton year-1, respectively. Factor analysis indicated that inorganic nitrogen species and phosphorus are the main factors affecting the river water quality. Despite N excess during the rainy season, the river reached mesotrophic waters due to phosphorus limitation. This suggests the need to establish a water quality monitoring program to understand the vulnerability of the river course to changes in its trophic state.

Isotopic biomonitoring of anthropic carbon emissions in a megalopolis.

Atmospheric pollution has become a serious threat for human health and the environment. However, the deployment, operation and maintenance of monitoring networks can represent a high cost for local governments. In certain locations, the use of naturally occurring plants for monitoring pollution can be a useful supplement of existing monitoring networks, and even provide information when other types of monitoring are lacking. In this work, we (i) determined the tissue carbon content and the δ13C values for the epiphytic CAM bromeliad Tillandsia recurvata and the relationship of both parameters with the existing CO concentrations in the Valley of Mexico basin and (ii) mapped the spatial distribution of such elemental and isotopic composition for this plant within the basin, in order to assess its potential as an atmospheric biomonitor of carbon monoxide, a pollutant with important repercussions on public health. The CO concentrations in the basin ranged from 0.41 ppm at rural locations to 0.81 ppm at urban sites. The carbon content of T. recurvata, which averaged 42.9 ± 0.34% (dry weight), was not influenced by the surrounding CO concentration. In contrast, the δ13C depended on the sites where the plants were collected. For example, the values were −13.2‰ in rural areas and as low as –17.5‰ in an urban site. Indeed, the isotopic values had a positive linear relationship with the atmospheric CO concentrations. Given the close relationship observed between the isotopic composition of T. recurvata with the CO concentrations in the Valley of Mexico, the δ13C values can be useful for the detection of atmospheric carbonaceous emissions.

El paisaje del agua y la tierra de la Acolhuatlalli a través del mapa de Patlachiuhqui y Moyotepec, Texcoco, 1592

En este artículo se presentan algunos resultados del estudio del mapa pictográfico de de Patlachiuhqui y Moyotepec, Texcoco, ca.1592, que contiene valiosos elementos para reconstruir el paisaje del agua y la tierra de esa porción del Acolhuacan, en el oriente de la Cuenca de México. Interesa en particular la continuidad del uso de dos acueductos que podrían ser los construidos por Nezahualcoyotl en el siglo XV, utilizados con nuevos objetivos. El estudio se basa en el análisis de los espacios, dibujos, glifos y glosas del mapa pictográfico, en la información de los documentos del expediente de procedencia y en otras fuentes históricas.

A novel biodegradation parameter derived from bicyclic sesquiterpanes for assessing moderate levels of petroleum biodegradation

Gas chromatography–mass spectrometry (GC–MS) and Fourier transform ion cyclotron resonance–mass spectrometry (FTICR–MS) analyses were performed on 39 heavy oils from an onshore basin in southeastern Mexico to investigate the influence of biodegradation on whole oil compositions. Among the biodegradation resistant C14–C16 bicyclic sesquiterpanes (bicyclanes), a rearranged C15 isomer (compound X) becomes relatively enriched with increasing biodegradation levels, contrasting with a reduction in the summed C14–C16 bicyclanes concentration but consistent with an enrichment of the bicyclic naphthenic acids revealed by FTICR–MS data. The concentration ratio of compound X over all the identified C15 bicyclane isomers (DMHD ratio) is proposed as a new biodegradation parameter. This ratio correlates well with the biodegradation ratios of 3-methylchrysene/methylchrysenes, benzonaphtho[1,2-d]thiophene/benzonaphtho[2,1-d]thiophene and those based on NSO compounds. Compound X has an additional ethyl group but one less methyl group compared to the drimane structure. A lessening of steric effects through demethylation can explain the refractory nature of compound X, and this forms the basis on which possible origins of compound X are discussed. Extensive biodegradation of the studied oil samples is implied by the alteration of polyaromatic hydrocarbons and NSO compounds. This suggests the relative enrichment of compound X can be used as a new indicator for heavy oil biodegradation at Peters and Moldowan biodegradation level (PM level) 4–5, when hopanes and steranes are still intact. Changes in the distribution patterns of some NSO compound species also suggest PM level 4–5.

NATURAL HISTORY OBSERVATIONS OF AMBYSTOMA ALTAMIRANI AND DRYOPHYTES PLICATUS AT SIERRA DE LAS CRUCES, STATE OF MÉXICO, MEXICO

The streams in the mountains surrounding the Valley of Mexico often contain salamanders and anurans. Knowledge of these species is relatively poor, however. We report observations on predation and reproduction in two species from these streams, Ambystoma altamirani and Dryophytes plicatus.

Early Mesozoic synrift Eagle Mills Formation and coeval siliciclastic sources, sinks, and sediment routing, northern Gulf of Mexico basin

AbstractThe sedimentary architecture and provenance of the early Mesozoic incipient northern Gulf of Mexico basin remains controversial due to both lack of outcrop exposure and sample scarcity across the southern United States with subcrop depths approaching 6 km. The Eagle Mills Formation and coeval deposition across the northern Gulf of Mexico provides both a stratigraphic foundation for some ∼15-km-thick overlying Mesozoic and Cenozoic deposits, and a coeval pre-salt equivalent for southern synrift deposits, in one of the most economically significant hydrocarbon basins in the world. This study presents more than 3200 new detrital zircon U-Pb analyses from sixteen Late Triassic pre-salt, siliciclastic, subcrop well samples, and combines over 14,000 linear kilometers of 2-D multi-channel seismic reflection data, 1511 geophysical well logs, and biostratigraphic data from 2478 wells to construct basin-scale pre-salt isochore and structure maps spanning the northern Gulf of Mexico margin from Florida to the USA-Mexican border.The data show that incipient Gulf of Mexico paleodrainage pathways held individual distinctions between basement sources and tectonic controls in three primary regions across the northern Gulf of Mexico: (1) The western Gulf of Mexico paleodrainage extended from the Central Texas uplift highlands to the submarine Potosi Fan on the western margin of Laurentia with local tributary sources from the East Mexico Arc, Yucatán/Maya, and Marathon-Ouachita provinces as evidenced by inverse Monte Carlo unmixing of peri-Gondwanan (ca. 700–500 Ma), Appalachian/Ouachita (500–280 Ma), Grenville (1250–950 Ma), and Mid-Continent/Granite-Rhyolite Province (1500–1300 Ma) detrital zircon ages. Isochore and associated geophysical well and seismic data suggest that by Early Jurassic time this depocenter had shifted into the present-day western Gulf of Mexico as East Mexico Arc development continued. (2) Southerly drainage in the north-central Gulf of Mexico region bifurcated around the Sabine and Monroe uplifted terranes with southwestern flow characterized by peri-Gondwanan detrital zircon ages from late Paleozoic accreted basement or discrete flexural successor basins, and southeastern fluvial networks distinguished by traditional North American basement province sources including Grenville, Mid-Continent, and Yavapai-Mazatzal. (3) Eastern Gulf of Mexico regional paleodrainage, with regional southern flow dictated by the brittle extensional tectonics of the South Georgia Rift as well as the regional southern flexure of the South Florida Basin, resulted in almost all pre-salt detrital zircon siliciclastic ages from this region to be dominated by local Gondwanan/peri-Gondwanan aged sources including the proximal Suwannee terrane and Osceola Granite complex. These regional, synrift sediment provenance models provide the first critical allochthonous evidence of Late Triassic–Early Jurassic paleodrainage stemming from the Appalachian-Ouachita hinterlands into the incipient northern Gulf of Mexico basin with critical implications for pre-salt hydrocarbon exploration and carbon sequestration reservoir potential.

Regional subsidence at the former Texcoco Lake: numerical modelling and settlements prediction

Abstract. This paper describes the application of an EVP one-dimensional constitutive soil model to analyse regional subsidence. The model was modified assuming that the boundary conditions vary over time, as well as considering the stratification of the subsoil. It adequately simulates the consolidation process caused by the exploitation of the aquifers that underlie the Mexico basin, and is validated at a site in the former Texcoco Lake, some 14 km north of Mexico City, where geotechnical and piezometric information is available together with records of past subsidence. Settlement predictions were carried out for different periods of time, assuming that pore pressure depletion rates at the permeable borders of the compressible strata remain constant over time.

Transition from Late Jurassic rifting to middle Cretaceous dynamic foreland, southwestern U.S. and northwestern Mexico

AbstractSubsidence history and sandstone provenance of the Bisbee basin of southwestern New Mexico, southern Arizona, and northern Sonora, Mexico, demonstrate basin evolution from an array of Late Jurassic–Early Cretaceous rift basins to a partitioned middle Cretaceous retroarc foreland basin. The foreland basin contained persistent depocenters that were inherited from the rift basin array and determined patterns of Albian–early Cenomanian sediment routing. Upper Jurassic and Valanginian–Aptian strata were deposited in three narrow extensional basins, termed the Altar-Cucurpe, Huachuca, and Bootheel basins. Initially rapid Late Jurassic subsidence in the basins slowed in the Early Cretaceous, then increased again from mid-Albian through middle Cenomanian time, marking an episode of foreland subsidence. Sandstone composition and detrital zircon provenance indicate different sediment sources in the three basins and demonstrate their continued persistence as depocenters during Albian foreland basin development. Late Jurassic basins received sediment from a nearby magmatic arc that migrated westward with time. Following a 10–15 m.y. depositional hiatus, an Early Cretaceous continental margin arc supplied sediment to the Altar-Cucurpe basin in Sonora as early as ca. 136 Ma, but local sedimentary and basement sources dominated the Huachuca basin of southern Arizona until catchment extension tapped the arc source at ca. 123 Ma. The Bootheel basin of southwestern New Mexico received sediment only from local basement and recycled sedimentary sources with no contemporary arc source evident. During renewed Albian–Cenomanian subsidence, the arc continued to supply volcanic-lithic sand to the Altar-Cucurpe basin, which by then was the foredeep of the foreland basin. Sandstone of the Bootheel basin is more quartzose than the Altar-Cucurpe basin, but uncommon sandstone beds contain neovolcanic lithic fragments and young zircon grains that were transported to the basin as airborne ash. Latest Albian–early Cenomanian U-Pb tuff ages, detrital zircon maximum depositional ages ranging from ca. 102 Ma to 98 Ma, and ammonite fossils all demonstrate equivalence of middle Cretaceous proximal foreland strata of the U.S.-Mexico border region with distal back-bulge strata of the Cordilleran foreland basin. Marine strata buried a former rift shoulder in southwestern New Mexico during late Albian to earliest Cenomanian time (ca. 105–100 Ma), prior to widespread transgression in central New Mexico (ca. 98 Ma). Lateral stratigraphic continuity across the former rift shoulder likely resulted from regional dynamic subsidence following late Albian collision of the Guerrero composite volcanic terrane with Mexico and emplacement of the Farallon slab beneath the U.S.–Mexico border region. Inferred dynamic subsidence in the foreland of southern Arizona and southwestern New Mexico was likely augmented in Sonora by flexural subsidence adjacent to an incipient thrust load driven by collision of the Guerrero superterrane.

Anisotropy of lacustrine soils in a large oedometer equipped with bender elements

Lacustrine soils from the former Texcoco Lake within the Basin of Mexico, some 14 km north of Mexico City, have unique geotechnical properties. These materials have been thoroughly studied in the past, and yet, very few investigations have addressed the issue of the anisotropy of their shear stiffness modulus at very small strain levels (G0). Stiffness anisotropy, even at very small deformations, may significantly influence the response of the soil in a variety of cases and applications including soil-structure interaction problems under static and dynamic conditions. In this study, a large-size oedometer equipped with bender elements was used to measure the shear wave velocities along different paths as an indirect assessment of G0. The initial or inherent anisotropy of the materials was evaluated with these measurements. The experimental results revealed that the stress-induced anisotropy was not significant; hence, the shear stiffness modulus was seen to depend mainly on the initial anisotropy. An inverse correlation between the yield stress (σ’y) (or over-consolidation ratio, OCR) and the initial anisotropy was found, whereas a direct correlation between the liquidity index and the initial anisotropy was also disclosed.

The relevance of gene flow with wild relatives in understanding the domestication process.

The widespread use of genomic tools has allowed for a deeper understanding of the genetics and the evolutionary dynamics of domestication. Recent studies have suggested that multiple domestications and introgression are more common than previously thought. However, the ability to correctly infer the many aspects of domestication process depends on having an adequate representation of wild relatives. Cultivated maize (Zea mays ssp. mays) is one of the most important crops in the world, with a long and a relatively well-documented history of domestication. The current consensus points towards a single domestication event from teosinte Zea mays ssp. parviglumis from the Balsas Basin in Southwestern Mexico. However, the underlying diversity of teosintes from Z. mays ssp. parviglumis and Zea mays ssp. mexicana was not taken into account in early studies. We used 32 739 single nucleotide polymorphisms (SNPs) obtained from 29 teosinte populations and 43 maize landraces to explore the relationship between wild and cultivated members of Zea. We then inferred the levels of gene flow among teosinte populations and maize, the degree of population structure of Zea mays subspecies, and the potential domestication location of maize. We confirmed a strong geographic structure within Z. mays ssp. parviglumis and documented multiple gene flow events with other members of the genus, including an event between Z. mays ssp. mexicana and maize. Our results suggest that the likely ancestor of maize may have been domesticated in Jalisco or in the southern Pacific Coast and not in the Balsas Basin as previously thought. In this context, different populations of both teosinte subspecies have contributed to modern maize's gene pool. Our results point towards a long period of domestication marked by gene flow with wild relatives, confirming domestication as long and ongoing process.

Apropiación y control de recursos en la expansión urbana. La periferia metropolitana como espacio de disputa entre actores sociales

En este artículo se presenta a los pueblos originarios y sus lógicas de acción como parte del conjunto de actores que configuran e influyen en el proceso de urbanización en la periferia metropolitana del Valle de México. Ellos son quienes han poblado tradicionalmente estos espacios y han utilizado los recursos básicos del territorio para su asentamiento, empleo y subsistencia. Lo anterior les otorgó históricamente cierto margen de autoridad y control sobre dichos recursos, situación que ha ido cambiando e incluso perdiéndose con el tiempo, dados los procesos de poblamiento y transformación de su entorno inmediato, y la consecuente intervención de otros actores, con quienes hoy disputan estos recursos, especialmente el suelo urbanizable y el agua, elementos indispensables para la urbanización.

Climatology and Spatiotemporal Analysis of North Atlantic Rapidly Intensifying Hurricanes (1851–2017)

In recent decades, the scientific ability to project tropical cyclone (TC) intensities and tracks has improved. Hurricanes undergoing the process of rapid intensification (RI) have created new barriers in formulating predictions of TC paths and peak velocities. Current research suggests the warming climate may produce more intense TCs with a higher probability of undergoing RI during their life cycle. The increased likelihood of rapidly intensifying TCs necessitates the development of an RI climatology spanning the current North Atlantic record. A time series count analysis suggests a significant increasing trend of RI events in the Atlantic basin by 29.1% (17%–45%) from the years 1900 to 2017. For the entire basin, the peak frequency occurs in September, followed by August, then October. Gulf of Mexico events tend to occur more regularly over June, July, August, and September, while Atlantic storms peak in August, September, and October. The onset of RI typically begins in the Western Caribbean and Gulf of Mexico, west of 85° W. The lifetime maximum intensity typically occurs in the Gulf of Mexico basin. Density analysis suggests the locations of lifetime maximum intensities (LMIs) in rapidly intensifying TCs are clustered through space. It should be noted that these results are dependent upon the HURDAT record of events. This research is necessary in order to find substantive trends in RI events that may aid future predictions of tropical cyclones; therefore, potentially decreasing the lives lost and the cost of damage that these storms are known to cause.

Liver Recovery and Transplantation From Deceased Donors in the Metropolitan Area of the Valley of Mexico

BackgroundEvaluation of donation and transplantation activity allows for strategic planning. Liver donation and transplantation activity in the Metropolitan Area of the Valley of Mexico (MAVM) has never been published. The aim of this study was to analyze deceased liver donation and transplantation, liver use, and observed-to-expected (O:E) ratio in the MAVM. MethodsInformation from 2014 to 2018 was obtained from the National Center of Transplantation and adjusted per million persons. O:E ratio was analyzed and compared between regions. ResultsFrom all Mexican states, Mexico City (CDMX) had the highest liver donation and transplantation per million persons rates in the country. In contrast, when the MAVM was considered, the region was sixth in liver donation and first in transplantation, although the latter was not statistically different to Nuevo Leon (5.4 vs 4.3; P = .52). Liver use in Mexico State within the MAVM (37.8%) was not different from that of CDMX (15th in the nation, 35.2%, P = .78), while deceased donor liver use in the rest of the state was statistically higher (52.4%, P = .01; third in the nation). O:E ratio was higher in Mexico states outside the MAVM (CDMX 10.1, 2.1 vs 29.4, 26.5; P = .009). ConclusionsAnalysis of deceased donation and transplantation of Mexican states without considering the metropolitan areas is insufficient. To consider CDMX as a region without acknowledging the MAVM leads to an inappropriately small denominator during efficiency analysis.