Bivariate Analysis of Pollutants Monthly Maxima in Mexico City Using Extreme Value Distributions and Copula

In the present work, we are interested in studying the joint distributions of pairs of the monthly maxima of the pollutants used by the environmental authorities in Mexico City to classify the air quality in the metropolitan area. In order to obtain the joint distributions a copula will be considered. Since we are analyzing the monthly maxima, the extreme value distributions of Weibull and Fréchet are taken into account. Using these two distributions as marginal distributions in the copula a Bayesian inference was made in order to estimate the parameters of both distributions and also the association parameters appearing in the copula model. The pollutants taken into account are ozone, nitrogen dioxide, sulphur dioxide, carbon monoxide, and particulate matter with diameters smaller than 10 and 2.5 microns obtained from the Mexico City monitoring network. The estimation was performed by taking samples of the parameters generated through a Markov chain Monte Carlo algorithm implemented using the software OpenBugs. Once the algorithm is implemented it is applied to the pairs of pollutants where one of the coordinates of the pair is ozone and the other varies on the set of the remaining pollutants. Depending on the pollutant and the region where they were collected, different results were obtained. Hence, in some cases we have that the best model is that where we have a Fréchet distribution as the marginal distribution for the measurements of both pollutants and in others the most suitable model is the one assuming a Fréchet for ozone and a Weibull for the other pollutant. Results show that, in the present case, the estimated association parameter is a good representation to the correlation parameters between the pair of pollutants analyzed. Additionally, it is a straightforward task to obtain these correlation parameters from the corresponding association parameters.

Gravity anomalies determined from mean sea surface model data over the Gulf of Mexico

With the improvements in the density and quality of satellite altimetry data,a high-precision and high-resolution mean sea surface model containing abundant information regarding a marine gravity field can be calculated from long-time series multi-satellite altimeter data.Therefore,in this study,a method was proposed for determining marine gravity anomalies from a mean sea surface model.Taking the Gulf of Mexico(15°–32°N,80°–100°W)as the study area and using a removal-recovery method,the residual gridded deflections of the vertical(DOVs)are calculated by combining the mean sea surface,mean dynamic topography,and XGM2019e_2159 geoid,and then using the inverse Vening-Meinesz method to determine the residual marine gravity anomalies from the residual gridded DOVs.Finally,residual gravity anomalies are added to the XGM2019e_2159 gravity anomalies to derive marine gravity anomaly models.In this study,the marine gravity anomalies were estimated with mean sea surface models CNES_CLS15MSS,DTU21MSS,and SDUST2020MSS and the mean dynamic topography models CNES_CLS18MDT and DTU22MDT.The accuracy of the marine gravity anomalies derived by the mean sea surface model was assessed based on ship-borne gravity data.The results show that the difference between the gravity anomalies derived by DTU21MSS and CNES_CLS18MDT and those of the ship-borne gravity data is optimal.With an increase in the distance from the coast,the difference between the gravity anomalies derived by mean sea surface models and ship-borne gravity data gradually decreases.The accuracy of the difference between the gravity anomalies derived by mean sea surface models and those from ship-borne gravity data are optimal at a depth of 3–4 km.The accuracy of the gravity anomalies derived by the mean sea surface model is high.

Air Quality Estimation Using Nonhomogeneous Markov Chains: A Case Study Comparing Two Rules Applied to Mexico City Data

A nonhomogeneous Markov chain is applied to the study of the air quality classification in Mexico City when the so-called criterion pollutants are used. We consider the indices associated with air quality using two regulations where different ways of classification are taken into account. Parameters of the model are the initial and transition probabilities of the chain. They are estimated under the Bayesian point of view through samples generated directly from the corresponding posterior distributions. Using the estimated parameters, the probability of having an air quality index in a given hour of the day is obtained.

2023‘Happy Chinese New Year'Series of Activities in Mexico: ‘Bicycle Zodiac Decoration Competition'

"Bicycle Zodiac Decoration Competition"is a Mexican local brand under the framework of the global brand"Happy Chinese New Year",It was first established in Mexico City in 2017 and has been successfully held in Mexico City for 6 times.

基于BDWT的运动目标识别及Mexico小波核mean shift跟踪算法(英文)

提出了一种应用于智能交通监控系统的运动目标识别和跟踪方法。针对帧间差分提取运动目标的缺陷与不足,提出了一种基于二进小波变换的运动目标识别算法,即直接在二进小波变换域提取运动区域,从而检测出运动目标。对于检测出来的运动目标,对mean-shift跟踪算法进行了改进,采用以Mexico小波核函数自适应mean-shift算法对目标进行跟踪。实验结果表明,提出的算法可以有效地提取运动目标,即使目标与背景具有较高的相似度,也可以较准确的提取出前景运动信息,效果要好于传统的帧差法;跟踪目标准确度高,不受目标大小变化的影响。本算法具较高的实用价值和应用前景。

Mexico草帽小波与电离层CT反演

电离层ＣＴ技术中由于数据采集系统的几何结构存在局限性，致使探测所得数据不完全，导致其成为不完全数据重建问题（有限角度层析）。投影中的采样点不均匀，且由投影谱通过Ｆｏｕｒｉｅｒ中心切片原理组合而得的二维谱平面不完全可知，若要用变换方法重建成象，需要对其进行估计。可以利用小波外推方法估值，但是小波函数的选择具有多样性，文中选用比较常用的Ｍｅｘｉｃｏ 草帽小波进行外推。给出了必要的推导过程和数值模拟结果。

Legal Issues and Scientific Constraints in the Environmental Assessment of the Deepwater Horizon Oil Spill in Mexico Exclusive Economic Zone (EEZ) in the Gulf of Mexico

The largest accidental marine oil spill (4.9 million barrels) in the Gulf of Mexico (GoM) seabed (1600 m) caused by the sinking of the Deepwater Horizon oil rig in 2010, put to the test once again the resilient capacity of the pelagic and benthic realms of this Large Marine Ecosystem. Many are the ecological services provided by its waters (fisheries, tourism, aquaculture and fossil fuel reserves) to neighboring countries (US, Mexico and Cuba). However, the unprecedented volumes of hydrocarbons, gas and chemical dispersants (Corexit) introduced in the system, represent ecological stressors whose deleterious effects are still the subject of civil claims and scientific controversy. Presumably, the short scale effects were confined to the Gulf’s northeastern shallow waters, and the combined actions of weathering, biodegradation, and oil recovery left the system almost under pre-spill conditions. Unfortunately, surface and subsurface oil plumes were detected in the spill aftermath, and their dispersion trajectories threatened Mexico EEZ. Surface oil slicks were detected in the pristine waters of northern Yucatán, while subsurface oil plumes from the Macondo’s well blowout were dangerously advancing southwest towards key fishing grounds in the northwestern GoM. This disaster prompted the Mexican government to implement an ambitious ocean monitoring program adopting a bottom-up approach focused on building a base line for more than 42 physicochemical and biological variables for water, sediment and biota from the continental shelf-slope region of the NW GoM. Technological constraints have precluded systematic observations in the vast Mexican EEZ that could discriminate natural variability and oil seep emissions from antropic disturbances. Therefore, preliminary risk analyses relied on seasonal and historical records. Two years of field observations revealed subtle environmental changes in the studied area attributed to antropic disturbances. Waters maintained oligotrophic conditions and zooplankton and benthic infaunal biomass were also poor. Biomarkers in sediments and biota did not exceed EPA’s benchmarks, and sediment’s fingerprinting (δ13C) indicated marine carbon sources. Geomarkers revealed an active transport from the Mississippi towards the NW GoM of phyllosilicates bearing a weathered oil coating. Consequently, shelf and slope sediment toxicity begins to show an increasing trend in the region. The complexity of hydrocarbons bioaccumulation and biodegradation processes in deep waters of the GoM seems to indicate that meso-and large-scale observations may prove to be essential in understanding the capacity of the GoM to recover its ecological stability.

Comparison of TRMM and Water District Rain Rates over New Mexico

This paper compares monthly and seasonal rain rates derived from the Version 5 （V5） and Version 6 （V6） TRMM Precipitation Radar （TPR, TSDIS reference 2A25）, TRMM Microwave Imager （TMI, 2A12）, TRMM Combined Instrument （TCI, 2B31）, TRMM calibrated IR rain estimates （3B42） and TRMM merged gauge and satellite analysis （3B43） algorithms over New Mexico （NM） with rain gauge analyses provided by the New Mexico water districts （WD）. The average rain rates over the NM region for 1998- 2002 are 0.91 mm d^-1 for WD and 0.75, 1.38, 1.49, 1.27, and 1.07 mm d^-1 for V5 3B43, 3B42, TMI, PR and TCA; and 0.74, 1.38, 0.87 and 0.97 mm d^-1 for V6 3B43, TMI, TPR and TCA, respectively. Comparison of V5 3B43 with WD rain rates and the daily TRMM mission index （TPR and TMI） suggests that the low bias of V5 3B43 for the wet months （summer to early fall） may be due to the non-inclusion of some rain events in the operational gauge analyses that. are used in the production of V5 3B43. Correlation analyses show that the WD rain rates vary in phase, with higher correlation between neighboring WDs. High temporal correlations （〉0.8） exist between WD and the combined algorithms （3B42, 3B43 and TCA for both V5 and V6） while satellite instrument algorithms （PR, TMI and TCI） are correlated best among themselves at the monthly scale. Paired t-tests of the monthly time series show that V5 3B42 and TMI are statistically different from the WD rain rates while no significant difference exists between WD and the other products. The agreements between the TRMM satellite and WD gauge estimates are best for the spring and fall and worst for winter and summer. The reduction in V6 TMI （-7.4%） and TPR （-31%） rain rates （compared to V5） results in better agreement between WD estimates and TMI in winter and TPR during summer.

HBV endemicity in Mexico is associated with HBV genotypes H and G

Hepatitis B virus(HBV)genotypes have distinct genetic and geographic diversity and may be associated with specific clinical characteristics,progression,severity of disease and antiviral response.Herein,we provide an updated overview of the endemicity of HBV genotypes H and G in Mexico.HBV genotype H is predominant among the Mexican population,but not in Central America.Its geographic distribution is related to a typical endemicity among the Mexicans which is characterized by a low hepatitis B surface antigen seroprevalence,apparently due to a rapid resolution of the infection,low viral loads and a high prevalence of occult B infection.During chronic infections,genotype H is detected in mixtures with other HBV genotypes and associated with other co-morbidities,such as obesity,alcoholism and co-infection with hepatitis C virus or human immunodeficiency virus.Hepatocellular carcinoma prevalence is low.Thus,antiviral therapy may differ significantly from the standard guidelines established worldwide.The high prevalence of HBV genotype G in the Americas,especially among the Mexican population,raises new questions regarding its geographic origin that will require further investigation.

National assessment of the fragmentation,accessibility and anthropogenic pressure on the forests in Mexico

Forest managers and policy makers increasingly demand to have access to estimates of forest fragmentation, human accessibility to forest areas and levels of anthropogenic pressure on the remaining forests to integrate them into monitoring systems, management and conservation plans. Forest fragmentation is defined as the breaking up of a forest unit, where the number of patches and the amount of expose edge increase while the amount of core area decreases. Forest fragmentation studies in Mexico have been limited to local or regional levels and have concen- trated only on specific forest types. This paper presents an assessment of the fragmentation of all forest types at the national level, their effective proximity to anthropogenic influences, and the development of an indica- tor of anthropogenic pressure on the forests areas. Broadleaf forests, tropical evergreen forests and tropical dry deciduous forests show the greatest fragmentation. Almost half （47%） of the tropical forests are in close effective proximity to anthropogenic influences and only 12% of their area can be considered isolated from anthropogenic influences. The values for the temperate forests are 23% and 29% respectively. Anthro- pogenic pressure in the immediate vicinity of anthropogenic activities is much higher in the tropical forests （75 in a scale 0-100） than in the tem- perate forests （30）. When considering these results jointly, the tropical forests, and more specifically, the tropical evergreen forests and tropical dry deciduous forests are under the greatest pressure and risks of degra- dation.

National assessment of the evolution of forest fragmentation in Mexico

This paper presents assessments of the fragmentation of the temperate and tropical forests in Mexico at the national level for two dates 1993 and 2002.The study was based on land use and vegetation cover data sets scale 1：250,000.Two broad forest types（Temperate Forests and Tropical Forests） and five more specific forest types（Broadleaf Forests,and Coniferous Forests;Tropical Dry Deciduous Forests,Tropical Sub-evergreen Forests,and Tropical Evergreen Forests） were defined to conduct the analyses.FragStats 3.3 was used to estimate nine metrics of the spatial pattern of the forests for each forest type and date considered.The results indicate that the land cover transitions that have occurred between 1993 and 2002 have resulted in more isolated forest patches with simpler shapes in both the Temperate and Tropical Forests.The remaining Tropical Forest patches have become smaller and more numerous.In contrast,the remaining Temperate Forest patches are fewer and on average larger.Of the more specific forest types defined in this study,the Broadleaf Forests have the highest indicators of fragmentation.However these forests are usually embedded or adjacent to Coniferous Forests.Of more concern for conservation purposes are the high values of fragmentation metrics found for the Tropical Evergreen Forests and Tropical Dry Deciduous Forests,because these forest types are usually surrounded by non-forest land covers or anthropogenic land uses.

Slope Instability on Pyroclastic Deposits: Landslide Distribution and Risk Mapping in Zacapoaxtla, Sierra Norte De Puebla, Mexico

In October 1999, rainfall induced landslides devastated different communities of the Sierra Norte, Puebla, causing more than 250 victims and economic losses greater than $ 450 million. The town of Zacapoaxtla was one of the sectors most affected by slope instability due to the existing geological features and geomorphic characters determined by material properties, landforms and processes. Extensive areas formed by pyroclastic piedmonts developed on the Quaternary volcanic ignimbrite deposits highly dissected by marginal gully erosion combined with an extreme rainfall event played a significant role as an ideal scenario for the occurrence of landsliding. Distribution of landslides triggered by rainfall within the main sector of the Zacapoaxtla municipality was analyzed by using IKONOS images in terms of exploring the likely relationship between mass movement incidence and levels of vegetation density. The later was undertaken by means of producing an NDVI and applying a fragmentation algorithm. Finally, a map of potential areas of mass movements risk was produced based on the combination of a socio-economic vulnerability index, geologic and geomorphological maps and the spatial landslide distribution.

Estimation of rainfall thresholds for shallow landslides in the Sierra Madre Oriental, northeastern Mexico

Landslides induced by prolonged rainfalls are frequent mass movements along the northeastern portion of the Sierra Madre Oriental in Mexico,causing significant damage to infrastructure.In this work,we have studied the connection between rainfall and landslides in the Santa Rosa Canyon,a catchment located in the northeastern Mexico.A landslide database triggered by major storms and hurricanes that have hit the region over the past 30 years was analyzed.A total of 92 rainfall events in the Santa Rosa Canyon were studied to determine the amount of precipitation needed to trigger shallow landslides.For each event the duration(D,in hours)and the cumulated rainfall event(E,in mm)were determined by using historical rainfall data from weather stations located near the study area.We have proposed an ED threshold for rainfall-induced landslides with durations 0.5<D<120 hours to address the conditions that trigger these events in the study area.On analyzing the obtained threshold,it has been established that almost 60 mm of a daily rainfall accumulation is required to trigger shallow landslides in the study area.This estimation is consistent with other calculations made for areas close to the Santa Rosa Canyon.Finally,we validated the predictive capability of the threshold with a different set of rainfall data that did not result in landslides performing a straightforward receiver operating characteristic analysis.A good approach was obtained,especially for rainfall events with daily measurements.Results could be used as input information in the design of a landslide early warning system for the northeastern Mexico,and replicated for other landslide prone areas in the region.

Risk factors for liver disease among adults of Mexican descent in the United States and Mexico

AIM To compare the prevalence of chronic liver disease(CLD) risk factors in a representative sample of MexicanAmericans born in the United States(US) or Mexico, to a sample of adults in Mexico.METHODS Data for Mexican-Americans in the US were obtained from the 1999-2014 National Health and Nutrition Examination Survey(NHANES), which includes persons of Mexican origin living in the US(n = 4274). The NHANES sample was restricted to Mexican-American participants who were 20 years and older, born in the US or Mexico, not pregnant or breastfeeding, and with medical insurance.The data in Mexico were obtained from the 2004-2013 Health Worker Cohort Study in Cuernavaca, Mexico(n =9485). The following known risk factors for liver disease/cancer were evaluated: elevated aminotransferase levels(elevated alanine aminotransferase was defined as > 40 IU/L for males and females; elevated aspartate aminotransferase was defined as > 40 IU/L for males and females), infection with hepatitis B or hepatitis C,metabolic syndrome, high total cholesterol, diabetes,obesity, abdominal obesity, and heavy alcohol use. The main independent variables for this study classified individuals by country of residence(i.e., Mexico vs the US) and place of birth(i.e., US-born vs Mexico-born).Regression analyses were used to investigate CLD risk factors.RESULTS After adjusting for socio-demographic characteristics,Mexican-American males were more likely to be obese,diabetic, heavy/binge drinkers or have abdominal obesity than males in Mexico. The adjusted multivariate results for females also indicate that Mexican-American females were significantly more likely to be obese, diabetic, be heavy/binge drinkers or have abdominal obesity than Mexican females. The prevalence ratios and prevalence differences mirror the multivariate analysis findings for the aforementioned risk factors, showing a greater risk among US-born as compared to Mexico-born MexicanAmericans. CONCLUSION In this study, Mexican-Americans in the US had more risk factors for CLD than their counterparts in Mexico.These findings can be used to design and implement more effective health promotion policies and programs to address the specific factors that put Mexicans at higher risk of developing CLD in both countries.

Power-law Distribution of Normal Fault Displacement and Length and Estimation of Extensional Strain due to Normal Faults:A Case Study of the Sierra de San Miguelito, Mexico

The Sierra de San Miguelito is a relatively uplifted area and is constituted by a large amount of silicic volcanic rocks with ages from middle to late Cenozoic. The normal faults of the Sierra de San Miguelito are Domino-style and nearly parallel. The cumulative length and displacement of the faults obey power-law distribution. The fractal dimension of the fault traces is -1.49. Using the multi-line one-dimensional sampling, the calculated exponent of cumulative fault displacements is -0.66. A cumulative curve combining measurements of all four sections yielded a slope of -0.63. The displacement-length plot shows a non-linear relationship and large dispersion of data. The large dispersion in the plot is mainly due to the fault linkage during faulting. An estimation of extensional strain due to the normal faults is ca. 0.1830. The bed extension strain is always less than or equal to the horizontal extension strain. The deformation in the Sierra de San Miguelito occurred near the surface, producing pervasive faults and many faults are too small to appear in maps and sections at common scales. The stretching produced by small faults reach ca. 33% of the total horizontal elongation.

Using a GIS Tool to Map the Spatial Distribution ofPopulation for 2010 in the State of Mexico, Mexico

The present document describes the experience of using a Geography Information System (GIS) tool to map the spatial distribution of the population of the State of Mexico, Mexico, for 2010. Prior to the development of the experience, dif- ferent projects, tools and products, which offered cartographic representations of the population, were presented, se- lecting one that was developed to function in Idrisi Taiga GIS. Likewise, the GIS tool and the process followed to apply it to a case study in the State of Mexico are described. The result is a raster image that shows the distribution of the population on the analyzed state, offering the possibility to identify the zones where the population concentrates and disperses and to produce an opinion from a geographic point of view on what the origin of these distribution patterns is. Among the conclusions from the analysis of results, distinguishable are the applications that the obtained image can have;for instance, the population can be estimated by basins or risk zones by only adding the values of the cells inside these zones. It is also concluded that the degree of detail expressed by the spatial distribution image of the population will depend on several factors, among them the scale and resolution of the input information and the resolution fixed for the output information.

Development of an Indicator Scheme for the Environment Impact Assessment in the Federal District, Mexico

In this work is developed a proposal of environment indicators needed for the Environment Impact Assessment (EIA) process in Mexico’s Federal District (FD);through which are authorized the construction and realization of different work actions and activities. The methodology is based on the combination of cabinet and field work, performed in three stages. In the first, a documental review was carried out within the topic of Environment Impact (EI), the EIA and the study area, with a subsequent analysis of the environment indicators at an international, national and regional scale. In the second, the systematization of information was performed for the sixteen study cases at a local scale and the organization and analysis of a data base with the allotted information. And in the last stage, a field work was realized with participative observations in three verification sites and interview applications to the principal actors of the EIA process. These results allowed: to determine the main limitations within the EIA process (methodological, technical and operational), to propose an indicators scheme, and to formulate recommendations focused on the improvement of this Environment Public Policy instrument.

Diversity, Distribution and Composition of the Bivalvia Class on the Rocky Intertidal Zone of Marine Priority Region 32, Mexico

The Bivalvia Class, is widely represented in marine ecosystems and is economically important;this research focused on this class and was carried out by sampling the rocky intertidal zone of seven sites located in the Marina Region Priority No. 32, Guerrero, Mexico, where the National Commission for the Knowledge and Use of Biodiversity reported lack of knowledge on marine species living there. The objectives were to examine species richness associated with the rocky intertidal zone, determine how the community is composed by the representation of families based on species richness and abundance, know the distribution of the species, analyze the structure sizes of populations and estimate the diversity index. Sampling was conducted at seven sites;the sampling unit was one square meter and the sampling area was 10 m2. 32 species were identified. Four species are new records for the Mexican Pacific Transitional: one for the state of Guerrero and one for Marine Priority Region 32. Arcidae and Mytilidae Families were better represented in species richness and Chamidae Family was the best represented in abundance. Chama coralloides was considered to be the representative species of the area;Striostrea prismatica showed the greatest size. The diversity index was estimated (H' = 3.65 bits/individuals). Species richness is high and corresponds to that expected in a tropical area.

Spatial-Temporal Analysis of Territorial Transformations in the State of Sinaloa Mexico Using Geographic Information Systems

In the last years the whole planet has been suffering remarkable changes, including the land use and cover, and that this is one of the many components of the global change. The present study has as main objective described the changes of land use and cover occurred in the State of Sinaloa during the period 1976-2011. For this, we used 4 maps of land use and vegetation of 1976, 1993, 2007 and 2011. This analysis was carried out applying statistical techniques and Geographic Information Systems (GIS). The methodology is based on the analysis of the cross-tabulation matrix or change matrix, from which it is possible to obtain indicators of change for each time interval analyzed (1976-1993, 1993-2007 and 2007-2011), as well as the gain and loss of each of the 10 categories contained in the maps. To raise the level of details in the analysis were studied the annual changes considering for this the intensity of the gains and annual losses. Also we elaborated graphs and maps that allow us describing and identifying the magnitude and spatial distribution of the changes. The results obtained show a deterioration in the rainforest, important changes in the irrigated and seasonal agriculture and the spatial exchanges in the forest areas, as well as a considerable increase in the urban areas.

Determination of Optimal Zones for Forest Plantations in the State of Mexico Using Multi-Criteria Spatial Analysis and GIS

This work aims to develop simulation models that allow locating adequate areas for forest plantations in the state of Mexico. It combines multi-criteria evaluation (MCE) techniques and geographic information systems (GIS) to analyze and simulate future scenarios for forest plantations under three major objectives: commercial production, restoration and protection, and agroforestry. Results demonstrate the potential of this method to integrate different variables of social, economic and environmental nature, and for solve some problems of forest activities and management by locating the most suitable areas for this forestal activity.