South Mexico Research Articles

Volatility spillovers among MIST stock markets

<abstract> <p>This paper examines the effects of volatility spillover between MIST stock markets. We used daily data from January 3, 2012, to November 16, 2021, and the test of causality in variance, including structural breaks. First, we observed no structural break for Turkey and Indonesia, but there is a structural break in each South Korean and Mexican stock markets. A structural break is found for Mexico the day, aka "El Betito" was arrested. Likewise, we detected a structural break on the first day of the Covid-19 case for South Korea. We surprisingly observed that Covid-19 did not cause a structural break in these markets during the period analyzed, except in South Korea. GARCH (1, 1) models, including structural breaks, show that all series are temporarily and permanently affected by their own shocks. The causality in variance test reveals that MIST countries have volatility spillover effects on each other. There is bidirectional causality in variance between all markets, except South Korea and Mexico. The Mexican stock market is a volatility transmitter for South Korea, but vice versa. The paper indicates a connection in terms of the financial markets of MIST countries, and they are affected by each other's shocks, according to the study results.</p> </abstract>

Comparison of Insecticide Resistance and Its Enzyme Mechanisms among <i>Aedes aegypti</i> Collected with Three Methods in a Dengue-Endemic City in Southern Mexico

Background: Despite the physical and chemical effort to control Aedes aegypti, the arboviruses transmission in the south of Mexico remains latent. Trying to improve the methods of entomological surveillance routinely used, whether the estimation of resistance to insecticides used for its control, as well as their enzyme mechanisms, were influenced by the phase in which the mosquitoes were collected through three different collection methods was investigated. Materials and Methods: Mosquito collections from the “5 de Febrero” neighborhood in Tapachula, Mexico were obtained by ovitraps, larvitraps, and a CDC backpack aspirator. Insecticide resistance of F1 females was determined by WHO diagnostic doses and resistance ratios (RR50), furthermore, levels of insecticide metabolism enzymes were determined by biochemical assays. Results: Overall, in mosquitoes collected by ovitraps, larvitraps, and CDC backpack aspirator respectively, the low mortalities obtained with the discriminant dose to Malathion (27.57%, 26.97%, and 26.91%), and to Bendiocarb (50.5%, 45.36%, and 54.97%) suggest resistance. However, LC50 for Malathion (0.922, 0.934, and 0.915) and for Bendiocarb (0.112, 0.109, and 0.107); and the low resistance ratios (RR50) for Malathion (3.34, 3.29, and 3.27) and for Bendiocarb (2.15, 2.1, and 2.06) does not suggest resistance. Although a slight numerical variation is observed between the three LC50 values, the overlap observed between their confidence intervals allows us to assume that there were no differences between the three methods. In general, esterases (determined with three substrates), glutathion S-transferases (GST) and cytochromes P450 were statistically higher than those of the susceptible strain; and the three enzyme levels were statistically different among the three collection methods (P < 0.01), being those collected with CDC backpack aspirator with the highest levels. Conclusion: Although using a CDC backpack aspirator demonstrated being the best collection method determining a specific resistance mechanism (as elevation at the enzyme level) in the mosquito adult phase, any collection method is reliable to determine whether a field mosquito population is resistant or susceptible to an insecticide.

Effect Of Additional Lemongrass (Cymbopogon Nardus L.) Powder On Antioxidant Activity And Organoleptic Quality Of Wild Cherry (Muntingia Calabura L.) Leaf Powder Mask

Muntingia calabura L., is also known as Jamaica Cherry,is one of plants in the family Muntingiaceae and a native neotropics plant from south of Mexico to Bolivia. The leave contains rich flavonoid, tannin, triterpenoid, saponin, and polyphenol as antioxidant able to reduce free radical and body healthy. This study utilized lemongrass (Cymybopogon nardus L.) as added fragrance of muntingia’s leave powder face mask. Lemongrass is also beneficial for inhibiting bacterial growth, especially Staphylococcus epidermidis brought by several vectors. The objective of this study was to understand the effect of lemongrass added to antioxidant activity of muntinga’s leave powder face mask and also the organoleptic test for this. The result showed that the treatments of lemongrass added in muntinga’s leave powder mask had significant effect antioxidant activity. In addition, the muntinga’s leave powder mask by lemongrass variation added also had significant difference on sensory quality whether on color, texture, and scent.

Record of Aalenian ammonites and bivalves in Canelas, Durango, western Mexico

Rocks from Middle Jurassic marine environments, dated with fossils are distributed in isolated outcrops and subsurface in the northeast, east and south of Mexico. Their facies vary from shallow marine, littoral, fluvial to evaporitic and carbonate sabkha. Continental facies with arc volcanism, dated with different methods share the same age. The presence of Tmetoceras kirki Westermann, Erycitoides sp. and Bositra buchi (Roemer) in shale and sandstone strata, in open platform facies in western Mexico, are the first report of Aalenian faunas in Mexico.

Potential distribution of Croton guatemalensis : a model with reproductive biology data

Background: The inclusion of information on the phenology of any given species can significantly improve the resulting of potential distribution models. Scientific literature does not provide up-to-date information on the abiotic and biotic factors that determine the distribution of Croton guatemalensis , a species native to communities in south Mexico. For the first time, the potential distribution of C. guatemalensis was determined using a model which includes reproductive biology data.&#x0D; Questions: Which bioclimatic and climatic variables most contribute to the distribution of C. guatemalensis ? Does reproductive biology data contribute significantly to the prediction of the species distribution?&#x0D; Studied species/Mathematical model: Croton guatemalensis / Maximum Entropy Modeling&#x0D; Study area and dates: Chiapas, Mexico, January - December 2020.&#x0D; Methods: The MaxEnt 4.4.4 algorithm was used, incorporating 16 variables, including bioclimatic, climatic and elevation. In addition, a habitat suitability layer was built.&#x0D; Results: The model presented a precision of AUC = 0.964 ± 0.004. Eight variables contributed to explain 86.5 % of the potential distribution of the species. According to their contribution to the model, the most important were the seasonality of precipitation, habitat suitability, elevation and April solar radiation. The species was found in the physiographic regions Central America South Mountain Range Subprovince, Central Depression of Chiapas Discontinuity, and Altos de Chiapas Subprovince.&#x0D; Conclusions: The inclusion reproductive biology data of C. guatemalensis contributed to improve the model. This information allows the development of more effective management and conservation plans by identifying the precise regions in which the species is found.

1210. Recommendations for Screening and Diagnosis of Chagas Disease in the United States

BackgroundOver 300,000 people in the United States are infected with Trypanosoma cruzi, the protozoan parasite that causes Chagas disease (CD). Only about 1% of estimated U.S. cases have been identified, usually through blood donor screening, and most people are unaware they have the infection. Screening is critical for increasing case detection and ensuring patients receive appropriate and timely care, but awareness of CD management strategies among healthcare providers is low. Diagnostic guidelines for CD in the United States are needed to increase provider-directed screening and diagnosis.MethodsScreening recommendations were prepared by the U.S. Chagas Diagnostic Working Group, which consists of clinicians, researchers, and public health experts involved in CD programs. The group agreed on six main questions based on the PICO method (Population, Intervention, Comparison, and Outcome). Subgroups discussed each and proposed initial recommendations, which were then shared and validated within the larger group. The recommendations used the GRADE methodology, assigning two sets of ratings: 1) strength of the recommendation, and 2) quality of the evidence.ResultsThe group recommended screening anyone who was born or lived for >6 months in South America, Central America and Mexico (Figure 1). Recent community-based studies found a prevalence of 1-3.8% in this population. Within this population, having a family member with CD, or having clinical conditions suggestive of CD, including electrocardiographic abnormalities, suggest an elevated risk. Screening women of childbearing age and infants born to seropositive women is important for preventing congenital transmission. Test performance may vary depending on several factors, including whether patients are from South America, Central America or Mexico. Confirmation therefore requires positive results on at least two serological tests based on different antigens or formats, in line with Pan American Health Organization (PAHO) recommendations. Once CD is confirmed, patients should receive an electrocardiogram and echocardiogram to monitor for development of cardiac complications.ConclusionThese CD screening recommendations are meant to be a resource for U.S. healthcare providers to simplify testing of at-risk patients.Disclosures Jen Manne-Goehler, MD, DSc, Regeneron (Individual(s) Involved: Self): Scientific Research Study Investigator Caryn Bern, MD, MPH, UpToDate (Wolters Kluwer) (Other Financial or Material Support, Author Royalties)

Knowledge, attitudes and behaviors of Latinas in cleaning occupations in northern New Jersey: a cross-sectional mixed methods study

BackgroundIn the United States, 88.3% of all 1,163,000 maids and housekeeping cleaners are female, and approximately half of them Latinas. Latinas are understudied and underrepresented in health research, particularly involving chemical exposure in cleaning practices, lack of job training, and inadequate access to personal protective equipment. The purpose of this study is twofold: 1) to examine the knowledge (via training experiences), attitudes and behaviors of a heterogeneous group of Latinas who clean occupationally and 2) to assess their cleaning practices at work and at home.MethodsThis mixed-method study consisted of two phases: 1) three focus groups to explore knowledge (via training experiences), attitudes, and behaviors regarding cleaning practices (N = 15) and 2) a 43-question cross-sectional survey. Focus group audio recordings were analyzed using descriptive and in vivo coding and then coded inductively to explore thematic analysis. Statistical analysis of the survey evaluated means, frequency and percentage for each of the responses.ResultsParticipants (n = 9) were women (mean age = 48.78 and SD = 6.72) from South America (n = 5), Mexico (n = 1), El Salvador (n = 1) and Dominican Republic (n = 2). The mean length of time living in the US was 18.78 years and over half (55.6%) worked in the cleaning industry for 10 or more years.Findings from the three focus groups (n = 15) included that training in cleaning often occurred informally at a very young age at home. Participants reported cleaning in groups where tasks are rotated and/or shared. Most were the primary person cleaning at home, suggesting increased exposure. Gloves and masks were the most frequently used PPE, but use was not consistent. For participants who purchase their own products, driving factors included price, smell and efficacy. Some participants used products supplied or preferred by the employer.ConclusionsLatinas in cleaning occupations face a range of social and health barriers including lack of safety and health training, inadequate PPE and low literacy. To address these issues, the development of an intervention is warranted to provide training and resources for this critical population of essential workers.

Phylogeography and morphometric variation in the Cinnamon Hummingbird complex: Amazilia rutila (Aves: Trochilidae)

BackgroundThe Mesoamerican dominion is a biogeographic area of great interest due to its complex topography and distinctive climatic history. This area has a large diversity of habitats, including tropical deciduous forests, which house a large number of endemic species. Here, we assess phylogeographic pattern, genetic and morphometric variation in the Cinnamon Hummingbird complex Amazilia rutila, which prefers habitats in this region. This resident species is distributed along the Pacific coast from Sinaloa—including the Tres Marías Islands in Mexico to Costa Rica, and from the coastal plain of the Yucatán Peninsula of Mexico south to Belize.MethodsWe obtained genetic data from 85 samples of A. rutila, using 4 different molecular markers (mtDNA: ND2, COI; nDNA: ODC, MUSK) on which we performed analyses of population structure (median-joining network, STRUCTURE, FST, AMOVA), Bayesian and Maximum Likelihood phylogenetic analyses, and divergence time estimates. In order to evaluate the historic suitability of environmental conditions, we constructed projection models using past scenarios (Pleistocene periods), and conducted Bayesian Skyline Plots (BSP) to visualize changes in population sizes over time. To analyze morphometric variation, we took measurements of 5 morphological traits from 210 study skins. We tested for differences between sexes, differences among geographic groups (defined based on genetic results), and used PCA to examine the variation in multivariate space.ResultsUsing mtDNA, we recovered four main geographic groups: the Pacific coast, the Tres Marías Islands, the Chiapas region, and the Yucatán Peninsula together with Central America. These same groups were recovered by the phylogenetic results based on the multilocus dataset. Demography based on BSP results showed constant population size over time throughout the A. rutila complex and within each geographic group. Ecological niche model projections onto past scenarios revealed no drastic changes in suitable conditions, but revealed some possible refuges. Morphometric results showed minor sexual dimorphism in this species and statistically significant differences between geographic groups. The Tres Marías Islands population was the most differentiated, having larger body size than the remaining groups.ConclusionsThe best supported evolutionary hypothesis of diversification within this group corresponds to geographic isolation (limited gene flow), differences in current environmental conditions, and historical habitat fragmentation promoted by past events (Pleistocene refugia). Four well-defined clades comprise the A. rutila complex, and we assess the importance of a taxonomic reevaluation. Our data suggest that both of A. r. graysoni (Tres Marías Islands) and A. r. rutila (Pacific coast) should be considered full species. The other two strongly supported clades are: (a) the Chiapas group (southern Mexico), and (b) the populations from Yucatán Peninsula and Central America. These clades belong to the corallirostris taxon, which needs to be split and properly named.

A taxonomic assessment of Chlorospingus flavopectus phaeocephalus and Chlorospingus semifuscus (Passeriformes: Passerellidae), including the description of a new subspecies.

Chlorospingus flavopectus, a widely distributed member of the New World sparrows and finches (Passerellidae), is among the most variable and complex Neotropical bird species. With up to 28 subspecies that inhabit montane forest from Mexico south to Argentina, it presents a recurring leapfrog pattern, with many genetically differentiated lineages, but even more morphologically distinguishable taxa. Chlorospingus flavopectus phaeocephalus is distributed along the eastern Andean slope (from southern Colombia to northern Peru) and in localized patches along the central and southwestern slopes of the Ecuadorian Andes, in the forest remnants of Chimborazo, El Oro, and adjacent Loja provinces. This allopatric distribution was based on plumage similarities, but no genetic or vocal analysis has tested if these populations share a common ancestry. Here, we compared data for populations of C. f. phaeocephalus, C. semifuscus semifuscus from northwest Ecuador, and C. s. livingstoni from west Colombia, and analyzed them in the context of other Chlorospingus. Our phylogenetic analyses revealed that the putative west Ecuadorian populations of C. f. phaeocephalus are nested within C. semifuscus. They also present diagnostic characters when compared to other populations of C. semifuscus and C. f. phaeocephalus. Based on these results, we recognize the population from El Oro and adjacent Loja Provinces as a new subspecies of C. semifuscus, and the population from Chimborazo Province as a morphological variation of C. s. semifuscus.

Les maïs natifs du nord, centre et sud du Mexique

Les maïs natifs sont le patrimoine bio-culturel des paysans indigènes et métis de tout le pays. Leur culture, du fait des conditions agroécologiques et climatiques spécifiques, est source de processus identitaires intercommunautaires. Le maïs fait partie de la culture alimentaire du paysan mexicain, de son appartenance historique et communautaire ainsi que les valeurs et les symboles partagés qui s’y rattachent. Dans cet article, seront discutées les caractéristiques aliénables et inaliénables du maïs et la vulnérabilité de ce binôme, pour rehausser son importance dans la création de la biodiversité des maïs natifs. Dans le but de reconnaître que tout le territoire national est centre d’origine et de diversification du maïs, un parcours de la diversité des mosaïques agricoles dans le nord, le centre et le sud du pays a été effectué. Finalement, on démontre les risques de concevoir les maïs uniquement comme capital naturel.

Archaeomagnetic evidence of a likely earlier occupation of “El Caracol” lava flow (Zacapu Malpaís, Western Mesoamerica)

A comprehensive archaeomagnetic investigation was carried out on seven ceramic fragments recovered at the "El Caracol" lava flow in the Zacapu Malpaís –Michoacan state, Mexico –. A full set of magnetic-mineralogy experiments (encompassing thermomagnetic curves, hysteresis loops, backfield curves, and isothermal remanent magnetization acquisition measurements) were carried out. The experimental methodology also considers magneto-chemical alteration detection, cooling rate, and remanence anisotropy effects to ensure reliable archaeointensity determinations. Five of the seven ceramic fragments – a pipe (potsherd I), vessel's supports (potsherd II and V), a vessel's wall-fragment (potsherd III), and a pipe's nozzle (potsherd VII) – yielded archaeointensity results within the established acceptance criteria to guarantee quality data. Thermal demagnetization of potsherds I, II, V, and VII shows between two and three magnetization components: one associated with potsherd's fabrication, the second with sample's reheating, and the third one, when present, with a viscous component. For each of the first two components, an intensity value was calculated. Potsherds I, II, III, and VII yielded archaeointensity values between 30 and 40 µT, while potsherd V had a much lower value <20 µT. Although secular variation models do not predict such low intensities, similar values have been reported for the center and south of Mexico. Archaeomagnetic dating was carried out with two regional Paleosecular Variation Curves. The "El Caracol" lava flow is an area with human occupation reported from AD 1200. The results obtained in this work, on the contrary, envision the possibility of an early occupation of the site.

789 HIGH RESOLUTION ESOPHAGEAL MOTILITY: VARIABLE GEOGRAPHIC DISTRIBUTION IN A LARGE MEXICAN COHORT

Abstract High resolution esophageal manometry (HREM) has been in use for about a decade. However, there is no available information regarding geographical or regional differences in diagnostic outcome. Aim Characterize the indications, demographics and diagnostic outcome of HREM in a diverse population of Mexico. Methods Data was collected from four major referral centers representing diverse geographical areas of Mexico: central—Mexico City (two centers, years 2016-2020), south (Veracruz, years 2015-2020) and north (Monterrey, years 2013—2020). All consecutive cases referred for HREM were entered into a data base and analyzed using Chicago 3 classification. Data was evaluated using chi-square to compare frequencies among groups. Results 2,932 patients included: Central n = 877(29.9), North n = 1003(34.2), South n = 1052(35.9). Mean age 47.9(11-93), women 1,795(61.2), men 1,137(38.8). Nationwide, the most common indications for testing were: GERD n = 1677(57.2), followed by dysphagia 587(20), atypical GERD 244(8.3), post-operative GERD 230(7.9), chest pain 114(3.9), and post-operative dysphagia 78(2.8). HREM was normal in 1,468(49.9) patients. Table shows the diagnostic distribution among centers: Central-Mexico had more abnormal cases 531(60.5) (p &amp;lt; 0.0.001) vs 407(40.6) North and 532(50.6) South. Achalasia was more commonly diagnosed in the South n = 104(19.5) whereas outlet obstruction 39(967) p &amp;lt; 0.001 and spastic disorders were more common in the North 47(11.8) p = 0.002. Weak peristaltic disorders were more common in Central-Mexico 369(78.8) p &amp;lt; 0.001. Conclusion This study represents the first large comparative multicenter HREM data base project in Mexico. In this cohort, most patients receiving HREM are women and those whose indication was GERD. These findings indicate variable regional geographical distribution of HERM diagnosis. Our study suggests that further investigation into the causes and epidemiological distribution of motility disorders is warranted.

Identification of small open reading frames (sORFs) associated with heat tolerance in nitrogen-fixing root nodules of Phaseolus vulgaris wild-type and cv BAT93

Common bean is an important legume crop and a major source of protein for low-income groups around the world. Legumes have the ability to engage symbiotic interactions with nitrogen-fixing soil bacteria. In this study, next-generation sequencing technology was used to perform transcriptome analyses of a yet unexplored group of peptides encoded by small open reading frames (sORFs; &lt; 150 codons) in nitrogen-fixing symbiotic nodules of two heat-tolerant genotypes of common bean (Phaseolus vulgaris L): the cultivar BAT93 and a wild genotype (named P. vulgaris 7) from the south of Mexico. After heat stress, total RNA was isolated and used for transcriptome analysis. Sixty differentially expressed sORFs were identified between control and heat stress treatments. The expression profiles of these sORFs suggest that, regardless the evolutionary closeness between P. vulgaris BAT93 and P. vulgaris 7, each genotype has independently adapted their molecular signaling pathways to survive heat stress. The dataset developed may provide a useful resource for future genetic and genomic studies in these species

How well do atmospheric reanalyses reproduce observed winds in coastal regions of Mexico?

AbstractAtmospheric reanalyses are widely used for understanding the past and present climate. They have become increasingly used within the renewable energy sector for assessing wind and solar resources for different regions of the globe in conjunction with observations. Mexico is a country with considerable potential for wind energy production, especially around coastal sites and therefore the characterization of wind resource in these areas of the country is imperative for the most beneficial use of these resources. In this study, we assess how well three global reanalyses, namely ERA‐Interim, ERA5 and MERRA‐2, can reproduce wind observations at a number of key sites across the country. We find that the reanalyses' ability to reproduce these observations is highly variable between different regions in Mexico. Correlation coefficients are around 0.9 in the south of the country where the winds are strongest, but much lower (around 0.5) in Baja California Sur due to the complex coastal topography of the region. ERA5 outperforms ERA‐Interim and MERRA‐2 consistently across the vast majority of sites and so this reanalysis is recommended for local wind power studies. The consistently improved performance compared with ERA‐Interim shows the value of the increased spatial resolution of ERA5. However, in the south and east of Mexico, despite having the highest correlations, ERA5 also has the largest bias, meaning that it underestimates winds consistently across most of the country. Poor correlations between ERA5 and the observations in Veracruz are considered as a case study to understand potential drivers of low wind biases.

Calling phenology of anurans in a tropical rainforest in South Mexico: testing predictive models

ABSTRACT Anuran calling activity has been widely associated with abiotic factors, such as temperature, rain and photoperiod. In this sense, mathematical modelling could help us to decipher the mechanisms that underlie these phenomena in order to be able to predict possible scenarios. Here, we propose 15 models that incorporate some environmental variables with biologic relevance: photoperiod, accumulated rain, dry/wet season, and annual mean temperature. The calling activity patterns were obtained with an automated recording system (ARS) for 7 months in Nahá, Chiapas, Mexico, where nine species were recorded. Those models were compared through the Akaike information criterion corrected for small samples (AICC ) to find the one that best fits. Our results point to a sinusoidal model containing photoperiod, dry-wet season and accumulated rain as the best model. Photoperiod resulted as a critical variable driving phenological calling activity patterns since whenever it was incorporated in a model, its values were reduced. It is interesting because the photoperiod, through photoreception, allows anurans to synchronise their physiology and behaviour throughout the year, being able to control the growth, development and maintenance of organisms by starting the reproduction phases in optimal seasons for their development. However, it is also important to highlight that phenological structure of the anuran calls in Nahá, México is better explained by a combination of mechanisms, which includes photoperiod, rainfall and seasonality, but not temperature.

Population expansion and genetic structure in Cephalocereus nizandensis (Cactaceae), a microendemic cactus of rocky outcrops of the Tehuantepec basin, Mexico

Background and aims – Cephalocereus nizandensis is a microendemic columnar cactus that grows isolated in xerophytic enclaves associated with rocky outcrops in the Isthmus of Tehuantepec, in the south of Mexico. Its demographic history and genetic structure were assessed to determine the main events that shaped its current restricted distribution.Material and methods – Chloroplast intergenic sequences of 40 individuals and inter simple sequence repeats (ISSRs) of 45 individuals from four isolated populations were used to estimate haplotypic and nucleotide diversity, using expected heterozygosity and the Shannon index. AMOVA, population pair-wise FST, and Bayesian clustering analyses were performed to explore the genetic structure. Demographic history was estimated with neutrality tests, mismatch distribution analysis, and Bayesian skyline plots. Phylogenetic relationships and divergence times were determined using a median joining network and a Bayesian molecular clock.Key results – C. nizandensis has a high diversity and moderate genetic differentiation. The lowest elevation locality was found to be the most genetically distinct. The species has undergone a process of population expansion that began 150,000 years ago and has remained without evidence of a population contraction in the transition from the Pleistocene to the Holocene (11,700 years ago).Conclusions – C. nizandensis presents moderate but significant genetic differentiation, which may be due to an early divergence of its populations. Currently observed levels of genetic diversity are the result of historical maintenance of high population sizes and a population expansion approximately in the last 150,000 years, which was sustained independently of the climatic fluctuations of the Early Quaternary, due in part to the stability of the rocky habitat.

Weltrichia magna sp. nov., a new record for the Middle Jurassic of Oaxaca, México

The Jurassic locality San Juan Mixtepec (Zorrillo Formation in the state of Oaxaca) contains fossil plants of the order Bennettitales, mainly of the genus Zamites, as well as reproductive structures of the genera Williamsonia, Williamsoniella and Weltrichia, but male reproductive structures of the latter genus are scarce and almost restricted to the south of Mexico; they have also been reported in the Triassic of the north of Mexico. Here we report a new record for this locality and a new species of male reproductive structure of the genus Weltrichia. We recovered half of an adpression in fine-grained sandstone with the positive and negative of the adaxial part of the male reproductive structure, which when open measures 22.6 cm in diameter. A reconstruction suggests the presence of ten centrifugal rays that become thinner towards the acute apex and are fused in a central basal cup. The structure exhibits complete centrifugal rays with basal structures that are interpreted as insertion sites for pollen sacs. We employed acetate peel, mechanical separation and hydrofluoric acid (HF) maceration techniques for extraction of anatomical samples. We compared 13 morphological and 10 anatomical characters with previous records from localities in México, Europe, Asia and other parts of the world. We observed epidermal cells and syndetocheilic stomatal apparatuses, which corroborate an epidermal affinity to the Bennettitales. This new record would be the largest male reproductive structure found in the region thus far, and increases the distribution of Weltrichia in the Jurassic of Oaxaca.

LAPEN Symposium: Active Learning of Physics in Latin America

This symposium proposed by the Latin American Physics Education Network (LAPEN) is devoted to show some results on Physics Education research for high school and university level carried out in the Latin-American region. We focus in the Active Learning of Physics methodologies. There are three contributions from Ecuador, Colombia and Mexico: The topics studied are: (1) The teaching of Special Relativity Theory with Peer Instruction, developed in the Escuela Superior Politécnica del Litoral in Guayaquil, Ecuador. (2) Active Learning of Electromagnetism for engineering students, developed in the University Antonio Nariño in Bogota, Colombia. (3) Rasch Analysis and Active Learning of electrical circuits for high school students, developed at the COBAY school Xoclán Plantel, in Mérida Yucatán in the south of Mexico The Active Learning methodologies are important because there are good results in the literature about their implementation in different educational levels. Besides, it is a way to innovate the physics class, unfortunately in the Latin America region their effectiveness has been little studied. This brief report sheds more light on the matter.

Monthly fluctuation of colony size and composition of the free-tailed bat Tadarida brasiliensis in the southernmost roost of Mexico

The free-tailed bat (Tadarida brasiliensis) likely migrates from the southwestern USA and northern Mexico to the south of Mexico to spend the winter in the Cueva San Francisco (CSF), which is the southernmost known roost of the species. In this study, we examined colony size and composition of the free-tailed bats at the CSF for two annual cycles to know if these parameters fluctuate throughout the year and whether these fluctuations indicate that the CSF is a winter roost. From February 2018 to November 2019, we conducted monthly observations and captured bats with a mist net of 12 × 2.6 m to determine sex, age, reproductive status, and relative abundance. The duration of the emergence flight (DEF) was also recorded. We detected significant fluctuations in colony size that were caused by the movement of pregnant females in spring, lactating and post-lactating females and males in summer, and by females and males in autumn and winter. The CSF was occupied all year-round by females and males. Our results indicate that the cave is a winter roost for females and males, a transitional roost for pregnant females that form their maternity colony elsewhere in summer, and a temporary roost for males in summer. We suggest that the CSF is crucial for the conservation of the free-tailed bat.

Features of patients that died for COVID-19 in a hospital in the south of Mexico: A observational cohort study.

Due to the wide spread of SARS-CoV2 around the world, the risk of death in individuals with metabolic comorbidities has dangerously increased. Mexico has a high number of infected individuals and deaths by COVID-19 as well as an important burden of metabolic diseases; nevertheless, reports about features of Mexican individuals with COVID-19 are scarce. The aim of this study was to evaluate demographic features, clinical characteristics and the pharmacological treatment of individuals who died by COVID-19 in the south of Mexico. We performed an observational study including the information of 185 deceased individuals with confirmed diagnoses of COVID-19. Data were retrieved from medical records. Categorical data were expressed as proportions (%) and numerical data were expressed as mean ± standard deviation. Comorbidities and overlapping symptoms were plotted as Venn diagrams. Drug clusters were plotted as dendrograms. The mean age was 59.53 years. There was a male predominance (60.1%). The mean hospital stay was 4.75 ± 4.43 days. The most frequent symptoms were dyspnea (88.77%), fever (71.42%) and dry cough (64.28%). Present comorbidities included diabetes (60.63%), hypertension (59.57%) and obesity (43.61%). The main drugs used for treating COVID-19 were azithromycin (60.6%), hydroxychloroquine (53.0%) and oseltamivir (27.3%). Mexican individuals who died of COVID-19 had shorter hospital stays, higher frequency of shortness of breath, and higher prevalence of diabetes than individuals from other countries. Also, there was a high frequency of off-label use of drugs for their treatment.