Freeze-thaw cycles and associated geomorphology in a post-glacial environment:current glacial,paraglacial,periglacial and proglacial scenarios at Pico de Orizaba volcano,Mexico

The glacial history of Pico de Orizaba indicates that during the Last Glacial Maximum,its icecap covered up to~3000 m asl;due to the air temperature increasing,its main glacier has retreated to 5050 m asl.The retraction of the glacier has left behind an intense climatic instability that causes a high frequency of freeze-thaw cycles of great intensity;the resulting geomorphological processes are represented by the fragmentation of the bedrock that occupies the upper parts of the mountain.There is a notable lack of studies regarding the fragmentation and erosion occurring in tropical high mountains,and the associated geomorphological risks;for this reason,as a first stage of future continuous research,this study analyzes the freezing and thawing cycles that occur above 4000 m asl,through continuous monitoring of surface ground temperature.The results allow us to identify and characterize four zones:glacial,paraglacial,periglacial and proglacial.It was found that the paraglacial zone presents an intense drop of temperature,of up to~9℃ in only sixty minutes.The rock fatigue and intense freeze-thaw cycles that occur in this area are responsible for the high rate of rock disintegration and represent the main factor of the constant slope dynamics that occur at the site.This activity decreases,both in frequency and intensity,according to the distance to the glacier,which is where the temperature presents a certain degree of stability,until reaching the proglacial zone,where cycles are almost non-existent,and therefore there is no gelifraction activity.The geomorphological processes have resulted in significant alterations to the mountain slopes,which can have severe consequences in terms of risk and water.

Bedrock outcropping in the accumulation zone of the largest glacier in Mexico(Glaciar Norte of Citlaltépetl),as evidence of a possible accelerated extinction

The highest volcano in Mexico,at the same time the third largest mountain in North America(Citlaltépetl,5610 m a.s.l.),is home to the largest glacier in the country.Because of the extinction of the Popocatépetl glacier(5500 m a.s.l.)caused by eruptive activity,and the almost disappearance of the Iztaccíhuatl glaciers(5220 m a.s.l.)due to the lower elevation of the mountain,the Glaciar Norte of Citlatépetl has been the only glacier that has shown a certain degree of stability as a response to the altitude in which it is located.However,as occurs in almost all glaciers on the planet,the retreat of its glacier terminus has been continuous.Furthermore,during the last years the thickness of its upper part began to decrease rapidly until its bedrock was exposed for the first time in 2019.Due to its ecosystem importance and because it is the main glacier in Mexico,as well as the only one in the world located at latitude 19°N,in this work its current dimensions are updated,as well as the local climatology that governs the current state of the glacier is pointed out.The study was based on the analysis of high-resolution Sentinel-2 optical images,as well as through Sentinel-1 SAR images,with the support of climatological information from the study area.Therefore,the outcropping of the bedrock in the accumulation zone and the consequent horizontal retreat of the upper part of the glacier are documented;at the same time,the decrease in the thickness of the ice along it is noted.The rocky outcrop in the accumulation zone suggests that the flow dynamics of the ice towards the ablation zone will be considerably less,accelerating the retreat of the glacier terminus.Finally,the ascent of the glacial front to 5102 m a.s.l.and the modelled altitude of the equilibrium line to 5276 m a.s.l.are reported as a warning signal in terms of snow catchment and mass balance;likewise,the decrease of 23%of its surface is also indicated regarding the surface reduction monitoring that has been done until 2017.These findings may indicate that the future of this glacier is related to its possible extinction sooner than previously thought,with severe environmental consequences,especially in terms of the provision of drinking water for thousands of inhabitants of the slopes of the volcano.This research is expected to help reflect on the impacts of current climate variability and at the same time serve as a reference for the tropical glaciers on the planet.

Litter buffet:On the use of trash bins by birds in six boreal urban settlements

Unintentional food resources in urban areas(street litter,food leftovers,overflowing trash bins)are dietary components of some urban-exploiter bird species.In this study,we report on 13 bird species in six southern Finnish cities using urban trash bins and describe differences in their activity when provided with food resources(i.e.,bait)in different bin types.We used generalized linear models(GLM)and classification and regression trees(CART)to test for associations between environmental variables and bird activity at the binscapes.Bird activity at the binscapes significantly differed among all cities and among types of bins and was significantly higher after placing bait in all cases.Bins with the largest opening had more activity as opposed to those with smaller openings or lids.Corvids and gulls had the highest activity,with corvids usually being present before the bait was placed and gulls increasing their activity thereafter.These differences show that trash bin foraging is highly malleable and thus susceptible to management preventing its occurrence.Suitable waste management measures could aid in reducing the number of species close to bins and their surroundings,benefiting both bird and human health.

Glacial reconstruction and periglacial dynamics at the end of Late Pleistocene on the surface of Cofre de Perote volcano,México:a climatological retrospective

Despite being within the intertropical region of the planet,the Mexican territory still has glacier-covered mountains.In recent decades,important advances have been made in studies on glaciology and periglacial environment in Mexico both for current and past conditions.However,in spite of Cofre de Perote volcano(4200 m a.s.l.)being a strategically located mountain,it has not yet been studied in regards to the glacial and periglacial processes;in fact,those dynamics have modified the mountain massifs in the past.To complement the series of studies on glacial history in the high mountain environment of México,this study reconstructs the glacial cover and the periglacial environment of the volcano surface during the final stage of the Late Pleistocene based on climatic retrospective and through the identification of geomorphological features.The findings indicate the existence of a large glacier(ice cap)that covered the northern,western,and southern slopes of the mountain;while in the eastern sector there were two small glaciers,one being of cirque type,and the other of valley type.The current temperature conditions prevent the occurrence of permanent ice bodies;at the same time,it was found that the periglacial blockfields of the slopes is a legacy of the climatic conditions that prevailed at the end of Late Pleistocene.

Existence of Supercritical Hopf Bifurcation on a Type-Lorenz System

In this paper, a system of Lorenz-type ordinary differential equations is considered and, under some assumptions about the parameter space, the presence of the supercritical non-degenerate Hopf bifurcation is demonstrated. The technical tool used consists of the Central Manifold theorem, a well-known formula to calculate the Lyapunov coefficient and Hopf’s Theorem. For particular values of the parameters in the parameter space established in the main result of this work, a graph is presented that describes the evolution of the trajectories, obtained by means of numerical simulation.

A Solution for Municipal Solid Waste Treatment

This article describes MSW(Municipal Solid Waste)management with APG(Arc Plasma Gasification)technology.First,a brief description of the process and reactor configurations is presented,listing some advantages and disadvantages.Then,alternatives for producing electrical energy with the residue of synthesis gas are addressed.Finally,this technology is proposed as an alternative to face the significant problem of eliminating MSW on a large scale.

Accuracy of transnasal endoscopy with a disposable esophagoscope compared to conventional endoscopy

AIM: To assess feasibility of unsedated esophagoscopy using a small-caliber disposable transnasal esophagosco-py and to compare its accuracy with standard endoscopy.METHODS: We prospectively included subjects who were referred for upper endoscopy. All subjects un-derwent transnasal endoscopy with E.G. Scan^(TM). The disposable probe has a 3.6 mm gauge and at its distal end there is a 6 mm optical capsule, with a viewing angle of 125°. Patients underwent conventional endos-copy after the completion of E.G. Scan^(TM). We describe the findings detected by the E.G. Scan^(TM) and calculate the diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value and Kappa index for esophageal diagnosis.RESULTS: A total of 96 patients(54 women), mean age of 50.12 years(14 to 79), were evaluated. In all cases we were able to perform esophagoscopy with E.G.Scan^(TM). The average realization time was 5 min. A total of 58 alterations were detected in the esophagus, 49 gastric abnormalities and 13 duodenal abnormalities. We found that for esophageal varices, E.G. Scan^(TM) has sensitivity, specificity and diagnostic accuracy of 95%, 97% and 97%, respectively. Kappa coefficients were 0.32 for hiatal hernia, 0.409 for erosive gastroesopha-geal reflux disease, 0.617 for Barrett's esophagus, and 0.909 for esophageal varices.CONCLUSION: Esophagoscopy with E.G. Scan? is a well-tolerated, fast and safe procedure. It has an ap-propriate diagnostic accuracy for esophageal varices when compared with conventional endoscopy.

Model for end-stage liver disease-Na score or Maddrey discrimination function index, which score is best?

AIM: To compare the ability of model for end-stage liver disease(MELD)-Na and Maddrey discrimination function index(DFI) to predict mortality at 30 and 90 d in patients with alcoholic hepatitis(AH).METHODS: We prospectively assessed 52 patients with AH. Demographic, clinical and laboratory parameters were obtained. MELD-Na and Maddrey DFI were calculated on admission. Short-term mortality was assessed at 30 and 90 d. Receiver operating characteristic curve analysis was performed. RESULTS: Thirty-day and 90-d mortality was 44% and 58%, respectively. In the univariate analysis, sodium levels was associated with mortality at 30 and 90 d(P = 0.001 and P = 0.03). Child stage, encephalopathy, ascites, or types of treatment were not associated with mortality. MELD-Na was the only predictive factor for mortality at 90 d. For 30-d mortality area under the curve(AUC) was 0.763(95%CI: 0.63-0.89) for Maddrey DFI and 0.784 for MELD-Na(95%CI: 0.65-0.91, P = 0.82). For 90-d mortality AUC was 0.685(95%CI: 0.54-0.83) for Maddrey DFI and 0.8710 for MELD-Na(95%CI: 0.76-0.97, P = 0.041). CONCLUSION: AH is associated with high shortterm mortality. Our results show that MELD-Na is a more valuable model than DFI to predict short-term mortality.

Hopf Bifurcation Control in a Lorenz Type System

In this paper Hopf bifurcation control is implemented in order to change the bifurcation from supercritical to subcritical in a differential equations system of Lorenz type. To achieve this purpose: first, a region of parameters is identified where the system has a supercritical Hopf bifurcation;second, a class of non-linear feedback control laws is proposed;finally, it is shown that there are control laws which the disturbed system undergoes subcritical Hopf bifurcation.

Mean platelet volume as a novel predictor of systematic inflammatory response in cirrhotic patients with culturenegative neutrocytic ascites

AIM: To identify a mean platelet volume(MPV) cutoff value which should be able to predict the presence of bacterial infection.METHODS: An observational, analytic, retrospective study. We evaluated medical records of cirrhotic patients who were hospitalized from January 2012 to January 2014 at the Gastroenterology Department of "Hospital General de México Dr. Eduardo Liceaga", we included 51 cirrhotic patients with ascites fluid infection(AFI), and 50 non-infected cirrhotic patients as control group. Receiver operator characteristic curves were used to identify the best cutoff value of several parameters from hematic cytometry, including MPV, to predict the presence of ascites fluid infection.RESULTS: Of the 51 cases with AFI, 48 patients(94.1%) had culture-negative neutrocytic ascites(CNNA), 2(3.9%) had bacterial ascites, and one(2%)had spontaneous bacterial peritonitis. Infected patients had greater count of leucocytes and polymorphonuclear cells, greater levels of MPV and cardiac frequency(P < 0.0001), and lower mean arterial pressure compared with non-infected patients(P = 0.009). Leucocytes, polymorphonuclear count, MPV and cardiac frequency resulted to be good or very good predictive variables of presence of AFI in cirrhotic patients(area under the receiving operating characteristic > 0.80). A cutoff MPV value of 8.3 fl was the best to discriminate between cirrhotic patients with AFI and those without infection. CONCLUSION: Our results support that MPV can be an useful predictor of systemic inflammatory response syndrome in cirrhotic patients with AFI, particularly CNNA.

Effect of the thin cell layer technique in the induction of somatic embryos in Pinus patula Schl. et Cham

Pinus patula is a species commonly used for reforestation in Mexico.However,efficient methods for the mass production seedlings are required.Micropropagation particularly by somatic embryogenesis provides an option for the rapid multiplication of high-quality,genetically improved material.This study induces somatic embryogenesis in this species using the thin cell layer(TCL)technique.Two sources of explants(complete immature embryos;lTCL segments from immature embryos)were evaluated.The efficiency of TCL from longitudinal sections[lTCL]and transverse[tTCL]was evaluated.The results show using thin cell layers from immature embryos cultivated in 16 light/8 dark hours achieves induction of somatic embryos.A higher percentage of embryogenic callus was obtained when tTCL segments were used as an explant source.These results produced somatic embryos from tTCL segments of an immature embryo without germinating the seed,making the process more time efficient.In addition,this technique can be used to generate somatic embryogenesis in forest species that have low germination rates.

Higher cardiovascular risk scores and liver fibrosis risk estimated by biomarkers in patients with metabolic-dysfunction-associated fatty liver disease

BACKGROUND The definition of metabolic-dysfunction-associated fatty liver disease(MAFLD)allows identification of metabolically complicated patients.Fibrosis risk scores are related to cardiovascular risk(CVR)scores and could be useful for the identification of patients at risk of systemic complications.AIM To evaluate the relationship between MAFLD and CVR using the Framingham risk score in a group of Mexican patients.METHODS Cross-sectional,observational and descriptive study carried out in a cohort of 585 volunteers in the state of Veracruz with MAFLD criteria.The risk of liver fibrosis was calculated with aspartate aminotransferase-to-platelet ratio index,nonalcoholic fatty liver disease score and fibrosis-4,as well as with transient hepatic elastography with Fibroscan~?.The CVR was determined by the Framingham system.RESULTS One hundred and twenty-five participants(21.4%)with MAFLD criteria were evaluated,average age 54.4 years,63.2%were women,body mass index 32.3 kg/m~2.The Framingham CVR was high in 43 patients(33.9%).Transient elastography was performed in 55.2%of volunteers;39.1%with high CVR and predominance in advanced fibrosis(F3–F4).The logistic regression analysis showed that liver fibrosis,diabetes and hypertension independently increased CVR.CONCLUSION One of every three patients with MAFLD had a high CVR,and in those with high fibrosis risk,the CVR risk was even greater.

Delaware Method Improvement for the Shell and Tubes Heat Exchanger Design

In this paper the Delaware Method published in 1963 is analyzed and upgraded with using correction factors which take into account the undesirable currents of the mean flow. However, this method presents graphically these correction factors which imply an impediment to fulfill the software calculations. Thus, the equations corresponding to the correction factor equations and a Fortran 77 numerical program were established. This system is given to explore different design alternatives in order to find the optimal solution to each proposed problem. The results of this work was a simple software that can perform calculations with the introduction of parameters depending only on the geometry of the heat exchanger, i.e., geometry, temperature and fluid characteristics eliminating the human errors and increasing the calculations speed and accuracy.

Gastric cancer research in Mexico:A public health priority

This study aimed review studies conducted on Mexican patients diagnosed with gastric cancer and/or diseases associated with its development,in which at least one Mexican institute has participated,and to assess their contributions to the primary and secondary prevention of this disease.A search of the Medline database was conducted using the following keywords:gastric/stomach cancer,Mexico.Studies of the Mexican population were selected in which at least one Mexican Institute had participated and where the findings could support public policy proposals directed towards the primary or secondary prevention of gastric cancer.Of the148 studies found in the Medline database,100 were discarded and 48 were reviewed.According to the analysis presented,these studies were classified as:epidemiology of gastric cancer(5/48);risk factors and protectors relating to gastric cancer(9/48);relationship between Helicobacter pylori and pathologies associated with gastric cancer and the development of the disease(16/48);relationship between the Epstein-Barr virus and pathologies associated with gastric cancer and the development of the disease(3/48);molecular markers for the development of diseases associated with gastric cancer and gastric cancer(15/48).Mexico requires a program for the prevention and control of gastric cancer based on national health indicators.This should be produced by a multidisciplinary committee of experts who can propose actions that are relevant in the current national context.The few studies of gastric cancer conducted on the Mexican population in national institutes highlight the poor connection that currently exists between the scientific community and the health sector in terms of resolving this health issue.Public policies for health research should support projects with findings that can be translated into benefits for the population.This review serves to identify national research groups studying gastric cancer in the Mexican population.

Cryotic climate conditions and their eventual implication in the high-mountain surface of the Nevado de Toluca volcano, Mexico

The state of the cryosphere in tropical regions is of great importance because the temperature around the glaciers, permafrost and snow cover always fluctuates near the melting point. These thermal conditions and their high sensitivity to climate change cause the accelerated disappearance of these elements;therefore, it is important to know the climatic factors that regulate them, as well as the physical characteristics of each cryospheric element. Unlike glaciers, permafrost and snow cover have not been widely studied. In recent decades, the study of the glacial and periglacial environment has been carried out in intertropical mountains. However, despite the altitude of their relief and the frequent occurrence of snowfall in tropical high mountains, the conditions that determine such events have been barely analyzed;and in the case of Mexico, the volume of snowfall and its thickness have not been quantified either, as well as their corresponding duration. Consequently, this work is aimed to analyze the temperature and precipitation conditions that determine the snowfall at the higher part of the Nevado de Toluca volcano;at the same time, the conditions of the cryotic climate and their possible implication on the surface are studied. The analysis of data from 1965 to 2016, using frequency statistics, allowed to realize that snowfall occurs with low intensity, its accumulation being less than 10 cm thick and 10 mm of snow water equivalent, which causes the snowpack to stay only a few weeks on average. At the same time, it was determined that there is a significant increase in the number of freeze-thaw cycles. Therefore, due to the climate conditions and their influence on the mountain surface, it is probable that the bedrock is subject to a greater gelifraction dynamics, and the unconsolidated soil surface increases;the combination of the above could cause a greater geomorphological dynamic over time, particularly due to debris flows, and by water and wind erosion of the surface. This work is intended to serve as a reference for the high mountain environment in the intertropical regions.

Antioxidant,anti-inflammatory and antinociceptive potential of Ternstroemia sylvatica Schltdl.&Cham

Objective: To evaluate the anti-inflammatory, analgesic, antioxidant and acute toxicity of extracts obtained from a successive extraction with solvents of ascending polarity[hexane, hex; chloroform, CHCl3 and ethanol(Et OH)] of Ternstroemia sylvatica Schltdl.& Cham.Methods: The antioxidant potential was evaluated by 2,2 diphenyl-1-picrylhydrazyl, the ferric reducing/antioxidant power assays and by determining the total phenolic content.The anti-inflammatory and antinociceptive effects were evaluated using the in vivo croton oil-induced ear edema, phorbol 12-myristate 13-acetate induced ear edema, carrageenaninduced paw edema, acetic acid-induced writhing and formalin murine models. The acute toxicity was tested using the Lorke's method in mice.Results: The Et OH extract was the most active for the antioxidant potential tests diphenyl-1-picrylhydrazyl(68.70% inhibition), ferric reducing/antioxidant power[(2 431.30 ± 102.10) mmol Fe2+and total polyphenols content(215.80 ± 8.50) meq AG/g]. The anti-inflammatory activity was evaluated by topical application of croton oil(2 mg/ear dose) where the Et OH extract showed the strongest activity compared to the control group(45.13% inhibition), whereas in the phorbol 12-myristate 13-acetate model,at the same dose, the CHCl3 extract showed the highest inhibition(42.88%). In the carrageenan induced edema model, the Et OH extract showed a stronger inhibition compared to indomethacin(56.34% and 50.70% at doses of 250 and 500 mg/kg of extract, respectively) during the first hour. Similarly, the same extract showed the highest analgesic activity(30.60% inhibition) in the acetic acid contortion assay, and in the formalin test it showed a greater effect with respect to the control group in both phases.Conclusions: Our work confirms the value of Ternstroemia sylvatica as an important anti-inflammatory and analgesic plant, whose mechanism seems to be associated to its antioxidant effects, and supports its uses in the Mexican traditional medicine.

墨西哥不同地区临床护理服务资源测量指数的研究

目的本研究旨在以孕产妇死亡率为基础,对相关护理数据和社会背景的因素进行分析,制订临床护理服务资源测量指数。方法采用来源于卫生部、国家统计和地理研究所的数据进行分析,包括:护理覆盖率指数、学士学位及以上护士比例、人类发展指数和人口密度。通过主成分分析法构建墨西哥护理资质指数(Index of Nursing Qualification in Mexico,INQM)。结果INQM与护理覆盖排序指数(The NursingCover-age PrioritisationIndex,NCPI)(0.849,P<0.01)及人口密度排序指数(The Population Density Prioritization in-dex,PDPI)(0.716,P<0.01)相关性均较高。通过主成成分分析提取3个公因子,INQM主要由模型中3个主要成分组成。INQM与孕产妇死亡率之间没有显示有统计学意义的相关关系。结论研究表明,形成INQM的要素可能会对严重的公共卫生问题产生影响,该结果为应用这些指标提供了参考,有助于确定临床护理服务资源测量指数的贡献。

A Geometric Morphometrics Study of Stigma-Anther Polymorphism in the Tropical Distylous <i>Palicourea padifolia</i>(Rubiaceae)

Distyly is a floral polymorphism with long-styled flowers and short-styled flowers. Traditionally, floral traits in distylous species have been studied as a variable composed of several linear measurements. We proposed the use of a geometric morphometric approach to studying flower shape and entire flower design variation (including stigma-anther polymorphism) between morphs in Palicourea padifolia. The geometric morphometric approach allowed us to preserve the integrity of the floral form and to project the floral features on the same scale. Moreover, the visualization of a grid deformation allows us to describe shape differences between morphs as well as to estimate the variance-covariance matrix among floral traits. In this study, we demonstrated that flower shape and entire flower design differed between morphs. Intra- and inter-morph variations in the flower size were observed. The flower size has an effect on the anther position between morphs and among individuals. An association between flower shape and flower size was observed in both morphs. A pattern of floral features co-variation between the morphs was demonstrated in the species. In P. padifolia both morphs seemed to be internally coherent with respect to the developmental processes that produce flower shape variation. Changes in floral traits associated with flower size seemed to be more complex than those in the simple uniform expansion of the floral trait positions analogous between morphs. The observed pattern of co-variation of floral features between morphs suggested that flower base shape would be an additionally ancillary trait linked to the stigma-anther polymorphism in the species.