El ajuste del tiempo de rotación de la tierra en la época prehispánica

The results of this investigation show that the pre-Columbian man discovered that the Earth’s rotation lasted23 hours, 56 minutes and four seconds. In order to registerthis movement, the pre-Columbian man invented theaverage solar day of 24 hours, here the hour had 60 minutesand every minute 60 seconds. In a day, the Earth’s rotationwas ahead to the average solar day by four minutes minusfour seconds, but this difference was of a day less 24 minutesin a year of 360 days. This year, on the other hand, washomologized with a second, so when 60 years had passed,equivalents to 60 seconds (a minute), the Earth’s rotationwas ahead to the average solar day by about 60 days minusa complete day. By such reason, the minute was anotherimportant unit in the computation of the time of Earth’srotation. In this homologation one hour, equivalents to3600 years, this difference amounts to 10 years of 360 days,less two lunations of 30 days each one. In affinity, when thecycle of 24 hours equivalents to 86 400 years was completed,the Earth rotation was ahead of the average solar day by240 years of 360 days, minus four years of 360 days. Inorder to register this movement, the constellations calledMayor Osa and Cassiopeia were used like celestial markersfor a period of time that surpassed 10 000 years from today.Considering the reiterated presence of the used models toadjust the Earth’s time rotation in archaeological sites ofMexico, it is concluded that this was one of the main causesof the pre-Hispanic cultural development.Los resultados de esta investigación muestran que el hombreprecolombino descubrió que la rotación de la Tierra tenía unaduración de 23 horas, 56 minutos y cuatro segundos. Para registrareste movimiento se generó el día solar medio de 24 horas. Cada horatenía 60 minutos y cada minuto 60 segundos. En un día la rotación de latierra se adelantaba al día solar medio cuatro minutos menos cuatrosegundos y esta diferencia ascendía a un día menos 24 minutos en unaño de 360 días. Este año, a su vez, se homologó con un segundo, por loque en 60 años, equivalentes a 60 segundos (un minuto), la rotación dela tierra se adelantaba al día solar medio, 60 días menos un día completo.Por ello, el minuto fue una unidad importante en la computación deltiempo de la rotación de la tierra. En esta homologación una hora equivalea 3600 años, dando una diferencia de 10 años de 360 días, menosdos lunaciones de 30 días cada una. Al completarse 24 horas, equivalentesa 86 400 años, la rotación de la tierra se adelantaba al día solarmedio 240 años de 360 días, menos cuatro años de 360 días. Pararegistrar este movimiento las constelaciones Osa Mayor y Cassiopeiase usaron como marcadores celestes, desde hace más 10 000 años.Dada la presencia reiterada de los modelos utilizados para ajustar eltiempo de la rotación de la tierra, en los sitios arqueológicos de México,se concluye que ésta fue una de las causas principales del desarrollocultural del hombre prehispánico

Selective adsorption of nitrogen compounds using silica-based mesoporous materials as a pretreatment for deep hydrodesulfurization

The adsorption of quinoline (Q) and dibenzothiophene (DBT)—model compounds for nitrogen and sulfur in diesel fuels—over mesoporous SBA-15, SBA-16, and MCM-41 was studied. The Langmuir model was suitable for describing the adsorption of nitrogen-containing compounds from a simulated diesel fuel. A pseudo-second order kinetic model better fitted the Q adsorption data than a first-order rate model when describing the adsorption rates on all materials. Comparison of the adsorption of Q and DBT confirmed that the nitrogen compound was selectively removed, and MCM-41 was found to have better adsorption characteristics than SBA-15 and SBA-16. DBT was not adsorbed in any experiment. The adsorbents were characterized using N2-physisorption, powder X-ray diffraction, and high-resolution transmission electron microscopy to describe the morphologies of the adsorbents. The characterization results revealed that the specific area and the structure of the adsorbent are key parameters required to explain the adsorption process

The Antioxidant Mechanisms Underlying the Aged Garlic Extract- and S-Allylcysteine-Induced Protection

Aged garlic extract (AGE) is an odorless garlic preparation containing S-allylcysteine (SAC) as its most abundant compound. A large number of studies have demonstrated the antioxidant activity of AGE and SAC in both in vivo—in diverse experimental animal models associated to oxidative stress—and in vitro conditions—using several methods to scavenge reactive oxygen species or to induce oxidative damage. Derived from these experiments, the protective effects of AGE and SAC have been associated with the prevention or amelioration of oxidative stress. In this work, we reviewed different antioxidant mechanisms (scavenging of free radicals and prooxidant species, induction of antioxidant enzymes, activation of Nrf2 factor, inhibition of prooxidant enzymes, and chelating effects) involved in the protective actions of AGE and SAC, thereby emphasizing their potential use as therapeutic agents. In addition, we highlight the ability of SAC to activate Nrf2 factor—a master regulator of the cellular redox state. Here, we include original data showing the ability of SAC to activate Nrf2 factor in cerebral cortex. Therefore, we conclude that the therapeutic properties of these molecules comprise cellular and molecular mechanisms at different levels

Effect of Ni on MCM-41 in the Adsorption of Nitrogen and Sulfur Compounds to Obtain Ultra-Low-Sulfur Diesel

Adsorption of heterocyclic sulfur and nitrogen compounds like dibenzothiophene (DBT) and quinoline (Q), respectively, was carried out using mesostructured adsorbent MCM-41 and Ni/MCM-41 in calcined (C) and reduced (R) form. These materials were proved in a batch adsorption system using a model fuel diesel: a mixture of dodecane, DBT and Q with the same concentrations of ppmw of sulfur and nitrogen at 313 K and atmospheric pressure. When MCM-41 was impregnated with Ni, an important modification of the adsorption properties was observed, for example, the uptake of DBT was increased and this adsorption was twice in Ni/MCM-41 in reduce form than in the calcined form. On the other hand, for the nitrogen adsorption of Q diminished by 62 and 58%, considering Ni/MCM-41 in reduce form and in calcined form as adsorbent, respectively. This is a significant achievement regarding the desulfurization and denitrogenation, especially for commercial diesel without pretreatment. Moreover, the kinetic results were adjusted with second order considering Q as nitrogen and DBT as sulfur molecule. Data fitting for Q was achieved better by the Langmuir model for all materials than the Freundlich model, meanwhile the experimental adsorption data of DBT was fitted to the Freundlich model for Ni/MCM-41 calcinated and reduced form

La enseñanza de la Historia: Una mirada desde la práctica docente

El presente trabajo investigativo corresponde a una propuesta de trabajo áulico en la escuela primaria referente a la enseñanza de la Historia con el propósito de desarrollar en los educandos el pensamiento histórico y promover en ellos el desarrollo de las competencias: noción espacio-temporal, empatía histórica y contextualización, interpretación de la Historia a través de la investigación escolar y representación de la Historia, mediante la aplicación de estrategias de enseñanza basadas en el Proyecto Paidós. La metodología empleada por los investigadores fue la investigación acción. El trabajo se realizó en coordinación entre docentes investigadores de la Centenaria y Benemérita Escuela Normal para Profesores y una docente en formación quien realizó sus prácticas profesionales en la primaria Lázaro Cárdenas de Toluca, Estado de México. Los resultados obtenidos permiten concluir en primer lugar que el tiempo asignado a la enseñanza de ésta asignatura según el plan y programas de estudio 2011 de Educación Básica, es muy corto para poder aplicar estrategias que fomenten el pensamiento histórico; asimismo también se concluye que las estrategias aplicadas en el aula permitieron el logro de competencias propias del pensamiento histórico en los educandos de básica, lo cual se valoró mediante la aplicación de cuestionarios y encuestas; finalmente se resalta que la investigación acción como metodología investigativa, permite al docente la reflexión, mejora y transformación de la práctica para impactar en la calidad de la educación que se ofrece en México

Evaluación bacteriana de queso artesanal Zacazonapan madurado bajo condiciones no controladas en dos épocas de producción

Traditional Zacazonapan cheeses have unique organoleptic characteristics and are characterized by being linked to the territory of origin. In the maturation process, there are many interactive variables that are responsible for physical, chemical, biological and structural changes. In order to evaluate the bacteriological evolution of artisanal cheeses during their maturation under non-controlled conditions in two production periods, samples of raw milk and cheese were collected at 0, 30, 60, 120 and 150 d of maturation. The presence of molds and yeasts (MaY), mesophilic aerobic bacteria (MAB), Staphylococcus spp. (Staph), total coliforms (TC), fecal coliforms (FC), Salmonella spp. (Salm) and Listeria spp. (List) was determined. The average microbial load was 9.68, 9.38, 8.55 and 8.10 log10 CFU/g of cheese for MaY, MAB, Staph and TC respectively, as well as 2.68 log10 MPN/g of cheese for FC. Salm was not detected but List was. The microbiological evolution of Zacazonapan matured cheese had counts that exceed the maximum levels of the Official Mexican Standard 243 SSA1 2010.Los quesos tradicionales Zacazonapan tienen características organolépticas únicas y se caracterizan por estar vinculados al territorio de origen. En el proceso de maduración se tienen numerosas variables interactivas que son responsables de los cambios físicos, químicos, biológicos y estructurales. Con el objetivo de evaluar la evolución bacteriológica de quesos artesanales durante su maduración bajo condiciones no controladas en dos épocas de producción, se colectaron muestras de leche cruda y de queso a los 0, 30, 60, 120 y 150 días de maduración. Se determinó la presencia de mohos y levaduras (MyL), bacterias mesófilas aerobias (BMA), Staphylococcus spp. (Staph), coliformes totales (CT), coliformes fecales (CF), Salmonella spp. (Salm) y Listeria spp. (List). La carga microbiana promedio fue 9.68, 9.38, 8.55 y 8.10 log10 UFC/g de queso para MyH, BMA, Staph y CT respectivamente, así como 2.68 log10 NMP/g de queso para CF. No se detectó Salm pero si List. La evolución microbiológica del queso madurado Zacazonapan presentó conteos que superan los niveles máximos de la Norma Oficial Mexicana 243 SSA1 2010

Galaxy downsizing evidenced by hybrid evolutionary tracks

An unified picture of stellar and halo mass build-up as a function of mass is presented. Inferred stellar-dark halo mass relations of galaxies, Ms-Mh, out to z=4 together with average LCDM halo mass aggregation histories (MAHs) are used for inferring average Ms growth histories, the Galaxian Hybrid Evolutionary Tracks (GHETs). The more massive the galaxy, the earlier transited in average from an active regime of Ms growth to a passive one: log(Mtran/Msun)=10.30+0.55z ("population downsizing"), where Mtran is the typical transition stellar mass. This result agrees with independent observational determinations based on the evolution of the galaxy stellar mass function decomposition into blue and red galaxies. The specific star formation rate, SSFR, predicted from the derivative of the GHET is consistent with direct measures of the SSFR for galaxies at different z's. The average GHETs of galaxies smaller than Mtran at z=0 (Ms~10^10.3 Msun) did not reach the quiescent regime, and for them, the lower the mass, the faster the later Ms growth rate ("downsizing in SSFR"). The GHETs allow to predict the transition rate in number density of active to passive population; the predicted values agree with direct estimates of growth rate in number density for the (massive) red population up to z~1. We show that LCDM-based models of disk galaxy evolution are able to reproduce the low-mass side of the Ms-Mh relation at z~0, but at higher z's disagree strongly with the GHETs: models do not reproduce the downsizing in SSFR and the high SSFR of low mass galaxies. (Abridged)Comment: 14 pages, 9 figures. To appear in ApJ. References updated/corrected, minor typos correcte