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Island arc tholeiites of Early Silurian, Late Jurassic and Late Cretaceous ages in the El Fuerte region, northwestern Mexico

Island arc tholeiites of Early Silurian, Late Jurassic and Late Cretaceous ages in the El Fuerte region, northwestern Mexico

Three distinctive igneous suites crop out in the El Fuerte block, northwestern Mexico. The oldest of these suites is the Realito Gabbro, which intrudes the Middle-Upper Ordovician Río Fuerte Formation. This gabbro yielded an Early Silurian U-Pb zircon age of ca. 430 ± 15 Ma. The Topaco Formation is a greenschist facies metamorphosed volcanosedimentary sequence. Basaltic rocks of this unit yielded a Late Jurassic U-Pb zircon age of 155 ± 3.5 Ma (Kimmeridgian). The Guamuchil Formation mainly consists of basaltic flows overprinted by greenschist facies contact metamorphism. A sample of this unit yielded a Late Cretaceous U-Pb zircon age of 73 ± 1.5 Ma (Campanian). Geochemical signatures of the three suites suggest an island arc tholeiitic environment. The Upper Jurassic Cubampo Granite is a peraluminous subalkaline granite. Age coincidence and similarities in rare earth element patterns and trace elements concentrations suggest that a genetic link exists between the Cubampo Granite and the Topaco Formation. In a regional context, the Realito Gabbro is coeval with Silurian rocks of the Acatlán Complex in southern Mexico, although geochemical data indicate they originated in different tectonic settings. In a larger scale, the Realito Gabbro rocks are coeval with rocks located along the Appalachian chain and northwestern South America. Late Jurassic magmatism in the El Fuerte region may be the southern prolongation of the continental magmatic belt of Sonora and southwestern USA. Late Cretaceous magmatism of the Guamuchil Formation may correlate with the Sonora-Sinaloa belt of intrusive and volcanic rocks, which was emplaced after accretion of the Guerrero terrane. The island arc tectonic setting indicated by geochemistry of the Mesozoic suites in the El Fuerte region differs from the continental arc setting of north-central Sonora and southwestern USA, which is probably due to mantle source differences.

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FURTHER REMARKS ON THE ROLE OF PRO-THROMBOLITES IN THE ORIGIN OF COASTAL LAGOONS FOR NORTHWESTERN MEXICO

FURTHER REMARKS ON THE ROLE OF PRO-THROMBOLITES IN THE ORIGIN OF COASTAL LAGOONS FOR NORTHWESTERN MEXICO

Extensive benthic mats formed by filamentous cyanobacte- ria occur in most of the intertidal and subtidal margins of the La Paz lagoon, B.C.S., Mexico (Siqueiros-Beltrones, 2006). These are mostly associated to soft, conglomerated (vertically accreted) mats and to more or less consolidated sediment platforms, which due to their rocky appearance with a greenish covering (Siqueiros- Beltrones, 2008) had been hitherto unnoticed. These may be plat- forms and/or fragments of assorted sizes resembling mudstone, but in all cases they occur as seaward hardground extensions. In the case of lithified structures, their clotted nature indicated that these were thrombolithic in nature (Siqueiros-Beltrones, 2008). Thrombolites have been defined as benthic biosedimentary struc- tures generated by the entrapment, binding, and consolidation of sediments as result of the metabolic activity and growth of mi- croorganisms, particularly cyanobacteria; unlike stromatolites do not show internal lamination (Charpy et al., 1999; Stal, 2000; Shap- iro, 2000). This most closely depicts the process we are currently investigating, inasmuch the platforms initially recorded from La Paz lagoon were described as pro-thrombolites, i.e., non lithified sedimentary structures generated by the growth of cyanophyte mats, i.e. clotted sediments with inclusions of shell fragments, irregularly packed, surrounded by a sheet of active cyanobac- teria (Siqueiros-Beltrones, 2008). Although some lack it because of prolonged exposure or for being covered by other sediments (Siqueiros-Beltrones et al., 2009) many still characteristically show a conspicuous sheet of filamentous cyanobacteria, mainly Micro- coleus chthonoplastes Thuret ex Gomont and Lyngbya aestuarii Liebman ex Gomont. Although other species are common, such as Spirulina sp., Oscillatoria spp., Calothrix, and unicellular forms: Chroococcus sp. and Aphanotece sp. (Siqueiros-Beltrones, 2008),

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Autoimmune type chronic active hepatitis in children  A report of 23 cases at a Hospital in Northwestern Mexico

Autoimmune type chronic active hepatitis in children A report of 23 cases at a Hospital in Northwestern Mexico

Introduction: Autoimmune type chronic active hepa- titis (AI-CAH) is a rare pediatric disorder whose principal characteristics include hepatocellular dys- function and active tissue damage with evolution to cirrhosis in 25–30% of cases. Objective: Our aim was to ascertain the evolution of 23 children with AI-CAH treated between 1978 and 2004 at the Hospital Infan- til del Estado de Sonora in the Sonora State capital of Hermosillo in northern Mexico. Materials and meth- ods: We conducted a retrospective review that includ- ed the following variables: age; sex; personal ante- cedents; signs and symptoms; laboratory and medical office studies; histologic tissue pattern obtained by biopsy; treatment; evolution, and mortality. Results: Thirteen males and 10 females participated in the study; predominant signs were hyporexia, fatigue- hepatomegalia, and icterus. Ten patients presented moderate anemia and six patients, leukopenia and thrombocytopenia. Eighteen patients presented hy- pergammaglobulinemia. Twenty three patients had percutaneous (p.c.) liver biopsy, and we observed the following histologic pattern: rupture of the limiting

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Grain size discrimination between sands of desert and coastal dunes from northwestern Mexico

Grain size discrimination between sands of desert and coastal dunes from northwestern Mexico

desert and coastal dunes based on the textural parameters of the sands. Sixty two sand samples were collected from the slip face and crest of linear and sand sheet dunes from the desert and coastal zone of the Altar Desert, Sonora. Textural parameters were determined by a Laser Particle Size Analyzer (Coulter). Among the four groups of dunes studied, El Pinacate desert dune sands are signifi cantly different from the rest of the dune groups in terms of grain size and skewness. This is due to the selectiveness of the northwesterly winds that concentrates fi ner sizes with longer wind transport from the source (Colorado River delta sediments) to the El Pinacate dune fi elds. In contrast, the grain size distributions for the rest of the dune fi elds are affected by their proximity to the sediment sources, tidal transport, long shore drifts and southwesterly and southeasterly winds. Coastal dune sands are coarser than the desert dune sands. This may be caused by the effect of the tidal currents and local winds of the Colorado River delta sediments that locally carry coarser grains onto the beach and landwards. Bioclasts of the beach sand in Puerto Peñasco also exerts a control in the grain size distribution of the dune sand. The linear discriminant analysis and ANOVA test are useful tools to discriminate between desert and coastal dune sands. Some similarities were detected for the grain size distributions between the Altar Desert sands (Mz=1.34φ – 2.79φ; σ=0.35φ – 1.60φ) and the Kalahari Desert sands (Mz=1.55φ – 2.38φ; σ=0.51φ – 1.52φ) that are probably associated with the sediment source of the sands, dune morphology and wind patterns. Key words: coastal dunes, desert dunes, grain size distribution, Altar Desert, Sonora, Mexico.

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Microarthropod communities related with biological soil crusts in a desert scrub in northwestern Mexico

Microarthropod communities related with biological soil crusts in a desert scrub in northwestern Mexico

Abstract. In arid ecosystems, biological soil crusts closely interact with microarthropod communities. Together, both communities play one of the most important environmental services: decomposition of organic matter. In a desert scrub in the southern Baja California Peninsula of Mexico, microarthropod communities were correlated to biological soil crusts and the way soil properties influence distribution of the microarthropods. Twenty five soil samples were taken from 3 site types: without crusts (10), with crusts (10), and eroded surfaces (5). Microarthropods were extracted; specimens were identified to family level and feeding groups were identified. Of the 4 682 microarthropods within 40 taxa, Prostigmata had the greatest richness. The lack of plant coverage at eroded sites seems to affect micro- environmental conditions, so that no microarthropods were found at these sites and biological soil crusts were simple in structure. Among desert scrub, biological soil crusts were complex in structure, and edaphic properties were more favorable for microarthropods to thrive. Specific dissimilarities in community structure of microarthropods for each microhabitat were related to feeding preferences of each taxa.

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Population structure of the Pacific angel shark (Squatina californica) along the northwestern coast of Mexico based on the mitochondrial DNA control region

Population structure of the Pacific angel shark (Squatina californica) along the northwestern coast of Mexico based on the mitochondrial DNA control region

Our results have implications for the design of manage- ment and conservation policies because they suggest 2 popu- lations or stocks for the Pacific angel shark off northwestern Mexico. The adoption of genetic and evolutionary criteria in the management of natural resources has led to the recogni- tion of management units, which represent functionally inde- pendent populations, or groups of populations, characterized by low levels of gene flow (Moritz 1994). In this sense, we suggest that both populations should be considered as sepa- rate management units. Future stock assessment should be done separately for each population. In Mexico, however, tools for legislation (e.g., NOM-029-PESC) do not account for population or stock structure or population dynamics of shark resources. An inadequate management strategy can cause a stock to collapse or lead to local extirpation with eco- logical and economic consequences (Dulvy and Forrest 2010).

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Protein digestibility of chia seed Salvia Hispanica L

Protein digestibility of chia seed Salvia Hispanica L

Chia seeds (Salvia hispanica L) have been consumed in Mexico since pre-hispanic time, recently this seed has been characterized as an excellent source of omega-3 fatty acid, as well of fiber, a show a good amino acid balance, but information regarding its protein quality is poor. Protein digestibility is a valuable parameter to establish protein quality, which could be classified in: high, intermediate, and low. The protein digestibility is influenced by amino acids composition, anti-physiological elements, fiber, pH, temperature, grinding and soaking. The overall aim of the project was to evaluate the in vitro protein digestibility of chia seed. Analytical study with four samples that received different treatments: toasting, grinding (flour), toasting plus grinding, a soaking in water; one was left without treatment. The proximate compositions were studied only to chia seed without treatment. For all samples, the protein digestibility was evaluated by the pepsin method. The sample of chia seed treated with grinding got a low digestibility score (79.8%). The rest of the samples did not get any digestibility classification. Only the grinding treatment improved the digestibility. The amount of fiber could have influenced the digestibility of the protein. It is necessary to continue studying the digestibility of chia seed in combination with other grains and leguminous, and the recommendations would be to eat the chia in combination to improve its digestibility.

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Subsistence hunting for turtles in northwestern Ecuador

Subsistence hunting for turtles in northwestern Ecuador

The Cayapas-Santiago basin is located in the extreme northwestern region of Ecuador near Colombia (Fig. 1). The lower portions of the rivers occupy the northeast corner of Esmeraldas Province along the Pacific coast. We visited several small communities in July and August of 1986 in rural parroquias of the cantons of Eloy Alfaro (Borbón, La Tola, Maldonado, and Timbiré), and San Lorenzo (Carondelet, Concepción, and Tululbí). Along the Santiago River, we visited Concepción and San José de Tagua, plus Nueva Esperanza and La Boca on the Bogotá River, an affluent of the Santiago River. Ricaurte is at the juncture of the Palabí River and Tululbí River, which is an affluent of the Bogotá River. We visited one village on the Cayapas River, Playa Grande. The two senior authors traveled to the region again in January of 1991 specifically to visit Hacienda La Molinita near the mouth of the Cayapas River, a locality we heard about during the prior trip. The area is covered with humid tropical forest that is mostly secondary, or at least has undergone selective harvesting of the valuable timber trees. In 1986, we visited during the relatively dry time of year in late July and early August. As graphed by Naranjo (1981), this is just at the onset of the less rainy time of year that extends

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Protolith age of the Altar and Carnero complexes and latest Cretaceous–Miocene deformation in the Caborca–Altar region of northwestern Sonora, Mexico

Protolith age of the Altar and Carnero complexes and latest Cretaceous–Miocene deformation in the Caborca–Altar region of northwestern Sonora, Mexico

Most workers consider that deformation and metamorphism of El Batamote belt occurred during northeast-southwest–directed com- pression associated with the Late Cretaceous to Paleogene Laramide orogeny (Damon et al., 1962; Hayama et al., 1984; Jacques-Ayala et al., 1990, 2009; Jacques-Ayala and DeJong, 1996; García y Barragán et al., 1998; Nourse, 2001; Nourse et al., 2007). The structural style resembles that observed in areas of Laramide tectonism throughout northern Sonora, southern Arizona and southwestern New Mexico (Haxel et al., 1984, 2008; Nourse, 1995; González-León et al., 2000, 2017; Iriondo et al., 2005; Clinkscales and Lawton, 2015). The timing of the event in El Batamote belt is only loosely constrained. At least part of the deforma- tion postdates the 72 Ma El Charro volcanic complex, which is folded within the center of the range-scale El Chanate syncline (Jacques-Ayala 1993, 1999; Nourse, 2001). The event was probably largely over by the late Paleocene or early Eocene, as indicated by a biotite K-Ar cooling age of 58 ± 3 Ma from the Altar complex east of Altar (Damon et al., 1962) and extrusion of the postkinematic San Jacinto volcanics at 51 ± 2 Ma (Jacques-Ayala, 1999, 2000). Laramide contraction was fol- lowed in the early Miocene by intrusion of granitoid igneous bodies and exhumation along low-angle normal faults (Nourse, 1995, 2001; Jacques-Ayala, 1999).

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TítuloFútbol profesional americano y perspectiva de género: a propósito de unas supuestas declaraciones del Comisionado de la NFL sobre cuotas de mujeres

TítuloFútbol profesional americano y perspectiva de género: a propósito de unas supuestas declaraciones del Comisionado de la NFL sobre cuotas de mujeres

las agresivas tácticas de reclutamiento de jugadores del entonces entrenador del equipo de baloncesto masculino de la Universidad estatal de Nevada]. Por eso, pensamos que el aldabonazo que supone la doctrina del caso Northwestern University, con independencia de que su doctrina acabe o no revocándose, podría llegar a convertirse en la oportunidad y el punto de inflexión que muchos (y sobre todo, muchas) estaban esperando para obligar a repensar (quizá a instancia de las propias autoridades deportivas universitarias, que algo tendrán que hacer, además de recurrir el caso) la citada política federal de fomento del deporte escolar y universitario femenino, la cual ha cumplido con creces su objetivo de lograr la paridad de género a nivel de grandes números (en consecuencia, igualdad formal), aunque sea claro su fracaso en lo tocante al logro de la igualdad real de hombres y mujeres deportistas-estudiantes 48 . Como en una encrucijada, es evidente que podrían teóricamente

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MWM_La Educ@ción

MWM_La Educ@ción

A  largo  plazo,  la  educación  científica,  comenzando  en  los  niveles  básico  y  pre‐universitario,  definirá si el esfuerzo en ciencia fructifica o no. El Proyecto Módulos El Mundo de los Materiales  (MWM,  por  sus  siglas  en  inglés)  conforma  uno  de  los  principales  programas  de  educación  científica  patrocinados  por  la  Fundación  Nacional  para  la  Ciencia  (NSF).  El  programa  MWM  ha  sido creado en Northwestern University (NU) por un grupo multidisciplinario dirigido por el Prof.  RPH Chang. El  proyecto  nació  en  el año 1994,  cuando  se recibió  el  apoyo  inicial por parte de la  NSF.  Se  trata  de  un  sistema  modular  orientado  a  enseñanza  pre‐universitaria.  Se  aplica  en  planteles de prácticamente todos los estados de la Unión Americana y ha probado en la práctica  conducir  a incrementos  significativos  en  el  aprovechamiento  y  la  motivación  de  los  estudiantes  en  relación  con  materias  de  ciencias  naturales  y  matemáticas.  (Ver  la  sección  “Assessing  Learning” en la página web del Programa MWM)

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Preliminary Report on a Late Cretaceous
				Vertebrate Fossil Assemblage in Northwestern Coahuila, Mexico

Preliminary Report on a Late Cretaceous Vertebrate Fossil Assemblage in Northwestern Coahuila, Mexico

Sedimentology and depositional environment of the studied area confirm the presence of the habitat types postulated for the assemblage, or, at least are not contradictory. The freshwater system was situated on a coastal plain which drained in the Palaeogulf of Mexico. Further survey will yield more material for a detailed reconstruction of the local habitat types represented in the area, as well as the entire extent of the system within the paleogeographical context of that time period.

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Composición espacial y temporal de la avifauna de humedales pequeños costeros y hábitat adyacentes en el noroeste de Baja California, MéxicoSpatial and temporal composition of the avifauna from small coastal wetlands and adjacent habitats in northwestern

Composición espacial y temporal de la avifauna de humedales pequeños costeros y hábitat adyacentes en el noroeste de Baja California, MéxicoSpatial and temporal composition of the avifauna from small coastal wetlands and adjacent habitats in northwestern Baja California, Mexico

This region has recently undergone changes in land use. Housing developments have sprung up in the northern part, while the southern part has seen increased agricultural activity (Hernández, 2004), the most affected habitats being the estuaries and fresh-water lagoons currently under study (Hernández, 2004). These changes can negatively affect the species that use these biotopes, such as the Snowy Plover Charadrius alexandrinus, which prefers unfragmented areas for feeding and breeding (Escofet and Espejel, 1999). To mini- mize the effects and risks of biodiversity loss an appropriate management plan is needed, derived from good field data. We therefore studied the composition of the aquatic and terrestrial birds from 13 small coastal wetlands and adjacent habitats in northwestern Baja California, documenting their temporal and spatial dynamics in greater detail than in previous works. Materials and methods

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A Deinosuchus riograndensis (Eusuchia: Alligatoroidea)  from Coahuila, North Mexico

A Deinosuchus riograndensis (Eusuchia: Alligatoroidea) from Coahuila, North Mexico

Material. The material described here is housed at the pal- aeontological collection of the Museo del Desierto (MUDE), Saltillo, Coahuila and is accessible under the collection number CPC 484. It comprises six teeth and tooth fragments (CPC 484/1; CPC 484/2; CPC 484/3; CPC 484/4; CPC 484/5; CPC 484/6; Figure 3), a sixth or seventh cervical vertebra (CPC 484/7; Figure 4 a-f), a caudal vertebra (CPC 484/8; Figure 4 g-l), an accessory cervical left osteoderm (CPC 484/9; Figure 4 p-s), and a ventral osteoderm from the gulothoracic area (CPC 484/10; Figure 4 m-o). Distribution. Lower member of the Aguja Formation (Late Cretaceous, late Campanian) in the La Salada, Ocampo district, northwestern Coahuila, Mexico (Figures 1, 2). Description. Teeth. The six tooth crowns show only chips of the enamel (CPC 484/5 and CPC 484/6; Figure 3 s-u) and are identifi ed as belonging to Deinosuchus considering the thickness of the enamel as the only diagnostic character. Two specimens (CPC 484/3 and CPC 484/4; Figure 3 m-r) represent fragments of tooth crowns. One of them (CPC 484/4; Figure 3 p-r) lacks the apex and base. The second (CPC 484/3; Figure 3 m-o) lacks the apex and a section of the basolingual enamel, but the dentine core is preserved to the base of the crown. The crown height is reconstructed to about 40 mm with a basal diameter of about 20 mm. The tooth crowns CPC 484/1 (Figure 3 a-f) and CPC 484/2 (Figure 3 g-l) are complete with the enamel preserved to the apex. At the crown base, chips of the enamel have fl aked off and the dentine core is exposed there. Crown CPC 484/2 (Figure 3 g-l) lacks the entire root and a bit of the crown base. The crown height is 49 mm with a maxi- mum basal diameter of 29.3 mm and a minimum one of is 26.9 mm. On the labial face, a chip of enamel is missing. Crown CPC 484/1 (Figure 3 a-f) is the most complete of the six specimens, because the apical fourth of the root is preserved. With a crown height of 48.6 mm it is the largest of crowns. The diameter at the crown base is 29 mm, it is circular in cross section. Both teeth show one (CPC 484/1) or two cracks (CPC 484/2) respectively, that run from the

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Conectividad de arrecifes coralinos del noroeste del golfo de México utilizando un modelo LagrangianoConnectivity of mesophotic coral reefs in the northwestern Gulf of Mexico using a Lagrangian particle tracking model

Conectividad de arrecifes coralinos del noroeste del golfo de México utilizando un modelo LagrangianoConnectivity of mesophotic coral reefs in the northwestern Gulf of Mexico using a Lagrangian particle tracking model

Recently at the Texas continental shelf, northwestern Gulf of Mexico, six mesophotic coral reefs (MCRs) were described: Baker Bank, Arkansas Bank, Dream Bank, Black Fish Ridge, Mysterious Bank, and Harte Bank. In order to understand the ecology of these reefs, it is important to carry out studies of their connectivity with local reefs, as well as with remote reefs like those on the Texas-Louisiana shelf (Flower Garden Bank) or those on the Mexican shelf. A particle-tracking model was implemented to simulate the Lagrangian trajectories of numerical particles which represent larvae released by the coral colonies located at the Texas MCRs. The HYbrid Coordinate Ocean Model (HYCOM) provided the Eulerian fields of the three- dimensional velocity. Particle-advection experiments were carried out for different climatic scenarios of the ocean currents: a general experiment based on a climatological-mean (period 2010-2013) velocity field, and two experiments for climatic anomalies, enhanced velocities induced by hurricane “Alex” (July 2010) and by an intense cold-front season (November 2013). The results show that the connectivity is mostly local, among the 6 MCRs with a persistent northward flux of larvae; the highest connectivity occurs among Black Fish Ridge, Mysterious Bank and Harte Bank sites, shortly after (8-10 days) the release of the larvae. This general pattern can be different during climatic anomalies (hurricane and enhanced cold fronts), increasing the probability for larvae dispersal to other locations. The connectivity becomes also affected when biological behavior (reproductive season, buoyancy, and mortality) is included in the development of the larvae, improving the ecological links among the MCRs, which highlights the importance of such a behavior as a factor in the dispersion of the species.

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