67 research outputs found

    First record of Early Devonian (Lochkovian) flora from the Santa Rosa Formation - Alarache, Southern Bolivia

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    New information on plants and palynomorphs from Angosto de Alarache, South Bolivia, is presented. The plant remains appear at the base of the section. Dichotomizing sterile forms are assigned to Hostinella sp. and scarce stems terminated in spherical structures are interpreted as indetermined sporangia. The palynological association 1 recovered from this level contains abundant phytodebris, trilete spores, few cryptospores, algae, very poorly preserved chitinozoans, and other elements (fungi, ?lichens). Trilete spores assignable to Apiculiretusispora sp., Punctatisporites sp. and Retusotriletes sp., are obtained from the maceration of some isolated sporangia. The dichotomous branching of the stems and the trilete spores recovered from the isolated sporangia support its tracheophyte affinity. The palynological assemblage 2, obtained three metres above, contains abundant phytodebris and more diverse palynomorphs. Two new species (Retusotriletes albarinii n. sp., Acinosporites macgregorii n. sp.) are described. Based on the presence of the trilete spores Dictyotriletes emsiensis (ALLEN) MCGREGOR, Retusotriletes maculatus MCGREGOR and CAMFIELD, Apiculiretusispora plicata (ALLEN) STREEL and the absence, mainly of Verrucosisporites polygonalis LANNINGER and Urochitina loboi VOLKHEIMER et al., we propose a Lochkovian age but restricted up to the Late not latest Lochkovian, and the correlation with the lower part of the Emsiensis Zone of the Amazon Basin and the MN Zone of Western Europe. The abundance of fragmented stems of varied size and parallel to bedding planes, along with the isolated sporangia in the plant assemblage suggests a short distance transportation under low energy conditions, probably from marginal palaeoenvironments to low energy marine settings

    Devonian palynological assemblages from the San Antonio x-1 Borehole, Tarija Basin, northwestern Argentina

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    The palynological analysis of the 2548-3628 m interval of the San Antonio x-1 Borehole in northwestern Argentina is presented. The illustrated palynoflora is composed of 96 species represented by diverse palynological groups such as trilete spores and cryptospores (46 species), microplankton (39 species), chitinozoans (7 species), scolecodonts, and some remaining specimens in open nomenclature and as incertae sedis. One new species, Retusotriletes ottonei, is described. Thirty-four species are first records in the Argentinean Devonian. Three assemblages (SA1, SA2, and SA3) are defined based on the presence, absence, or abundance of groups of taxa. The presence of Grandispora protea and Grandispora douglastownense among others in the assemblage SA1 is indicative of a late Emsian to mid-Eifelian age. The concurrence of Acinosporites macrospinosus and A. acanthomammillatus in the assemblage SA2 is indicative of a late Eifelian-mid Givetian and is also supported by the appearance of several other species such as Chomotriletes vedugensis, Dibolisporites farraginis and Biharisporites parviornatus. An early Frasnian age is associated to the assemblage SA3 on the basis of the appearances of Lunulidia micropunctata, Pseudolunulidia laevigata, Verrucosisporites bulliferus and the abundance of Maranhites. The assemblages SA1 and SA2 reflect a nearshore, shallow marine depositional conditions, characterized by a high terrestrial input and variable marine influence, while the assemblage SA3 could represent a transgression during that time. The assemblages are composed of many cosmpolitan index species that support a partial correlation with Brazilian and Euramerican zonations resulting from the effects of paleolatitude and the configuration of land and sea for that time, with a narrow Rheic Ocean between northern Gondwana and Euramerica

    Morfología y estructura de la megaspora Lagenoisporites magnus (Chi y Hills) Candilier et al. 1982 del Carbonífero inferior de Bolivia

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    Se estudió la morfología y estructura de megasporas asignadas a Lagenoisporites magnus provenientes de la Formación Toregua, Grupo Retama, Tournaisiano medio-tardío de Bolivia. El análisis se realizó con microscopía óptica, fluorescencia y electrónica de barrido. Las megasporas examinadas, en su mayoría comprimidas lateralmente, presentan un cuerpo esferoidal con una gula proximal del tipo hologula. La longitud, incluyendo a la gula, es de 290-510 μm y el ancho de 184-390 μm según el eje ecuatorial.Facultad de Ciencias Naturales y Muse

    Morfología y estructura de la megaspora Lagenoisporites magnus (Chi y Hills) Candilier et al. 1982 del Carbonífero inferior de Bolivia

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    Se estudió la morfología y estructura de megasporas asignadas a Lagenoisporites magnus provenientes de la Formación Toregua, Grupo Retama, Tournaisiano medio-tardío de Bolivia. El análisis se realizó con microscopía óptica, fluorescencia y electrónica de barrido. Las megasporas examinadas, en su mayoría comprimidas lateralmente, presentan un cuerpo esferoidal con una gula proximal del tipo hologula. La longitud, incluyendo a la gula, es de 290-510 μm y el ancho de 184-390 μm según el eje ecuatorial.Facultad de Ciencias Naturales y Muse

    Hegemonía, ecología y problemática ambiental

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    Fil: Di pasquo, Federico. Universidad de Buenos Aires. Grupo de Filosofía de la Biología. Buenos Aires, Argentina.Fil: Del Castillo, Daniela. Universidad de Buenos Aires. Grupo de Filosofía de la Biología. Buenos Aires, Argentina.Fil: Busan, Tomás. Universidad de Buenos Aires. Grupo de Filosofía de la Biología. Buenos Aires, Argentina.Fil: Klier, Gabriela. Universidad Nacional de Río Negro. CITECDE. Río Negro, ArgentinaWe uphold the view that, in the international context of environmental issues, an hegemonic conception of nature is presented, given by the notion of ecosystem. In the first place, we show the way in which this ecological conception of nature “saturates” the context of the environmental crisis, becoming a “compulsory medium” for the different actors involved. Secondly, we highlight three features that are assigned to this ecological study unit and that partially explain its hegemonic character: the ecosystem is considered a unit with no defined space-time dimension; the ecosystem is considered a unit that allows the human species incorporation and the ecosystem is considered a unit that precedes the experience of its researchers. Finally, we suggest three unintended consequences of this hegemonic conception for the environmental issues.Keywords:Marc Angenot; nature; ecosystem; international programs.Sostenemos que en el contexto internacional de la problemática ambiental se presenta una concepción hegemónica de naturaleza, dada por la noción de ecosistema. En primer lugar, mostramos el modo en que esta concepción ecológica de naturaleza satura el contexto de la crisis ambiental, deviniendo en un medio obligado para los diferentes actores involucrados. En segundo lugar, destacamos tres características que le son asignadas a esta unidad de estudio ecológica y que explican, parcialmente, su carácter hegemónico: el ecosistema es considerado como una unidad sin dimensión espacio-temporal definida; el ecosistema es considerado como una unidad que permite incorporar a la especie humana y el ecosistema es considerado como una unidad que es anterior a la experiencia de sus investigadores e investigadoras. Finalmente, sugerimos tres consecuencias no deseadas de esta concepción hegemónica para las problemáticas ambientales

    Prenatal diagnosis and outcome of fetuses with isolated agenesis of septum pellucidum: cohort study and meta-analysis

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    Objective: To evaluate the postnatal outcome of children with a prenatal diagnosis of apparently isolated agenesis of the septum pellucidum (ASP). Methods: A retrospective cohort study of cases of prenatally diagnosed ASP followed in two tertiary centers and a meta-analysis combining data from the cohort study with data from published studies identified in a systematic review were carried out. Only cases with apparently isolated ASP on antenatal ultrasound and/or magnetic resonance imaging and with available postnatal follow-up data were considered eligible for inclusion. The following outcomes were analyzed: incidence of chromosomal anomalies, agreement between antenatal and postnatal findings, overall incidence of septo-optic dysplasia (SOD) and incidence of major neurological disability (motor, language, coordination or behavioral disorder or epilepsy) in non-SOD children. The incidence of SOD in infants with apparently normal optic pathways on antenatal imaging was also evaluated. Results: Fifteen cases of isolated ASP, with median postnatal follow-up of 36 months (range, 12-60 months), were selected from the two centers. Six previously published studies met the inclusion criteria for the systematic review and a total of 78 cases were eligible for the analysis, including the 15 cases from our series. Genetic tests were carried out antenatally in 30 fetuses, of which two had an abnormal result (pooled proportion, 9.0% (95% CI, 1.8-20.7%); I2  = 0%). Additional or discordant imaging findings were noted postnatally in 9/70 (pooled proportion, 13.7% (95% CI, 3.5-29.0%); I2  = 63.9%) cases. Of all 78 neonates with available follow-up, SOD was diagnosed postnatally in 14 (pooled proportion, 19.4% (95% CI, 8.6-33.2%); I2  = 51.2%). In 60 cases, the optic pathways were considered to be normal on antenatal imaging, and six of these (pooled proportion, 9.1% (95% CI, 1.1-24.0%); I2  = 62.0%) were diagnosed postnatally with SOD. Of the 46 infants with available neurological follow-up who were not affected by SOD, a major neurological disability was diagnosed in three (pooled proportion, 6.5% (95% CI, 0.5-18.6%); I2  = 40.1%). Conclusions: In the vast majority of cases with a prenatal diagnosis of apparently isolated ASP, the prognosis is favorable. However, an additional anomaly is detected after birth in about 14% of cases and has a negative impact on clinical outcome. Detailed antenatal assessment of the brain and optic pathways is strongly recommended in order to identify the presence of associated anomalies. Antenatal visualization of apparently normal optic pathways does not rule out SOD. © 2021 International Society of Ultrasound in Obstetrics and Gynecology

    Usefulness of an Intrapartum Ultrasound Simulator (IUSim™) for Midwife Training: Results from an RCT

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    Introduction: We conducted a randomized study to determine whether a training session on a dedicated simulator (IUSim™) would facilitate the midwives in learning the technique of transperineal intrapartum ultrasound. Methods: Following a 30-min multimedia presentation including images and videos on how to obtain and measure the angle of progression (AoP) and the head-perineum distance (HPD), 6 midwives with no prior experience in intrapartum ultrasound were randomly split into 2 groups: 3 of them were assigned to the "training group"and 3 to the "control group."The midwives belonging to the former group were taught to measure the 2 sonographic parameters during a 3-h practical session conducted on IUSim™ under the supervision of an expert obstetrician. In the following 3 months, all the 6 midwives were asked to independently perform transperineal ultrasound during their clinical practice and to measure on the acquired images either the AoP or the HPD. The sonographic images were examined in blind by the teaching obstetrician who assigned a 0-3 score to the image quality (IQS) and to the measurement quality (MQS). Results: A total of 48 ultrasound images (24 patients) from 5 midwives were acquired and included in the study analysis. A midwife of the "training group"declined participation after the practical session. Independently from the randomization group, the image quality score (IQS + MQS) was significantly higher for the HPD compared with the AoP (2.5 ± 0.66 vs. 1.79 ± 1.14; p = 0.01). In the training group, the MQS of either AoP (2.66 ± 0.5 vs.1.46 ± 1.45. p = 0.038) and the HPD (2.9 ± 0.33 vs. 1.87 ± 0.83 p = 0.002) was significantly higher in comparison with the control group, while the IQS of both measurements was comparable between the 2 groups (1.91 ± 1.24 vs. 2.25 ± 0.865; p = 0.28). Conclusion: The use of a dedicated simulator may facilitate the midwives in learning how to measure the AoP and the HPD on transperineal ultrasound images

    Biostratigraphy and paleoecology of an unusual palynological record from the Aquidauana Formation, Late Pennsylvanian of Paraná Basin

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    The Aquidauana Formation is a Permo-Carboniferous sedimentary unit, widely stratigraphicaly distributed in the northwestern and northern portions of the Paraná Basin. However, little paleontological data is available from this formation, preventing accurate biostratigraphic and paleoecological interpretations. An abundant, diversified and well preserved assemblage of palynomorphs was recognized from sampling conducted in an outcrop section in Cipolândia District of Aquidauana Municipality, state of Mato Grosso do Sul, Brazil. A total of 35 indigenous palynomorph taxa was recognized, comprising 6 species of spores (related to 5 genera), 28 species of pollen grains (14 genera) and 1 species of chlorophycean algae. Monosaccate pollen grains are exceptionally dominant, representing 90.38% of the association, particularly constituted by species of the genera Cannanoropollis (30.41% of the total assemblage), Potonieisporites (28.14%) and Plicatipollenites (19.52%). This quantitative overrepresentation is not usual from Gondwana deposits, revealing a particular plant dominance of Cordaitales in the terrestrial flora. These results are interpreted as an upland ecology characterized by plants with a moisture-independent reproduction strategy, under a glacial climate influence. Certain species of pollen allow assignment of this assemblage to the Crucisaccites monoletus Zone (Late Pennsylvanian), which had been recognized only in the middle portion of the Itararé Group at the northeastern margin of the basin
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