Sindicador de canales de noticias
Biología reproductiva de Bothrops alternatus en un área templada de América del Sur: ciclo reproductivo masculino; Reproductive biology of Bothrops alternatus in a South America template area: male reproductive cycle
Bellini, Gisela Paola; Arzamendia, Vanesa; Alberto, Diana Mariel; Giraudo, Alejandro Raul
La yarará grande Bothrops alternatus es una especie de serpiente venenosa ampliamente distribuida y abundante en el área templada de América del Sur. Sin embargo el conocimiento sobre su biología reproductiva es mayormente conocido por datos de poblaciones brasileñas, existiendo escasos datos de las poblaciones argentinas. La historia de vida de las serpientes está influenciada por factores ecológicos como las variaciones regionales en las estaciones climáticas, generando diferencias en la biología reproductiva entre las poblaciones de diferentes regiones. Presentamos el ciclo reproductivo masculino de B. alternatus en su límite de distribución austral, basado en datos morfo-anatómicos e histológicos. El volumen testicular varió a lo largo de las estaciones, coincidiendo su aumento y disminución con el aumento y disminución de la temperatura. Sin embargo, las medidas morfo-anatómicas no mostraron todos los diferentes estadios por los que atraviesa el testículo de B. alternatus. En primavera los testículos estuvieron en recrudescencia y en verano comenzó la espermiogénesis que se extendió hasta el inicio del otoño (abril). La regresión testicular comenzó en mayo (otoño) y en invierno el epitelio seminífero de los testículos se retrae totalmente, encontrándose en regresión total hacia julio y hasta comienzos de septiembre (invierno). Los machos de B. alternatus estuvieron reproductivamente activos durante la primavera / verano y reproductivamente inactivos durante el otoño / invierno, determinando un ciclo reproductivo estacional. No obstante, se encontraron espermatozoides en los túbulos deferentes a lo largo de todos los meses del año. Con este estudio, aportamos evidencia para apoyar la importancia del enfoque microscópico para los estudios de los ciclos reproductivos. Finalmente, discutimos la sincronización del ciclo reproductivo masculino con el ciclo femenino en la población más austral de B. alternatus.; The pitviper Bothrops alternatus is one of the most widely distributed and abundant venomous snake species in the South America template area. However, knowledge about their reproductive biology is mostly known for data from Brazilian populations, finding few data for the Argentine populations. The life history of snakes is influenced by ecological factors such asregional variations in climatic seasons, generating differences in reproductive biology between populations in different regions. We present the male reproductive cycle of B. alternatus at its southern distribution limit, based on morpho-anatomical and histological data. The testicular volume varied throughout the seasons, coinciding its increase and decrease with the increaseand decrease in temperature. However, the morpho-anatomical measures did not show all the different stages through which the B. alternatus testicle passes. In spring the testicles were in recrudescence and in summer began the spermiogenesis that extended until the beginning of autumn (April). Testicular regression began in May (autumn) and in winter the seminiferous epithelium of the testicles retracts completely, being in total regression towards July and until the beginning of September (winter). Males of B. alternatus were reproductively active during spring / summer and reproductively inactive during autumn / winter, determining a seasonal reproductive cycle. However, sperm were found in the deferens ducts throughout all the year.With this study, we provide evidence to support the importance of the microscopic approach for studies of reproductive cycles. Finally, we discuss the synchronization of the male reproductive cycle with the female reproductive cycle in the southernmost population of B. alternatus.
Optical and electrical optimization of all-perovskite pin type junction tandem solar cells
Optical and electrical optimization of all-perovskite pin type junction tandem solar cells
Soldera, Marcos Maximiliano; Koffman Frischknecht, Alejandro; Taretto, Kurt Rodolfo
A definitive breakthrough of perovskite solar cells towards large scale industrialization is believed to be the demonstration of higher efficiencies than conventional silicon technology, suggesting the exploration of perovskite tandem cell configurations. Since high efficiency tandem solar cells require careful optimization of photoactive as well as contact and additional functional layers, we propose an optical-electrical model to obtain the optimum layer thicknesses and the attainable electrical output parameters of two-terminal perovskite-perovskite tandem solar cells. The optical model takes into account the coherent propagation of light through the layer stack comprising two perovskite semiconductors and the corresponding contact layers, while the electrical model assumes two series-connected analytical current/voltage equations for pin solar cells. This model allows to assess the impact of the main physical parameters on each perovskite layer without requiring the high specificity needed in more rigorous numerical simulations. Efficiencies above 34 % are predicted considering available perovskites with non-optimum bandgap and contact materials already proven in efficient laboratory solar cells. The requisite to attain such efficiencies is that recombination at the interfaces between the perovskite and contact materials is kept low in both bottom and top cells. Furthermore, within the assumption of non-optimum bandgaps of currently available perovskites, the simulation results suggest that efficiencies around 37 % are possible when adopting contact materials with smaller absorption, more adequate refraction indices, and lower resistivity.
Anti-Quorum Sensing Activity of Argentinean Honey and Effect of pH on Main Flavonoids
Anti-Quorum Sensing Activity of Argentinean Honey and Effect of pH on Main Flavonoids
Chiappe, Cristina Susana; Iurlina, Miriam Ofelia; Saiz, Amelia Ivone
In this study, the anti-QS activity of regional floral honey from the southeast region of Argentina was investigated using the bacterial model Chromobacterium violaceum. In addition, the anti-QS activity of quercetin, myricetin and luteolin was evaluated in an acidic medium. Two of the tested honey samples had the capacity to exert a notable anti-QS effect on C. violaceum. The effect of quercetin on the anti-QS activity at pH 5.8 was higher than myricetin and luteolin. The results obtained from the identification of quercetin, myricetin and luteolin of the honey extracts by High-Performance Liquid Chromatography (HPLC) showed that quercetin was the main flavonoid followed by myricetin and luteolin. It was observed that honey with high values of quercetin and high value of free acidity, exerted a greater effect on the inhibition of QS. Thus, we can conclude that an umbral value of pH seems to be necessary to increase the anti-QS activity of quercetin.
Los monstruos de la razón
Los monstruos de la razón
Vignale, Silvana Paola
Hay algo de precipitado y riesgoso en intentar pensar ?en movimiento? sobre algo que está sucediendo. En ese sentido, es necesario siempre hacerlo desde los acontecimientos y desde las prácticas, y no desde conceptos que en un momento comienzan a funcionar como universales; y en ejercicio crítico del pensamiento, no intentar dar respuestas, sino delimitar cuál es hoy nuestro problema. En ese caso, conviene salir del único registro de la excepcionalidad como paradigma de la gubernamentalidad biopolítica, así como del de la defensa de las libertades formales que reaviva la fobia al Estado. Puede que estén cambiando las condiciones de posibilidad de nuestra experiencia histórica, aunque aún no sepamos cuál será esa deriva, y que la coincidencia temporal con los acontecimientos nos obscurezca en qué direcciones eso esté cambiando. Sin embargo, eso no quiere decir que tengamos que quedarnos impávidos, nos insta a una actitud de alerta.
Cretaceous tetrapod tracks from Italy: a treasure trove of exceptional biodiversity
Cretaceous tetrapod tracks from Italy: a treasure trove of exceptional biodiversity
Petti, Fabio Massimo; Antonelli, Mateo; Citton, Paolo; Mariotti, Nino; Petruzzelli, Marco; Pignatti, Johannes; D’Orazi Porchetti, Simone; Romano, Marco; Sacchi, Eva; Sacco, Enrico; Wagensommer, Alexander
After about thirty years of investigation, the Cretaceous tetrapod track record from Italy has proved to be a ‘Rosetta Stone’ for improving understanding of the palaeogeographical and palaeoenvironmental evolution of the peri-Adriatic area. In the present contribution, we summarize current knowledge and diferent interpretations proposed on the basis of twelve ichnosites from northern, central and southern Italy. The tetrapod track record is represented by few ichnosites in the earliest Cretaceous, with the bulk of the record reported from carbonate platform deposits of the Aptian-Cenomanian interval and, in the Late Cretaceous, from a extensive-tracksite in Apulia preserving thousands of dinosaur footprints. On the whole, the ichnological diversity documented by the material indicates a high diversity of trackmakers, among which are sauropods, diferent kinds of theropods, ankylosaurs and hadrosaurs. The persistent occurrence of dinosaur footprints at diferent stratigraphic levels produced significant questions and constituted a dramatic constraint for the understanding of palaeogeographical and geodynamical evolution of the Mediterranean area during the Mesozoic, suggesting new and diferent interpretations that challenged previous reconstructions.
Extranuclear structural components that mediate dynamic chromosome movements in yeast meiosis
Extranuclear structural components that mediate dynamic chromosome movements in yeast meiosis
Lee, Chih Ying; Bisig, Carlos Gaston; Conrad, Michael M.; Ditamo, Yanina; Previato de Almeida, Luciana; Dresser, Michael E.; Pezza, Roberto J.
Telomere-led rapid chromosome movements or rapid prophase movements direct fundamental meiotic processes required for successful haploidization of the genome. Critical components of the machinery that generates rapid prophase movements are unknown, and the mechanism underlying rapid prophase movements remains poorly understood. We identified S. cerevisiae Mps2 as the outer nuclear membrane protein that connects the LINC complex with the cytoskeleton. We also demonstrate that the motor Myo2 works together with Mps2 to couple the telomeres to the actin cytoskeleton. Further, we show that Csm4 interacts with Mps2 and is required for perinuclear localization of Myo2, implicating Csm4 as a regulator of the Mps2-Myo2 interaction. We propose a model in which the newly identified functions of Mps2 and Myo2 cooperate with Csm4 to drive chromosome movements in meiotic prophase by coupling telomeres to the actin cytoskeleton.
Obtención de espectros usando un smartphone en la clase de Física
Obtención de espectros usando un smartphone en la clase de Física
Szigety, Esteban Guillermo; Bernal, Luis Jaime; Bilbao, Luis Ernesto; Pérez, Gabriel Horacio
Este artículo presenta los fundamentos para convertir un teléfono inteligente (o smartphone) en un espectrómetro casero. Utilizando un Compact Disc Digital Audio y una ranura ubicada adecuadamente se puede observar, entre otros, el espectro de emisión de una lámpara fluorescente compacta. Además, en este trabajo se incluyen los pasos metodológicos para medir las líneas de Fraunhofer del Sol de mayor ancho espectral. La propuesta está pensada para llevar adelante una clase práctica de espectros lumínicos tanto en instituciones de educación media como así también en cursos introductorios de física universitaria.; This article presents the basics for converting a smartphone as a home spectrometer. Using a Compact Disc Digital Audio and a properly located slot, the emission spectrum of a compact fluorescent lamp and other sources can be observed. This work includes the methodological steps to measure the Fraunhofer's lines of the sun with the greatest spectral width. The proposal is designed to carry out a practical class of light spectra both from institutions of secondary education as well as in introductory courses in university physics.
Las resistencias a las "relaciones carnales" con Estados Unidos (1990-2015)
Las resistencias a las "relaciones carnales" con Estados Unidos (1990-2015); The resistance to ‘carnal relations’ with the United States (1990-2015)
Morgenfeld, Leandro Ariel
Desde que asumió, en 1989, Menem planteó un giro en el vínculo con Estados Unidos, priorizando las "relaciones carnales", denominación que se popularizó a partir de una frase del canciller Guido Di Tella. Si bien logró un cierto consenso en esa política exterior más alineada con Washington, la misma tuvo sus detractores internos. En este artículo se analizan las resistencias a esa orientación en tres momentos claves: las expresiones de rechazo a las visitas de Bush (1990) y Clinton (1997) y las movilizaciones contra la invasión a Irak (2003) y las acciones contra Bush Jr y el ALCA (2005). En ese período de 15 años, en el que se produjo el inicio, auge y declive de ese estrecho alineamiento con la principal potencia, fueron importantes las expresiones de resistencia, que en general se soslayan o minimizan en los estudios de la historia de la política exterior argentina.; Since he took office in 1989, Carlos Saúl Menem proposed a new orientation in the link with the United States, prioritizing the “carnal relations”, a name that was popularized by a phrase of Foreign Minister Guido Di Tella. Although that foreign policy, more aligned with Washington, achieved a certain consensus, it had its internal detractors. In this article the resistance to this orientation is analyzed in three key moments: the expressions of rejection of the visits of Bush (1990) and Clinton (1997) and the protests against the invasion of Iraq (2003) and the actions against Bush Jr. and the FTAA (2005). In this period of 15 years, in which there was the beginning, rise and decline of this close link with the main foreign power, the expressions of resistance were important, despite being generally ignored or minimized in the studies of the history of Argentine foreign policy.
Arabidopsis thaliana SURFEIT1-like genes link mitochondrial function to early plant development and hormonal growth responses
Arabidopsis thaliana SURFEIT1-like genes link mitochondrial function to early plant development and hormonal growth responses
Gras, Diana Ester; Mansilla, Natanael; Rodriguez, Carina; Welchen, Elina; Gonzalez, Daniel Hector
Mutations in SURFEIT1 (SURF1) genes affect cytochrome c oxidase (COX) levels in different prokaryotic and eukaryotic organisms. In this work, we report that Arabidopsis thaliana has two genes that potentially encode SURF1 proteins, as a result of a duplication that took place in Brassicaceae. Both genes encode mitochondrial proteins and mutation in AtSURF1a causes embryonic lethality. Mutation in AtSURF1b, instead, causes defects in hypocotyl elongation under growth-stimulating conditions, such as low light intensity, increased ambient temperature and incubation with glucose. Mutants in AtSURF1b show reduced expression of the auxin reporter DR5:GUS and increased levels of the gibberellin reporter GFP-RGA, suggesting that auxin and gibberellin homeostasis are affected. In agreement, growth defects caused by AtSURF1b mutation can be overcome by treatment with indole-3-acetic acid and gibberellin A3, and also by increasing expression of the auxin biosynthesis gene YUC8 or the transcription factor PIF4, which shows lower abundance in AtSURF1b-deficient plants. Mutants in AtSURF1b display lower COX levels, higher alternative oxidase and superoxide levels, and increased expression of genes that respond to mitochondrial dysfunction. Decreased hypocotyl growth and DR5:GUS expression can be reversed by treatment with reduced glutathione, suggesting that redox changes, probably related to mitochondrial dysfunction, are responsible for the effect of AtSURF1b deficiency on hormone responses. The results indicate that changes in AtSURF1b affect mitochondrial function and the production of reactive oxygen species, which, in turn, impinges on a growth regulatory circuit that involves auxin, gibberellins and the transcription factor PIF4.
Short-range regulatory chromatin loops in plants
Short-range regulatory chromatin loops in plants
Gagliardi, Delfina; Manavella, Pablo Andrés
In all eukaryotic organisms, gene expression correlates with the condensation state of the chromatin. Highly packed genome regions, known as heterochromatins, are associated with repressed loci, whereas euchromatic regions represent a relaxed state of the chromatin actively transcribed. However, even in these active regions, associations between chromatin domains dynamically modify genome topology and alter gene expression. Long-range interaction within and between chromosomes determines chromatin domains that help to coordinate transcriptional events. On the other hand, short-range chromatin interactions emerged as dynamic mechanisms regulating the expression of specific loci. Our current capacity to decipher genome topology at high resolution allowed us to identify numerous cases of short-range regulatory chromatin interactions, which are reviewed in this Insight article.
Solidification, macrostructure and shrinkage formation of ductile and compacted irons
Solidification, macrostructure and shrinkage formation of ductile and compacted irons
Boeri, Roberto Enrique; López, Marcos Gabriel; Tenaglia, Nicolás Emanuel; Massone, Juan Miguel
This manuscript summarizes recent investigation of the authors into the solidification and shrinkage defect formation of ductile and compacted graphite cast irons. The study makes use of the DAAS (direct austempering after solidification) technique, developed earlier by some of the authors, to reveal the solidification grains. In addition, color metallography is used to reveal the microsegregation pattern. The formation of shrinkage defects is related to both the solidification macrostructure and the microsegregation pattern. The examination of the macrostructure shows that large solidification grains, composed by dendritic austenite and graphite, characterize the solidification of compacted graphite irons of carbon equivalent values ranging from hypoeutectic to hypereutectic. Similar results are observed for ductile iron, but in this case, the hypereutectic irons display a finer macrostructure. The characteristics of the primary austenite dendrites are revealed by the microsegregation pattern, which is exposed by the color etching reagent. This pattern also clarifies the nature of the interaction between the growing austenite and the compact and spheroidal graphite particles. The microshrinkage cavities in both ductile and compacted graphite irons form at the interior of the austenite grains, where fluid feeding cannot compensate the contraction of the last-to-freeze portions of the melt. Schematics of the solidification of ductile and compacted irons are proposed, accounting for the experimental observations.
Discovering the biogeographic history using predefined areas and explicit geographical data in the South American Liolaemus elongatus group (Iguania: Liolaemidae)
Discovering the biogeographic history using predefined areas and explicit geographical data in the South American Liolaemus elongatus group (Iguania: Liolaemidae)
Ruiz, Maria Soledad; Portelli, Sabrina Noelia; Hibbard, Thomas Nathaniel; Quinteros, Andres Sebastian
The genus Liolaemus includes 268 species, classified in two subgenera, Eulaemus and Liolaemus sensu stricto. The latter is formed by 12 monophyletic groups; one of them being the Liolaemus elongatus group, distributed in South America. We studied the biogeographic history of the L. elongatus group. We obtained a phylogenetic hypothesis recovering five main clades: the L. punmahuida, L. elongatus sensu stricto, L. kriegi, L. petrophilus and L. capillitas clades. Based on that hypothesis we obtained a time calibrated tree. The ancestral ranges were estimated applying three methodologies: DEC, DEC+j (using predefined areas) and GEM (using explicit geographical data). Our results show that the ancestral area of the L. elongatus group was located in central Argentina, and its divergence began around 11.5 Mya. From here, a combination of events (founder events and/or vicariances) led the species to their current distribution. Despite their differences, DEC+j and GEM show congruent results.
Transgression of cooperative helping norms outweighs children's intergroup bias
Transgression of cooperative helping norms outweighs children's intergroup bias
González Gadea, María Luz; Santamaria Garcia, Hernando; Aragón, Irina; Santamaría García, José; Herrera, Eduar; Ibañez, Agustin Mariano; Sigman, Mariano
Some forms of cooperative helping do not bind people from a moral perspective but ensure the functioning of social groups. Here, we have assessed how children coordinate such nonobligatory social concerns with group identity concerns. We have performed three studies (3–11-years-old; N = 393) aimed at testing children's peer preferences and resource allocation toward neutral individuals that engage in helping and hindering behaviors toward in-group and out-group peers. In Study 1, we have found that, in helping contexts, children prioritized group concerns and exhibited in-group favoritism. In hindering contexts, they privileged helping norms and did not exhibit out-group derogation. In Studies 2 and 3, we have confirmed that transgressions of cooperative helping norms outweighed intergroup bias. Our results suggest that, when cooperative helping norms conflict with group identity concerns, helping norms take priority. When these principles are coextensive and not in conflict, children give priority to group concerns.
Aerial Load Transportation with Multiple Quadrotors Based on a Kinematic Controller and a Neural SMC Dynamic Compensation
Aerial Load Transportation with Multiple Quadrotors Based on a Kinematic Controller and a Neural SMC Dynamic Compensation
Rossomando, Francisco Guido; Rosales, Claudio Dario; Gimenez, Javier; Salinas, Lucio Rafael; Soria, Carlos; Sarcinelli Filho, Mario; Carelli Albarracin, Ricardo Oscar
A novel formation control to transport a cable-suspended payload with two quadrotors is presented. The control structure is based on a layered scheme combining a kinematic null-space based controller and a neural sliding mode controller. The null-space controller is designed to generate velocity references to the quadrotors in the formation, whereas the neural sliding mode controller receives such reference velocities and performs a dynamic compensation for possible parametric uncertainties as well as for the dynamic perturbations caused by the load attached to the quadrotors. The stability of the closed-loop control system thus implemented is also proven with basis on the theory of Lyapunov. Very detailed dynamic models for the quadrotors, the flexible cables, and the payload are included in a highly realistic scenario. To close the work, numerical simulations are presented, whose results demonstrate a good performance of the proposed controller.
Cranial Anatomy and Paleoneurology of the Extinct Sloth Catonyx tarijensis (Xenarthra, Mylodontidae) From the Late Pleistocene of Oruro, Southwestern Bolivia
Cranial Anatomy and Paleoneurology of the Extinct Sloth Catonyx tarijensis (Xenarthra, Mylodontidae) From the Late Pleistocene of Oruro, Southwestern Bolivia
Boscaini, Alberto; Iurino, Dawid A.; Mamani Quispe, Bernardino; Andrade Flores, Rubén; Sardella, Raffaele; Pujos, François Roger Francis; Gaudin, Timothy
Extinct scelidotheriine sloths are among the most peculiar fossil mammals from South America. In recent decades, the external cranial anatomy of Pleistocene scelidotheres such as Scelidotherium, Catonyx, and Valgipes has been the subject of numerous studies, but their endocranial anatomy remains almost completely unknown. Today, computed tomographic (CT) scanning methodologies permit the exploration of previously inaccessible anatomical areas through a completely non-destructive process. For this reason, we undertook an analysis of the external and internal cranial anatomy of Catonyx tarijensis from the late Pleistocene of the Department of Oruro, in southwestern Bolivia. One particularly well-preserved specimen allowed detailed observation of all the main cranial osteological features, including the ear region and an almost complete hyoid apparatus, previously unknown for this taxon. Moreover, CT-scanning and subsequent elaboration of digital models of this specimen allowed observation of the brain cavity and cranial sinuses, and reconstruction of the trajectory of the main cranial nerves for the first time in an extinct scelidotheriine sloth. Additionally, we recovered the first three-dimensional reconstructions of the nasal cavity and the turbinates of an extinct sloth. In contrast to the usual depiction, the combined information from the external and internal anatomy suggests reduced lingual protrusion in Catonyx tarijensis, or at least a consistently more limited protrusion of the tongue in comparison with other mylodontid sloths such as Glossotherium robustum. The new morphological information recovered from this extinct sloth is compared with the available information for both extant and extinct forms, providing insights in the paleobiology of the extinct species. The present study reveals the importance of applying these novel non-destructive techniques to elucidate the evolutionary history of sloths.
Progesterone for the treatment of central nervous system disorders: the many signaling roads for a single molecule
Progesterone for the treatment of central nervous system disorders: the many signaling roads for a single molecule
Gonzalez, Susana Laura
Central nervous system (CNS) injuries and neurodegenerative diseases show a broad spectrum of common pathophysiological processes, including oxidative stress, neuroinflammation, excitotoxicity, demyelination and neurotransmission dysfunctions. Over the past decades, valuable experimental investigations have helped to clarify the role and timing of these multiple molecular and cellular mechanisms in each of these particular disorders, which usually overlap and critically contribute to long-term disability. However, up to now, no definite cures or effective disease-modifying therapies are available for any of these conditions. This has led to an active search of novel therapeutic approaches, including the repositioning of existing drugs for new indications, as a valid approach to promptly move candidate molecules to clinical trials. Progesterone, a steroid with a crucial role in the reproductive function in mammals, stands as one of these promising repositioning molecules to modulate the complex array of cellular and molecular events observed in several of these central nervous system diseases (Stein and Sayeed, 2019). Indeed, a great number of preclinical studies have provided solid basis for supporting a protective effect of progesterone in stroke, traumatic brain injury, spinal cord trauma, central and peripheral neuropathies, multiple sclerosis, and Alzheimer’s and Parkinson’s disease (González et al., 2019, 2020). Notwithstanding this remarkable number of studies exploring the beneficial effects of progesterone in CNS disorders, few of them offer a deeper look at the different receptors and complex signaling cascades involved. This perspective aims at expanding our view on the variety of receptors and signaling pathways that might be involved in progesterone-mediated actions in the nervous system as part of a rational strategy to promote a successful translation of steroid-based therapies for the treatment of neurological diseases.
Contribuciones para una crítica de la economía político-libidinal
Contribuciones para una crítica de la economía político-libidinal
Exposto, Emiliano; Rodriguez Varela, Gabriel
El ensayo examina la relación inmanente entre deseo inconsciente y valor en la sociedad productora de mercancías. La hipótesis es la siguiente: el valor es el sujeto del trabajo inconsciente del deseo en el capitalismo. Es en ese marco que se formula la categoría crítica deseo del Valor. La cual, entendida como proceso relacional específicamente moderno, refiere a la dinámica inconsciente de la producción social alienada a la forma abstracta del capital.; The essay examines the immanent relationship between unconscious desire and value in the commodity-producing society. The hypothesis is as follows: value is the subject of the unconscious work of desire in capitalism. It is within that framework that the critical desire category of Value is formulated. Which, understood as a specifically modern relational process, refers to the unconscious dynamics of social production alienated from the abstract form of capital.
Análisis morfométrico de cenizas volcánicas por microscopía holográfica digital
Análisis morfométrico de cenizas volcánicas por microscopía holográfica digital; Morphometric análisis of vulcanic ashes by digital holografic microscopy
Martinez, María Florencia; Monaldi, Andrea Carolina; Romero, Gladis Graciela; Blanc, Adriana Verónica; Baez, Walter Ariel
Las cenizas volcánicas presentan formas, texturas y tamaños altamente irregulares. Estas características influyen en su comportamiento aerodinámico, velocidad de sedimentación y dispersión, distancias de desplazamiento, etc. En particular, su morfología brinda información sobre los mecanismos de fragmentación que ocurren durante una erupción, distintos estilos eruptivos, propiedades del magma y es una herramienta de gran utilidad para el modelado de plumas volcánicas. En este trabajo se aborda el estudio morfológico de cenizas volcánicas empleando microscopía holográfica digital. A partir del cálculo de parámetros de tamaño y forma, se lleva a cabo una caracterización morfológica-textural y granulométrica en dos y tres dimensiones de las muestras y una clasificación según el mecanismo de fragmentación del proceso eruptivo.; Volcanic ashes features, such as their shapes, textures and sizes, influence their aerodynamic behavior, travel distances, sedimentation and dispersion rates. In particular, their morphology provides information about the fragmentation mechanisms during an eruption, different eruptive styles, magma properties and also is a valuable tool for modeling volcanic plumes. In this work, digital holographic microscopy is used in order to perform a morphological analysis of ashes. A morphological, textural and granulometric 2D and 3D characterization is developed through the calculation of shape and size parameters along with a classification according to the fragmentation mechanism of the eruptive process.
Restitution of Human Remains and Landscape Resignification
Restitution of Human Remains and Landscape Resignification
Curtoni, Rafael Pedro; Heider, Guillermo; Chaparro, Maria Gabriela; Tuninetti, Ángel
The restitution of human remains is a process wherein diverse agencies and meanings emerge. In Argentina there has been a significant increase of these processes, as well as claims of human bodies, during the early twenty-first century, allowing the appearance of new actors, the reconfiguration of public policies, and varied academic approaches. This article deals with a seldom-studied phenomenon-resignification of the territory as a consequence of a restitution-focusing on a recent example that involved the Rankülche Nation, an Indigenous nation in central Argentina, and its relationship with the government of La Pampa province, with scientists, and with members of the local community.
Emotional stress induces structural plasticity in Bergmann glial cells via an AC5–CPEB3–GluA1 pathway
Emotional stress induces structural plasticity in Bergmann glial cells via an AC5–CPEB3–GluA1 pathway
Bender, Crhistian Luis; Sun, Xingxing; Farooq, Muhammad; Yang, Qian; Davison, Caroline; Maroteaux, Matthieu; Huang, Yi Shuian; Ishikawa, Yoshihiro; Liu, Siqiong June
Stress alters brain function by modifying the structure and function of neurons and astrocytes. The fine processes of astrocytes are critical for the clearance of neurotransmitters during synaptic transmission. Thus, experience-dependent remodeling of glial processes is anticipated to alter the output of neural circuits. However, the molecular mechanisms that underlie glial structural plasticity are not known. Here we show that a single exposure of male and female mice to an acute stress produced a long-lasting retraction of the lateral processes of cerebellar Bergmann glial cells. These cells express the GluA1 subunit of AMPA-type glutamate receptors, and GluA1 knockdown is known to shorten the length of glial processes. We found that stress reduced the level of GluA1 protein and AMPA receptor-mediated currents in Bergmann glial cells, and these effects were absent in mice devoid of CPEB3, a protein that binds to GluA1 mRNA and regulates GluA1 protein synthesis. Administration of a b-adrenergic receptor blocker attenuated the reduction in GluA1, and deletion of adenylate cyclase 5 prevented GluA1 suppression. Therefore, stress suppresses GluA1 protein synthesis via an adrenergic/adenylyl cyclase/CPEB3 pathway, and reduces the length of astrocyte lateral processes. Our results identify a novel mechanism for GluA1 subunit plasticity in non-neuronal cells and suggest a previously unappreciated role for AMPA receptors in stress-induced astrocytic remodeling.
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