Desarrollo de superficies de aplanamiento disectadas sobre coast range en la Región del Maule, Chile Central

The fundaments of a geomorphological denomination for the coast range of Central Chile and the improvement of the corresponding theory are researched here. Three basic aspects were observed: presence of surfaces, deep weathering and tectonics. The modern theory of Rumpffäche was the central principle of analysis. It is deduced that the planation of the highest surface was favoured bydeep weathering, which is thought to have operated at least during the Miocene, supplying grus as principal material. The deep differential etching regulated valley incision. Starting from the principal valley, excavation of gigantic amphitheatres produced staircase surfaces, controlled by the weathering front. The presence of isolated homoclinal elevated surfaces and its incision by antecedent rivers, reveals post planation tectonic deformation. In order to denominate the coastal block,it is proposed the use of the terms coast range, for the morphostructure and Rumpffäche or etchplain, for the morhosculpture.Se investiga los fundamentos de una denominacion geomorfolgica para la cadena costera de Chile Central y del mejoramiento de la teoría correspondiente. Tres aspectos básicos fueron observados: presencia de superficies, meteorización profunda y tectónica. El principio fundamentalde análisis fue la teoría moderna de la Rumpfläche. Se deduce que el aplanamiento de la superficie más alta fue favorecido por la meteorización profunda, la cual debe haber operado al menos durante el Mioceno, proporcionando principalmente grus. El etching diferencial profundo reguló la incisión de valles. A partir del valle principal, la excavación de anfiteatros gigantes produjo superficies en peldaños, controladas por el frente de meteorización. La presencia de superficies homoclinales elevadas y aisladas, y su incisión por ríos antecedentes, indica deformación tectónica post-aplanamiento. Para denominar el bloque costero se propone usar los términos coast range, para la morfoestructura y Rumpffläche o etchplain, para la morfoescultura

Procesos submarinos de ruptura en el fondo del fiordo Aysén, Norpatagonia, Chile

The present work deals with the relationship between the dislocated sedimentary structures of fjord sub-bottom and the possible sequence of failures in the Aysén Fjordland. The longitudinal profile of the fjord was obtained by means of a 3.5 kHz sub-bottom profiler record, obtained on board of the Vidal Gormaz research vessel. The observations were principally carried out in the ponding esplanade located in the zone of seismic cluster below the fjord. Here, the deformations of the visible sub-bottom affect all the thickness of sediments. There are different styles of deformation of sediments, with greater breakup in the older than in most recent layers. Its 14 C and 210 Pb age extends since the Termination I (Last Glaciation) until the Upper Holocene. Between 1922 and 1995 the earthquake of 1927 happened, giving an inter-seismic period of 80 years until 2007. This earthquake affected with smaller deformation up to the most recent layers judging by its 210Pb age. A sub-bottom record post 2007 earthquake indicates disruptions of the tectonic structures recorded in1995. Therefore: a) the sub-superficial layers of ages between the Holocene and the Termination I can have been deformed also by earthquakes previous to 1927; b) these processes must be recurrent, sleeping, with renewed unbalances; c) its type of frequency must be episodic, oscillating between low (100 to 1000 years) and middle (0 to 100 years); d) its way of activity is by rupture; and e) the known frequency is between ancient-historical and recent historical (1 to 200 years BP or more).    Se estudia la relación entre estructuras sedimentarias dislocadas de sub-fondo y procesos de ruptura en el fiordo Aysén. El perfil longitudinal de éste fue obtenido mediante registros de un perfilador de subfondo a 3.5 kHz obtenidos a bordo del buque de investigación Vidal Gormaz. Las observaciones fueron hechas principalmente en la explanada de represamiento localizada en la zona de enjambre sísmico del fiordo. Aquí, las deformaciones del sub-fondo visible afectan todo el espesor de sedimentos. Hay diferentes estilos de deformación de sedimentos, con mayor ruptura en las capas más antiguas que en las más recientes. Su edad C14 y Pb210 se extiende desde la Terminación I (Última Glaciación) hasta el Holoceno Superior. Entre 1922 y 1995 sucedió el sismo de 1927, dando un período inter-sísmico de 80 años hasta 2007. Este sismo afectó con menor deformación a las capas más recientes según su edad Pb210 . Un registro post sismo 2007 indica rupturas en las estructuras tectónicas registradas en 1995. Por lo tanto: a) las capas sub-superficiales de edades entre el Holoceno y la Terminación I pueden haber sido deformadas también por sismos anteriores a 1927; b) estos procesos deben ser recurrentes, durmientes, con desbalances renovados; c) su tipo de frecuencia debe ser episódico, oscilando entre bajo (100 a 1000 años) y medio (0 a 100 años); d) su tipo de actividad es por ruptura; y e) la frecuencia conocida está entre histórica antigua e histórica reciente (1 a 200 años AP o más).  

Evolución de las vertientes y morfogénesis fluvial en el dominio subtropical seco según la carta geomorfológica detallada (ej.: Chile semi árido)

The sample area is located in the middle lower part of the Choapa river basin inChile (31° 30'S-71° 20'W). The principal forms of the landscape are: the mountainous slopes, the high terrace, the "bahadas" ("glacis colluviaux") and the small alluvial fans, the low terrace and the alluvial beds.The geomorphological map "sensu stricto" contains slope and fluvial processesand landforms. The morphogenetic context of the landforms is representedwith different colors, tonal gradations showing tbe age.The relative age of the morphogenesis is as follows:A. Remainders of culminating erosion surfaces, dissection of great valleysand erosional steps in middle slope: Neogene (N 1 and 2).B. High terrace: Lower Pleistocene (Q 1).C. Dissected valleys on the ancient high terrace: Middle Pleistocene (Q 2).D. "Glacis colluvial" (lower slope "bahada") over the high terrace, lowterrace and lateral alluvial fans: Upper Pleistocene (Q. 3) E. Dissection of glacis and lower terrace, preparation of tbe present dayslope morphogenetic system and polychronic continum of some surface processes: Holocene (Q 4).Tbe present day morphogenetic system is influenced by inherited and relictfeatures. as the morphological slope stepping and the deep regolith. which inIluences the micro-relief. The climatic analysis shows strong irregularities andthe human activity generates a break of equilibrium in the system. Soil creep and surface wash produces surface soil beheading. On the beheaded surface of the upper slope, mudflows can eventually be generated. Downward, gullies appear on the middle slope. Finally, the lower slope is depositional. Upper, middle and lower slope are related to a convex-concave slope upward the high terrace.The proposed evolutive model is the YOUNG, s (1977) 6th model for slopes:control by removal on upper and middle slope: control by accumulation on thelower slope; removal of regolith entirely by surface transport; rate of surfacetransport proportional to sen of the slope angle theta.El área muestra está localizada en la parte media inferior de la cuenca fluvialdel río Choapa (31° 30' S - 71° 20' W). Las principales formas del paisaje son:las vertientes de montaña, la alta terraza, los glacis coluviales y pequeñosconos aluviales, la terraza baja y los lechos aluviales.El mapa geomorfológico "sensu stricto" contiene procesos y formas de vertientesy fluviales. El contexto morfogenético de las formas está representadocon diferentes colores, cuyas gradaciones tonales muestran la edad.La edad relativa de la morfogenésis es como sigue:A. Testigos de superficies culminantes de erosión, dissección de grandesvalles y rellanos erosionales de media vertiente: Neógeno (N1 y N2).B. Terraza alta: Pleistoceno Inferior (Q 1).C. Valles disectados en la antígua terraza alta: Pleistoceno Medio (Q 2).D. Glacis coluvial sobre la terraza alta, terraza baja y conos de deyecciónlaterales: Pleistoceno Superior (Q 3 ).E. Disección de glacis y baja terraza, preparación del sistema morfogenéticoactual y secuencia policrónica de algunos procesos superficiales: Holoceno(Q 4).El sistema morfogenético actual está influído por rasgos heredados y relictos,como el escalonamiento morfológico de las vertientes y el profundo regolito, loscuales influyen en los micro-relieves. El análisis climático muestra fuertes irregularidades y la actividad humana genera una ruptura de equilibrio en el sistema. La reptación simple y el lavado superficial producen descabezamiento superficial del suelo. Corrientes de tierra y aún de barro pueden generarse eventualmente en la parte superior descabezada de la vertiente. Hacia abajo, aparecen las regueras de erosión sobre la vertiente media. Finalmente, la baja vertiente es deposicional. Se puede referir la alta, media y baja vertiente a una vertiente convexo-cóncava aguas arriba de la plataforma de la alta terraza.Para esta situación de vertientes, se propone un modelo evolutivo correspondiente al modelo 6 de YOUNG (1977) para las vertientes: el control evolutivo es por remoción en la veniente superior y media; el control es por acumulación en la vertient.e inferior; la remoción del regolito es enteramente por transporte superficial; el monto de transporte superficial es proporcional al seno de la de la pendiente teta

Influencias morfogenéticas de los desalineamientos y lineas de costa contrapuestas en el litoral de Chile central

Two morphostructural styles are present in the coastline Topocalrna - Pichilernu (34° - 34°30' S): a) Offset style with zeta bays and b) Offset style with crenulate coastlines and almost straight beaches. They are resulting from contraposed shorelines, as evidenced by overlapping softer desposits on crystalline hard rocks.Systern atributes are recognized in these styles by using components as offset angle,asymetry, orientation and curvature index. Correlation and matrices analysis indicate that 40 - 60% of the effects are explained by three components: offset angle, curvature index and azirmuth. Therefore, both of the styles may be recognized as subsystems.Each subsystem presents a different behaviour in front of wave environment Since offsetcondition and orientation explain curvature, each style receives differential wave attack, because refraction is well and positively correlated to curvature.Half heart shaped beaches and bays represent, therefore, both drift and swash alignment, depending on the offset angle and refraction of constructing waves. So, a logarithmic spiral may appear. Their maximum concavity is eroded during surges, meanwhile the downdrift part'can suffer depositional effect. This difference is not so clear in the almost rectilinear beaches of the other style. State and attack conditions depend, therefore, on the position in the bay. Dune system structures associated to beaches may be correlated to sedimentary budget and beach orientation. This fact must be taken into account in decision making processes concerning shore managernent

A Case of Reactive Cervical Lymphadenopathy with Fat Necrosis Impinging on Adjacent Vascular Structures.

A tender neck mass in adults can be a diagnostic challenge due to a wide differential diagnosis, which ranges from reactive lymphadenopathy to malignancy. In this report, we describe a case of a young female with an unusually large and tender reactive lymph node with fat necrosis. The diagnostic imaging findings alone mimicked that of scrofula and malignancy, which prompted a complete workup. Additionally, the enlarged lymph node was compressing the internal jugular vein in the setting of oral contraceptive use by the patient, raising concern for Lemierre's syndrome or internal jugular vein thrombosis. This report shows how, in the appropriate clinical context, and especially with the involvement of adjacent respiratory or neurovascular structures, aggressive diagnostic testing can be indicated

Distorted cyclotron line profile in Cep X-4 as observed by NuSTAR

We present spectral analysis of NuSTAR and Swift observations of Cep X-4 during its outburst in 2014. We observed the source once during the peak of the outburst and once during the decay, finding good agreement in the spectral shape between the observations. We describe the continuum using a powerlaw with a Fermi-Dirac cutoff at high energies. Cep X-4 has a very strong cyclotron resonant scattering feature (CRSF) around 30 keV. A simple absorption-like line with a Gaussian optical depth or a pseudo-Lorentzian profile both fail to describe the shape of the CRSF accurately, leaving significant deviations at the red side of the line. We characterize this asymmetry with a second absorption feature around 19 keV. The line energy of the CRSF, which is not influenced by the addition of this feature, shows a small but significant positive luminosity dependence. With luminosities between (1-6)e36 erg/s, Cep X-4 is below the theoretical limit where such a correlation is expected. This behavior is similar to Vela X-1 and we discuss parallels between the two systems.Comment: 6 pages, 4 figure, accepted for publication in ApJ letter

Interacting with the enemy: indirect effects of personality on conspecific aggression in crickets

In animal contests, individuals respond plastically to the phenotypes of the opponents that they confront. These ‘opponent’ – or ‘indirect’ – effects are often repeatable, e.g., certain opponents consistently elicit more or less aggressiveness in others. ‘Personality’ (repeatable among-individual variance in behavior) has been proposed as an important source of indirect effects. Here, we repeatedly assayed aggressiveness of wild-caught adult male field crickets Gryllus campestris in staged dyadic fights, measuring aggressiveness of both contestants. Measurements of their personality in non-social contexts (activity and exploration behavior) enabled us to ask whether personality caused indirect effects on aggressiveness. Activity, exploration, and aggressiveness were positively associated into a behavioral syndrome eliciting aggressiveness in conspecifics, providing direct evidence for the role of personality in causing indirect effects. Our findings imply that a multivariate view of phenotypes that includes indirect effects greatly improves our ability to understand the ecology and evolution of behavior

Pathways to Social Evolution and Their Evolutionary Feedbacks

In the context of social evolution, the ecological drivers of selection are the phenotypes of other individuals. The social environment can thus evolve, potentially changing the adaptive value for different social strategies. Different branches of evolutionary biology have traditionally focused on different aspects of these feedbacks. Here, we synthesize behavioral ecology theory concerning evolutionarily stable strategies when fitness is frequency dependent with quantitative genetic models providing statistical descriptions of evolutionary responses to social selection. Using path analyses, we review how social interactions influence the strength of selection and how social responsiveness, social impact, and non-random social assortment affect responses to social selection. We then detail how the frequency-dependent nature of social interactions fits into this framework and how it imposes selection on traits mediating social responsiveness, social impact, and social assortment, further affecting evolutionary dynamics. Throughout, we discuss the parameters in quantitative genetics models of social evolution from a behavioral ecology perspective and identify their statistical counterparts in empirical studies. This integration of behavioral ecology and quantitative genetic perspectives should lead to greater clarity in the generation of hypotheses and more focused empirical research regarding evolutionary pathways and feedbacks inherent in specific social interactions