134 research outputs found
Book Review: War and the Politics Identity: The Making of Enemies and Allies in the Horn of Africa
No full textSemir Yesuf
Author: Kjetil Tornvoll
Title: War and the Politics Identity: The Making of Enemies and Allies in the Horn of Africa
New York: James Currey, 2009
 
Representation of symmetry in the extrastriate visual cortex from temporal integration of parts: An EEG/ERP study
No full textWhen symmetry is present in the retinal image, a symmetry-sensitive network in the extrastriate visual areas activates, and response magnitude scales with degree of regularity. Is this activation driven by the regularity in the image, or can the network recover regularity of an object? We investigated whether the network responds to bilateral symmetry for dynamically occluded shapes, and thus responds to symmetry in the object. The stimulus was an irregular shape partly occluded by a rectangle. After 500 ms, the rectangle was displaced to the other side, occluding the previously visible half, and revealing the other half for 1000 ms. Therefore, no symmetry was present in the image at any point in time. Exp.1 and Exp.2 used vertical and horizontal axis of reflection, and in Exp. 3 there was no occluder. Participants could detect symmetry with >80% accuracy. More importantly, ERP analysis showed a symmetry-specific response from ∼300 ms after presentation of the second half of the shape. When integration was made from halves of asymmetric whole shapes (Exp.4), and when symmetry was not task-relevant (Exp.5), no symmetry response was recorded. The results show, for the first time, an electrophysiological evidence of symmetry representation in the brain obtained by assembling information over time into a unitary gestalt. The integration process occurs when observers look for symmetric matches between the parts, and only if these are perceived as belonging to the same object
Estimating shear wave velocity using acceleration data in Antakya (Turkey)
No full textThis manuscript presents a site response analysis and an estimation of S-wave velocity that are dependent on acceleration data. First, existing data, such as density, seismic wave velocity, and soil cross-sections, are obtained from previous seismic microzonation studies and used to prepare input data for a suite of MATLAB routines, which are referred to as SUA software. Acceleration data are obtained from four free-field strong-motion stations of the SERAMAR project, which was conducted between 2006 and 2009 in conjunction with a Turkish-German joint research project, and inputted into the software as basic data. The results include a 1D velocity cross-section versus depth and an amplification model of the site. Three different depth levels can be determined for the ranges of 0-5 m, 5-15 m and 15-25 m. The seismic velocities vary between 380 and 470 m s-1 for the first 5 m; 320 and 480 m s-1 for 5-15 m; and 470 and 750 m s-1 for 15-25 m. These results are comparable with the amplification values from the microtremor data from previous studies. The 1D velocity models are appropriate for the soil conditions.
Resumen
Este trabajo presenta el análisis a una respuesta de sitio y una estimación de la velocidad de la onda de corte que son dependientes de la información de aceleración. Los datos adicionales como la densidad, la velocidad de onda sísmica y los cortes transversales de suelo, se obtuvieron de estudios previos de microzonificación sísmica y se utilizaron para preparar el registro de datos en una plataforma de rutinas MATLAB, que se refieren al software SUA. Los datos de información de la aceleración se tomaron de cuatro estaciones de monitoreo de movimientos fuertes a campo abierto del proyecto SERAMAR, que se realizó entre 2006 y 2009 en una investigación conjunta turco-alemana, y se ingresaron en el programa como la información básica. Los resultados incluyen una sección cruzada de velocidad 1D versus profundidad y el modelo amplificado del sitio. Se pudieron determinar tres niveles diferentes a partir de los rangos de 0-5 m, 5-15 m y 15-25 m. Las velocidades sísmicas pueden variar entre 380 y 470 m s-1 para los primeros 5 metros; 320 y 480 m s-1 para el rango 5-15 m, y 450 y 750 m s-1 para el rango 15-25 m. Estos resultados son comparables con los valores de amplificación del perfil Microtemor de estudios previos. Los modelos de velocidad 1D son apropiados para las condiciones del suelo
Geophysical Data (Gravity and Magnetic) from the Area Between Adana, Kahramanmaras and Hatay in the Eastern Mediterranean Region: Tectonic Implications
No full textThe gravity and magnetic maps of the area between Adana–Kahramanmaras–Hatay provinces were produced from a compilation of data gathered during the period between 1973 and 1989. Reduced to the pole (RTP) and pseudo-gravity transformation (PGT) methods were applied to the magnetic data, while derivative ratio (DR) processing was applied to both gravity and magnetic data, respectively. Bouguer, RTP and PGT maps show the image of a buried structure corresponding to ophiolites under undifferentiated Quaternary deposits in the Adana depression and Iskenderun Gulf. DR maps show two important faults which reflect the tectonic framework in the study area: (1) the Karatas–Osmaniye Fault extending from Osmaniye to Karatas in the south between Adana and Iskenderun depressions and (2) Amanos Fault (southern part of East Anatolian Fault) in the Hatay region running southward from Turkoglu to Amik Basin along Amanos Mountain forming the actual plate boundary between the Anatolian block (part of Eurasian plate) and Arabian plate
Kinematics of the East Anatolian Fault Zone between Turkoglu (Kahramanmaras) and Celikhan (Adiyaman), eastern Turkey
No full textIn this study we determined the stress regime acting along the East Anatolian Fault Zone between Turkoglu (Kahramanmaras) and Celikhan (Adiyaman), from the Neocene to present-day, based on the inversion of striations measured on faults and on the focal mechanisms of earthquakes having magnitudes greater than 5.0. The inversions yield a strike-slip stress regime with a reverse component (i.e., transpression) operative in the Neocene to present with a consistent N-to NW-trending or, axis 156 +/- 11 degrees and an E- to NE-trending sigma(3) axis, sigma(7) 9 degrees sigma(3), producing left-lateral motion along the East Anatolian Fault Zone. The inversions of focal mechanisms yield a strike-slip stress deviator characterized by an approximately N-S (N1 degrees W)-trending sigma(1), and an approximately E-W (N89 degrees E)-trending sigma(3) axis. Both the kinematic analysis and structural observations indicate that the stress regime operating in the study area has had a transpressional character, giving rise to the Mio-Pliocene compressive structures (reverse faults, thrusts and folds) observed in the study area. Field observations allow estimation of a Pliocene age for the strike-slip East Anatolian Fault Zone
Book Review: War and the Politics of Identity: The Making of Enemies and Allies in the Horn of Africa
No full textTitle of the Book: War and the Politics of Identity: The Making of Enemies and Allies in the Horn of Africa
Author of the Book: Kjetil Tornvoll
Publisher: James Currey: New York
Year of Publication: 200
Neuroarthistory : Discovering a Greater Appreciation of Art Through Science
No full textiv, 90 p.The author reviews several themes of neuroarthistory from theories of aesthetic interest, light perception and the eye, and the visual brain, considering the critical work of John Onians, Margaret Livingston, Semir Zeki, Tim Adams, Eric Fernie, Dominic Lopes, and V. S. Ramachandran
Sustained response to symmetry in extrastriate areas after stimulus offset: An EEG study
No full textElectrophysiological (EEG) studies of human perception have found that amplitude at posterior electrodes is more negative for symmetrical patterns compared to asymmetrical patterns. This negativity lasts for hundreds of milliseconds and it has been called sustained posterior negativity (SPN). Symmetry activates a network of visual areas, including the lateral occipital complex (LOC). The SPN is a response to presence of symmetry in the image. Given the sustained nature of this activation, in this study we tested the persistence of the SPN after stimulus offset. Two shapes were presented (for 0.5 s each) with a 1 s blank interval in between. We observed a sustained response after stimulus offset, irrespective of whether the task required processing of shape information. This supports the idea that the response to symmetry is generated by information in the image, independently of task, and that it is sustained over approximately one second post stimulus onset
Neurobiology and the humanities.
No full textCan the arts and humanities contribute significantly to the study of the brain? Similar brain processes are involved in humanistic and scientific inference, and in this essay, I argue that conclusions reached by one are relevant to the other
A synthesis: Late Cenozoic stress field distribution at northeastern corner of the Eastern Mediterranean, SE Turkey
No full text- …
