340 research outputs found
Neural Correlates of Opponent Processes for Financial Gains and Losses
Objective: Functional imaging studies offer alternative explanations for the neural correlates of monetary gain and loss related brain activity, and their opponents, omission of gains and losses. One possible explanation based on the psychology of opponent process theory suggests that successful avoidance of an aversive outcome is itself rewarding, and hence activates brain regions involved in reward processing. In order to test this hypothesis, we compared brain activation for successful avoidance of losses and receipt of monetary gains. Additionally, the brain regions involved in processing of frustrative neutral outcomes and actual losses were compared in order to test whether these two representations are coded in common or distinct brain regions. Methods: Using a 3 Tesla functional magnetic resonance imaging machine, fifteen healthy volunteers between the ages 22 to 28 were scanned for blood oxygen level dependent signal changes while they were performing a probabilistic learning task, wherein each trial a participant chose one of the two available options in order to win or avoid losing money. Results: The results confirmed, previous findings showing that medial frontal cortex and ventral striatum show significant activation (p<0.001) not only for monetary gains but also for successful avoidance of losses. A similar activation pattern was also observed for monetary losses and avoidance of gains in the medial frontal cortex, and posterior cingulate cortex, however, there was increased activation in amygdala specific to monetary losses (p<0.001). Further, subtraction analysis showed that regardless of the type of loss (i.e., frustrative neutral outcomes) posterior insula showed increased activation. Conclusion: This study provides evidence for a significant overlap not only between gains and losses, but also between their opponents. The results suggested that the overlapping activity pattern in the medial frontal cortex could be explained by a more abstract function of medial frontal cortex, such as outcome evaluation or performance monitoring, which possibly does not differentiate between winning and losing monetary outcomes.Peer reviewedFinal Published versio
Geothermal Potential of the Sığacık Gulf (Seferihisar) and Preliminary Investigations with Seismic and Magnetic Surveys
AbstractSığacık Gulf is located in the southern part of the Karaburun Peninsula in the Aegean Region. This region is restricted by two important ridges; Karaburun and Seferihisar Ridges. In order to determine the geothermal and marine hot springs, marine shallow seismic and magnetic surveys were applied in 2011. Approximately 250km seismic reflection data were collected by Dokuz Eylül-1 vessel. As preliminary results of seismic and magnetic surveys, authors suggest that Sığacık Gulf may have geothermal potential or hot water springs on the sea-floor. Determined negative gravity anomalies should be investigated with multi-disciplinary surveys (CTD, marine-chemistry, side scan sonar, etc.)
Human Uniqueness, Cognition by Description, and Procedural Memory
Evidence will be reviewed suggesting a fairly direct link between the human ability to think about entities which one has never perceived — here called “cognition by description” — and procedural memory. Cognition by description is a uniquely hominid trait which makes religion, science, and history possible. It is hypothesized that cognition by description (in the manner of Bertrand Russell’s “knowledge by description”) requires variable binding, which in turn utilizes quantifier raising. Quantifier raising plausibly depends upon the computational core of language, specifically the element of it which Noam Chomsky calls “internal Merge”. Internal Merge produces hierarchical structures by means of a memory of derivational steps, a process plausibly involving procedural memory. The hypothesis is testable, predicting that procedural memory deficits will be accompanied by impairments in cognition by description. We also discuss neural mechanisms plausibly underlying procedural memory and also, by our hypothesis, cognition by description
Structure and Growth of Core–shell Nanoprecipitates in Al–Er–Sc–Zr–V–Si High-temperature Alloys
Lightweight Sc-containing aluminum alloys exhibit superior mechanical performance at high temperatures due to core–shell, L12-ordered trialuminide nanoprecipitates. In this study, the structure of these nanoprecipitates was studied, using different transmission electron microscopy (TEM) techniques, for an Al–Er– Sc–Zr–V–Si alloy that was subjected to a two-stage overaging heat treatment. Energy-dispersive X-ray spectroscopy of the spherical Al3(Sc, Zr, Er ,V) nanoprecipitates revealed a core–shell structure with an Sc- and Er-enriched core and a Zr-enriched shell, without a clear V outer shell. This structure is stable up to 72% of the absolute melting temperature of Al for extended periods of time. High-angle annular dark-field scanning TEM was used to image the {100} planes of the nanoprecipitates, demonstrating a homogeneous L12-ordered superlattice structure for the entire nanoprecipitates, despite the variations in the concentrations of solute atoms within the unit cells. A possible growth path and compositional trajectory for these nanoprecipitates was proposed using high-resolution TEM observations, where different rod-like structural defects were detected, which are considered to be precursors to the spherical L12-ordered nanoprecipitates. It is also hypothesized that the structural defects could consist of segregated Si; however, this was not possible to verify with HAADF-STEM because of the small differences in Al and Si atomic numbers. The results herein allow a better understanding of how the Al–Sc alloys’ core–shell nanoprecipitates form and evolve temporally, thereby providing a better physical picture for future atomistic structural mappings and simulations
Mechanical Behavior of Three-Dimensional Braided Nickel-Based Superalloys Synthesized via Pack Cementation
Braided tubes of Ni-based superalloys are fabricated via three-dimensional (3-D) braiding of ductile Ni-20Cr (wt pct) wires followed by post-textile gas-phase alloying with Al and Ti to create, after homogenization and aging, γ/γ′ strengthened lightweight, porous structures. Tensile tests reveal an increase in strength by 100 MPa compared to as-braided Ni-20Cr (wt pct). An interrupted tensile test, combined with X-ray tomographic scans between each step, sheds light on the failure behavior of the braided superalloy tubes
Experimental and Modeling Study of Compressive Creep In 3D-Woven Ni-Based Superalloys
Micro-architectured Ni-based superalloy structures, with Ni-20Cr-3Ti-2Al (wt.%) composition and γ/γ′-microstructure, are created by a multi-step process: (i) non-crimp orthogonal 3D-weaving of ductile, 202 μm diameter Ni-20%Cr wires, (ii) gas-phase alloying with Al and Ti, (iii) simultaneous transient-liquid phase (TLP) bonding between wires and homogenization within wires via interdiffusion, (iv) solutionizing to create a single-phase solid solution, and (v) aging to precipitate the γ′ phase. The creep behavior of these 3D-woven γ/γ′ nickel-based superalloys is studied under uniaxial compression via experiments at 825 °C and via finite element (FE) analysis, using a 3D model of the woven structures obtained through X-ray micro-tomography. The creep strain rate for the woven Ni-based superalloy is higher than that for the bulk superalloy due to the lower solid volume fraction of the woven structure, while the creep exponents are identical. The compressive creep behavior is sensitive to the geometry of the woven structures: fewer wires perpendicular to the load and fewer bonds between wires cause lower creep resistance of the woven structure, due to a reduction in load transfer from the longitudinal wires (which are primarily load-bearing) and the perpendicular wires. Creep buckling of longitudinal wires drastically reduces creep resistance of the woven structure, confirming the importance of maintaining longitudinal wires vertical and parallel to the uniaxial compression direction. Finally, reducing wire cross-section, e.g., via oxidation, reduces creep resistance. The oxidation kinetics of the wire structures at 750, 825, and 900 °C displayed parabolic rate constants comparable to commercial Ni-based superalloys, but indicates that up to 35% of the wire cross-section is oxidized after 7 days at 825 °C, such that oxidation-resistant coatings are needed for long-term use in oxidative environment
Neurological Basis of Bodily Self-Consciousness and Related Psychopathologies
The change in the body awareness of people depending on the dynamic processing of the multisensory signals from the body has been revealed the bodily self-consciousness approach. Recent studies have proposed that the processing and integration of multisensory signals (i.e. vestibular, somatosensory) are fundamental requirement for bodily self-consciousness. Perception of body-parts and global aspect of whole body can dynamically change depending on the congruency between signals from multiple modalities (i.e. vestibular, somatosensory). The basic assumption of the studies investigating bodily self-consciousness is that the bodily experiences are related with the multisensory signal processing. The aim of the present article is to review how the bodily self-consciousness is studied experimentally and discuss the underlying sensory processes. In addition to that, we discussed the limitations of the previous experimental studies
Effects of Nb and Ta additions on the strength and coarsening resistance of precipitation-strengthened Al-Zr-Sc-Er-Si alloys
A dilute Al-0.07Zr-0.02Sc-0.005Er-0.06Si (at.%) alloy was microalloyed with 0.08 at.% Nb or Ta. Atom-probe tomography reveals that, upon aging, Nb and Ta partition to the coherent L12-Al3(Zr,Sc,Er) nanoprecipitates (with average concentrations of 0.2 and 0.08 at.%, respectively), with both segregating at the matrix/nanoprecipitate heterophase interface. This is consistent with the Nb- and Ta-modified alloys exhibiting, as compared to the unmodified alloy: (i) higher peak microhardness, from a higher nanoprecipitate volume fraction and/or lattice parameter mismatch; and (ii) improved aging resistance, from slower nanoprecipitate coarsening due to the small diffusivities of niobium and tantalum in aluminum. Analogous results were previously reported for a V-modified alloy
THE NEOTECTONIC STRUCTURE OF THE GÜLBAHÇE BAY
Gülbahçe Körfezi, tektonik olarak Miosen öncesi Ege'de egemen kuzey-güney (KG) doğrultulu sıkışma sonucu oluşmuş (KG), (KKD) ve (GGB) doğrultulu kırık ve çöküntülerin, bugün süren aynı doğrultudaki açılma sonucu meydana gelen (DB) doğrultulu kırık ve çöküntülerin kesim bölgesinde yer almaktadır. Bu bölge Batı Anadolu ve Ege'de ki blok rotasyonun etkisinde kalmakta olup, Orta Doğu Ege çöküntüsünü oluşturan yükselti ve çöküntü (Horst-Graben) sisteminde Karaburun yükseltisi ile Foça çöküntüsü arasında eşik görevi görmektedir. Bölgedeki bu durum yapılan gravite değerlendirmelerinde Batı-Doğu doğrultulu Karaburun-Yamanlar hattında birbirlerinden normal atımlı faylarla ayrılmış yükselti ve çukurlar ile geçiş eşikleri izlenmektedir. Gülbahçe çukurundaki sedimentler, su katmanları ile beraber 200 - 250 m kalınlığa ulaşmaktadır. Sismik değerlendirmelerde körfezde üstte Kuvaterner sedimentler onun altında ise Neojen volkanitlerden oluşan iki sismik tabaka paketi bulunmaktadır. İnce milli - killi seviyeler içeren kuvarterner sedimentleri, metan gazlarını yüzeye çıkaramayışı ve jeotermal etkinlikten dolayı yer yer şişme ve kıvrımlara neden olmaktadır. Bu durum 3.5 kHz yüksek ayrımlı sismik ve yanal taramalı sonar kayıtlarında izlenmektedir. Gülbahçe Bay is situated at the cross - sections of the fractures and depressions trending in the N-S and NNE-SSW produced by the dominant N-S trending compression that was tectonically effective before the miocene in the Aegean, and the fractures and depressions presently still effective in the E-W direction produced again by the same extensional regime. This region, which is under the influence of the block rotations of Western Turkey and Aegean, serves as the stepping segment between the Karaburun uplift and the Foça depression within the rift system forming the Central East Aegean depression. This situation was observed as the highs and lows which are separated from each other with normal faults, in the gravity evaluation of the E-W section along Karaburun to Yamanlar. Sediments together with water column reach to the depths of 200 - 250 m in the Gülbahçe depression. According to the seismic evaluations, there are two seismic layer packages in the Bay as the top Quaternary sediments and the Neogene volcanites below perturbances and foldings are produced by the silty - clayey layers within the quaternary sediments due to the accumulation of methane at the surface and the geothermal activity. These were observed on the 3.5 kHz high resolution seismics and as well as on the side scan sonar records
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