Maximizing decision rate in multisensory integration

Effective decision-making in an uncertain world requires making use of all available information, even if distributed across different sensory modalities, as well as trading off the speed of a decision with its accuracy. In tasks with a fixed stimulus presentation time, animal and human subjects have previously been shown to combine information from several modalities in a statistically optimal manner. Furthermore, for easily discriminable stimuli and under the assumption that reaction times result from a race-to-threshold mechanism, multimodal reaction times are typically faster than predicted from unimodal conditions when assuming independent (parallel) races for each modality. However, due to a lack of adequate ideal observer models, it has remained unclear whether subjects perform optimal cue combination when they are allowed to choose their response times freely.
Based on data collected from human subjects performing a visual/vestibular heading discrimination task, we show that the subjects exhibit worse discrimination performance in the multimodal condition than predicted by standard cue combination criteria, which relate multimodal discrimination performance to sensitivity in the unimodal conditions. Furthermore, multimodal reaction times are slower than those predicted by a parallel race model, opposite to what is commonly observed for easily discriminable stimuli.
Despite violating the standard criteria for optimal cue combination, we show that subjects still accumulate evidence optimally across time and cues, even when the strength of the evidence varies with time. Additionally, subjects adjust their decision bounds, controlling the trade-off between speed and accuracy of a decision, such that they feature correct decision rates close to the maximum achievable value

Vestibular heading discrimination and sensitivity to linear acceleration in head and world coordinates

Effective navigation and locomotion depend critically on an observer\u27s ability to judge direction of linear self-motion, i.e., heading. The vestibular cue to heading is the direction of inertial acceleration that accompanies transient linear movements. This cue is transduced by the otolith organs. The otoliths also respond to gravitational acceleration, so vestibular heading discrimination could depend on (1) the direction of movement in head coordinates (i.e., relative to the otoliths), (2) the direction of movement in world coordinates (i.e., relative to gravity), or (3) body orientation (i.e., the direction of gravity relative to the otoliths). To quantify these effects, we measured vestibular and visual discrimination of heading along azimuth and elevation dimensions with observers oriented both upright and side-down relative to gravity. We compared vestibular heading thresholds with corresponding measurements of sensitivity to linear motion along lateral and vertical axes of the head (coarse direction discrimination and amplitude discrimination). Neither heading nor coarse direction thresholds depended on movement direction in world coordinates, demonstrating that the nervous system compensates for gravity. Instead, they depended similarly on movement direction in head coordinates (better performance in the horizontal plane) and on body orientation (better performance in the upright orientation). Heading thresholds were correlated with, but significantly larger than, predictions based on sensitivity in the coarse discrimination task. Simulations of a neuron/anti-neuron pair with idealized cosine-tuning properties show that heading thresholds larger than those predicted from coarse direction discrimination could be accounted for by an amplitude-response nonlinearity in the neural representation of inertial motion

Identifikasi landmark Sebagai penunjang karakter wisata sejarah Berdasarkan rute wisata bus macyto Di kota malang

ABSTRAK Kesulitan dalam menemukan arah, mengenali lingkungan sekitar dan menentukan rute yang tepat untuk menuju ke tempat yang diinginkan oleh wisatawan menjadi sesuatu yang akan menjadi tantangan bagi pembangunan yang ditujukan untuk membantu sektor kepariwisataan di Kota Malang. Penelitian ini akan fokus pada Landmark yang berhasil diidentifikasi oleh wisatawan serta yang memiliki aspek visual yang menarik dalam mengenalinya. Tujuan yang ingin dicapai adalah mengidentifikasi Landmark yang dapat membantu kegiatan navigasi wisatawan sepanjang rute wisata Bus MACYTO. Dengan jenis penelitian menggunakan pendekatan Kualitatif dan Mental Mapping diharapkan penelitian ini akan menghasilkan kajian tentang aspek visual dari estetika bentuk masing-masing Landmark berkarakter wisata sejarah juga fungsinya sebagai objek yang dapat menjadi titik orientasi wisatawan dan masyarakat Kota Malang. Hasil penelitian melalui Mental Mapping menunjukkan bahwa kehadiran Landmark membawa identitas dan mewakili kawasan koridor jalan seperti Kawasan Alun-Alun Merdeka, Kawasan Jl. Kawi, Kawasan Jl. Ijen, Kawasan Jl. Semeru dan Kawasan Alun-Alun Tugu. Dari 41 Landmark yang berhasil diidentifikasi, terdapat 20 Landmark yang dapat mencerminkan karakter sejarah di Kota Malang berdasarkan responden. Serta Landmark yang ideal sebagai navigator adalah Balai Kota Malang, Gereja Khatolik Hati Kudus Yesus Kayutangan, Alun-Alun Tugu, Gereja Katedral Ijen, Masjid Jami’ dan GPIB Immanuel. Kata kunci: Landmark, Wisata Sejarah, Rute Wisata Bus Macyt

Superparamagnetic Poly (3-hydroxybutyrate-co-3 hydroxyvalerate) (PHBV) nanoparticles for biomedical applications

Indexación: ScieloBackground: The progress in material science and the recent advances in biodegradable/biocompatible polymers and magnetic iron oxide nanoparticles have led to develop innovative diagnostic and therapeutic strategies for diseases based on multifunctional nanoparticles, which include contrast medium for magnetic resonance imaging, agent for hyperthermia and nanocarriers for targeted drug delivery. The aim of this work is to synthesize and characterize superparamagnetic iron oxide (magnetite), and to encapsulate them into poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles for biomedical applications. Results: The magnetite nanoparticles were confirmed by X-ray diffraction and exhibited a size of 22.3 ± 8.8 nm measured by transmission electron microscopy (TEM). Polymeric PHBV nanoparticles loaded with magnetite (MgNPs) were analyzed using dynamic light scattering and showed a size of 258.6 ± 35.7 nm and a negative zeta potential (-10.8 ± 3.5 mV). The TEM examination of MgNPs exhibited a spherical core-shell structure and the magnetic measurements showed in both, non-encapsulated magnetite and MgNPs, a superparamagnetic performance. Finally, the in vitro studies about the magnetic retention of MgNPs in a segment of small intestine of rats showed an active accumulation in the region of the magnetic field. Conclusions: The results obtained make the MgNPs suitable as potential magnetic resonance imaging contrast agents, also promoting hyperthermia and even as potential nanocarriers for site-specific transport and delivery of drugs. Keywords: hyperthermia, magnetic resonance image (MRI), magnetite, PHBV, polymeric nanoparticles.http://ref.scielo.org/cxt57

Dora Ann King and C.H. Dunaway in a Joint Junior Recital

This is the program for the joint junior recital of pianist Dora Ann King and organist C.H. Dunaway. The recital took place on February 17, 1966, in Mitchell Hall Auditorium