Cortical transformation of spatial processing for solving the cocktail party problem: a computational model(1,2,3).

In multisource, "cocktail party" sound environments, human and animal auditory systems can use spatial cues to effectively separate and follow one source of sound over competing sources. While mechanisms to extract spatial cues such as interaural time differences (ITDs) are well understood in precortical areas, how such information is reused and transformed in higher cortical regions to represent segregated sound sources is not clear. We present a computational model describing a hypothesized neural network that spans spatial cue detection areas and the cortex. This network is based on recent physiological findings that cortical neurons selectively encode target stimuli in the presence of competing maskers based on source locations (Maddox et al., 2012). We demonstrate that key features of cortical responses can be generated by the model network, which exploits spatial interactions between inputs via lateral inhibition, enabling the spatial separation of target and interfering sources while allowing monitoring of a broader acoustic space when there is no competition. We present the model network along with testable experimental paradigms as a starting point for understanding the transformation and organization of spatial information from midbrain to cortex. This network is then extended to suggest engineering solutions that may be useful for hearing-assistive devices in solving the cocktail party problem.R01 DC000100 - NIDCD NIH HHSPublished versio

Enhancement of Persistent Currents by Hubbard Interactions In Disordered 1D Rings: Avoided Level Crossings Interpretation

We study effects of local electron interactions on the persistent current of one dimensional disordered rings. For different realizations of disorder we compute the current as a function of Aharonov-Bohm flux to zeroth and first orders in the Hubbard interaction. We find that the persistent current is {\em enhanced} by onsite interactions. Using an avoided level crossings approach, we derive analytic formulas which explain the numerical results at weak disorder. The same approach also explains the opposite effect (suppression) found for spinless fermion models with intersite interactions.Comment: uuencoded: 17 pages, text in revtex, 7 figs in postscrip

Controlling the thermal contact resistance of a carbon nanotube heat spreader

The ability to tune the thermal resistance of carbon nanotube mechanical supports from insulating to conducting could permit the next generation of thermal management devices. Here, we demonstrate fabrication techniques for carbon nanotube supports that realize either weak or strong thermal coupling, selectively. Direct imaging by in-situ electron thermal microscopy shows that the thermal contact resistance of a nanotube weakly-coupled to its support is greater than 250 K*m/W and that this value can be reduced to 4.2(+5.6/-2.1) K*m/W by imbedding the nanotube in metal contacts

Kiss and Fly - a study of the impacts at a UK regional airport

In the light of the forecast growth in air transport the UK Government has placed a requirement on all airports with substantial air transport movements to implement surface access strategies. The emphasis of surface access policy has been to increase the proportion of people arriving at airports by public transport by a variety of means such as managing parking supply and pricing and improving public transport. The extent to which these policies will be effective will depend on a number of factors such as the quality and availability of the alternatives, the availability of competing off-site parking and the extent to which kiss and fly is feasible. This paper reports on two studies of passenger access to Leeds-Bradford International Airport in the summers of 2004 and 2005. The airport has an aspiration to increase public transport use to the airport from its current level of 3% to 10% by 2010. The principal means by which this is currently planned to be achieved is through the expansion of scheduled bus services to Leeds, Bradford and Harrogate. The 2004 study found that 49% of passengers were dropped off at the airport by friends and that the potential for larger quantities of people to reach the airport by conventional bus services was limited. The 2005 study investigated the extent to which these kiss and fly journeys generate extra travel on the road network. The results show that for an airport with around 2.5 million passengers the Kiss & Fly journeys are creating an extra 19.4 million kilometres, an increase of 36% over the distance that would have been travelled if people had driven and parked. The paper concludes that a charge levied on all vehicles accessing the airport, similar to a congestion charge, is likely to have the greatest impact on travel behaviour and will have a far greater impact on the environment than the current emphasis on public transport improvements and parking restrictions

Asymmetric frequency conversion in nonlinear systems driven by a biharmonic pump

A novel mechanism of asymmetric frequency conversion is investigated in nonlinear dispersive devices driven parametrically with a biharmonic pump. When the relative phase between the first and second harmonics combined in a two-tone pump is appropriately tuned, nonreciprocal frequency conversion, either upward or downward, can occur. Full directionality and efficiency of the conversion process is possible, provided that the distribution of pump power over the harmonics is set correctly. While this asymmetric conversion effect is generic, we describe its practical realization in a model system consisting of a current-biased, resistively-shunted Josephson junction (RSJ). Here, the multiharmonic Josephson oscillations, generated internally from the static current bias, provide the pump drive.Comment: 5+ pages, 4 pages supplement. Expanded and modified discussion, additional references and a new appendix in supplemental material detailing the calculation of Josephson harmonics in the RS

A physiologically inspired model for solving the cocktail party problem.

At a cocktail party, we can broadly monitor the entire acoustic scene to detect important cues (e.g., our names being called, or the fire alarm going off), or selectively listen to a target sound source (e.g., a conversation partner). It has recently been observed that individual neurons in the avian field L (analog to the mammalian auditory cortex) can display broad spatial tuning to single targets and selective tuning to a target embedded in spatially distributed sound mixtures. Here, we describe a model inspired by these experimental observations and apply it to process mixtures of human speech sentences. This processing is realized in the neural spiking domain. It converts binaural acoustic inputs into cortical spike trains using a multi-stage model composed of a cochlear filter-bank, a midbrain spatial-localization network, and a cortical network. The output spike trains of the cortical network are then converted back into an acoustic waveform, using a stimulus reconstruction technique. The intelligibility of the reconstructed output is quantified using an objective measure of speech intelligibility. We apply the algorithm to single and multi-talker speech to demonstrate that the physiologically inspired algorithm is able to achieve intelligible reconstruction of an "attended" target sentence embedded in two other non-attended masker sentences. The algorithm is also robust to masker level and displays performance trends comparable to humans. The ideas from this work may help improve the performance of hearing assistive devices (e.g., hearing aids and cochlear implants), speech-recognition technology, and computational algorithms for processing natural scenes cluttered with spatially distributed acoustic objects.R01 DC000100 - NIDCD NIH HHSPublished versio

A Systematic Transport and Thermodynamic Study of Heavy Transition Metal Oxides with Hexagonal Structure

There is no apparent, dominant interaction in heavy transition metal oxides (TMO), especially in 5d-TMO, where all relevant interactions are of comparable energy scales, and therefore strongly compete. In particular, the spin-orbit interaction (SOI) strongly competes with the electron-lattice and on-site Coulomb interaction (U). Therefore, any tool that allows one to tune the relative strengths of SOI and U is expected to offer an opportunity for the discovery and study of novel materials. BaIrO3 is a magnetic insulator driven by SOI whereas the isostructural BaRuO3 is a paramagnetic metal. The contrasting ground states have been shown to result from the critical role of the strong SOI in the iridate. This dissertation thoroughly examines a wide array of newly observed novel phenomena induced by adjusting the relative strengths of SOI and U via a systematic chemical substitution of the Ru4+(4d4) ions for Ir4+(5d5) ions in BaIrO3, i.e., in high quality single crystals of BaIr1-xRuxO3(0.0 \u3c x \u3c 1.0) . Our investigation of structural, magnetic, transport and thermal properties reveals that Ru substitution directly rebalances the competing energies so profoundly that it generates a rich phase diagram for BaIr1-xRuxO3 featuring two major effects: (1) Light Ru doping (0 \u3c x \u3c 0.15) prompts a simultaneous and precipitous drop in both the magnetic ordering temperature TC and the electrical resistivity, which exhibits metal-insulator transition at around TC. (2) Heavier Ru doping (0.41 \u3c x \u3c 0.82) induces a robust metallic and spin frustration state. For comparison and contrast, we also substituted Rh4+(4d5) ions for Ir4+(5d5) ions in BaIrO3, i.e. BaIr1-xRhxO3(0.0 \u3c x \u3c 0.10), where Rh only reduces the SOI, but without altering the band filling. Hence, this system remains tuned at the Mott instability and is very susceptible to disorder scattering which gives rise to Anderson localization

KOMERSIALISASI SEKS SIMBOLIK

Abstrak Penelitian ini dilakukan di daerah Wonokromo Surabaya dengan tujuan untuk mengetahui bentuk komersialisasi pelaku prostitusi remaja di stasiun Wonokromo. Fokus penelitian ini adalah pada praktik prostitusi oleh remaja. Dikarenakan maraknya perilaku menyimpang yang dilakukan oleh generasi muda.Penelitian ini menggunakan proposisi teoritik mengenai interaksi simbolik dari sudut pandang Herbert Mead, sebagai landasan untuk menganalisis simbol-simbol yang ada pada pekerja seks komersial. Metode yang digunakan adalah penelitian model kualitatif dengan pendekatan studi kasus. Penelitian ini menggunakan teknik wawancara dan observasi dalam penggalian data di lapangan. Dari hasil wawancara dapat digambarkan bahwasanya bentuk komersialisasi pelaku prostitusi remaja di stasiun Wonokromo Kota Surabaya sebuah fenomena yang berbeda. Hal tersebut bisa terlihat dari strategi pemasaran para pelaku prostitusi tersebut. Walaupun bisa dikatakan masih tertinggal dengan tempat prostitusi lain, yakni dolly sebagai tempat prostitusi terbesar di Asia Tenggara yang berada di kota Surabaya, akan tetapi hal ini pantas diberikan perhatian khusus.   Kata kunci: Simbol, Komersial, Seks  Abstract This research was conducted in Surabaya Wonokromo area in order to determine the practice of juvenile prostitutes commercialization Wonokromo station. The focus of this research is the practice of prostitution by juveniles. Due to the rise of deviant behavior committed by this muda.Penelitian generation using theoretical propositions regarding the symbolic interactionist perspective Herbert Mead, as a basis for analyzing the symbols that exist in the commercial sex workers. The method used was a qualitative research models with a case study approach. This study used interviews and observation techniques in penggalia data in the field. From the results can be described behold the form of commercialization of teenage prostitutes in Surabaya Wonokromo station a different phenomenon. It can be seen from the marketing strategy of the prostitutes. Although it can be said to be still left with another prostitution, namely Dolly as the largest prostitution in Southeast Asia in the city of Surabaya, but it is worth special attention. Keywords: Symbol, commercial, sex   *) Terima kasih  kepada Ardhie Raditya selaku mitra bestari yang telah mereview dan memberi masukan berharga terhadap naskah ini

Nonfactorization in Hadronic Two-body Cabibbo-favored decays of D^0 and D^+

With the inclusion of nonfactorized amplitudes in a scheme with $N_c=3$, we have studied Cabibbo-favored decays of $D^0$ and $D^+$ into two-body hadronic states involving two isospins in the final state. We have shown that it is possible to understand the measured branching ratios and determined the sizes and signs of nonfactorized amplitudes required.Comment: 15 pages, Late

De Novo Protein Structure Modeling from Cryoem Data Through a Dynamic Programming Algorithm in the Secondary Structure Topology Graph

Proteins are the molecules carry out the vital functions and make more than the half of dry weight in every cell. Protein in nature folds into a unique and energetically favorable 3-Dimensional (3-D) structure which is critical and unique to its biological function. In contrast to other methods for protein structure determination, Electron Cryorricroscopy (CryoEM) is able to produce volumetric maps of proteins that are poorly soluble, large and hard to crystallize. Furthermore, it studies the proteins in their native environment. Unfortunately, the volumetric maps generated by current advances in CryoEM technique produces protein maps at medium resolution about (~5 to 10Å) in which it is hard to determine the atomic-structure of the protein. However, the resolution of the volumetric maps is improving steadily, and recent works could obtain atomic models at higher resolutions (~3Å). De novo protein modeling is the process of building the structure of the protein using its CryoEM volumetric map. Thereupon, the volumetric maps at medium resolution generated by CryoEM technique proposed a new challenge. At the medium resolution, the location and orientation of secondary structure elements (SSE) can be visually and computationally identified. However, the order and direction (called protein topology) of the SSEs detected from the CryoEM volumetric map are not visible. In order to determine the protein structure, the topology of the SSEs has to be figured out and then the backbone can be built. Consequently, the topology problem has become a bottle neck for protein modeling using CryoEM In this dissertation, we focus to establish an effective computational framework to derive the atomic structure of a protein from the medium resolution CryoEM volumetric maps. This framework includes a topology graph component to rank effectively the topologies of the SSEs and a model building component. In order to generate the small subset of candidate topologies, the problem is translated into a layered graph representation. We developed a dynamic programming algorithm (TopoDP) for the new representation to overcome the problem of large search space. Our approach shows the improved accuracy, speed and memory use when compared with existing methods. However, the generating of such set was infeasible using a brute force method. Therefore, the topology graph component effectively reduces the topological space using the geometrical features of the secondary structures through a constrained K-shortest paths method in our layered graph. The model building component involves the bending of a helix and the loop construction using skeleton of the volumetric map. The forward-backward CCD is applied to bend the helices and model the loops