Real-time decoding of question-and-answer speech dialogue using human cortical activity.

Natural communication often occurs in dialogue, differentially engaging auditory and sensorimotor brain regions during listening and speaking. However, previous attempts to decode speech directly from the human brain typically consider listening or speaking tasks in isolation. Here, human participants listened to questions and responded aloud with answers while we used high-density electrocorticography (ECoG) recordings to detect when they heard or said an utterance and to then decode the utterance's identity. Because certain answers were only plausible responses to certain questions, we could dynamically update the prior probabilities of each answer using the decoded question likelihoods as context. We decode produced and perceived utterances with accuracy rates as high as 61% and 76%, respectively (chance is 7% and 20%). Contextual integration of decoded question likelihoods significantly improves answer decoding. These results demonstrate real-time decoding of speech in an interactive, conversational setting, which has important implications for patients who are unable to communicate

An experimental study of tip shape effects on the flutter of aft-swept, flat-plate wings

The effects of tip chord orientation on wing flutter are investigated experimentally using six cantilever-mounted, flat-plate wing models. Experimentally determined flutter characteristics of the six models are presented covering both the subsonic and transonic Mach number ranges. While all models have a 60 degree leading edge sweep, a 40.97 degree trailing edge sweep, and a root chord of 34.75 inches, they are subdivided into two series characterized by a higher aspect ratio and a lower aspect ratio. Each series is made up of three models with tip chord orientations which are parallel to the free-stream flow, perpendicular to the model mid-chord line, and perpendicular to the free-stream flow. Although planform characteristics within each series of models are held constant, structural characteristics such as mode shapes and natural frequencies are allowed to vary

Influence of Compactive Efforts on Compacted Foundry Sand Treated With Cement Kiln Dust

Laboratory tests were carried out on foundry sand treated with up to 12% cement kiln dust (CKD) by dry weight of soil to determine its suitability for use as road pavement material. Specimens were  compacted at the energy levels of Standard Proctor (BSL), West African standard (WAS) and British standard heavy (BSH). The foundry sand utilized in this study is classified as A-2(0) or SM using the America Association of Highway and Transportation Officials (AASHTO) and the Unified Soil Classification System (USCS), respectively. The 7day unconfined compressive strength (UCS) values recorded for the natural soil at BSL, WAS and BSH  compactive efforts record values of 165, 316 and 344 kN/m2 respectively, while peak values of 416, 378 and 444 kN/m2 were recorded at 8 % CKD, 6 % CKD  and 6 % CKD treatments  of foundry sand, respectively. None of the Specimens attained the UCS value of 1710 kN/m2 conventionally used as criterion for adequate cement stabilization. California bearing ratio values recorded for the untreated foundry sand at BSL, WAS and BSH  compactive efforts are 4, 6 and 8%, respectively. While peak California bearing ratio values of 15, 20 and 52% were recorded at 12% CKD treatments for BSL, WAS and BSH compactive effort respectively. The CBR values of 20 and 52% at treatment level of 8% CKD for WAS and BSH compactive effort satisfy the recommended minimum CBR value of 20-30% when  compacted at optimum moisture content  and 100% West African standards for sub-base material. The durability of specimens determined by immersion in water failed to produce an acceptable loss in strength value of less than 20% as specified for tropical soils.   Keywords: Cement Kiln Dust, Compacted Durability, California bearing ratio, Unconfined Compressive strength

Temperature dependence of the interlayer magnetoresistance of quasi-one-dimensional Fermi liquids at the magic angles

The interlayer magnetoresistance of a quasi-one-dimensional Fermi liquid is considered for the case of a magnetic field that is rotated within the plane perpendicular to the most-conducting direction. Within semi-classical transport theory dips in the magnetoresistance occur at integer amgic angles only when the electronic dispersion parallel to the chains is nonlinear. If the field direction is fixed at one of the magic angles and the temperature is varied the resulting variation of the scattering rate can lead to a non-monotonic variation of the interlayer magnetoresistance with temperature. Although the model considered here gives a good description of some of the properties of the Bechgaard salts, (TMTSF)2PF6 for pressures less than 8kbar and (TMTSF)2ClO4 it gives a poor description of their properties when the field is parallel to the layers and of the intralayer transport.Comment: 10pages, RevTeX + epsf, 3 figure

Transonic shock-induced dynamics of a flexible wing with a thick circular-arc airfoil

Transonic shock boundary layer oscillations occur on rigid models over a small range of Mach numbers on thick circular-arc airfoils. Extensive tests and analyses of this phenomena have been made in the past but essentially all of them were for rigid models. A simple flexible wing model with an 18 pct. circular arc airfoil was constructed and tested in the Langley Transonic Dynamics Tunnel to study the dynamic characteristics that a wing might have under these circumstances. In the region of shock boundary layer oscillations, buffeting of the first bending mode was obtained. This mode was well separated in frequency from the shock boundary layer oscillations. A limit cycle oscillation was also measured in a third bending like mode, involving wind vertical bending and splitter plate motion, which was in the frequency range of the shock boundary layer oscillations. Several model configurations were tested, and a few potential fixes were investigated

Experimental flutter boundaries with unsteady pressure distributions for the NACA 0012 Benchmark Model

The Structural Dynamics Div. at NASA-Langley has started a wind tunnel activity referred to as the Benchmark Models Program. The objective is to acquire test data that will be useful for developing and evaluating aeroelastic type Computational Fluid Dynamics codes currently in use or under development. The progress is described which was achieved in testing the first model in the Benchmark Models Program. Experimental flutter boundaries are presented for a rigid semispan model (NACA 0012 airfoil section) mounted on a flexible mount system. Also, steady and unsteady pressure measurements taken at the flutter condition are presented. The pressure data were acquired over the entire model chord located at the 60 pct. span station

Oil price shocks and fiscal policy management: Implications for Nigerian economic planning (1980-2009)

High Oil price fluctuations have been a common feature in Nigeria and these have considerably constituted a major source of fiscal policy disturbance to the Nigerian economy as well as the economies of other oil producing countries of the world. The over-reliance on oil production for income generation combined with local undiversified revenue and export bases is an issue for concern. This has policy implications for economic policy and in particular fiscal policy management. The motivation for this study is to examine the effect of oil price shock on fiscal policy in the country. Using structural vector autoregression (SVAR) methodology, the effects of crude oil price fluctuations on two major key fiscal policy variables (government expenditure (GEXP) and government revenue (GREV)), money supply (MS2) and GDP were examined. The results showed that oil prices have significant effect on fiscal policy in Nigeria within the study period of 1980: 1 to 2009: 4. The study also revealed that oil price shock affects GREV and GDP first before reflecting on fiscal expenditure. The study suggests strongly that diversification of the economy is necessary in order to minimize the consequences of oil price fluctuations on government revenue, by implication government expenditure planning in the country