CABE : a cloud-based acoustic beamforming emulator for FPGA-based sound source localization

Microphone arrays are gaining in popularity thanks to the availability of low-cost microphones. Applications including sonar, binaural hearing aid devices, acoustic indoor localization techniques and speech recognition are proposed by several research groups and companies. In most of the available implementations, the microphones utilized are assumed to offer an ideal response in a given frequency domain. Several toolboxes and software can be used to obtain a theoretical response of a microphone array with a given beamforming algorithm. However, a tool facilitating the design of a microphone array taking into account the non-ideal characteristics could not be found. Moreover, generating packages facilitating the implementation on Field Programmable Gate Arrays has, to our knowledge, not been carried out yet. Visualizing the responses in 2D and 3D also poses an engineering challenge. To alleviate these shortcomings, a scalable Cloud-based Acoustic Beamforming Emulator (CABE) is proposed. The non-ideal characteristics of microphones are considered during the computations and results are validated with acoustic data captured from microphones. It is also possible to generate hardware description language packages containing delay tables facilitating the implementation of Delay-and-Sum beamformers in embedded hardware. Truncation error analysis can also be carried out for fixed-point signal processing. The effects of disabling a given group of microphones within the microphone array can also be calculated. Results and packages can be visualized with a dedicated client application. Users can create and configure several parameters of an emulation, including sound source placement, the shape of the microphone array and the required signal processing flow. Depending on the user configuration, 2D and 3D graphs showing the beamforming results, waterfall diagrams and performance metrics can be generated by the client application. The emulations are also validated with captured data from existing microphone arrays.</jats:p

Optimal Monetary Rules: The Case of Brazil

Within a dynamic programming approach we derive an optimal rule for the central bank to attain it's inflation targeting goals. The short-run nominal interest rate is used as an instrument to achieve monetary objectives. The model is tested for the Brazilian economy and compared with results found for other countries. Evidence for the estimated feedback interest rule for the Central Bank suggests that the cost of reducing inflation in an open economy is lower than that of a closed economy.

Black holes in asymptotically Lifshitz spacetimes with arbitrary critical exponent

Recently, a class of gravitational backgrounds in 3+1 dimensions have been proposed as holographic duals to a Lifshitz theory describing critical phenomena in 2+1 dimensions with critical exponent $z\geq 1$. We numerically explore black holes in these backgrounds for a range of values of $z$. We find drastically different behavior for $z>2$ and $z2$ ($z<2$) the Lifshitz fixed point is repulsive (attractive) when going to larger radial parameter $r$. For the repulsive $z>2$ backgrounds, we find a continuous family of black holes satisfying a finite energy condition. However, for $z<2$ we find that the finite energy condition is more restrictive, and we expect only a discrete set of black hole solutions, unless some unexpected cancellations occur. For all black holes, we plot temperature $T$ as a function of horizon radius $r_0$. For $z\lessapprox 1.761$ we find that this curve develops a negative slope for certain values of $r_0$ possibly indicating a thermodynamic instability.Comment: 23 pages, 6 figures, references corrected, graphs made readable in greyscal

Allosteric activation unveils protein-mass modulation of ATP phosphoribosyltransferase product release

Funding: This work was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) [Grant BB/M010996/1] via an EASTBIO Doctoral Training Partnership studentship to B.J.R.Heavy-isotope substitution into enzymes slows down bond vibrations and may alter transition-state barrier crossing probability if this is coupled to fast protein motions. ATP phosphoribosyltransferase from Acinetobacter baumannii is a multi-protein complex where the regulatory protein HisZ allosterically enhances catalysis by the catalytic protein HisGS. This is accompanied by a shift in rate-limiting step from chemistry to product release. Here we report that isotope-labelling of HisGS has no effect on the nonactivated reaction, which involves negative activation heat capacity, while HisZ-activated HisGS catalytic rate decreases in a strictly mass-dependent fashion across five different HisGS masses, at low temperatures. Surprisingly, the effect is not linked to the chemical step, but to fast motions governing product release in the activated enzyme. Disruption of a specific enzyme-product interaction abolishes the isotope effects. Results highlight how altered protein mass perturbs allosterically modulated thermal motions relevant to the catalytic cycle beyond the chemical step.Peer reviewe

Groundwater management in the state of Piauí (Brazil) on the climate change context

This article aims to evaluate the current state of groundwater management in the state of Piauí, considering the scenario of climate change and its adverse effects on aquifers. The analysis is based on the socioeconomic reality of the state, the availability and demand of groundwater resources, and the level of management and the possible impacts of climate change on the state. What is noticeable is that for the projected scenarios of climate change in the state, groundwater becomes a strategic source in mitigating the effects of climate change; however, the diagnosis produced shows that the state has already been using this resource too much, but without an efficient control of the public power. This combination tends toward a pessimistic view of both the state and groundwater in relation to climate change.O presente artigo tem o objetivo de avaliar o estado atual da gestão das águas subterrâneas no estado do Piauí considerando o cenário das mudanças climáticas e seus efeitos adversos sobre os aquíferos. A análise é feita a partir da realidade socioeconômica do estado, da disponibilidade e demanda dos recursos hídricos subterrâneos e do nível de gestão e os possíveis impactos das mudanças climáticas para o estado. O que se nota é que para os cenários projetados das mudanças climáticas no estado, as águas subterrâneas tornam-se uma fonte estratégica na amenização dos efeitos das mudanças climáticas, entretanto, o diagnóstico produzido mostra que o estado já vem utilizando esse recurso em demasia, mas sem um controle eficiente do poder público. Essa combinação tende para uma visão pessimista tanto para o estado quanto para as águas subterrâneas em relação às mudanças climáticas

Trifocal Relative Pose from Lines at Points and its Efficient Solution

We present a new minimal problem for relative pose estimation mixing point features with lines incident at points observed in three views and its efficient homotopy continuation solver. We demonstrate the generality of the approach by analyzing and solving an additional problem with mixed point and line correspondences in three views. The minimal problems include correspondences of (i) three points and one line and (ii) three points and two lines through two of the points which is reported and analyzed here for the first time. These are difficult to solve, as they have 216 and - as shown here - 312 solutions, but cover important practical situations when line and point features appear together, e.g., in urban scenes or when observing curves. We demonstrate that even such difficult problems can be solved robustly using a suitable homotopy continuation technique and we provide an implementation optimized for minimal problems that can be integrated into engineering applications. Our simulated and real experiments demonstrate our solvers in the camera geometry computation task in structure from motion. We show that new solvers allow for reconstructing challenging scenes where the standard two-view initialization of structure from motion fails.Comment: This material is based upon work supported by the National Science Foundation under Grant No. DMS-1439786 while most authors were in residence at Brown University's Institute for Computational and Experimental Research in Mathematics -- ICERM, in Providence, R