Applications of dynamic diffuse signal processing in sound reinforcement and reproduction.

Electroacoustic systems are subject to position-dependent frequency responses due to coherent interference between multiple sources and/or early reflections. Diffuse signal processing (DiSP) provides a mechanism for signal decorrelation to potentially alleviate this well-known issue in sound reinforcement and reproduction applications. Previous testing has indicated that DiSP provides reduced low-frequency spatial variance across wide audience areas, but in closed acoustic spaces is less effective due to coherent early reflections. In this paper, dynamic implementation of DiSP is examined, whereby the decorrelation algorithm varies over time, thus allowing for decorrelation between surface reflections and direct sounds. Potential applications of dynamic DiSP are explored in the context of sound reinforcement (subwoofers, stage monitoring) and sound reproduction (small-room low-frequency control, loudspeaker crossovers), with preliminary experimental results presented.N/

Foreword: Sacred Violence: Religion and Terrorism

Forward to the Sacred Violence: Religion and Terrorism, Cleveland, OH, 200

Foreword: Sacred Violence: Religion and Terrorism

Forward to the Scared Violence: Religion and Terrorism, Cleveland, OH, 200

Defining true propagation patterns of underwater noise produced by stationary vessels

The study of underwater vessel noise over the past sixty years has predominantly focused upon the increase in ambient noise caused by the propulsion mechanisms of large commercial vessels. Studies have identified that the continuous rise of ambient noise levels in open waters is linked to the increase in size and strength of anthropogenic sound sources. Few studies have investigated the noise contribution of smaller vessels or ambient noise levels present in coastal and in-shore waters. This study aimed to identify the level of noise common to non-commercial harbors by studying the noise emissions of a diesel generator on board a 70m long sailing vessel. Propagation patterns revealed an unconventional shape (specific to the precise location of the noise source on board the vessel), unlike those of standard geometric spreading models, as typically assumed when predicting vessel noise emission. Harbor attributes (including water depth, ground sediment and structural material components) caused for altered level and frequency characteristics of the recorded underwater noise, and were correlated to the sound measurements made. The measurements (taken in eight harbors around Northern Europe) were statistically analyzed to identify the primary factors influencing near-field sound propagation around a stationary vessel

Prospecting Period Measurements with LSST - Low Mass X-ray Binaries as a Test Case

The Large Synoptic Survey Telescope (LSST) will provide for unbiased sampling of variability properties of objects with $r$ mag $<$ 24. This should allow for those objects whose variations reveal their orbital periods ($P_{orb}$), such as low mass X-ray binaries (LMXBs) and related objects, to be examined in much greater detail and with uniform systematic sampling. However, the baseline LSST observing strategy has temporal sampling that is not optimised for such work in the Galaxy. Here we assess four candidate observing strategies for measurement of $P_{orb}$ in the range 10 minutes to 50 days. We simulate multi-filter quiescent LMXB lightcurves including ellipsoidal modulation and stochastic flaring, and then sample these using LSST's operations simulator (OpSim) over the (mag, $P_{orb}$) parameter space, and over five sightlines sampling a range of possible reddening values. The percentage of simulated parameter space with correctly returned periods ranges from $\sim$23 %, for the current baseline strategy, to $\sim$70 % for the two simulated specialist strategies. Convolving these results with a $P_{orb}$ distribution, a modelled Galactic spatial distribution and reddening maps, we conservatively estimate that the most recent version of the LSST baseline strategy will allow $P_{orb}$ determination for $\sim$18 % of the Milky Way's LMXB population, whereas strategies that do not reduce observations of the Galactic Plane can improve this dramatically to $\sim$32 %. This increase would allow characterisation of the full binary population by breaking degeneracies between suggested $P_{orb}$ distributions in the literature. Our results can be used in the ongoing assessment of the effectiveness of various potential cadencing strategies.Comment: Replacement after addressing minor corrections from the referee - mainly improvements in clarificatio

Dynamic diffuse signal processing for sound reinforcement and reproduction.

High inter-channel coherence between signals emitted from multiple loudspeakers can cause undesirable acoustic and psychoacoustic effects. Examples include position-dependent low-frequency magnitude response variation, where comb-filtering leads to the attenuation of certain frequencies dependent on path length differences between multiple coherent sources, lack of apparent source width in multi-channel reproduction and lack of externalization in headphone reproduction. This work examines a time-variant, real-time decorrelation algorithm for the reduction of coherence between sources as well as between direct sound and early reflections, with a focus on minimization of low-frequency magnitude response variation. The algorithm is applicable to a wide range of sound reinforcement and reproduction applications, including those requiring full-band decorrelation. Key variables which control the balance between decorrelation and processing artifacts such as transient smearing are described and evaluated using a MUSHRA test. Variable values which render the processing transparent whilst still providing decorrelation are discussed. Additionally, the benefit of transient preservation is investigated and is shown to increase transparency.N/

Guidelines for Community‐Based Partners for Reviewing Research Grant Applications: Lessons from the Michigan Institute for Clinical and Health Research (MICHR) Community Engagement Research Core (CERC)

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102046/1/cts12126.pd

Effects of intersegmental transfers on target location by proteins

We study a model for a protein searching for a target, using facilitated diffusion, on a DNA molecule confined in a finite volume. The model includes three distinct pathways for facilitated diffusion: (a) sliding - in which the protein diffuses along the contour of the DNA (b) jumping - where the protein travels between two sites along the DNA by three-dimensional diffusion, and finally (c) intersegmental transfer - which allows the protein to move from one site to another by transiently binding both at the same time. The typical search time is calculated using scaling arguments which are verified numerically. Our results suggest that the inclusion of intersegmental transfer (i) decreases the search time considerably (ii) makes the search time much more robust to variations in the parameters of the model and (iii) that the optimal search time occurs in a regime very different than that found for models which ignore intersegmental transfers. The behavior we find is rich and shows surprising dependencies, for example, on the DNA length.Comment: 40 pages, 14 figure

Classes of fast and specific search mechanisms for proteins on DNA

Problems of search and recognition appear over different scales in biological systems. In this review we focus on the challenges posed by interactions between proteins, in particular transcription factors, and DNA and possible mechanisms which allow for a fast and selective target location. Initially we argue that DNA-binding proteins can be classified, broadly, into three distinct classes which we illustrate using experimental data. Each class calls for a different search process and we discuss the possible application of different search mechanisms proposed over the years to each class. The main thrust of this review is a new mechanism which is based on barrier discrimination. We introduce the model and analyze in detail its consequences. It is shown that this mechanism applies to all classes of transcription factors and can lead to a fast and specific search. Moreover, it is shown that the mechanism has interesting transient features which allow for stability at the target despite rapid binding and unbinding of the transcription factor from the target.Comment: 65 pages, 23 figure