A Physically-Constrained Source Model For FDTD Acoustic Simulation

The Finite Difference Time Domain (FDTD) method is becoming increasingly popular for room acoustics simulation. Yet, the literature on grid excitation methods is relatively sparse, and source functions are traditionally implemented in a hard or additive form
using arbitrarily-shaped functions which do not necessarily obey the physical laws of sound generation. In this paper we formulate
a source function based on a small pulsating sphere model. A physically plausible method to inject a source signal into the grid
is derived from first principles, resulting in a source with a near-flat spectrum that does not scatter incoming waves. In the final
discrete-time formulation, the source signal is the result of passing a Gaussian pulse through a digital filter simulating the dynamics of the pulsating sphere, hence facilitating a physically correct means to design source functions that generate a prescribed sound field.

RNA interference targeting cathepsin B of the carcinogenic liver fluke, Opisthorchis viverrini

Functional genomics have not been reported for Opisthorchis viverrini or the related fish-borne fluke, Clonorchis sinensis. Here we describe the introduction by square wave electroporation of Cy3-labeled small RNA into adult O. viverrini worms. Adult flukes were subjected to square wave electroporation employing a single pulse for 20 ms of 125V in the presence of 50 µg/ml of Cy3-siRNA. The parasites tolerated this manipulation and, at 24 and 48 h after electroporation, fluorescence from the Cy3-siRNA was evident throughout the parenchyma of the worms, with strong fluorescence evident in the guts and reproductive organs of the adult worms. Second, other worms were treated using the same electroporation settings with double stranded RNA targeting an endogenous papain-like cysteine protease, cathepsin B. This manipulation resulted in a significant reduction in specific mRNA levels encoding cathepsin B, and a significant reduction in cathepsin B activity against the diagnostic peptide, Z-Arg-Arg-AMC. This appears to be the first report of introduction of reporter genes into O. viverrini and the first report of experimental RNA interference (RNAi) in this fluke. The findings indicated the presence of an intact RNAi pathway in these parasites which, in turn, provides an opportunity to probe gene functions in this neglected tropical disease pathogen.

Acoustic Interculturalism: Listening to Performance

Acoustic Interculturalism is a study of the soundscapes of intercultural performance through the examination of sound's performativity. Employing an interdisciplinary approach, the book examines an akoumenological reception of sound to postulate the need for an acoustic knowing – an awareness of how sound shapes the intercultural experience.

Every Situation has its Rhythm: Acoustic Mimesis and Sonic Exoticism in Tambours Sur La Digue.

This article examines the soundscapes of Ariane Mnouchkine’s Tambours Sur La Digue and explores the concept of acoustic mimesis located in the performance as a dramaturgical strategy to create, aurally, an imagined Far East. In Tambours, mimesis is the performative principle exemplified by the presentation of the mise en scène, and most distinctly Mnouckine’s decision to adapt the Japanese performance tradition of Bunraku through a process of 'reversed' mimicry (in which human bodies simulate the wooden marionettes of the Japanese style). Mimesis pervades the acoustemologies of the performance as it is heard in the extracted sounds, styles, and rhythms of Asian musical modes and movements that consequently become dislocated from context; the sounds become imitated, iconicised and exoticised as sonic signatures as they reify the Orientalist spectacle. The 'oriental' soundscape, reverberating with exotic overtones, becomes the means by which the production creates an imaginary Orient – one in which the Orient Other is silenced, and is resounded only through the musical sensibilities of the Occidental Self.

If Music Be the Food of Love:An Acoustic ‘Fourth World’ in Ong Keng Sen’s Awaking”

Staged as an attempt to ‘bring together Shakespeare’s plays and Tang Xian Zu’s classical Kunqu opera, The Peony Pavilion,’ (Ong, Programme Notes) Awaking stands as Singapore Director Ong Keng Sen’s most recent and prominent attempt at engaging issues of the intercultural through music and sound. While Ong’s previous intercultural projects sought to explore the politics of intercultural performance through the exchange, layering, confrontation and inter-mixing of Asian performance modes as visual aesthetics, Awaking is a performance at the borders of theatrical and musical conventions, as it features the music and musicians as central performative devices of staging the intercultural. Northern Kunqu opera, Chinese classical music and Elizabethan folk tunes from Shakespeare’s plays were re-moved, re-contextualised, and juxtaposed to explore ‘differing yet connected philosophies on love, death, and the afterlife’ (Awaking, Publicity). These humanist and ‘universal’ themes found expression in the ‘universal’ language of music. Through a study of the musicalities and sonic expressions of Awaking, the paper seeks to explore the implications of such cultural-musical juxtapositions. The paper engages, specifically, with the problematics and possibilities of music as a ‘universal language’ as implied by Ong’s concordance of Eastern and Western sounds in the final act. It further considers the politics of an intercultural soundscape and the acoustemologies of such an intercultural approach.

MTERF1 Binds mtDNA to Prevent Transcriptional Interference at the Light-Strand Promoter but Is Dispensable for rRNA Gene Transcription Regulation

Mitochondrial transcription termination factor 1, MTERF1, has been reported to couple rRNA gene transcription initiation with termination and is therefore thought to be a key regulator of mammalian mitochondrial ribosome biogenesis. The prevailing model is based on a series of observations published over the last two decades, but no in vivo evidence exists to show that MTERF1 regulates transcription of the heavy-strand region of mtDNA containing the rRNA genes. Here, we demonstrate that knockout of Mterf1 in mice has no effect on mitochondrial rRNA levels or mitochondrial translation. Instead, loss of Mterf1 influences transcription initiation at the light-strand promoter, resulting in a decrease of de novo transcription manifested as reduced 7S RNA levels. Based on these observations, we suggest that MTERF1 does not regulate heavy-strand transcription, but rather acts to block transcription on the opposite strand of mtDNA to prevent transcription interference at the light-strand promoter.

Characterization of Inter-Body Interference in Context Aware Body Area Networking (CABAN)

The characterization and understanding of body to body communication channels is a pivotal step in the development of emerging wireless applications such as ad-hoc personnel localisation and context aware body area networks (CABAN). The latter is a recent innovation where the inherent mobility of body area networks can be used to improve the coexistence of multiple co-located BAN users. Rather than simply accepting reductions in communication performance, sensed changes in inter-network co-channel interference levels may facilitate intelligent inter-networking; for example merging or splitting with other BANs that remain in the same domain. This paper investigates the inter-body interference using controlled measurements of the full mesh interconnectivity between two ambulatory BANs operating in the same environment at 2.45 GHz. Each of the twelve network nodes reported received signal strength to allow for the creation of carrier to interference ratio time series with an overall entire mesh sampling period of 54 ms. The results indicate that even with two mobile networks, it is possible to identify the onset of co-channel interference as the BAN users move towards each other and, similarly, the transition to more favourable physical layer channel conditions as they move apart. © 2011 IEEE.

Nonlinear dust-acoustic solitary waves in strongly coupled dusty plasmas

Dust-acoustic waves are investigated in a three-component plasma consisting of strongly coupled dust particles and Maxwellian electrons and ions. A fluid model approach is used, with the effects of strong coupling being accounted for by an effective electrostatic "pressure" which is a function of the dust number density and the electrostatic potential. Both linear and weakly nonlinear cases are considered by derivation and analysis of the linear dispersion relation and the Korteweg-de Vries equation, respectively. In contrast to previous studies using this model, this paper presents the results arising from an expansion of the dynamical form of the electrostatic pressure, accounting for the variations in its value in the vicinity of the wave. DOI: 10.1103/PhysRevE.86.066404

Strong electrostatic interaction effect on modulational stability of dust acoustic waves

The modulational instability of dust-acoustic waves is investigated, relying on a recently proposed model for strong electrostatic interactions between the highly charged dust particles. The resulting effect on the occurrence (threshold, growth rate) of modulational instability is investigated. Our results can in principle be tested experimentally.

Thermomechanical analyses of ultrasonic welding process using thermal and acoustic softening effects

Ultrasonic welding process is a rapid manufacturing process used to weld thin layers of metal at low temperatures and low energy consumption. Experimental results have shown that ultrasonic welding is a combination of both surface (friction) and volume (plasticity) softening effects. In the presented work, a very first attempt has been made to simulate the ultrasonic welding of metals by taking into account both of these effects (surface and volume). A phenomenological material model has been proposed which incorporates these two effects (i.e. surface and volume). The thermal softening due to friction and ultrasonic (acoustic) softening has been included in the proposed material model. For surface effects a friction law with variable coefficient of friction dependent upon contact pressure, slip, temperature and number of cycles has been derived from experimental friction tests. Thermomechanical analyses of ultrasonic welding of aluminium alloy have been performed. The effects of ultrasonic welding process parameters, such as applied load, amplitude of ultrasonic vibration, and velocity of welding sonotrode on the friction work at the weld interface are being analyzed. The change in the friction work at the weld interface has been explained on the basis of softening (thermal and acoustic) of the specimen during the ultrasonic welding process. In the end, a comparison between experimental and simulated results has been presented showing a good agreement. © 2008 Elsevier Ltd. All rights reserved.

Rapid formation of robust auditory memories: Insights from noise

Before a natural sound can be recognized, an auditory signature of its source must be learned through experience. Here we used random waveforms to probe the formation of new memories for arbitrary complex sounds. A behavioral measure was designed, based on the detection of repetitions embedded in noises up to 4 s long. Unbeknownst to listeners, some noise samples reoccurred randomly throughout an experimental block. Results showed that repeated exposure induced learning for otherwise totally unpredictable and meaningless sounds. The learning was unsupervised and resilient to interference from other task-relevant noises. When memories were formed, they emerged rapidly, performance became abruptly near-perfect, and multiple noises were remembered for several weeks. The acoustic transformations to which recall was tolerant suggest that the learned features were local in time. We propose that rapid sensory plasticity could explain how the auditory brain creates useful memories from the ever-changing, but sometimes repeating, acoustical world. © 2010 Elsevier Inc.