The coupling of a hearing aid loudspeaker membrane to visco-thermal air layers

Hearing aids and their components are becoming smaller. This presents new problems for the acoustical components, such as the loudspeaker. A circular membrane of a hearing aid loudspeaker is modeled in this paper. Neglecting air influences, the membrane and its suspension behave as a mass spring system. However, under operating conditions, thin layers of air on both sides of the membrane influence its behavior. Air can enter and leave these layers at certain locations on the circular edge of the layer. Since these air layers are thin, visco-thermal effects may have to be taken into account. Therefore, the air layers are not modeled by the wave equation, but by the low reduced frequency model that takes these visco-thermal effects into account. The equations of this model are solved in a polar coordinate system, using a wave-based method. The other acoustical parts of the hearing aid loudspeaker, and the membrane itself are modeled by simple lumped models. The emphasis in this paper is on the coupling of the viscothermal air layer model to the mechanical model of the membrane. Coupling of the air layer to other acoustical parts by using an impedance as boundary condition for the layer model, is also described. The resulting model is verified by experiments. The model and the measurements match reasonably well, considering the level of approximation with lumped parts

A literature review of trust and reputation management in communicable disease public health

Executive Summary: A literature review of trust and reputation management by and for public health organisations involved in communicable disease control was conducted by the Institute for Social Marketing. The Institute is a joint research initiative of the University of Stirling and the Open University in the UK. The review examined the international English-language literature published during the period 2005-2010, drawn from a range of communication sub-disciplines. A glossary of the sub-disciplines is provided in the appendix. The evidence base was found to be in an emergent phase and is therefore somewhat limited, although largely consistent. Elements of good practice identified included the need for long-term and proactive planning of trust and reputation management; strong media relations skills; proactive relationship building with key stakeholders; integration with technical disease prevention and control functions; and enhanced commitment to transparency and two-way dialogues. A focus on crisis communication, mass (undifferentiated) communication and communication to support technical functions was apparent in the literature. A limited understanding of the role and nature of risk communication; the benefits of adopting a strategic, rather than reactive approach to trust and reputation management and the potential benefits of full integration with immediate and long-term public health goals was also apparent. Recommendations for future research and development of good practice are evaluations specifically focused on the impact of public health activities on trust and reputation; adopting a strategic approach to trust and reputation planning which coordinates the full range of communication functions and objectives; plus organisational capacity building in communication functions such as risk communication, environmental scanning and mass media relations

Mass anti-austerity protests in Portugal are emerging out of social movements which have been fighting against precarious conditions in the labour market

Tiago Carvalho, Nuno de Almeida Alves, David Cairns and Ana Alexandre report on recent mass street protests in Portugal against the government’s painful austerity programme. These demonstrations, with the most recent instance estimated to encompass one million people across 40 towns and cities, have emerged as a consequence of longer standing social movements which have sought to overturn a broader trend within Portugese society towards the growth of precarious working conditions, where low pay is coupled with little employment protection

The COVID-19 pandemic and international students: Consequences for researchers, stakeholders and policymakers in the mobility field

Since the early months of 2020, COVID-19 has had a profound impact on societies, transforming social, economic and political life throughout the European Union. This resulted in dramatic change in a central aspect of life for many Europeans: the freedom to circulate between countries for non-essential purposes, including tertiary education. This loss has created problems for EU citizens and others from third-party countries, who have found themselves cut off from essential support or the means to return home in a safe and timely manner. In this chapter, we take a look at this situation, with our research questions considering some of the most prominent impacts of the pandemic on internationalised learning for both intra-EU exchange students and extra-EU educational migrants. To illustrate the emerging challenges, we have conducted research with international students in Portugal during the initial months of the public health emergency, from which we were able to identify issues that may be of concern to researchers, stakeholders and policymakers in the mobility field.info:eu-repo/semantics/publishedVersio

The prevalence and origin of exoprotease-producing cells in the <em>Bacillus subtilis </em>biofilm

Biofilm formation by the Gram-positive bacterium Bacillus subtilis is tightly controlled at the level of transcription. The biofilm contains specialized cell types that arise from controlled differentiation of the resident isogenic bacteria. DegU is a response regulator that controls several social behaviours exhibited by B. subtilis including swarming motility, biofilm formation and extracellular protease (exoprotease) production. Here, for the first time, we examine the prevalence and origin of exoprotease-producing cells within the biofilm. This was accomplished using single-cell analysis techniques including flow cytometry and fluorescence microscopy. We established that the number of exoprotease-producing cells increases as the biofilm matures. This is reflected by both an increase at the level of transcription and an increase in exoprotease activity over time. We go on to demonstrate that exoprotease-producing cells arise from more than one cell type, namely matrix-producing and non-matrix-producing cells. In toto these findings allow us to add exoprotease-producing cells to the list of specialized cell types that are derived during B. subtilis biofilm formation and furthermore the data highlight the plasticity in the origin of differentiated cells

De-risking strategy: Longevity spread buy-in

The paper proposes a demographic de-risking strategy for a pension provider, to deal with the future uncertainty in longevity over a long time horizon. The innovative idea of a longevity spread buy-in is presented. The formulae for calculating the buy-in premium are proposed in the case of pension plans. The proposal directly impacts the pension provider’s risk management systems and hence can be an important part of the overall approach to risk management. The numerical results, developed under specified stochastic hypotheses for the dynamics of the underlying financial and demographic processes, show how the proposal of the paper can be practically implemented

Ponderomotive and resonant effects in the acceleration of particles by electromagnetic modes

Funding: U.K. Science and Engineering Research Council under Grant No. EP/N028694/1 (R.A.C.).In the present analysis, we study the dynamics of charged particles under the action of slowly modulated electromagnetic carrier waves. With the use of a high-frequency laser mode along with a modulated static magnetic wiggler, we show that the ensuing total field effectively acts as a slowly modulated high-frequency beat-wave field typical of inverse free-electron laser schemes. This effective resulting field is capable of accelerating particles in much the same way as space-charge wake fields do in plasma accelerators, with the advantage of being more stable than plasma related methods. Acceleration occurs as particles transition from ponderomotive to resonant regimes, so we develop the ponder- omotive formalism needed to examine this problem. The ponderomotive formalism includes terms that, although not discussed in the usual applications of the approximation, are nevertheless of crucial importance in the vicinity of resonant capture. The role of these terms is also briefly discussed in the context of generic laser-plasma interactions.PostprintPeer reviewe

The competing chemical and physical effects of transient fuel enrichment on heavy knock in an optical spark ignition engine

The work was concerned with improving understanding of the chemical and physical trade-offs when employing transient over-fuelling to control auto-ignition in gasoline spark ignition engines under knock intensities not usually tolerated in optical engines. The single cylinder engine used included full bore overhead optical access capable of withstanding unusually high in-cylinder pressures. Heavy knock was deliberately induced by adopting inlet air heating and a primary reference fuel blend of reduced octane rating. High-speed chemiluminescence imaging and simultaneous in-cylinder pressure data measurement were used to evaluate the combustion events. Under normal operation the engine was operated under port fuel injection with a stoichiometric air-fuel mixture. Multiple centred auto-ignition events were regularly observed, with knock intensities of up to ~30bar. Additional excess fuel was then introduced directly into the end-gas in short transient bursts. As the mass of excess fuel was progressively increased a trade-off was apparent, with knock intensity first increasing by up to 65% before lower unburned gas temperatures suppressed knock under extremely rich conditions. This trade-off is not usually observed during conventional low intensity knock suppression via over-fuelling and has been associated with the competing effects of reducing auto-ignition delay time and charge cooling/ratio of specific heats. Overall, the results demonstrate the risks in employing excess fuel to suppress knock deep within a heavy knocking combustion regime (potentially including a Super-Knock regime)

Cancer's sweet tooth for serine

Exemplified by the cancer cell's preference for glycolysis (the Warburg effect), altered metabolism has taken centerstage as an emerging hallmark of cancer. Charting the landscape of cancer metabolic addictions should reveal new avenues for therapeutic attack. Two recent studies found subsets of human melanoma and breast cancers to have high levels of phosphoglycerate dehydrogenase (PHGDH), a key enzyme for serine biosynthesis, and these cancer cells are dependent on PHGDH for their growth and survival. Tumors may thus harbor distinct metabolic alterations to support their malignancy, and targeting enzymes such as PHGDH might prove a viable therapeutic strategy in this scenario

DNA compaction by the higher-order assembly of PRH/Hex homeodomain protein oligomers

Protein self-organization is essential for the establishment and maintenance of nuclear architecture and for the regulation of gene expression. We have shown previously that the Proline-Rich Homeodomain protein (PRH/Hex) self-assembles to form oligomeric complexes that bind to arrays of PRH binding sites with high affinity and specificity. We have also shown that many PRH target genes contain suitably spaced arrays of PRH sites that allow this protein to bind and regulate transcription. Here, we use analytical ultracentrifugation and electron microscopy to further characterize PRH oligomers. We use the same techniques to show that PRH oligomers bound to long DNA fragments self-associate to form highly ordered assemblies. Electron microscopy and linear dichroism reveal that PRH oligomers can form protein–DNA fibres and that PRH is able to compact DNA in the absence of other proteins. Finally, we show that DNA compaction is not sufficient for the repression of PRH target genes in cells. We conclude that DNA compaction is a consequence of the binding of large PRH oligomers to arrays of binding sites and that PRH is functionally and structurally related to the Lrp/AsnC family of proteins from bacteria and archaea, a group of proteins formerly thought to be without eukaryotic equivalents