A reduced-order-model-based equivalent circuit for piezoelectric micro-electro-mechanical-system loudspeakers modeling

Piezoelectric micro-electro-mechanical-system (MEMS) speakers are emerging as promising implementations of loudspeakers at the microscale, as they are able to meet the ever-increasing requirements for modern audio devices to become smaller, lighter, and integrable into digital systems. In this work, we propose a finite element model (FEM)-assisted lumped-parameters equivalent circuit for a fast and accurate modeling of these types of devices. The electro-mechanical parameters are derived from a pre-stressed FEM eigenfrequency analysis, to account for arbitrarily complex geometries and for the shift of the speaker resonance frequency due to an initial non-null pre-deflected configuration. The parameters of the acoustical circuit are instead computed through analytical formulas. The acoustic short-circuit between the speaker front and rear sides is taken into account through a proper air-gaps modeling. The very good matching in terms of radiated sound pressure level among the equivalent circuit predictions, FEM simulations, and experimental data proves the ability of the proposed method to accurately simulate the speaker performance. Moreover, due to its generality, it represents a versatile tool for designing piezoelectric MEMS speakers.

Assessing awareness and use of HIV self-testing kits after the introduction of a community-based HIV self-testing programme among men who have sex with men in Kenya

Men who have sex with men (MSM) bear a disproportionate burden of new HIV infections in Kenya, while experiencing discrimination, leading to suboptimal levels of HIV care. HIV self-testing (HIVST) is a tool to increase HIV screening and earlier diagnosis; however, questions remain regarding how best to scale-up HIVST to MSM in Kenya. The main objective of this study was to examine changes in knowledge and use of HIVST after implementation of a community-led HIVST project. Participants were MSM recruited from Kisumu, Mombasa, and Kiambu counties. Data were collected from two rounds (Round 1: 2019; Round 2: 2020) of serial cross-sectional integrated biological and behavioural assessments (IBBA), pre-, and post-project implementation. Two main outcomes were measured: 1) whether the respondent had ever heard of HIVST; and 2) whether they had ever used HIVST kits. Changes in outcomes between IBBA rounds were examined using modified multivariable Poisson regression models; adjusted prevalence ratios (aPR) and 95% confidence intervals (95% CI) are reported. A total of 2,328 respondents were included in main analyses. The proportion of respondents who had heard of HIVST increased from 75% in Round 1 to 94% in Round 2 (aPR: 1.2, 95% CI: 1.2-1.3), while those reporting using an HIVST kit increased from 20% to 53% (aPR: 2.3, 95% CI: 2.0-2.6). Higher levels of education and HIV programme awareness were associated with both outcomes. Awareness and use of HIVST kits increased after implementation of a community-led HIVST implementation project, demonstrating the importance of integration with existing community groups.

Understanding socio-sexual networks: critical consideration for HIVST intervention planning among men who have sex with men in Kenya

BACKGROUND

HIV self-testing (HIVST) has emerged as a way of reaching individuals who may be less likely to access testing, including men who have sex with men (MSM). Understanding the social networks of MSM is key to tailoring interventions, such as HIVST, for particular locations.

METHODS

We undertook a socio-sexual network study to characterize and identify patterns of connection among MSM and inform an HIVST intervention in three sites in Kenya. Community researchers in each site selected eight seeds to complete a demographic form and network surveys for 15 each of their sexual and social network members. Seeds recruited three respondents, including two regular service users and one MSM who was "unreached" by the program, who then each identified three respondents, resulting with data on 290 individuals.

RESULTS

Findings illustrate the interconnectedness of community-based organization (CBO) members and non-members. In networks where a majority of members had a CBO membership, members had better contacts with programs and were more likely to have accessed health services. Larger networks had more HIV testing and seeds with frequent testing had a positive influence on their network members also being tested frequently. HIVST was tried in very few networks. Almost all network members were willing to use HIVST.

CONCLUSION

Willingness to use HIVST was nearly universal and points to the importance of networks for reaching individuals not enrolled in programs. Network analysis can help in understanding which type of networks had higher testing and how network-based approaches can be useful to promote HIVST in certain contexts.

Experimental acoustic scene analysis using One-Eighth spherical fraction microphone array

This paper investigates the performance of one-eighth Spherical Fraction Microphone Array through experimental measurement to analyze acoustic scenes in one-eighth of space. The array geometry is designed to be placed in a room corner at the junction of three acoustically rigid walls. Two prototypes are built with 8 and 16 microphones, respectively. The sampling strategy is discussed and a spatial aliasing analysis is carried out both analytically and by numerical simulations. The array performances are evaluated through Spherical Fraction Beamforming (SFB). This approach is based on the decomposition of the acoustic pressure field in a rigid bounded domain. The localization angular error and Directivity Index criterion are evaluated for both arrays. In a first experiment, the arrays are mounted in an eighth of space built inside an anechoic room. The results are compared with simulation and show consistency. The theoretical limitations of SFB in a rigid bounded one-eighth of space are retrieved experimentally. These limitations are also observed in a real configuration: an office room. Further investigations on SFB are also conducted in the case of a virtual scene constructed with two sound sources.

HIV testing amid COVID-19: community efforts to reach men who have sex with men in three Kenyan counties

In comparison to European and American countries, Kenya has been less impacted by the COVID-19 pandemic in terms of reported cases and mortalities. However, everyday life has been dramatically affected by highly restrictive government-imposed measures such as stay-at-home curfews, prohibitions on mobility across national and county boundaries, and strict policing, especially of the urban poor, which has culminated in violence. This open letter highlights the effects of these measures on how three community-based organizations (CBOs) deliver HIV programs and services to highly stigmatized communities of men who have sex with men living in the counties of Kisumu, Kiambu and Mombasa. In particular, emphasis is placed on how HIV testing programs, which are supported by systematic peer outreach, are being disrupted at a time when global policymakers call for expanded HIV testing and treatment targets among key populations. While COVID 19 measures have greatly undermined local efforts to deliver health services to members and strengthen existing HIV testing programs, each of the three CBOs has taken innovative steps to adapt to the restrictions and to the COVID-19 pandemic itself. Although HIV testing in clinical spaces among those who were once regular and occasional program attendees dropped off noticeably in the early months of the COVID-19 lockdown, the program eventually began to rebound as outreach approaches shifted to virtual platforms and strategies. Importantly and unexpectedly, HIV self-testing kits proved to fill a major gap in clinic-based HIV testing at a time of crisis.

HIV testing amid COVID-19: community efforts to reach men who have sex with men in three Kenyan counties

In comparison to European and American countries, Kenya has been less impacted by the COVID-19 pandemic in terms of reported cases and mortalities. However, everyday life has been dramatically affected by highly restrictive government-imposed measures such as stay-at-home curfews, prohibitions on mobility across national and county boundaries, and strict policing, especially of the urban poor, which has culminated in violence. This open letter highlights the effects of these measures on how three community-based organizations (CBOs) deliver HIV programs and services to highly stigmatized communities of men who have sex with men living in the counties of Kisumu, Kiambu and Mombasa. In particular, emphasis is placed on how HIV testing programs, which are supported by systematic peer outreach, are being disrupted at a time when global policymakers call for expanded HIV testing and treatment targets among key populations. While COVID 19 measures have greatly undermined local efforts to deliver health services to members and strengthen existing HIV testing programs, each of the three CBOs has taken innovative steps to adapt to the restrictions and to the COVID-19 pandemic itself. Although HIV testing in clinical spaces among those who were once regular and occasional program attendees dropped off noticeably in the early months of the COVID-19 lockdown, the program eventually began to rebound as outreach approaches shifted to virtual platforms and strategies. Importantly and unexpectedly, HIV self-testing kits proved to fill a major gap in clinic-based HIV testing at a time of crisis.

HIV prevalence, testing and treatment among men who have sex with men through engagement in virtual sexual networks in Kenya: a cross-sectional bio-behavioural study

INTRODUCTION

In Kenya, men who have sex with men (MSM) are increasingly using virtual sites, including web-based apps, to meet sex partners. We examined HIV testing, HIV prevalence, awareness of HIV-positive status and linkage to antiretroviral therapy (ART), for HIV-positive MSM who solely met partners via physical sites (PMSM), compared with those who did so in virtual sites (either solely via virtual sites (VMSM), or via both virtual and physical sites (DMSM)).

METHODS

We conducted a cross-sectional bio-behavioural survey of 1200 MSM, 15 years and above, in three counties in Kenya between May and July 2019, using random sampling of physical and virtual sites. We classified participants as PMSM, DMSM and VMSM, based on where they met sex partners, and compared the following between groups using chi-square tests: (i) proportion tested; (ii) HIV prevalence and (iii) HIV care continuum among MSM living with HIV. We then performed multivariable logistic regression to measure independent associations between network engagement and HIV status.

RESULTS

177 (14.7%), 768 (64.0%) and 255 (21.2%), of participants were classified as PMSM, DMSM and VMSM respectively. 68.4%, 70.4% and 78.5% of PMSM, DMSM and VMSM, respectively, reported an HIV test in the previous six months. HIV prevalence was 8.5% (PMSM), 15.4% (DMSM) and 26.7% (VMSM), p < 0.001. Among those living with HIV, 46.7% (PMSM), 41.5% (DMSM) and 29.4% (VMSM) were diagnosed and aware of their status; and 40.0%, 35.6% and 26.5% were on antiretroviral treatment. After adjustment for other predictors, MSM engaged in virtual networks remained at a two to threefold higher risk of prevalent HIV: VMSM versus PMSM (adjusted odds ratio 3.88 (95% confidence interval (CI) 1.84 to 8.17) p < 0.001); DMSM versus PMSM (2.00 (95% CI 1.03 to 3.87), p = 0.040).

CONCLUSIONS

Engagement in virtual networks is associated with elevated HIV risk, irrespective of individual-level risk factors. Understanding the difference in characteristics among MSM-seeking partners in different sites will help HIV programmes to develop subpopulation-specific interventions.

Nosocomial outbreak due to a multiresistant strain of Pseudomonas aeruginosa P12: efficacy of cefepime-amikacin therapy and analysis of beta-lactam resistance

Over a 3-year period, 67 patients of the Hospital of Pau (Pau, France), including 64 patients hospitalized in the adult intensive care unit (ICU), were colonized and/or infected by strains of Pseudomonas aeruginosa P12, resistant to all potentially active antibiotics except colistin. Most patients were mechanically ventilated and presented respiratory tract infections. Since cefepime and amikacin were the least inactive antibiotics by MIC determination, all ICU patients were treated with this combination, and most of them benefited. Cefepime-amikacin was found highly synergistic in vitro. Ribotyping and arbitrary primer-PCR analysis confirmed the presence of a single clonal isolate. Isoelectrofocusing revealed that the epidemic strain produced large amounts of the chromosomal cephalosporinase and an additional enzyme with a pI of 5.7, corresponding to PSE-1, as demonstrated by PCR and sequencing. Outer membrane protein profiles on sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed the absence of a ca. 46-kDa protein, likely to be OprD, and increased production of two ca. 49- and 50-kDa proteins, consistent with the outer membrane components of the efflux systems, MexAB-OprM and MexEF-OprN. Thus, we report here a nosocomial outbreak due to multiresistant P. aeruginosa P12 exhibiting at least four mechanisms of beta-lactam resistance, i.e., production of the penicillinase PSE-1, overproduction of the chromosomal cephalosporinase, loss of OprD, and overexpression of efflux systems, associated with a better activity of cefepime than ceftazidime.

[Comparative in vitro activity of cefepime: multicenter study in Aquitaine]

Over a 6 month-period (1st January to 30th June 1995), the results of antibiotic susceptibility testing routinely performed for beta-lactams against enterobacteria, Pseudomonas aeruginosa, and Acinetobacter in 7 laboratory hospitals of Aquitaine, have been collected and divided in susceptibility profiles. A total of 9269 strains (7323 enterobacteria, 1667 P. aeruginosa, 279 Acinetobacter) have been examined. On the whole, cefepime (91,5%) and ceftazidime (91,7%) were the most active cephalosporins, followed by cefpirome (87,9%) and cefotaxime (80,4%); imipenem was the most active beta-lactam agent (97,4%). When the strains were divided according to their susceptibility profiles, the advantage of cefepime was shown to be related to its excellent activity against enterobacteria: all strains susceptible to cefotaxime and ceftazidime (CTX/CAZ-S) were susceptible to cefepime, as were most of the strains with an intermediate susceptibility or resistant to these drugs (CTX/CAZ-I/R, approximately 5% of the enterobacteria). The latter strains exhibited a phenotype corresponding either to the overproduction of their chromosomal cephalosporinase (approximately 20% of the species belonging to group 3) or to the synthesis of an extended spectrum beta-lactamase (19% of the strains of Klebsiella pneumoniae). Cefepime was active against 93% of the derepressed mutants of enterobacteria, including 3 imipenem resistant isolates of Enterobacter. CAZ-S strains of P. aeruginosa (84%) were usually susceptible to cefepime (80%), as were 6% of the CAZ-I/R strains. CAZ-S strains of A. baumannii (16.3%) were generally susceptible to cefepime (83%), as were 3.2% of the CAZ-I/R strains.

Value of influenza vaccine during an outbreak of influenza A in a nursing home, Pyrenees Atlantiques, France, November-December 1995

A public health officer of the Direction Departementale de l'Action Sanitaire et Sociale des Pyrenees Atlantiques in France was notified of an outbreak of acute respiratory illness among residents of a nursing home on 4 December, 1995. Over 50 of the 69 r