Zero refractive index in space-time acoustic metamaterials

New scientific investigations of artificially structured materials and experiments have exhibit wave manipulation to the extreme. In particular, zero refractive index metamaterials have been on the front line of wave physics research for their unique wave manipulation properties and application potentials. Remarkably, in such exotic materials, time-harmonic fields have infinite wavelength and do not exhibit any spatial variations in their phase distribution. This unique feature can be achieved by forcing a Dirac cone to the center of the Brillouin zone ( point), as previously predicted and experimentally demonstrated in time-invariant metamaterials by means of accidental degeneracy between three different modes. In this article, we propose a different approach that enables true conical dispersion at with twofold degeneracy, and generates zero index properties. We break time-reversal symmetry and exploit a space-time modulation scheme to demonstrate a time-Floquet acoustic metamaterial with zero refractive index. This behavior, predicted using stroboscopic analysis, is confirmed by fullwave finite elements simulations. Our results establish the relevance of space-time metamaterials as a novel reconfigurable platform for wave control

The Inequitable Burden of Infectious Diseases Among Remote-living Aboriginal and Torres Strait Islander Australians: A Product of History

Insufficient and poorly maintained housing and plumbing in many remote Australian Indigenous communities in Australia results in reduced capacity to maintain personal hygiene, contributing to infectious disease inequalities. Infections from Streptococcus pyogenes (Strep A) and sequalae are often noted to be the result of contextual poverty; a product of over 230 years of discriminatory practice that has excluded Indigenous people from the basic human rights of healthy, maintained housing afforded to most in the nation. The solutions for eliminating diseases of inequity among Australian Indigenous population are known, their success is historically documented, and yet they are to be comprehensively implemented in the remote Indigenous communities. This paper explores how decades of inequitable policy has permeated contemporary Australian Indigenous wellbeing with specific regards to infectious disease rates; a deviation from thousands of years with limited exposure to such illnesses

Scabies and impetigo in Timor-Leste: A school screening study in two districts

Introduction Scabies and impetigo are common and important skin conditions which are often neglected in developing countries. Limited data have been published on the prevalence of scabies and impetigo in Timor-Leste. Sequelae including cellulitis, bacteraemia, nephritis, acute rheumatic fever and rheumatic heart disease contribute significantly to the burden of disease. Methods School students were recruited from schools in Dili (urban) and Ermera (rural) in Timor-Leste for an epidemiological study in October 2016. A standard questionnaire was used to record demographics, anthropometry and skin examination results. Impetigo and scabies were diagnosed based on clinical examination of exposed surfaces, and clinical photographs were reviewed for correlation by an infectious diseases paediatrician. Prevalence of scabies and impetigo were calculated and binary risk factor associations were described using relative risks and 95% confidence intervals. Adjusted odds ratios were calculated using logistic regression multivariate analysis. Continuous variables were analysed for associations using the Mann-Whitney Rank Sum test. Results The study enrolled 1396 students; median age 11 years (interquartile range (IQR) 9-15). The prevalence of scabies was 22.4% (95% Cl 20.2-24.7%) and active impetigo 9.7% (95% Cl 8.3-11.4%); 68.2% of students had evidence of either active or healed impetigo. Students in Ermera were more likely than those in Dili to have scabies (prevalence 32.0% vs 5.2%, aOR 8.1 (95% Cl 5.2-12.4), p<0.01). There was no difference in the prevalence of active impetigo between urban and rural sites. More than a third of participants were moderately or severely underweight. Stunting was markedly more common in the rural district of Ermera. Conclusion Scabies and impetigo are common in Timor-Leste, with very high prevalence of scabies in the rural district of Ermera. Improvements in prevention and treatment are needed, with prioritised activities in the rural areas where prevalence is highesThe study was funded by East Timor Hearts Fund https://www.easttimorheartsfund.org. au. The study was also supported by Menzies School of Health Research (https://www.menzies. edu.au/) and Telethon Kids Institute (www. telethonkids.org.au). A donation of LA-Bicillin for treatment of children with RHD was made by Pfizer. ACB is supported by an National Health and Medical Research Council (NHMRC) of Australia Early Career Fellowship (1088735)

Is Streptococcus pyogenes resistant or susceptible to Trimethoprim-Sulfamethoxazole?

Streptococcus pyogenes is commonly believed to be resistant to trimethoprim-sulfamethoxazole (SXT), resulting in reservations about using SXT for skin and soft tissue infections (SSTI) where S. pyogenes is involved. S. pyogenes\u27 in vitro susceptibility to SXT depends on the medium\u27s thymidine content. Thymidine allows S. pyogenes to bypass the sulfur-mediated inhibition of folate metabolism and, historically, has resulted in apparently reduced susceptibility of S. pyogenes to sulfur antibacterials. The low thymidine concentration in Mueller-Hinton agar (MHA) is now regulated. We explored S. pyogenes susceptibility to SXT on various media. Using two sets of 100 clinical S. pyogenes isolates, we tested for susceptibility using SXT Etests on MHA containing defibrinated horse blood and 20 mg/liter &beta;-NAD (MHF), MHA with sheep blood (MHS), MHA alone, MHA with horse blood (MHBA), and MHA with lysed horse blood (MHLHBA). European Committee on Antibacterial Susceptibility Testing (EUCAST) breakpoints defined susceptibility (MIC, &le;1 mg/liter) and resistance (MIC, &gt;2 mg/liter). In study 1, 99% of S. pyogenes isolates were susceptible to SXT on MHA, MHBA, and MHLHBA, with geometric mean MICs of 0.04, 0.04, and 0.05 mg/liter, respectively. In study 2, all 100 S. pyogenes isolates were susceptible to SXT on MHF, MHS, MHA, and MHLHBA with geometric mean MICs of 0.07, 0.16, 0.07, and 0.09 mg/liter, respectively. This study confirms the in vitro susceptibility of S. pyogenes to SXT, providing support for the use of SXT for SSTIs. A clinical trial using SXT for impetigo is ongoing

Keeping it real: Virtual connection with SToP trial community navigators

Building trust and forging relationships with remote Aboriginal communities is an essential element of culturally informed, reciprocal research. Historically these relationships have been formed over-time where community members and researchers come together face to face to share their knowledge and yarn in both an informal and formal manner. Researchers from Telethon Kids Institute are partnering with local stakeholders and remote Aboriginal communities in the Kimberley, Western Australia (WA) to support healthy skin through the SToP (See, Treat, Prevent skin sores and scabies) Trial. The SToP trial, a collaboration between Telethon Kids Institute, Kimberley Aboriginal Medical Services (KAMS), Nirrumbuk Environmental Health Services and Western Australia Country Health Services (WACHS) – Kimberley is a clustered randomised trial with a stepped-wedge design. SToP trial consultation with stakeholders and communities commenced in 2016 to proceed consenting in 2018 and trial commencement in 2019. Since that time, the SToP trial team have been conducting intermittent fieldwork in nine remote Aboriginal communities in the Kimberley. However, due to the COVID-19 pandemic when Aboriginal health leaders recommended a cessation to research related travel in northern WA from March 11, 2020 to prevent the incursion of COVID-19 into Aboriginal communities with health vulnerabilities, crucial face-to-face yarning was no longer possible. At the time it appeared the existing relationships with communities involved in our research (the SToP trial) would be challenging to maintain without this ability to visit the communities. Fortunately, when tested, this assumption was erroneous. Here we report the successful use of technology to bridge the inability to visit communities in 2020 due to COVID-19. The Telethon Kulunga Aboriginal Unit (Kulunga) and SToP trial team members were able to connect virtually with Community Navigators from the Dampier Peninsula communities. The initial virtual meeting using Microsoft Teams technology involved four Community Navigators and their mentor, three Telethon Kids Institute and five Kulunga staff members. Community Navigators joined Microsoft Teams from their respective communities and Kulunga and Telethon Kids Institute staff joined from their homes. Not only was this an exciting new way of communicating, it enabled existing relationships to continue to be strengthened. Since the initial meeting, the teams have continued to meet virtually, and plan SToP trial health promotion activities including a community-driven, collaborative music video. While the significance of face-to-face yarning can never be overstated, having to adjust to a new way of yarning has reiterated the importance of connection, albeit virtually. Unfortunately, due to technical limitations, intermittent internet connectivity and various other challenges, there has been no opportunity to engage virtually with SToP trial communities in the East Kimberley. However, we continue to seek ways where virtual communication in these communities is possible

Standardization of Epidemiological Surveillance of Group A Streptococcal Impetigo

Impetigo is a highly contagious bacterial infection of the superficial layer of skin. Impetigo is caused by group A Streptococcus (Strep A) and Staphylococcus aureus, alone or in combination, with the former predominating in many tropical climates. Strep A impetigo occurs mainly in early childhood, and the burden varies worldwide. It is an acute, self-limited disease, but many children experience frequent recurrences that make it a chronic illness in some endemic settings. We present a standardized surveillance protocol including case definitions for impetigo including both active (purulent, crusted) and resolving (flat, dry) phases and discuss the current tests used to detect Strep A among persons with impetigo. Case classifications that can be applied are detailed, including differentiating between incident (new) and prevalent (existing) cases of Strep A impetigo. The type of surveillance methodology depends on the burden of impetigo in the community. Active surveillance and laboratory confirmation is the preferred method for case detection, particularly in endemic settings. Participant eligibility, surveillance population and additional considerations for surveillance of impetigo, including examination of lesions, use of photographs to document lesions, and staff training requirements (including cultural awareness), are addressed. Finally, the core elements of case report forms for impetigo are presented and guidance for recording the course and severity of impetigo provided

Molecular diagnosis of scabies using a novel probe-based polymerase chain reaction assay targeting high-copy number repetitive sequences in the Sarcoptes scabiei genome

Background The suboptimal sensitivity and specificity of available diagnostic methods for scabies hampers clinical management, trials of new therapies and epidemiologic studies. Additionally, parasitologic diagnosis by microscopic examination of skin scrapings requires sample collection with a sharp scalpel blade, causing discomfort to patients and difficulty in children. Polymerase chain reaction (PCR)-based diagnostic assays, combined with non-invasive sampling methods, represent an attractive approach. In this study, we aimed to develop a real-time probe-based PCR test for scabies, test a non-invasive sampling method and evaluate its diagnostic performance in two clinical settings. Methodology/Principal findings High copy-number repetitive DNA elements were identified in draft Sarcoptes scabiei genome sequences and used as assay targets for diagnostic PCR. Two suitable repetitive DNA sequences, a 375 base pair microsatellite (SSR5) and a 606 base pair long tandem repeat (SSR6), were identified. Diagnostic sensitivity and specificity were tested using relevant positive and negative control materials and compared to a published assay targeting the mitochondrial cox1 gene. Both assays were positive at a 1:100 dilution of DNA from a single mite; no amplification was observed in DNA from samples from 19 patients with other skin conditions nor from house dust, sheep or dog mites, head and body lice or from six common skin bacterial and fungal species. Moderate sensitivity of the assays was achieved in a pilot study, detecting 5/7 (71.4% [95% CI: 29.0% - 96.3%]) of clinically diagnosed untreated scabies patients). Greater sensitivity was observed in samples collected by FLOQ swabs compared to skin scrapings. Conclusions/Significance This newly developed qPCR assay, combined with the use of an alternative non-invasive swab sampling technique offers the possibility of enhanced diagnosis of scabies. Further studies will be required to better define the diagnostic performance of these tests

Modes of transmission and attack rates of group A Streptococcal infection: a protocol for a systematic review and meta-analysis

Background Group A Streptococcus (Strep A) is an important cause of mortality and morbidity globally. This bacterium is responsible for a range of different infections and post-infectious sequelae. Summarising the current knowledge of Strep A transmission to humans will address gaps in the evidence and inform prevention and control strategies. The objective of this study is to evaluate the modes of transmission and attack rates of group A streptococcal infection in human populations. Methods This systematic review protocol was prepared according to the Preferred Reporting Items for Systematic reviews and Meta-analysis Protocols (PRISMA-P) 2015 Statement. Using a comprehensive search strategy to identify any transmission studies that have been published in English since 1980, full-text articles will be identified and considered for inclusion against predefined criteria. We will include all studies reporting on Strep A transmission, who have identified a mode of transmission, and who reported attack rates. Risk of bias will be appraised using an appropriate tool. Our results will be described narratively and where feasible and appropriate, a meta-analysis utilizing the random-effects model will be used to aggregate the incidence proportions (attack rates) for each mode of transmission. In addition, we will also evaluate the emm genotype variants of the M protein causing Strep A infection and the association with transmission routes and attack rates, if any, by setting, socioeconomic background and geographical regions. Discussion We anticipate that this review will contribute to elucidating Strep A modes of transmission which in turn, will serve to inform evidence-based strategies including environmental health activities to reduce the transmission of Strep A in populations at risk of severe disease. Trial registration Systematic review registration: PROSPERO ( CRD42019138472 )