Topological mechanics of gyroscopic metamaterials

Topological mechanical metamaterials are artificial structures whose unusual properties are protected very much like their electronic and optical counterparts. Here, we present an experimental and theoretical study of an active metamaterial -- comprised of coupled gyroscopes on a lattice -- that breaks time-reversal symmetry. The vibrational spectrum of these novel structures displays a sonic gap populated by topologically protected edge modes which propagate in only one direction and are unaffected by disorder. We present a mathematical model that explains how the edge mode chirality can be switched via controlled distortions of the underlying lattice. This effect allows the direction of the edge current to be determined on demand. We envision applications of these edges modes to the design of loss-free, one-way, acoustic waveguides and demonstrate this functionality in experiment

Modelling water diffusion in plasticizers: development and optimization of a force field for 2,4-dinitroethylbenzene and 2,4,6-trinitroethylbenzene

A classical all-atom force field has been developed for 2,4,6-trinitroethylbenzene and 2,4-dinitroethylbenzene and applied in molecular dynamics simulations of the two pure and two mixed plasticizer systems. Bonding parameters and partial charges were derived through electronic and geometry optimization of the single molecules. The other required parameters were derived from values already available in the literature for generic nitro aromatic compounds, which were adjusted to reproduce to a high level of accuracy the densities of 2,4-dinitroethylbenzene, 2,4,6-trinitroethylbenzene and the energetic plasticizers K10 and R8002. This force field has been applied to both K10 and R8002, which when used as plasticizers form an energetic binder with nitrocellulose. Nitrocellulose decomposes in storage, under varying conditions, but in particular where it may become increasingly dry. Following the derivation of the force field, we have therefore applied it to calculate water diffusion coefficients for each of the different materials at 298 K and 338 K, thereby providing a starting point for understanding water behaviour in a nitrocellulose binder

Chief medical officers\u27 perceptions of disease management programs

The purpose of this article is to examine chief medical officers\u27 (CMOs) perception of disease management programs. Five open-ended questions, each addressing a major issue in the development of disease management programs, were given to 31 CMOs who attended a series of invitation-only conferences on disease management in the fall of 1999. Qualitative data analysis was conducted using the transcripts on each of the issues. Overall, the CMOs viewed the emergence of capitated disease management programs positively. They considered the population of a program to be the contractual patients and/or those at risk for the target disease. On the issue of quality and cost, they preferred an optimal balance between the two. They saw the Internet as an opportunity for the education of patients as well as providers. However, they were concerned about patient confidentiality and further widening of the gap between those who have the financial means to access healthcare and those who do not. In spite of concerns expressed about the current generation of disease management programs, the CMOs held an optimistic view of the future of these programs. To become better accepted, disease management programs must address the issues of confidentiality and quality of care

Employee benefit plan audits: knowledge spillover for improving quality

This study provides a unique glimpse into the work of non-BigN accounting firms offering Employee Benefit Plan (EBP) audit services for single employer defined contribution plans. The study examines knowledge spillover from joint services and EBP auditor specialization to improve EBP audit quality. EBPs often incur low-quality audits, resulting in penalties assessed by the Department of Labor (DOL) for deficiencies. Companies may feel a sense of comfort hiring the same auditor they used for their company financial statements, but the EBP audits require the auditor to possess specialized knowledge beyond the requirements for the financial statements to confirm compliance with the Employee Retirement Income Security Act (ERISA) and DOL regulations. In line with the knowledge spillover theory, the study finds weak support that joint services contribute to EBP audit quality in the form of DOL communications received on Form 5500 filings. Additionally, when auditors perform more EBP audits, they are less likely to receive DOL communication, and the quality of the audit improves. The number of audits performed becomes more significant in the absence of knowledge spillover from joint services. The research responds to calls by regulators and professional bodies to identify key determinants of EBP audit quality. The results are relevant for plan sponsors in selecting audit firms and for auditors determining services to offer to clients. Additionally, the study extends prior audit quality literature by examining a niche market within auditing services and contributes to the ongoing debate over providing expanded services to audit clients. The paper includes a discussion of future research opportunities for EBP audit quality. JEL Classifications: J3, K2, L2, M1, M4, M4

Seasonal Dynamics of Atlantic Herring (Clupea harengus L.) Populations Spawning in the Vicinity of Marginal Habitats

Gillnet sampling and analyses of otolith shape, vertebral count and growth indicated the presence of three putative Atlantic herring (Clupea harengus L.) populations mixing together over the spawning season February–June inside and outside an inland brackish water lake (Landvikvannet) in southern Norway. Peak spawning of oceanic Norwegian spring spawners and coastal Skagerrak spring spawners occurred in March–April with small proportions of spawners entering the lake. In comparison, spawning of Landvik herring peaked in May–June with high proportions found inside the lake, which could be explained by local adaptations to the environmental conditions and seasonal changes of this marginal habitat. The 1.85 km2 lake was characterized by oxygen depletion occurring between 2.5 and 5 m depth between March and June. This was followed by changes in salinity from 1–7‰ in the 0–1 m surface layer to levels of 20–25‰ deeper than 10 m. In comparison, outside the 3 km long narrow channel connecting the lake with the neighboring fjord, no anoxic conditions were found. Here salinity in the surface layer increased over the season from 10 to 25‰, whereas deeper than 5 m it was stable at around 35‰. Temperature at 0–5 m depth increased significantly over the season in both habitats, from 7 to 14°C outside and 5 to 17°C inside the lake. Despite differences in peak spawning and utilization of the lake habitat between the three putative populations, there was an apparent temporal and spatial overlap in spawning stages suggesting potential interbreeding in accordance with the metapopulation concept

High background rates of positive tuberculosis-specific interferon-? release assays in a low prevalence region of UK: a surveillance study

Background: Background rates of latent tuberculosis infection in low prevalence regions of Britain are unknown. These would be valuable data for interpreting positive IGRA results, and guiding cost-benefit analyses. The management of a large outbreak of tuberculosis occurring in a rural district hospital provided an opportunity to determine the background rates and epidemiology of IGRA-positivity amongst unselected hospital patients in a low-prevalence region of U.K.Methods: As part of a public health surveillance project we identified 445 individuals exposed to the index cases for clinical assessment and testing by a TB-specific interferon-? release assay (IGRA): T-Spot.TB. Uniquely, an additional comparator group of 191 age-matched individuals without specific recent exposure, but with a similar age distribution and demographic, were recruited from the same wards where exposure had previously occurred, to undergo assessment by questionnaire and IGRA. Results: Rates of IGRA positivity were 8.7% (95%CI, 4.2-13, n=149) amongst unexposed patients, 9.5%(3.0-22, n=21) amongst unexposed staff, 22%(14–29, n=130) amongst exposed patients, 11%(6.1-16, n=142) amongst exposed staff. Amongst the individuals without history of recent exposure to the outbreak, IGRA-positivity was associated with prior TB treatment (OR11, P.04) and corticosteroid use (OR5.9, P.02). Background age-specific prevalences of IGRA-positivity amongst unexposed individuals were: age <40 0%(N/A), age 40–59 15%(12–29), age 60–79 7.0%(1.1-13), age?80 10%(5.9-19).Conclusions: Background rates of IGRA-positivity remain high amongst unselected white-Caucasian hospital inpatients in U.K. These data will aid interpretation of future outbreak studies. As rates peak in the 5th and 6th decade, given an ageing population and increasing iatrogenic immunosuppression, reactivation of LTBI may be a persistent hazard in this population for several decades to come

Treating the symptoms or the disease? Analysing the UK Online Safety Act's approach to digital regulation

In recent years, the pace of Internet regulation around the world has quickened, with states increasingly confident that they can and should hold major platform companies to account. New laws have been developed to address the risks of digital technologies and law‐makers have drawn on familiar regulatory principles and legacy frameworks in addressing them. But the nature of the technologies and the business models supporting them bring new challenges which make it less clear that old approaches will work. To succeed, legislative frameworks must evolve and adapt. Against this backdrop we assess the UK's Online Safety Act 2023 (OSA), which was expected to provide an innovative and broad‐reaching ‘systems‐based’ approach to reducing user risks and harms, particularly in relation to child safety. We argue that although the Act does incorporate measures to regulate platform design, it fails to fully embrace this and faces some challenges in ensuring proportionality and accountability. We conclude that the development of the OSA is hampered by a legacy focus on content controls which may limit its ability to effectively improve online safety, particularly as services evolve