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Construction of a destabilizing nonlinearity for discrete-time uncertain Lurye systems
No full textThis paper considers the instability of a Lurye system consisting of an uncertain, discrete-time, linear time-invariant plant in feedback with a slope-restricted nonlinearity. There is a large literature on analyzing the stability of such systems. This includes various conditions for proving stability of the Lurye system, including the Circle criterion and the use of O’Shea-Zames-Falb multipliers. In many cases, these conditions are sufficient but not necessary to prove stability. In contrast, there is also some work to construct specific nonlinearities that demonstrate the instability of the Lurye system (with the nominal plant dynamics). This paper considers a more general case where the plant has dynamic uncertainty. The goal is to construct both an instance of the uncertain model and a corresponding nonlinearity that combined make the Lurye system unstable. A limit cycle oscillation is also computed to verify the instability. A simple example is provided to demonstrate the results
Physical activity, sedentary time and breast cancer risk: A Mendelian randomization study
No full textObjectives: Physical inactivity and sedentary behaviour are associated with higher breast cancer risk in observational studies, but ascribing causality is difficult. Mendelian randomization (MR) assesses causality by simulating randomized trial groups using genotype. We assessed whether lifelong physical activity or sedentary time, assessed using genotype, may be causally associated with breast cancer risk overall, pre/post-menopause, and by case-groups defined by tumour characteristics.Methods: We performed two-sample inverse-variance-weighted MR using individual-level Breast Cancer Association Consortium case-control data from 130,957 European-ancestry women (69,838 invasive cases), and published UK Biobank data (n=91,105-377,234). Genetic instruments were single nucleotide polymorphisms (SNPs) associated in UK Biobank with wrist-worn accelerometer-measured overall physical activity (nsnps=5) or sedentary time (nsnps=6), or accelerometer-measured (nsnps=1) or self-reported (nsnps=5) vigorous physical activity.Results: Greater genetically-predicted overall activity was associated with lower breast cancer risk, overall (OR=0.59; 95%CI 0.42-0.83 per-standard deviation [SD; ~8 milligravities acceleration]) and for most case-groups. Genetically-predicted vigorous activity was associated with lower risk of pre/perimenopausal breast cancer (OR=0.62; 95%CI 0.45-0.87, ≥3 vs. 0 self-reported days/week), with consistent estimates for most case-groups. Greater genetically-predicted sedentary time was associated with higher hormone-receptor-negative tumour risk (OR=1.77; 95%CI 1.07-2.92 per-SD [~7% time spent sedentary]), with elevated estimates for most case-groups. Results were robust to sensitivity analyses examining pleiotropy (including weighted-median-MR, MR-Egger). Conclusion: Our study provides strong evidence that greater overall physical activity, greater vigorous activity, and lower sedentary time are likely to reduce breast cancer risk. More widespread adoption of active lifestyles may reduce the burden from the most common cancer in women.<br/
Introduction for the 5th International Meeting on Internet and Audiology: Special Issue of the American Journal of Audiology
No full textEffect of aging treatment on phase evolution and mechanical properties of selective laser melted Al-Mg-Er-Zr alloy
No full textEr and Zr modified Al-Mg alloy was manufactured by selective laser melting. The effect of aging treatment on phase evolution and mechanical properties of alloy has been studied. The results show that bimodal grain structures (2.8±1.1 μm) could be obtained, thanks to the Al3Zr primary phases promoting the formation of equiaxed grains (0.8±0.3 μm) at the boundary of molten pool. During the aging of 375 ℃, Al3(Er,Zr) particles with the size of 2-5 nm were produced via synergistic precipitation of Er and Zr, which would greatly improve the strength and reach 510±9 MPa. At the same time, the Mg-rich phase was dissolved, the Mn-rich phase was precipitated, and dislocations could accelerate the diffusion of solute atoms during the evolution of the phases
Looking into the IL-1 of the storm: Are inflammasomes the link between immunothrombosis and hyperinflammation in cytokine storm syndromes?
No full textInflammasomes and the interleukin (IL)-1 family of cytokines are key mediators of both inflammation and immunothrombosis. Inflammasomes are responsible for the release of the pro-inflammatory cytokines IL-1β and IL-18, as well as releasing tissue factor (TF), a pivotal initiator of the extrinsic coagulation cascade. Uncontrolled production of inflammatory cytokines results in what is known as a “cytokine storm” leading to hyperinflammatory disease. Cytokine storms can complicate a variety of diseases and results in hypercytokinemia, coagulopathies, tissue damage, multi-organ failure and death. Patients presenting with cytokine storm syndromes have a high mortality rate, driven in part by disseminated intravascular coagulation (DIC). Whilst our knowledge on the factors propagating cytokine storms is increasing, how cytokine storm influences DIC remains unknown, and therefore treatments for diseases, where these aspects are a key feature are limited, with most targeting specific cytokines. Currently, no therapies target the immunothrombosis aspect of hyperinflammatory syndromes. Here we discuss how targeting the inflammasome and pyroptosis may be a novel therapeutic strategy for the treatment of hyperinflammation and its associated pathologies
Valorization of Lignocellulose by Producing Polyhydroxyalkanoates Under Circular Bioeconomy Premises: Facts and Challenges
No full textIn light of the current concerns about environmental issues caused by the excessive use of fossil resources, more emphasis has been paid to the transition to a sustainable and circular economy. Bioplastics as eco-friendly products originating from biomass wastes have gained much attention to solve the problem of plastic pollution. Among them, polyhydroxyalkanoates (PHAs) are microbial polyesters produced using various feedstocks—renewable or recycled waste materials—contributing to a more sustainable commercial plastic life cycle by being a part of a circular bioeconomy. However, the scale-up of the PHAs process cost-effectively and sustainably remains challenging for large-scale industrial applications. This perspective article provides a comprehensive overview of the current insights into lignocellulosic biomass's role in achieving a circular bioeconomy. Emerging greener biomass conversion technologies are discussed to characterize energy demand, cost, and sustainability within biorefineries PHAs production. In addition, recent advances in synthetic biology and fermentation processes for PHAs production are discussed. Technological challenges, i.e., bioreactor set-up, downstream operation, and inconsistent properties to improve the sustainable production of PHAs and to help transfer this technology to real-world application, are also addressed
Social support resilience as a protective mental health factor in postgraduate researchers’ experiences: a longitudinal analysis.
No full textPurpose: The aims of this research were to examine across a six-month period in post-graduate research (PGR) students i. mental health and well-being, ii. the effect of academic pressures on depression, anxiety and well-being, and iii. the extent to which psychological resilience buffered against academic pressures.Design/methodology/approach: This was a longitudinal questionnaire study with predictor variables of six types of academic pressure, outcome variables of depression, anxiety and well-being, and a moderator of resilience.Findings: Well-being significantly worsened across the six month timeframe, but levels of depression and anxiety remained relatively stable. Negative perceptions of academic challenges at baseline significantly predicted anxiety, but not depression or well-being, six months later. Negative appraisals of relationships with supervisors, other university staff, and work peers were not predictors of anxiety. Social support resilience which was present at baseline buffered the relationship between perceived academic challenges and anxiety.Originality: This is the first study to examine the effects of negative perceptions of multiple facets of academic life on depression, anxiety and well-being longitudinally. Additionally, it is the first study to investigate, and demonstrate, the extent to which psychological resilience can lessen the relationship between academic challenges and anxiety over time.Implications: Higher Education Institutions have a duty of care towards PGR students many of whom struggle with escalating interactions between mental health problems and academic pressures. Actively nurturing psychological resilience related to social support is key at the level of the individual students and the PGR community but more broadly at an institutional level. KEYWORDS: post-graduate; doctoral; longitudinal; academic pressures; mental health; depression; anxiety; well-being; psychological resilience; social support<br/
A review of the DTaP-IPV-HB-PRP-T Hexavalent vaccine in pediatric patients
No full textIntroduction: Hexaxim is a hexavalent vaccine approved in 2013 for use the EU as primary and booster vaccination in infants 6 weeks and older, protecting against diphtheria, tetanus, pertussis, poliomyelitis, hepatitis B and Haemophilus influenzae type b.Areas Covered: To evaluate the immunogenicity and reactogenicity (safety) of Hexaxim (Hexyon, Hexacima) in primary and booster vaccine schedules; long-term antibody persistence; concomitant use with other childhood vaccines and use in immunocompromised infants. Hexaxim was found to be noninferior to other hexavalent vaccines on the market, being highly immunogenic for all toxoids/antigens and with an acceptable safety profile. It can be administered concomitantly with other childhood vaccines and provides long lasting immune protection against all diseases, including hepatitis B. Hexaxim can be given as a booster for infants primed with Infanrix Hexa and can be given in a pentavalent-hexavalent-pentavalent series. Hexaxim elicits a similar immune response and safety profile in Human immunodeficiency virus (HIV) positive infants. It has the benefit of being a ready to use liquid formulation, minimising dosage errors and preparation time.Expert Opinion: Hexaxim has an acceptable safety profile and provides immunity against all six targeted diseases, including long lasting hepatitis B antibody persistence. It is an acceptable alternative to other hexavalent vaccines on the market. Further studies are required on the use in immunocompromised patients as well as the antibody persistence of each of the vaccine components
Emotionally Based School Non-Attendance: Two Successful Returns to School Following Lockdown
No full textEmotionally based school non-attendance (EBSNA) needs are complex, with a distinctive combination of risk factors affecting each individual. This study presents an exploration of the perceived facilitators to successful returns to school for two primary-aged children who had previously experienced anxiety around school attendance. The perspectives of parents, school staff, and educational psychologists were gathered using semi-structured interviews to identify effective support. A reflexive thematic analysis was conducted to generate themes. Findings demonstrate that the support in each case was highly individualised. Key facilitators considered to achieve this included: effective home-school communication; taking a functional approach; engaging other professional support; cultivating positive relationships; and practitioners regularly reflecting on their practice. The significant overlap between themes supports an interactionist, ecological model of early identification and intervention for EBSNA difficulties. Implications for practitioners include the need to ensure a reflective, individualised approach, and the importance of facilitating the home-school relationship.Keywords: emotionally based school non-attendance; anxiety; school absenteeism; educational psychology; intervention<br/
A Novel Borinate Ester Copolymer for Poly(Frustrated Lewis Pair) Gels
No full textThe versatile chemistry of boronic acid and boronate ester containing polymers has led to key applications in drug delivery, chemical sensing, and dynamic materials. However, their use in polymeric Frustrated Lewis pair (FLP) remains unreported. In this paper we report the synthesis of a novel fluorinated borinate ester copolymer which, when combined with a suitable Lewis basic copolymer, generates polymeric FLP network capable of responsive gelation. The borinate ester moiety, bis(pentafluorophenyl)borinic acid tetrafluorophenyl ester, was affixed to a polystyrene copolymer by a two-step post-polymerisation modification, which can be easily upscaled and purified. The Gutmann-Beckett method suggests these fluorinated borinate ester moieties are amongst the most Lewis acidic boron-containing polymers reported to date. Upon mixing with a Lewis basic copolymer poly(styrene-co-p-diphenylphosphino styrene), gelation cannot be achieved due to steric hindrance around the Lewis centres. However, network formation can be triggered by addition of small molecules such as diethylazodicarboxylate (DEAD) and cyclic ethers. The physical parameters and nature of the crosslinks of the gels prepared from different crosslinkers were probed by rheology. All networks demonstrated strong elastic behaviour, corresponding to covalently crosslinked materials. DEAD crosslinked gels displayed different behaviour to those triggered by cyclic ethers, indicating that mechanism of small molecule activation also plays an important role in the mechanical properties of poly(FLP) gels