Blackbox macro-modeling of the nonlinearity based on Volterra series representation of X-parameters

Volterra series representation is a powerful mathematical model for nonlinear devices. However, the difficulties in determining higher-order Volterra kernels limited its broader applications. This paper proposed a systematic approach that enables a convenient extraction of Volterra kernels from X-parameters for the first time. Then the Vandermonde method is employed to separate different orders of Volterra kernels at the same frequency, which leads to a highly efficient extraction process. The proposed Volterra series representation based on X-parameters is further benchmarked for verification. The proposed new algorithm is very useful for the blackbox macro-modeling of nonlinear devices and systems. © 2014 IEEE.postprin

Volterra Series-Based Time-Domain Macromodeling of Nonlinear Circuits

Volterra series (VS) representation is a powerful mathematical model for nonlinear circuits. However, the difficulties in determining higher order Volterra kernels limited its broader applications. In this paper, a systematic approach that enables a convenient extraction of Volterra kernels from X-parameters is presented. A concise and general representation of the output response due to arbitrary number of input tones is given. The relationship between Volterra kernels and X-parameters is explicitly formulated. An efficient frequency sweep scheme and an output frequency indexing scheme are provided. The least square linear regression method is employed to separate different orders of Volterra kernels at the same frequency, which leads to the obtained Volterra kernels complete. The proposed VS representation based on X-parameters is further validated for time-domain verification. The proposed method is systematic and general-purpose. It paves the way for time-domain simulation with X-parameters and constitutes a powerful supplement to the existing blackbox macromodeling methods for nonlinear circuits.postprin

Perceptions of health risk among parents of overweight children: a cross-sectional study within a cohort.

OBJECTIVE: To identify the socio-demographic and behavioural characteristics associated with perceptions of weight-related health risk among the parents of overweight children. METHODS: Baseline data from a cohort of parents of children aged 4-11 years in five areas in England in 2010-2011 were analysed; the sample was restricted to parents of overweight children (body mass index ≥ 91(st) centile of UK 1990 reference; n=579). Associations between respondent characteristics and parental perception of health risk associated with their child's weight were examined using logistic regression analyses. RESULTS: Most parents (79%) did not perceive their child's weight to be a health risk. Perception of a health risk was associated with recognition of the child's overweight status (OR 10.59, 95% CI 5.51 to 20.34), having an obese child (OR 4.21, 95% CI 2.28 to 7.77), and having an older child (OR 2.67, 95% CI 1.32 to 5.41). However, 41% of parents who considered their child to be overweight did not perceive a health risk. CONCLUSIONS: Parents that recognise their child's overweight status, and the parents of obese and older children, are more likely to perceive a risk. However, many parents that acknowledge their child is overweight do not perceive a related health risk

Activation of the damage-associated molecular pattern receptor P2X7 induces interleukin-1B release from canine monocytes

P2X7, a damage-associated molecular pattern receptor and adenosine 5\u27-triphosphate (ATP)-gated cation channel, plays an important role in the activation of the NALP3 inflammasome and subsequent release of interleukin (IL)-1β from human monocytes; however its role in monocytes from other species including the dog remains poorly defined. This study investigated the role of P2X7 in canine monocytes, including its role in IL-1β release. A fixed-time flow cytometric assay demonstrated that activation of P2X7 by extracellular ATP induces the uptake of the organic cation, YO-PRO-12+, into peripheral blood monocytes from various dog breeds, a process impaired by the specific P2X7 antagonist, A438079. Moreover, in five different breeds, relative P2X7 function in monocytes was about half that of peripheral blood T cells but similar to that of peripheral blood B cells. Reverse transcription-PCR demonstrated the presence of P2X7, NALP3, caspase-1 and IL-1β in LPSprimed canine monocytes. Immunoblotting confirmed the presence of P2X7 in LPS-primed canine monocytes. Finally, extracellular ATP induced YO-PRO-12+ uptake into and IL-1β release from these cells, with both processes impaired by A438079. These results demonstrate that P2X7 activation induces the uptake of organic cations into and the release of IL-1β from canine monocytes. These findings indicate that P2X7 may play an important role in IL-1β-dependent processes in dogs

Quality of life among caregivers of people with end-stage kidney disease managed with dialysis or comprehensive conservative care

BACKGROUND: To measure health-related and care-related quality of life among informal caregivers of older people with end-stage kidney disease (ESKD), and to determine the association between caregiver quality of life and care recipient's treatment type. METHODS: A prospective cross-sectional study was conducted. Three renal units in the UK and Australia were included. Informal caregivers of people aged ≥75 years with ESKD managed with dialysis or comprehensive conservative non-dialytic care (estimated glomerular filtration (eGFR) ≤10 mL/min/1.73m2) participated. Health-related quality of life (HRQoL) was assessed using Short-Form six dimensions (SF-6D, 0-1 scale) and care-related quality of life was assessed using the Carer Experience Scale (CES, 0-100 scale). Linear regression assessed associations between care-recipient treatment type, caregiver characteristics and the SF-6D utility index and CES scores. RESULTS: Of 63 caregivers, 49 (78%) were from Australia, 26 (41%) cared for an older person managed with dialysis, and 37 (59%) cared for an older person managed with comprehensive conservative care. Overall, 73% were females, and the median age of the entire cohort was 76 years [IQR 68-81]. When adjusted for caregiver sociodemographic characteristics, caregivers reported significantly worse carer experience (CES score 15.73, 95% CI 5.78 to 25.68) for those managing an older person on dialysis compared with conservative care. However, no significant difference observed for carer HRQoL (SF-6D utility index - 0.08, 95% CI - 0.18 to 0.01) for those managing an older person on dialysis compared with conservative care. CONCLUSIONS: Our data suggest informal caregivers of older people on dialysis have significantly worse care-related quality of life (and therefore greater need for support) than those managed with comprehensive conservative care. It is important to consider the impact on caregivers' quality of life when considering treatment choices for their care recipients

Health-related quality of life and well-being in people over 75 years of age with end-stage kidney disease managed with dialysis or comprehensive conservative care: A cross-sectional study in the UK and Australia

© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. Objective To measure health-related quality of life (HRQoL) and well-being in older people with end-stage kidney disease (ESKD) and to determine the association between treatment type and sociodemographic characteristics on these outcome measures. In addition, to assess the convergent validity between the HRQoL and well-being measure and their feasibility and acceptability in this population. Design Prospective cross-sectional study. Setting Three renal units in the UK and Australia. Participants 129 patients with ESKD managed with dialysis or with an estimated glomerular filtration ≤10 mL/min/1.73 m 2 and managed with comprehensive conservative, non-dialytic care. Outcome measures HRQoL and well-being were assessed using Short-Form six dimensions (SF-6D, 0-1 scale); Kidney Disease Quality of Life (KDQOL-36) (0-100 scale) and Investigating Choice Experiments Capability Measure-Older people (ICECAP-O, 0-1 scale). Linear regression assessed associations between treatment, HRQoL and well-being. Pearson's correlation coefficient assessed convergent validity between instruments. Results Median age of 81 years (IQR 78-85), 65% males; 83 (64%) were managed with dialysis and 46 (36%) with conservative care. When adjusted for treatment type and sociodemographic variables, those managed on dialysis reported lower mean SF-6D utility (-0.05, 95% CI-0.12 to 0.01); lower KDQOL Physical Component Summary score (-3.17, 95% CI-7.61 to 1.27); lower Mental Component Summary score (-2.41, 95% CI-7.66 to 2.84); lower quality of life due to burden (-28.59, 95% CI-41.77 to-15.42); symptoms (-5.93, 95% CI-14.61 to 2.73) and effects of kidney disease (-16.49, 95% CI-25.98 to-6.99) and lower overall ICECAP-O well-being (-0.07, 95% CI-0.16 to 0.02) than those managed conservatively. Correlation between ICECAP-O well-being and SF-6D utility scores was strong overall, 0.65 (

A randomised trial of an internet weight control resource: The UK Weight Control Trial [ISRCTN58621669]

BACKGROUND: Obesity treatment is notoriously unsuccessful and one of the barriers to successful weight loss reported by patients is a lack of social support. The Internet offers a novel and fast approach to the delivery of health information, enabling 24-hour access to help and advice. However, much of the health information available on the Internet is unregulated or not written by qualified health professionals to provide unbiased information. The proposed study aims to compare a web-based weight loss package with traditional dietary treatment of obesity in participants. The project aims to deliver high quality information to the patient and to evaluate the effectiveness of this information, both in terms of weight loss outcomes and cost-effectiveness. METHODS: This study is a randomised controlled trial of a weight loss package against usual care provided within General Practice (GP) surgeries in Leeds, UK. Participants will be recruited via posters placed in participating practices. A target recruitment figure of 220 will enable 180 people to be recruited (allowing for 22% dropout). Participants agreeing to take part in the study will be randomly allocated using minimisation to either the intervention group, receiving access to the Internet site, or the usual care group. The primary outcome of the study will be the ability of the package to promote change in BMI over 6 and 12 months compared with traditional treatment. Secondary outcomes will be the ability of the Internet package to promote change in reported lifestyle behaviours. Data will be collected on participant preferences, adherence to treatment, health care use and time off work. Difference in cost between groups in provision of the intervention and the cost of the primary outcome will also be estimated. CONCLUSION: A positive result from this study would enhance the repertoire of treatment approaches available for the management of obesity. A negative result would be used to inform the research agenda and contribute to redefining future strategies for tackling obesity