Computational electromagnetic (CEM) model validation against measured and calculated results

The paper presents examples of the validation of numerical models using measured and calculated results from a range of research projects undertaken at York. These aim to show that both the measurement and computational model are approximate representations of the real-world, and that significant effort must be made to ensure that they are sufficiently similar if useful results and validation are to be obtained. We shall also discuss how the choice of metrics for the comparison of numerical, analytical and measured data is influenced by the nature of the EM problem being investigate

Field statistics in an enclosure with an aperture: Effect of Q-factor and Number of Modes

The statistics of the fields within an enclosure illuminated by an external field via an aperture have been investigated using Monte-Carlo methods. The field statistics in the volume of the enclosure are shown to correspond to the Rayleigh statistics found in properly functioning reverberation chambers when a sufficiently large number of modes is excited. The variation of field behaviour near the conducting walls is investigated. The deviation of the field statistics from the Rayleigh distribution as the number of excited modes falls is also investigated

The use of reverberation chambers in the quantitative assessment of the risk associated with the installation of electronic systems on vehicles.

The EU SAFETEL Project was concerned with the safety implications of installing electronic equipment on vehicles. Part of the project concerned the development of a risk assessment model suitable for predicting an upper bound on the probability of failure of an electronic system installed inside a vehicle that is irradiated externally or internally. Only limited information on the immunity of the device and associated cabling is required. As an example, the model is used to demonstrate the probability of failure of a system due to irradiation from Digital Audio Broadcast (DAB) transmitters in the United Kingdom (UK). The failure probability is found to be highly sensitive to the clearance above the vehicle chassis of wire looms attached to the system, and to the accuracy with which the electric field is measured during an immunity test for the system/cable combination. The failure probability predicted by the risk assessment model is consistent with common observations of a log-normal distribution in the terminating power of receiving cables inside an irradiated vehicle confirmed by measurements in a reverberation chamber. In this paper we describe the experiments undertaken in the reverberation chamber and present the results of the experiments which illustrate their correspondence with the theoretical and observed statistics of the power received by cable terminations in a lossy enclosed space such as a vehicle. The rotational positions of the stirrer substitute for the statistical nature of the excitation fields in the vehicle and the variations of positioning of the cables within the vehicle. An example system comprising a multisensor ultrasonic parking warning system was used in the experiments and good agreement was achieved between the predictions and the observed failures of the system when under test. This paper is illustrates the potential for the use of reverberation chambers for testing systems that may be installed on vehicles and integrating the test results with a quantitative risk assessment of the vehicle operated in a real environment

Efficient simulations for automotive design

Some preliminary results are presented for the statistical coupling of EM radiation to a transmission line inside a lossy chamber with an aperture. The rapid Intermediate Level Circuit Modelling (ILCM) technique has been used to obtain the results, which have relevance to the calculation of the probability of failure of a vehicle subsystem in situ

A cross-sectional assessment of metabolic syndrome in HIV-infected people of low socioeconomic status receiving antiretroviral therapy

BACKGROUND: Metabolic syndrome (MetS) is a constellation of symptoms used as a measure to identify patients at increased risk for cardiovascular disease, type 2 diabetes, and all-cause mortality. The results of prolonged life expectancy and cumulative toxic effects of antiretroviral therapy increase the chance that HIV can cause clinical abnormalities, including MetS. METHODS: We evaluated 89 people living with HIV (PLWH; mean age 48 ± 7 years; mean duration of HIV infection 17 ± 12 years; 47% men; 66% African-American, 22% Hispanic, and 10% non-Hispanic white; and 84% unemployed) enrolled in a community-based exercise training and nutrition education program targeting individuals of low socio-economic status (SES). The prevalence of MetS characteristics and the factors associated with the presence of MetS were analyzed. RESULTS: One in three (33%; 12 men and 17 women) PLWH met ATPIII criteria for MetS. In our cohort, MetS was driven by high waist circumference and elevated blood pressure. In addition, higher use of protease inhibitors, elevated hemoglobin A1c (HbA1c), greater self-reported daily caloric intake and consumption of carbohydrates, sugar, added sugar, and higher glycemic load were found among the individuals with MetS, compared to those without it. Elevated HbA1c and high total sugar consumption were the strongest predictors and accounted for 30% of the occurrence of MetS. CONCLUSIONS: The overall prevalence of MetS in our PLWH cohort receiving antiretroviral therapy is higher than previously reported in the general population and in other PLWH cohorts. Additional work is needed to determine whether MetS is a more disease dependent or lifestyle dependent condition in PLWH

Effect of Dupilumab on Sleep Apnea Severity in Patients With Chronic Rhinosinusitis

Patients with chronic rhinosinusitis (CRS) report improved sleep quality after dupilumab, an anti IL4/13 therapy. Concurrent CRS and obstructive sleep apnea (OSA) cases are not rare, and CRS seemingly raises nasal resistance. Thus, we hypothesized that improved sleep quality by dupilumab therapy in CRS patients might be due to lowered nasal resistance and subsequent improvement of unrecognized comorbid OSA. Patients with concurrent CRS and OSA were recruited. Nasal resistance was measured invasively with transnasal pressure and flow data collected during normal respiration in the supine position. Results from the first five participants did not support our hypothesis. Subjective and objective measures for CRS and nasal resistance values were improved with dupilumab therapy in CRS patients with nasal polyps. However, apnea severity and sleep-related subjective parameters did not change. In the patients with CRS without nasal polyps, no significant changes in either CRS or OSA-related measures were observed

A comparison of the radiosensitisation ability of 22 different element metal oxide nanoparticles using clinical megavoltage X-rays

Background: A wide range of nanoparticles (NPs), composed of different elements and their compounds, are being developed by several groups as possible radiosensitisers, with some already in clinical trials. However, no systematic experimental survey of the clinical X-ray radiosensitising potential of different element nanoparticles has been made. Here, we directly compare the irradiation-induced (10 Gy of 6-MV X-ray photon) production of hydroxyl radicals, superoxide anion radicals and singlet oxygen in aqueous solutions of the following metal oxide nanoparticles: Al2O3, SiO2, Sc2O3, TiO2, V2O5, Cr2O3, MnO2, Fe3O4, CoO, NiO, CuO, ZnO, ZrO2, MoO3, Nd2O3, Sm2O3, Eu2O3, Gd2O3, Tb4O7, Dy2O3, Er2O3 and HfO2. We also examine DNA damage due to these NPs in unirradiated and irradiated conditions. Results: Without any X-rays, several NPs produced more radicals than water alone. Thus, V2O5 NPs produced around 5-times more hydroxyl radicals and superoxide radicals. MnO2 NPs produced around 10-times more superoxide anions and Tb4O7 produced around 3-times more singlet oxygen. Lanthanides produce fewer hydroxyl radicals than water. Following irradiation, V2O5 NPs produced nearly 10-times more hydroxyl radicals than water. Changes in radical concentrations were determined by subtracting unirradiated values from irradiated values. These were then compared with irradiation-induced changes in water only. Irradiation-specific increases in hydroxyl radical were seen with most NPs, but these were only significantly above the values of water for V2O5, while the Lanthanides showed irradiation-specific decreases in hydroxyl radical, compared to water. Only TiO2 showed a trend of irradiation-specific increase in superoxides, while V2O5, MnO2, CoO, CuO, MoO3 and Tb4O7 all demonstrated significant irradiation-specific decreases in superoxide, compared to water. No irradiation-specific increases in singlet oxygen were seen, but V2O5, NiO, CuO, MoO3 and the lanthanides demonstrated irradiation-specific decreases in singlet oxygen, compared to water. MoO3 and CuO produced DNA damage in the absence of radiation, while the highest irradiation-specific DNA damage was observed with CuO. In contrast, MnO2, Fe3O4 and CoO were slightly protective against irradiation-induced DNA damage. Conclusions: Beyond identifying promising metal oxide NP radiosensitisers and radioprotectors, our broad comparisons reveal unexpected differences that suggest the surface chemistry of NP radiosensitisers is an important criterion for their success

Critical Dietetics and Sustainable Food Systems

In this chapter, we invite readers to consider a food system that is based on values where individual health, the health of the society (social system) and ecosystem health are of equal importance. With this as a lens, there is a clear need to move beyond the biosciences to consider transdisciplinary approaches as important for nutrition and Dietetic in today and tomorrow’s reality