Practicing care-full scholarship: Exploring the use of ‘visual informed consent’ in a study of motherhood, health and agroecology in Coventry, UK

The demand for alternative methods of providing informed consent is increasing, especially in research with marginalised (or illiterate) research participants. This article discusses the co-creation of a visual informed consent (VIC), in collaboration with an artist. The VIC was inspired by the experience of obtaining informed consent from a group of migrant women with limited English proficiency, in empirical research undertaken on agroecology and health in Coventry, UK. Reflecting further on its creation and wider utility, this article explores the inner values that might guide researchers and lead to the co-creation of care-full tools that meet the needs of research participants. Specifically, this includes, reflecting on the iterative process of developing a VIC and using an ethics of care as a primary conceptual framework. Findings reveal that participants’ understanding of ethical issues is facilitated using visual illustrations. It is argued that the creation of a VIC requires the researcher to be attentive to the embodied nature of research practice and guided by an ethics of care. A conceptual framework that integrates care and embodiment is presented, with the intention that it may further support the development of care-full research by others

Design strategy of a 2.8–3.6 GHz 20W GaN Doherty power amplifier

This paper presents the design of a 20W GaN Doherty Power Amplifier working in the range 2.8 GHz–3.6 GHz. The design strategy adopted for the design of the Doherty output combiner is discussed, which consists in embedding the device parasitics into the latter, implemented as a multi-stage quarter-wavelength transformer, in order to achieve wideband behaviour. The saturated output power ranges from 42dBm to 44 dBm, with a corresponding drain efficiency in excess of 47%. The efficiency at 6 dB of output back-off is higher than 42% over the whole frequency band, and the small-signal gain is higher than 10 dB. Due to the discrepancies of the measured scattering parameters compared to the simulated ones, which could not be corrected with post-tuning, a redesign of the prototype is ongoing

3.1-3.6 GHz 22 W GaN Doherty Power Amplifier

This paper presents a Doherty power amplifier working from 3.1 GHz to 3.6 GHz. It adopts 10 W packaged GaN HEMTs from Cree/Wolfspeed and achieves a saturated output power in excess of 43.4 dBm. Saturated efficiency ranges from 57.7 % to 75.2 %, while efficiency at 6 dB back-off is between 44.2 % and 59.8 %. System-level simulations at 3.5 GHz adopting a 16QAM signal with 5 MHz bandwidth and 4 dB peak to average power ratio showed an adjacent channel power ratio of -28 dBc/Hz without pre-distortion, at an average output power of 43 dBm and with an average efficiency of 71 %

A 3-3.8 GHz Class-J GaN HEMT Power Amplifier

This paper presents a wideband class J power amplifier (PA) based on a packaged 10 W GaN HEMT device covering the 3 GHz to 3.8 GHz frequency range. A good trade-off between efficiency and gain has been pursued in synthesizing the second harmonic output termination. The achieved output power is in excess of 41 dBm with drain efficiency ranging from 59 % to 65.5 % and a small signal gain above 14 dB. Preliminary large signal measurements at 3.3 GHz confirm the proper behavior of the PA

Broadband Class-J GaN Doherty Power Amplifier

This paper presents a broadband 3 GHz–3.7GHz class-J Doherty power amplifier exploiting second harmonic tuning in the output network. Furthermore, the output impedance inverter is eliminated and its effect is embedded in the main device’s output matching network, thus trading off among bandwidth, efficiency, and gain. The proposed amplifier adopts two 10W packaged GaN transistors, and it achieves in measurement 60–74%, and 46–50% drain efficiency at saturation and 6 dB output back-off, respectively, with a saturated output power of 43 dBm–44.2dBm and a small-signal gain of 10 dB–13 dB. The proposed DPA exhibits a simulated adjacent channel power ratio less than 30 dBc at 36dBm average output power when a 16-QAM modulation with 5 MHz bandwidth is applied to the 3.5 GHz carrier

Ultralow-Power Digital Control and Signal Conditioning in GaAs MMIC Core Chip for X-Band AESA Systems

This work presents the design and characterization of an ultralow-power core chip for electronically scanned arrays at X-band, implemented in 0.25-/0.5-μm E-/D-mode gallium arsenide (GaAs) pHEMT technology. In particular, design details are given about the two core functional blocks embedded in the microwave monolithic integrated circuit (MMIC): a 12-bit phase and amplitude control circuit and an 18-bit serial-to-parallel (S2P) interface. The S2P interface was designed resorting to a custom symmetric device model, expressly conceived for the time-domain simulations required for digital circuits. Due to the adoption of a differential structure with resistive pull-ups, it achieves a state-of-the-art power consumption of 2.2 mW/bit and nearly 87% yield. The analog circuit includes a 6-bit phase shifter (PS) and a 6-bit attenuator. To mitigate risks, two different PS architectures have been developed and are compared in this work, discussing advantages and drawbacks of the different solutions. Since the two designs share the same target specifications, a truly fair comparison can be made not only in terms of performance but also concerning robustness and repeatability, thus providing useful guidelines for the selection of the most appropriate strategy. In particular, it is shown that one architecture outperforms the other by about 2 dB and 1.5° in terms of insertion loss and rms phase error, respectively

Association Between Posttraumatic Stress Disorder Following Myocardial Infarction and Liver Enzyme Levels: A Prospective Study

Background: Research in rodents demonstrated that psychological stress increases circulating levels of alanine transaminase, aspartate transaminase, and alkaline phosphatase reflecting liver injury. Moreover, chronic posttraumatic stress disorder and transaminases predicted coronary heart disease. Aims: To investigate the hypothesis that severity of posttraumatic stress disorder following myocardial infarction would prospectively relate to liver enzymes. Methods: Study participants were 24 patients (mean 59±7years, 79% men) with an interviewer-rated diagnosis of posttraumatic stress disorder caused by an index myocardial infarction 3±3months before. After a mean follow-up of 26±6months, patients had a clinical interview to reassess posttraumatic stress disorder severity, a medical history, and blood collected to determine liver enzymes. Results: Total posttraumatic stress disorder symptoms assessed at study entry prospectively predicted plasma levels of alanine transaminase (r=.47, p=.031) and alkaline phosphatase (r=.57, p=.004), but not of aspartate transaminase (p=.15), controlling for follow-up duration and antidepressant use. Total posttraumatic stress disorder symptoms assessed at follow-up were associated with alanine transaminase (r=.72, p=.004), aspartate transaminase (r=.60, p=.018), and alkaline phosphatase (r=.64, p=.001) in the 16 patients who had maintained diagnostic posttraumatic stress disorder, but not in all 24 patients. Conclusions: The severity of posttraumatic stress disorder following myocardial infarction was associated with mild increase in liver enzyme levels, suggesting that chronic psychological stress relates to hepatic damage in humans. This might help to explain the previously observed increased cardiovascular risk in chronically traumatized individual

Use of a biochar-based formulation for coating corn seeds

The series of experiments summarized here were conducted with the objective to evaluate the benefits of using biochar for coating corn seeds. Seeds coated with a slurry containing bio-based ingredients and biochar were tested for germination and vigor, and for their potential to being infected by the fungus Aspergillus flavus, using a novel single seed incubator specifically designed for these purposes. Biochar-treated seeds were also planted for two years in experimental fields in the Mississippi Delta to evaluate their effect on corn yield and aflatoxin contamination of kernels. Experiments were conducted with two types of commercial biochar; one was obtained from hardwood residues and the other from coconut shells. Application of both types of biochar for coating the seeds did not affect seed germination and vigor. However, treated seeds showed increased wettability and a more rapid water uptake. This resulted in a 8.5% shortening of germination time. Microbiological analysis using plate culturing and qPCR methods showed that biochar was not conducive to the growth of A. flavus. This was also confirmed by analyzing soil samples that were collected from experimental fields located in the Mississippi Delta. Most importantly, although aflatoxin contamination was different in the two experimental years, aflatoxin contamination of corn kernels was not affected by biochar-based formulations

Association Between Posttraumatic Stress Disorder Following Myocardial Infarction and Liver Enzyme Levels: A Prospective Study

Research in rodents demonstrated that psychological stress increases circulating levels of alanine transaminase, aspartate transaminase, and alkaline phosphatase reflecting liver injury. Moreover, chronic posttraumatic stress disorder and transaminases predicted coronary heart disease

The effects of benzofury (5-APB) on the dopamine transporter and 5-HT2-dependent vasoconstriction in the rat

5-APB, commonly marketed as ‘benzofury’ is a new psychoactive substance and erstwhile ‘legal high’ which has been implicated in 10 recent drug-related deaths in the UK. This drug was available on the internet and in ‘head shops’ and was one of the most commonly sold legal highs up until its recent UK temporary ban (UK Home Office). Despite its prominence, very little is known about its pharmacology. This study was undertaken to examine the pharmacology of 5-APB in vitro. We hypothesized that 5-APB would activate the dopamine and 5-HT systems which may underlie its putative stimulant and hallucinogenic effects. Autoradiographic studies showed that 5-APB displaced both [125I]RTI-121 and [3H]ketanserin from rat brain tissue suggesting affinity at the dopamine transporter and 5-HT2 receptor sites respectively. Voltammetric studies in rat accumbens brain slices revealed that 5-APB slowed dopamine reuptake, and at high concentrations caused reverse transport of dopamine. 5-APB also caused vasoconstriction of rat aorta, an effect antagonized by the 5-HT2A receptor antagonist ketanserin, and caused contraction of rat stomach fundus, which was reversed by the 5-HT2B receptor antagonist RS-127445. These data show that 5-APB interacts with the dopamine transporter and is an agonist at the 5-HT2A and 5-HT2B receptors in the rat. Thus 5-APB’s pharmacology is consistent with it having both stimulant and hallucinogenic properties. In addition, 5-APB’s activity at the 5-HT2B receptor may cause cardiotoxicity