Focussed microwave heating using degenerate and non-degenerate cavity modes

Microwave ovens have long been recognised as a means of reducing heating times versus conventional convection ovens. The principle design feature is based on the procurement of uniform heating within any material placed in the interior of the microwave cavity oven. Materials within the oven are subjected to a degree of heating dependent on their electromagnetic properties. For many applications, it is desirable to maintain control over the distribution of heat deposition. This can be achieved through focussing of the electromagnetic field within the cavity. Two new mechanisms are identified where an increased level of control over the heating pattern and its location could be advantageous. The research described within this thesis aims to improve heating selectivity in microwave cavity ovens by the identification and enhanced control of modal patterns in degenerate and non-degenerate resonators. This is achieved through the analysis of two novel oven arrangements. The first of these addresses the requirement for highly selective heating in hyperthermia treatment. It is demonstrated that proper selection of a forced degenerate mode set can lead to an enhancement in field focussing within the centre of the cavity through constructive and destructive interference of the fields in each mode pattern. It is found that a highly selective peak of field can be produced within the centre of a large cylindrical waveguide cavity for the purpose of hyperthermia treatment. The peak is produced using a quasi degenerate mode set excited at approximately 1:3GHz. The second example presents an open oven design for the curing of epoxy and encapsulant materials within the micro-electronics packaging industry. It is intended that the oven be placed on the arm of a precision alignment machine such that the curing and placement stages of production be combined, suggesting an increase in production efficiency. Two excitation schemes are presented based on the coupling of quasi degenerate mode sets through a wide frequency range and the excitation of a single high order mode enabling uniform field distribution for heating of encapsulant material and increased selective heating through spatial alignment of modal field peaks, respectively. Experimental results demonstrate the viability of the open-ended microwave oven for curing. Both proposed excitation methods within the open oven design are investigated with results presented. Optimisation of the heating fields is achieved through inclusion of lowloss materials within the oven. Curing of an encapsulant material covering a commercial chip package is achieved and the overall design validated

High resolution synchrotron imaging of wheat root hairs growing in soil and image based modelling of phosphate uptake

Root hairs are known to be highly important for uptake of sparingly soluble nutrients, particularly in nutrient deficient soils. Development of increasingly sophisticated mathematical models has allowed uptake characteristics to be quantified. However, modelling has been constrained by a lack of methods for imaging live root hairs growing in real soils.We developed a plant growth protocol and used Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM) to uncover the 3D interactions of root hairs in real soil. We developed a model of phosphate uptake by root hairs based directly on the geometry of hairs and associated soil pores as revealed by imaging.Previous modelling studies found that root hairs dominate phosphate uptake. By contrast, our study suggests that hairs and roots contribute equally. We show that uptake by hairs is more localised than by roots and strongly dependent on root hair and aggregate orientation.The ability to image hair-soil interactions enables a step change in modelling approaches, allowing a more realistic treatment of processes at the scale of individual root hairs in soil pores

High-resolution synchrotron imaging shows that root hairs influence rhizosphere soil structure formation

In this paper, we provide direct evidence of the importance of root hairs on pore structure development at the root-soil interface during the early stage of crop establishment. This was achieved by use of high resolution (~5 μm) synchrotron radiation computed tomography (SRCT) to visualise both the structure of root hairs and the soil pore structure in plant-soil microcosms. Two contrasting genotypes of barley (Hordeum vulgare L.), with and without root hairs, were grown for 8 days in microcosms packed with sandy loam soil at 1.2 g cm-3 36 dry bulk density. Root hairs were visualised within air filled pore spaces, but not in the fine-textured soil regions. - We found that the genotype with root hairs significantly altered the porosity and connectivity of the detectable pore space (> 5 μm) in the rhizosphere, as compared with the no-hair mutants. Both genotypes showed decreasing pore-space between 0.8 mm and 0.1 mm from the root surface. Interestingly the root-hair-bearing genotype had a significantly greater soil pore volume-fraction at the root-soil interface. - Effects of pore structure on diffusion and permeability were estimated to be functionally insignificant under saturated conditions when simulated using image based modelling

Phylogenetic ctDNA analysis depicts early-stage lung cancer evolution.

The early detection of relapse following primary surgery for non-small-cell lung cancer and the characterization of emerging subclones, which seed metastatic sites, might offer new therapeutic approaches for limiting tumour recurrence. The ability to track the evolutionary dynamics of early-stage lung cancer non-invasively in circulating tumour DNA (ctDNA) has not yet been demonstrated. Here we use a tumour-specific phylogenetic approach to profile the ctDNA of the first 100 TRACERx (Tracking Non-Small-Cell Lung Cancer Evolution Through Therapy (Rx)) study participants, including one patient who was also recruited to the PEACE (Posthumous Evaluation of Advanced Cancer Environment) post-mortem study. We identify independent predictors of ctDNA release and analyse the tumour-volume detection limit. Through blinded profiling of postoperative plasma, we observe evidence of adjuvant chemotherapy resistance and identify patients who are very likely to experience recurrence of their lung cancer. Finally, we show that phylogenetic ctDNA profiling tracks the subclonal nature of lung cancer relapse and metastasis, providing a new approach for ctDNA-driven therapeutic studies

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same regio

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Building Economically, Socially and Ecologically Resilient Fisheries and Coastal Communities: A Policy Paper

Building resilient fisheries and coastal communities for Newfoundland and Labrador’s future is one of the most important opportunities and challenges of our time. In many of our coastal communities, fisheries continue to be the major source of employment and wealth generation, a crucial part of rural economies, of our identity and our cultural heritage. The owner-operator small and medium-scale enterprises and fish plants generate most of this wealth and employment. In recent decades our fisheries and coastal communities have weathered some severe storms, including the 1990s collapse of our groundfish stocks. Their capacity to respond to such challenges without fundamental cultural, social and ecological change is evidence of their resilience, which is now in serious jeopardy. It is threatened by unfounded claims that our fisheries are broken and the best way to fix them is by turning fisheries quotas and licenses into commodities that can be bought and then sold to the highest bidder. It is also suggested that we get rid of policies that limit vertical integration, although such policies have kept access to many (not all) of our fish resources widely dispersed around our coasts. As a result they have both enhanced the employment and wealth they produce for the province, and anchored much of that wealth in the households of people who work in the industry and in the communities where they live. This is not the time to jettison them