Passive Components Technology for THz-Monolithic Integrated Circuits (THz-MIC)

In this work, a viable passive components and transmission media technology is presented for THz-Monolithic Integrated Circuits (THz-MIC). The developed technology is based on shielded microstrip (S-MS) employing a standard monolithic microwave integrated circuit compatible process. The S-MS transmission media uses a 5-μm layer of benzocyclobutene (BCB) on shielded metalized ground plates avoiding any substrate coupling effects. An insertion loss of less than 3 dB/mm was achieved for frequencies up to 750 GHz. To prove the effectiveness of the technology, a variety of test structures, passive components and antennas have been design, fabricated and characterized. High Q performance was demonstrated making such technology a strong candidate for future THz-MIC technology for many applications such as radar, communications, imaging and sensing

Terahertz Monolithic Integrated Circuits (TMICs) Array Antenna Technology On GaN-on-Low Resistivity Silicon Substrates

In this paper, we have demonstrated a viable microstrip array patch antenna technology for the first time on GaN-on-low resistivity silicon (LR-Si) substrates (ρ <; 40 Ω.cm) at H-band frequencies (220-325 GHz). The developed technology is compatible with standard MMIC technology with no requirement for high temperature processes. To mitigate the losses presented by the substrate and to enhance the performance of the integrated array antenna at THz frequencies, the driven patch is shielded by silicon nitride and gold layer in addition to a layer of benzocyclobutene (BCB). The demonstrated 4×1 array integrated antenna showed a measured resonance frequency in agreement with our simulation at 0.27 THz; a measured S11 as low as -41 dB was obtained. A directivity, gain and radiation efficiency of 11.2 dB, 5.2 dB, and 20% respectively was observed from the 3D EM model for a 5 μm BCB inset. To the authors' knowledge, this is the first demonstration of a THz integrated microstrip array antenna for TMIC technology; this developed technology is promising for high performance III-V electronic material on low resistivity/high dielectric substrates

Genetic disorders on the island of Mauritius

Inherited disorders are an important cause of physical handicap, deafness, mental retardation and blindness. There is considerable variation in the geographic and ethnic distribution of genetic disease due to biological pressures and historical accidents. In this context the relative prevalence of common inherited disorders and the recognition of rare conditions in isolated communities is of great academic importance. Oceanic islands are of special significance in the study of inherited disease. Virtually nothing has been documented concerning genetic disorders on the Island of Mauritius with a population of one million people. This study was undertaken to document the impact of inherited disorders on handicapping conditions in this community. As genetic disease concentrates in institutions, formal screening of all the schools for the deaf and blind, and the associations for the physically and mentally handicapped on Mauritius was undertaken. This involved a careful history, clinical examination and genealogical study, with radiographic, biochemical and ancillary testing performed where appropriate. Referral clinics were also established for the assessment of individuals and families known, or thought to be afflicted with abnormalities or handicap of a genetic origin. To ensure completeness, a similar survey was performed on Rodrigues, a neighbouring island, as this community is included under the responsibilities of the Mauritian Ministry of Health. Accumulated data concerning 681 patients were analysed. Genetic disorders accounted for disability in 265 individuals representing 38,6% of the causes of handicap. Of these persons 54 were deaf, 30 were blind, 99 were mentally retarded and 80 were physically handicapped. Several new entities, considered unique to the area and a consequence of either consanguinity or the founder effect, were documented. Karyotyping on selected individuals was undertaken in the laboratories of the Department of Human Genetics, University of Cape Town. A molecular genetic study of a large family with X-linked deafness of Nance, conducted by the same laboratory, revealed tight linkage with the probe pDP34; linkage analysis was performed on patients with Duchenne muscular dystrophy. The collation of these original data, the delineation of the new genetic conditions and an analysis of the results form the subject of this thesis and provide a basis for the future development of genetic services on Mauritius

Dual barrier InAlN/AlGaN/GaN-on-silicon high-electron-mobility transistors with Pt and Ni based gate stacks

In this work, we report the performance of 3 μm gate length "dual barrier„ InAlN/AlGaN/GaN HEMTs on Si substrates with gate-drain contact separations in the range 4-26 μm. Devices with Pt and Ni based gates were studied and their leakage characteristics are compared. Maximum drain current IDS of 1 A/mm, maximum extrinsic transconductance gm ~203 mS/mm and on-resistance Ron 4.07 Ω mm for gate to drain distance LGD = 4 μm were achieved. Nearly ideal sub-threshold swing of 65.6 mV/dec was obtained for LGD = 14 μm. The use of Pt based gate metal stacks led to a two to three orders of magnitude gate leakage current decrease compared to Ni based gates. The influence of InAlN layer thickness on the transistor transfer characteristics is also discussed

No. 6 - 30th Anniversary Issue

With this issue of the Occasional Papers, we celebrate the 30th anniversary of the founding of the Dean Rusk Center, which bears the name of the late School of Law faculty member who served as secretary of state under Presidents John F. Kennedy and Lyndon B. Johnson from 1961 until 1969. Our purpose in hosting the conference and lectures published in this volume was to provide a forum for developing the comprehensive new focus necessary to met the American foreign policy demands of the 21st century. In so doing, it is our intent that the advice and counsel of the former secretaries of state and speakers in this volume—each of whom has been, directly or indirectly, impacted by the life of Dean Rusk—will bring us closer to being “present at the creation” of a post-modern American foreign policy equipped to deal with the challenges ahead. We hope that this publication, under the auspices of the Center that bears his name, will have an impact that is worthy of the legacy of Dean Rusk

Tackling dementia together via the Australian dementia network (ADNeT): A summary of initiatives, progress and plans

In 2018, the Australian Dementia Network (ADNeT) was established to bring together Australia\u27s leading dementia researchers, people with living experience and clinicians to transform research and clinical care in the field. To address dementia diagnosis, treatment, and care, ADNeT has established three core initiatives: the Clinical Quality Registry (CQR), Memory Clinics, and Screening for Trials. Collectively, the initiatives have developed an integrated clinical and research community, driving practice excellence in this field, leading to novel innovations in diagnostics, clinical care, professional development, quality and harmonization of healthcare, clinical trials, and translation of research into practice. Australia now has a national Registry for Mild Cognitive Impairment and dementia with 55 participating clinical sites, an extensive map of memory clinic services, national Memory and Cognition Clinic Guidelines and specialized screening for trials sites in five states. This paper provides an overview of ADNeT\u27s achievements to date and future directions. With the increase in dementia cases expected over coming decades, and with recent advances in plasma biomarkers and amyloid lowering therapies, the nationally coordinated initiatives and partnerships ADNeT has established are critical for increased national prevention efforts, co-ordinated implementation of emerging treatments for Alzheimer\u27s disease, innovation of early and accurate diagnosis, driving continuous improvements in clinical care and patient outcome and access to post-diagnostic support and clinical trials. For a heterogenous disorder such as dementia, which is now the second leading cause of death in Australia following cardiovascular disease, the case for adequate investment into research and development has grown even more compelling

Pulmonary function deficits in newborn screened infants with cystic fibrosis managed with standard UK care are mild and transient

With the advent of novel designer molecules for cystic fibrosis (CF) treatment, there is huge need for early-life clinical trial outcomes, such as infant lung function (ILF). We investigated the degree and tracking of ILF abnormality during the first 2 years of life in CF newborn screened infants. Forced expiratory volume in 0.5 s (FEV₀.₅), lung clearance index (LCI) and plethysmographic functional residual capacity were measured at ∼3 months, 1 year and 2 years in 62 infants with CF and 34 controls. By 2 years there was no significant difference in FEV₀.₅ z-score between CF and controls, whereas mean LCI z-score was 0.81 (95% CI 0.45–1.17) higher in CF. However, there was no significant association between LCI z-score at 2 years with either 3-month or 1-year results. Despite minimal average group changes in any ILF outcome during the second year of life, marked within-subject changes occurred. No child had abnormal LCI or FEV₀.₅ on all test occasions, precluding the ability to identify “high-risk” infants in early life. In conclusion, changes in lung function are mild and transient during the first 2 years of life in newborn screened infants with CF when managed according to a standardised UK treatment protocol. Their potential role in tracking disease to later childhood will be ascertained by ongoing follow-up

Nanoscale structural and chemical analysis of F-implanted enhancement-mode InAlN/GaN heterostructure field effect transistors

We investigate the impact of a fluorine plasma treatment used to obtain enhancement-mode operation on the structure and chemistry at the nanometer and atomic scales of an InAlN/GaN field effect transistor. The fluorine plasma treatment is successful in that enhancement mode operation is achieved with a +2.8 V threshold voltage. However, the InAlN barrier layers are observed to have been damaged by the fluorine treatment with their thickness being reduced by up to 50%. The treatment also led to oxygen incorporation within the InAlN barrier layers. Furthermore, even in the as-grown structure, Ga was unintentionally incorporated during the growth of the InAlN barrier. The impact of both the reduced barrier thickness and the incorporated Ga within the barrier on the transistor properties has been evaluated theoretically and compared to the experimentally determined two-dimensional electron gas density and threshold voltage of the transistor. For devices without fluorine treatment, the two-dimensional electron gas density is better predicted if the quaternary nature of the barrier is taken into account. For the fluorine treated device, not only the changes to the barrier layer thickness and composition, but also the fluorine doping needs to be considered to predict device performance. These studies reveal the factors influencing the performance of these specific transistor structures and highlight the strengths of the applied nanoscale characterisation techniques in revealing information relevant to device performance.</jats:p