Evaluating the Effect of Using Precision Alignment Dowels on Connection Repeatability of Waveguide Devices at Frequencies from 750 GHz to 1.1 THz

This paper describes an investigation into the effects of using additional precision alignment dowel pins on the connection repeatability performance of waveguide interfaces at submillimeter-wave frequencies. The waveguide interface type that was used for this investigation is an adapted version of the `precision' UG-387 (i.e. based on the MIL-DTL-3922/67 design), manufactured by Virginia Diodes, Inc. The investigation was undertaken in the WM-250 waveguide band (i.e. at frequencies ranging from 750 GHz to 1.1 THz). Connection performance is compared with and without the use of added precision dowel pins in the inner dowel holes of this flange type. The repeatability of the measurements is assessed using statistical techniques, in terms of the experimental standard deviation in both the real and imaginary components of the complex-valued linear reflection coefficient

An intra-laboratory investigation of on-wafer measurement reproducibility at millimeter-wave frequencies

Understanding the relative contribution of contact repeatability and overall reproducibility for on-wafer measurements provides useful insight into the significance of measurement comparisons. We report on an intra-laboratory investigation into contact repeatability and the variation that may be anticipated when measurements are reproduced in different laboratories using different equipment. We pay particular attention to the dispersion in measurement results arising from the use of on-wafer and off-wafer calibration. Experimental results are reported for measurements in the frequency range 140 GHz to 220 GHz, together with preliminary estimates of the repeatability limits for this type of measurement

‘Mind the Gap’ . . . Establishing Measurement Capability in the Terahertz Gap Region – from 0.1 THz to 1.1 THz

This paper reviews the current state-of-the-art of measurements made using vector network analysers operating in the 0.1 THz to 1.1 THz frequency range. The paper concentrates on the development of three types of measurement capability: (i) in rectangular metallic waveguides; (ii) on-wafer planar circuits; (iii) bulk material characterisations. The paper describes progress to date with establishing this measurement capability and reviews the remaining challenges facing this measurement community

Metrology State-of-the-Art and Challenges in Broadband Phase-Sensitive Terahertz Measurements

The two main modalities for making broadband phase-sensitive measurements at terahertz (THz) frequencies are vector network analyzers (VNA) and time-domain spectrometers (TDS). These measuring instruments have separate and fundamentally different operating principles and methodologies, and they serve very different application spaces. The different architectures give rise to different measurement challenges and metrological solutions. This article reviews these two measurement techniques and discusses the different issues involved in making measurements using these systems. Calibration, verification, and measurement traceability issues are reviewed, along with other major challenges facing these instrument architectures in the years to come. The differences in, and similarities between, the two measurement methods are discussed and analyzed. Finally, the operating principles of electro-optic sampling (EOS) are briefly discussed. This technique has some similarities to TDS and shares application space with the VNA

An interlaboratory study of the reproducibility of on-wafer S-parameter measurements from 140 GHz to 220 GHz

The development, modelling and characterization of millimeter-wave semiconductor devices calls for accurate and reproducible on-wafer measurements. We report on an interlaboratory study involving on-wafer S-parameter measurements in the 140 GHz to 220 GHz band, conducted by three well-established measurement laboratories. The measurements can be used to form typical reproducibility limits for these measurements when conducted in different laboratories using different equipment and calibration methods

Strategies for Traceable Submillimeter-Wave Vector Network Analyzer

This paper presents a strategy for achieving metrological traceability using vector network analyzers (VNAs) at submillimeter-wave frequencies (300-3000 GHz). The strategy includes the use of traceable calibration techniques designed for operation at these frequencies. Slight, but significant, physical differences between the waveguide line standards, used during calibration, are accommodated by applying a weighting technique to combine results using different calibration lines. Measurement uncertainty is assessed by analyzing replicate measurement data, to take account of the different waveguide interface interactions that occur when the line standards are connected to the VNA. The strategy is illustrated using measurements made in the WM-250 (750-1100 GHz) waveguide band

The impact of contact tracing in clustered populations

The tracing of potentially infectious contacts has become an important part of the control strategy for many infectious diseases, from early cases of novel infections to endemic sexually transmitted infections. Here, we make use of mathematical models to consider the case of partner notification for sexually transmitted infection, however these models are sufficiently simple to allow more general conclusions to be drawn. We show that, when contact network structure is considered in addition to contact tracing, standard “mass action” models are generally inadequate. To consider the impact of mutual contacts (specifically clustering) we develop an improvement to existing pairwise network models, which we use to demonstrate that ceteris paribus, clustering improves the efficacy of contact tracing for a large region of parameter space. This result is sometimes reversed, however, for the case of highly effective contact tracing. We also develop stochastic simulations for comparison, using simple re-wiring methods that allow the generation of appropriate comparator networks. In this way we contribute to the general theory of network-based interventions against infectious disease

Astrocytes display cell autonomous and diverse early reactive states in familial amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis is a rapidly progressive and fatal disease. Although astrocytes are increasingly recognized contributors to the underlying pathogenesis, the cellular autonomy and uniformity of astrocyte reactive transformation in different genetic forms of amyotrophic lateral sclerosis remain unresolved. Here we systematically examine these issues by using highly enriched and human induced pluripotent stem cell-derived astrocytes from patients with VCP and SOD1 mutations. We show that VCP mutant astrocytes undergo cell-autonomous reactive transformation characterized by increased expression of complement component 3 (C3) in addition to several characteristic gene expression changes. We then demonstrate that isochronic SOD1 mutant astrocytes also undergo a cell-autonomous reactive transformation, but that this is molecularly distinct from VCP mutant astrocytes. This is shown through transcriptome-wide analyses, identifying divergent gene expression profiles and activation of different key transcription factors in SOD1 and VCP mutant human induced pluripotent stem cell-derived astrocytes. Finally, we show functional differences in the basal cytokine secretome between VCP and SOD1 mutant human induced pluripotent stem cell-derived astrocytes. Our data therefore reveal that reactive transformation can occur cell autonomously in human amyotrophic lateral sclerosis astrocytes and with a striking degree of early molecular and functional heterogeneity when comparing different disease-causing mutations. These insights may be important when considering astrocyte reactivity as a putative therapeutic target in familial amyotrophic lateral sclerosis

SISTAQUIT: training health care providers to help pregnant Aboriginal and Torres Strait Islander women quit smoking. A cluster randomised controlled trial

Background: About 44% of Indigenous Australian women smoke during pregnancy, compared with 12% of pregnant non-Indigenous women. Health care providers can assist smoking cessation, but they are not typically trained in culturally appropriate methods. Objectives: To determine whether a health care worker training intervention increases smoking cessation rates among Indigenous pregnant smokers compared with usual care. Methods and analysis: Supporting Indigenous Smokers to Assist Quitting (SISTAQUIT) study is a multicentre, hybrid type 1, pragmatic, cluster randomised controlled trial that compares the effects of an intervention for improving smoking cessation by pregnant Indigenous women (16 years or older, 32 weeks’ gestation or less) with usual care. Twenty-one health services caring for Indigenous people in five Australian jurisdictions were randomised to the intervention (ten sites) or control groups (eleven sites). Health care providers at intervention sites received smoking cessation care training based on the ABCD (ask/assess; brief advice; cessation; discuss psychosocial context) approach to smoking cessation for Indigenous women, an educational resource package, free oral nicotine replacement therapy for participating women, implementation support, and trial implementation training. Health care providers in control group services provided usual care. Primary outcome: abstinence from smoking (self-reported abstinence via survey, validated by carbon monoxide breath testing when possible) four weeks after enrolment in the study. Secondary outcomes: health service process evaluations; knowledge, attitudes, and practices of health care providers; and longer term abstinence, perinatal outcomes, and respiratory outcomes for babies (to six months). Ethics approval: The human research ethics committees of the University of Newcastle (H-2015-0438) and the Aboriginal Health and Medical Research Council of NSW (1140/15) provided the primary ethics approval. Dissemination of results: Findings will be disseminated in peer-reviewed publications, at local and overseas conferences, and via public and social media, and to participating health services in art-based formats and reports. Policy briefs will be communicated to relevant government organisations. Trial registration: Australia New Zealand Clinical Trials Registry, ACTRN12618000972224 (prospective)