Theory and practice of deliberative participation in policy analysis

Abstract: The inclusion of a post-positivist thinking to policy making is a response to criticism raised against the limitations positivists impose on the policy making process. Policy-making and analysis are mainly seen as activities driven by empiricist ideals, quantitative facts, technocrats and experts while citizens’ (deliberative) views are excluded or marginalised. Participatory (or deliberative) public policy analysis is a supporting approach presented by post-positivists to embrace democratic ideals through a better informed public policy process that includes normative and valuative knowledge through mainly qualitative processes. This approach supports the notion of multiple methods of inquiry in the contexts of argumentation, judgment and public debate. In defining policy analysis, post-positivists have opened an opportunity for deliberative approaches. This provides an opportunity specifically to further enhance the policy process through participatory evaluation. In this article a logical qualitative inquiry accompanied by a theoretical analysis by way of a literature analysis was employed as the preferred strategy to determine the questions that are most significant to the topic, context and reliability of the research

Feedhorn-integrated THz QCL local oscillators for the LOCUS atmospheric sounder

The LOCUS atmospheric sounder is a satellite-borne THz radiometer concept, for studying molecular species in the mesosphere and lower thermosphere. We report waveguide-integrated THz quantum-cascade lasers for use as 3.5 THz local oscillators. A waveguide-integration scheme, using an integrated diagonal feedhorn significantly improves power outcoupling. 1.3 mW THz emission is demonstrated in a space-qualified Stirling cryocooler at 57 K, with ∼15° beam divergence

Electromagnetic modelling of a terahertz-frequency quantum-cascade laser integrated with dual diagonal feedhorns

We present an electromagnetic model of a THz QCL, integrated with a micro-machined waveguide and dual diagonal feedhorns, enabling simultaneous access to both facets of the QCL. A hybrid finite-element/Fourier transform approach enables analysis of both the near and far-fields in agreement with experimental observations. The far-field pattern shows enhancement of the beam profile when compared with an unmounted QCL, in terms of beam divergence and side-lobe suppression ratio

Electromagnetic-field analysis of diagonal-feedhorn antennas for terahertz-frequency quantum-cascade laser integration

We present an electromagnetic-field analysis of a terahertz-frequency quantum-cascade laser (THz QCL) integrated with a mechanically micro-machined waveguide cavity and diagonal feedhorn. A hybrid finite-element/Fourier transform approach enables analysis of both the near-field and far-field regions and is shown to agree well with experimental observations. The far-field antenna patterns show enhancement of the beam profile when compared with an unmounted QCL, in terms of beam divergence and side-lobe suppression ratio. Furthermore, we demonstrate integration of the QCL with dual diagonal feedhorns, enabling simultaneous access to both facets of the QCL, underpinning future integration with a satellite-based receiver and frequency-stabilization subsystem

Quantum‐Cascade Laser emission at 3.5 THz from dual diagonal feedhorns

The LOCUS satellite (Linking Observations of Climate, the Upper Atmosphere and Space weather) is a proposed mission to explore and observe key gas species within the upper atmosphere using a novel terahertz-frequency (THz) heterodyne spectrometer, in which the emission spectra are simultaneously recorded in four channels in the 0.8–4.7 THz band [1]. THz quantum-cascade lasers (QCLs) will be exploited as local oscillators for the first time in space because they are powerful, yet compact THz sources, providing > 1 mW continuous-wave output at key LOCUS frequencies (3.5 and 4.7 THz). Furthermore, they have been integrated successfully into precision-micro-machined waveguide blocks and operated in space-qualified Stirling-cycle cryo-coolers (~60 K) [2]. A key development challenge will be stabilising the emission frequency of the QCL by locking it to a stable reference oscillator. In this paper, we present a new QCL dual-feedhorn integration technique, which advances this goal by enabling access to radiation emitted from both facets of the QCL simultaneously. In this configuration, the THz emission may be coupled simultaneously to a mixer and to a stabilisation subsystem. Figure 1(a) shows the integration of a 3.5 THz QCL into a precision micro-machined channel in a copper block. A second, symmetrical copper block is placed on top of this to form a rectangular waveguide around the QCL, with a diagonal feedhorn at either end. Figure 1(b) shows the simulated far-field beam pattern for a single feedhorn at 3.5 THz, in which the maximum collected power is represented in the bright central area. Figure 1(c) shows the experimental results for the dual-feedhorn waveguide block, in which the radiation from each horn is reflected onto the same plane, and measured using a raster-scanned Golay-cell detector. Good agreement with the simulated single-feedhorn emission has been observed, with similar beam width and side-lobe content. In conclusion, the integration of a 3.5-THz QCL into a dual-feedhorn waveguide block has been demonstrated. This opens the way towards simultaneous integration of the QCL with a frequency stabilisation system and a supra-THz mixer

Waveguide-integrated THz Quantum-Cascade Lasers for Atmospheric-Research Satellite Payloads

Terahertz-frequency quantum-cascade lasers (THz QCLs) are compact, electrically-driven sources of narrowband radiation in the ~2–5 THz band. Numerous scientifically important gas-phase species within the Earth’s upper atmosphere have distinctive spectral features within this band, making QCLs attractive sources for spectroscopic and radiometric atmospheric studies. In this paper, we demonstrate the integration of a QCL with a satellite-compliant cryocooler, precision-micromachined wave-guide, a pair of diagonal feedhorns and a Cassegrain telescope, as key steps toward a complete 3.5 THz integrated receiver system

An Integrated 3.5-THz QCL Optical Breadboard System for the LOCUS Atmospheric Sounder

An “elegant breadboard” system has been developed, which demonstrates the integration of terahertz-frequency (THz) sources, optics and compact cryocooler technology for the LOCUS satellite (Linking Observations of Climate, the Upper Atmosphere and Space Weather). This proposed satellite instrument has the aim of providing the first global mapping of key molecular species within the mesosphere and lower thermosphere (MLT) from low-earth orbit (LEO), using compact radiometers operating in the 0.8–4.7 THz band and a set of infrared detectors. The LOCUS THz radiometers will incorporate planar-Schottky-diode (SD) mixers, driven using waveguide-integrated local-oscillators (LOs). The LOs will be based on SD multipliers operating at 0.8 and 1.1 THz, and THz quantum-cascade lasers (QCLs) operating at 3.5 and 4.7 THz. A key technological challenge, addressed by the LOCUS elegant breadboard, is the integration of these components into a compact and robust satellite payload, including space-qualified cryocooler technology, and suitable fore-optics. In this paper, we discuss recent progress in QCL integration within the 3.5-THz channel

3.5 THz quantum-cascade laser emission from dual diagonal feedhorns

Antenna-pattern measurements obtained from a double-metal supra-terahertz-frequency (supra-THz) quantum cascade laser (QCL) are presented. The QCL is mounted within a mechanically micro-machined waveguide cavity containing dual diagonal feedhorns. Operating in continuous-wave mode at 3.5 THz, and at an ambient temperature of ∼60 K, QCL emission has been directed via the feedhorns to a supra-THz detector mounted on a multi-axis linear scanner. Comparison of simulated and measured far-field antenna patterns shows an excellent degree of correlation between beamwidth (full-width-half-maximum) and sidelobe content and a very substantial improvement when compared with unmounted devices. Additionally, a single output has been used to successfully illuminate and demonstrate an optical breadboard arrangement associated with a future supra-THz Earth observation space-borne payload. Our novel device has therefore provided a valuable demonstration of the effectiveness of supra-THz diagonal feedhorns and QCL devices for future space-borne ultra-high-frequency Earth-observing heterodyne radiometers

Optical Breadboard Integration of a 3.5-THz Quantum-Cascade Laser Local-Oscillator for the LOCUS Atmospheric Sounder

An “elegant breadboard” system has been developed, which demonstrates the integration of terahertz-frequency (THz) sources, optics and compact cryocooler technology for the LOCUS satellite (Linking Observations of Climate, the Upper Atmosphere and Space Weather). This proposed satellite instrument has the aim of providing the first global mapping of key molecular species within the mesosphere and lower thermosphere (MLT) from low-earth orbit (LEO), using compact radiometers operating in the 0.8–4.7 THz band and a set of infrared detectors. The LOCUS THz radiometers will incorporate planar-Schottky-diode (SD) mixers, driven using waveguide-integrated local-oscillators (LOs). The LOs will be based on SD multipliers operating at 0.8 and 1.1 THz, and THz quantum-cascade lasers (QCLs) operating at 3.5 and 4.7 THz. A key technological challenge, addressed by the LOCUS elegant breadboard, is the integration of these components into a compact and robust satellite payload, including space-qualified cryocooler technology, and suitable fore-optics. In this paper, we discuss recent progress in QCL integration within the 3.5-THz channel

Relations between C9orf72 expansion size in blood, age at onset, age at collection and transmission across generations in patients and presymptomatic carriers

A (GGGGCC) n repeat expansion in C9orf72 gene is the major cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). The relations between the repeats size and the age at disease onset (AO) or the clinical phenotype (FTD vs. ALS) were investigated in 125 FTD, ALS, and presymptomatic carriers. Positive correlations were found between repeats number and the AO (p < 10 e−4 ) but our results suggested that the association was mainly driven by age at collection (p < 10 e−4 ). A weaker association was observed with clinical presentation (p = 0.02), which became nonsignificant after adjustment for the age at collection in each group. Importantly, repeats number variably expanded or contracted over time in carriers with multiple blood samples, as well as through generations in parent-offspring pairs, conversely to what occurs in several expansion diseases with anticipation at the molecular level. Finally, this study establishes that measure of repeats number in lymphocytes is not a reliable biomarker predictive of the AO or disease outcome in C9orf72 long expansion carriers