Modeling the partially coherent behavior of few-mode far-infrared grating spectrometers

Modelling ultra-low-noise far-infrared grating spectrometers has become crucial for the next generation of far-infrared space observatories. Conventional techniques are awkward to apply because of the partially coherent form of the incident spectral field, and the few-mode response of the optics and detectors. We present a modal technique for modelling the behaviour of spectrometers, which allows for the propagation and detection of partially coherent fields, and the inclusion of straylight radiated by warm internal surfaces. We illustrate the technique by modelling the behaviour of the Long Wavelength Band of the proposed SAFARI instrument on the well-studied SPICA mission.Comment: This paper is submitted to Journal Optical Society of America A. When accepted, the paper can be found here: https://opg.optica.org/josaa/home.cf

Occupational therapy for community dwelling elderly people: a systematic review

OBJECTIVE: Occupational therapy might play an important role in maintaining independent living for community dwelling elderly people. The aim of this systematic review is to determine whether occupational therapy improves outcome for people who are >/=60 years and are living independently. METHODS: An extensive search in MEDLINE, CINAHL, EMBASE, AMED and SCISEARCH until July 2002 was performed. Studies with controlled and uncontrolled designs were included. Six intervention categories were distinguished and individually analysed using a best-evidence synthesis, based on the type of design, the methodological quality, type of outcome measures and statistical significance of findings. RESULTS: 17 studies were included, ten of which were randomised clinical trials. Six randomised clinical trials had a high methodological quality. Strong evidence is present for the efficacy of advising on assistive devices as part of a home hazards assessment on functional ability. There is some evidence for the efficacy of training of skills combined with a home hazard assessment in decreasing the incidence of falls in elderly people at high risk of falling. Some evidence is available for the efficacy of comprehensive occupational therapy on functional ability, social participation and quality of life. Insufficient evidence is present for the efficacy of counselling the primary caregiver of dementia patients about maintaining the patient's functional abilities. CONCLUSION: This review shows that occupational therapy interventions for community dwelling elderly people results in positive outcomes. Future research in the efficacy of occupational therapy in elderly patient groups such as people with dementia is recommended. Furthermore, research into tailoring interventions to the needs of elderly patients is recommended. (aut.ref.

Atypical emotional anticipation in high-functioning autism

"Background: Understanding and anticipating others’ mental or emotional states relies on the processing of social cues, such as dynamic facial expressions. Individuals with high-functioning autism (HFA) may process these cues differently from individuals with typical development (TD) and purportedly use a ‘mechanistic’ rather than a ‘mentalistic’ approach, involving rule- and contingency-based interpretations of the stimuli. The study primarily aimed at examining whether the judgments of facial expressions made by individuals with TD and HFA would be similarly affected by the immediately preceding dynamic perceptual history of that face. A second aim was to explore possible differences in the mechanisms underpinning the perceptual judgments in the two groups. Methods: Twenty-two adults with HFA and with TD, matched for age, gender and IQ, were tested in three experiments in which dynamic, ‘ecologically valid’ offsets of happy and angry facial expressions were presented. Participants evaluated the expression depicted in the last frame of the video clip by using a 5-point scale ranging from slightly angry via neutral to slightly happy. Specific experimental manipulations prior to the final facial expression of the video clip allowed examining contributions of bottom-up mechanisms (sequential contrast/ context effects and representational momentum) and a top-down mechanism (emotional anticipation) to distortions in the perception of the final expression. Results: In experiment 1, the two groups showed a very similar perceptual bias for the final expression of joy-to-neutral and anger-to-neutral videos (overshoot bias). In experiment 2, a change in the actor’s identity during the clip removed the bias in the TD group, but not in the HFA group. In experiment 3, neutral-to-joy/anger-to-neutral sequences generated an undershoot bias (opposite to the overshoot) in the TD group, whereas no bias was observed in the HFA group. Conclusions: We argue that in TD individuals the perceptual judgments of other’s facial expressions were underpinned by an automatic emotional anticipation mechanism. In contrast, HFA individuals were primarily influenced by visual features, most notably the contrast between the start and end expressions, or pattern extrapolation. We critically discuss the proposition that automatic emotional anticipation may be induced by motor simulation of the perceived dynamic facial expressions and discuss its implications for autism.

Full characterization and analysis of a terahertz heterodyne receiver based on a NbN hot electron bolometer

We present a complete experimental characterization of a quasioptical twin-slot antenna coupled small area (1.0×0.15 µm^2) NbN hot electron bolometer (HEB) mixer compatible with currently available solid state tunable local oscillator (LO) sources. The required LO power absorbed in the HEB is analyzed in detail and equals only 25 nW. Due to the small HEB volume and wide antenna bandwidth, an unwanted direct detection effect is observed which decreases the apparent sensitivity. Correcting for this effect results in a receiver noise temperature of 700 K at 1.46 THz. The intermediate frequency (IF) gain bandwidth is 2.3 GHz and the IF noise bandwidth is 4 GHz. The single channel receiver stability is limited to 0.2–0.3 s in a 50 MHz bandwidth

Complex Beam Mapping and Fourier Optics Analysis of a Wide-Field Microwave Kinetic Inductance Detector Camera

For astronomical instruments, accurate knowledge of the optical pointing and coupling are essential to characterize the alignment and performance of (sub-)systems prior to integration and deployment. Ideally, this requires the phase response of the optical system, which for direct (phase insensitive) detectors was not previously accessible. Here we show development of the phase sensitive complex beam pattern technique using a dual optical source heterodyne technique for a large field of view Microwave Kinetic Inductance Detector camera at 350 GHz. We show here how you can analyze the measured data with Fourier optics, which allows integration into a telescope model to calculate the on sky beam pattern and telescope aperture efficiency prior to deployment at a telescope.Comment: This is a post-peer-review, pre-copy edit version of an article published in Journal of Low Temperature Physics. The final authenticated version is available onlin

Modal Analysis and Experimental Study of High-Order Mode Contribution to Standing Waves in Quasi-Optical Systems

In many submillimeter-wave optical systems performance is in some way affected by the presence of standing waves. Usually these effects are studied empirically or only modeled to first-order by assuming a quasi-sinusoidal variation with distance and wavelength. In this paper we present an analytical technique to calculate the coupling between two corrugated horns including the total transmission and reflection properties. In our model we have combined the waveguide mode matching technique with a Gaussian beam mode description of the free space propagation. We illustrate the approach for the case of two coupled corrugated horns as the distance between them is varied. We furthermore present experimental test results confirming that multiple reflections do not always result in a classical periodic standing wave pattern. In particular when the horns are close together and the fields are not well matched, high Q cavity effects are observed resulting in irregular standing wave patterns. These cavity effects can be attributed to high-order modes which get trapped between transmitting and receiving horn. We finally discuss the consequences of our observations for a few examples of typical quasi-optical arrangements illustrating that the presented effects can have important consequences for submillimeter-wave optical systems

Increasing condom use in heterosexual men: development of a theory-based interactive digital intervention

Increasing condom use to prevent sexually transmitted infections is a key public health goal. Interventions are more likely to be effective if they are theory- and evidence-based. The Behaviour Change Wheel (BCW) provides a framework for intervention development. To provide an example of how the BCW was used to develop an intervention to increase condom use in heterosexual men (the MenSS website), the steps of the BCW intervention development process were followed, incorporating evidence from the research literature and views of experts and the target population. Capability (e.g. knowledge) and motivation (e.g. beliefs about pleasure) were identified as important targets of the intervention. We devised ways to address each intervention target, including selecting interactive features and behaviour change techniques. The BCW provides a useful framework for integrating sources of evidence to inform intervention content and deciding which influences on behaviour to target