4,603 research outputs found
The effects of selected modern technological concepts on the performance and handling characteristics of LTA vehicles
The results of an airship design sensitivity study are presented. A wide variety of airship design concepts, including the classical and high aero-lift augmented-hybrids are examined with regard to specific technological improvements, and consequent gains in performance, stability and control and flying qualities. Variations in size, payload, power required and airspeed are quantitatively analyzed for airships representing aero-to-buoyant lift ratios of zero to 3.0 over a range of technology improvements implying reduced drag, reduced structural weight fractions and lighter, more efficient propulsion systems. Qualitatively, future airships are discussed in terms of stability, control and flying qualities requirements dictated by projected demands for vastly improved operational effectiveness and ease of handling. Such topics include stability augmentation systems, load-alleviation systems and total computer state-sensing and controls management systems. It was shown that, for the most part, highly refined conventional designs offer attractive gains in both performance and ease of handling. Hybrid airships represent a good potential for missions requiring the transport of heavy payloads at higher airspeeds over shorter ranges without the capability for sustained hover and vertical flight
Content-prioritised video coding for British Sign Language communication.
Video communication of British Sign Language (BSL) is important for remote interpersonal communication and for the equal provision of services for deaf people. However, the use of video telephony and video conferencing applications for BSL communication is limited by inadequate video quality. BSL is a highly structured, linguistically complete, natural language system that expresses vocabulary and grammar visually and spatially using a complex combination of facial expressions (such as eyebrow movements, eye blinks and mouth/lip shapes), hand gestures, body movements and finger-spelling that change in space and time. Accurate natural BSL communication places specific demands on visual media applications which must compress video image data for efficient transmission. Current video compression schemes apply methods to reduce statistical redundancy and perceptual irrelevance in video image data based on a general model of Human Visual System (HVS) sensitivities. This thesis presents novel video image coding methods developed to achieve the conflicting requirements for high image quality and efficient coding. Novel methods of prioritising visually important video image content for optimised video coding are developed to exploit the HVS spatial and temporal response mechanisms of BSL users (determined by Eye Movement Tracking) and the characteristics of BSL video image content. The methods implement an accurate model of HVS foveation, applied in the spatial and temporal domains, at the pre-processing stage of a current standard-based system (H.264). Comparison of the performance of the developed and standard coding systems, using methods of video quality evaluation developed for this thesis, demonstrates improved perceived quality at low bit rates. BSL users, broadcasters and service providers benefit from the perception of high quality video over a range of available transmission bandwidths. The research community benefits from a new approach to video coding optimisation and better understanding of the communication needs of deaf people
The Use of Peripheral Blood-Mononuclear Cells in Scleroderma Patients: An Observational Preliminary Study
Introduction: Systemic sclerosis (SSc) is a systemic autoimmune
disease characterized by vasculopathy and excessive production
of collagen, which lead to skin and visceral fibrosis. The aim of our
study is to assess the potential benefits of autologous peripheral
blood mononuclear cells (PBMCs) implants in the treatment of clinical
manifestations such as mouth impairment, hand disability, digital ulcers
and Raynaud’s phenomenon in Scleroderma patients.
Methods: From February 2016 to May 2019, 10 female patients
were enrolled from the outpatient clinic of the Plastic Surgery Unit of
Sapienza University of Rome. Parameters evaluated were: patients’
disability, using the Health Assessment Questionnaire (HAQ) disability
index (DI) and the scleroderma HAQ (sHAQ); mouth opening capacity, by
measuring the maximum interincisal distance and the mouth perimeter;
hand mobility, assessed with clinical exam and the Hand Mobility in
Scleroderma (HAMIS) scale; Raynaud’s phenomenon, evaluated through
nailfold capillaroscopy; digital ulcers, examined through their features
and incidence of appearance. SPSS software was used for a simple
descriptive statistical analysis performed by the Student’s paired t-test.
P values less than 0.05 were considered statistically significant.
Results: The treatment showed a significant improvement of all
the parameters evaluated at 1-year follow-up, it was well-tolerated by
all the patients and the only complications noticed were small areas of
ecchymosis.
Conclusions: With our preliminary study we tought to exploit PBMCs
capability to induce angiogenesis widely described in literature in order
to treat the vasculopathy-related manifestations of SSc, in patients with
no chance for lipofilling. Our results suggest that PBMCs injection could
represent a treatment option to take into account for SSc patients. The
procedure we used is easy and fast to perform, minimally invasive and
not-operator dependent. We hope our observational and preliminary
study could be considered as a starting point for further research studies
Applying psychological science to the CCTV review process: a review of cognitive and ergonomic literature
As CCTV cameras are used more and more often to increase security in communities, police are spending a larger proportion of their resources, including time, in processing CCTV images when investigating crimes that have occurred (Levesley & Martin, 2005; Nichols, 2001). As with all tasks, there are ways to approach this task that will facilitate performance and other approaches that will degrade performance, either by increasing errors or by unnecessarily prolonging the process. A clearer understanding of psychological factors influencing the effectiveness of footage review will facilitate future training in best practice with respect to the review of CCTV footage. The goal of this report is to provide such understanding by reviewing research on footage review, research on related tasks that require similar skills, and experimental laboratory research about the cognitive skills underpinning the task. The report is organised to address five challenges to effectiveness of CCTV review: the effects of the degraded nature of CCTV footage, distractions and interrupts, the length of the task, inappropriate mindset, and variability in people’s abilities and experience. Recommendations for optimising CCTV footage review include (1) doing a cognitive task analysis to increase understanding of the ways in which performance might be limited, (2) exploiting technology advances to maximise the perceptual quality of the footage (3) training people to improve the flexibility of their mindset as they perceive and interpret the images seen, (4) monitoring performance either on an ongoing basis, by using psychophysiological measures of alertness, or periodically, by testing screeners’ ability to find evidence in footage developed for such testing, and (5) evaluating the relevance of possible selection tests to screen effective from ineffective screener
Delineating Phenotypes of Rare Disease
Not available
Proximity and gaze influences facial temperature:a thermal infrared imaging study
Direct gaze and interpersonal proximity are known to lead to changes in psycho-physiology, behaviour and brain function. We know little, however, about subtler facial reactions such as rise and fall in temperature, which may be sensitive to contextual effects and functional in social interactions. Using thermal infrared imaging cameras 18 female adult participants were filmed at two interpersonal distances (intimate and social) and two gaze conditions (averted and direct). The order of variation in distance was counterbalanced: half the participants experienced a female experimenter’s gaze at the social distance first before the intimate distance (a socially ‘normal’ order) and half experienced the intimate distance first and then the social distance (an odd social order). At both distances averted gaze always preceded direct gaze. We found strong correlations in thermal changes between six areas of the face (forehead, chin, cheeks, nose, maxilliary and periorbital regions) for all experimental conditions and developed a composite measure of thermal shifts for all analyses. Interpersonal proximity led to a thermal rise, but only in the ‘normal’ social order. Direct gaze, compared to averted gaze, led to a thermal increase at both distances with a stronger effect at intimate distance, in both orders of distance variation. Participants reported direct gaze as more intrusive than averted gaze, especially at the intimate distance. These results demonstrate the powerful effects of another person’s gaze on psycho-physiological responses, even at a distance and independent of context
A BIASED COMPETITION COMPUTATIONAL MODEL OF SPATIAL AND OBJECT-BASED ATTENTION MEDIATING ACTIVE VISUAL SEARCH
A computational cognitive neuroscience approach was used to examine processes of visual attention in the human and
monkey brain. The aim of the work was to produce a biologically plausible neurodynamical model of both spatial and
object-based attention that accounted for observations in monkey visual areas V4, inferior temporal cortex (IT) and the
lateral intraparietal area (LIP), and was able to produce search scan path behaviour similar to that observed in humans
and monkeys.
Of particular interest currently in the visual attention literature is the biased competition hypothesis (Desimone &
Duncan. 1995). The model presented here is the first active vision implementation of biased competition, where
attcntional shifts are overt. Therefore, retinal inputs change during the scan path and this approach raised issues, such as
memory for searched locations across saccades, not addressed bv previous models with static retinas.
This is the first model to examine the different time courses associated with spatial and object-based effects at the cellular
level. Single cell recordings in areas V4 (Luck et al., 1997; Chelazzi et al., 2001) and IT (Chelazzi ct al., 1993, 1998)
were replicated such that attentional effects occurred at the appropriate time after onset of the stimulus. Object-based
effects at the cellular level of the model led to systems level behaviour that replicated that observed during active visual
search for orientation and colour feature conjunction targets in psychophysical investigations. This provides a valuable
insight into the link between cellular and system level behaviour in natural systems. At the systems level, the simulated
search process showed selectivity in its scan path that was similar to that observed in humans (Scialfa & Joffe, 1998;
Williams & Reingold, 2001) and monkeys (Motter & Belky. 1998b), being guided to target coloured locations in
preference to locations containing the target orientation or blank areas. A connection between the ventral and dorsal
visual processing streams (Ungerleider & Mishkin. 1982) is suggested to contribute to this selectivity and priority in the
featural guidance of search. Such selectivity and avoidance of blank areas has potential application in computer vision
applications.
Simulation of lesions within the model and comparison with patient data provided further verification of the model.
Simulation of visual neglect due to parietal cortical lesion suggests that the model has the capability to provide insights
into the neural correlates of the conscious perception of stimuli
The biased competition approach described here provides an extendable framework within which further "bottom-up"
stimulus and "top-down" mnemonic and cognitive biases can be added, in order to further examine exogenous versus
endogenous factors in the capture of attention
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