Developments in Directional Modulation Technology

Directional modulation (DM), as a promising physical-layer security technique, is able to secure wireless communications by virtue of the property of its direction-dependent signal modulation format transmission. Here modulated signal waveform signatures can only be detected by legitimate receiver(s) positioned along a-prior assigned directions. This paper reviews the development in DM technology over recent years, and provides some recommendations for future studies.

Design of an automated solar concentrator for the pyrolysis of scrap rubber

An automated solar reactor system was designed and built to carry out catalytic pyrolysis of scrap rubber tires at 550°C. To maximize solar energy concentration, a two degrees-of-freedom automated sun tracking system was developed and implemented. Both the azimuth and zenith angles were controlled via feedback from six photo-resistors positioned on a Fresnel lens. The pyrolysis of rubber tires was tested with the presence of two types of acidic catalysts, H-beta and H-USY. Additionally, a photoactive TiO<inf>2</inf> catalyst was used and the products were compared in terms of gas yields and composition. The catalysts were characterized by BET analysis and the pyrolysis gases and liquids were analyzed using GC-MS. The oil and gas yields were relatively high with the highest gas yield reaching 32.8% with H-beta catalyst while TiO<inf>2</inf> gave the same results as thermal pyrolysis without any catalyst. In the presence of zeolites, the dominant gasoline-like components in the gas were propene and cyclobutene. The TiO<inf>2</inf> and non-catalytic experiments produced a gas containing gasoline-like products of mainly isoprene (76.4% and 88.4% respectively). As for the liquids they were composed of numerous components spread over a wide distribution of C<inf>10</inf> to C<inf>29</inf> hydrocarbons of naphthalene and cyclohexane/ene derivatives.

Infrequent Expression of the Cancer-Testis Antigen, PASD1, in Ovarian Cancer

Ovarian cancer is very treatable in the early stages of disease; however, it is usually detected in the later stages, at which time, treatment is no longer as effective. If discovered early (Stage I), there is a 90% chance of five-year survival. Therefore, it is imperative that early-stage biomarkers are identified to enhance the early detection of ovarian cancer. Cancer-testis antigens (CTAs), such as Per ARNT SIM (PAS) domain containing 1 (PASD1), are unique in that their expression is restricted to immunologically restricted sites, such as the testis and placenta, which do not express MHC class I, and cancer, making them ideally positioned to act as targets for immunotherapy as well as potential biomarkers for cancer detection where expressed. We examined the expression of PASD1a and b in a number of cell lines, as well as eight healthy ovary samples, eight normal adjacent ovarian tissues, and 191 ovarian cancer tissues, which were predominantly stage I (n = 164) and stage II (n = 14) disease. We found that despite the positive staining of skin cancer, only one stage Ic ovarian cancer patient tissue expressed PASD1a and b at detectable levels. This may reflect the predominantly stage I ovarian cancer samples examined. To examine the restriction of PASD1 expression, we examined endometrial tissue arrays and found no expression in 30 malignant tumor tissues, 23 cases of hyperplasia, or 16 normal endometrial tissues. Our study suggests that the search for a single cancer-testes antigen/biomarker that can detect early ovarian cancer must continue.

To fasten words again to visible – and invisible – things

In this extended introductory essay, Catherine Gander and Sarah Garland suggest new ways of looking at the correspondences between visual and verbal practices to consider their material and conceptual connections in a specifically American set of histories, contexts and interpretive traditions. Tracing a lineage of experiential philosophy that is grounded in the overturning of a Cartesian mind/body split, the authors argue for pluralistic perspectives on intermedial innovations that situate embodied and imaginative reader-viewer response as vital to the life of the artwork. Gander and Garland chart two main strands to this approach: the pragmatist strain of American aesthetics and social politics, rooted in the essays of transcendentalist Ralph Waldo Emerson and emanating from the writings of John Dewey and William James; and the conceptualist strain of French-American Marcel Duchamp, whose ground-breaking ideas both positioned the artwork as a phenomenological construction and liberated the artist from established methods of practice and discourse. The ‘imagetext’ (after W. J. T. Mitchell) is therefore, argue Gander and Garland, a site consisting of far more than word and image – but a living assemblage of language, idea, thing, cognition, affect and shared experience.

A Local Superlens

Superlenses enable near-field imaging beyond the diffraction limit. However, their widespread implementation in optical imaging technology so far has been limited by large-scale fabrication, fixed lens position and specific object materials. Here, we demonstrate that a dielectric lamella of sub-wavelength size in all three spatial dimensions behaves as a compact superlens that operates at infrared wavelengths and can be positioned to image any local microscopic area of interest on the sample. In particular, the lamella superlens may be placed in contact with any type of object and therefore enables examination of hard-to-scan samples e.g. with high topography or in liquids, without altering the specimen design. This lamella-based local superlens design is directly applicable to sub-wavelength light-based technology such as integrated optics.

Extreme Loads on an Oscillating Wave Surge Converter

A major difficulty in the design of full scale Wave Energy Converters is the need to design for two conflicting design criteria. In one instance devices must be designed to couple heavily to the incident wave force resulting in the efficient extraction of energy in small sea states, however devices must also be capable of withstanding the harsh conditions encountered during extreme seas. This paper presents an initial investigation of the extreme wave loading of a generic, surface-piercing, pitching flap-type device deployed in near shore wave conditions. Slamming of the flap is selected as the extreme load event for further investigation and the experimental methodologies employed are described. Preliminary results showing both local and global loading under such events are presented for the case of a flap tested in a 3-dimensional environment. Results are presented which show flap slamming effects on the pressures experienced on the front face of the flap.

Signal Reliability Improvement Using Selection Combining Based Macro-Diversity for Off-Body Communications At 868 MHz

This paper investigates the potential improvement in signal reliability for outdoor short-range off-body communications channels at 868 MHz using the macro-diversity offered by multiple co-located base stations. In this study, ten identical hypothetical base stations were positioned equidistantly around the perimeter of a rectangle of length 6.67 m and width 3.3 m. A body worn node was placed on the central chest region of an adult male. Five scenarios, each considering different user trajectories, were then analyzed to test the efficacy of using macro-diversity when the desired link is subject to shadowing caused by the human body. A number of selection combining based macro-diversity configurations consisting of four and then ten base stations were considered. It was found that using a macro-diversity system consisting of four base stations (or equivalently signal branches), a maximum diversity gain of 22.5 dB could be obtained while implementing a 10-base station setup this figure could be improved to 25.2 dB.

Fading Characteristics of Body–to–Body Channels Subject to Vehicular Traffic Conditions at 2.45 GHz

In this paper we investigate the small-scale fading characteristics of body-to-body communications channels in an urban environment at 2.45 GHz. The experiments considered body-to-body channels between devices positioned on two persons on either side of a busy road. The Ricean-K factors estimated from the measurements suggest that a significant dominant component existed in the majority of the channels.

Simultaneous Measurements of the Channel Response for Multiple Eavesdroppers Operating in the Vicinity of a Body Area Network at 2.45 GHz

Channel randomness can be exploited to generate secret keys. However, to ensure secrecy, it is necessary that the channel response of any eavesdropping party remain sufficiently de-correlated with that of the legitimate users'. In this paper, we investigate whether such de-correlation occurs for a body area network (BAN) operating in an indoor environment at 2.45 GHz. The hypothetical BAN configuration consisted of two legitimate transceivers, one situated on the user's left wrist and the other on the user's waist. The eavesdroppers were positioned in either a co-located or distributed manner in the area surrounding the BAN user. Using the simultaneous channel response measured at the legitimate BAN nodes and the eavesdropper positions for stationary and mobile scenarios, we analyze the localized correlation coefficient. This allows us to determine if it is possible to generate secret keys in the presence of multiple eavesdroppers in an indoor environment. Our experimental results show that although channel reciprocity was observed for both the stationary and the mobile scenarios, a higher de-correlation between the legitimate users' channels was observed for the stationary case. This indicates that mobile scenarios are better suited for secret key generation.

Preoperative characteristics and compliance with follow-up after trabeculectomy surgery in rural southern China

Purpose: To evaluate preoperative characteristics and follow-up in rural China after trabeculectomy, the primary treatment for glaucoma there. Methods: Patients undergoing trabeculectomy at 14 rural hospitals in Guangdong and Guangxi Provinces and their doctors completed questionnaires concerning clinical and sociodemographic information, transportation, and knowledge and attitudes about glaucoma. Follow-up after surgery was assessed as cumulative score (1 week: 10 points, 2 weeks: 7 points, 1 month: 5 points). Results Among 212 eligible patients, mean preoperative presenting acuity in the operative eye was 6/120, with 61.3% (n=130) blind (≤6/60). Follow-up rates were 60.8% (129/212), 75.9% (161/212) and 26.9% (57/212) at 1 week, 2 weeks and 1 month, respectively. Patient predictors of poor follow-up included elementary education or less (OR=0.37, 95% CI 0.20 to 0.70, p=0.002), believing follow-up was not important (OR=0.62, 95% CI 0.41 to 0.94, p=0.02), lack of an accompanying person (OR=0.14, 95% CI 0.07 to 0.29, p<0.001), family annual income <US$800 (OR=0.28, 95% CI 0.11 to 0.72, p=0.008) and not requiring removal of scleral flap sutures postoperatively (OR=0.11, 95% CI 0.06 to 0.22, p<0.001). Age, sex, employment, travel distance/time/costs, patient preoperative clinical factors and physician factors were unassociated with follow-up. Conclusions: Follow-up after 2 weeks was inadequate to provide optimal clinical care, and surgery is being applied too late to avoid blindness in the majority of patients. Earlier surgery, support for return visits and better explanations of the importance of follow-up are needed. Directing all patients to return for possible scleral flap suture removal may be a valid strategy to improve follow-up.