3G Wideband CDMA : packet-based optimisation for high data-rate downlink transmission

A third generation (3G) of mobile communication systems, based on Wideband CDMA, are intended to offer high-speed packet-based services. Network operators wish to maximise the throughput in the downlink of3G systems, which requires efficient allocation ofresources. This thesis considers the problem ofmaximising throughput in an interference dominated channel. Cooperative broadcasting is a theoretical technique to mitigate this problem. Its implementation in practical systems requires efficient resource allocati.on to maximise the thr(oughput whilst meeting system and user-imposed constramts. A resource allocation approach is presented for implementing cooperative broadcasting. Users are paired and a teclmique for allocating resources between the pair is developed. Then, a method for pairing the users is considered. Simulation results are presented, which show a throughput improvement over existing resource allocation approaches. The problem ofcontrolling the distribution ofrandomly arriving data to meet the resource allocation specifications is examined. A single-threshold buffer is proposed, which requires fewer calculations than an existing double-threshold buffer. Simulation results are presented which show a throughput improvement may be realised, greater than that which would achievable using other rate control schemes. Cooperative broadcasting may lead to transmissions to some users being allocated low power. When full channel infonnation is available at the transmitter, a water filling solution may be used to maximise capacity. However, when combined with buffer management, erasure may result. This erasure may be overcome using an erasure protection code. Such a code is examined. When combined with Turbo coding, ajoint detector may be used for providing error and erasure protection. Analysis ofthis detector shows a lower limit on the error rate, dependent on the probability of erasure. Simulation results show that using this approach the error rate is significantly improved. This code can then be used to increase capacity, whilst achieving low error rates.Imperial Users onl

The interface between Western mental health care and indigenous healing in South Africa: Xhosa psychiatric nurses' views on traditional healers

Xhosa psychiatric nurses stand unique at the interface between Western mental health care and indigenous healing in South Africa. They stem from a cultural history that is embedded within traditional health care discourses and yet are trained and work within a Western psychiatric model. In embodying the intersection between these two paradigms, they are faced with the challenge of making sense of such an amalgamation. These nurses' views are thus valuable in reflecting this intersection and illustrating many of the central concerns that surround it. This study explicates the views of these nurses toward traditional healers and their potential role in mental health care in South Africa. In addition, it illuminates some of the cultural dynamics at work amongst these subjects as they struggle to make sense of their unique cultural position. Using a questionnaire-based methodology, the views of Xhosa psychiatric nurses in a psychiatric hospital in the Eastern Cape, toward traditional healers and their role in mental-health care, were examined. The findings reveal that the vast majority of these nurses believe in traditional cosmology, involve themselves in traditional ritual practices and regularly visit traditional healers as patients. In suggesting ways in which indigenous healing and Western mental health care can work together, 75% of the nurses were in favour of a general referral system between the hospital and traditional healers, most (77%) agreed that certain patients would be better off being treated by both the hospital and traditional healers than they would if they were only being treated by the hospital alone, and 85% of the subjects agreed that patients who are already seeing traditional healers should check if psychiatric medication might help them. These findings indicate that these nurses operate across two healing systems which are at this point not conceptually compatible. This results in deep cultural tension for the nurses. In being entangled in the dialectical tension created in this context, the nurses manage the incongruencies in three general ways: a) Most, in one form or another, incorporate beliefs from both systems into an integrative model, b) some assimilate their cultural belief system into the Western mental health paradigm, throwing off their beliefs in traditional healing, and c) others remain ambivalent in the dialectic between traditional and Western health care discourses. Although this may suggest that these nurses reside within a cultural milieu that is somewhat unhealthy, at another level, in managing and containing the incompatibility between the two systems, these nurses ensure a space for on-going and healthy critique of the underlying assumptions involved in this health care malaise

Revisiting Linking Early Geospatial Documents with Recogito

Recogito is a web-based environment for collaborative semantic annotation. It is open source software, and provides support for working with either text or image documents, including those served via the IIIF protocol. Originally, the tool has been designed for geographic annotation, i.e. the transcription, marking up and geo-resolving of maps and geographical texts (such as itineraries and travel reports) in the context of historical scholarship, e.g. to map or extract data from a source, or to prepare a digital edition. Over time, however, Recogito’s feature set has grown to provide more general annotation functionality, broadening the scope for further potential application areas. Following up from an earlier article we published in e-Perimetron in 2015, in which we first introduced Recogito, this article looks back on the past four years of use and development. We present how Recogito has technologically evolved; how it has been applied in practice in different projects and for different purposes; and how a vibrant user community has sprung up around it that is shaping its further development. The paper also looks forward to some planned next steps, and sets out our future vision for Recogito’s long-term development and sustainability

First results of the SOAP project. Open access publishing in 2010

The SOAP (Study of Open Access Publishing) project has compiled data on the present offer for open access publishing in online peer-reviewed journals. Starting from the Directory of Open Access Journals, several sources of data are considered, including inspection of journal web site and direct inquiries within the publishing industry. Several results are derived and discussed, together with their correlations: the number of open access journals and articles; their subject area; the starting date of open access journals; the size and business models of open access publishers; the licensing models; the presence of an impact factor; the uptake of hybrid open access.Comment: Submitted to PLoS ON

Highlights from the SOAP project survey. What Scientists Think about Open Access Publishing

The SOAP (Study of Open Access Publishing) project has run a large-scale survey of the attitudes of researchers on, and the experiences with, open access publishing. Around forty thousands answers were collected across disciplines and around the world, showing an overwhelming support for the idea of open access, while highlighting funding and (perceived) quality as the main barriers to publishing in open access journals. This article serves as an introduction to the survey and presents this and other highlights from a preliminary analysis of the survey responses. To allow a maximal re-use of the information collected by this survey, the data are hereby released under a CC0 waiver, so to allow libraries, publishers, funding agencies and academics to further analyse risks and opportunities, drivers and barriers, in the transition to open access publishing.Comment: Data manual available at http://bit.ly/gI8nct Compressed CSV data file available at http://bit.ly/gSmm71 Alternative data formats: CSV http://bit.ly/ejuvKO XLS http://bit.ly/e6gE7o XLSX http://bit.ly/gTjyv

Hot high-mass accretion disk candidates

To better understand the physical properties of accretion disks in high-mass star formation, we present a study of a 12 high-mass accretion disk candidates observed at high spatial resolution with the Australia Telescope Compact Array (ATCA) in the NH3 (4,4) and (5,5) lines. Almost all sources were detected in NH3, directly associated with CH3OH Class II maser emission. From the remaining eleven sources, six show clear signatures of rotation and/or infall motions. These signatures vary from velocity gradients perpendicular to the outflows, to infall signatures in absorption against ultracompact HII regions, to more spherical infall signatures in emission. Although our spatial resolution is ~1000AU, we do not find clear Keplerian signatures in any of the sources. Furthermore, we also do not find flattened structures. In contrast to this, in several of the sources with rotational signatures, the spatial structure is approximately spherical with sizes exceeding 10^4 AU, showing considerable clumpy sub-structure at even smaller scales. This implies that on average typical Keplerian accretion disks -- if they exist as expected -- should be confined to regions usually smaller than 1000AU. It is likely that these disks are fed by the larger-scale rotating envelope structure we observe here. Furthermore, we do detect 1.25cm continuum emission in most fields of view.Comment: 21 pages, 32 figures, accepted for ApJS. A high-resolution version can be found at http://www.mpia.de/homes/beuther/papers.htm

Innovation in Deep Space Habitat Interior Design: Lessons Learned From Small Space Design in Terrestrial Architecture

Increased public awareness of carbon footprints, crowding in urban areas, and rising housing costs have spawned a 'small house movement' in the housing industry. Members of this movement desire small, yet highly functional residences which are both affordable and sensitive to consumer comfort standards. In order to create comfortable, minimum-volume interiors, recent advances have been made in furniture design and approaches to interior layout that improve both space utilization and encourage multi-functional design for small homes, apartments, naval, and recreational vehicles. Design efforts in this evolving niche of terrestrial architecture can provide useful insights leading to innovation and efficiency in the design of space habitats for future human space exploration missions. This paper highlights many of the cross-cutting architectural solutions used in small space design which are applicable to the spacecraft interior design problem. Specific solutions discussed include reconfigurable, multi-purpose spaces; collapsible or transformable furniture; multi-purpose accommodations; efficient, space saving appliances; stowable and mobile workstations; and the miniaturization of electronics and computing hardware. For each of these design features, descriptions of how they save interior volume or mitigate other small space issues such as confinement stress or crowding are discussed. Finally, recommendations are provided to provide guidance for future designs and identify potential collaborations with the small spaces design community

Direct detection of a flared disk around a young massive star HD200775 and its 10 to 1000AU scale properties

We made mid-infrared observations of the 10Msun Herbig Be star HD200775 with the Cooled Mid-Infrared Camera and Spectrometer (COMICS) on the 8.2m Subaru Telescope. We discovered diffuse emission of an elliptical shape extended in the north-south direction inabout 1000AU radius around unresolved excess emission. The diffuse emission is perpendicular to the cavity wall formed by the past outflow activity and is parallel to the projected major axis of the central close binary orbit. The centers of the ellipse contours of the diffuse emission are shifted from the stellar position and the amount of the shift increases as the contour brightness level decreases. The diffuse emission is well explained in all of geometry, size, and configuration by an inclined flared disk where only its surface emits the mid-infrared photons. Our results give the first well-resolved infrared disk images around a massive star and strongly support that HD200775 is formed through the disk accretion. The disk survives the main accretion phase and shows a structure similar to that around lower-mass stars with 'disk atmosphere'. At the same time, the disk also shows properties characteristic to massive stars such as photoevaporation traced by the 3.4mm free-free emission and unusual silicate emission with a peak at 9.2micron, which is shorter than that of many astronomical objects. It provides a good place to compare the disk properties between massive and lower-mass stars.Comment: 18 pages, 8 figures, accepted by The Astrophysical Journa