Design of Block Transceivers with Decision Feedback Detection

This paper presents a method for jointly designing the transmitter-receiver pair in a block-by-block communication system that employs (intra-block) decision feedback detection. We provide closed-form expressions for transmitter-receiver pairs that simultaneously minimize the arithmetic mean squared error (MSE) at the decision point (assuming perfect feedback), the geometric MSE, and the bit error rate of a uniformly bit-loaded system at moderate-to-high signal-to-noise ratios. Separate expressions apply for the ``zero-forcing'' and ``minimum MSE'' (MMSE) decision feedback structures. In the MMSE case, the proposed design also maximizes the Gaussian mutual information and suggests that one can approach the capacity of the block transmission system using (independent instances of) the same (Gaussian) code for each element of the block. Our simulation studies indicate that the proposed transceivers perform significantly better than standard transceivers, and that they retain their performance advantages in the presence of error propagation.Comment: 14 pages, 8 figures, to appear in the IEEE Transactions on Signal Processin

Post-Hierarchical Race: Reconsidering the Nature of Hierarchy within Haslanger's Account of Race

In this essay, I consider Sally Haslanger’s social constructivist account of race and propose a modification to the nature of hierarchy specified. According to Haslanger, race will cease to exist post-hierarchy, given that she builds in a requirement of synchronic hierarchy for the existence of race. While Haslanger maintains that racial identity would linger beyond hierarchical treatment in the form of ethnicity, I will suggest this fails to provide adequate conceptual justice for the cultures and aesthetics which emerged out of past oppression. In response, I propose a modification which would allow us to recognize the possibility of post-hierarchical races

Development of the text of the Ramsar Convention: 1965–1971

The ‘Ramsar’ Convention on Wetlands was the first of the modern era global biodiversity conventions and remains the only multilateral environmental agreement focused on a single group of ecosystem types. At the time of initial discussions within the wetland conservation science community in the late 1960s, its ambition was unprecedented, with no successful models to draw upon, especially with regard to novel concepts such as the modus for an ‘internationally protected site’. Drawing on previously unpublished draft texts, we track the Convention’s textual development to its ultimate agreement in 1971. During this period its geographic scope changed from an initial European to global focus, whereas core obligations related to the designation of internationally important wetlands and the provision of secretariat coordination functions were substantively developed. We present (as supplementary material) all draft texts, from 1965 to 1971, previously unavailable online

Uniform decomposition of mutual information using MMSE decision feedback detection

Abstract-We consider efficient techniques for the design of a transceiver for a matrix channel with minimum mean square error (MMSE) decision-feedback (DF) detection when perfect channel information is available at both the transmitter and receiver. By combining the canonical property of the MMSE-DF detector and our recently developed equal-diagonal QRS decomposition of a matrix we obtain a uniform decomposition of mutual information in which each of the synthesized scalar subchannels has the same mutual information (under the assumption of error-free feedback). To assist our analysis of this uniform decomposition, we provide a new QR interpretation of the MMSE-DF receiver. This enables us to show that the natural detection order is optimal (in an SINR sense), and that for the proposed transmitter, the MMSE-DF detector is asymptotically equivalent to the maximum likelihood detector when the SNR is high. We also derive a low-complexity quadratic recursive algorithm for the characterization of all eligible S-factors in the QRS decomposition. When coupled with our QR interpretation of the MMSE-DF detector, this enables us to efficiently design the optimal transmitter and to efficiently implement the MMSE-DF receiver

Transferrinfection. A Highly Efficient Way to Express Gene Constructs in Eukaryotic Cells

No abstract available

Towards a new paradigm of care: the International Declaration on Youth Mental Health.

A recent and growing body of evidence on young people\u27s mental health has pointed to the need for an international response to the increasing and concerning rates of mental ill-health among young people.[1, 2] The periods of adolescence and emerging adulthood[3] are considered the peak periods for the onset of mental ill-health[4] with 75% of all adult diagnoses of mental ill-health having had an onset before the age of 25 years.[5] In an era when the physical health of young people has never been better,[6] their psychological and mental health has never been worse.[7] This leaves young people vulnerable to developing potentially intractable and enduring mental health difficulties with the inevitable personal, familial, social and vocational consequences that accompany the experience of mental ill-health.[4, 8] In spite of growing concerns about young people\u27s mental health, service provision for young people remains largely inadequate and unsuited to their needs. A number of systemic factors can be implicated in insufficient and unsuitable mental health service provision for young people. Internationally, there has been an endemic failure to invest in mental health across the lifespan with an average global spend on mental health of less than $US3 per capita per year.[9] This global underinvestment brings with it particular challenges in relation to the level of priority afforded to youth mental health and the concurrent commitment needed to respond to the scale of young people\u27s mental health needs. Even in developed countries where mental health services exist, there are widespread problems with services targeting young people. Primary care and other front line community agencies can struggle to respond to high levels of need, often with little support from specialist mental health services. Specialist mental health services have traditionally followed a paediatric-adult split, with child and adolescent services offering intervention until the largely arbitrary ages of 16 or 18 years and adult services taking all young people 18 years and older.[1] In many instances, there have been gaps in service provision between the ages of 16 and 18 years.[10] This has resulted in many young people being unable to access specialist mental health support during these critical years along with high rates of attrition and dissatisfaction by young people during this transitional period.[11, 12] With a recognition that, in many sociocultural contexts, the transition from adolescence to adulthood is a variable one that spans a period from the mid-teens to the mid- to late-20s,[13] both young people and youth mental health advocates have called for a reorganization of mental health services to mirror this extended developmental period for young people.[2] Not surprisingly, there has been a trend of poor help seeking and engagement by young people in mental health services.[14, 15] A key challenge remains in supporting young people to reach out for help when they need it and early evidence suggests that factors such as ease of access, the physical environment, location, atmosphere, branding and peer influence can promote help seeking among young people.[12] It must be noted, however, that even when services are youth friendly and appropriate to their needs, individual and psychological factors strongly influence help-seeking behaviour among young people experiencing emotional or psychological distress.[16, 17] From both an economic[18] and a human impact perspective, there is a strong rationale to invest in efforts to tackle the reality of mental ill-health among the youth population.[2] Efforts to establish a new youth mental health paradigm have already begun and are gaining momentum internationally, reflected most recently in the establishment of a new International Association for Youth Mental Health (http://www.iaymh.org). The first International Youth Mental Health Conference was held in Melbourne, Australia, in 2010 and the second is being held in 2013 in Brighton, the UK (http://www.iaymh2013.com). Those involved in the youth mental health movement recognize that positively impacting on young people\u27s mental health trajectories requires transformative change. Along with a need for early promotion, detection and intervention, stemming the tide of mental ill-health among young people requires a fundamental change in how we think about young people and their mental health. It demands that we challenge traditional approaches to service development and delivery and replace them with approaches that are inclusive and empowering for young people and their families. Young people and their families need to be involved in designing and implementing more creative, responsive, accessible and youth-friendly mental health services that have the capacity to meet their needs

Predictors of Radiotherapy Induced Bone Injury (RIBI) after stereotactic lung radiotherapy

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to identify clinical and dosimetric factors associated with radiotherapy induced bone injury (RIBI) following stereotactic lung radiotherapy.</p> <p>Methods</p> <p>Inoperable patients with early stage non-small cell lung cancer, treated with SBRT, who received 54 or 60 Gy in 3 fractions, and had a minimum of 6 months follow up were reviewed. Archived treatment plans were retrieved, ribs delineated individually and treatment plans re-computed using heterogeneity correction. Clinical and dosimetric factors were evaluated for their association with rib fracture using logistic regression analysis; a dose-event curve and nomogram were created.</p> <p>Results</p> <p>46 consecutive patients treated between Oct 2004 and Dec 2008 with median follow-up 25 months (m) (range 6 – 51 m) were eligible. 41 fractured ribs were detected in 17 patients; median time to fracture was 21 m (range 7 – 40 m). The mean maximum point dose in non-fractured ribs (n = 1054) was 10.5 Gy ± 10.2 Gy, this was higher in fractured ribs (n = 41) 48.5 Gy ± 24.3 Gy (p < 0.0001). On univariate analysis, age, dose to 0.5 cc of the ribs (D_0.5), and the volume of the rib receiving at least 25 Gy (V₂₅), were significantly associated with RIBI. As D_0.5 and V₂₅ were cross-correlated (Spearman correlation coefficient: 0.57, p < 0.001), we selected D_0.5 as a representative dose parameter. On multivariate analysis, age (odds ratio: 1.121, 95% CI: 1.04 – 1.21, p = 0.003), female gender (odds ratio: 4.43, 95% CI: 1.68 – 11.68, p = 0.003), and rib D_0.5 (odds ratio: 1.0009, 95% CI: 1.0007 – 1.001, p < 0.0001) were significantly associated with rib fracture.</p> <p>Using D_0.5, a dose-event curve was constructed estimating risk of fracture from dose at the median follow up of 25 months after treatment. In our cohort, a 50% risk of rib fracture was associated with a D_0.5 of 60 Gy.</p> <p>Conclusions</p> <p>Dosimetric and clinical factors contribute to risk of RIBI and both should be included when modeling risk of toxicity. A nomogram is presented using D_0.5, age, and female gender to estimate risk of RIBI following SBRT. This requires validation.</p

Connectivity: insights from the U.S. Long Term Ecological Research Network

Ecosystems across the United States are changing in complex and surprising ways. Ongoing demand for critical ecosystem services requires an understanding of the populations and communities in these ecosystems in the future. This paper represents a synthesis effort of the U.S. National Science Foundation-funded Long-Term Ecological Research (LTER) network addressing the core research area of “populations and communities.” The objective of this effort was to show the importance of long-term data collection and experiments for addressing the hardest questions in scientific ecology that have significant implications for environmental policy and management. Each LTER site developed at least one compelling case study about what their site could look like in 50–100 yr as human and environmental drivers influencing specific ecosystems change. As the case studies were prepared, five themes emerged, and the studies were grouped into papers in this LTER Futures Special Feature addressing state change, connectivity, resilience, time lags, and cascading effects. This paper addresses the “connectivity” theme and has examples from the Phoenix (urban), Niwot Ridge (alpine tundra), McMurdo Dry Valleys (polar desert), Plum Island (coastal), Santa Barbara Coastal (coastal), and Jornada (arid grassland and shrubland) sites. Connectivity has multiple dimensions, ranging from multi-scalar interactions in space to complex interactions over time that govern the transport of materials and the distribution and movement of organisms. The case studies presented here range widely, showing how land-use legacies interact with climate to alter the structure and function of arid ecosystems and flows of resources and organisms in Antarctic polar desert, alpine, urban, and coastal marine ecosystems. Long-term ecological research demonstrates that connectivity can, in some circumstances, sustain valuable ecosystem functions, such as the persistence of foundation species and their associated biodiversity or, it can be an agent of state change, as when it increases wind and water erosion. Increased connectivity due to warming can also lead to species range expansions or contractions and the introduction of undesirable species. Continued long-term studies are essential for addressing the complexities of connectivity. The diversity of ecosystems within the LTER network is a strong platform for these studies