7,219 research outputs found

    On (t,r) Broadcast Domination Numbers of Grids

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    The domination number of a graph G=(V,E)G = (V,E) is the minimum cardinality of any subset SVS \subset V such that every vertex in VV is in SS or adjacent to an element of SS. Finding the domination numbers of mm by nn grids was an open problem for nearly 30 years and was finally solved in 2011 by Goncalves, Pinlou, Rao, and Thomass\'e. Many variants of domination number on graphs have been defined and studied, but exact values have not yet been obtained for grids. We will define a family of domination theories parameterized by pairs of positive integers (t,r)(t,r) where 1rt1 \leq r \leq t which generalize domination and distance domination theories for graphs. We call these domination numbers the (t,r)(t,r) broadcast domination numbers. We give the exact values of (t,r)(t,r) broadcast domination numbers for small grids, and we identify upper bounds for the (t,r)(t,r) broadcast domination numbers for large grids and conjecture that these bounds are tight for sufficiently large grids.Comment: 28 pages, 43 figure

    The Iron Ore, Coal and Gas Sectors

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    The industrialisation of Asia – particularly China and India – has led to a strong increase in global demand for key resource commodities. The associated sharp rise in the prices of these commodities has underpinned a significant increase in the levels of Australia’s resource investment, production and exports over the past five years, especially for iron ore, coal and liquefied natural gas (LNG). This article outlines some key features and recent developments in these three commodity sectors within Australia.Resource exports; resource capacity; iron ore; coal; LNG

    Long-Term Structural Price Relationships in Real Estate Markets

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    This study investigates the long-run stochastic properties of real estate assets by geographical breakdown. We also study their linkages with financial assets. The initial tests find that almost all property types exhibit the presence of nonstationarity. Thus, cointegrated methodologies are used. Structural breakpoints identified in the literature are used as a guide to divide the data into two windows, 1983-1989 and 1990-1996. The results show that real estate in the different regions exhibit a closer relationship with each other in the second period, compared with the first. Also, strong linkages between real estate regions and financial assets are noted in the second period. The South is the only region to exhibit segmentation in both periods. Overall, the information derived from our analysis sheds light on linkages among real estate assets and between real estate and financial assets and also provides a framework for creating diversified portfolios.

    The role of Melancholia in prostate cancer patients' depression

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    BACKGROUND: Although it is well established that prostate cancer (PCa) patients are more likely to experience clinical depression than their age-matched non-prostate cancer peers, and that such depression can have negative effects upon survival, little is known about the underlying nature of the depressive symptomatology that these men experience. In particular, the incidence of melancholic symptoms of depression, which are signs of increased risk of suicide and resistance to treatment, has not previously been reported in PCa patients. The present study aimed to measure the incidence and nature of Melancholia in PCa depression. METHOD: A sample of 507 PCa patients in Queensland, Australia, completed anonymous and confidential questionnaires about their background, treatment status, and depression. Data were analysed to select depressive symptoms that were part of the definition of Melancholia vs those which were not. Regression was used to determine the links between Melancholia and overall depressive status, and factor analysis revealed the underlying components of Melancholia, which were mapped over time since diagnosis for 3 years. RESULTS: Psychometric data were satisfactory. Melancholia significantly predicted depressive status for the most depressed subset of patients, but not for the total sample. Melancholia was factored into its components of Anhedonia and Agitation, and the first of these was more powerful in predicting Melancholia. Variability over the 3 years following diagnosis was noted for each of these two components of Melancholia. CONCLUSIONS: The strong presence of Melancholia in the depressive symptomatology of this sample of PCa patients suggests that some forms of treatment for depression may be more likely to succeed than others. The dominance of Anhedonia and Agitation over other symptoms of Melancholia also holds implications for treatment options when assisting these men to cope with their depression

    A novel method for estimating myocardial strain: assessment of deformation tracking against reference magnetic resonance methods in healthy volunteers

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    We developed a novel method for tracking myocardial deformation using cardiac magnetic resonance (CMR) cine imaging. We hypothesised that circumferential strain using deformation-tracking has comparable diagnostic performance to a validated method (Displacement Encoding with Stimulated Echoes- DENSE) and potentially diagnostically superior to an established cine-strain method (feature-tracking). 81 healthy adults (44.6 ± 17.7 years old, 47% male), without any history of cardiovascular disease, underwent CMR at 1.5T including cine, DENSE, and late gadolinium enhancement in subjects >45 years. Acquisitions were divided into 6 segments, and global and segmental peak circumferential strain were derived and analysed by age and sex. Peak circumferential strain differed between the 3 groups (DENSE: -19.4 ± 4.8 %; deformation-tracking: -16.8 ± 2.4 %; feature-tracking: -28.7 ± 4.8%) (ANOVA with Tukey post-hoc, F-value 279.93, p<0.01). DENSE and deformation-tracking had better reproducibility than feature-tracking. Intra-class correlation co-efficient was >0.90. Larger magnitudes of strain were detected in women using deformation-tracking and DENSE, but not feature-tracking. Compared with a reference method (DENSE), deformation-tracking using cine imaging has similar diagnostic performance for circumferential strain assessment in healthy individuals. Deformation-tracking could potentially obviate the need for bespoke strain sequences, reducing scanning time and is more reproducible than feature-tracking

    Structure-function analysis of the Bacillus megaterium GerUD spore germinant receptor protein.

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    Germination of Bacillus spores is triggered by the interaction of germinant molecules with specialized receptor proteins localized to the spore inner membrane. Germinant receptors (GRs) are comprised typically of three interacting protein subunits, each of which is essential for receptor function. At least some GRs appear to have a fourth component, referred to as a D-subunit protein. A number of D-subunit proteins were shown previously to be capable of modulating the activity of associated GRs. Here, we investigate the topology and structure-function relationships of the Bacillus megaterium QM B1551 GerUD protein, which is associated with the GerU GR. The presented data demonstrate that GerUD can be subjected to relatively extensive structural modifications while retaining function. Indeed, the presence of either of the two transmembrane spanning domains is sufficient to modulate an efficient GerU-mediated germinative response. The precise function of D-subunit proteins has yet to be established, although they may act as molecular chaperones within the spore inner-membrane environment.S.G was the recipient of a RA Fisher bursary award from Gonville and Caius College, University of Cambridge. X.Z is the recipient of an EPSRC Doctoral Training Grant.This is the final version of the article. It was first available from OUP via http://dx.doi.org/10.1093/femsle/fnv21

    Exploring views on satisfaction with life in young children with chronic illness: an innovative approach to the collection of self-report data from children under 11

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    The objective of this study was to explore young children’s views on the impact of chronic illness on their life in order to inform future development of a patient-based self-report health outcome measure. We describe an approach to facilitating self-report views from young children with chronic illness. A board game was designed in order to obtain qualitative data from 39 children with a range of chronic illness conditions and 38 healthy controls ranging in age from 3 to 11 years. The format was effective in engaging young children in a self-report process of determining satisfaction with life and identified nine domains. The board game enabled children aged 5–11 years with chronic illness to describe the effects of living with illness on home, family, friends, school and life in general. It generated direct, non-interpreted material from children who, because of their age, may have been considered unable or limited their ability to discuss and describe how they feel. Obtaining this information for children aged 4 and under continues to be a challenge

    Feasibility of Manual Teach-and-Replay and Continuous Impedance Shaping for Robotic Locomotor Training Following Spinal Cord Injury

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    Robotic gait training is an emerging technique for retraining walking ability following spinal cord injury (SCI). A key challenge in this training is determining an appropriate stepping trajectory and level of assistance for each patient, since patients have a wide range of sizes and impairment levels. Here, we demonstrate how a lightweight yet powerful robot can record subject-specific, trainer-induced leg trajectories during manually assisted stepping, then immediately replay those trajectories. Replay of the subject-specific trajectories reduced the effort required by the trainer during manual assistance, yet still generated similar patterns of muscle activation for six subjects with a chronic SCI. We also demonstrate how the impedance of the robot can be adjusted on a step-by-step basis with an error-based, learning law. This impedance-shaping algorithm adapted the robot's impedance so that the robot assisted only in the regions of the step trajectory where the subject consistently exhibited errors. The result was that the subjects stepped with greater variability, while still maintaining a physiologic gait pattern. These results are further steps toward tailoring robotic gait training to the needs of individual patients

    Transient Thermal Model and Analysis of the Lunar Surface and Regolith for Cryogenic Fluid Storage

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    A transient thermal model of the lunar surface and regolith was developed along with analytical techniques which will be used to evaluate the storage of cryogenic fluids at equatorial and polar landing sites. The model can provide lunar surface and subsurface temperatures as a function of latitude and time throughout the lunar cycle and season. It also accounts for the presence of or lack of the undisturbed fluff layer on the lunar surface. The model was validated with Apollo 15 and Clementine data and shows good agreement with other analytical models

    A Pilot retrospective analysis of alpha-blockers on recurrence in men with localised prostate cancer treated with radiotherapy

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    While alpha-blockers are commonly used to reduce lower urinary tract symptoms in prostate cancer patients receiving radiotherapy, their impact on response to radiotherapy remains unknown. Therefore, this pilot study aimed to retrospectively determine if alpha-blockers use, influenced response to radiotherapy for localised prostate cancer. In total, 303 prostate cancer patients were included, consisting of 84 control (alpha-blocker naïve), 72 tamsulosin and 147 prazosin patients. The main outcomes measured were relapse rates (%), time to biochemical relapse (months) and PSA velocity (ng/mL/year). Recurrence free survival was calculated using Kaplan-Meier analysis. Prazosin significantly reduced biochemical relapse at both two and five-years (2.72%, 8.84%) compared to control (22.61%, 34.52%). Recurrence free survival was also significantly higher in the prazosin group. This remained after multivariable analysis (HR: 0.09, 95% CI: 0.04–0.26, p < 0.001). Patients receiving prazosin had a 3.9 times lower relative risk of biochemical relapse compared to control. Although not statistically significant, tamsulosin and prazosin extended recurrence free survival by 13.15 and 9.21 months respectively. We show for the first time that prazosin may reduce risk of prostate cancer recurrence and delay time to biochemical relapse and provides justification for prospective studies to examine its potential as an adjunct treatment option for localised prostate cancer.Full Tex
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