290 research outputs found
Upland Heath Swamps Plot Network: Soil Properties, Royal National Park, Sydney Basin, NSW, Australia, 1991+
No full textThe Upland Heath Swamps Plot Network Soil Properties data package for Royal National Park contains soil properties data obtained from samples taken within 10 cm of each of the floristics plots (see Upland Heath Swamps Plot Network: Vegetation Floristics, Royal National Park, Sydney Basin, NSW, Australia, 1990+). A synopsis of related data packages which have been collected as part of the Upland Heath Swamps Plot Network’s full program is provided at http://www.ltern.org.au/index.php/ltern-plot-networks/upland-health-swamps.
**This data package is associated with the following publications:
[1] Letten, A. D., Keith, D. A., Tozer, M. G., Hui, F. K.C. (2015), Fine-scale hydrological niche differentiation through the lens of multi-species co-occurrence models. Journal of Ecology. doi: 10.1111/1365-2745.12428
[2] Keith, D. A. and Bradstock, R. A. (1994). Fire and competition in Australian heath: a conceptual model and field investigations. Journal of Vegetation Science 5, 347-354.
[3] Keith, D. A. (1995a). Mosaics in Sydney heathland vegetation: the roles of fire, competition and soils. CALMScience Supplement 4, 199-206.
[4] Keith, D. A., Lindenmayer, D. B., Lowe, A.,Russell-Smith, J.,Barrett, S.,Enright N. J., Fox, B. J.,Guerin, G.,Paton, D. C., Tozer, M. G. and Yates, C. J. (2014). Heathlands. In: Biodiversity and Environmental Change: Monitoring, Challenges and Direction. Lindenmayer, D., Burns, E., Thurgate, N., and Lowe, A. Editors, pp215-285. CSIRO, Melbourne
Upland Heath Swamps Plot Network: Vegetation Floristics, Royal National Park, Sydney Basin, NSW, Australia, 1990+
No full textThe Upland Heath Swamps Plot Network Vegetation Floristics data package for Royal National Park contains information on the herbaceous species present in permanent plots arranged in eight 30 metre transects. These sites were originally established in 1990, and then sampled annually until 1994, and subsequently in 1999, 2001, 2007, 2011 and 2014. A synopsis of related data packages which have been collected as part of the Upland Heath Swamps Plot Network’s full program is provided at http://www.ltern.org.au/index.php/ltern-plot-networks/upland-health-swamps.
**Note: this data package is associated with the following publications:
[1] Letten, A.D., Keith, D.A. & Tozer, M.G. (2014) Phylogenetic and functional dissimilarity does not increase during temporal heathland succession. Proc. Roy. Soc. B., 281, 20142102–.
[2] Letten, A. D., Keith, D. A., Tozer, M. G., Hui, F. K.C. (2015) Fine-scale hydrological niche differentiation through the lens of multi-species co-occurrence models. Journal of Ecology. doi: 10.1111/1365-2745.12428
[3] Keith, D. A. and Bradstock, R. A. (1994). Fire and competition in Australian heath: a conceptual model and field investigations. Journal of Vegetation Science 5, 347-354.
[4] Keith, D. A. (1995a). Mosaics in Sydney heathland vegetation: the roles of fire, competition and soils. CALMScience Supplement 4, 199-206.
[5] Keith, D. A., Lindenmayer, D. B., Lowe, A.,Russell-Smith, J.,Barrett, S.,Enright N. J., Fox, B. J.,Guerin, G.,Paton, D. C., Tozer, M. G. and Yates, C. J. (2014). Heathlands. In: Biodiversity and Environmental Change: Monitoring, Challenges and Direction. Lindenmayer, D., Burns, E., Thurgate, N., and Lowe, A. Editors, pp215-285. CSIRO, Melbourne
Simple DFT Scheme for Estimating Negative Electron Affinities
No full textA simple density functional theory (DFT) scheme is proposed for estimating negative vertical electron affinities of neutral systems, based on a consideration of the integer discontinuity and density scaling homogeneity. The key feature is the derivation of two system-dependent exchange-correlation functionals, one appropriate for the electron deficient side of the integer and one appropriate for the electron abundant side. The electron affinity is evaluated as a linear combination of frontier orbital energies from self-consistent Kohn–Sham calculations on the neutral system using these functionals. For two assessments comprising a total of 43 molecules, the scheme provides electron affinities that are in good agreement with experimental values and which are an improvement over those from the DFT method of Tozer and De Proft [ J. Phys. Chem. A 2005, 109, 8923]. The scheme is trivial to implement in any Kohn–Sham program, and the computational cost is that of a series of generalized gradient approximation Kohn–Sham calculations. More generally, the study provides a prescription for performing low-cost, self-consistent Kohn–Sham calculations that yield frontier orbital energies that approximately satisfy the appropriate Koopmans conditions, without the need for exact exchange
White and gray matter damage in primary progressive MS: The chicken or the egg?
No full textOBJECTIVE: The temporal relationship between white matter (WM) and gray matter (GM) damage in vivo in early primary progressive multiple sclerosis (PPMS) was investigated testing 2 hypotheses: (1) WM tract abnormalities predict subsequent changes in the connected cortex ("primary WM damage model"); and (2) cortical abnormalities predict later changes in connected WM tracts ("primary GM damage model"). METHODS: Forty-seven patients with early PPMS and 18 healthy controls had conventional and magnetization transfer imaging at baseline; a subgroup of 35 patients repeated the protocol after 2 years. Masks of the corticospinal tracts, genu of the corpus callosum and optic radiations, and of connected cortical regions, were used for extracting the mean magnetization transfer ratio (MTR). Multiple regressions within each of 5 tract-cortex pairs were performed, adjusting for the dependent variable's baseline MTR; tract lesion load and MTR, spinal cord area, age, and sex were examined for potential confounding. RESULTS: The baseline MTR of most regions was lower in patients than in healthy controls. The tract-cortex pair relationships in the primary WM damage model were significant for the bilateral motor pair and right visual pair, while those in the primary GM damage model were only significant for the right motor pair. Lower lesion MTR at baseline was associated with lower MTR in the same tract normal-appearing WM at 2 years in 3 tracts. CONCLUSION: These results are consistent with the hypothesis that in early PPMS, cortical damage is for the most part a sequela of normal-appearing WM pathology, which, in turn, is predicted by abnormalities within WM lesions
A longitudinal study of cortical grey matter lesion subtypes in relapse-onset multiple sclerosis
No full textBackground: Cortical grey matter (GM) lesions are common in multiple sclerosis (MS), but little is known about their temporal evolution. We investigated this in people with relapsing-remitting (RR) and secondary progressive (SP) MS. Methods: 27 people with RRMS, and 22 with SPMS were included in this study. Phase sensitive inversion recovery (PSIR) scans were acquired on two occasions. Cortical GM lesions were classified as intracortical (IC, only involving GM) and leucocortical (LC, mixed GM-white matter [WM]); WM lesions touching the cortex as juxtacortical (JC). On follow up scans, new IC, LC and JC lesions were identified, and any change in classification of lesions previously observed was noted. WM lesion counts in the whole brain were assessed on PD/T2-weighted scans. Results: Over a mean (SD) of 21.0 (5.8) months, the number of new IC lesions per person per year was greater in SPMS (1.6 [1.9]) than RRMS (0.8 [1.9]) (Mann-Whitney p=0.039). All new LC lesions arose from previously seen IC lesions (SPMS 1.4 [1.8] per person per year, and RRMS 1.1 [1.0]), and none arose de novo or from previously seen JC lesions. Changes in cortical GM (either new IC or IC converting to LC) lesion counts did not correlate with the changes in WM lesion counts. Conclusions: New cortical GM lesions rarely arise from the WM and the rate of new IC lesion formation is not closely linked with WM lesion accrual. IC lesion formation appears to be more common in SPMS than RRMS
Atomic electron affinities and the role of symmetry between electron addition and subtraction in a corrected Koopmans approach
No full textThe essential aspects of zero-temperature grand-canonical ensemble density-functional theory are reviewed in the context of spin-density-functional theory and are used to highlight the assumption of symmetry between electron addition and subtraction that underlies the corrected Koopmans approach of Tozer and De Proft (TDP) for computing electron affinities. The issue of symmetry is then investigated in a systematic study of atomic electron affinities, comparing TDP affinities with those from a conventional Koopmans evaluation and electronic energy differences. Although it cannot compete with affinities determined from energy differences, the TDP expression yields results that are a significant improvement over those from the conventional Koopmans expression. Key insight into the results from both expressions is provided by an analysis of plots of the electronic energy as a function of the number of electrons, which highlight the extent of symmetry between addition and subtraction. The accuracy of the TDP affinities is closely related to the nature of the orbitals involved in the electron addition and subtraction, being particularly poor in cases where there is a change in principal quantum number, but relatively accurate within a single manifold of orbitals. The analysis is then extended to a consideration of the ground state Mulliken electronegativity and chemical hardness. The findings further emphasize the key role of symmetry in determining the quality of the results
Concept design of a fast sail assisted feeder container ship
No full textA fast sail assisted feeder container ship concept has been developed for the 2020 container market in the South East Asian and Caribbean regions.The design presented has met the requirements of an initial economic study, with a cargo capacity of 1270 twenty-foot equivalent unit containers, meeting the predictions of container throughput derived from historical data. In determining suitable vessel dimensions, account has also been taken for port and berthing restrictions, and considering hydrodynamic performance. The vessel has been designed for a maximum speed of 25 knots, allowing it to meet the demand for trade whilst reducing the number of ships operating on the routes considered.The design development of the fast feeder concept has involved rigorous analyses in a number of areas to improve the robustness of the final design. Model testing has been key to the development of the concept, by increasing confidence in the final result. This is due to the fact that other analysis techniques are not always appropriate or accurate. Two hull forms have been developed to meet requirements whilst utilising different propulsor combinations. This has enabled evaluation of efficiency gains resulting from different hydrodynamic phenomena for each design. This includes an evaluation of the hydrodynamic performance when utilising the sail system. This has been done using a combination of model test results and data from regression analysis. The final propulsor chosen is a contra-rotating podded drive arrangement. Wind tunnel testing has been used to maximise the performance of a Multi-wing sail system by investigating the effects of wing spacing, stagger and sail-container interactions. This has led to an increase in lift coefficient of 32% from initial predictions. The savings in power requirement due to the sail system are lower than initially predicted. However, another benefit of their installation, motion damping, has been identified. Whilst this has not been fully investigated, additional fuel savings are possible as well as improved seakeeping performance.The design is shown to be environmentally sustainable when compared to existing vessels operating on the proposed routes. This is largely due to the use of low-carbon and zero-sulphur fuel (liquefied natural gas) and improvements in efficiency regarding operation. This especially relates to cargo handling and scheduling. Green house gas emissions have been predicted to fall by 42% and 40% in the two regions should the design be adopted. These savings are also due to the use of the Multi-wing sail system, which contributes to reductions in power requirement of up to 6% when the vessel operates at its lower speed of 15 knots. It is demonstrated that the fast feeder is also economically feasible, with predicted daily cost savings of 27% and 33% in the South East Asian and Caribbean regions respectively. Thus the fast feeder container ship concept is a viable solution for the future of container transhipment. <br/
Detection of Human Bocavirus in respiratory, fecal and blood samples by real-time PCR
No full textHuman bocavirus (HBoV) has been detected worldwide in respiratory samples. Two real-time PCR assays, targeting the non-structural protein (NP-1) and viral protein (VP-1) genes, were designed and validated to detect HBoV in patients with respiratory disease, gastroenteritis, or systemic illness. Sensitivity of the NP-1 and VP-1 assays were equal to the conventional PCR assay previously described by Allander et al, [2005: Proc Natl Acad Sci USA 102: 12891-12896] being 100%, and giving specificity of 94% and 93%, respectively. There was no cross-reaction identified with unrelated respiratory agents, or to human DNA. The limits of detection were 10 copies of genomic DNA equivalents per reaction for both assays. The assays were used to screen three different sample populations, combined nose, and throat swabs (n = 96) from children with acute respiratory disease, fecal samples (n = 375) from adults, and children with gastroenteritis and whole blood (n = 229) collected from 31 immunocompromised children taken over an 18-month period. In total 17 (18%) respiratory samples and 18 (4.8%) fecal samples were identified as having HBoV present. Of the pediatric whole blood specimens investigated, HBoV was detected in six (2.6%) samples from four patients. In summary, two real-time PCR assays targeting different genes were designed and validated for use as screening methods for the detection of HBoV. HBoV was found in three different specimen types: parent-collected combined nose-throat swabs, fecal samples collected from symptomatic individuals and whole blood from immunocompromised children. J. Med. Virol.81:488-493,2009. © 2009 Wiley-Liss, Inc
Evaluation of metadata workflows for the Glasgow ePrints and DSpace services
No full textThe institutional repositories at the University of Glasgow which began as part of the DAEDALUS project have developed into an integral part of Glasgow University Library's services. Using both EPrints.org and DSpace, they provide access to, and permit management of, the University's academic digital assets. This evaluation analyses and comments on the metadata workflows of these services, their support for metadata quality, and how changes in purpose, which have accompanied their transition from project to service, have influenced the repositories. This evaluation will be of benefit not only to DAEDALUS but also to other institutional repositories facing the transition from project development to operational service. The metadata workflows supporting the management and retrieval of ePrints offer a number of paths for metadata creation - each of which has seen shifts in their relative importance as the purpose of the repository has evolved and become clear. The management and retrieval of other academic content in the DSpace service is entirely mediated by repository staff and follows a basic workflow. The quality of metadata in both services has been maintained through staff training and the ongoing involvement of professional cataloguers. The strengths of both repository services lie in their clarity of purpose, utilisation of appropriate software to support those purposes and their successful integration into Glasgow's institutional context. Although they also present a significant opportunity, the new challenges faced by the repository services arise from the emerging involvement of non-specialists in the creation of records and their potential involvement in the administration of sections of the DSpace repository. To address these challenges, the repository services will have to maintain their clarity of purpose, monitor metadata quality, capitalise on opportunities for efficiency, and continue to significantly engage in advocacy and user training
N1s and C1s NEXAFS spectra of model systems for pyridine on Si(100) surface: a DFT simulation
No full textAdsorption of organic molecules on semiconductor surfaces has been attracting a growing attention for its importance in emerging technologies. Since the properties of the resulting materials are largely dependent on the organic/semiconductor interface, fundamental research on the covalent bonding of molecules with the surface can provide useful information. Problems that have been addressed include the structure of the resulting systems and spectroscopic measurements often in concert with theoretical calculations can assess the orientation and geometry of the molecular adsorbate. In this respect NEXAFS spectroscopy represents a powerful technique to investigate the interaction of molecules with a surface. The theoretical simulation of NEXAFS spectra of molecules adsorbed on a surface represents a significant challenge both for a proper modelling of the adsorbate system as well as for the size of system which needs theoretical methods capable to fulfill requirements of accuracy and computational economy. Here we present DFT simulations of NEXAFS spectra of pyridine adsorbed on a regular Si (100) surface, considering several adsorption models.1 The surface and the adsorbate models have been previously optimized through periodic calculations, then suitable finite clusters have been be cut out from the optimized periodic structures and used for the simulation of the angle resolved NEXAFS spectra of the adsorbed molecule. The spectra have been calculated employing a molecular DFT methodology based on the transition potential scheme in order to include the core hole relaxation effect.2 Both the N1s and C1s adsorption edges of the adsorbed pyridine have been investigated. The results show that a careful analysis of the calculated polarized spectra can provide important information on specific details of the adsorbtion geometries; the reliability of the computational strategy is proved by the comparison of the theoretical results with the experimental data.1,3 The periodic optimization of the molecules adsorbed on the surface plays a fundamental role in the design of clusters which correctly model the adsorbed system
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