2,478 research outputs found
Britannia in numbers: 50 years of the journal of Romano-British and kindred studies
This paper reviews contributions to the journal Britannia over the last 50 years, and considers future directions. Papers are examined in relation to topic and the gender and professional associations of authors
Proforma-based reporting in rectal cancer
The improvements in outcomes associate with the use of preoperative therapy rather than postoperative treatment means that clinical teams are increasingly reliant on imaging to identify high-risk features of disease to determine treatment plans. For many solid tumours, including rectal cancer, validated techniques have emerged in identifying prognostic factors pre-operatively. In the MERCURY study, a standardised scanning technique and the use of reporting proformas enabled consistently accurate assessment and documentation of the prognostic factors. This is now an essential tool to enable our clinical colleagues to make treatment decisions. In this review, we describe the proforma-based reporting tool that enables a systematic approach to the interpretation of the magnetic resonance images, thereby enabling all the clinically relevant features to be adequately assessed. © 2009 International Cancer Imaging Society
Decomposition of coarse woody debris in a long-term litter manipulation experiment: A focus on nutrient availability
The majority of above-ground carbon in tropical forests is stored in wood, which is returned to the atmosphere during decomposition of coarse woody debris. However, the factors controlling wood decomposition have not been experimentally manipulated over time scales comparable to the length of this process.We hypothesized that wood decomposition is limited by nutrient availability and tested this hypothesis in a long-term litter addition and removal experiment in a lowland tropical forest in Panama. Specifically, we quantified decomposition using a 15-year chronosequence of decaying boles, and measured respiration rates and nutrient limitation of wood decomposer communities.The long-term probability that a dead tree completely decomposed was decreased in plots where litter was removed, but did not differ between litter addition and control treatments. Similarly, respiration rates of wood decomposer communities were greater in control treatments relative to litter removal plots; litter addition treatments did not differ from either of the other treatments. Respiration rates increased in response to nutrient addition (nitrogen, phosphorus, and potassium) in the litter removal and addition treatments, but not in the controls.Established decreases in concentrations of soil nutrients in litter removal plots and increased respiration rates in response to nutrient addition suggest that reduced rates of wood decomposition after litter removal were caused by decreased nutrient availability. The effects of litter manipulations differed directionally from a previous short-term decomposition study in the same plots, and reduced rates of bole decomposition in litter removal plots did not emerge until after more than 6 years of decomposition. These differences suggest that litter-mediated effects on nutrient dynamics have complex interactions with decomposition over time
Longitudinal analysis of the neurological features of ataxia telangiectasia
Aim: To assess the relationship between genotype and neurological progression in ataxiaâtelangiectasia (AâT).
Methods: Clinical and laboratory data were extracted retrospectively from the records of patients attending the UK National AtaxiaâTelangiectasia Clinic. Neurological assessments were performed using the AâT Index (Crawford Score) and the AâT Neurological Examination Scale Toolkit (AâT NEST). Variables influencing phenotype were identified by using an informationâtheoretic approach starting from a maximal model to generate estimates of coefficients for each variable. Perâindividual progression was assessed for patients with three or more clinic attendances.
Results: The genotype could be determined for 125/135 patients. Crawford and AâT NEST scores were well correlated. For both scoring systems the estimated coefficients were significantly positive for Age x kinase activity but not Age x protein expression. Unlike the perâgenotype analysis, the individual progression of neurological scores in the 34 patients that attended on three or more occasions was not smooth and linear (and in some cases improved over time).
Interpretation: Residual kinase activity confers a milder phenotype but there is no difference between kinaseâdead and proteinânull genotypes. The nonâlinear progression of individual patientsâ neurological scores may reflect biological complexity, dayâtoâday variability, limitations of the assessment methods or a combination of all three
Snaking and isolas of localised states in bistable discrete lattices
We consider localised states in a discrete bistable Allen-Cahn equation. This
model equation combines bistability and local cell-to-cell coupling in the
simplest possible way. The existence of stable localised states is made
possible by pinning to the underlying lattice; they do not exist in the
equivalent continuum equation. In particular we address the existence of
'isolas': closed curves of solutions in the bifurcation diagram. Isolas appear
for some non-periodic boundary conditions in one spatial dimension but seem to
appear generically in two dimensions. We point out how features of the
bifurcation diagram in 1D help to explain some (unintuitive) features of the
bifurcation diagram in 2D.Comment: 14 page
Mathematical models of magnetospheric convection and its coupling to the ionosphere
Mathematical models of magnetospheric convection and its coupling to ionospher
Three years of ocean data from a bio-optical profiling float
Ocean color, first measured from space 30 years ago, has provided a revolutionary synoptic view of near-surface fields of phytoplankton pigments. Since 1979, a number of ocean color satellite missions have provided coverage of phytoplankton biomass and other biogeochemical variables on scales of days to years and of kilometers to ocean basin. Because of the nature of visible light and its interaction with absorbing and scattering materials in the ocean and atmosphere, these measurements are biased toward nearsurface waters and are obscured by clouds. As a consequence, ocean color satellites miss significant fractions of phytoplankton biomass, marine primary productivity, and particle flux that occur at depths beyond their sensing range. They also miss phytoplankton blooms and other events that occur during periods of extended cloud cover
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Design of a flexible, user friendly feature matrix generation system and its application on biomedical datasets
© The Author(s) 2020. The generation of a feature matrix is the first step in conducting machine learning analyses on complex data sets such as those containing DNA, RNA or protein sequences. These matrices contain information for each object which have to be identified using complex algorithms to interrogate the data. They are normally generated by combining the results of running such algorithms across various datasets from different and distributed data sources. Thus for non-computing experts the generation of such matrices prove a barrier to employing machine learning techniques. Further since datasets are becoming larger this barrier is augmented by the limitations of the single personal computer most often used by investigators to carry out such analyses. Here we propose a user friendly system to generate feature matrices in a way that is flexible, scalable and extendable. Additionally by making use of The Berkeley Open Infrastructure for Network Computing (BOINC) software, the process can be speeded up using distributed volunteer computing possible in most institutions. The system makes use of a combination of the Grid and Cloud User Support Environment (gUSE), combined with the Web Services Parallel Grid Runtime and Developer Environment Portal (WS-PGRADE) to create workflow-based science gateways that allow users to submit work to the distributed computing. This report demonstrates the use of our proposed WS-PGRADE/gUSE BOINC system to identify features to populate matrices from very large DNA sequence data repositories, however we propose that this system could be used to analyse a wide variety of feature sets including image, numerical and text data
The role of superficial geology in controlling groundwater recharge in the weathered crystalline basement of semi-arid Tanzania
Study region: Little Kinyasungwe River Catchment, central semi-arid Tanzania. Study focus: The structure and hydraulic properties of superficial geology can play a crucial role in controlling groundwater recharge in drylands. However, the pathways by which groundwater recharge occurs and their sensitivity to environmental change remain poorly resolved. Geophysical surveys using Electrical Resistivity Tomography (ERT) were conducted in the study region and used to delineate shallow subsurface stratigraphy in conjunction with borehole logs. Based on these results, a series of local-scale conceptual hydrogeological models was produced and collated to generate a 3D conceptual model of groundwater recharge to the wellfield. New hydrological insights for the region: We propose that configurations of superficial geology control groundwater recharge in dryland settings as follows: 1) superficial sand deposits act as collectors and stores that slowly feed recharge into zones of active faulting; 2) these fault zones provide permeable pathways enabling greater recharge to occur; 3) âwindowsâ within layers of smectitic clay that underlie ephemeral streams may provide pathways for focused recharge via transmission losses; and 4) overbank flooding during high intensity precipitation events increases the probability of activating such permeable pathways. These conceptual models provide a physical basis to improve numerical models of groundwater recharge in drylands, and a conceptual framework to evaluate strategies (e.g., Managed Aquifer Recharge) to artificially enhance the availability of groundwater resources in these regions
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