896 research outputs found
Spectral Type and Radial Velocity Variations in Three SRC Variables
SRC variables are M supergiants, precursors to Type II supernovae, that vary
in brightness with moderately regular periods of order 100-1000 days. Although
identified as pulsating stars that obey their own period-luminosity relation,
few have been examined in enough detail to follow the temperature and spectral
changes that they undergo during their long cycles. The present study examines
such changes for several SRC variables revealed by CCD spectra obtained at the
Dominion Astrophysical Observatory (DAO) during 2005-2009, as well as by
archival spectra from the DAO (and elsewhere) for some stars from the 1960s to
1980s, and Cambridge radial velocity spectrometer measures for Betelgeuse.
Described here is our classification procedure and information on the spectral
type and radial velocity changes in three of the stars. The results provide
insights into the pulsation mechanism in M supergiants.Comment: To appear in the Odessa Variable Stars 2010 conference proceedings
(see http://uavso.org.ua/?page=vs2010), edited by I. Andronov and V. Kovtyuk
Creation of 3D models from large unstructured image and video datasets
Exploration of various places using low-cost camera solutions over decades without having a photogrammetric application in mind has resulted in large collections of images and videos that may have significant cultural value. The purpose of collecting this data is often to provide a log of events and therefore the data is often unstructured and of varying quality. Depending on the equipment used there may be approximate location data available for the images but the accuracy of this data may also be of varying quality. In this paper we present an approach that can deal with these conditions and process datasets of this type to produce 3D models. Results from processing the dataset collected during the discovery and subsequent exploration of the HMAS Sydney and HSK Kormoran wreck sites shows the potential of our approach. The results are promising and show that there is potential to retrieve significantly more information from many of these datasets than previously thought possible
Quantifying methane and nitrous oxide emissions from the UK and Ireland using a national-scale monitoring network
The UK is one of several countries around the world that has enacted legislation to reduce its greenhouse gas emissions. In this study, we present top-down emissions of methane (CH4) and nitrous oxide (N2O) for the UK and Ireland over the period August 2012 to August 2014. These emissions were inferred using measurements from a network of four sites around the two countries. We used a hierarchical Bayesian inverse framework to infer fluxes as well as a set of covariance parameters that describe uncertainties in the system. We inferred average UK total emissions of 2.09 (1.65–2.67) Tg yr−1 CH4 and 0.101 (0.068–0.150) Tg yr−1 N2O and found our derived UK estimates to be generally lower than the a priori emissions, which consisted primarily of anthropogenic sources and with a smaller contribution from natural sources. We used sectoral distributions from the UK National Atmospheric Emissions Inventory (NAEI) to determine whether these discrepancies can be attributed to specific source sectors. Because of the distinct distributions of the two dominant CH4 emissions sectors in the UK, agriculture and waste, we found that the inventory may be overestimated in agricultural CH4 emissions. We found that annual mean N2O emissions were consistent with both the prior and the anthropogenic inventory but we derived a significant seasonal cycle in emissions. This seasonality is likely due to seasonality in fertilizer application and in environmental drivers such as temperature and rainfall, which are not reflected in the annual resolution inventory. Through the hierarchical Bayesian inverse framework, we quantified uncertainty covariance parameters and emphasized their importance for high-resolution emissions estimation. We inferred average model errors of approximately 20 and 0.4 ppb and correlation timescales of 1.0 (0.72–1.43) and 2.6 (1.9–20 3.9) days for CH4 and N2O, respectively. These errors are a combination of transport model errors as well as errors due to unresolved emissions processes in the inventory. We found the largest CH4 errors at the Tacolneston station in eastern England, which may be due to sporadic emissions from landfills and offshore gas in the North Sea
Stepwise basis set selection
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146410/1/jcc25363.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146410/2/jcc25363_am.pd
Predictive indicators for revisional surgery in nasal reconstruction after Mohs surgery
Background: Reconstruction of nasal lesions is complex due to the topography, mobile free margins and borders of anatomical subunits. Reconstructive challenges can lead to multiple revisional surgeries to achieve the final aesthetic result. This study aimed to evaluate risk factors and predictors of revisional surgery in patients undergoing reconstruction after Mohs micrographic surgery for nasal tumours. Methods: This was a prospective cohort study from April 2, 2008 to February 26, 2019. The study population included all consecutive patients who underwent Mohs micrographic surgery for nasal skin cancer. Resection and reconstruction of nasal skin cancer was performed by the Mohs team. Results: A total of 988 cases met our study inclusion criteria with 64 (6.5%) cases requiring unplanned surgical revision. Revision rates were highest in the ala (9.0%, p < 0.05) and complex anatomical subunits (16.7%, p < 0.0001). In contrast, revision rates for dorsum lesions were lowest (1.8%, p < 0.001). In terms of reconstructive modalities, local flaps resulted in significantly higher rates of revision when compared to grafts (relative risk, 2.37; 95% CI, 1.15–5.0; p < 0.01). In terms of histological diagnosis, squamous cell carcinoma had significantly higher revision rates when compared to basal cell carcinoma (p < 0.05). Conclusions: To our knowledge, this is the first study to report the risk factors and predictors of revision surgery in patients undergoing MMS for nasal tumours. This study highlights that the reconstructive modality utilised affects the functional and cosmetic outcome of MMS. We note that ala complex subunit lesions, squamous cell carcinoma and flap reconstruction were associated with an increased risk of revision after Mohs reconstruction of nasal lesions. Level of evidence: Level III, risk/prognostic; therapeutic study. Trial registration number: (Ref: PLA-19-20_A03) 04/02/2020
Accuracy of SIAscopy for pigmented skin lesions encountered in primary care: development and validation of a new diagnostic algorithm.
BACKGROUND: Diagnosing pigmented skin lesions in general practice is challenging. SIAscopy has been shown to increase diagnostic accuracy for melanoma in referred populations. We aimed to develop and validate a scoring system for SIAscopic diagnosis of pigmented lesions in primary care. METHODS: This study was conducted in two consecutive settings in the UK and Australia, and occurred in three stages: 1) Development of the primary care scoring algorithm (PCSA) on a sub-set of lesions from the UK sample; 2) Validation of the PCSA on a different sub-set of lesions from the same UK sample; 3) Validation of the PCSA on a new set of lesions from an Australian primary care population. Patients presenting with a pigmented lesion were recruited from 6 general practices in the UK and 2 primary care skin cancer clinics in Australia. The following data were obtained for each lesion: clinical history; SIAscan; digital photograph; and digital dermoscopy. SIAscans were interpreted by an expert and validated against histopathology where possible, or expert clinical review of all available data for each lesion. RESULTS: A total of 858 patients with 1,211 lesions were recruited. Most lesions were benign naevi (64.8%) or seborrhoeic keratoses (22.1%); 1.2% were melanoma. The original SIAscopic diagnostic algorithm did not perform well because of the higher prevalence of seborrhoeic keratoses and haemangiomas seen in primary care. A primary care scoring algorithm (PCSA) was developed to account for this. In the UK sample the PCSA had the following characteristics for the diagnosis of 'suspicious': sensitivity 0.50 (0.18-0.81); specificity 0.84 (0.78-0.88); PPV 0.09 (0.03-0.22); NPV 0.98 (0.95-0.99). In the Australian sample the PCSA had the following characteristics for the diagnosis of 'suspicious': sensitivity 0.44 (0.32-0.58); specificity 0.95 (0.93-0.97); PPV 0.52 (0.38-0.66); NPV 0.95 (0.92-0.96). In an analysis of lesions for which histological diagnosis was available (n = 111), the PCSA had a significantly greater Area Under the Curve than the 7-point checklist for the diagnosis of melanoma (0.83; 95% CI 0.71-0.95 versus 0.61; 95% CI 0.44-0.78; p = 0.02 for difference). CONCLUSIONS: The PCSA could have a useful role in improving primary care management of pigmented skin lesions. Further work is needed to develop and validate the PCSA in other primary care populations and to evaluate the cost-effectiveness of GP management of pigmented lesions using SIAscopy.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
Survival outcomes and interval between lymphoscintigraphy and SLNB in cutaneous melanoma- findings of a large prospective cohort study
Introduction: Sentinel lymph node biopsy (SLNB) in cutaneous melanoma (CM) is performed to identify patient at risk of regional and distant relapse. We hypothesized that timing of lymphoscintigraphy may influence the accuracy of SLNB and patient outcomes. Methods: We reviewed prospective data on patients undergoing SLNB for CM at a large university cancer-center between 2008-2015, examining patient and tumor demographics and time between lymphoscintigraphy (LS) and SLNB. Kaplan-Meier survival analysis assessed disease-specific (DSS) and overall-survival (OS), stratified by timing of LS. Cox multivariate regression analysis assessed independent risk factors for survival. Results: We identified 1015 patients. Median follow-up was 45 months (IQR 26-68 months). Univariate analysis showed a 6.8% absolute DSS (HR 1.6 [1.03-2.48], p= 0.04) benefit and a 10.7% absolute OS (HR 1.64 [1.13-2.38], p=0.01) benefit for patients whose SLNB was performed 12 hours (n=652). Multivariate analysis identified timing of LS as an independent predictor of OS (p=0.007) and DSS (p=0.016) when competing with age, sex, Breslow thickness (BT) and SLN status. No difference in nodal relapse rates (5.2% v 4.6%; p=0.67) was seen. Both groups were matched for age, sex, BT and SLN status. Conclusion: These data have significant implications for SLNB services, suggesting delaying SLNB >12 hours after LS using a Tc99-labelled nanocolloid has a significant negative survival impact for patients and should be avoided. We hypothesise that temporal tracer migration is the underlying cause and advocate further trials investigating alternative, 'stable' tracer-agents
The Neutrophil-Lymphocyte Ratio and Locoregional Melanoma: A Multicentre Cohort Study
Objectives The neutrophil–lymphocyte ratio (NLR) is an inflammatory biomarker which is useful in cancer prognostication.
We aimed to investigate the differences in baseline NLR between patients with localised and metastatic cutaneous melanoma and how this biomarker changed over time with the recurrence of disease.
Methods This multicentre cohort study describes patients treated for Stage I–III cutaneous melanoma over 10 years. The baseline NLR was measured immediately prior to surgery and again at the time of discharge or disease recurrence. The odds ratios (OR) for sentinel node involvement are estimated using mixed-effects logistic regression. The risk of recurrence is estimated using multivariable Cox regression.
Results Overall 1489 individuals were included. The mean baseline NLR was higher in patients with palpable nodal disease compared to those with microscopic nodal or localised disease (2.8 versus 2.4 and 2.3, respectively; p < 0.001). A baseline NLR ≥ 2.3 was associated with 30% higher odds of microscopic metastatic melanoma in the sentinel lymph node [adjusted OR 1.3 (95% CI 1.3, 1.3)]. Following surgery, 253 patients (18.7%) developed recurrent melanoma during surveillance although there was no statistically significant association between the baseline NLR and the risk of recurrence [adjusted HR 0.9 (0.7, 1.1)].
Conclusion The NLR is associated with the volume of melanoma at presentation and may predict occult sentinel lymph metastases. Further prospective work is required to investigate how NLR may be modelled against other clinicopathological variables to predict outcomes and to understand the temporal changes in NLR following surgery for melanoma
Place vs. Node transit: Planning policies revisited
A core contemporary planning approach is the promotion of transit-oriented developments (TODs) and in recent times cities have committed substantial financial investment to encourage sustainable precincts around public transport. Evaluation of the success of TODs is key for continuing the planning efforts. A frequently applied framework for characterizing TODs draws on Bertolini's Node-Place (N-P) model, enriched through application in various contexts. We offer here an extension to the N-P model, using a case study in a low-density city, Perth,Western Australia. A typology of railway stations is developed using 43 indicators and then linear models are applied to ascertain the association between patronage and station precinct features. The results show that various types of measures are required to increase public transport ridership for the four clusters that emerged from the analysis. Density alone does not lead to increased use of public transport; it must be associated with city-wide accessibility, as well as access/egress to and from the station
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