7,809 research outputs found
The impact of operative approach on outcome of surgery for gastro-oesophageal tumours
<p>Abstract</p> <p>Background</p> <p>The choice of operation for tumours at or around the gastro-oesophageal junction remains controversial with little evidence to support one technique over another. This study examines the prevalence of margin involvement and nodal disease and their impact on outcome following three surgical approaches (Ivor Lewis, transhiatal and left thoraco-laparotomy) for these tumours.</p> <p>Methods</p> <p>A retrospective analysis was conducted of patients undergoing surgery for distal oesophageal and gastro-oesophageal junction tumours by a single surgeon over ten years. Comparisons were undertaken in terms of tumour clearance, nodal yield, postoperative morbidity, mortality, and median survival. All patients were followed up until death or the end of the data collection (mean follow up 33.2 months).</p> <p>Results</p> <p>A total of 104 patients were operated on of which 102 underwent resection (98%). Median age was 64.1 yrs (range 32.1–79.4) with 77 males and 25 females. Procedures included 29 Ivor Lewis, 31 transhiatal and 42 left-thoraco-laparotomies. Postoperative mortality was 2.9% and median survival 23 months. Margin involvement was 24.1% (two distal, one proximal and 17 circumferential margins). Operative approach had no significant effect on nodal clearance, margin involvement, postoperative mortality or morbidity and survival. Lymph node positive disease had a significantly worse median survival of 15.8 months compared to 39.7 months for node negative (<it>p </it>= 0.007), irrespective of approach.</p> <p>Conclusion</p> <p>Surgical approach had no effect on postoperative mortality, circumferential tumour, nodal clearance or survival. This suggests that the choice of operative approach for tumours at the gastro-oesophageal junction may be based on the individual patient and tumour location rather than surgical dogma.</p
Competitive Data Trading Model with Privacy Valuation for Multiple Stakeholders in IoT Data Markets
With the widespread of Internet of Things (IoT) environment, a big data concept has emerged to handle a large number of data generated by IoT devices. Moreover, since data- driven approaches now become important for business, IoT data markets have emerged, and IoT big data are exploited by major stakeholders such as data brokers and data service providers. Since many services and applications utilize data analytic methods with collected data from IoT devices, the conflict issues between privacy and data exploitation are raised, and the markets are mainly categorized as privacy protection markets and privacy valuation markets, respectively. Since these kinds of data value chains (which are mainly considered by business stakeholders) are revealed, data providers are interested in proper incentives in exchange for their privacy (i.e., privacy valuation) under their agreement. Therefore, this paper proposes a competitive data trading model that consists of data providers who weigh the value between privacy protection and valuation as well as other business stakeholders. Each data broker considers the willingness-to-sell of data providers, and a single data service provider considers the willingness-to-pay of service consumers. At the same time, multiple data brokers compete to sell their dataset to the data service provider as a non-cooperative game model. Based on the Nash Equilibrium analysis (NE) of the game, the feasibility is shown that the proposed model has the unique NE that maximizes the profits of business stakeholders while satisfying all market participants
A lifecourse mendelian randomization study highlights the long-term influence of childhood body size on later life heart structure
Children with obesity typically have larger left ventricular heart dimensions during adulthood. However, whether this is due to a persistent effect of adiposity extending into adulthood is challenging to disentangle due to confounding factors throughout the lifecourse. We conducted a multivariable mendelian randomization (MR) study to separate the independent effects of childhood and adult body size on 4 magnetic resonance imaging (MRI) measures of heart structure and function in the UK Biobank (UKB) study. Strong evidence of a genetically predicted effect of childhood body size on all measures of adulthood heart structure was identified, which remained robust upon accounting for adult body size using a multivariable MR framework (e.g., left ventricular end-diastolic volume (LVEDV), Beta = 0.33, 95% confidence interval (CI) = 0.23 to 0.43, P = 4.6 × 10-10). Sensitivity analyses did not suggest that other lifecourse measures of body composition were responsible for these effects. Conversely, evidence of a genetically predicted effect of childhood body size on various other MRI-based measures, such as fat percentage in the liver (Beta = 0.14, 95% CI = 0.05 to 0.23, P = 0.002) and pancreas (Beta = 0.21, 95% CI = 0.10 to 0.33, P = 3.9 × 10-4), attenuated upon accounting for adult body size. Our findings suggest that childhood body size has a long-term (and potentially immutable) influence on heart structure in later life. In contrast, effects of childhood body size on other measures of adulthood organ size and fat percentage evaluated in this study are likely explained by the long-term consequence of remaining overweight throughout the lifecourse
Graphene oxide incorporated polysulfone substrate for the fabrication of flat-sheet thin-film composite forward osmosis membranes
© 2015 Elsevier B.V. The preparation and performances of the newly synthesized thin film composite (TFC) forward osmosis (FO) membranes with graphene oxide (GO)-modified support layer are presented in this study. GO nanosheets were incorporated in the polysulfone (PSf) to obtain PSf/GO composite membrane support layer. Polyamide (PA) active layer was subsequently formed on the PSf/GO by interfacial polymerization to obtain the TFC-FO membranes. Results reveal that at an optimal amount of GO addition (0.25wt%), a PSf/GO composite support layer with favorable structural property measured in terms of thickness, porosity and pore size can be achieved. The optimum incorporation of GO in the PSF support layer not only significantly improved water permeability but also allowed effective PA layer formation, in comparison to that of pure PSf support layer which had much lower water permeability. Thus, a TFC-FO membrane with high water flux (19.77Lm-2h-1 against 6.08Lm-2h-1 for pure PSf) and reverse flux selectivity (5.75Lg-1 against 3.36Lg-1 for pure PSf) was obtained under the active layer facing the feed solution or AL-FS membrane orientation. Besides the improved structural properties (reduced structural parameter, S) of the support layer, enhanced support hydrophilicity also contributed to the improved water permeability of the membrane. Beyond a certain point of GO addition (≥0.5wt%), the poor dispersion of GO in dope solution and significant structure change resulted in lower water permeation and weaker mechanical properties in support as well as FO flux/selectivity of consequent TFC membrane. Overall, this study suggests that GO modification of membrane supports could be a promising technique to improve the performances of TFC-FO membranes
Chemically Cross-Linked Graphene Oxide as a Selective Layer on Electrospun Polyvinyl Alcohol Nanofiber Membrane for Nanofiltration Application.
Graphene oxide (GO) nanosheets were utilized as a selective layer on a highly porous polyvinyl alcohol (PVA) nanofiber support via a pressure-assisted self-assembly technique to synthesize composite nanofiltration membranes. The GO layer was rendered stable by cross-linking the nanosheets (GO-to-GO) and by linking them onto the support surface (GO-to-PVA) using glutaraldehyde (GA). The amounts of GO and GA deposited on the PVA substrate were varied to determine the optimum nanofiltration membrane both in terms of water flux and salt rejection performances. The successful GA cross-linking of GO interlayers and GO-PVA via acetalization was confirmed by FTIR and XPS analyses, which corroborated with other characterization results from contact angle and zeta potential measurements. Morphologies of the most effective membrane (CGOPVA-50) featured a defect-free GA cross-linked GO layer with a thickness of ~67 nm. The best solute rejections of the CGOPVA-50 membrane were 91.01% for Na2SO4 (20 mM), 98.12% for Eosin Y (10 mg/L), 76.92% for Methylene blue (10 mg/L), and 49.62% for NaCl (20 mM). These findings may provide one of the promising approaches in synthesizing mechanically stable GO-based thin-film composite membranes that are effective for solute separation via nanofiltration
A review of fMRI simulation studies
Simulation studies that validate statistical techniques for fMRI data are challenging due to the complexity of the data. Therefore, it is not surprising that no common data generating process is available (i.e. several models can be found to model BOLD activation and noise). Based on a literature search, a database of simulation studies was compiled. The information in this database was analysed and critically evaluated focusing on the parameters in the simulation design, the adopted model to generate fMRI data, and on how the simulation studies are reported. Our literature analysis demonstrates that many fMRI simulation studies do not report a thorough experimental design and almost consistently ignore crucial knowledge on how fMRI data are acquired. Advice is provided on how the quality of fMRI simulation studies can be improved
Personal Data Trading Scheme for Data Brokers in IoT Data Marketplaces
With the widespread use of IoT, data-driven services take the lead of both online and offline businesses. Especially, personal data draw heavy attention to service providers because of usefulness in value-added services. With the emerging big-data technology, a data broker appears, which exploits and sells personal data about individuals to other third parties. Due to little transparency between providers and brokers/consumers, people think the current ecosystem is not trustworthy; and new regulations with strengthening the rights of individuals were introduced. Therefore, people have an interest in their privacy valuation. In this sense, the willingness-to-sell (WTS) of providers becomes one of the important aspects for data brokers; however, conventional studies have mainly focused on the willingness-to-buy (WTB) of consumers. Therefore, this paper proposes an optimized trading model for data brokers which buy personal data with proper incentives based on the WTS, and they sell valuable information from the refined dataset by considering the WTB and the dataset quality. This paper shows that the proposed model has the global optimal point by the convex optimization technique and proposes a gradient ascent based algorithm. Consequently, it shows that the proposed model is feasible even if data brokers spend costs to gather personal data
External sources of clean technology: evidence from the clean development mechanism
New technology is fundamental to sustainable development. However, inventors from industrialized countries often refuse technology transfer because they worry about reverse-engineering. When can clean technology transfer succeed? We develop a formal model of the political economy of North–South technology transfer. According to the model, technology transfer is possible if (1) the technology in focus has limited global commercial potential or (2) the host developing country does not have the capacity to absorb new technologies for commercial use. If both conditions fail, inventors from industrialized countries worry about the adverse competitiveness effects of reverse-engineering, so technology transfer fails. Data analysis of technology transfer in 4,894 projects implemented under the Kyoto Protocol’s Clean Development Mechanism during the 2004–2010 period provides evidence in support of the model
Reduced haemodynamic response in the ageing visual cortex measured by absolute fNIRS
The effect of healthy ageing on visual cortical activation is still to be fully explored. This study aimed to elucidate whether the haemodynamic response (HDR) of the visual cortex altered as a result of ageing. Visually normal (healthy) participants were presented with a simple visual stimulus (reversing checkerboard). Full optometric screening was implemented to identify two age groups: younger adults (n = 12, mean age 21) and older adults (n = 13, mean age 71). Frequency-domain Multi-distance (FD-MD) functional Near-Infrared Spectroscopy (fNIRS) was used to measure absolute changes in oxygenated [HbO] and deoxygenated [HbR] haemoglobin concentrations in the occipital cortices. Utilising a slow event-related design, subjects viewed a full field reversing checkerboard with contrast and check size manipulations (15 and 30 minutes of arc, 50% and 100% contrast). Both groups showed the characteristic response of increased [HbO] and decreased [HbR] during stimulus presentation. However, older adults produced a more varied HDR and often had comparable levels of [HbO] and [HbR] during both stimulus presentation and baseline resting state. Younger adults had significantly greater concentrations of both [HbO] and [HbR] in every investigation regardless of the type of stimulus displayed (p<0.05). The average variance associated with this age-related effect for [HbO] was 88% and [HbR] 91%. Passive viewing of a visual stimulus, without any cognitive input, showed a marked age-related decline in the cortical HDR. Moreover, regardless of stimulus parameters such as check size, the HDR was characterised by age. In concurrence with present neuroimaging literature, we conclude that the visual HDR decreases as healthy ageing proceeds
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