32 research outputs found
Uncertainty and sensitivity in global carbon cycle modelling.
Get PDFThis paper summarises the results obtained from a stochastic sensitivity study in the area of global carbon cycle modelling. In particular, it outlines how Monte Carlo Simulation (MCS) techniques and associated Generalised Sensitivity Analysis (GSA) have been applied to a modified box-diffusion model. Using parametric and input uncertainty measures derived from independent sources, the analysis shows that the model produces an ensemble response for atmospheric CO2 whose mean evolution is reasonably consistent with that observed over the industrial period (1765 to 1990). However, the situation is more ambiguous in relation to the amplitude distribution of the stochastic realisations: here, there is a larger than expected variance arising from the assumed uncertainty, although this may be due to unavoidable limitations in the assumptions about parameteric uncertainty used in the MCS analysis. The analysis also shows that the a priori model response is less consistent with 13C measurements and not at all consistent with the 14C observations, while GSA suggests that, from over 20 model parameters, only a small number have a statistically significant effect on the model response in 1990. In addition, the results from MCS, using the IPCC (Intergovernmental Panel on Climate Change) Scenario IS92a inputs, demonstrate that the uncertainties in the projections of the CO2 concentrations using this model are significantly higher than those suggested so far using deterministic methods. Finally, the advantages and disadvantages of the stochastic methodology are discussed
3D Scene Compression for Autonomous Driving using Neural Radiance Fields
No full textNeural Radiance Fields (NeRFs) have showcased remarkable effectiveness in capturing complex 3D scenes and synthesizing novel viewpoints. By inherently capturing the entire scene in a compact representation, they offer a promising avenue for applications such as simulators, where efficient storage of real-world data, fast rendering and dynamic generation of new content are crucial. However, the potential for compression in NeRFs has been largely neglected in the existing literature. Moreover, the practical deployment of NeRFs in real-world scenarios, including simulators, faces significant obstacles such as constraints in training time, rendering speed, and scalability to large scenes. While recent advancements have tackled some of these hurdles individually, none have offered a comprehensive solution. In this paper, we introduce a new NeRF architecture based on a textured polygon-based method and augment this architecture by integrating encodings to expedite training. Additionally, we introduce learned pose refinement and an appearance embedding to enhance scalability to larger scenes. Through experimentation on the nuScenes dataset, we demonstrate that our method achieves competitive reconstruction performance with existing techniques while surpassing them in rendering speed. Furthermore, in terms of compression, our findings indicate that our method achieves competitive compression rates comparable to image-based compression techniques, while also enabling novel-view synthesis. This underscores its potential utility in applications like simulators.Mechanical Engineering | Vehicle Engineering | Cognitive Robotic
Systemic anticancer therapy for urothelial carcinoma: UK oncologists’ perspective
Get PDFUrothelial carcinoma (UC) is a common cancer associated with a poor prognosis in patients with advanced disease. Platinum-based chemotherapy has remained the cornerstone of systemic anticancer treatment for many years, and recent developments in the treatment landscape have improved outcomes. In this review, we provide an overview of systemic treatment for UC, including clinical data supporting the current standard of care at each point in the treatment pathway and author interpretations from a UK perspective. Neoadjuvant cisplatin-based chemotherapy is recommended for eligible patients with muscle-invasive bladder cancer and is preferable to adjuvant treatment. For first-line treatment of advanced UC, platinum-eligible patients should receive cisplatin- or carboplatin-based chemotherapy, followed by avelumab maintenance in those without disease progression. Among patients unable to receive platinum-based chemotherapy, immune checkpoint inhibitor (ICI) treatment is an option for those with programmed death ligand 1 (PD-L1)–positive tumours. Second-line or later treatment options depend on prior treatment, and enfortumab vedotin is preferred after prior ICI and chemotherapy, although availability varies between countries. Additional options include rechallenge with platinum-based chemotherapy, an ICI, or non–platinum-based chemotherapy. Areas of uncertainty include the optimal number of first-line chemotherapy cycles for advanced UC and the value of PD-L1 testing for UC
The Design of a ’Water Droplet’-Based UFP Mitigation System at Airports: A Case Study at Amsterdam Airport Schiphol
No full textThis research explored potential designs of an innovative mitigation strategy to combat the aircraft-produced ultrafine particle (UFP) concentrations at Amsterdam Airport Schiphol (AMS). This technique is based on the principle that fine water droplets are able to encapsulate dust and fine particles, which clump together and eventually descent to the ground. The reduction of airborne particle concentrations is expected to have a significant effect on the health of (platform) employees, which makes it an interesting strategy to further investigate. A wide variety of stakeholders, from both the aviation industry and the academic world, were interviewed about the important design components that need to be incorporated in a potential mitigation system, as well as essential requirements that the system needs to comply with. A system that integrated the cold start of the aircraft engines as the most suitable moment and the introduction of remote starting positions as the most optimal location for the implementation of UFP mitigation strategies, contributed to the proposed conceptual design for AMS. A system alternative in which the water droplets are directed into the jet engine outlets by spraying cannons was discussed for a close-up mitigation strategy, while an alternative in which a screen of water droplets is created to absorb the jet blast with emissions was established for the mitigation strategy at a further distance. The assessment of the conceptual system design, on its feasibility, viability and desirability, showed that the UFP mitigation system could have a desirable impact on Schiphol’s environment on the short-term. However, the possibilities of implementing remote starting positions at AMS and the impact that the system has on the starting capacity and the turnaround time should be further investigated to increase the system’s feasibility and viability.Transport, Infrastructure and Logistic
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A data assimilation method for using low-resolution Earth observation data in heterogeneous ecosystems
Get PDFThe Natural Environment Research Council (NERC) funded this work through the National Centre for Earth Observation (NCEO) and the Centre for Terrestrial Carbon Dynamics (CTCD).We present an approach for dealing with coarse-resolution Earth observations (EO) in terrestrial ecosystem data assimilation schemes. The use of coarse-scale observations in ecological data assimilation schemes is complicated by spatial heterogeneity and nonlinear processes in natural ecosystems. If these complications are not appropriately dealt with, then the data assimilation will produce biased results. The "disaggregation" approach that we describe in this paper combines frequent coarse-resolution observations with temporally sparse fine-resolution measurements. We demonstrate the approach using a demonstration data set based on measurements of an Arctic ecosystem. In this example, normalized difference vegetation index observations are assimilated into a "zero-order" model of leaf area index and carbon uptake. The disaggregation approach conserves key ecosystem characteristics regardless of the observation resolution and estimates the carbon uptake to within 1% of the demonstration data set "truth." Assimilating the same data in the normal manner, but without the disaggregation approach, results in carbon uptake being underestimated by 58% at an observation resolution of 250 m. The disaggregation method allows the combination of multiresolution EO and improves in spatial resolution if observations are located on a grid that shifts from one observation time to the next. Additionally, the approach is not tied to a particular data assimilation scheme, model, or EO product and can cope with complex observation distributions, as it makes no implicit assumptions of normality.Peer reviewe
Acquiring a Pet Dog Significantly Reduces Stress of Primary Carers for Children with Autism Spectrum Disorder: A Prospective Case Control Study
No full textThe Author(s) 2015. This article is published with open access at Springerlink.com Abstract This study describes the impact of pet dogs on stress of primary carers of children with Autism Spectrum Disorder (ASD). Stress levels of 38 primary carers ac-quiring a dog and 24 controls not acquiring a dog were sampled at: Pre-intervention (17 weeks before acquiring a dog), post-intervention (3–10 weeks after acquisition) and follow-up (25–40 weeks after acquisition), using the Par-enting Stress Index. Analysis revealed significant im-provements in the intervention compared to the control group for Total Stress, Parental Distress and Difficult Child. A significant number of parents in the intervention group moved from clinically high to normal levels of Parental Distress. The results highlight the potential of pet dogs to reduce stress in primary carers of children with an ASD
Integrated Disciplines: Understanding the Role of Art in Science Education in a Preschool
No full textAbs tract: The Reggio Emilia approach has brought a special vis ion about pres chool curricula. The current s t udy focus es specifically on art and science education within the framework of Reggio Emilian emerg e n t curriculu m. W h at makes this special vis ion of art unique is "creativity" as well as "dis covery" embedded in it and the innovative, varied ways art lets pres choolers repres ent their ideas related to the natural world. The current study, which is bas ed on author's in s ights gained in a Reggio Emilia-ins pired pres chool at a Midwes tern res earch univers ity in the United States of America, provides some sugges tion s and examples to help teachers make art and natural sciences work together in h a rmony in their Reggio Emiliains pired projects . It shows what kinds of scientific skills , tools and te c h n iq u e s o n e pres chool utilizes to help its pres choolers purs ue their s cientific inquiries and work on science projects in which arts embedded. Five element s , w h ic h a re derived from the author's in-clas s participatory obs ervations , dis play the ways te a c h e rs are able to help the pres choolers grow in their ability to practice s cientific inquiry doing science projects and repres enting their ideas through their art
TransCom model simulations of hourly atmospheric CO2: Analysis of synoptic-scale variations for the period 2002-2003
Get PDFThe ability to reliably estimate CO2 fluxes from current in situ atmospheric CO2 measurements and future satellite CO2 measurements is dependent on transport model performance at synoptic and shorter timescales. The TransCom continuous experiment was designed to evaluate the performance of forward transport model simulations at hourly, daily, and synoptic timescales, and we focus on the latter two in this paper. Twenty-five transport models or model variants submitted hourly time series of nine predetermined tracers (seven for CO2) at 280 locations. We extracted synoptic-scale variability from daily averaged CO2 time series using a digital filter and analyzed the results by comparing them to atmospheric measurements at 35 locations. The correlations between modeled and observed synoptic CO2 variabilities were almost always largest with zero time lag and statistically significant for most models and most locations. Generally, the model results using diurnally varying land fluxes were closer to the observations compared to those obtained using monthly mean or daily average fluxes, and winter was often better simulated than summer. Model results at higher spatial resolution compared better with observations, mostly because these models were able to sample closer to the measurement site location. The amplitude and correlation of model-data variability is strongly model and season dependent. Overall similarity in modeled synoptic CO2 variability suggests that the first-order transport mechanisms are fairly well parameterized in the models, and no clear distinction was found between the meteorological analyses in capturing the synoptic-scale dynamics
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