Diagnostic value of distal colonic polyps for prediction of advanced proximal neoplasia in an average-risk population undergoing screening colonoscopy

For colorectal cancer screening, the predictive value of distal findings in the ascertainment of proximal lesions is not fully established. The aims of this study were to assess distal findings as predictors of advanced proximal neoplasia and to compare the predictive value of endoscopy alone vs. combined endoscopic and histopathologic data. METHODS: Primary colonoscopy screening was performed in 2210 consecutive, average-risk adults. Age, gender, endoscopic (size, number of polyps), and histopathologic distal findings were used as potential predictors of advanced proximal neoplasms (i.e., any adenoma > or =1 cm in size, and/or with villous histology, and/or with severe dysplasia or invasive cancer). Polyps were defined as distal if located in the descending colon, the sigmoid colon, or the rectum. Those in other locations were designated proximal. RESULTS: Neoplastic lesions, including 11 invasive cancers, were found in 617 (27.9%) patients. Advanced proximal neoplasms without any distal adenoma were present in 1.3% of patients. Of the advanced proximal lesions, 39% were not associated with any distal polyp. Older age, male gender, and distal adenoma were independent predictors of advanced proximal neoplasms. The predictive ability of a model with endoscopic data alone did not improve after inclusion of histopathologic data. In multivariate logistic regression analysis, the predictive ability of models that use age, gender, and any combination of distal findings was relatively low. The proportion of advanced proximal neoplasms identified if any distal polyp was an indication for colonoscopy was only 62%. CONCLUSIONS: A strategy in which colonoscopy is performed solely in patients with distal colonic findings is not effective screening for the detection of advanced proximal neoplasms in an average-risk populatio

Use of colonoscopy as a primary screening test for colorectal cancer in average risk people

The use of colonoscopy as a primary screening test for colorectal cancer (CRC) in average risk adults is a subject of controversy. Our primary objective was to build a predictive model based on a few simple variables that could be used as a guide for identifying average risk adults more suitable for examination with colonoscopy as a primary screening test. METHODS: The prevalence of advanced adenomas was assessed by primary screening colonoscopy in 2210 consecutive adults at least 40 yr old, without known risk factors for CRC. Age, gender, and clinical and biochemical data were compared among people without adenomas, those with non-advanced adenomas, and those with any advanced neoplasm. A combined score to assess the risk of advanced adenomas was built with the variables selected by multiple logistic regression analysis. RESULTS: Neoplastic lesions were found in 617 subjects (27.9%), including 259 with at least one neoplasm that was 10 mm or larger, villous, or with moderate-to-severe dysplasia, and 11 with invasive cancers. Advanced lesions were more frequent among men, older people, and those with a higher body mass index (BMI). These three variables were independent predictors of advanced adenomas in multivariate analysis. A score combining age, sex, and BMI was developed as a guide for identifying individuals more suitable for screening colonoscopy. CONCLUSIONS: Age, gender, and BMI can be used to build a simple score to select those average risk adults who might be candidates for primary screening colonoscop

Solar-assisted heat pump coupled to solar hybrid panels

A water-water solar-assisted heat pump (SAHP) is going to be installed on an academic building at the University of Zaragoza (Spain). It integrates a heat pump heating system with photovoltaics/thermal collectors and seasonal storage. Considerably higher performances than a conventional type air-source heat pump are expected to be reached. This paper shows the simulation of the system performed in trnsys, a graphically based software used to simulate the behaviour of transient systems. The obtained energy and monetary savings are analysed

Analysis and optimization of a heat pump system coupled to an installation of PVT panels and a seasonal storage tank on an educational building

A water-water solar-assisted heat pump (SAHP) is projected on an under construction academic building at the University of Zaragoza (Spain). It integrates a heat pump heating system with photovoltaic/thermal collectors and seasonal storage. Because of its innovative design, considerably higher performances than a conventional type air-source heat pump are expected. This paper shows the simulation of the system performed in TRNSYS, a graphically based software used to simulate the behavior of transient systems. In addition, starting from the current design of the energy system, different sensibility analysis are simulated in order to study alternative configurations of the heating system. The solar coverage of the current installation design is about 60% and the expected savings yield to a payback period of 15, 4 years. Three alternative configurations are proposed in this work, reaching up to around 98% of solar coverage. The study results show the technical and economic feasibility of the heating installation based on a solar assisted heat pump with implementation of seasonal storage in an educational building located in a middle latitude

Exergy assessment and exergy cost analysis of a renewable-based and hybrid trigeneration scheme for domestic water and energy supply

Exergy and exergy cost analyses are proposed as complementary methods for the assessment and better understanding of the efficiency of a hybrid trigeneration system based on renewable energy sources. The system combines photovoltaic/thermal collectors, an evacuated tube collector and a wind turbine and produces electricity, sanitary hot water and desalted fresh water for a single family house. The system includes two desalination technologies (reverse osmosis and membrane distillation) that consume power and heat respectively, and two kinds of energy storage devices (a hot water tank and two lead-acid batteries). The assessment is based on simulations developed by using TRNSYS software. As a first level of detail, exergy analysis is applied in ten-minute basis to selected plant components. As a second level of detail, it is proposed to apply exergy-based indicators that summarize the system behavior during a longer period of time (monthly basis). By using aggregated values, exergy accumulation terms become negligible, what allows applying symbolic thermoeconomics to calculate exergy cost and to analyze in depth the process of cost formation. The system has an exergy efficiency of 7.76% (6.68 due to electricity, 0.33 due to fresh water and 0.75 due to sanitary hot water)

Analysis of a domestic trigeneration scheme with hybrid renewable energy sources and desalting techniques

In this paper, experimental tests of a hybrid trigeneration pilot unit based on renewable energy sources are presented and analyzed. The plant provides electricity by coupling four photovoltaic/thermal collectors and a micro-wind turbine, fresh water by means of hybrid desalination (membrane distillation, and reverse osmosis), and sanitary hot water coming from the photovoltaic/thermal collectors and an evacuated tubes collector. Plant design was previously modeled to cover the power, freshwater and sanitary hot water for a typical family home (four residents) isolated from the power and water networks. The hybrid pilot unit has been tested from May 2017 to March 2018 in Zaragoza (Spain). Results from those tests show that daytime assessment of power, freshwater and sanitary hot water produced allowed a good coverage of scheduled energy and water demands. Flexible operation due to the combined production of power and heat was also observed. State of charge of the batteries and the temperature of the sanitary hot water tank are the key control variables, which allow to give priority to power, freshwater or sanitary hot water production according to the ordered demands or economic incentives. Environmental assessment of the pilot unit along its life cycle also has shown very low impacts with respect to the conventional supply of energy and water

Energy arbitrage in PV-PHS systems

In this paper, we use MHOGA software for the evaluation of adding pumped hydro storage (PHS) for energy arbitrage in utility-scale PV generating systems. PHS is used for electricity price arbitrage, pumping water from the lower reservoir to the upper reservoir with the PV generation during hours of low electricity price and generating electricity by means of the stored water with the turbine during hours of high price (during these hours the PV generator also injects its production to the grid). The control strategy creates setpoints for the use of the pump and the turbine, trying to obtain the maximum benefits from the electricity sold to the grid, maximizing the net present value (NPV). An example of application is shown, obtaining conclusions about the economical viability of the PV-PHS system compared to the PV-only system: in the case studied in this work, it is not worth to add PHS to the PV system

Stable hydrogen generation by wind power, grid and battery

In this work, we study the stable generation of hydrogen by means of the electrolyzer fed by renewable sources, battery and grid. Due to the intermittent nature of the renewable sources (PV, wind), the hydrogen generation by the electrolyzer cannot be stable during the time except if there is another electricity source to fulfil the difference between the electrolyzer nominal power and the renewable power. The AC electrical grid will supply that difference during hours when the electricity price is low, while the batteries will supply the difference when the electricity price is high. Also, batteries will be charged by the grid when electricity price is low. We compare the performance and economical results with the case of using only the grid for supplying that difference. Considering a hypothetical electricity hourly price with 3% annual inflation, the system with battery has a levelized cost of hydrogen (LCOH) of 4.25 €/kg with the actual present battery CAPEX (200 €/kWh) while it has a LCOH of 3.95 €/kg if we consider a much lower future battery CAPEX of 20 €/kWh (10 times lower than nowadays). The system without battery has a LCOH of 4.14 €/kg

Short term energy management in stand-alone PV-battery-diesel systems

In this work, the short term (daily) operation of an off-grid hybrid PV-diesel-battery system is optimized by genetic algorithms. An integer variable (0, 1 or 2) for each hour of the day decides the way the battery works. With the forecast of the hourly irradiation, temperature and load consumption for the next day, and estimating the state of charge of the battery (SOC) at the first hour of the day, we perform the optimization of the integer variables for the 24 hours of next day. To avoid inadmissible computation time, the optimization is performed by using genetic algorithms (GA) obtaining in roughly 1 hour the optimal solution or a solution near the optimal one. The optimization tries to obtain the minimal total cost of the daily operation while supplying the whole load. We compare the results of the optimization with the typical control strategies (load following, cycle charging and set point strategies), obtaining better results with the new optimized strategy. The reduction in the operational cost obtained varies from 2.5% to 62%, compared to the typical control strategies (load following or cycle charging)

A REVIEW OF RECORDING TECHNOLOGIES FOR DIGITAL FABRICATION IN HERITAGE CONSERVATION

Digital tools have brought new techniques for recording and fabrication allowing for the augmentation of traditional processes in repairs and restorations. Traditional mechanical and chemical techniques require physical contact to the artefacts of interest, while LiDAR Scanning, photogrammetry and structured light scanning provide non-invasive solutions. Analog recording technologies have always informed fabrication processes, but contemporary digital recording can produce complete geometry for fabrication. In this paper, we discuss recording and fabrication technologies and how they have been applied for heritage conservation