Thermal Comfort Assessment Based on Measurement and Questionnaire Surveys in a Large Mechanically Ventilated Space

This paper presents a thermal comfort study in a large occupied office (floor-to-ceiling height >5m) ventilated by a simple mixing ventilation system. The evaluation was conducted during the summer seasons of 2016 and 2017 using three different tools; (a) long term monitoring, (b) short term detailed measurements and (c) occupant questionnaire. Long term monitoring included air temperature and relative humidity at several locations and heights within the space with external conditions retrieved form a weather station on the roof of the building. The short term spot measurements included air temperature, relative humidity and air speed each at three vertical occupancy heights and the inlet diffusers. The surveys involved collection data using questionnaires developed based on ISO 10551. Analysis of long term data using temperature clouds indicate that the building can be approximated to be free running. A comparison between the measurement (analysed using PMV/PPD and adaptive thermal comfort) and the questionnaire surveys’ results show good agreement between predictions and occupant evaluation. The existing ventilation system was able to meet the requirement for thermal comfort in this large enclosure. However, with regards to the air movement, it did not achieve the recommended levels and this has affected occupant responses

Performance Characteristics of the 5-Ring GE Discovery Mi PET/CT Scanner Using AAPM Tg-126 Report

AIM: To report on the performance characteristics of the 5-ring GE Discovery MI PET/CT systems using the AAPM TG-126 report and compare these results to NEMA NU 2-2012 where applicable. MATERIALS AND METHODS: TG-126 testing was performed on two GE 5-Rings Discovery MI scanners. Tests performed included spatial resolution, PET/CT image-registration accuracy, sensitivity, count rate performance, accuracy of corrections, image contrast, scatter/attenuation correction, and image uniformity. All acquired data were analyzed using scanner console or free software tools as described by TG-126 and the results were then compared to published NEMA NU 2-2012 values. RESULTS: Both scanners gave similar resolution results for TG-126 and NEMA NU 2-2012 and were within manufacturer specifications. Image-registration accuracy between PET and CT using our clinical protocol showed excellent results with values ≤1 mm. Sensitivity using TG-126 was 19.43 cps/kBq while for NEMA the value was 20.73 cps/kBq. The peak noise-equivalent counting rate was 2174 kcps at 63.1 kBq/mL and is not comparable to NEMA NU 2-2012 due to differences in phantoms and methods used to measure and calculate this parameter. The accuracy of corrections for count losses for TG-126 were expressed in SUV values and found to be within 10% of the expected SUV measurement of 1. Image contrast and scatter/attenuation correction using the TG-126 method gave acceptable results. Image uniformity assessment resulted in values within the recommended ± 5% limits. CONCLUSION: These results show that the 5-ring GE Discovery MI PET/CT scanner testing using TG-126 is reproducible and has similar results to NEMA NU 2-2012 tests where applicable. We hope these results start to form the basis to compare PET/CT systems using TG-126

Simultaneous Hip Implant Segmentation and Gruen Landmarks Detection

The assessment of implant status and complications of Total Hip Replacement (THR) relies mainly on the clinical evaluation of the X-ray images to analyse the implant and the surrounding rigid structures. Current clinical practise depends on the manual identification of important landmarks to define the implant boundary and to analyse many features in arthroplasty X-ray images, which is time-consuming and could be prone to human error. Semantic segmentation based on the Convolutional Neural Network (CNN) has demonstrated successful results in many medical segmentation tasks. However, these networks cannot define explicit properties that lead to inaccurate segmentation, especially with the limited size of image datasets. Our work integrates clinical knowledge with CNN to segment the implant and detect important features simultaneously. This is instrumental in the diagnosis of complications of arthroplasty, particularly for loose implant and implant-closed bone fractures, where the location of the fracture in relation to the implant must be accurately determined. In this work, we define the points of interest using Gruen zones that represent the interface of the implant with the surrounding bone to build a Statistical Shape Model (SSM). We propose a multitask CNN that combines regression of pose and shape parameters constructed from the SSM and semantic segmentation of the implant. This integrated approach has improved the estimation of implant shape, from 74% to 80% dice score, making segmentation realistic and allowing automatic detection of Gruen zones. To train and evaluate our method, we generated a dataset of annotated hip arthroplasty X-ray images that will be made available

Genetic deficiency of indoleamine 2,3-dioxygenase promotes gut microbiota-mediated metabolic health.

The association between altered gut microbiota, intestinal permeability, inflammation and cardiometabolic diseases is becoming increasingly clear but remains poorly understood1,2. Indoleamine 2,3-dioxygenase is an enzyme induced in many types of immune cells, including macrophages in response to inflammatory stimuli, and catalyzes the degradation of tryptophan along the kynurenine pathway. Indoleamine 2,3-dioxygenase activity is better known for its suppression of effector T cell immunity and its activation of regulatory T cells3,4. However, high indoleamine 2,3-dioxygenase activity predicts worse cardiovascular outcome5-9 and may promote atherosclerosis and vascular inflammation6, suggesting a more complex role in chronic inflammatory settings. Indoleamine 2,3-dioxygenase activity is also increased in obesity10-13, yet its role in metabolic disease is still unexplored. Here, we show that obesity is associated with an increase of intestinal indoleamine 2,3-dioxygenase activity, which shifts tryptophan metabolism from indole derivative and interleukin-22 production toward kynurenine production. Indoleamine 2,3-dioxygenase deletion or inhibition improves insulin sensitivity, preserves the gut mucosal barrier, decreases endotoxemia and chronic inflammation, and regulates lipid metabolism in liver and adipose tissues. These beneficial effects are due to rewiring of tryptophan metabolism toward a microbiota-dependent production of interleukin-22 and are abrogated after treatment with a neutralizing anti-interleukin-22 antibody. In summary, we identify an unexpected function of indoleamine 2,3-dioxygenase in the fine tuning of intestinal tryptophan metabolism with major consequences on microbiota-dependent control of metabolic disease, which suggests indoleamine 2,3-dioxygenase as a potential therapeutic target

Impact of conjugated olefins on nickel-molybdenum-sulphide supported on gamma-alumina catalyst deactivation and fouling of naphtha hydrotreaters

This dissertation investigates the reactions of conjugated olefins that lead to catalyst deactivation and fouling in naphtha hydrotreater reactors using a commercial Ni-Mo-S/γ-Al₂O₃ catalyst. The reactions were performed in a micro-scale fixed bed reactor system operated at 150-250°C, 3-4 MPa H₂, LHSV of 1-8 hr-¹ and a H₂/feed ratio of 392-1200 standard mL/mL. During isoprene hydrogenation, an increase in dimerization activity with temperature was attributed to a higher activation energy of dimerization compared to hydrogenation. Conjugated olefin content was also shown to impact oligomerization as an increase in the conjugated olefin content resulted in a decrease in hydrogenation product yield while the oligomerization activity and gum content increased. By investigating different olefin structures, conjugation was shown to enhance dimerization/oligomerization while steric hindrance limited dimer/oligomer formation by limiting access and reactivity of the double bonds. The addition of cyclohexene to 4-methylstyrene resulted in a significant loss in catalyst hydrogenation activity while the dimerization activity remained almost the same for a period of up to 30 days time-on-stream. The loss in catalyst activity can be attributed to a higher concentration of 4-methylstyrene when the overall conversion was lower, resulting in higher dimerization and gum formation. This in turn resulted in increased catalyst deactivation compared to the case of no cyclohexene in the feed. Reactor fouling was shown to be linked to dimer and gum formation, as the pressure drop across the reactor increased with higher dimerization yield and gum formation. The increase in pressure drop was well described by a decreasing average reactor bed voidage caused by cumulative gum deposition within the catalyst bed. An overall trend of increasing gum yield with increasing dimer yield is reported, suggesting that the dimers are precursors for gum formation. In addition, catalyst deactivation was linked to carbon deposition on the catalyst caused by dimer and gum formation; increased dimer and gum formation were accompanied by an increased carbon deposition and decreased BET surface area of the catalyst. A kinetic model of the hydrogenation and dimerization of 4-methylstyrene over spent commercial Ni-Mo-S/γ-Al₂O₃ showed that hydrogenation has much lower activation energy (24.8 kJ/mol) than dimerization (68.2 kJ/mol).Applied Science, Faculty ofChemical and Biological Engineering, Department ofGraduat

A kinetic study of decalin selective ring opening reactions over Iridium supported on H-Beta zeolite catalyst

Selective ring opening of naphthenic rings is the optimum process for reducing the cyclo-paraffin and aromatic content of gas oils in order to improve its quality and consequently its value. The aim of this study was to examine the reaction rates of ring opening of a model multi-ring compound, namely decalin, using a bifunctional catalyst. Three catalysts, Pd/H-Y-30, Ir/H-Beta-300 and Ir/H-Beta-25, were tested to examine the activity and yield of ring opened products at the same reaction conditions. The reaction was performed in a continuously-stirred, batch reactor at 350°C and 3 MPa H₂ pressure. The results showed that Ir/H-Beta-25 had the highest activity and yield of ring opened products. By comparing the Ir/H-Beta-25 catalyst and the Ir/H-Beta-350 catalyst, it was concluded that higher activity was achieved with higher acidity, confirming the important role of catalyst acidity in selective ring opening. The effect of reaction conditions, namely temperature (275-350°C) and pressure (3-6 MPa), on the activity and product selectivity was also investigated. Results showed that as the temperature increased, the initial catalyst activity increased. Although the effect of pressure was minimal at 275°C, as the temperature increased, the effect of pressure became more significant and higher conversions were achieved at higher pressures. The concentration of ring opened products increased as the conversion increased for all temperatures and pressures. The ring opened product concentrations increased with increased temperature at 3 MPa. At 275°C, higher ring opened product concentrations were obtained at higher conversions as the pressure increased. Based on the experimental results, a Langmuir Hinshelwood (L-H) kinetic model for the ring opening of decalin was developed. The kinetic model assumed a bifunctional catalytic process in which hydrogenation/dehydrogenation reactions occurred on metal sites, whereas isomerization, ring-opening and cracking occurred on acid sites. The model parameters were estimated by minimizing the difference between measured experimental data and model predictions by the sum of least-squares method. The model was able to estimate the experimental results well, with a R₂ of 0.8. Activation energies estimated from the model parameters showed that ring opening had the lowest activation energy (135.4 kJ/mol), whereas cracking had the highest (229.7 kJ/mol).Applied Science, Faculty ofChemical and Biological Engineering, Department ofGraduat

Periodic INAR(1) Models with Skellam-Distributed Innovations

In this paper, an integer-valued autoregressive model of order one (INAR(1)) with time-varying parameters and driven by a periodic sequence of innovations is introduced. The proposed INAR(1) model is based on the signed thinning operator defined by Kachour and Truquet (2011) and conveniently adapted to the periodic case. Basic notations and definitions concerning the periodic signed thinning operator are provided. Based on this thinning operator, Chesneau and Kachour (2012) established a signed INAR(1) model. Motivated by the work of Chesneau and Kachour (2012), we introduce a periodic model, denoted by S-PINAR(1), with period s. In contrast to conventional INAR(1) models, these models are defined in Z allowing for negative values both for the series and its autocorrelation function. For a proper Z-valued time series, a distribution for the innovation term defined on Z is required. The S-PINAR(1) model assumes a specific innovation distribution, the Skellam distribution. Regarding parameter estimation, two methods are considered: conditional least squares and conditional maximum likelihood. The performance of the S-PINAR(1) model is assessed through a simulation study.publishe