7,277 research outputs found

    A New Equation of State for CCS Pipeline Transport: Calibration of Mixing Rules for Binary Mixtures of CO2 with N2, O2 and H2

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    One of the aspects currently holding back commercial scale deployment of carbon capture and storage (CCS) is an accurate understanding of the thermodynamic behaviour of carbon dioxide and relevant impurities during the pipeline transport stage. In this article we develop a general framework for deriving pressure-explicit EoS for impure CO2. This flexible framework facilitates ongoing development of custom EoS in response to new data and computational applications. We use our method to generalise a recent EoS for pure CO2 [Demetriades et al. Proc IMechE Part E, 227 (2013) pp. 117] to binary mixtures with N2, O2 and H2, obtaining model parameters by fitting to experiments made under conditions relevant to CCS-pipeline transport. Our model pertains to pressures up to 16MPa and temperatures between 273K and the critical temperature of pure CO2. In this region, we achieve close agreement with experimental data. When compared to the GERG EoS, our EoS has a comparable level of agreement with CO2 -N2 VLE experiments and demonstrably superior agreement with the O2 and H2 VLE data. Finally, we discuss future options to improve the calibration of EoS and to deal with the sparsity of data for some impurities

    A concurrent precursor inflow method for Large Eddy Simulations and applications to finite length wind farms

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    In order to enable simulations of developing wind turbine array boundary layers with highly realistic inflow conditions a concurrent precursor method for Large Eddy Simulations is proposed. In this method we consider two domains simultaneously, i.e. in one domain a turbulent Atmospheric Boundary Layer (ABL) without wind turbines is simulated in order to generate the turbulent inflow conditions for a second domain in which the wind turbines are placed. The benefit of this approach is that a) it avoids the need for large databases in which the turbulent inflow conditions are stored and the correspondingly slow I/O operations and b) we are sure that the simulations are not negatively affected by statically swept fixed inflow fields or synthetic fields lacking the proper ABL coherent structures. Sample applications are presented, in which, in agreement with field data a strong decrease of the power output of downstream wind-turbines with respect to the first row of wind-turbines is observed for perfectly aligned inflow.Comment: 13 pages, 5 figure

    An Infrared Camera for Leuschner Observatory and the Berkeley Undergraduate Astronomy Lab

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    We describe the design, fabrication, and operation of an infrared camera which is in use at the 30-inch telescope of the Leuschner Observatory. The camera is based on a Rockwell PICNIC 256 x 256 pixel HgCdTe array, which is sensitive from 0.9-2.5 micron. The primary purpose of this telescope is for undergraduate instruction. The cost of the camera has been minimized by using commercial parts whereever practical. The camera optics are based on a modified Offner relay which forms a cold pupil where stray thermal radiation from the telescope is baffled. A cold, six-position filter wheel is driven by a cryogenic stepper motor, thus avoiding any mechanical feed throughs. The array control and readout electronics are based on standard PC cards; the only custom component is a simple interface card which buffers the clocks and amplifies the analog signals from the array.Comment: 13 pages, 17 figures. Submitted to Publications of the Astronomical Society of the Pacific: 2001 Jan 10, Accepted 2001 Jan 1

    Condoms are more effective when applied by males: a study of young black males in the United States

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    PurposeTo determine, among a sample of young black male (YBM), whether female application of male condoms for penile–vaginal intercourse would be associated with higher or lower rates of breakage or slippage. A secondary aim was to investigate if higher rates of breakage or slippage were associated with increased odds of acquiring chlamydia and/or gonorrhea.MethodsA cross-sectional study of 412 YBM, aged 15 to 23 years, was conducted in three US cities located in the Southern United States.ResultsAmong YBM reporting frequent female application of condoms, 43.5% reported one or more instance of breakage or slippage, compared with those reporting less frequent female application (27.2%, P = .003). Among YBM reporting one or more event of breakage or slippage, 25.4% tested positive for chlamydia and/or gonorrhea. In contrast, among those not reporting breakage or slippage, 17.2% tested positive (P = .047).ConclusionsFindings suggest that educational and behavioral interventions should seek to improve young women's skills relative to condom application and use. Further studies could also investigate whether intervention efforts should encourage some YBM to be responsible for their own condom application

    Coarse-grained simulations of flow-induced nucleation in semi-crystalline polymers

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    We perform kinetic Monte Carlo simulations of flow-induced nucleation in polymer melts with an algorithm that is tractable even at low undercooling. The configuration of the non-crystallized chains under flow is computed with a recent non-linear tube model. Our simulations predict both enhanced nucleation and the growth of shish-like elongated nuclei for sufficiently fast flows. The simulations predict several experimental phenomena and theoretically justify a previously empirical result for the flow-enhanced nucleation rate. The simulations are highly pertinent to both the fundamental understanding and process modeling of flow-induced crystallization in polymer melts.Comment: 17 pages, 6 eps figure

    Impact of caring for someone with a rare rheumatic condition, views from patients and informal carers – the need for cat-like vigilance

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    Objective ANCA-associated vasculitis (AAV) is a rare multisystem disease. Modern therapeutic protocols have turned AAV from an acute frequently fatal disease into a chronic disease requiring long-term immunosuppression. Patients must often manage substantial burdens related to chronic illness and treatment-related side effects, requiring help from informal carers. This study aimed to explore the experience of patients and of informal carers of patients with AAV about the impact of managing a rare rheumatic condition. Methods A qualitative approach using semi-structured interviews was used. Interviews were conducted with a purposeful sample of 18 pairs of patients with AAV and their informal carers. The interviews were used to explore the participants’ experience and effects of caring. The interviews were recorded and transcribed as verbatim text and analysed using the framework technique. Results 18 patients (seven female) [disease: ten granulomatosis with polyangiitis (GPA); four microscopic polyangiitis (MPA); four eosinophilic granulomatosis with polyangiitis (EGPA), age range 34-78, disease duration 1- 20 years. Caregiver and patient perspectives were shared. The emerging themes were the physical and psychological impact of the disease, the need for constant vigilance and fear of the future. Conclusion Both patients and carers faced a range of challenges in managing a rare condition, from the seriousness of the illness, dealing with the emotional toll and knowing what to expect. This study offers insight into the experiences of patients and informal carers, and health care professionals should address individuals’ fears and expectations for recovery

    Investigating intra-host and intra-herd sequence diversity of foot-and-mouth disease virus

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    Due to the poor-fidelity of the enzymes involved in RNA genome replication, foot-and-mouth disease (FMD) virus samples comprise of unique polymorphic populations. In this study, deep sequencing was utilised to characterise the diversity of FMD virus (FMDV) populations in 6 infected cattle present on a single farm during the series of outbreaks in the UK in 2007. A novel RT–PCR method was developed to amplify a 7.6 kb nucleotide fragment encompassing the polyprotein coding region of the FMDV genome. Illumina sequencing of each sample identified the fine polymorphic structures at each nucleotide position, from consensus level changes to variants present at a 0.24% frequency. These data were used to investigate population dynamics of FMDV at both herd and host levels, evaluate the impact of host on the viral swarm structure and to identify transmission links with viruses recovered from other farms in the same series of outbreaks. In 7 samples, from 6 different animals, a total of 5 consensus level variants were identified, in addition to 104 sub-consensus variants of which 22 were shared between 2 or more animals. Further analysis revealed differences in swarm structures from samples derived from the same animal suggesting the presence of distinct viral populations evolving independently at different lesion sites within the same infected animal

    275 Impact of caring for someone with a rare rheumatic condition: views from patients and informal carers

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    Background: ANCA-associated vasculitis is a rare multisystem disease. Modern therapeutic protocols have turned ANCA-associated vasculitis from an acute frequently fatal disease into a chronic disease requiring long-term immunosuppression. Patients must often manage substantial burdens related to chronic illness and treatment-related side effects. Patients often need help and support to manage their disease. The aim of this study was to explore the experience of patients and of informal carers of patients about the impact of managing a rare rheumatic condition. Methods: A qualitative approach using semi-structured interviews was used. Interviews were conducted with a purposeful sample of 18 pairs of patients with ANCA-associated vasculitis and their informal carers. The interviews were used to explore the participants experience and affects of caring. The interviews were recorded and transcribed as verbatim text and analysed using the framework technique. Results: 18 patients (seven female) [disease: ten granulomatosis with polyangiitis (GPA); four microscopic polyangiitis (MPA); four eosinophilic granulomatosis with polyangiitis (EGPA), age range 34-78, disease duration 1- 20 years. Caregiver and patient perspectives were shared. The emerging themes were the physical and psychological impact of the disease, the need for constant vigilance and fear of the future. Conclusion: Both patients and carers faced a range of challenges in managing a rare condition. From the seriousness of the illness, dealing with the emotional toll and knowing what to expect. This study offers insight into the experiences of patients and informal carers and health care professionals should address individuals’ fears and expectations for recovery. Disclosures: J.M. honoraria; Abbvie, Bristol Myres Squibb. K.G. and R.A.W. have declared no conflicts of interest
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