Comparative Analysis of Vortex-Induced Vibration Models on Risers Caused by Vessel Motion

Over the past recent years, several models for prediction of vortex-induced vibrations on risers and cables in slender marine structures have been proposed. This study provided a consistent discussion and critical evaluation of the most commonly applied models, highlighting their strengths, mathematical equations, principles, assumptions and their implications, and the apparent limitations associated with each model. The study critically evaluated and compared vortex-induced vibration models for dynamic response of water risers induced by vessel motion using a multi-criteria analysis tool (AHP). Seven alternatives which include: the DNV model, the LIC engineering model, the MARINTEK model, the MIT-Trianfyllou model, the MIT-Vandiver model, the NTH model and the UCL model were compared against a set of five broad criteria which include: Robustness, Reliability, and Accuracy, Time, Ease of application and cost. The robustness as a broad criterion contains sub-criteria like Reynold’s number range for which the simulation is valid, ability to be deployed for multimode problems, ability to describe spatial attenuation, ability to define excitation zones and how the load process is correlated in the zone. From the AHP analysis, the UCL model came out on top as the best and optimum VIV model compared to the other alternatives with an overall priority score of 1.3694. MIT-Vandiver came second with an overall priority score of 0.9656. The worst model from the outcome of the AHP analysis is the DNV model with an overall priority score of 0.6972. Keywords: vortex-induced vibration, optimum VIV model,  multi-criteria analysis tool, vortex-induced model comparison DOI: 10.7176/IEL/10-2-05 Publication date:March 31st 2020

Structural and magnetic properties of Co-Mn-Sb thin films

Thin Co-Mn-Sb films of different compositions were investigated and utilized as electrodes in alumina based magnetic tunnel junctions with CoFe counter electrode. The preparation conditions were optimized with respect to magnetic and structural properties. The Co-Mn-Sb/Al-O interface was analyzed by X-ray absorption spectroscopy and magnetic circular dichroism with particular focus on the element-specific magnetic moments. Co-Mn-Sb crystallizes in different complex cubic structures depending on its composition. The magnetic moments of Co and Mn are ferromagnetically coupled in all cases. A tunnel magneto resistance ratio of up to 24 % at 13K was found and indicates that Co-Mn-Sb is not a ferromagnetic half-metal. These results are compared to recent works on the structure and predictions of the electronic properties.Comment: 8 pages, 9 figure

A parallel group randomised open blinded evaluation of Acceptance and Commitment Therapy for depression after psychosis: Pilot trial outcomes (ADAPT)

BACKGROUND: Depression is one of the major contributors to poorer quality of life amongst individuals with psychosis and schizophrenia. The study was designed as a Pilot Trial to determine the parameters of a larger, definitive pragmatic multi-centre randomised controlled trial of Acceptance and Commitment Therapy for depression after psychosis (ACTdp) for individuals with a diagnosis of schizophrenia who also meet diagnostic criteria for major depression. METHODS: Participants were required to meet criteria for schizophrenia and major depression. Blinded follow-ups were undertaken at 5-months (end of treatment) and at 10-months (5-months posttreatment). Primary outcomes were depression as measured by the Calgary Depression Scale for Schizophrenia (CDSS) and the Beck Depression Inventory (BDI). RESULTS: A total of 29 participants were randomised to ACTdp + Standard Care (SC) (n=15) or SC alone (n=14). We did not observe significant differences between groups on the CDSS total score at 5-months (Coeff=-1.43, 95%CI -5.17, 2.32, p=0.45) or at 10-months (Coeff=1.8, 95%CI -2.10, 5.69, p=0.36). In terms of BDI, we noted a statistically significant effect in favour of ACTdp+SC at 5-months (Coeff=-8.38, 95%CI -15.49, -1.27, p=0.02) but not at 10-months (Coeff=-4.85, 95%CI -12.10, 2.39, p=0.18). We also observed significant effects on psychological flexibility at 5-months (Coeff=-8.83, 95%CI -14.94, -2.71, p<0.01) but not 10-months (Coeff=-4.92, 95%CI -11.09, 1.25, p=0.11). IMPLICATIONS: In this first RCT of a psychological therapy with depression as the primary outcome, ACT is a promising intervention for depression in the context of psychosis. A further large-scale definitive randomised controlled trial is required to determine effectiveness. TRIAL REGISTRATION: ISRCTN: 33306437

Separation of rare gases and chiral molecules by selective binding in porous organic cages

The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation

Pregnancy Exposure Registries for Assessing Antimalarial Drug Safety in Pregnancy in Malaria-Endemic Countries

Feiko ter Kuile and colleagues argue that there is an urgent need to develop targeted pharmacovigilance systems to assess the safety of antimalarials in early pregnancy

Separation of rare gases and chiral molecules by selective binding in porous organic cages

The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation

Low-dose oral theophylline combined with inhaled corticosteroids for people with chronic obstructive pulmonary disease and high risk of exacerbations: a RCT

BACKGROUND: Despite widespread use of therapies such as inhaled corticosteroids (ICSs), people with chronic obstructive pulmonary disease (COPD) continue to suffer, have reduced life expectancy and utilise considerable NHS resources. Laboratory investigations have demonstrated that at low plasma concentrations (1-5 mg/l) theophylline markedly enhances the anti-inflammatory effects of corticosteroids in COPD. OBJECTIVE: To determine the clinical effectiveness and cost-effectiveness of adding low-dose theophylline to a drug regimen containing ICSs in people with COPD at high risk of exacerbation. DESIGN: A multicentre, pragmatic, double-blind, randomised, placebo-controlled clinical trial. SETTING: The trial was conducted in 121 UK primary and secondary care sites. PARTICIPANTS: People with COPD [i.e. who have a forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) of < 0.7] currently on a drug regimen including ICSs with a history of two or more exacerbations treated with antibiotics and/or oral corticosteroids (OCSs) in the previous year. INTERVENTIONS: Participants were randomised (1 : 1) to receive either low-dose theophylline or placebo for 1 year. The dose of theophylline (200 mg once or twice a day) was determined by ideal body weight and smoking status. PRIMARY OUTCOME: The number of participant-reported exacerbations in the 1-year treatment period that were treated with antibiotics and/or OCSs. RESULTS: A total of 1578 people were randomised (60% from primary care): 791 to theophylline and 787 to placebo. There were 11 post-randomisation exclusions. Trial medication was prescribed to 1567 participants: 788 in the theophylline arm and 779 in the placebo arm. Participants in the trial arms were well balanced in terms of characteristics. The mean age was 68.4 [standard deviation (SD) 8.4] years, 54% were male, 32% smoked and mean FEV1 was 51.7% (SD 20.0%) predicted. Primary outcome data were available for 98% of participants: 772 in the theophylline arm and 764 in the placebo arm. There were 1489 person-years of follow-up data. The mean number of exacerbations was 2.24 (SD 1.99) for participants allocated to theophylline and 2.23 (SD 1.97) for participants allocated to placebo [adjusted incidence rate ratio (IRR) 0.99, 95% confidence interval (CI) 0.91 to 1.08]. Low-dose theophylline had no significant effects on lung function (i.e. FEV1), incidence of pneumonia, mortality, breathlessness or measures of quality of life or disease impact. Hospital admissions due to COPD exacerbation were less frequent with low-dose theophylline (adjusted IRR 0.72, 95% CI 0.55 to 0.94). However, 39 of the 51 excess hospital admissions in the placebo group were accounted for by 10 participants having three or more exacerbations. There were no differences in the reporting of theophylline side effects between the theophylline and placebo arms. LIMITATIONS: A higher than expected percentage of participants (26%) ceased trial medication; this was balanced between the theophylline and placebo arms and mitigated by over-recruitment (n = 154 additional participants were recruited) and the high rate of follow-up. The limitation of not using documented exacerbations is addressed by evidence that patient recall is highly reliable and the results of a small within-trial validation study. CONCLUSION: For people with COPD at high risk of exacerbation, the addition of low-dose oral theophylline to a drug regimen that includes ICSs confers no overall clinical or health economic benefit. This result was evident from the intention-to-treat and per-protocol analyses. FUTURE WORK: To promote consideration of the findings of this trial in national and international COPD guidelines. TRIAL REGISTRATION: Current Controlled Trials ISRCTN27066620. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 23, No. 37. See the NIHR Journals Library website for further project information

Assessing Model Predictions of Carbon Dynamics in Global Drylands

Drylands cover ca. 40% of the land surface and are hypothesised to play a major role in the global carbon cycle, controlling both long-term trends and interannual variation. These insights originate from land surface models (LSMs) that have not been extensively calibrated and evaluated for water-limited ecosystems. We need to learn more about dryland carbon dynamics, particularly as the transitory response and rapid turnover rates of semi-arid systems may limit their function as a carbon sink over multi-decadal scales. We quantified aboveground biomass carbon (AGC; inferred from SMOS L-band vegetation optical depth) and gross primary productivity (GPP; from PML-v2 inferred from MODIS observations) and tested their spatial and temporal correspondence with estimates from the TRENDY ensemble of LSMs. We found strong correspondence in GPP between LSMs and PML-v2 both in spatial patterns (Pearson’s r = 0.9 for TRENDY-mean) and in inter-annual variability, but not in trends. Conversely, for AGC we found lesser correspondence in space (Pearson’s r = 0.75 for TRENDY-mean, strong biases for individual models) and in the magnitude of inter-annual variability compared to satellite retrievals. These disagreements likely arise from limited representation of ecosystem responses to plant water availability, fire, and photodegradation that drive dryland carbon dynamics. We assessed inter-model agreement and drivers of long-term change in carbon stocks over centennial timescales. This analysis suggested that the simulated trend of increasing carbon stocks in drylands is in soils and primarily driven by increased productivity due to CO$_2$ enrichment. However, there is limited empirical evidence of this 50-year sink in dryland soils. Our findings highlight important uncertainties in simulations of dryland ecosystems by current LSMs, suggesting a need for continued model refinements and for greater caution when interpreting LSM estimates with regards to current and future carbon dynamics in drylands and by extension the global carbon cycle

Protocol for the proactive or reactive telephone smoking cessation support (PORTSSS) trial

Background: Telephone quit lines are accessible to many smokers and are used to engage motivated smokers to make quit attempts. Smoking cessation counselling provided via telephone can either be reactive (i.e. primarily involving the provision of evidence-based information), or proactive (i.e. primarily involving repeated, sequenced calls from and interaction with trained cessation counsellors). Some studies have found proactive telephone counselling more effective and this trial will investigate whether or not proactive telephone support for smoking cessation, delivered through the National Health Service (NHS) Smoking Helpline is more effective or cost-effective than reactive support. It will also investigate whether or not providing nicotine replacement therapy (NRT), in addition to telephone counselling, has an adjunctive impact on smoking cessation rates and whether or not this is cost effective. Methods: This will be a parallel group, factorial design RCT, conducted through the English national NHS Smoking Helpline which is run from headquarters in Glasgow. Participants will be smokers who call the helpline from any location in England and who wish to stop smoking. If 644 participants are recruited to four equally-sized trial groups (total sample size = 2576), the trial will have 90% power for detecting a treatment effect (Odds Ratio) of 1.5 for each of the two interventions: i) proactive versus reactive support and ii) the offer of NRT versus no offer. The primary outcome measure for the study is self-reported, prolonged abstinence from smoking for at least six months following an agreed quit date. A concurrent health economic evaluation will investigate the cost effectiveness of the two interventions when delivered via a telephone helpline. Discussion: The PORTSSS trial will provide high quality evidence to determine the most appropriate kind of counselling which should be provided via the NHS Smoking Helpline and also whether or not an additional offer of cost-free NRT is effective and cost effective for smoking cessation. Trial Registration: (clinicaltrials.gov): NCT0077594