Using Experimentally Validated Navier-Stokes CFD to Minimize Tidal Stream Turbine Power Losses Due to Wake/Turbine Interactions

Tidal stream turbines fixed on the seabed can harness the power of tides at locations where the bathymetry and/or coastal geography result in high kinetic energy levels of the flood and/or neap currents. In large turbine arrays, however, avoiding interactions between upstream turbine wakes and downstream turbine rotors may be hard or impossible, and, therefore, tidal array layouts have to be designed to minimize the power losses caused by these interactions. For the first time, using Navier-Stokes computational fluid dynamics simulations which model the turbines with generalized actuator disks, two sets of flume tank experiments of an isolated turbine and arrays of up to four turbines are analyzed in a thorough and comprehensive fashion to investigate these interactions and the power losses they induce. Very good agreement of simulations and experiments is found in most cases. The key novel finding of this study is the evidence that the flow acceleration between the wakes of two adjacent turbines can be exploited not only to increase the kinetic energy available to a turbine working further downstream in the accelerated flow corridor, but also to reduce the power losses of said turbine due to its rotor interaction with the wake produced by a fourth turbine further upstream. By making use of periodic array simulations, it is also found that there exists an optimal lateral spacing of the two adjacent turbines, which maximizes the power of the downstream turbine with respect to when the two adjacent turbines are absent or further apart. This is accomplished by trading off the amount of flow acceleration between the wakes of the lateral turbines, and the losses due to shear and mixing of the front turbine wake and the wakes of the two lateral turbines

A ‘machine learning’ technique for discriminating captive-reared from wild Atlantic bluefin tuna, Thunnus thynnus (Osteichthyes: Scombridae), based on differential fin spine bone resorption

The Atlantic bluefin tuna (ABFT) fishery is regulated by the International Commission for the Conservation of Atlantic Tunas (ICCAT), which establishes the allowable annual yield and the minimum capture size, and allocates capture quotas to the Contracting Parties. Despite fishery monitoring, a considerable amount of captures escapes ICCAT control. In the Mediterranean Sea, the purse seine fishery supports ABFT farming, a capture-based aquaculture activity that involves catching fish from the wild and rearing them in sea cages for a few months. The first spine of the cranial dorsal fin undergoes a continuous bone remodeling process consisting in old bone (primary bone) resorption and new bone (secondary bone) apposition. A marked increase of spine bone resorption was shown in captive-reared ABFT with respect to wild specimens. In this paper, the Random Forest (RF), a Computer Aided Detection system, was applied to distinguish captive-reared from wild ABFT based on fish age, fish fork length, total surface of spine cross section, and surface of remodeled bone tissue in the spine cross section (sum of reabsorbed bone tissue and secondary cancellous bone). The RF system was also compared to the Logistic Regression method (LR). The percentages of properly classified animals, either wild or captive-reared, with respect to the overall number of animals, i.e. accuracy, was 95.3 ± 2.6% and 79.0 ± 5.1% for RF and LR, respectively. The percentages of the properly classified captive-reared specimens, i.e. sensitivity, were 93.5 ± 3.1% and 75.8 ± 5.3% for RF and LR, respectively. The percentages of the properly classified wild specimens was 96.7 ± 2.2% and 81.4 ± 4.9%, for RF and LR, respectively. The proposed technique appears to be a reliable investigation tool anytime the suspicion arises that illegally caught ABFT are sold as aquaculture products

Pupillary effects in habitual cannabis consumers quantified with pupillography

Driving under the influence of alcohol (DUIA) and drugs (DUID) is considered an elevated risk for traffic safety. When assessing a driver's fitness to drive, standardized and objective measurement methods are still required, in order to clarify the question whether an individual is under the influence of substances acting on the central nervous system (CNS). We exposed healthy test subjects (n=41) as well as persons who were under the influence of cannabis after repeated inhalation to multiple light stimuli using infrared technology and measured the pupillary light reflex (PLR). Toxicological tests of blood samples taken from every subject followed. The aims of this study were to assess the differences in pupillography response between cannabis consumers after a washout period and no cannabis consumers as well as the dose related effects on pupillography parameters of cannabis in cannabis consumers. All four pupillary parameters changed according to a weakened pupil function after acute administration of cannabis in all test subjects. Furthermore, it could be observed that habitual cannabis consumers showed an altered pupillary function just before the first dose was taken, suggesting that the long-term effects and addiction also have to be taken into account, when effects of the CNS are discussed. The results of the present study show that almost all pupil parameters could be reliable indicators for the detection of subjects under the acute effect of cannabis

Para- and perirenal ultrasonographic fat thickness is associated with 24-hours mean diastolic blood pressure levels in overweight and obese subjects

BACKGROUND: Renal sinus fat (RSF) has been recognized as a risk factor for arterial hypertension. This study was addressed to examine whether also para- and perirenal fat accumulation is associated to higher 24-h mean systolic (SBP) and/or diastolic blood pressure (DBP) levels in overweight and obese subjects. METHODS: A cohort of 42 overweight and obese patients, 29 women and 13 men, aged 25-55 years, not treated with any kind of drug, was examined. Body mass index (BMI), waist circumference (WC), fasting insulin and glucose serum levels, insulin resistance (assessed by using the homeostasis model assessment [HOMAIR]), and 24-h aldosterone urine levels were measured. Ambulatory blood pressure monitoring (ABPM) was measured with 15 min intervals from 7.0 a.m. to 11.0 a.m. and with 30 min intervals from 23.0 to 7.0 for consecutive 24 h, starting from 8:30 AM. Measurement of para- and perirenal fat thickness was performed by ultrasounds by a duplex Doppler apparatus. RESULTS: Para- and perirenal ultrasonographic fat thickness (PUFT) was significantly and positively correlated with WC (p < 0.01), insulin (p < 0.01), HOMAIR (p < 0.01), and 24-h mean DBP levels (p < 0.05). 24-h mean DBP was also significantly and positively correlated with 24-h aldosterone urine concentrations (p < 0.001). A multivariate analysis by multiple linear regression was performed; the final model showed that the association of 24-h mean DBP as dependent variable with PUFT (multiple R = 0.34; p = 0.026) and daily aldosterone production (multiple R = 0.59; p = 0.001) was independent of other anthropometric, hormone and metabolic parameters. DISCUSSION AND CONCLUSIONS: This study shows a positive independent association between PUFT and mean 24-h diastolic blood pressure levels in overweight and obese subjects, suggesting a possible direct role of PUFT in increasing daily diastolic blood pressure

Darrieus wind turbine blade unsteady aerodynamics:a three-dimensional Navier-Stokes CFD assessment

Energized by the recent rapid progress in high-performance computing and the growing availability of large computational resources, computational fluid dynamics (CFD) is offering a cost-effective, versatile and accurate means to improve the understanding of the unsteady aerodynamics of Darrieus wind turbines, increase their efficiency and delivering more cost-effective and structurally sound designs. In this study, a Navier-Stokes CFD research code featuring a very high parallel efficiency was used to thoroughly investigate the three-dimensional unsteady aerodynamics of a Darrieus rotor blade. Highly spatially and temporally resolved unsteady simulations were carried out using more than 16,000 processor cores on an IBM BG/Q cluster. The study aims at providing a detailed description and quantification of the main three-dimensional effects associated with the periodic motion of this turbine type, including tip losses, dynamic stall, vortex propagation and blade/wake interaction. Presented results reveal that the three-dimensional flow effects affecting Darrieus rotor blades are significantly more complex than assumed by the lower-fidelity models often used for design applications, and strongly vary during the rotor revolution. A comparison of the CFD integral estimates and the results of a blade-element momentum code is also presented to highlight strengths and weaknesses of low-fidelity codes for Darrieus turbine design. The reported CFD results may provide a valuable and reliable benchmark for the calibration of lower-fidelity models, which are still key to industrial design due to their very high execution speed

Emergency total thyroidectomy due to non traumatic disease. Experience of a surgical unit and literature review

<p>Abstract</p> <p>Background</p> <p>Acute respiratory failure due to thyroid compression or invasion of the tracheal lumen is a surgical emergency requiring urgent management. The aim of this paper is to describe a series of six patients treated successfully in the emergency setting with total thyroidectomy due to ingravescent dyspnoea and asphyxia, as well as review related data reported in literature.</p> <p>Methods</p> <p>During 2005-2010, of 919 patients treated by total thyroidectomy at our Academic Hospital, 6 (0.7%; 4 females and 2 men, mean age: 68.7 years, range 42-81 years) were treated in emergency. All the emergency operations were performed for life-threatening respiratory distress. The clinical picture at admission, clinical features, type of surgery, outcomes and complications are described. Mean duration of surgery was 146 minutes (range: 53-260).</p> <p>Results</p> <p>In 3/6 (50%) a manubriotomy was necessary due to the extension of the mass into the upper mediastinum. In all cases total thyroidectomy was performed. In one case (16.7%) a parathyroid gland transplantation and in another one (16.7%) a tracheotomy was necessary due to a condition of tracheomalacia. Mean post-operative hospital stay was 6.5 days (range: 2-10 days). Histology revealed malignancy in 4/6 cases (66.7%), showing 3 primitive, and 1 secondary tumors. Morbidity consisted of 1 transient recurrent laryngeal palsy, 3 transient postoperative hypoparathyroidism, and 4 pleural effusions, treated by medical therapy in 3 and by drains in one. There was no mortality.</p> <p>Conclusion</p> <p>On the basis of our experience and of literature review, we strongly advocate elective surgery for patients with thyroid disease at the first signs of tracheal compression. When an acute airway distress appears, an emergency life-threatening total thyroidectomy is recommended in a high-volume centre.</p

Advancement study of CancerMath model as prognostic tools for predicting Sentinel lymph node metastasis in clinically negative T1 breast cancer patients

Purpose: Sentinel lymph node biopsy (SLNB) is an invasive surgical procedure and although it has fewer complications and is less severe than axillary lymph node dissection, it is not a risk-free procedure. Large prospective trials have documented SLNB that it is considered non-therapeutic in early stage breast cancer. Methods: Web-calculator CancerMath (CM) allows you to estimate the probability of having positive lymph nodes valued on the basis of tumour size, age, histologic type, grading, expression of estrogen receptor, progesterone receptor. We collected 595 patients referred to our Institute resulting clinically negative T1 breast cancer characterized by sentinel lymph node status, prognostic factors defined by CM and also HER2 and Ki-67. We have compared classification performances obtained by online CM application with those obtained after training its algorithm on our database. Results: By training CM model on our dataset and using the same feature, adding HER2 or ki67 we reached a sensitivity median value of 71.4%, 73%, 70.4%, respectively, whereas the online one was equal to 61%, without losing specificity. The introduction of the prognostic factors Her2 and Ki67 could help improving performances on the classification of particularly type of patients. Conclusions: Although the training of the model on the sample of T1 patients has brought a significant improvement in performance, the general performance does not yet allow a clinical application of the algorithm. However, the experimental results encourage future developments aimed at introducing features of a different nature in the CM model

Psychological counselling interventions to improve perceived quality of life and counter anxiety and depression in pulmonary-arterial-hypertension patients. a clinical trial

Introduction: Pulmonary Arterial Hypertension (PAH) is a rare and progressive disease, frequently associated with a worsening of perceived quality of life as well as anxiety and depression symptomatology. Psychological counselling helps the patient understand the diagnosis and prevent the onset of psychopathologies. This study evaluates the effect of counselling sessions on anxiety and depression as well as the impact on self-reported quality of life in patients with PAH. Methods: Patients with a diagnosis of PAH were recruited at the Monaldi Hospital (Naples). An EQ-5D 3L questionnaire was administered to all patients at baseline (pre-session), three months (post-session) after the last session to patients who received psychological counselling (experimental group, EG) and after the first questionnaire to patients who did not (control group, CG). The EQ-5D index and EQ-VAS score were analysed in both groups. Results: A sample of 50 patients with a PAH diagnosis was evaluated; among them 6% had mild PAH, 66% moderate PAH, and 28% severe PAH. The majority (53%) did not receive psychological counselling. All patients showed no significant difference in EQ-5D index (P &gt; 0.05), EQ-VAS score (P &gt; 0.05), and the anxiety/depression dimension (P&gt;.05) at baseline. However, between pre- and post-session evaluations, the analysis showed a significant change in the EQ-VAS score (P = 0.00) and the anxiety/depression dimension (P = 0.02) in the EG. In the CG, there was a similar change in the anxiety/depression dimension (P = 0.00) but not in the EQ-VAS score (P = 0.05) in CG. The z-test revealed significant intergroup relations, showing that the EG had a 37% increase in perceived quality of life and a 9% reduction in anxiety and depression, while a 12% reduction was observed for the CG’s perceived quality of life and a 44% increase in anxiety and depression. Discussion and Conclusions: This study showed that patients with PAH who received psychological support improved their health-related quality of life by reducing anxiety and depression symptomatology. Our findings highlight the impact of psychological support in the treatment of patients with PAH

Three-dimensional aerodynamic analysis of a Darrieus wind turbine blade using computational fluid dynamics and lifting line theory

Due to the rapid progress in high-performance computing and the availability of increasingly large computational resources, Navier-Stokes computational fluid dynamics (CFD) now offers a cost-effective, versatile and accurate means to improve the understanding of the unsteady aerodynamics of Darrieus wind turbines and deliver more efficient designs. In particular, the possibility of determining a fully resolved flow field past the blades by means of CFD offers the opportunity to both further understand the physics underlying the turbine fluid dynamics and to use this knowledge to validate lower-order models, which can have a wider diffusion in the wind energy sector, particularly for industrial use, in the light of their lower computational burden. In this context, highly spatially and temporally refined time-dependent three-dimensional Navier-Stokes simulations were carried out using more than 16,000 processor cores per simulation on an IBM BG/Q cluster in order to thoroughly investigate the three-dimensional unsteady aerodynamics of a single blade in Darrieus-like motion. Particular attention was payed to tip losses, dynamic stall, and blade/wake interaction. CFD results are compared with those obtained with an open-source code based on the Lifting Line Free Vortex Wake Model (LLFVW). At present, this approach is the most refined method among the “lower-fidelity” models and, as the wake is explicitly resolved in contrast to BEM-based methods, LLFVW analyses provide three-dimensional flow solutions. Extended comparisons between the two approaches are presented and a critical analysis is carried out to identify the benefits and drawbacks of the two approaches

Post-operative acute urinary retention after greenlight laser. Analysis of risk factors from a multicentric database

Purpose: Greenlight laser is a mini-invasive technique used to treat Benign Prostatic Obstruction (BPO). Some of the advantages of GreenLight photoselective vaporization (PVP) are shorter catheterization time and hospital stay compared to TURP. Post-operative acute urinary retention (pAUR) leads to patients' discomfort, prolonged hospital stay and increased health care costs. We analyzed risk factors for urinary retention after GreenLight laser PVP. Materials and methods: In a multicenter experience, we retrospectively analyzed the onset of early and late post-operative acute urinary retention in patients undergoing standard or anatomical PVP. The pre-, intra- and post-operative characteristics were compared betweene patients who started to void and the patients who developed post-operative urinary retention. Results: The study included 434 patients suitable for the study. Post-operative acute urinary retention occurred in 39 (9%). Patients with a lower prostate volume (P &lt; .001), an adenoma volume lower than 40 mL (P &lt; .001), and lower lasing time (P = .013) had a higher probability to develop pAUR at the univariate analysis. The multivariate logistic regression confirmed that lower lasing time (95% CI: 0.86-0.99, OR = 0.93, P = .046) and adenoma volume (95% CI: 0.89-0.98, OR = 0.94, P = .006) are correlated to pAUR. Furthermore IPSS ≥ 19 (95% CI: 1.19- 10.75, OR = 2.27, P = .023) and treatment with 5-ARI (95% CI: 1.05-15.03, OR = 3.98, P = .042) are risk factors for pAUR. Conclusion: In our series, post-operative acute urinary retention was related to low adenoma volume and lasing time, pre-operative IPSS ≥ 19 and 5-ARI intake. These data should be considered in deciding the best timing for urethral catheters removal