Turbulent kinetic energy production in the vane of a low-pressure linear turbine cascade with incoming wakes

Copyright © 2015 V. Michelassi and J. G. Wissink. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Incompressible large eddy simulation and direct numerical simulation of a low-pressure turbine at R e = 5.18 × 10 4 and 1.48 × 10 5 with discrete incoming wakes are analyzed to identify the turbulent kinetic energy generation mechanism outside of the blade boundary layer. The results highlight the growth of turbulent kinetic energy at the bow apex of the wake and correlate it to the stress-strain tensors relative orientation. The production rate is analytically split according to the principal axes, and then terms are computed by using the simulation results. The analysis of the turbulent kinetic energy is followed both along the discrete incoming wakes and in the stationary frame of reference. Both direct numerical and large eddy simulation concur in identifying the same production mechanism that is driven by both a growth of strain rate in the wake, first, followed by the growth of turbulent shear stress after. The peak of turbulent kinetic energy diffuses and can eventually reach the suction side boundary layer for the largest Reynolds number investigated here with higher incidence angle. As a consequence, the local turbulence intensity outside the boundary layer can grow significantly above the free-stream level with a potential impact on the suction side boundary layer transition mechanism.The German Research Foundation (DFG) within the joint Project “Periodic Unsteady Flow in Turbomachinery.

RANS Turbulence Model Development using CFD-Driven Machine Learning

This paper presents a novel CFD-driven machine learning framework to develop Reynolds-averaged Navier-Stokes (RANS) models. The CFD-driven training is an extension of the gene expression programming method (Weatheritt and Sandberg, 2016), but crucially the fitness of candidate models is now evaluated by running RANS calculations in an integrated way, rather than using an algebraic function. Unlike other data-driven methods that fit the Reynolds stresses of trained models to high-fidelity data, the cost function for the CFD-driven training can be defined based on any flow feature from the CFD results. This extends the applicability of the method especially when the training data is limited. Furthermore, the resulting model, which is the one providing the most accurate CFD results at the end of the training, inherently shows good performance in RANS calculations. To demonstrate the potential of this new method, the CFD-driven machine learning approach is applied to model development for wake mixing in turbomachines. A new model is trained based on a high-pressure turbine case and then tested for three additional cases, all representative of modern turbine nozzles. Despite the geometric configurations and operating conditions being different among the cases, the predicted wake mixing profiles are significantly improved in all of these a posteriori tests. Moreover, the model equation is explicitly given and available for analysis, thus it could be deduced that the enhanced wake prediction is predominantly due to the extra diffusion introduced by the CFD-driven model.Comment: Accepted by Journal of Computational Physic

Religiosity Associated with Prolonged Survival in Liver Transplant Recipients

We tested the hypothesis that religiosity (ie, seeking God\u27s help, having faith in God, trusting in God, and trying to perceive God\u27s will in the disease) is associated with improved survival in patients with end-stage liver disease who have undergone orthotopic liver transplantation. We studied a group of 179 candidates for liver transplantation who responded to a questionnaire on religiosity during the pretransplant psychological evaluation and underwent transplantation between 2004 and 2007. The demographic data, educational level, employment status, clinical data, and results of the questionnaire were compared with the survival of patients during follow-up, regardless of the cause of any deaths. Factorial analysis of responses to the questionnaire revealed 3 main factors: searching for God (active), waiting for God (passive), and fatalism. The consistency of the matrix was very high (consistency index ? 0.92). Eighteen patients died during follow-up (median time ? 21 months). In multivariate analysis, only the searching for God factor [hazard ratio (HR) ? 2.95, 95% confidence interval (CI) ? 1.05-8.32, v2 ? 4.205, P ? 0.040] and the posttransplant length of stay in the intensive care unit (HR ? 1.05, 95% CI ? 1.01-1.08, v2 ? 8.506, P ? 0.035) were independently associated with survival, even after adjustments for the waiting for God factor, fatalism, age, sex, marital status, employment, educational level, viral etiology, Child-Pugh score, serum creatinine level, time from the questionnaire to transplantation, donor age, and intraoperative bleeding. Patients who did not present the searching for God factor were younger than those who did, but they had shorter survival times (P ? 0.037) and a 3-fold increased relative risk of dying (HR ? 3.01, 95% CI ? 1.07-8.45). In conclusion, religiosity is associated with prolonged survival in patients undergoing liver transplantation. Liver Transpl 16:1158-1163, 2010. VC 2010 AASLD

Trends of Increasing Medical Radiation Exposure in a Population Hospitalized for Cardiovascular Disease (1970-2009)

Abstract Background: High radiation doses employed in cardiac imaging may increase cancer frequency in exposed patients after decades. The aim of this study was to evaluate the relative trends in medical radiation exposure in a population hospitalized for cardiovascular disease. Methods and Results: An observational single-center study was conducted to examine 16,431 consecutive patients with heart disease admitted to the Italian National Research Council Institute of Clinical Physiology between January 1970 and December 2009. In all patients, the cumulative estimated effective dose was obtained from data mining of electronic records of hospital admissions, adopting the effective dose typical values of the American Heart Association 2009 statement and Mettler\u27s 2008 catalog of doses. Cumulative estimated effective dose per patient in the last 5 years was 22 (12-42) mSv (median, 25th-75th percentiles), with higher values in ischemic heart disease (IHD), 37 (20-59) vs non-IHD, 13 (8-22) mSv, p,0.001. Trends in radiation exposure showed a steady increase in IHD and a flat trend in non-IHD patients, with variation from 1970-74 to 2005-2009 of +155% for IHD (p,0.001) and 21% in non-IHD (NS). The relative contribution of different imaging techniques was remodeled over time, with nuclear cardiology dominating in 1970s (23% of individual exposure) and invasive fluoroscopy in the last decade (90% of individual exposure). Conclusion: A progressive increase in cumulative estimated effective dose is observed in hospitalized IHD patients. The growing medical radiation exposure may encourage a more careful justification policy regarding ionizing imaging in cardiology patients applying the two main principles of radiation protection: appropriate justification for ordering and performing each procedure, and careful optimization of the radiation dose used during each procedure

DNA content analysis of colorectal cancer defines a distinct ‘microsatellite and chromosome stable’ group but does not predict response to radiotherapy

Colorectal cancers (CRC) are thought to have genetic instability in the form of either microsatellite instability (MSI) or chromosomal instability (CIN). Recently, tumours have been described without either MSI or CIN, that is, microsatellite and chromosome stable (MACS) CRCs. We investigated the (i) frequency of the MACS-CRCs and (ii) whether this genotype predicted responsiveness to neoadjuvant chemoradiotherapy. To examine the frequency of MACS-CRCs, DNA content (ploidy) was examined in 89 sporadic microsatellite-stable CRCs using flow cytometry. The tumours were also screened for mutations in KRAS/BRAF/TP53/PIK3CA by QMCPCR. To examine the value of tumour ploidy in predicting response to chemoradiotherapy, DNA content was tested in a separate group of 62 rectal cancers treated with neoadjuvant chemoradiotherapy. Fifty-one of 89 CRCs (57%) were aneuploid and 38 (43%) were diploid. There was no significant association between mutations in TP53/KRAS/BRAF/PIK3CA and ploidy. Testing of association between mutations revealed only mutual exclusivity of KRAS/BRAF mutation (P < 0.001). Of the 62 rectal cancers treated with neoadjuvant chemoradiotherapy, 22 had responded (Mandard tumour regression grade 1/2) and 40 failed to respond (Grade 3–5). Twenty-five of 62 (40%) tumours were diploid, but there was no association between ploidy and response to therapy. We conclude that MACS-CRCs form a significant proportion of microsatellite-stable CRCs with a mutation profile overlapping that of CRCs with CIN. A diploid genotype does not, however, predict the responsiveness to radiotherapy

Crohn's disease activity index and Vienna classification - Is it worthwhile to calculate before surgery?

Background: Crohn's disease (CD) patients with increased disease activity may reveal an increased risk for perioperative complications. The `Crohn's disease activity index' (CDAI) and the `Vienna classification' (VC) were developed for standardized disease activity estimations. The significance of these scores to predict extent, type and early outcome of surgery in CD patients was analyzed. Methods: In 179 surgically treated CD patients, the CDAI and VC were assessed from a prospective database. Relations of the scores with CD risk factors, type, number, location and complications of surgery were analyzed. Results: VC behavior and location subtypes were associated with distinct types of surgery (i.e. `strictureplasty' in `stricturing disease', `colon surgery' in `colon involvement'), but not with surgery type and extent or outcome. Surgery extent (i.e. with 5 vs. 3 `surgical sites' 425 +/- 25 vs. 223.3 +/- 25) and complications (357.1 +/- 36.9 (with) vs. 244.4 +/- 13 (without)) were associated with elevated CDAI levels; however, nicotine abuse remained the only significant risk factor for perioperative complications after multiple logistic regression. Conclusion: The significance of VC or CDAI for predicting the extent of surgery or complications is limited. None of the tested variables except preoperative nicotine abuse influenced the likelihood for perioperative complications. Copyright (c) 2006 S. Karger AG, Base

The Effect of wake Turbulence Intensity on Transition in a Compressor Cascade

Direct numerical simulations of separating flow along a section at midspan of a low-pressure V103 compressor cascade with periodically incoming wakes were performed. By varying the strength of the wake, its influence on both boundary layer separation and bypass transition were examined. Due to the presence of small-scale three-dimensional fluctuations in the wakes, the flow along the pressure surface undergoes bypass transition. Only in the weak-wake case, the boundary layer reaches a nearly-separated state between impinging wakes. In all simulations, the flow along the suction surface was found to separate. In the simulation with the strong wakes, separation is intermittently suppressed as the periodically passing wakes managed to trigger turbulent spots upstream of the location of separation. As these turbulent spots convect downstream, they locally suppress separation. © 2014 Springer Science+Business Media Dordrecht

Gas turbulence modulation in a two-fluid model for gas-solid flows

Recent rapid progress in the theoretical and experimental study of turbulence modulation has led to greater understanding of the physics of particle-gas turbulence interactions. A new two-fluid model incorporating these advances for relatively dilute gas-solid flows containing high-inertia particles is established. The effect of aerodynamic forces upon the particulate stresses is considered in this kinetic theory-based model, and the influence of the particles on the turbulent gas is addressed: the work associated with drag forces contributes to the gas turbulent energy, and the space occupied by particles restricts the turbulent length scale. The interparticle length scale, which is usually ignored, has been incorporated into a new model for determining the turbulent length scale. This model also considers the transport effect on the turbulent length scale. Simulation results for fully developed steady flows in vertical pipes are compared with a wide range of published experimental data and, generally, good agreement is shown. This comprehensive and validated model accounts for many of the interphase interactions that have been shown to be important

STATO DI SALUTE DELLE POPOLAZIONI RESIDENTI NELLE AREE GEOTERMICHE DELLA TOSCANA

Objective The limited scientific knowledge on relationship between exposure and health effects in relation to geothermal activity motivated an epidemiologic investigation in Tuscan geothermal area. The study aims to describe the health status of populations living in Tuscany municipalities where concessions for exploitation of geothermal resources were granted. Design This is an ecological study, so it is not useful to produce evidence to sustain a judgment on the cause-effect link. The major limits of this type of study are the use of the residence at municipal level as a proxy of exposure to both environmental and socioeconomic factors and the use of aggregated data of health outcomes that can lead to the well-known ecological fallacy. Setting and participants Sixteen municipalities were included in the study area: eight are part of the so-called "traditional" geothermal area, defined as Northern Geothermal Area (NGA) and eight located in the Amiata Mountain defined as Southern Geothermal Area (SGA). In 2000-2006, the average resident population in the overall area was approximately 43,000 inhabitants. Thirty-one geothermal power plants were active, with a production capacity of 811 MW, 5 of them with 88 MW located in the SGA. Statistical analyses on the entire geothermal area, NGA and SGA subareas, and the sixteen municipalities were performed. Main outcome measures Mortality data were obtained from Tuscany Regional Mortality Registry for the 1971-2006 period, analysing 60 causes of death, of interest for population health status or consistent with "Project SENTIERI" criteria. Hospital discharge records of residents in Tuscany Region in 2004-2006, anywhere admitted to hospital, were analyzed considering only the main diagnosis, excluding repeated admissions for the same cause. The causes taken into account are the same analysed for mortality were considered. Age-standardized mortality rates (TSDM) and the temporal trends of TSDM for four periods (1971-1979, 1980- 1989, 1990-1999, 2000-2006) were computed. Age-standardized mortality/hospitalization ratios (SMR/SHR), with and without adjustment for the deprivation index based on 2001 census data, were calculated: mortality in the years 2000-2006 and hospitalization in 2004-2006. The expected number of events were computed using rates of residents in neighbouring municipalities (municipalities included in 50 km radius circle centred on the study area). Bayesian estimates of mortality/hospitalization ratios (BMR/BHR) at municipal level only and relating maps of the Bayesian risk estimators were elaborated. Congenital malformations (MC) were analysed using data from Tuscan Registry of Birth Defect in 1992-2006 period, relative to outcomes of pregnancies in women resident in the municipalities of study area, wherever the birth or termination of pregnancy occurred. The ratio between observed and expected cases (O/A), with expected defined according to regional rate, were calculated and O/A Bayesian estimates (BMR) are showed only at municipal level . The low weight and the males/females ratio at birth were analysed using data from Tuscany Birth Certificates, covering period 2001-2007, excluding biths occurred in facilities outside Tuscany Region. For Low birth weight (<2,500 grams), very low birth weight (<1,500 grams), low birth weight in women with normal gestational age or greater than 36 weeks, gestational age less than 36 weeks, and the frequency of males, the observed/expected ratio was calculated, with the expected number defined according to regional rate. Results Environmental background High levels of arsenic in drinking water distribution emerges as a critical element, so that several municipalities resorted to granting exemptions for the parameters laid down by the Legislative Decree in force (DLgs 31/01). However, during the final phase of the study, new blast systems activated in the SGA decreased the arsenic levels in the water supply, reaching values not requiring derogations, which, instead, are still effective in some NGA municipalities. Air quality data, from Tuscany Regional Agency for Environmental Protection-ARPAT, show that geothermal activities are able to affect air quality, especially with hydrogen sulphide in NGA, and hydrogen sulphide and mercury in SGA. A significant contribution to the presence of mercury in air is due to previous metallurgical sites. Although mercury levels are belowWHO guideline values, in SGA nearby Siena, values were significantly higher than in other geothermal areas, because of power plant PC2 (turned off in July 2011) in Piancastagnaio municipality. The hydrogen sulphide concentration levels were generally lower than WHO reference values, with occasional excesses over guideline value for health protection (150 &#956;g/m3 as average of the 24 hours). Olfactory pollution was more critic with values exceeding 7-10 &#956;g/m3 range even in areas without geothermal plants.Obiettivo Le limitate conoscenze scientifiche sui rapporti tra esposizione a fattori ambientali correlati all\u27attivit? geotermica e lo stato di salute della popolazione esposta hanno motivato la conduzione di una indagine epidemiologica nell\u27area geotermica toscana basata sull\u27analisi dei dati ambientali e sanitari disponibili negli archivi regionali. Lo studio ha lo scopo di descrivere lo stato di salute delle popolazioni residenti nelle aree geotermiche toscane, identificate con i territori comunali per i quali sono state rilasciate concessioni di sfruttamento della risorsa geotermica. Disegno Lo studio ? di tipo ecologico e quindi non adatto a produrre evidenze che permettano di esprimere un giudizio sul nesso causa-effetto. I maggiori limiti degli studi ecologici derivano dall\u27assunzione che la residenza anagrafica a livello comunale rappresenti una valida misura di esposizione a fattori sia ambientali sia socioeconomici e dall\u27utilizzo di dati aggregati degli esiti sanitari che possono portare a risultati affetti da fallacia ecologica. Setting e partecipanti I comuni inclusi nell\u27area geotermica dello studio sono 16, di cui 8 compresi nell\u27area geotermica cosiddetta ?tradizionale?, che include le localit? di Larderello, Val di Cornia e Radicondoli-Travale (area geotermica Nord) e gli altri 8 situati nella zona dell\u27Amiata senese e grossetana (area geotemica Sud). Nel periodo 2000-2006 la popolazione media residente nell\u27area geotermica complessiva era di oltre 43.000 abitanti. Al momento dello studio erano attive 31 centrali geotermoelettriche con capacit? di produzione di 811 MW, di cui 5 con 88 MW totali nell\u27area geotermica Sud. Le analisi statistiche sono state effettuate a livello di intera area geotermica, delle due subaree geotermiche (Nord e Sud) e dei 16 comuni. Principali misure di outcome La mortalit? ? stata analizzata utilizzando i dati del Registro di mortalit? regionale della Toscana per l\u27intero periodo disponibile (1971-2006), con dettaglio per 60 cause, scelte in quanto di interesse generale per il profilo di salute della popolazione o perch? coerenti con i criteri adottati dal Progetto SENTIERI. L\u27ospedalizzazione ? stata valutata analizzando i dati delle schede di dimissione ospedaliera (SDO) della Re-gione Toscana nel periodo 2004-2006, includendo i ricoverati residenti in Toscana ovunque abbiano effettuato un ricovero, considerando solo la diagnosi principale di ricovero, escludendo i ricoveri ripetuti degli stessi soggetti per la stessa causa. Le cause di ospedalizzazione selezionate per l\u27analisi dei ricoveri sono le stesse utilizzate per l\u27analisi della mortalit?. Per la mortalit? sono stati calcolati i tassi di mortalit? standardizzati per et? (TSDM) e i trend temporali dei TSDM in quattro periodi (1971- 1979, 1980-1989, 1990-1999, 2000-2006). Sia per la mortalit? del periodo 2000-2006, sia per l\u27ospedalizzazione del periodo 2004-2006,sono stati calcolati: &#61692; i rapporti di mortalit?/ospedalizzazione standardizzati per et? (SMR/SHR), con e senza aggiustamento per l\u27indice di deprivazione (ID), utilizzando per il calcolo dell\u27ID i dati del censimento 2001, con gli attesi calcolati usando il tasso di mortalit?/ospedalizzazione della popolazione residente nei comuni limitrofi (comuni con la coordinata geografica del municipio compresa in un cerchio con raggio di 50 km centrato sull\u27area in studio); &#61692; le stime bayesiane dei rapporti di mortalit? (BMR) e di ospedalizzazione (BHR) a livello esclusivamente comunale; &#61692; le mappe (disease mapping) dei rischi bayesiani di mortalit?/ospedalizzazione comunali. Le malformazioni congenite (MC) sono state analizzate utilizzando i dati del Registro toscano dei difetti congeniti (RTDC) nel periodo 1992-2006, relativi a esiti di gravidanze di donne residenti nei comuni dell\u27area in studio, ovunque sia avvenuto il parto o l\u27interruzione di gravidanza. Per le MC ? stato calcolato il rapporto tra casi osservati e casi attesi (O/A), con gli attesi definiti in base al tasso regionale e vengono fornite le stime bayesiane del rapporto O/A (BMR) a livello esclusivamente comunale. Per valutare il basso peso e il rapporto tra maschi e femmine alla nascita sono stati utilizzati i dati dei certificati di assistenza al parto della Regione Toscana, relativi al periodo 2001-2007, con esclusione degli eventi occorsi in presidi di altre regioni. L\u27analisi ? stata condotta considerando i nati con: basso peso alla nascita (LW: peso <2.500 grammi), bassissimo peso alla nascita (VLW: peso <1.500 grammi), basso peso alla nascita nelle donne con et? gestazionale normale e maggiore di 36 settimane (LW36), et? gestazionale inferiore a 36 settimane, e il numero di maschi osservato. Per tutti gli indicatori ? stato calcolato il rapporto osservato/atteso, con l\u27atteso definito in base al tasso regionale. Risultati Il contesto ambientale Dalla descrizione del contesto ambientale, per quanto riguarda l\u27acqua, emerge come elemento di criticit? il riscontro talvolta di elevati livelli di arsenico nelle acque della rete di distribuzione degli acquedotti, tanto che in diverse realt? comunali si ? dovuto far ricorso alla concessione di deroghe ai parametri previsti dal decreto legislativo vigente (DLgs 31/01). Comunque, durante la fase conclusiva dello studio, nell\u27area geotermica Sud i nuovi sistemi abbattitori hanno ridotto i livelli di arsenico nella rete idrica fino a valori tali da non dover pi? ricorrere alle deroghe, ancora attive, invece, in alcuni comuni dell\u27area geotermica Nord. Le informazioni dell\u27ARPAT sui dati dell\u27aria evidenziano che l\u27attivit? geotermica ? in grado di modificare la qualit? dell\u27aria, soprattutto per l\u27acido solfidrico nell\u27area geotermica Nord, e per l\u27acido solfidrico e il mercurio nell\u27area geotermica Sud, in particolare nel versante senese dell\u27Amiata. Per il mercurio nell\u27aria, un contributo rilevante ? legato anche alle emissioni dagli ex siti metallurgici. Sebbene i livelli di mercurio nelle postazioni di monitoraggio rientrino sempre al di sotto dei valori guida raccomandati dall\u27OMS, le concentrazioni riscontrate nell\u27aria dell\u27Amiata senese, e perlopi? legate alla centrale PC2 di Piancastagnaio (spenta nel luglio 2011), sono significativamente superiori a quelle rilevate nelle altre aree geotermiche che, al contrario, sono assestate sugli stessi livelli registrati nei territori non geotermici. I livelli di concentrazione di acido solfidrico sono inferiori ai valori di riferimento, con occasionali superamenti del valore guida di tutela sanitaria OMS (150 &#956;g/m3 come media delle 24 ore). Pi? critici sono i dati di inquinamento olfattivo, che si verifica con il superamento del valore di 7-10 g/m3 di acido solfidrico nell\u27aria, riscontrato con vario grado di intensit? in tutte le postazioni di monitoraggio, anche in aree dove non sono presenti impianti geotermici. In alcune aree con insediamenti produttivi geotermici la frequenza, la persistenza e l\u27intensit? dei cattivi odori sono tali da comportare condizioni di qualit? dell\u27aria scadente