Enhancing thermal mixing in turbulent bubbly flow by adding salt

The presence of bubbles in a turbulent flow changes the flow drastically and enhances the mixing. Adding salt to the bubbly aqueous flow changes the bubble coalescence properties as compared to pure water. Here we provide direct experimental evidence that also the turbulent thermal energy spectra are strongly changed. Experiments were performed in the Twente Mass and Heat Transfer water tunnel,in which we can measure the thermal spectra in bubbly turbulence in salty water. We find that the mean bubble diameter decreases with increasing concentration of salt (NaCl), due to the inhibition of bubble coalescence. With increasing salinity, the transition frequency from the classical $-5/3$ scaling of the thermal energy spectrum to the bubble induced $-3$ scaling shifts to higher frequencies, thus enhancing the overall thermal energy. We relate this frequency shift to the smaller size of the bubbles for the salty bubbly flow. Finally we measure the heat transport in the bubbly flow, and show how it varies with changing void fraction and salinity: Increases in both result into increases in the number of extreme events.Comment: 18 pages, 10 figures, submitted to International Journal of Multiphase Flo

Enhancing thermal mixing in turbulent bubbly flow by inhibiting bubble coalescence

The presence of bubbles in a turbulent flow changes the flow drastically and enhances the mixing. Adding salt to the bubbly aqueous flow changes the bubble coalescence properties as compared to regular demineralized water. Here we provide direct experimental evidence that also the turbulent thermal energy spectra are strongly changed. Experiments were performed in the Twente Mass and Heat Transfer water tunnel, in which we can measure the thermal spectra in bubbly turbulence in salty water. We find that the mean bubble diameter decreases with increasing concentration of salt (NaCl), due to the inhibition of bubble coalescence. With increasing salinity, the transition frequency from the classical −5/3 scaling of the thermal energy spectrum to the bubble induced −3 scaling shifts to higher frequencies, thus enhancing the overall thermal energy. We relate this frequency shift to the smaller size of the bubbles for the salty bubbly flow. Finally we measure the heat transport in the bubbly flow, and show how it varies with changing void fraction and salinity: Increases in both result into increases in the number of extreme events.</p

The emergence of bubble-induced scaling in thermal spectra in turbulence

We report on the modification of the spectrum of a passive scalar inside a turbulent flow by the injection of large bubbles. While the spectral modification through bubbles is well known and well analyzed for the velocity fluctuations, little is known on how bubbles change the fluctuations of a passive scalar. Here we uncover the thermal spectral scaling behavior of a turbulent multiphase thermal mixing layer. We trigger the development of a $-3$ spectral scaling by injecting large bubbles ($\text{Re}_{\text{bub}} = \mathcal{O}(10^2)$) with gas volume fractions up to 5\%. For these bubbly flows, the $-5/3$ scaling is still observed at intermediate frequencies but it is followed by a steeper slope for larger frequencies. This $-3$ scaling range extends with increasing gas volume fraction. The $-3$ scaling experiment coincides with the typical energy spectral scaling for the velocity fluctuations in high Reynolds number bubbly flow. We identify the frequency scale of the transition from the $-5/3$ scaling to the $-3$ scaling and show how it depends on the gas volume fraction

Genetic risk prediction of atrial fibrillation

Background—Atrial fibrillation (AF) has a substantial genetic basis. Identification of individuals at greatest AF risk could minimize the incidence of cardioembolic stroke. Methods—To determine whether genetic data can stratify risk for development of AF, we examined associations between AF genetic risk scores and incident AF in five prospective studies comprising 18,919 individuals of European ancestry. We examined associations between AF genetic risk scores and ischemic stroke in a separate study of 509 ischemic stroke cases (202 cardioembolic [40%]) and 3,028 referents. Scores were based on 11 to 719 common variants (≥5%) associated with AF at P-values ranging from &lt;1x10-3 to &lt;1x10-8 in a prior independent genetic association study. Results—Incident AF occurred in 1,032 (5.5%) individuals. AF genetic risk scores were associated with new-onset AF after adjusting for clinical risk factors. The pooled hazard ratio for incident AF for the highest versus lowest quartile of genetic risk scores ranged from 1.28 (719 variants; 95%CI, 1.13-1.46; P=1.5x10-4) to 1.67 (25 variants; 95%CI, 1.47-1.90; P=9.3x10-15). Discrimination of combined clinical and genetic risk scores varied across studies and scores (maximum C statistic, 0.629-0.811; maximum ΔC statistic from clinical score alone, 0.009-0.017). AF genetic risk was associated with stroke in age- and sex-adjusted models. For example, individuals in the highest versus lowest quartile of a 127-variant score had a 2.49-fold increased odds of cardioembolic stroke (95%CI, 1.39-4.58; P=2.7x10-3). The effect persisted after excluding individuals (n=70) with known AF (odds ratio, 2.25; 95%CI, 1.20-4.40; P=0.01). Conclusions—Comprehensive AF genetic risk scores were associated with incident AF beyond associations for clinical AF risk factors, though offered small improvements in discrimination. AF genetic risk was also associated with cardioembolic stroke in age- and sex-adjusted analyses. Efforts are warranted to determine whether AF genetic risk may improve identification of subclinical AF or help distinguish between stroke mechanisms

Risk assessment of chlorinated paraffins in feed and food

The Panel wishes to thank the hearing expert: Kerstin Krätschmer and EFSA staff member: Kelly Niermans for the support provided to this scientific output. The CONTAM Panel acknowledges all European competent institutions and other stakeholders that provided occurrence data in food and human milk and data on the toxicity of CPs, and supported the data collection for the Comprehensive European Food Consumption Database.Peer reviewedPublisher PD

Variation in the SERPINA6SERPINA1 locusalters morning plasma cortisol, hepatic corticosteroid binding globulin expression, gene expressionin peripheral tissues, and risk of cardiovascular disease

The stress hormone cortisol modulates fuel metabolism, cardiovascular homoeostasis, mood, inflammation and cognition. The CORtisol NETwork (CORNET) consortium previously identified a single locus associated with morning plasma cortisol. Identifying additional genetic variants that explain more of the variance in cortisol could provide new insights into cortisol biology and provide statistical power to test the causative role of cortisol in common diseases. The CORNET consortium extended its genome-wide association meta-analysis for morning plasma cortisol from 12,597 to 25,314 subjects and from ~2.2 M to ~7 M SNPs, in 17 population-based cohorts of European ancestries. We confirmed the genetic association with SERPINA6/SERPINA1. This locus contains genes encoding corticosteroid binding globulin (CBG) and α1-antitrypsin. Expression quantitative trait loci (eQTL) analyses undertaken in the STARNET cohort of 600 individuals showed that specific genetic variants within the SERPINA6/SERPINA1 locus influence expression of SERPINA6 rather than SERPINA1 in the liver. Moreover, trans-eQTL analysis demonstrated effects on adipose tissue gene expression, suggesting that variation

Improving tenure security for pastoralists in East Africa

PIM support to work from ILRI and partners contributed to adoption of a woreda (district) participatory land use planning approach in Ethiopia and to expansion of the joint village land use planning approach in Tanzania, resulting in more secure tenure rights for pastoralists in rangeland areas.Non-PRIFPRI1; CRP2; CRP3.7; 1 Fostering Climate-Resilient and Sustainable Food Supply; 2 Promoting Healthy Diets and Nutrition for all; 5 Strengthening Institutions and Governance; Capacity StrengtheningPIMCGIAR Research Program on Policies, Institutions, and Markets (PIM); CGIAR Research Program on Livestoc

Understanding characteristics, causes, and consequences of migration: Contributions from the CGIAR Research Program on Policies, Institutions, and Markets

It is estimated that nearly one in seven people — more than 1 billion in total — are classified as migrants in national statistics. Of these, about 763 million are estimated to be internal migrants; the remaining 281 million are international migrants (International Organization for Migration 2021). Migration is an intrinsic part of the development process, representing one of the greatest opportunities to facilitate economic and social advancement in developing countries. Understanding how different types of individuals and households perceive these opportunities and overcome related constraints, and how these change over time, is of key interest. At the same time, migration presents one of the world’s biggest challenges, requiring adjustments by both sending and hosting communities, and understanding those adjustments is a priority. The CGIAR Research Program on Policies, Institutions, and Markets (PIM) has undertaken more than 40 studies designed to explore the causes and consequences of internal and international migration. In aggregate, the studies help us understand what motivates people to migrate and what factors impinge on their ability to do so. These studies focused on the relationship of migration with rural transformation, gender, youth, climate change, and social protection and cut across the whole PIM research portfolio. This brief synthesizes findings from this research in an attempt to present a more complete picture. While there is a vast literature on migration external to PIM and CGIAR, the results of the PIM investiga­tions constitute valuable inputs into national pol­icies and programs designed to foster economic and social development while maximizing the benefits and reducing the risks of migration.Non-PRIFPRI1; CRP2; 3 Building Inclusive and Efficient Markets, Trade Systems, and Food Industry; 4 Transforming Agricultural and Rural Economies; G Cross-cutting gender themePIMCGIAR Research Program on Policies, Institutions, and Markets (PIM