From gloom to doom: Financial loss and negative affect prime risk averse preferences

Previous research has shown that risk preferences are sensitive to the financial domain in which they are framed. In the present study we explore whether the effect of valence priming on risk taking is moderated by the financial context under consideration. A total of 260 participants completed an online questionnaire where risky choices were elicited for seven different financial scenarios. Participants were allocated to different valence (neutral, positive or negative) and arousal (low or high) priming conditions. Two factors were extracted: Factor 1 (Negative) included insurance and possibility of loss, whilst Factor 2 (Positive) included the remaining five scenarios (investment, salary, pension, possibility of gain, and mortgage). Moreover, only negative priming—regardless of arousal level—influenced people’s risky choices by inducing more risk-averse behavior; this effect was confined only to loss and insurance domains. The findings call into question the generalizability of priming effects on different financial context and show that the effects of priming on financial risk taking are sensitive to the financial context under consideration

CFD – facilitated Prognosis of Bubble Bed Bioreactor Performance Based on Bubble Swarms Oscillation Analysis

Bubble column reactors are widely used as gas-liquid and gas liquid-solid contactors in biotechnology applications. A basic issue in biotechnology is oxygen availability related to gas hold-up distribution, since aerobic bioprocessing depends on the dissolved oxygen substrate. The aim of this study is to analyze oxygen availability in bubble column bioreactors in terms of specific spatial and temporal gas-liquid flow. 3D CFD simulation is used to simulate the dispersed gas-liquid flow field of a bubble column of ID 0.29 m equipped with metal distributing plate. The solution is based on the Euler/Euler approach, the standard k-ε model, and the standard wall function treatment. A single size particle model was employed. No mass transfer between the gas and the liquid phase was studied; oxygen transfer is discussed in terms of local and temporal gas hold-up distribution. Two cases of different viscosity are studied related to water-like and sugar-containing nutrient media cases, e.g. tap water and aqueous solution of 0.3 kg kg–1 saccharose, respectively. Conditions of oxygen availability for aerobic cell growth in a bio-fluid at condition of elevated viscosity are considered. The time-course of instantaneous oxygen delivery proportional to the dispersion capacity estimated as gas hold-up is uncovered. The results are presented in the form of contour plots and radial profiles of the local gas hold-up at different bed height positions. The oscillating behaviour of the gas hold-up is illustrated and summarized into oxygen availability plot related to position. Based on the CFD analysis, clues for rational bioprocess performance time-course could be inferred

CFD – facilitated Prognosis of Bubble Bed Bioreactor Performance Based on Bubble Swarms Oscillation Analysis

Bubble column reactors are widely used as gas-liquid and gas liquid-solid contactors in biotechnology applications. A basic issue in biotechnology is oxygen availability related to gas hold-up distribution, since aerobic bioprocessing depends on the dissolved oxygen substrate. The aim of this study is to analyze oxygen availability in bubble column bioreactors in terms of specific spatial and temporal gas-liquid flow. 3D CFD simulation is used to simulate the dispersed gas-liquid flow field of a bubble column of ID 0.29 m equipped with metal distributing plate. The solution is based on the Euler/Euler approach, the standard k-ε model, and the standard wall function treatment. A single size particle model was employed. No mass transfer between the gas and the liquid phase was studied; oxygen transfer is discussed in terms of local and temporal gas hold-up distribution. Two cases of different viscosity are studied related to water-like and sugar-containing nutrient media cases, e.g. tap water and aqueous solution of 0.3 kg kg–1 saccharose, respectively. Conditions of oxygen availability for aerobic cell growth in a bio-fluid at condition of elevated viscosity are considered. The time-course of instantaneous oxygen delivery proportional to the dispersion capacity estimated as gas hold-up is uncovered. The results are presented in the form of contour plots and radial profiles of the local gas hold-up at different bed height positions. The oscillating behaviour of the gas hold-up is illustrated and summarized into oxygen availability plot related to position. Based on the CFD analysis, clues for rational bioprocess performance time-course could be inferred

Domain effects and financial risk attitudes

We investigated whether financial risk preferences are dependent on the financial domain (i.e., the context) in which the risky choice options are presented. Previous studies have demonstrated that risk attitudes change when gambles are framed as gains, losses, or as insurance. Our study explores this directly by offering choices between identical gambles, framed in terms of seven financial domains. Three factors were extracted, explaining 68.6% of the variance: Factor 1 (Positive)—opportunity to win, pension provision, and job salary change; Factor 2 (Positive-Complex)—investments and mortgage buying; Factor 3 (Negative)—possibility of loss and insurance. Inspection of the solution revealed context effects on risk perceptions across the seven scenarios. We also found that the commonly accepted assumption that women are more risk averse cannot be confirmed with the context structure suggested in this research; however, it is acknowledged that in the students’ population the variance across genders might be considerably less. These results suggest that our financial risk attitude measures may be tapping into a stable aspect of “context dependence” of relevance to real-world decision making

Electronic States in Diffused Quantum Wells

In the present study we calculate the energy values and the spatial distributions of the bound electronic states in some diffused quantum wells. The calculations are performed within the virtual crystal approximation, $sp^3 s^*$ spin dependent empirical tight-binding model and the surface Green function matching method. A good agreement is found between our results and experimental data obtained for AlGaAs/GaAs quantum wells with thermally induced changes in the profile at the interfaces. Our calculations show that for diffusion lengths $L_{D}=20\div100$ {\AA} the transition (C3-HH3) is not sensitive to the diffusion length, but the transitions (C1-HH1), (C1-LH1), (C2-HH2) and (C2-LH2) display large "blue shifts" as L_{D} increases. For diffusion lengths $L_{D}=0\div20$ {\AA} the transitions (C1-HH1) and (C1-LH1) are less sensitive to the L_{D} changes than the (C3-HH3) transition. The observed dependence is explained in terms of the bound states spatial distributions.Comment: ReVTeX file, 7pp., no macros, 4 figures available on the reques

Agitation Effects and Kinetic Constants of Exoglucomannan Production by Antarctic Yeast Strain in a Stirred Tank Bioreactor

Exoglucomannan production by Antarctic yeast Sporobolomyces salmonicolor AL1 is studied at semi-tech scale in a 5 L stirred tank bioreactor and the bioreaction kinetics is quantified. The organism’s unconventional response to agitation is analyzed in terms of the agitation-induced mechanical stress. The yeast maximum production activity was observed at agitation rate 400 rpm and conserved or decreased at further increase in mixing intensity. Referring to the relationship of cell growth and aeration intensity, the various production activity, oxygen availability and cell growth are considered as a starting point to elucidate the possible reasons for the anomaly. At suspicion of shear detrimental effect on the yeast cells, the hydrodynamic stress acting on cell particles is determined and the microorganism morphology at low and high mixing intensity is examined. Biological stability is registered and the agitation effect is attributed to depressed metabolic activity at the evolving dissolved oxygen tension rather than to direct effect of hydrodynamics. A kinetic model is proposed. The specific growth rate (µ, h–1) and growth-associated (g EPS g–1 cells), and non-growth associated (g EPS g–1 cells h–1) production constants are determined and compared with reported estimates for similar reference EPS fermentations. The model and its parameters are determined in well-mixed cultures and could be upgraded further to account for mixing non-ideality and mass transfer in larger vessels

Calculations of the Local Density of States for some Simple Systems

A recently proposed convolution technique for the calculation of local density of states is described more thouroughly and new results of its application are presented. For separable systems the exposed method allows to construct the ldos for a higher dimensionality out of lower dimensional parts. Some practical and theoretical aspects of this approach are also discussed.Comment: 5 pages, 3 figure

Fluid Flow Properties of Slotted Flat- and Hollow-blade Impellers

Published data on flow field variation caused by various blade design patterns are scarce. Most designs exhibit significant flow separation and adverse pressure gradients effects that lower mixing efficiency. In view of the design potentials of the CFD methodology, the flow field variations caused by different blade designs could be classified in order to be able to predict the spread of the low pressure regions behind blades while retrofitting existing equipment towards energy-saving performance without decreasing the impeller blending and dispersing capacity related to the geometry considered. The aim of the present study is to reveal such variations for some conventional flat blade modifications. The performance of three flat and hollow blade design modifications comprising slotted and perforated blades are examined. The specific power drawn, pumping capacity, deformation rate and turbulence intensity are determined and compared. The impeller power effectiveness is discussed in terms of the strain deformation rate produced. Evidence for enhanced performance of slotted and perforated designs is presented

What motivates primary healthcare practitioners to refer patients with Chronic Obstructive Pulmonary Disease (COPD) to Pulmonary Rehabilitation? A survey using the Theoretical Domains Framework

Background: Pulmonary rehabilitation (PR) is a highly effective intervention for patients with COPD but primary care referral rates are persistently low. The Theoretical Domains Framework (TDF) provides a structure for identifying motivators for behaviour change. Aim: Using the TDF to identify & classify the key barriers and enablers for UK primary healthcare practitioners (PHPs) when referring patients with COPD to PR. Methodology: A 54-item questionnaire, derived from our previous qualitative study and guided by the TDF, was distributed to UK based PHPs. Participants were recruited by e-mail (Primary Care Respiratory Society members), social media or direct targeting of participants at PHP conferences. Descriptive statistics were used to analyse responses. Results: Of 211 respondents, 103 (49%) report referring to PR < monthly or not at all. Identified enablers aligned with TDF domains on knowledge and skills. Most PHPs believed referral is easy (129; 61.1%) and (160; 75.9%) agreed to knowing PR programme content. Major barriers related to optimism (only 49 (23.6%) consider patients motivated) and (93; 44.1% believed patients in work are unable to attend). Barriers were also evident in domains social influences (44; 21.1%), report providers rarely engage & goals, (40; 18.9%) PHPs report in-practice measures to improve referral rates are rare. Conclusion: PR referral is infrequent. Knowledge and skills are evident, but interventions to overcome barriers; PHP perceptions of patient, provider engagement and improve goal focus are needed