Correlation between flexibility of chain-like polyelectrolyte and thermodynamic properties of its solution

Structural and thermodynamic properties of the model solution containing charged oligomers and the equivalent number of counterions were studied by means of the canonical Monte Carlo simulation technique. The oligomers are represented as (flexible) freely jointed chains or as a linear (rigid) array of charged hard spheres. In accordance with the primitive model of electrolyte solutions, the counterions are modeled as charged hard spheres and the solvent as dielectric continuum. Significant differences in the pair distribution functions, obtained for the rigid (rod-like) and flexible model are found but the differences in thermodynamic properties, such as, enthalpy of dilution and excess chemical potential, are less significant. The results are discussed in light of the experimental data an aqueous polyelectrolyte solutions. The simulations suggest that deviations from the fully extended (rod-like) conformation yield slightly stronger binding of counterions. On the other hand, the flexibility of polyions, even when coupled with the ion-size effects, cannot be blamed for qualitative differences between the theoretical results and experimental data for enthalpy of dilution.Comment: 14 pages, 10 figure

Effects of translational and rotational degrees of freedom on the properties of model water

Molecular dynamics simulations with separate thermostats for rotational and translational motions were used to study the effects of these degrees of freedom on the structure of water at a fixed density. To describe water molecules, we used the SPC/E model. The results indicate that an increase of the rotational temperature, $T_\textrm{R}$, causes a significant breaking of the hydrogen bonds. This is not the case, at least not to such an extent, when the translational temperature, $T_\textrm{T}$, is raised. The probability of finding an empty spherical cavity (no water molecule present) of a given size, strongly decreases with an increase of $T_\textrm{R}$, but this only marginally affects the free energy of the hydrophobe insertion. The excess internal energy increases proportionally with an increase of $T_\textrm{R}$, while an increase of $T_\textrm{T}$ yields a much smaller effect at high temperatures. The diffusion coefficient of water exhibits a non-monotonous behaviour with an increase of the rotational temperature.Comment: 9 pages, 9 figure

Fluid of fused spheres as a model for protein solution

In this work we examine thermodynamics of fluid with "molecules" represented by two fused hard spheres, decorated by the attractive square-well sites. Interactions between these sites are of short-range and cause association between the fused-sphere particles. The model can be used to study the non-spherical (or dimerized) proteins in solution. Thermodynamic quantities of the system are calculated using a modification of Wertheim's thermodynamic perturbation theory and the results compared with new Monte Carlo simulations under isobaric-isothermal conditions. In particular, we are interested in the liquid-liquid phase separation in such systems. The model fluid serves to evaluate the effect of the shape of the molecules, changing from spherical to more elongated (two fused spheres) ones. The results indicate that the effect of the non-spherical shape is to reduce the critical density and temperature. This finding is consistent with experimental observations for the antibodies of non-spherical shape.Comment: 12 pages, 5 figure

The Risk-Taking Software Engineer: A Framed Portrait

Background: Risk-taking is prevalent in a host of activities performed by software engineers on a daily basis, yet there is scant research on it. Aims and Method: We study if software engineers' risk-taking is affected by framing effects and by software engineers' personality. To this end, we perform a survey experiment with 124 software engineers. Results: We find that framing substantially affects their risk-taking. None of the "Big Five" personality traits are related to risk-taking in software engineers after correcting for multiple testing. Conclusions: Software engineers and their managers must be aware of framing effects and account for them properly

Managers’ mental health during the pandemic – the good, the bad, and the ugly

The job of a manager is often stressful during normal times. But a pandemic changes everything. Lorenz Graf-Vlachy finds that one of the factors affecting manager’s mental health during the COVID-19 crisis is having to perform tasks that they feel they shouldn’t have to be doing. He discusses how organisations can help managers overcome their distress

Does the partisan divide extend to online reviews?

Liberals and conservatives differ starkly in their political convictions, and their assessment of social and economic issues. Surprisingly, they also write very different online reviews when they evaluate online purchases. Researchers analysed the web browsing behaviour of a sample of US consumers and found that liberal customers write online reviews that are longer and contain more arguments. Lorenz Graf-Vlachy explains the findings and examines the factors behind these behavioural differences

Primitive model electrolytes. A comparison of the HNC approximation for the activity coefficient with Monte Carlo data

Accuracy of the mean activity coefficient expression (Hansen-Vieillefosse-Belloni equation), valid within the hypernetted chain (HNC) approximation, was tested in a wide concentration range against new Monte Carlo (MC) data for +1:-1 and +2:-2 primitive model electrolytes. The expression has an advantage that the excess chemical potential can be obtained directly, without invoking the time consuming Gibbs-Duhem calculation. We found the HNC results for the mean activity coefficient to be in good agreement with the machine calculations performed for the same model. In addition, the thermodynamic consistency of the HNC approximation was tested. The mean activity coefficients, calculated via the Gibbs-Duhem equation, seem to follow the MC data slightly better than the Hansen-Vieillefosse-Belloni expression. For completeness of the calculation, the HNC excess internal energies and osmotic coefficients are also presented. These results are compared with the calculations based on other theories commonly used to describe electrolyte solutions, such as the mean spherical approximation, Pitzer's extension of the Debye-H\"uckel theory, and the Debye-H\"uckel limiting law.Comment: 15 pages, 6 figure

SOCIAL INFLUENCE IN TECHNOLOGY ADOPTION RESEARCH: A LITERATURE REVIEW AND RESEARCH AGENDA

Social influence has been shown to profoundly affect human behavior in general and technology adoption (TA) in particular. Over time, multiple definitions and measures of social influence have been introduced to the field of TA research, contributing to an increasingly fragmented landscape of constructs that challenges the conceptual integrity of the field. In this vein, this paper sets out to review how social influence has been conceptualized with regard to TA. In so doing, this paper hopes to inform researchers’ understanding of the construct, provide an overview of its myriad conceptualizations, constructively challenge extant approaches, and provide impulses for future research. A systematic review of the relevant literature uncovers that extant interpretations of social influence are 1) predominantly compliance-based and as such risk overlooking identification- and internalization-based effects, and 2) primarily targeted at the individual level, thereby neglecting the impact of socially rich environments. Building upon these insights, this paper develops an integrated perspective on social influence in TA research that encourages scholars to pursue a multi-theoretical understanding of social influence at the interface of users, social referents, and technology