Accurate simulation estimates of cloud points of polydisperse fluids

We describe two distinct approaches to obtaining cloud point densities and coexistence properties of polydisperse fluid mixtures by Monte Carlo simulation within the grand canonical ensemble. The first method determines the chemical potential distribution $\mu(\sigma)$ (with $\sigma$ the polydisperse attribute) under the constraint that the ensemble average of the particle density distribution $\rho(\sigma)$ matches a prescribed parent form. Within the region of phase coexistence (delineated by the cloud curve) this leads to a distribution of the fluctuating overall particle density n, p(n), that necessarily has unequal peak weights in order to satisfy a generalized lever rule. A theoretical analysis shows that as a consequence, finite-size corrections to estimates of coexistence properties are power laws in the system size. The second method assigns $\mu(\sigma)$ such that an equal peak weight criterion is satisfied for p(n)$for all points within the coexistence region. However, since equal volumes of the coexisting phases cannot satisfy the lever rule for the prescribed parent, their relative contributions must be weighted appropriately when determining$\mu(\sigma)$. We show how to ascertain the requisite weight factor operationally. A theoretical analysis of the second method suggests that it leads to finite-size corrections to estimates of coexistence properties which are {\em exponentially small} in the system size. The scaling predictions for both methods are tested via Monte Carlo simulations of a novel polydisperse lattice gas model near its cloud curve, the results showing excellent quantitative agreement with the theory.Comment: 8 pages, 6 figure

In-vivo magnetic resonance imaging of hyperpolarized silicon particles

Silicon-based micro and nanoparticles have gained popularity in a wide range of biomedical applications due to their biocompatibility and biodegradability in-vivo, as well as a flexible surface chemistry, which allows drug loading, functionalization and targeting. Here we report direct in-vivo imaging of hyperpolarized 29Si nuclei in silicon microparticles by MRI. Natural physical properties of silicon provide surface electronic states for dynamic nuclear polarization (DNP), extremely long depolarization times, insensitivity to the in-vivo environment or particle tumbling, and surfaces favorable for functionalization. Potential applications to gastrointestinal, intravascular, and tumor perfusion imaging at sub-picomolar concentrations are presented. These results demonstrate a new background-free imaging modality applicable to a range of inexpensive, readily available, and biocompatible Si particles.Comment: Supplemental Material include

Senior Executives’ Basic Psychological Need Satisfaction and Psychological Well-being: Is It Different at the Top?

Senior executives’ decisions can have a substantial impact on their own lives, their families, their organizations’ workers and employees, and society. This quantitative study (1) investigated the relationship between basic psychological need satisfaction (BPNS) at work and psychological well-being (PWB) in 142 senior executives as antecedent of their decision making and (2) compared the results to two other managerial level samples of 260 managers and 445 employees. The results have implications for theory and practice. Our findings contribute the new theoretical perspectives of differences in the relationship between BPNS at work and PWB by managerial level and senior executives’ gender (“complementarity effect”). In turn, our research provides evidence for practical organizational applications such as the design and implementation of effective human resource development programs based on BPNS. Our findings further underscore the importance of senior executive psychology as a field of academic inquiry and provide directions for future research focused on further improving senior executives’ optimal functioning

Relatedness Need Satisfaction in Senior Executives

This research investigated relatedness need satisfaction in senior executives in three studies (two qualitative/ one quantitative). In study 1, we identified a matrix of coping strategies (MoCS) as conceptualization of senior executives’ behavioral responses to perceived social rejection or exclusion. Study 2 found that senior executives’ level of relatedness need satisfaction as a potential indicator of self-regulation failure was not significantly different from the rest of us. However, every sixth senior executive participant and every fourth senior executive participant from large organizations had a very low relatedness need satisfaction score with very large effect size. The final study 3, identified a relatedness loop model (RLM) as a theoretical framework for relatedness need satisfaction processes. In summary, our work offers an empirical foundation for future research as well as for practical tools and applications in the field of senior executive psychology

A single-domain spectral method for black hole puncture data

We calculate puncture initial data corresponding to both single and binary black hole solutions of the constraint equations by means of a pseudo-spectral method applied in a single spatial domain. Introducing appropriate coordinates, these methods exhibit rapid convergence of the conformal factor and lead to highly accurate solutions. As an application we investigate small mass ratios of binary black holes and compare these with the corresponding test mass limit that we obtain through a semi-analytical limiting procedure. In particular, we compare the binding energy of puncture data in this limit with that of a test particle in the Schwarzschild spacetime and find that it deviates by 50% from the Schwarzschild result at the innermost stable circular orbit of Schwarzschild, if the ADM mass at each puncture is used to define the local black hole masses.Comment: 13 pages, 6 figures; published version with one important change, see Fig. 4 and the corresponding changes to the tex

Continuous measurements in a composite quantum system and possible exchange of information between its parts

We study an influence of the continuous measurement in a composite quantum system C on the evolution of the states of its parts. It is shown that the character of the evolution (decoherence or recoherence) depends on the type of the measured quantity and on the initial state of the system. A number of conditions under which the states of the subsystems of C decohere during the measuring process are established. We propose a model of the composite system and specify the observable the measurement of which may result in the recoherence of the state of one of the subsystems of C. In the framework of this model we find the optimal regime for the exchange of information between the parts of C during the measurement. The main characteristics of such a process are computed. We propose a scheme of detection of the recoherence under the measurement in a concrete physical experiment.Comment: 6 page

Transport model analysis of particle correlations in relativistic heavy ion collisions at femtometer scales

The pion source as seen through HBT correlations at RHIC energies is investigated within the UrQMD approach. We find that the calculated transverse momentum, centrality, and system size dependence of the Pratt-HBT radii $R_L$ and $R_S$ are reasonably well in line with experimental data. The predicted $R_O$ values in central heavy ion collisions are larger as compared to experimental data. The corresponding quantity $\sqrt{R_O^{2}-R_S^{2}}$ of the pion emission source is somewhat larger than experimental estimates.Comment: 12 pages, 5 figures, to be published in PR