Structure and dynamics of the interface between a binary hard-sphere crystal of NaCl type and its coexisting binary fluid

Molecular dynamics simulations are performed to study the [100] and [111] orientations of the crystal-melt interface between an ordered two-component hard sphere with a NaCl structure and its coexisting binary hard-sphere fluid. The diameter ratio of the two types of hard spheres making up the mixture is taken to be 0.414. This work complements our earlier interface simulations [J. Chem. Phys.116, 3410] for the same diameter ratio at lower pressures where the smaller component is immiscible in the solid and the fluid mixture coexists with a pure FCC crystal of large particles. Density profiles and diffusion coefficient profiles are presented for the AB interfacial system. We find that for this system, the transition from crystal-like to fluid-like behavior of both the density and diffusion constant profiles occurs over a narrower region than that seen in our previous studies [J. Chem. Phys. 116, 3410] of the FCC/binary fluid system. But similar to what was found in the FCC/binary fluid interface the transition region for the large particle diffusion constant is shifted about the size of the large particles toward the fluid phase relative to that for the small particles.Comment: 8 page

Photometric and spectroscopic evolution of the interacting transient at 2016jbu(Gaia16cfr)

We present the results from a high-cadence, multiwavelength observation campaign of AT 2016jbu (aka Gaia16cfr), an interacting transient. This data set complements the current literature by adding higher cadence as well as extended coverage of the light-curve evolution and late-time spectroscopic evolution. Photometric coverage reveals that AT 2016jbu underwent significant photometric variability followed by two luminous events, the latter of which reached an absolute magnitude of MV ∼-18.5 mag. This is similar to the transient SN 2009ip whose nature is still debated. Spectra are dominated by narrow emission lines and show a blue continuum during the peak of the second event. AT 2016jbu shows signatures of a complex, non-homogeneous circumstellar material (CSM). We see slowly evolving asymmetric hydrogen line profiles, with velocities of 500 km s-1 seen in narrow emission features from a slow-moving CSM, and up to 10 000 km s-1 seen in broad absorption from some high-velocity material. Late-time spectra (∼+1 yr) show a lack of forbidden emission lines expected from a core-collapse supernova and are dominated by strong emission from H, He i, and Ca ii. Strong asymmetric emission features, a bumpy light curve, and continually evolving spectra suggest an inhibit nebular phase. We compare the evolution of H α among SN 2009ip-like transients and find possible evidence for orientation angle effects. The light-curve evolution of AT 2016jbu suggests similar, but not identical, circumstellar environments to other SN 2009ip-like transients

Progenitor, environment, and modelling of the interacting transient AT 2016jbu (Gaia16cfr)

We present the bolometric light curve, identification and analysis of the progenitor candidate, and preliminary modelling of AT 2016jbu (Gaia16cfr). We find a progenitor consistent with a ∼22-25 M⊙ yellow hypergiant surrounded by a dusty circumstellar shell, in agreement with what has been previously reported. We see evidence for significant photometric variability in the progenitor, as well as strong Hα emission consistent with pre-existing circumstellar material. The age of the environment, as well as the resolved stellar population surrounding AT 2016jbu, supports a progenitor age of >10 Myr, consistent with a progenitor mass of ∼22 M⊙. A joint analysis of the velocity evolution of AT 2016jbu and the photospheric radius inferred from the bolometric light curve shows the transient is consistent with two successive outbursts/explosions. The first outburst ejected material with velocity ∼650 km s-1, while the second, more energetic event ejected material at ∼4500 km s-1. Whether the latter is the core collapse of the progenitor remains uncertain. We place a limit on the ejected 56Ni mass of <0.016 M⊙. Using the Binary Population And Spectral Synthesis (BPASS) code, we explore a wide range of possible progenitor systems and find that the majority of these are in binaries, some of which are undergoing mass transfer or common-envelope evolution immediately prior to explosion. Finally, we use the SuperNova Explosion Code (SNEC) to demonstrate that the low-energy explosions within some of these binary systems, together with sufficient circumstellar material, can reproduce the overall morphology of the light curve of AT 2016jbu

Computer simulation of colloidal suspensions

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A computer simulation investigation into the stability of the AB2 superlattice in a binary hard sphere system

The thermodynamic stability of the binary hard-sphere AB2 superlattice structure has been confirmed by means of computer simulations. This is consistent with the results of experimental studies of suspensions of hard-sphere colloidal particles. A fit of the Helmholtz free energy surface for the region in phase space where AB2 is found to be stable is presented, together with results for the c/a ratio of this hexagonal crystal

The stability of the AB13 crystal in a binary hard sphere system

A numerical study of the stability of the AB13 crystal structure in a mixture of dissimilar hard spheres is reported. This crystal structure has recently been observed by Bartlett and coworkers in experiments on suspensions of colloidal hard-sphere mixtures. We find that, over a range of densities and diameter ratios, the AB13 phase is thermodynamically stable both with respect to the fluid mixture and the crystal structures of pure A and pure B. A tentative phase diagram is presented

Working Paper Series Working Paper Series Working Paper Series Work In Progress What Changes in Therapy? Who Changes? Ordering Information What Changes in Therapy? Who Changes?

Relational-Cultural Model of psychological development, which grew out of a collaborative theory-building process led by Jean Baker Miller and her colleagues. The Institute offers workshops, courses, professional trainings, publications, and ongoing projects which explore applications of the relational-cultural approach. At the heart of this work is the belief that the Relational-Cultural model offers new and better ways of understanding the diversity and complexities of human experience. For more information, please visit: www.jbmti.org. The Wellesley Centers for Women Since 1974, the Wellesley Centers for Women has been a driving force, both behind the scenes and in the spotlight, promoting positive change for women and families. All work is grounded in the perspectives of women from diverse backgrounds. Our research and action projects lead to creative solutions and innovative policy alternatives to a range of pressing social concerns