1,882 research outputs found
Nucleation in sheared granular matter
We present an experiment on crystallization of packings of macroscopic
granular spheres. This system is often considered to be a model for thermally
driven atomic or colloidal systems. Cyclically shearing a packing of frictional
spheres, we observe a first order phase transition from a disordered to an
ordered state. The ordered state consists of crystallites of mixed FCC and HCP
symmetry that coexist with the amorphous bulk. The transition, initiated by
homogeneous nucleation, overcomes a barrier at 64.5% volume fraction.
Nucleation consists predominantly of the dissolving of small nuclei and the
growth of nuclei that have reached a critical size of about ten spheres
The Right to Development as a Mechanism for Group Autonomy: Protection of Tibetan Cultural Rights
Traditional legal mechanisms have failed to protect minority cultural integrity rights for the Tibetan people. Modem human rights law, however, offers a mechanism to protect cultural integrity through group autonomy. This Comment argues that the right to development can protect Tibetan cultural rights through such a claim for group autonomy over development
Maternal caregivers have confluence of altered cortisol, high reward-driven eating, and worse metabolic health.
Animal models have shown that chronic stress increases cortisol, which contributes to overeating of highly palatable food, increased abdominal fat and lower cortisol reactivity. Few studies in humans have simultaneously examined these trajectories. We examined premenopausal women, either mothers of children with a diagnosis of an autism spectrum disorder (n = 92) or mothers of neurotypical children (n = 91). At baseline and 2-years, we assessed hair cortisol, metabolic health, and reward-based eating. We compared groups cross-sectionally and prospectively, accounting for BMI change. Caregivers, relative to controls, had lower cumulative hair cortisol at each time point, with no decreases over time. Caregivers also had stable levels of poor metabolic functioning and greater reward-based eating across both time points, and evidenced increased abdominal fat prospectively (all ps â€.05), independent of change in BMI. This pattern of findings suggest that individuals under chronic stress, such as caregivers, would benefit from tailored interventions focusing on better regulation of stress and eating in tandem to prevent early onset of metabolic disease, regardless of weight status
Modelling quasicrystals at positive temperature
We consider a two-dimensional lattice model of equilibrium statistical
mechanics, using nearest neighbor interactions based on the matching conditions
for an aperiodic set of 16 Wang tiles. This model has uncountably many ground
state configurations, all of which are nonperiodic. The question addressed in
this paper is whether nonperiodicity persists at low but positive temperature.
We present arguments, mostly numerical, that this is indeed the case. In
particular, we define an appropriate order parameter, prove that it is
identically zero at high temperatures, and show by Monte Carlo simulation that
it is nonzero at low temperatures
Parapsychology and Transpersonal Psychology in Dialogue: Could These Two Movements Be Brought into Better Alignment?
Parapsychology and transpersonal psychology were founded independently and have evolved separately as two distinct movements, although there is considerable overlap in both their content and in the interests of a number of scholars who are active in both areas. Harris Friedman, Co-President of the Association of Transpersonal Psychology, and Dean Radin, President of the Parapsychological Association, engaged in an informal discussion on the salient commonalities and differences between the two movements, focusing on exploring ways that the two could be brought into better alignment, such as including more transpersonal approaches within parapsychological studies and vice versa. Stanley Krippner, whose seminal work straddles both areas, chaired the panel, introducing and serving as a discussant for Friedmanâs and Radinâs views, as well as in presenting his own views on the relationship between parapsychology and transpersonal psychology
Tiling Spaces are Inverse Limits
Let M be an arbitrary Riemannian homogeneous space, and let Omega be a space
of tilings of M, with finite local complexity (relative to some symmetry group
Gamma) and closed in the natural topology. Then Omega is the inverse limit of a
sequence of compact finite-dimensional branched manifolds. The branched
manifolds are (finite) unions of cells, constructed from the tiles themselves
and the group Gamma. This result extends previous results of Anderson and
Putnam, of Ormes, Radin and Sadun, of Bellissard, Benedetti and Gambaudo, and
of G\"ahler. In particular, the construction in this paper is a natural
generalization of G\"ahler's.Comment: Latex, 6 pages, including one embedded figur
Phase transition in a static granular system
We find that a column of glass beads exhibits a well-defined transition
between two phases that differ in their resistance to shear. Pulses of
fluidization are used to prepare static states with well-defined particle
volume fractions in the range 0.57-0.63. The resistance to shear is
determined by slowly inserting a rod into the column of beads. The transition
occurs at for a range of speeds of the rod.Comment: 4 pages, 4 figures. The paper is significantly extended, including
new dat
Drag Reduction In Solidâfluid Systems
Pressure drop measurements were made on a variety of dilute solidâliquid suspension systems in order to study the effects of particle shape and size, concentration, fluid viscosity, and tube diameter on friction factor. The central objective was to determine under what conditions drag reduction would occur. Copyright © 1975 American Institute of Chemical Engineer
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