Lamellae Stability in Confined Systems with Gravity

The microphase separation of a diblock copolymer melt confined by hard walls and in the presence of a gravitational field is simulated by means of a cell dynamical system model. It is found that the presence of hard walls normal to the gravitational field are key ingredients to the formation of well ordered lamellae in BCP melts. To this effect the currents in the directions normal and parallel to the field are calculated along the interface of a lamellar domain, showing that the formation of lamellae parallel to the hard boundaries and normal to the field correspond to the stable configuration. Also, it is found thet the field increases the interface width.Comment: 4 pages, 2 figures, submitted to Physical Review

A study of the effectiveness of telepsychiatry-based culturally sensitive collaborative treatment of depressed Chinese Americans

<p>Abstract</p> <p>Background</p> <p>Chinese American patients with Major Depressive Disorder (MDD) tend to underutilize mental health services and are more likely to seek help in primary care settings than from mental health specialists. Our team has reported that Culturally Sensitive Collaborative Treatment (CSCT) is effective in improving recognition and treatment engagement of depressed Chinese Americans in primary care. The current study builds on this prior research by incorporating telemedicine technology into the CSCT model.</p> <p>Methods/Design</p> <p>We propose a randomized controlled trial to evaluate the acceptability and effectiveness of a telepsychiatry-based culturally sensitive collaborative treatment (T-CSCT) intervention targeted toward Chinese Americans. Patients meeting the study's eligibility criteria will receive either treatment as usual or the intervention under investigation. The six-month intervention involves: 1) an initial psychiatric interview using a culturally sensitive protocol via videoconference; 2) eight scheduled phone visits with a care manager assigned to the patient, who will monitor the patient's progress, as well as medication side effects and dosage if applicable; and 3) collaboration between the patient's PCP, psychiatrist, and care manager. Outcome measures include depressive symptom severity as well as patient and PCP satisfaction with the telepsychiatry-based care management service.</p> <p>Discussion</p> <p>The study investigates the T-CSCT model, which we believe will increase the feasibility and practicality of the CSCT model by adopting telemedicine technology. We anticipate that this model will expand access to culturally competent psychiatrists fluent in patients' native languages to improve treatment of depressed minority patients in primary care settings.</p> <p>Trial Registration</p> <p><a href="http://www.clinicaltrials.gov/ct2/show/NCT00854542">NCT00854542</a></p

Macrorealism from entropic Leggett-Garg inequalities

We formulate entropic Leggett-Garg inequalities, which place constraints on the statistical outcomes of temporal correlations of observables. The information theoretic inequalities are satisfied if macrorealism holds. We show that the quantum statistics underlying correlations between time-separated spin component of a quantum rotor mimics that of spin correlations in two spatially separated spin-$s$ particles sharing a state of zero total spin. This brings forth the violation of the entropic Leggett-Garg inequality by a rotating quantum spin-$s$ system in similar manner as does the entropic Bell inequality (Phys. Rev. Lett. 61, 662 (1988)) by a pair of spin-$s$ particles forming a composite spin singlet state.Comment: 5 pages, RevTeX, 2 eps figures, Accepted for publication in Phys. Rev.

Observing two dark accelerators around the Galactic Centre with Fermi Large Area Telescope

We report the results from a detailed $\gamma-$ray investigation in the field of two "dark accelerators", HESS J1745-303 and HESS J1741-302, with $6.9$ years of data obtained by the Fermi Large Area Telescope. For HESS J1745-303, we found that its MeV-GeV emission is mainly originated from the "Region A" of the TeV feature. Its $\gamma-$ray spectrum can be modeled with a single power-law with a photon index of $\Gamma\sim2.5$ from few hundreds MeV to TeV. Moreover, an elongated feature, which extends from "Region A" toward northwest for $\sim1.3^{\circ}$, is discovered for the first time. The orientation of this feature is similar to that of a large scale atomic/molecular gas distribution. For HESS J1741-302, our analysis does not yield any MeV-GeV counterpart for this unidentified TeV source. On the other hand, we have detected a new point source, Fermi J1740.1-3013, serendipitously. Its spectrum is apparently curved which resembles that of a $\gamma-$ray pulsar. This makes it possibly associated with PSR B1737-20 or PSR J1739-3023.Comment: 11 pages, 7 figures, 2 tables, accepted for publication in MNRA

Phase Separation Kinetics in a Model with Order-Parameter Dependent Mobility

We present extensive results from 2-dimensional simulations of phase separation kinetics in a model with order-parameter dependent mobility. We find that the time-dependent structure factor exhibits dynamical scaling and the scaling function is numerically indistinguishable from that for the Cahn-Hilliard (CH) equation, even in the limit where surface diffusion is the mechanism for domain growth. This supports the view that the scaling form of the structure factor is "universal" and leads us to question the conventional wisdom that an accurate representation of the scaled structure factor for the CH equation can only be obtained from a theory which correctly models bulk diffusion.Comment: To appear in PRE, figures available on reques

Optimal Location of Sources in Transportation Networks

We consider the problem of optimizing the locations of source nodes in transportation networks. A reduction of the fraction of surplus nodes induces a glassy transition. In contrast to most constraint satisfaction problems involving discrete variables, our problem involves continuous variables which lead to cavity fields in the form of functions. The one-step replica symmetry breaking (1RSB) solution involves solving a stable distribution of functionals, which is in general infeasible. In this paper, we obtain small closed sets of functional cavity fields and demonstrate how functional recursions are converted to simple recursions of probabilities, which make the 1RSB solution feasible. The physical results in the replica symmetric (RS) and the 1RSB frameworks are thus derived and the stability of the RS and 1RSB solutions are examined.Comment: 38 pages, 18 figure

Spinodal Decomposition and the Tomita Sum Rule

The scaling properties of a phase-ordering system with a conserved order parameter are studied. The theory developed leads to scaling functions satisfying certain general properties including the Tomita sum rule. The theory also gives good agreement with numerical results for the order parameter scaling function in three dimensions. The values of the associated nonequilibrium decay exponents are given by the known lower bounds.Comment: 15 pages, 6 figure

Phase-ordering of conserved vectorial systems with field-dependent mobility

The dynamics of phase-separation in conserved systems with an O(N) continuous symmetry is investigated in the presence of an order parameter dependent mobility M(\phi)=1-a \phi^2. The model is studied analytically in the framework of the large-N approximation and by numerical simulations of the N=2, N=3 and N=4 cases in d=2, for both critical and off-critical quenches. We show the existence of a new universality class for a=1 characterized by a growth law of the typical length L(t) ~ t^{1/z} with dynamical exponent z=6 as opposed to the usual value z=4 which is recovered for a<1.Comment: RevTeX, 8 pages, 13 figures, to be published in Phys. Rev.

Two-scale competition in phase separation with shear

The behavior of a phase separating binary mixture in uniform shear flow is investigated by numerical simulations and in a renormalization group (RG) approach. Results show the simultaneous existence of domains of two characteristic scales. Stretching and cooperative ruptures of the network produce a rich interplay where the recurrent prevalence of thick and thin domains determines log-time periodic oscillations. A power law growth $R(t) \sim t^{\alpha}$ of the average domain size, with $\alpha =4/3$ and $\alpha = 1/3$ in the flow and shear direction respectively, is shown to be obeyed.Comment: 5 Revtex pages, 4 figure

Stability of a Nonequilibrium Interface in a Driven Phase Segregating System

We investigate the dynamics of a nonequilibrium interface between coexisting phases in a system described by a Cahn-Hilliard equation with an additional driving term. By means of a matched asymptotic expansion we derive equations for the interface motion. A linear stability analysis of these equations results in a condition for the stability of a flat interface. We find that the stability properties of a flat interface depend on the structure of the driving term in the original equation.Comment: 14 pages Latex, 1 postscript-figur