Tunable intracellular transport on converging microtubule morphologies.

A common type of cytoskeletal morphology involves multiple microtubules converging with their minus ends at the microtubule organizing center (MTOC). The cargo-motor complex will experience ballistic transport when bound to microtubules or diffusive transport when unbound. This machinery allows for sequestering and subsequent dispersal of dynein-transported cargo.

Swarmalators with delayed interactions.

We investigate the effects of delayed interactions in a population of "swarmalators," generalizations of phase oscillators that both synchronize in time and swarm through space. We discover two steady collective states: a state in which swarmalators are essentially motionless in a disk arranged in a pseudocrystalline order, and a boiling state in which the swarmalators again form a disk, but now the swarmalators near the boundary perform boiling-like convective motions. These states are reminiscent of the beating clusters seen in photoactivated colloids and the living crystals of starfish embryos.

Fisher-Kolmogorov-Petrovsky-Piskunov dynamics mediated by a parent field with a delay.

We examine a modification of the Fisher-Kolmogorov-Petrovsky-Piskunov (FKPP) process in which the diffusing substance requires a parent density field for reproduction. A biological example would be the density of diffusing spores (propagules) and the density of a stationary fungus (parent). The parent produces propagules at a certain rate, and the propagules turn into the parent substance at another rate.

Fragility of reaction-diffusion models with respect to competing advective processes.

We study the coupling of a Fisher-Kolmogorov-Petrovsky-Piskunov (FKPP) equation to a separate, advection-only transport process. We find that an infinitesimal coupling can cause a finite change in the speed and shape of the reaction front, indicating the fragility of the FKPP model with respect to such a perturbation. The front dynamics can be mapped to an effective FKPP equation only at sufficiently fast diffusion or large coupling strength.

Two-strain competition in quasineutral stochastic disease dynamics.

We develop a perturbation method for studying quasineutral competition in a broad class of stochastic competition models and apply it to the analysis of fixation of competing strains in two epidemic models. The first model is a two-strain generalization of the stochastic susceptible-infected-susceptible (SIS) model. Here we extend previous results due to Parsons and Quince [Theor.

Universality in the one-dimensional chain of phase-coupled oscillators.

We apply a recently developed renormalization-group (RG) method to study synchronization in a one-dimensional chain of phase-coupled oscillators in the regime of weak randomness. The RG predicts how oscillators with randomly distributed frequencies and couplings form frequency-synchronized clusters. Although the RG was originally intended for strong randomness, i.

Renormalization group approach to oscillator synchronization.

We develop a renormalization group method to investigate synchronization clusters in a one-dimensional chain of nearest-neighbor coupled phase oscillators. The method is best suited for chains with strong disorder in the intrinsic frequencies and coupling strengths. The results are compared with numerical simulations of the chain dynamics and good agreement in several characteristics is found.

Basins of attraction of a nonlinear nanomechanical resonator.

We present an experiment that systematically probes the basins of attraction of two fixed points of a nonlinear nanomechanical resonator and maps them out with high resolution. We observe a separatrix which progressively alters shape for varying drive strength and changes the relative areas of the two basins of attraction. The observed separatrix is blurred due to ambient fluctuations, including residual noise in the drive system, which cause uncertainty in the preparation of an initial state close to the separatrix.

Controlling transitions in a Duffing oscillator by sweeping parameters in time.

We consider a high-Q Duffing oscillator in a weakly nonlinear regime with the driving frequency sigma varying in time between sigma i and sigma f at a characteristic rate r. We found that the frequency sweep can cause controlled transitions between two stable states of the system. Moreover, these transitions are accomplished via a transient that lingers for a long time around the third, unstable fixed point of saddle type.

A comparison of anti-desmoglein antibodies and indirect immunofluorescence in the serodiagnosis of pemphigus vulgaris.

Background: Indirect immunofluorescence (IIF) is the standard method for the detection of pemphigus autoantibodies. Commercially available enzyme-linked immunosorbent assays (ELISAs) have recently become available to measure serum antibodies (Abs) against desmoglein1 (Dsg1) and desmoglein3 (Dsg3). It has been suggested that patients with mucosal-dominant pemphigus vulgaris (PV) have serum Abs against Dsg3 only, patients with mucocutaneous PV have Abs to both Dsg1 and Dsg3, and patients with pemphigus foliaceus (PF) have Abs against Dsg1 only.

Preliminary crystallographic study of turkey gizzard vinculin.

Vinculin is a 117 kDa microfilament-associated protein located at the cytoplasmic aspects of focal contacts and cell-cell adherens type junctions. In both sites, vinculin participates in the formation of a submembrane 'plaque' structure which is responsible for the attachment of actin filaments to the plasma membrane. Vinculin consists of 1066 amino acids, which form a large 90 kDa globular head domain and a rod-like 29 kDa tail domain.

Immediate versus delayed treatment of perimenopausal bleeding due to benign causes by balloon thermal ablation.

Study Objective: To compare the effectiveness and safety of thermal balloon ablation without pretreatment with endometrium-thinning agents compared with delayed ablation with pretreatment for women with perimenopausal menorrhagia.

Design: Prospective, randomized, controlled trial (Canadian Task Force classification I).

Setting: Hospital-based ambulatory medical center.

Vaginal ultrasonography in patients with postmenopausal bleeding.

Our objective was to define a subset of women with postmenopausal bleeding in whom the accepted practice of endometrial sampling could be safely omitted. Vaginal endosonographic measurements were compared to the histological findings of curettings following diagnostic dilatation and curettage in 129 women with post-menopausal bleeding who were not receiving hormonal therapy. Atrophy was diagnosed in 49%, slight proliferation in 10%, endometrial polyps in 11%, hypoplasia in 12%, and adenocarcinoma in 12%.

Gradual cervical dilation for termination of early second-trimester pregnancy with a double balloon device.

Thirty-two women with pregnancies of 12-15 weeks underwent cervical dilation before abortion using a double balloon device. In all cases, satisfactory dilation was achieved and evacuation accomplished. The slow dilation process, resulting from the continuous indirect dilator effect of the balloons, was not associated with patient inconvenience in most cases.