The Effects of Weak Spatiotemporal Noise on a Bistable One-Dimensional System

We treat analytically a model that captures several features of the phenomenon of spatially inhomogeneous reversal of an order parameter. The model is a classical Ginzburg-Landau field theory restricted to a bounded one-dimensional spatial domain, perturbed by weak spatiotemporal noise having a flat power spectrum in time and space. Our analysis extends the Kramers theory of noise-induced transitions to the case when the system acted on by the noise has nonzero spatial extent, and the noise itself is spatially dependent. By extending the Langer-Coleman theory of the noise-induced decay of a metastable state, we determine the dependence of the activation barrier and the Kramers reversal rate prefactor on the size of the spatial domain. As this is increased from zero and passes through a certain critical value, a transition between activation regimes occurs, at which the rate prefactor diverges. Beyond the transition, reversal preferentially takes place in a spatially inhomogeneous rather than in a homogeneous way. Transitions of this sort were not discovered by Langer or Coleman, since they treated only the infinite-volume limit. Our analysis uses higher transcendental functions to handle the case of finite volume. Similar transitions between activation regimes should occur in other models of metastable systems with nonzero spatial extent, perturbed by weak noise, as the size of the spatial domain is varied.Comment: 16 page

Lowell Park: Reconnecting a City to Its Waterfront

Stillwater lies in one of the most beautiful locations in Minnesota. It harbors a rich history linked to the river and was one of the first settlements in Minnesota. As of late Stillwater?s downtown has been a hot spot for tourists and travelers. Located only 18 miles from the Twin Cities it attracts many people to this beautiful location. By creating an adjacent waterfront that compliments the already beautiful and successful downtown it will encourage more use and user circulation throughout more of the city. The focus of this design will essentially be to complete Stillwater?s overall downtown by re-designing and connecting it to its waterfront. Stillwater?s downtown currently seems unfinished because the potential of the urban waterfront is untapped. This design will create another focal point for the city center, and utilize the huge potential of its urban waterfront

Asymptotic Exit Location Distributions in the Stochastic Exit Problem

Consider a two-dimensional continuous-time dynamical system, with an attracting fixed point $S$. If the deterministic dynamics are perturbed by white noise (random perturbations) of strength $\epsilon$, the system state will eventually leave the domain of attraction $\Omega$ of $S$. We analyse the case when, as $\epsilon\to0$, the exit location on the boundary $\partial\Omega$ is increasingly concentrated near a saddle point $H$ of the deterministic dynamics. We show that the asymptotic form of the exit location distribution on $\partial\Omega$ is generically non-Gaussian and asymmetric, and classify the possible limiting distributions. A key role is played by a parameter $\mu$, equal to the ratio $|\lambda_s(H)|/\lambda_u(H)$ of the stable and unstable eigenvalues of the linearized deterministic flow at $H$. If $\mu<1$ then the exit location distribution is generically asymptotic as $\epsilon\to0$ to a Weibull distribution with shape parameter $2/\mu$, on the $O(\epsilon^{\mu/2})$ length scale near $H$. If $\mu>1$ it is generically asymptotic to a distribution on the $O(\epsilon^{1/2})$ length scale, whose moments we compute. The asymmetry of the asymptotic exit location distribution is attributable to the generic presence of a `classically forbidden' region: a wedge-shaped subset of $\Omega$ with $H$ as vertex, which is reached from $S$, in the $\epsilon\to0$ limit, only via `bent' (non-smooth) fluctuational paths that first pass through the vicinity of $H$. We deduce from the presence of this forbidden region that the classical Eyring formula for the small-$\epsilon$ exponential asymptotics of the mean first exit time is generically inapplicable.Comment: This is a 72-page Postscript file, about 600K in length. Hardcopy requests to [email protected] or [email protected]

Predation by Pellet-Reared Tiger Muskellunge on Minnows and Bluegills in Experimental Systems

Studies in Wisconsin lakes have shown that stocked tiger muskellunge( F1 hybrids of female muskellunge, Esox masquinongy * male northern pike, E.lucius) reared on live food survive better than those reared entirely on dry pellet food. We evaluated the ability of pellet-reared hybrids to convert to a minnow(Notropis spp. and Pimephales promelas) or bluegill (Lepomis macrochirus) diet in laboratory aquaria and hatchery ponds. In aquaria, 86-310-mm (total length) tiger muskellunge selected cyprinids that were about 40% of their own length and bluegills that were about 30% of their length, sizes closely predicted by an optimal foraging construct (time from prey capture to complete prey ingestion / prey dry weight). Using these prey sizes, we tested hybrids (130, 150, and 170mm long) in conversion experiments in aquaria and ponds. During experiments, prey were maintained at a constant density and predators were sampled periodically to determine the proportion eating fish. Tiger muskellunge converted more slowly to bluegills than to minnows in both aquaria and ponds. In aquaria, 85% of the hybrids converted from pellets to minnows by day 3, whereas only 68% converted to bluegills. By day 5, conversions to minnows and bluegills were 95% and 82%, respectively. In ponds, 73% of the hybrids converted to minnows by day 5 and 89% by day 14. No hybrids had eaten bluegills by day 3 and only 53% converted by day 14. The apparently limited ability of pellet-reared tiger muskellunge to switch to a bluegill diet may influence survival and growth of these predators in reservoirs dominated by a centrachid forage base.This research was supported in part by funds from the Federal Aid in Fish Restoration Act under Dingell-Johnson Project F-57-R

34587 Efficacy of ruxolitinib cream for the treatment of atopic dermatitis by anatomic region: Pooled analysis from two randomized phase 3 studies

Atopic dermatitis (AD) is a highly pruritic inflammatory skin disease. Two phase 3 studies (TRuE-AD1/TRuE-AD2) enrolled patients aged ≥12 years with AD for ≥2 years, an Investigator’s Global Assessment (IGA) score of 2/3, and 3%–20% affected body surface area. Patients (total N = 1249; median age, 32 years) were randomized (2:2:1) to twice-daily 0.75% ruxolitinib (Janus kinase [JAK] 1/JAK2 inhibitor) cream, 1.5% ruxolitinib cream, or vehicle cream for 8 weeks of double-blind treatment, and thereafter continued in a long-term, 44-week period of the studies. In this pooled analysis, mean percentage change from baseline in Eczema Area and Severity Index (EASI) anatomic region subscores is reported up to Week 8 (n = 1208). For the head and neck region, patients applying 0.75%/1.5% ruxolitinib cream (vs vehicle) achieved mean improvements of 59.3%/55.8% (vs 13.4%), 70.4%/71.3% (vs 22.4%), and 70.0%/78.7% (vs 45.0%) at Weeks 2, 4, and 8, respectively (all P \u3c.0001). Results were similar for the upper limbs region (48.5%/54.7% [vs 13.3%], 66.6%/70.3% [vs 25.0%], and 73.5%/74.9% [vs 35.1%] all P \u3c.0001). For the trunk region, patients achieved mean improvements of 49.8%/60.0% (vs 12.1%), 67.3%/73.8% (vs 15.0%), and 72.7%/81.0% (vs 15.6%) at Weeks 2, 4, and 8, respectively (all P \u3c.0001). Similar results were observed for the lower limbs region (46.0%/48.2% [vs 16.3%], 65.9%/66.2% [vs 13.9%], and 76.3%/74.9% [vs 39.8%]; all P \u3c.0001). Ruxolitinib cream was well tolerated, with an adverse event profile similar to vehicle. In summary, ruxolitinib cream demonstrated significant improvements vs vehicle in patients with AD across anatomic regions as early as Week 2

Pore space and brittle damage evolution in concrete

AbstractA novel lattice model is proposed for linking experimentally measured porosity of concrete to damage evolution and the emergent macroscopic behaviour. Pore sizes are resolved by X-ray CT and distributed at lattice bonds. The mechanical behaviour of bonds is elastic-brittle with failure criterion dependent on local forces and pore sizes. Bond failures provide the only non-linear effect on the macroscopic response. Results are compared to several experimental load cases. They show good agreement of stress–strain response at lower stress levels and expected differences at peak stresses. The framework allows for future development of models with plasticity and time-dependent effects

Vitiligo-like manifestations of graft-versus-host disease in a pediatric population

Vitiligo-like changes are an uncommon cutaneous manifestation of graft-versus-host disease (GVHD). We report three cases and review the literature of pediatric patients with vitiligo-like changes associated with GVHD. Improved characterization of this phenomenon may lend insight into the biologic pathways that underlie both vitiligo and GVHD

Expression of cell cycle regulatory factors in differentiating osteoblasts: postproliferative up-regulation of cyclins B and E

The representation of cyclins and cyclin-dependent kinases (cdks) was analyzed during progressive development of the bone cell phenotype in cultures of normal diploid rat calvarial osteoblasts. Three developmental stages were examined: (a) proliferation; (b) monolayer confluency; and (c) mineralization of the bone extracellular matrix. We demonstrate that the presence of cyclins and cdks is not restricted to the proliferation period. Consistent with their role in cell cycle progression, cdc2 and cdk2 decrease postproliferatively. However, cdk4 and cyclins A, B, and D1 persist in confluent cells. Cyclin E is significantly up-regulated during the extracellular matrix mineralization developmental period. Examination of the cytoplasmic levels of these cell cycle regulatory proteins indicates a marked increase in cyclin B in the late differentiation stage. The elevation of nuclear cyclin E and cytoplasmic cyclin B is not observed in osteoblasts maintained under culture conditions that do not support differentiation. Furthermore, treatment with transforming growth factor beta for 48 h during the proliferation period renders the cells incompetent for differentiation and abrogates the postproliferative up-regulation of cyclins B and E. Density-induced growth inhibition of ROS 17/2.8 osteosarcoma cells is not accompanied by up-regulation of nuclear cyclin E and cytoplasmic cyclin B when compared to the proliferation period. This observation is consistent with abrogation of both growth control and differentiation regulatory mechanisms in tumor cells. These results suggest that cell cycle regulatory proteins function not only during proliferation but may also play a role in normal diploid osteoblast differentiation

Management Issues and Their Relative Priority within State Fisheries Agencies

For researchers and managers to work together for greatest mutual benefit, researchers must understand what issues fisheries managers consider most important. To assess management priorities, we conducted a mail survey asking U.S. state fisheries agencies to identify the priority, based on personnel time, they place on 12 fisheries management issues. Based on an 88% response rate, we determined relative emphases across (1) management issues, (2) geographic regions, and (3) freshwater or marine orientations. Issues directly linked to sport and commercial fishers, i.e., stocking, harvest regulations, fishing pressure, and exploring recruitment, were of paramount importance in all agency time budgets. The issue that included conflict, policy, and human dimensions concerns also was identified as "high priority." Six other issueshabitat restoration, hydropower licensing, instream flow, contaminants, introduced species, and nongame species-were of "moderate priority" nationwide. Approximately 50% of the issues varied in emphases across geographic region, and five issues were differentially emphasized in agencies with freshwater and marine responsibilities. To solve persistent problems that plague fisheries management, agencies must clearly identify high-priority management concerns and communicate their specific problem-solving needs to researchers. Results of this survey should provide a first step in identifying these management priorities and research needs