Slowly varying control parameters, delayed bifurcations and the stability of spikes in reaction-diffusion systems

We present three examples of delayed bifurcations for spike solutions of reaction-diffusion systems. The delay effect results as the system passes slowly from a stable to an unstable regime, and was previously analysed in the context of ODE's in [P.Mandel, T.Erneux, J.Stat.Phys, 1987]. It was found that the instability would not be fully realized until the system had entered well into the unstable regime. The bifurcation is said to have been "delayed" relative to the threshold value computed directly from a linear stability analysis. In contrast, we analyze the delay effect in systems of PDE's. In particular, for spike solutions of singularly perturbed generalized Gierer-Meinhardt (GM) and Gray-Scott (GS) models, we analyze three examples of delay resulting from slow passage into regimes of oscillatory and competition instability. In the first example, for the GM model on the infinite real line, we analyze the delay resulting from slowly tuning a control parameter through a Hopf bifurcation. In the second example, we consider a Hopf bifurcation on a finite one-dimensional domain. In this scenario, as opposed to the extrinsic tuning of a system parameter through a bifurcation value, we analyze the delay of a bifurcation triggered by slow intrinsic dynamics of the PDE system. In the third example, we consider competition instabilities of the GS model triggered by the extrinsic tuning of a feed rate parameter. In all cases, we find that the system must pass well into the unstable regime before the onset of instability is fully observed, indicating delay. We also find that delay has an important effect on the eventual dynamics of the system in the unstable regime. We give analytic predictions for the magnitude of the delays as obtained through analysis of certain explicitly solvable nonlocal eigenvalue problems. The theory is confirmed by numerical solutions of the full PDE systems.Comment: 31 pages, 20 figures, submitted to Physica D: Nonlinear Phenomen

Cloudtop

Even as users rely more on the web for their computing needs, they continue to depend on a desktop-like area for quick access to in-use resources. The traditional desktop is file-centric and prone to clutter, making it suboptimal for use in a web-dominated world. This paper introduces Cloudtop, a browser plugin that offers a lightweight workplace for temporary items, optimized around the idea that its contents originate from and will ultimately return to the web. Cloudtop improves upon the desktop by 1) implementing a simple, time-based notebook metaphor for managing clutter, 2) capturing and bundling extensible metadata for web resources, and 3) providing a platform for greater interface uniformity across sites

Clui: A Platform for Handles to Rich Objects

On the desktop, users are accustomed to having visible handles to objects that they want to organize, share, or manipulate. Web applications today feature many classes of such objects, like flight itineraries, products for sale, people, recipes, and businesses, but there are no interoperable handles for high-level semantic objects that users can grab. This paper proposes Clui, a platform for exploring a new data type, called a Webit, that provides uniform handles to rich objects. Clui uses plugins to 1) create Webits on existing pages by extracting semantic data from those pages, and 2) augmenting existing sites with drag and drop targets that accept and interpret Webits. Users drag and drop Webits between sites to transfer data, auto-fill search forms, map associated locations, or share Webits with others. Clui enables experimentation with handles to semantic objects and the standards that underlie them

Outcomes of a first point of contact speech language therapy clinic for patients requiring vocal cord check pre and post thyroid/parathyroid surgery

Introduction Speech Language Therapy First Point of Contact Clinic (SLT-FPOCC) models can assist assessment of low-risk patient populations referred to ear, nose and throat (ENT) services. To further improve ENT waitlist management and compliance with best-practice care, consideration of other low-risk populations that could be safely managed through this service model is needed. The aims of this paper are to evaluate the clinical and service outcomes of completing vocal cord check (VCC) assessments for patients’ pre and post thyroid/parathyroid surgery within an SLT-FPOCC model and examine consumer perceptions. Methods & Procedures The service followed existing SLT-FPOCC procedures, with ENT triaging referrals, then SLT completing pre- and postoperative VCC assessment (interview, perceptual assessment, flexible nasendoscopy), with assessment data later reviewed by ENT to diagnose laryngeal pathology. Clinical and service outcomes were collected prospectively. Patients completed an anonymous post-service satisfaction survey. Results Of the first 100 patients referred for preoperative VCCs, SLT assessment identified 42 with dysphonia and 30 reporting dysphagia, while ENT confirmed 9 with significant preoperative anatomical findings. Eighty-three underwent surgery, with 63 (95 nerves at surgical risk) returning for a postoperative VCC. Postoperative VCC identified three temporary neuropraxias (3.2%) and three unilateral vocal fold paresis (3.2%). Patients were highly satisfied with the service. All 163 pre-/postoperative VCCs were completed with no adverse events. Conclusion & Implications The current data support SLT-FPOCC service expansion to include pre and post thyroid/parathyroid surgery VCC checks, with positive consumer perception. The model supports delivery of best practice management (i.e., pre- and postoperative VCC) for patients receiving surgery for thyroid/parathyroid dysfunction, and associated efficiencies for ENT services

A multidimensional view of racial differences in access to prostate cancer care

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139082/1/cncr30894.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139082/2/cncr30894_am.pd

Piloting the Global Subsidy: The Impact of Subsidized Artemisinin-Based Combination Therapies Distributed through Private Drug Shops in Rural Tanzania

BACKGROUND: WHO estimates that only 3% of fever patients use recommended artemisinin-based combination therapies (ACTs), partly reflecting their high prices in the retail sector from where many patients seek treatment. To overcome this challenge, a global ACT subsidy has been proposed. We tested this proposal through a pilot program in rural Tanzania. METHODS/PRINCIPAL FINDINGS: Three districts were assigned to serve either as a control or to receive the subsidy plus a package of supporting interventions. From October 2007, ACTs were sold at a 90% subsidy through the normal private supply chain to intervention district drug shops. Data were collected at baseline and during intervention using interviews with drug shop customers, retail audits, mystery shoppers, and audits of public and NGO facilities. The proportion of consumers in the intervention districts purchasing ACTs rose from 1% at baseline to 44.2% one year later (p<0.001), and was significantly higher among consumers purchasing for children under 5 than for adults (p = 0.005). No change in ACT usage was observed in the control district. Consumers paid a mean price of $0.58 for ACTs, which did not differ significantly from the price paid for sulphadoxine-pyrimethamine, the most common alternative. Drug shops in population centers were significantly more likely to stock ACTs than those in more remote areas (p<0.001). CONCLUSIONS: A subsidy introduced at the top of the private sector supply chain can significantly increase usage of ACTs and reduce their retail price to the level of common monotherapies. Additional interventions may be needed to ensure access to ACTs in remote areas and for poorer individuals who appear to seek treatment at drug shops less frequently. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN39125414

Forgotten Plotlanders: Learning from the survival of lost informal housing in the UK.

Colin Ward’s discourses on the arcadian landscape of ‘plotlander’ housing are unique documentations of the anarchistic birth, life, and death of the last informal housing communities in the UK. Today the forgotten history of ‘plotlander’ housing documented by Ward can be re-read in the context of both the apparently never-ending ‘housing crisis’ in the UK, and the increasing awareness of the potential value of learning from comparable informal housing from the Global South. This papers observations of a previously unknown and forgotten plotlander site offers a chance to begin a new conversation regarding the positive potential of informal and alternative housing models in the UK and wider Westernised world