Noise Induced Complexity: From Subthreshold Oscillations to Spiking in Coupled Excitable Systems

We study stochastic dynamics of an ensemble of N globally coupled excitable elements. Each element is modeled by a FitzHugh-Nagumo oscillator and is disturbed by independent Gaussian noise. In simulations of the Langevin dynamics we characterize the collective behavior of the ensemble in terms of its mean field and show that with the increase of noise the mean field displays a transition from a steady equilibrium to global oscillations and then, for sufficiently large noise, back to another equilibrium. Diverse regimes of collective dynamics ranging from periodic subthreshold oscillations to large-amplitude oscillations and chaos are observed in the course of this transition. In order to understand details and mechanisms of noise-induced dynamics we consider a thermodynamic limit $N\to\infty$ of the ensemble, and derive the cumulant expansion describing temporal evolution of the mean field fluctuations. In the Gaussian approximation this allows us to perform the bifurcation analysis; its results are in good agreement with dynamical scenarios observed in the stochastic simulations of large ensembles

Impact of system parameter selection on radar sensor performance in automotive applications

The paper deals with the investigation of relevant boundary conditions to be considered in order to operate 77/79 GHz narrow and ultra wide band automotive radar sensors in the automotive platform and the automotive environment

Winter 1973

Field Evaluation of Insecticides for Controlling Mole Crickets in Turf (page 3) Calculations for Turfgrass Culture II: Pesticides (6) Progress in the Control of Turfgrass Weevil, a Species of Hyperodes (9) A Look at USDA\u27s Biological Control of Insect Pests: 1888 to Present (14) Turf Bulletin Index 1970-1973 (23

Cemented vs screw-retained zirconia-based single implant reconstructions: A 3-year prospective randomized controlled clinical trial

OBJECTIVES The objective of the present randomized clinical trial was to test whether or not the use of screw-retained all ceramic implant-borne reconstructions results in clinical, technical, and biologic outcomes similar to those obtained with cemented all ceramic reconstructions. The hypothesis was that there is no difference in clinical, technical, and biological parameters between the two types of retention. MATERIALS AND METHODS Forty-four patients randomly received 20 cemented reconstruction (CR) and 24 screw-retained (SR) all ceramic single crowns on two-piece dental implants with nonmatching implant-abutment junctions. All patients were recalled after crown insertion, at 6 months, 1 year, as well as at 3 years. At these visits, biological and radiographic evaluations were performed. Technical outcomes were assessed using modified USPHS (United States Public Health Service) criteria. Data were statistically analyzed with Wilcoxon-Mann-Whitney, Wilcoxon and Fisher exact tests. RESULTS During 3 years of follow-up, eight patients (18.2%) lost the reconstruction due to technical (6 patients, 13.6%, 2 CR and 4 SR group) or biological complications (2 patients, 4.5%, only CR group). Thirty-two subjects with 18 SR and 14 CR reconstructions attended the FU-3Y, whereas four patients (9.1%, 2 SR, 2 CR) were not available (drop-outs). Biological, technical, and radiographic outcomes did not differ significantly between the groups (P > 0.05). One implant (2.3%) was lost in the CR group. One more cemented crown (2.3%) had to be removed because of peri-implant disease. Six patients (13.6%) lost the reconstructions due to a fracture of the zirconia abutment (4 SR, 2 CR). The mean marginal bone level at 3 years was -0.4 mm (-0.5; -0.3) in group SR and - 0.4 mm (-0.6; -0.3) group CR (P = 0.864). CONCLUSIONS At 3 years, CR and SR exhibited similar survival technical, biological and radiographic outcomes. The rate of technical complications was high in both groups

Shoulder load during synchronous handcycling and handrim wheelchair propulsion in persons with paraplegia

Objective: To compare the shoulder load during handcycling and wheelchair propulsion under similar conditions of external power in persons with spinal cord injury. Design: Cross-sectional. Subjects: Eight men with spinal cord injury. Methods: Kinetics and kinematics were measured during handbike and wheelchair propulsion at 25, 35, 45 and 55 W on a treadmill. Shoulder load (glenohumeral contact forces, relative muscle forces) was calculated with the Delft Shoulder and Elbow Model. Results: At all power output levels, glenohumeral contact forces were significantly lower during handcycling compared with wheelchair propulsion (p < 0.001). At 55 W, the mean glenohumeral contact force was 345 N for handcycling, whereas it was 585 N for wheelchair propulsion. Also, relative muscle forces were lower during handcycling. The largest differences between handbike and wheelchair propulsion were found in the supraspinatus (4.5% vs. 20.7%), infraspinatus (3.7% vs. 16.5%) and biceps (5.0% vs. 17.7%). Conclusion: Due to continuous force application in handcycling, shoulder load was lower compared with wheelchair propulsion. Furthermore, muscles that are prone to overuse injuries were less stressed during handcycling. Therefore, handcycling may be a good alternative for outdoor mobility and may help prevent overuse injuries of the shoulder complex. © 2012 The Authors

Collapse of Flux Tubes

The dynamics of an idealized, infinite, MIT-type flux tube is followed in time as the interior evolves from a pure gluon field to a $\overline q \ q$ plasma. We work in color U(1). $\overline q\ q$ pair formation is evaluated according to the Schwinger mechanism using the results of Brink and Pavel. The motion of the quarks toward the tube endcaps is calculated by a Boltzmann equation including collisions. The tube undergoes damped radial oscillations until the electric field settles down to zero. The electric field stabilizes the tube against pinch instabilities; when the field vanishes, the tube disintegrates into mesons. There is only one free parameter in the problem, namely the initial flux tube radius, to which the results are very sensitive. Among various quantities calculated is the mean energy of the emitted pions.Comment: 16 pages plus 12 figures. RevTex3. DOE/ER/40427-160N9

Cost-effectiveness of CTA, MRA and DSA in patients with non-traumatic subarachnoid haemorrhage

OBJECTIVES: Intra-arterial digital subtraction angiography (DSA), magnetic resonance angiography (MRA) and computed tomographic angiography (CTA) are imaging modalities used for diagnostic work-up of non-traumatic subarachnoid haemorrhage. The aim of our study was to compare the cost-effectiveness of MRA, DSA and CTA in the first year after the bleed. METHODS: A decision model was used to calculate costs and benefits (in quality-adjusted life-years [QALYs]) that accrued to cohorts of 1,000 patients. Costs and characteristics of diagnostic tests, therapy, patients’ quality of life and associated costs were respected. The diagnostic strategy with highest QALYs and lowest costs was considered most cost-effective. RESULTS: DSA was the most effective diagnostic option, yielding on average 0.6039 QALYs (95 % CI, 0.5761–0.6327) per patient, followed by CTA 0.5983 QALYs (95 % CI, 0.5704–0.6278) and MRA 0.5947 QALYs (95 % CI, 0.5674–0.6237). Cost was lowest for DSA (39,808 €; 95 % CI, 37,182–42,663), followed by CTA (40,748 €; 95 % CI, 37,937–43,831) and MRA (41,814 €; 95 % CI, 38,730–45,146). A strategy of CTA followed by DSA if CTA was negative or coiling deemed not feasible, was as effective as DSA alone at average costs of 39,767€ (95 % CI, 36,903–42,402). CONCLUSION: A combined strategy of CTA and DSA was found to be the most cost-effective diagnostic approach. MAIN MESSAGES: • We defined a standard model for cost-effectiveness analysis in diagnostic imaging. • Comparing total 1-year health costs and benefits, CTA is superior to MRA. • A strategy of combining CTA and DSA was found to be the most cost-effective diagnostic approach