Two site self consistent method for front propagation in reaction-diffusion system

We study front propagation in the reaction diffusion process $A\leftrightarrow2A$ on one dimensional lattice with hard core interaction between the particles. We propose a two site self consistent method (TSSCM) to make analytic estimates for the front velocity and are in excellent agreement with the simulation results for all parameter regimes. We expect that the simplicity of the method will allow one to use this technique for estimating the front velocity in other reaction diffusion processes as well.Comment: 6 figure

Memory-induced anomalous dynamics: emergence of diffusion, subdiffusion, and superdiffusion from a single random walk model

We present a random walk model that exhibits asymptotic subdiffusive, diffusive, and superdiffusive behavior in different parameter regimes. This appears to be the first instance of a single random walk model leading to all three forms of behavior by simply changing parameter values. Furthermore, the model offers the great advantage of analytic tractability. Our model is non-Markovian in that the next jump of the walker is (probabilistically) determined by the history of past jumps. It also has elements of intermittency in that one possibility at each step is that the walker does not move at all. This rich encompassing scenario arising from a single model provides useful insights into the source of different types of asymptotic behavior

Pseudotumor cerebri and ciprofloxacin: a case report

INTRODUCTION: We present a case of ciprofloxacin-associated pseudotumor cerebri in a 22-year-old African American woman. Withdrawal of ciprofloxacin in our patient resulted in complete resolution of ciprofloxacin-associated pseudotumor, as evidenced by a normal neuro-ophthalmic examination and a cerebrospinal fluid opening pressure of 140 mmH20. CASE PRESENTATION: A 22-year-old African American woman presented with a headache of two weeks duration, visual blurring and horizontal diplopia after starting ciprofloxacin for pyelonephritis. An ophthalmic examination revealed that she had left eye esotropia, and a picture of the fundus demonstrated bilateral disc swelling without spontaneous venous pulsations. Magnetic resonance imaging of the brain and a magnetic resonance venogram were normal. A diagnostic lumbar puncture demonstrated an elevated opening pressure of 380mmH2O in a supine position. Laboratory examinations, including a cerebrospinal fluid exam, were unremarkable. CONCLUSION: ciprofloxacin-associated pseudotumor can cause chronic disabling headache and visual complications. Therapy is sub-optimal, often symptomatic, insufficient and complicated by side effects. When ciprofloxacin-associated pseudotumor presents in an atypical population, an inciting agent must be suspected because prompt withdrawal of the agent may lead to complete resolution of symptoms and prevent recurrence of similar episodes

Type of High-School Credentials and Older Age ADL and IADL Limitations: Is the GED Credential Equivalent to a Diploma?

Purpose: Educational attainment is a robust predictor of disability in elderly Americans: older adults with high-school (HS) diplomas have a substantially lower disability than individuals who did not complete HS. General Educational Development (GED) diplomas now comprise almost 20% of new HS credentials issued annually in the United States but it is unknown whether the apparent health advantages of HS diplomas extend to GED credentials. This study examines whether adults older than 50 years with GEDs have higher odds of incident instrumental or basic activities of daily living (IADLs) limitations compared with HS degree holders. Methods: We compared odds of incident IADL limitations by HS credential type using discrete-time survival models among 9,426 Health and Retirement Study participants followed from 1998 through 2008. Results: HS degree holders had lower odds of incident IADLs than GED holders (OR = 0.72, 95% CI = 0.58, 0.90 and OR = 0.69, 95% CI = 0.56, 0.86 for ADLs and IADLs, respectively). There was no significant difference in odds of incident IADL limitations between GED holders and respondents without HS credentials (OR = 0.89, 95% CI = 0.71, 1.11 for ADLs; OR = 0.88, 95% CI = 0.70, 1.12 for IADLs).Implications: Although GEDs are widely accepted as equivalent to high school diplomas, they are not associated with comparable health advantages for physical limitations in older age