Entrainment and chaos in a pulse-driven Hodgkin-Huxley oscillator

The Hodgkin-Huxley model describes action potential generation in certain types of neurons and is a standard model for conductance-based, excitable cells. Following the early work of Winfree and Best, this paper explores the response of a spontaneously spiking Hodgkin-Huxley neuron model to a periodic pulsatile drive. The response as a function of drive period and amplitude is systematically characterized. A wide range of qualitatively distinct responses are found, including entrainment to the input pulse train and persistent chaos. These observations are consistent with a theory of kicked oscillators developed by Qiudong Wang and Lai-Sang Young. In addition to general features predicted by Wang-Young theory, it is found that most combinations of drive period and amplitude lead to entrainment instead of chaos. This preference for entrainment over chaos is explained by the structure of the Hodgkin-Huxley phase resetting curve.Comment: Minor revisions; modified Fig. 3; added reference

Hydrochemical Denudation and Transient Carbon Dioxide Drawdown in the Highly Glacierized, Shrinking Koxkar Basin, China

This study considered solute fluxes and the transient CO2 drawdown process in the highly glacierized Koxkar basin in Central Eurasia, around 70.20% of which is covered by present-day ice. From 27 June to 30 September 2011, the total runoff depth was 671.70 mm, which yielded crustal solute fluxes of 213.65 ± 10.05 kg·(km2·d)−1 that accounted for 53.59% of the total solute flux of the river water. The solute fluxes derived directly from ice meltwater and precipitation were 70.02 ± 4.68 and 16.57 ± 1.13 kg·(km2·d)−1, respectively, which accounted for 17.57% and 4.16% of the total solute flux. The carbonation and hydrolysis of carbonate and feldspar minerals occurred because of the presence of H+, supplied by sulfide oxidation or CO2 drawdown. While the H+ yielded by sulfide oxidation was insufficient for hydrochemical reactions, atmospheric CO2 dissolved in the water generated H+ that drove follow-up reactions. The total transient drawdown of CO2 was 804.83 t C, which generated 39.61% of the total HCO3- and 24.68% of the river water solute. Transient drawdown of CO2 in the glacier region indicated that change of glacial area and volume could influence atmospheric CO2 concentration and be important in the long-term global CO2 cycle

Actigraph Evaluation of Acupuncture for Treating Restless Legs Syndrome

We evaluated the effects of acupuncture in patients with restless legs syndrome (RLS) by actigraph recordings. Among the 38 patients with RLS enrolled, 31 (M=12, F=19; mean age, 47.2±9.7 years old) completed the study. Patients were treated with either standard acupuncture n=15 or randomized acupuncture n=16 in a single-blind manner for 6 weeks. Changes in nocturnal activity (NA) and early sleep activity (ESA) between week 0 (baseline), week 2, week 4, and week 6 were assessed using leg actigraph recordings, the International Restless Legs Syndrome Rating Scale (IRLSRS), and Epworth Sleepiness Scale (ESS). Standard but not randomized acupuncture reduced the abnormal leg activity of NA and ESA significantly in week 2, week 4, and week 6 based on the changes in the clinical scores for IRLSRS and ESS in week 4 and week 6 compared with the baseline. No side effects were observed. The results indicate that standard acupuncture might improve the abnormal leg activity in RLS patients and thus is a potentially suitable integrative treatment for long-term use

The Use of Integrative Therapies in Patients with Amyotrophic Lateral Sclerosis in Shanghai, China

Objective. To investigate the current use of integrative therapies (IT) in the treatment of patients with amyotrophic lateral sclerosis (ALS). Methods. A cross-sectional, multicenter clinical epidemiological survey was conducted in 12 hospitals in Shanghai. We investigated the type and frequency of IT use and determined whether the use of IT correlated with demographic, social, or disease-specific characteristics in our patient population. Results. A total of 231 (89.5%) of 258 patients with ALS were eligible for the study and 229 (99% of all) of 231 reported the use of at least one IT for the treatment of ALS. Vitamins and Chinese herb decoctions, Chinese herb compounds, massage therapy, and acupuncture were the 5 most commonly used therapies. There was a strong association between education level, income, and use of IT. A household income of more than 75,000 RMB ($49,995) correlated with multiple IT use, and married patients used IT more often than single individuals. The main reasons for using IT were to treat weakness and fatigue, muscle atrophy, the development of ALS, depression, insomnia, limb pain or numbness, and side effects associated with Riluzole. Conclusion. The use of IT is common in patients with ALS in Shanghai. Vitamins and TCM are the most used additional therapies and the widespread and largely unexamined use of IT for ALS requires more attention