Statistical Coding and Decoding of Heartbeat Intervals

The heart integrates neuroregulatory messages into specific bands of frequency, such that the overall amplitude spectrum of the cardiac output reflects the variations of the autonomic nervous system. This modulatory mechanism seems to be well adjusted to the unpredictability of the cardiac demand, maintaining a proper cardiac regulation. A longstanding theory holds that biological organisms facing an ever-changing environment are likely to evolve adaptive mechanisms to extract essential features in order to adjust their behavior. The key question, however, has been to understand how the neural circuitry self-organizes these feature detectors to select behaviorally relevant information. Previous studies in computational perception suggest that a neural population enhances information that is important for survival by minimizing the statistical redundancy of the stimuli. Herein we investigate whether the cardiac system makes use of a redundancy reduction strategy to regulate the cardiac rhythm. Based on a network of neural filters optimized to code heartbeat intervals, we learn a population code that maximizes the information across the neural ensemble. The emerging population code displays filter tuning proprieties whose characteristics explain diverse aspects of the autonomic cardiac regulation, such as the compromise between fast and slow cardiac responses. We show that the filters yield responses that are quantitatively similar to observed heart rate responses during direct sympathetic or parasympathetic nerve stimulation. Our findings suggest that the heart decodes autonomic stimuli according to information theory principles analogous to how perceptual cues are encoded by sensory systems

Kondo effect in underdoped n-type superconductors

We present high-field magnetotransport properties of high-quality single-crystalline thin films of heavily underdoped nonsuperconducting (La,Ce)2CuO4, (Pr,Ce)2CuO4, and (Nd,Ce)2CuO4. All three materials show identical behavior. They are metallic at high temperatures and show an insulating upturn at low temperatures. The insulating upturn has a log T dependence, but saturates toward the lowest temperatures. Notably, the insulating upturn tends to be suppressed by applying magnetic fields. This negative magnetoresistance has a log B dependence, and its anisotropy shows non simple behavior. We discuss these findings from the viewpoints of Kondo scattering and also two-dimensional weak localization, and demonstrate Kondo scattering as a more plausible explanation. The Kondo scatters are identified as Cu2+ spins in the CuO2 planes.Comment: 17 pages, 6 figures, submitted to Phys. Rev. Let

Sn-Ag系鉛フリーはんだの接合性と各種特性評価に関する研究

首都大学東京, 2010-03-25, 博士(工学

Correlation of total medical cost for all-cause hospitalizations with total hospitalization days during the past 3-year period.

<p>In both the possible heart failure (pHF)-positive (A) and negative patients (B), there was a positive strong correlation between total medical cost and hospitalization days.</p

Hospitalization and medical cost of patients with elevated serum N-terminal pro-brain natriuretic peptide levels

<div><p>Background</p><p>Patients with heart failure (HF) are reportedly at high risk for ‘all-cause’ re-hospitalization. A biomarker for HF, N-terminal pro-brain natriuretic peptide (NT-proBNP), enables to simply detect patients with possible HF (pHF). We examined the hospitalization and medical cost of Japanese patients detected by an elevated serum NT-proBNP, and also evaluated the effects of institutional team approaches for HF on their all-cause hospitalizations.</p><p>Methods</p><p>We retrospectively extracted all adult patients with serum NT-proBNP ≥400 pg/ml measured between January and March 2012 in Hiroshima University Hospital as pHF-positive patients. We studied their all-cause hospitalization records during the past 3-year period. We also extracted all pHF-negative patients with NT-proBNP <400 pg/ml and studied as well. In the pHF-positive patients followed for 3 years after starting interprofessional team approaches to prevent the onset and exacerbation of HF in the hospital, we compared the hospitalization and medical cost between the 3-year periods before and after the start of the team approaches.</p><p>Results</p><p>We enrolled 432 pHF-positive and 485 pHF-negative patients with one or more hospitalization records. Compared to the pHF-negative patients, the pHF-positive patients had longer total hospitalization days (median [interquartile range], 30 [13–58] versus. 18 [8–39], p <0.0001) and higher total medical cost for hospitalizations (2.42 [1.07–5.08] versus. 1.80 [0.79–3.65] million yen, p <0.0001). A subset of 303 pHF-positive patients was followed for 3 years after starting the team approaches, and we found that both total hospitalization days (30 [13–57] to 8 [0–31]) and medical cost for hospitalizations (2.59 [1.37–5.05] to 0.76 [0–2.38] million yen) showed marked reduction in them.</p><p>Conclusions</p><p>Patients with an elevated serum NT-proBNP have longer hospitalizations and higher costs for all-cause hospitalizations than those without. Institutional team approaches for HF may reduce them.</p></div

Hospitalizations of pHF-positive patients before and after the start of team approaches for HF patients.

<p>Hospitalizations of pHF-positive patients before and after the start of team approaches for HF patients.</p