Deriving the respiratory sinus arrhythmia from the heartbeat time series using Empirical Mode Decomposition

Heart rate variability (HRV) is a well-known phenomenon whose characteristics are of great clinical relevance in pathophysiologic investigations. In particular, respiration is a powerful modulator of HRV contributing to the oscillations at highest frequency. Like almost all natural phenomena, HRV is the result of many nonlinearly interacting processes; therefore any linear analysis has the potential risk of underestimating, or even missing, a great amount of information content. Recently the technique of Empirical Mode Decomposition (EMD) has been proposed as a new tool for the analysis of nonlinear and nonstationary data. We applied EMD analysis to decompose the heartbeat intervals series, derived from one electrocardiographic (ECG) signal of 13 subjects, into their components in order to identify the modes associated with breathing. After each decomposition the mode showing the highest frequency and the corresponding respiratory signal were Hilbert transformed and the instantaneous phases extracted were then compared. The results obtained indicate a synchronization of order 1:1 between the two series proving the existence of phase and frequency coupling between the component associated with breathing and the respiratory signal itself in all subjects.Comment: 12 pages, 6 figures. Will be published on "Chaos, Solitons and Fractals

Short-Term Effect of Daily Herbage Allowance Restriction on Pasture Condition and the Performance of Grazing Dairy Cows during Autumn

The aim of this study was to evaluate the short-term effects of daily herbage allowance (DHA, defined as the product of pre-grazing herbage mass and offered area per animal) on pasture conditions and milk production of Holstein-Friesian dairy cows. Forty-four early lactation dairy cows were randomly assigned to one of four treatments in a 2 × 2 factorial design that tested two levels of DHA (17 and 25 kg DM/cow.day) and two levels of maize silage supplementation (MSS, 4.5 and 9 kg DM/cow.day) over a 77-day period. Low DHA decreased the post-grazing herbage mass from 1546 to 1430 kg DM/ha and the compressed sward height from 5 to 4.4 cm, while the grazing efficiency remained unaffected. Low DHA induced a faster herbage mass reduction, while the sward-height and pasture characteristics did not differ from the high DHA regime. Low DHA decreased the tiller production rates and daily lamina growth, while the leaf-production rate was not affected by the DHA. Daily increases of herbage mass were greater in the high DHA than in the low DHA treatments. Individual milk production and milk protein concentration decreased at a low DHA compared to high DHA, while the milk fat concentration was greater and the milk output per hectare increased by 1510 kg. Neither the MSS level nor the interaction DHA by the MSS level had any effect on the sward characteristics or the productivity of the cows. From these results, it is suggested that,in a high-quality pasture, using 17 kg DM/cow.day was appropriate for improving both herbage utilization and milk production per hectare while maintaining the short-term conditions of a pasture grazed by dairy cows in the autumn

Uncovering Patterns for Adverse Pregnancy Outcomes with Spatial Analysis: Evidence from Philadelphia

We introduce a spatial model for analyzing patient-specific and neighborhood risks of stillbirth and preterm birth in Philadelphia. Using electronic health records and census tract data, we find that both patient-level characteristics (e.g. self-identified race/ethnicity) and neighborhood-level characteristics (e.g. violent crime) are associated with patients' odds of stillbirth or preterm birth. Census tracts with higher rates of women in poverty or on public assistance have greater neighborhood risk for these outcomes, whereas census tracts with higher rates of college-educated women or women in the labor force have lower risk. Our findings could be useful for targeted individual and neighborhood interventions.Comment: 27 pages, 7 figures, 9 table

Las narrativas experimentales en la enseñanza de la Química

El presente trabajo versa sobre la inclusión de las narrativas experimentales en la escuela para promover habilidades cognitivo ligüísticas específicas. Los datos sobre la actividad de los y las estudiantes, ideas y acciones se obtienen a partir de las narrativas experimentales creadas por ellos a partir del trabajo de laboratorio realizado

RAPD and freezing resistance in Eucalyptus globulus

Eucalyptus globulus is the second most important forest species in Chile, after Pinus radiata . The main advantages of E. globulus are its fast growth (25 m3/ha/year) and its excellent wood quality for kraft pulp production. On the negative side, its low freezing tolerance has been an obstacle for the expansion of plantations, specifically on the foothills of the Andes. The difference in the freezing resistance between clones of E. globulus has a genetic base and, therefore, it could be detected through DNA molecular markers. Fifteen clones of E. globulus, eight classified as freezing resistant and seven as freezing sensitive were analyzed using the technique of RAPD, in order to obtain molecular markers that could differentiate between freezing sensitive and resistant clones. Eighteen primers amplified reproducible bands. Three bands were only present in freezing resistant clones, two bands of 768 bp, 602 bp obtained with UBC 218 primer and one band of 248 bp obtained with UBC 237 primer. The preliminary results indicate that polymorphism can be observed with the primers employed, but it is not possible to associate the bands with the cold resistance or susceptibility in E. globulus

RAPD and freezing resistance in Eucalyptus globulus

Eucalyptus globulus is the second most important forest species in Chile , after Pinus radiata. The main advantages of E. globulus are its fast growth (25 m3/ha/year) and its excellent wood quality for kraft pulp production. On the negative side, its low freezing tolerance has been an obstacle for the expansion of plantations, specifically on the foothills of the Andes . The difference in the freezing resistance between clones of E. globulus has a genetic base and, therefore, it could be detected through DNA molecular markers. Fifteen clones of E. globulus, eight classified as freezing resistant and seven as freezing sensitive were analyzed using the technique of RAPD, in order to obtain molecular markers that could differentiate between freezing sensitive and resistant clones. Eighteen primers amplified reproducible bands. Three bands were only present in freezing resistant clones, two bands of 768 bp, 602 bp obtained with UBC 218 primer and one band of 248 bp obtained with UBC 237 primer. The preliminary results indicate that polymorphism can be observed with the primers employed, but it is not possible to associate the bands with the cold resistance or susceptibility in E. globulus

Changes in Cardiac Autonomic Regulation after Acute Lung Exposure to Carbon Nanotubes: Implications for Occupational Exposure

Carbon nanotubes (CNTs) are among the most relevant engineered nanomaterials (ENMs). Given the expected rise of exposure to ENMs, there is concern that they may adversely affect health of exposed people. Aim of the study was to test the hypothesis that single wall carbon nanotubes (SWCNTs) pulmonary exposure acutely affect the autonomic cardiovascular regulation in conscious rats. We studied Wistar-Kyoto rats in which a telemetry transmitter for continuous arterial pressure (AP) and heart rate (HR) recordings was surgically implanted. SWCNTs dispersed in phosphate buffer saline (PBS) or PBS alone were randomly administered intratracheally. Immediately before, and 24 hours after each instillation a 30 min AP recording was performed. The sequence analysis was performed to evaluate the baroreflex function. In the control group, PBS instillation did not induce any significant changes. At variance the SWCNT exposure induced a significant reduction of baroreflex system (BRS) (3.5 \ub1 0.6 versus 2.6 \ub1 0.40\u2009msec/mmHg) without significant changes in the occurrence of baroreflex sequences (7.5 \ub1 0.47 % versus 7.4 \ub1 0.38 %). Our results show that SWCNT pulmonary exposure might affect the cardiovascular autonomic regulation thus contributing to cardiac and arrhythmic events