Parametric estimation of pulse arrival time: a robust approach to pulse wave velocity

Pulse wave velocity (PWV) is a surrogate of arterial stiffness and represents a non-invasive marker of cardiovascular risk. The non-invasive measurement of PWV requires tracking the arrival time of pressure pulses recorded in vivo, commonly referred to as pulse arrival time (PAT). In the state of the art, PAT is estimated by identifying a characteristic point of the pressure pulse waveform. This paper demonstrates that for ambulatory scenarios, where signal-to-noise ratios are below 10 dB, the performance in terms of repeatability of PAT measurements through characteristic points identification degrades drastically. Hence, we introduce a novel family of PAT estimators based on the parametric modeling of the anacrotic phase of a pressure pulse. In particular, we propose a parametric PAT estimator (TANH) that depicts high correlation with the Complior(R) characteristic point D1 (CC = 0.99), increases noise robustness and reduces by a five-fold factor the number of heartbeats required to obtain reliable PAT measurements.

DMG-Lib - The Digital Mechanism and Gear Library

Motion systems are important parts of technical products. Those are mostly composed of mechanisms and gears. Today mechanism and gear technology is essential for the whole industry and it will become even more important due to the introduction of new technologies and respective new fields of applications.

Illegitimate tasks associated with higher cortisol levels among male employees when subjective health is relatively low: an intra-individual analysis

Objectives Illegitimate tasks refer to tasks that do not conform to what can appropriately be expected from an employee. Violating role expectations, they constitute “identity-stressors”, as one’s professional role tends to become part of one’s identity. The current study investigated the impact of illegitimate tasks on salivary cortisol. We analyzed data on an intra-individual level, that is, by examining fluctuations in illegitimate tasks and cortisol within individuals. Furthermore, we investigated the moderating role of perceived health, expecting that illegitimate tasks evoke stronger reactions when perceived health is relatively poor. Methods Illegitimate tasks, salivary cortisol, and perceived health were assessed in each of three waves (time lag: 6 months) in a sample of 104 male employees. Data were analyzed by multilevel analysis using group mean centering. Results Controlling for social stressors, work interruptions, and emotional stability, the experience of more illegitimate tasks was associated with increased cortisol release if personal health resources were low compared to one’s mean value of perceived health. Results cannot be explained by inter-individual differences. Conclusions This is the first study showing that illegitimate tasks predict a biological indicator of stress, thus confirming and extending previous research on illegitimate tasks. The moderating role of perceived health confirms its importance as a personal resource, implying augmented vulnerability when perceived health is below its usual value. It is plausible to assume that increased stress reactions due to relatively poor health may further weaken available personal resources. Both avoiding illegitimate tasks and restoring personal health seem to be crucial.

An optimized lead system for long-term esophageal electrocardiography

Long-term electrocardiography (ECG) featuring adequate atrial and ventricular signal quality is highly desirable. Routinely used surface leads are limited in atrial signal sensitivity and recording capability impeding complete ECG delineation, i.e. in the presence of supraventricular arrhythmias. Long-term esophageal ECG might overcome these limitations but requires a dedicated lead system and recorder design. To this end, we analysed multiple-lead esophageal ECGs with respect to signal quality by describing the ECG waves as a function of the insertion level, interelectrode distance, electrode shape and amplifier's input range. The results derived from clinical data show that two bipolar esophageal leads, an atrial lead with short (15 mm) interelectrode distance and a ventricular lead with long (80 mm) interelectrode distance provide non-inferior ventricular signal strength and superior atrial signal strength compared to standard surface lead II. High atrial signal slope in particular is observed with the atrial esophageal lead. The proposed esophageal lead system in combination with an increased recorder input range of ±20 mV minimizes signal loss due to excessive electrode motion typically observed in esophageal ECGs. The design proposal might help to standardize long-term esophageal ECG registrations and facilitate novel ECG classification systems based on the independent detection of ventricular and atrial electrical activity.

CCDC26, CDKN2BAS, RTEL1 and TERT Polymorphisms in pediatric brain tumor susceptibility.

The role of genetic polymorphisms in pediatric brain tumor (PBT) etiology is poorly understood. We hypothesized that single nucleotide polymorphisms (SNPs) identified in genome-wide association studies (GWAS) on adult glioma would also be associated with PBT risk. The study is based on the Cefalo study, a population-based multicenter case-control study. Saliva DNA from 245 cases and 489 controls, aged 7-19 years at diagnosis/reference date, was extracted and genotyped for 29 SNPs reported by GWAS to be significantly associated with risk of adult glioma. Data were analyzed using unconditional logistic regression. Stratified analyses were performed for two histological subtypes: astrocytoma alone and the other tumor types combined. The results indicated that four SNPs, CDKN2BAS rs4977756 (p = 0.036), rs1412829 (p = 0.037), rs2157719 (p = 0.018) and rs1063192 (p = 0.021), were associated with an increased susceptibility to PBTs, whereas the TERT rs2736100 was associated with a decreased risk (p = 0.018). Moreover, the stratified analyses showed a decreased risk of astrocytoma associated with RTEL1 rs6089953, rs6010620 and rs2297440 (p trend = 0.022, p trend = 0.042, p trend = 0.029, respectively) as well as an increased risk of this subtype associated with RTEL1 rs4809324 (p trend = 0.033). In addition, SNPs rs10464870 and rs891835 in CCDC26 were associated with an increased risk of non-astrocytoma tumor subtypes (p trend = 0.009, p trend = 0.007, respectively). Our findings indicate that SNPs in CDKN2BAS, TERT, RTEL1 and CCDC26 may be associated with the risk of PBTs. Therefore, we suggest that pediatric and adult brain tumors might share common genetic risk factors and similar etiological pathways.

Correlation between alveolar ventilation and electrical properties of lung parenchyma.

One key problem in modern medical imaging is linking measured data and actual physiological quantities. In this article we derive such a link between the electrical bioimpedance of lung parenchyma, which can be measured by electrical impedance tomography (EIT), and the magnitude of regional ventilation, a key to understanding lung mechanics and developing novel protective ventilation strategies. Two rat-derived three-dimensional alveolar microstructures obtained from synchrotron-based x-ray tomography are each exposed to a constant potential difference for different states of ventilation in a finite element simulation. While the alveolar wall volume remains constant during stretch, the enclosed air volume varies, similar to the lung volume during ventilation. The enclosed air, serving as insulator in the alveolar ensemble, determines the resulting current and accordingly local tissue bioimpedance. From this we can derive a relationship between lung tissue bioimpedance and regional alveolar ventilation. The derived relationship shows a linear dependence between air content and tissue impedance and matches clinical data determined from a ventilated patient at the bedside.

Lipids in ocean particulate matter and bottom sediments

Lipid contents both in particulate matter and bottom sediments decreases with passage from the shelf toward the open ocean. Lipid concentration in particulate matter collected by a separator (Ls) decreases by a factor of 7 (from 7.05 to 0.95 % of dry matter), while in particulate matter collected on filters (Lf) it decreases by a factor of 13 (from 78 to 6 µg/l) in the vicinity of the Limpopo River and by a factor of 6 (from 74 to 13 µg/l) in the vicinity of the Zambezi River. Concentration of Lf also decreased with depth. In the upper sediment layers lipid concentration was 0.0028-0.039% of dry matter; all mud samples were richer in lipids, than sand samples. During sedimentogenesis there is an increase in proportion of lipids relative to other classes of organic matter, proportion of low-polarity compounds increases among the lipids, and proportion of hydrocarbons rises among these compounds. Sediments inherit composition of particulate matter to the greatest degree in the vicinity of river mouths.

La investigación en alfabetización en información en Uruguay : presente y desarrollos futuros

Se describe el estado de situación de la investigación en alfabetización en información en Uruguay. Se presenta el contexto académico en el cual se está desarrollando dicha línea de investigación, desde la conformación de un grupo de investigación interdisciplinar que tiene su centro en el Programa de Desarrollo Académico de la Información y la Comunicación (PRODIC) de la Universidad de la República. Se hace referencia a proyectos de investigación de grado, posgrado que se han realizado y/o se están llevando a cabo con miras a fortalecer la línea de investigación y apuntar a su proyección de futuro. Se enfatiza principalmente en la Maestría en Información y Comunicación como ámbito natural de promoción de la investigación de calidad. Se mencionan los vínculos académicos generados a nivel regional e internacional que propician la implementación de investigaciones, proyectos y publicaciones conjuntas. En suma, se comparte con el colectivo académico bibliotecológico los avances y perspectivas de futuro de la investigación de una temática de gran relevancia en la actual sociedad de la información y el conocimiento, a partir de la sistematización y la acumulación de conocimiento sobre el tema