Analysis of atrial fibrillation: from electrocardiogram signal processing to clinical management

The analysis of atrial fibrillation in non-invasive ECG recordings has received considerable attention in recent years, spurring the development of signal processing techniques for more advanced characterization of the atrial waveforms than previously available. The present paper gives an overview of different approaches to the extraction of atrial activity in the ECG and to the characterization of the resulting atrial signal with respect to its spectral properties. So far, the repetition rate of the atrial waves is the most studied parameter and its significance in clinical management is briefly considered, including the identification of pathomechanisms and prediction of therapy efficacy.     

Affirmed yet unaware: Exploring the role of awareness in the process of self-affirmation.

Three studies investigated whether self-affirmation can proceed without awareness, whether people are aware of the influence of experimental self-affirmations, and whether such awareness facilitates or undermines the self-affirmation process. The authors found that self-affirmation effects could proceed without awareness, as implicit self-affirming primes (utilizing sentence-unscrambling procedures) produced standard self-affirmation effects (Studies 1 and 3). People were generally unaware of self-affirmation’s influence, and self-reported awareness was associated with decreased impact of the affirmation (Studies 1 and 2). Finally, affirmation effects were attenuated when people learned that self-affirmation was designed to boost self-esteem (Study 2) or told of a potential link between self-affirmation and evaluations of threatening information (Study 3). Together, these studies suggest not only that affirmation processes can proceed without awareness but also that increased awareness of the affirmation may diminish its impact. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Occurrence of pharmaceuticals in river water and their elimination in a pilot-scale drinking water treatment plant

The occurrence of four beta blockers, one antiepileptic drug, one lipid regulator, four anti-inflammatories, and three fluoroquinolones was studied in a river receiving sewage effluents. All compounds but two of the fluoroquinolones were observed in the water above their limit of quantification concentrations. The highest concentrations (up to 107 ng L(-1)) of the compounds were measured during the winter months. The river water was passed to a pilot-scale drinking water treatment plant, and the elimination of the pharmaceuticals was followed during the treatment. The processes applied by the plant consisted of ferric salt coagulation, rapid sand filtration, ozonation, two-stage granular activated carbon filtration (GAC), and UV disinfection. Following the coagulation, sedimentation, and rapid sand filtration, the studied pharmaceuticals were found to be eliminated only by an average of 13%. An efficient elimination was found to take place during ozonation at an ozone dose of about 1 mg L(-1) (i.e., 0.2-0.4 mg of O3/ mg of TOC). Following this treatment, the concentrations of the pharmaceuticals dropped to below the quantification limits with the exception of ciprofloxacin. Atenolol, sotalol, and ciprofloxacin, the most hydrophilic of the studied pharmaceuticals, were not fully eliminated during the GAC filtrations. All in all, the treatment train was found to very effectively eliminate the pharmaceuticals from the rawwater. The only compound that was found to pass almost unaffected through all the treatment steps was ciprofloxacin.     

Effects of climate change on biomass production and substitution in north-central Sweden

In this study we estimate the effects of climate change on forest production in north-central Sweden, as well as the potential climate change mitigation feedback effects of the resulting increased carbon stock and forest product use. Our results show that an average regional temperature rise of 4 °C over the next 100 years may increase annual forest production by 33% and potential annual harvest by 32%, compared to a reference case without climate change. This increased biomass production, if used to substitute fossil fuels and energy-intensive materials, can result in a significant net carbon emission reduction. We find that carbon stock in forest biomass, forest soils, and wood products also increase, but this effect is less significant than biomass substitution. A total net reduction in carbon emissions of up to 104 Tg of carbon can occur over 100 years, depending on harvest level and reference fossil fuel.     

The human side of the road: Improving the working conditions of urban bus drivers.

This study evaluated how urban bus drivers' well-being was affected by technical interventions designed to improve the traffic environment of an urban bus route. Three questionnaires were distributed; 8 drivers at the intervention route (mean age 43 years) and 13 demographically matched comparison drivers (mean age 39 years) participated at all occasions. Field studies at work were conducted twice, with 10 intervention route drivers (mean age 43 years) and 31 comparison drivers (mean age 42 years). The authors hypothesized that during the course of the intervention, the initially elevated indexes of occupational stress in the intervention group would be reduced to levels equivalent to those of the comparison group. The hypothesis was confirmed for perceived workload in the questionnaire, observer-rated job hassles, systolic blood pressure and heart rate at work, and perceived distress after work in the field study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructure and its effect on toughness and wear resistance of laser surface melted and post heat treated high speed steel

High speed steel hacksaw blade blanks were laser surface melted and rapidly solidified along one edge. The laser melting resulted in complete carbide dissolution. By subsequent machining and heat treatments saw teeth were manufactured with a refined internal structure of the edges and corners. The structure was fully martensitic with a uniform and dense dispersion of small primary carbides. Sawing tests in quenched and tempered steel showed that blade life was somewhat improved, as compared to conventionally heat treated blades. The increased wear resistance is believed to be due to improved toughness along with high hardness caused by the refined carbide structure. Sawing tests in austenitic stainless steel did not give any significant improvement in performance. The effect of the altered microstructure on performance is likely to be more or less pronounced depending on application, tool and work material.     

Subfractionation and characterization of native and incubation enlarged human plasma high density lipoprotein particles by high performance gel filtration

Incubation of human plasma in vitro at 37 C results in an increase of the mean particle size of the high density lipoproteins (HDL) accompanied by an almost complete disappearance of the original particles present prior to incubation. A rapid high performance gel filtration technique has been developed in order to study the chemical composition of subfractions of native and incubation enlarged HDL particles as a function of particle size. Subfractionation of HDL isolated by preparative ultracentrifugation from 3 normal human plasmas incubaed in vitro at 0 and 37 C for 24 hr have been performed using a 150 cm long TSK-G 3000 SW column. The separation time was less than 65 min. The curves obtained at high performance gel filtration of HDL, by monitoring the effluents from the column at 280 nm, agreed well both in positions of peak maxima and relative peak intensities with the particle distribution patterns observed at polyacrylamide gradient gel electrophoresis of the corresponding HDL preparations run in parallel. The different HDL particle subfractions of the effluents from the gel filtration column have been characterized by quantification of free and esterified cholesterol, total phospholipids and apolipoprotein A-I and A-II. The incubation enlarged HDL particles, subfractionated by the high performance gel filtration technique, were found to have a composition which differed from that of native HDL particles of corresponding size. Incubation enlarged HDL had a generally higher and almost constant relative cholesteryl ester content over the whole particle range compared to native HDL in which a continuous increase in relative cholesteryl ester content could be observed when going from large to small particles. The molar ratio of phospholipids to free cholesterol was higher in small native HDL particles than in the corresponding large ones. The relation between apolipoprotein A-I and A-II remained nearly constant between small and large HDL particles in each subfractionation experiment. The results demonstrate that the high performance gel filtration technique is a rapid and reproducible means for studying the composition of subfractions of HDL particle populations.     

Using Subdivision on Hierarchical Data to Reconstruct Radiosity Distribution

Computing global illumination by finite element techniques usually generates a piecewise constant approximation of the radiosity distribution on surfaces. Directly displaying such scenes generates artefacts due to discretization errors. We propose to remedy this drawback by considering the piecewise constant output to be samples of a (piecewise) smooth function in object space and reconstruct this function by applying a binary subdivision scheme. We design custom taylored subdivision schemes with quadratic precision for the efficient refinement of cell- or pixel-type data. The technique naturally allows to reconstruct functions from non-uniform samples which result from adaptive binary splitting of the original domain (quadtree). This type of output is produced, e.g., by hierarchical radiosity algorithms. The result of the subdivision process can be mapped as a texture on the respective surface patch which allows to exploit graphics hardware for considerably accelerating the display.     

Kinetics of homogeneous catalytic chlorination of acetic acid

The kinetics of the chlorination of acetic acid (HAc) to monochloroacetic acid (MCA) and the physical solubility of chlorine in HAc and its mixtures with MCA were investigated in a laboratory scale semibatch reactor. The temperature dependence of the Henry's constant was determined from solubility data obtained at temperatures between 70°C and 110°C. The kinetic experiments were performed at 75–100°C with 3–13 mol % acetyl chloride (AcCl) and 0–5 weight % H₂SO₄ added as catalysts. Gas chromatography was used to determine the concentrations of HAc, MCA, dichloroacetic acid and AcCl during the experiments. The results indicate that the reaction rate is independent of the concentrations of HAc and Cl₂ whereas the reaction is significantly enhanced by MCA and H₂SO₄. The effects are explained by a reaction mechanism involving the acid catalyzed enolization of AcCl as the rate-determining step. A rate equation based on this mechanism was derived. Kinetic constants included in the equation were determined by regression analysis.     

Blood‐brain barrier permeability in rats exposed to electromagnetic fields used in wireless communication

Biological effects of radio frequency electromagnetic fields (EMF) on the bloodbrain barrier (BBB) have been studied in Fischer 344 rats of both sexes. The rats were not anaesthetised during the exposure. All animals were sacrificed by perfusion–fixation of the brains under chloralhydrate anaesthesia after the exposure. The brains were perfused with saline for 3–4 minutes, and thereafter perfusion fixed with 4% formaldehyde for 5–6 minutes. Whole coronal sections of the brains were dehydrated and embedded in paraffin and sectioned at 5 µm. Albumin and fibrinogen were demonstrated immunohistochemically and classified as normal versus pathological leakage. In the present investigation we exposed male and female Fischer 344 rats in a Transverse Electromagnetic Transmission line chamber to microwaves of 915 MHz as continuous wave (CW) and pulsemodulated with different pulse power and at various time intervals. The CWpulse power varied from 0.001 W to 10 W and the exposure time from 2 min to 960 min. In each experiment we exposed 4–6 rats with 2–4 controls randomly placed in excited and nonexcited TEMcells respectively. We have in total investigated 630 exposed rats at various modulation frequencies and 372 controls. The frequency of pathological rats is significantly increased (p < 0.0001) from 62/372 (ratio: 0.17 ± 0.02) for control rats to 244/630 (ratio: 0.39 ± 0.03) in all exposed rats. Grouping the exposed animals according to the level of specific absorbed energy (J/kg) give significant difference in all levels above 1.5 J/kg. The exposure was 915 MHz microwaves either pulse modulated (PW) at 217 Hz with 0.57 ms pulse width, at 50 Hz with 6.6 ms pulse width or continuous wave (CW). The frequency of pathological rats (0.17) among controls in the various groups is not significantly different. The frequency of pathological rats was 170/481 (0.35 ± 0.03) among rats exposed to pulse modulated (PW) and 74/149 (0.50 ±0.07) among rats exposed to continuous wave exposure (CW). These results are both highly significantly different to their corresponding controls (p <0.0001) and the frequency of pathological rats after exposure to pulsed radiation (PW) is significantly less (p < 0.002) than after exposure to continuous radiation (CW).