Aging or disease? Cardiovascular reactivity in Finnish men over the middle years.

Cardiovascular responses to psychological events may mediate the influence of stress on cardiovascular disease. In this study the authors asked whether cardiovascular responses to psychological challenge changed with age and whether such changes were intrinsic to aging or could be attributed to the influence of disease and medications. Cardiovascular reactivity to mental challenge was examined in 902 men ranging in age from 46 to 64 years who participated in the Kuopio Ischemic Heart Disease Risk Factor Study. A battery of 4 tasks was used to induce cardiovascular responses. Current disease status, age, and medication use were entered into hierarchical regression analyses to assess their relation with measures of cardiovascular reactivity. Age and hypertension contributed independent, approximately equal, but small amounts of variance in the cardiac and vascular reactivity indexes. Medications also influenced reactivity independently of age and disease. Performance on the tasks was more consistently altered by age than by disease or medication. Cardiac and vascular reactivity increased with increasing age and the presence of hypertension. The authors conclude that both age and disease state must be considered when examining cardiovascular reactivity as a risk factor for disease. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Using dataflow in a system of multiple single board computers

The concept of dataflow is usually limited to totally new computer structures. This paper discusses the simulation of dataflow in a symmetric system of standard microcomputer modules. The approach has advantages in that the parallelism of the computation can be expressed and handled in a natural way. The simulation of the dataflow semantics takes, however, hundreds of machine instructions for each actor execution and quite long actors are needed to keep the overhead low. The implementation of a dataflow computation using the adaptive trapezoid method for numerical integration is discussed. In this computation the total estimated overhead is less than 10 per cent.     

Eye fixation patterns among dyslexic and normal readers: Effects of word length and word frequency.

Eye fixation patterns of 21 dyslexic and 21 younger nondyslexic readers were compared when they read aloud 2 texts. The study examined whether word-frequency and word-length effects previously found for skilled adult readers would generalize equally to younger dyslexic and nondyslexic readers. Significantly longer gaze durations and reinspection times were found for low-frequency and long words than for high-frequency and short words. The effects also showed up in the number of fixations on the target words. The effects did not differ significantly for the 2 experimental groups. The results run counter to the oculomotor dysfunction hypothesis of dyslexia. Instead, they support the view that both dyslexic and nondyslexic readers' eye fixation patterns reflect their difficulties in successfully identifying words in a text. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bayesian Model Learning Based on Predictive Entropy

Bayesian paradigm has been widely acknowledged as a coherent approach to learning putative probability model structures from a finite class of candidate models. Bayesian learning is based on measuring the predictive ability of a model in terms of the corresponding marginal data distribution, which equals the expectation of the likelihood with respect to a prior distribution for model parameters. The main controversy related to this learning method stems from the necessity of specifying proper prior distributions for all unknown parameters of a model, which ensures a complete determination of the marginal data distribution. Even for commonly used models, subjective priors may be difficult to specify precisely, and therefore, several automated learning procedures have been suggested in the literature. Here we introduce a novel Bayesian learning method based on the predictive entropy of a probability model, that can combine both subjective and objective probabilistic assessment of uncertain quantities in putative models. It is shown that our approach can avoid some of the limitations of the earlier suggested objective Bayesian methods.     

Approximability of identifying codes and locating-dominating codes

We study the approximability and inapproximability of finding identifying codes and locating-dominating codes of the minimum size. In general graphs, we show that it is possible to approximate both problems within a logarithmic factor, but sublogarithmic approximation ratios are intractable. In bounded-degree graphs, there is a trivial constant-factor approximation algorithm, but arbitrarily low approximation ratios remain intractable. In so-called local graphs, there is a polynomial-time approximation scheme. We also consider fractional packing of codes and a related problem of finding minimum-weight codes.     

Expression of ion transport-associated proteins in human efferent and epididymal ducts

Appropriate intraluminal microenvironment in the epididymis is essential for maturation of sperm. To clarify whether the anion transporters SLC26A2, SLC26A6, SLC26A7, and SLC26A8 might participate in generating this proper intraluminal milieu, we studied the localization of these proteins in the human efferent and the epididymal ducts by immunohistochemistry. In addition, immunohistochemistry of several SLC26-interacting proteins was performed: the Na(+)/H(+) exchanger 3 (NHE3), the Cl(-) channel cystic fibrosis transmembrane conductance regulator (CFTR), the proton pump V-ATPase, their regulator Na(+)/H(+) exchanger regulating factor 1 (NHERF-1), and carbonic anhydrase II (CAII). Our results show that SLC26A6, CFTR, NHE3, and NHERF-1 are co-expressed on the apical side of the nonciliated cells, and SLC26A2 appears in the cilia of the ciliated cells in the human efferent ducts. In the epididymal ducts, SLC26A6, CFTR, NHERF-1, CAII, and V-ATPase (B and E subunits) were co-localized to the apical mitochondria rich cells, while SLC26A7 was expressed in a subgroup of basal cells. SLC26A8 was not found in the structures studied. This is the first study describing the localization of SLC26A2, A6 and A7, and NHERF-1 in the efferent and the epididymal ducts. Immunolocalization of human CFTR, NHE3, CAII, and V-ATPase in these structures differs partly from previous reports from rodents. Our findings suggest roles for these proteins in male fertility, either independently or through interaction and reciprocal regulation with co-localized proteins shown to affect fertility, when disrupted.     

Investigation on the influence of various welding parameters on the arc thermal efficiency of the GTAW process by calorimetric method

Arc efficiency of Gas Tungsten Arc Welding (GTAW) was determined by calorimetric method. A water-cooled anode calorimeter was designed and manufactured to measure the arc thermal efficiency, which was determined as a function of current, arc length, polarity and gas flow rate for GTAW of mild steel. With Direct Current Electrode Negative (DCEN) polarity and 5 mm arc length, a thermal efficiency of 67±4% was obtained, which was independent of the welding current. With Direct Current Electrode Positive (DCEP) polarity and 5 mm arc length, arc thermal efficiency was determined as 52±4%. The experimental data show that the arc efficiency decreases from 67% to 58% and 51% as the arc length increases from 5 mm to 11 and 17.5 mm, respectively. The experimental results also show that the arc efficiency is not significantly affected by the shielding gas flow rate.     

Fatty acids of a whitefish (Coregonus albula) flesh lipids

Using gas chromatographic-mass spectrometric methods 50 fatty acid components of the flesh lipids of a fresh-water whitefish have been examined in detail. The total lipids represented, on average, 3.0% of the wet weight of whitefish fillets. Saturated, monoenoic and polyenoic fatty acids were present in proportions of 31.4, 22.4 and 44.2%, respectively. About half of the total saturated acids was composed of palmitic acid (16:0, 16.1 %), which is generally abundant in fish lipids. The proportion of saturated iso- and anteiso-acids was 2.9%. The major monoenoic acid was oleic acid (18:1,ω9 10.6%), whereas the monoenoic C₂₀-acids were present only in minor amounts and the monenoic C₂₂-acids were not detected at all. The polyenoic fatty acids were predominantly of ω3 series with docosahexaenoic (22:6ω3, 9.4%) and cicosapentaenoic (20:5ω3, 7.7%) acids as the major components. Linoleic (18:2ω6), linolenic (18:3ω3), octadecatetraenoic (18:4ω3) and arachidonic (20:4ω6) acids were also present in remarkable proportions each amounting to about 4.5% of the total fatty acids.     

Impact modification of lactic acid based poly(ester-urethanes) by blending

Branched biodegradable poly(ester-urethane)(PEU) was blended with two elastic biodegradable copolymers in proportions 5, 10, 15, and 20 wt % to investigate their effect on this hard and brittle polymer. Copolymer of L-lactide and ϵ-caprolactone, P(L-LA50/CL50), was synthesized by ring-opening polymerization and the other elastic poly(L-lactic acid-co-ϵ-caprolactone)urethane, P(LA50/CL50)U, was prepared by direct polycondensation of L-lactic acid and ϵ-caprolactone, followed with urethane bonding. In addition, four elastic biodegradable copolymers, three of them P(L-LA/CL) and one P(LA/CL)U, were blended with linear PEU to investigate their modifying effect on PEU. These compositions studied were 10, 15, and 20 wt % of P(L-LA40/CL60), P(L-LA60/CL40), P(L-LA80/CL20), and P(LA40/CL60)U in PEU. Blending was done in a batch mixer. PEU became more ductile when blended with P(L-LA/CL) and P(LA/CL)U, and its impact resistance improved markedly. In general, an addition of 15 wt % of copolymer appeared to give the most desirable mechanical properties. Moreover, the more L-lactide in the P(L-LA/CL) copolymer, the better was the miscibility of the blends, as shown by dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). One P(L-LA/CL) was also blended with poly(DL-lactide) (PDLLA) to see if the dispersion of rubbery copolymer particles was the same in PDLLA and PEU. A well-known commercial nonbiodegradable rubber [styrene/ethylene/butylene copolymer (SEBS)] was blended with linear PEU to compare its effect on impact strength. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1335–1343, 1997     

Lactic acid based poly(ester-urethanes): Use of hydroxyl terminated prepolymer in urethane synthesis

We studied a two step process for lactic acid polymerization: in the first step, the lactic acid is condensation polymerized to a low molecular weight hydroxyl terminated prepolymer and then the molecular weight is raised by joining prepolymer chains together using diisocyanate as the chain extender. The resulting polymer is a thermoplastic poly(ester-urethane). The polymer samples were carefully characterized with ¹³C-NMR, GPC, DSC, and IR. The results indicate that high conversions of lactic acid can be achieved, as well as independent control of the stereostructure, long chain branches, molecular weight average, and molecular weight distribution. Lactic acid is converted into a poly(ester-urethane) with a weight average molecular weight as high as 390,000 g/mol and a glass transition temperature of 53.7°C. The analyzed content of the monomer in the prepolymer is less than 1 mol % and the lactide content 2.4 mol %, while the final poly(ester-urethane) is essentially monomer and lactide free. The mechanical properties of the poly(ester-urethane) are comparable to those of polylactides. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1091–1100, 1997