Off-pump transapical mitral valve-in-ring implantation.

OBJECTIVES: The study aimed to evaluate the feasibility of off-pump transapical mitral valve-in-ring implantation and to test the performance of a custom-made self-expandable stent valve, in comparison with the standard SAPIEN valve. METHODS: Acute experiments were performed in five pigs. Animals (mean weight 58.4 ± 7.3 kg) underwent mitral valve annuloplasties under cardiopulmonary bypass using 26-mm rings (SJM?). Then, a 30-mm custom-made self-expandable stent valve or a 23-mm balloon-expandable transcatheter heart valve (Edwards SAPIEN XT?) was deployed within the annuloplasty rings through a transatrial access and under direct vision. Subsequently, the stent valves were inserted transapically under fluoroscopic guidance and off pump. RESULTS: The procedural success of transatrial and transapical mitral valve-in-ring procedures was 100% (10 of 10). Mean transatrial and transapical procedure time was 2.0 ± 1.1 and 22.0 ± 5.7 min, respectively. Haemodynamic status during transapical implantation remained stable, and differences in data collected before and after the stent-valve deployment were not statistically significant. Mean mitral annulus diameter and mean mitral orifice area in the group of self-expandable stent valves were 2.60 ± 0.02 cm and 4.16 ± 0.48 cm(2), respectively, whereas in the SAPIEN group they were 1.95 ± 0.18 cm and 2.26 ± 0.20 cm(2), respectively. Trace or mild regurgitation was detected only in the self-expandable stent-valve group. Mean gradients were 4.1 ± 4.5 mmHg across the self-expandable stent valves and 1.0 ± 0 mmHg across the SAPIEN valves. Postmortem examination confirmed adequate positioning of the self-expandable valves and the SAPIEN valves within the annuloplasty ring. CONCLUSIONS: Off-pump transapical mitral valve-in-ring implantation is safe and feasible. Transapical access may represent the ideal option for valve-in-ring procedures in cases of recurrent mitral regurgitation after mitral valve repair, in high-risk patients. Owing to the supra-annular profile of the valve components, our custom-made nitinol stent valve provides nearer to normal functional area than the SAPIEN valve.

Brownian pump powered by a white-noise flasing ratchet

A Brownian pump of particles powered by a stochastic flashing ratchet mechanism is studied. The pumping device is embedded in a finite region and bounded by particle reservoirs. In the steady state, we exactly calculate the spatial density profile, the concentration ratio between both reservoirs and the particle flux. We propose a simulation framework for the consistent evaluation of such observable quantities.

Stabilization of soil hydraulic properties under a long term no-till system

The area under the no-tillage system (NT) has been increasing over the last few years. Some authors indicate that stabilization of soil physical properties is reached after some years under NT while other authors debate this. The objective of this study was to determine the effect of the last crop in the rotation sequence (1st year: maize, 2nd year: soybean, 3rd year: wheat/soybean) on soil pore configuration and hydraulic properties in two different soils (site 1: loam, site 2: sandy loam) from the Argentinean Pampas region under long-term NT treatments in order to determine if stabilization of soil physical properties is reached apart from a specific time in the crop sequence. In addition, we compared two procedures for evaluating water-conducting macroporosities, and evaluated the efficiency of the pedotransfer function ROSETTA in estimating the parameters of the van Genuchten-Mualem (VGM) model in these soils. Soil pore configuration and hydraulic properties were not stable and changed according to the crop sequence and the last crop grown in both sites. For both sites, saturated hydraulic conductivity, K0, water-conducting macroporosity, εma, and flow-weighted mean pore radius, R0ma, increased from the 1st to the 2nd year of the crop sequence, and this was attributed to the creation of water-conducting macropores by the maize roots. The VGM model adequately described the water retention curve (WRC) for these soils, but not the hydraulic conductivity (K) vs tension (h) curve. The ROSETTA function failed in the estimation of these parameters. In summary, mean values of K0 ranged from 0.74 to 3.88 cm h-1. In studies on NT effects on soil physical properties, the crop effect must be considered.

Physical-hydraulic properties of a sandy loam typic paleudalf soil under organic cultivation of 'montenegrina' mandarin (Citrus deliciosa Tenore)¹

Citrus plants are the most important fruit species in the world, with emphasis to oranges, mandarins and lemons. In Rio Grande do Sul, Brazil, most fruit production is found on small properties under organic cultivation. Soil compaction is one of the factors limiting production and due to the fixed row placement of this crop, compaction can arise in various manners in the interrows of the orchard. The aim of this study was to evaluate soil physical properties and water infiltration capacity in response to interrow management in an orchard of mandarin (Citrus deliciosa Tenore 'Montenegrina') under organic cultivation. Interrow management was performed through harrowing, logs in em "V", mowing, and cutting/knocking down plants with a knife roller. Soil physical properties were evaluated in the wheel tracks of the tractor (WT), between the wheel tracks (BWT), and in the area under the line projection of the canopy (CLP), with undisturbed soil samples collected in the 0.00-0.15, 0.15-0.30, 0.30-0.45, and 0.45-0.60 m layers, with four replicates. The soil water infiltration test was performed using the concentric cylinder method, with a maximum time of 90 min for each test. In general, soil analysis showed a variation in the physical-hydraulic properties of the Argissolo Vermelho-Amarelo distrófico arênico (sandy loam Typic Paleudalf) in the three sampling sites in all layers, regardless of the management procedure in the interrows. Machinery traffic leads to heterogeneity in the soil physical-hydraulic properties in the interrows of the orchard. Soil porosity and bulk density are affected especially in the wheel tracks of the tractor (WT), which causes a reduction in the constant rate of infiltration and in the accumulated infiltration of water in this sampling site. The use of the disk harrow and mower leads to greater harmful effects on the soil, which can interfere with mandarin production.

Postmortem pump-driven reperfusion of the vascular system of porcine lungs: towards a new model for surgical training.

PURPOSE: The objective of this experiment is to establish a continuous postmortem circulation in the vascular system of porcine lungs and to evaluate the pulmonary distribution of the perfusate. This research is performed in the bigger scope of a revascularization project of Thiel embalmed specimens. This technique enables teaching anatomy, practicing surgical procedures and doing research under lifelike circumstances. METHODS: After cannulation of the pulmonary trunk and the left atrium, the vascular system was flushed with paraffinum perliquidum (PP) through a heart-lung machine. A continuous circulation was then established using red PP, during which perfusion parameters were measured. The distribution of contrast-containing PP in the pulmonary circulation was visualized on computed tomography. Finally, the amount of leak from the vascular system was calculated. RESULTS: A reperfusion of the vascular system was initiated for 37 min. The flow rate ranged between 80 and 130 ml/min throughout the experiment with acceptable perfusion pressures (range: 37-78 mm Hg). Computed tomography imaging and 3D reconstruction revealed a diffuse vascular distribution of PP and a decreasing vascularization ratio in cranial direction. A self-limiting leak (i.e. 66.8% of the circulating volume) towards the tracheobronchial tree due to vessel rupture was also measured. CONCLUSIONS: PP enables circulation in an isolated porcine lung model with an acceptable pressure-flow relationship resulting in an excellent recruitment of the vascular system. Despite these promising results, rupture of vessel walls may cause leaks. Further exploration of the perfusion capacities of PP in other organs is necessary. Eventually, this could lead to the development of reperfused Thiel embalmed human bodies, which have several applications.

Multiplan Spreadsheets for Highway and Hydraulic Engineering Computations in County Engineering Offices, HR-284, 1987

Multiplan spreadsheet solutions were developed for a set of hydraulic and highway engineering computations of common interest to county engineers. These include earthwork, vertical and horizontal curves, staking superelevated curves and sign inventories for highways. The hydraulic applications were ditch flow, runoff, culvert size and stage discharge.

Estimating vadose zone hydraulic properties using ground penetrating radar: The impact of prior information

A number of geophysical methods, such as ground-penetrating radar (GPR), have the potential to provide valuable information on hydrological properties in the unsaturated zone. In particular, the stochastic inversion of such data within a coupled geophysical-hydrological framework may allow for the effective estimation of vadose zone hydraulic parameters and their corresponding uncertainties. A critical issue in stochastic inversion is choosing prior parameter probability distributions from which potential model configurations are drawn and tested against observed data. A well chosen prior should reflect as honestly as possible the initial state of knowledge regarding the parameters and be neither overly specific nor too conservative. In a Bayesian context, combining the prior with available data yields a posterior state of knowledge about the parameters, which can then be used statistically for predictions and risk assessment. Here we investigate the influence of prior information regarding the van Genuchten-Mualem (VGM) parameters, which describe vadose zone hydraulic properties, on the stochastic inversion of crosshole GPR data collected under steady state, natural-loading conditions. We do this using a Bayesian Markov chain Monte Carlo (MCMC) inversion approach, considering first noninformative uniform prior distributions and then more informative priors derived from soil property databases. For the informative priors, we further explore the effect of including information regarding parameter correlation. Analysis of both synthetic and field data indicates that the geophysical data alone contain valuable information regarding the VGM parameters. However, significantly better results are obtained when we combine these data with a realistic, informative prior.

Acid inhibition on the first day of dosing : comparison of four proton pump inhibitors

RESUME Introduction: Les inhibiteurs de la pompe à protons sont actuellement considérés comme les médicaments de choix pour le traitement des affections peptiques comme l'ulcère gastroduodénal et l'oesophagite de reflux. La rapidité, ainsi que le degré d'inhibition de la sécrétion gastrique acide sont importants pour le contrôle optimal des symptômes ainsi que pour le traitement de ces affections. But : Le but principal de cette étude a été de comparer, chez les sujets asymptomatiques non infectés par H. pylori, par pH-métrie intragastrique de 24 heures, la rapidité et la durée de l'action antisécrétoire de doses uniques de rabéprazole 20 mg, d'oméprazole capsule 20 mg, d'oméprazole en comprimé MUPS (« Multiple Unit Pellet System ») 20 mg, de pantoprazole 40 mg et de lansoprazole 30 mg, respectivement. Matériel et méthodes : Cette étude, effectuée en double aveugle et randomisée, a été conduite de manière croisée chez 18 sujets H. pylori-négatifs. Une pH-métrie de 24 heures a été effectuée le jour de l'administration du médicament (dose unique de rabéprazole 20 mg, de lansoprazole 30mg, de pantoprazole 40 mg, d'oméprazole capsule 20 mg, d'oméprazole MUPS comprimé 20mg, ou de placebo). Résultats : Le pH intragastrique médian (3.4 vs. 2.9, 2.2, 1.9 et 1.8, respectivement; p≤ 0.03) et le temps avec un pH supérieur à 4 pendant les 24 heures suivant la prise du médicament (8.0 heures vs. 7.4, 4.9, 2.9, et 3.0, respectivement; p≤ 0.003) ont été statistiquement plus élevés avec le rabéprazole qu'avec le lansoprazole, le pantoprazole, l'oméprazole capsule, l'oméprazole comprimé MUPS, ou le placebo. Les valeurs du pH pendant les périodes diurnes et nocturnes étaient plus hautes avec le rabeprazole et le lansoprazole qu'avec le pantoprazole, l'oméprazole capsule, et l'oméprazole comprimé MUPS (p≤0.04). Conclusion : Le rabéprazole s'est montré le plus efficace de tous les inhibiteurs de pompe à protons étudiés durant le premier jour de l'administration du médicament. SUMMARY Background: Rapid and consistent acid suppression on the first day of dosing may be important in treating acid-related disorders. Aim: To compare the antisecretory activity and onset of action of single doses of rabeprazole, lansoprazole, pantoprazole, omeprazole capsule, omeprazole multiple unit pellet system (MUPS) tablet and placebo in healthy Helicobacter pylori-negative subjects. Methods: This cross-over, double-blind, randomized study was performed in 18 H. pylori-negative subjects. Twenty-four-hour intragastric pH monitoring was performed on the day of treatment (once-daily dose of rabeprazole 20 mg, lansoprazole 30 mg, pantoprazole 40 mg, omeprazole capsule 20 mg, omeprazole MUPS tablet 20 mg or placebo). Results: The intragastric pH (3.4) and time at pH > 4 during the 24 h post-dose (8.0 h) were significantly greater with rabeprazole than with lansoprazole, pantoprazole, omeprazole capsule, omeprazole MUPS tablet or placebo (P ≤ 0.04 for rabeprazole vs. the others). Daytime and night-time pH values were higher with rabeprazole and lansoprazole than with pantoprazole, omeprazole capsule and omeprazole MUPS tablet (P ≤ 0.04). Conclusion: Rabeprazole was the most potent acid inhibitor of all the proton pump inhibitors tested during the first day of dosing.

A combined infrared/heat pump drying technology applied to a rotary dryer

Selostus: Yrttien ja vihannesten infrapunakuivaus rumpukuivurissa

Bayesian-MCMC inversion of time-lapse geophysical data to characterize vadose zone hydraulic behaviour

Geophysical methods have the potential to provide valuable information on hydrological properties in the unsaturated zone. In particular, time-lapse geophysical data, when coupled with a hydrological model and inverted stochastically, may allow for the effective estimation of subsurface hydraulic parameters and their corresponding uncertainties. In this study, we use a Bayesian Markov-chain-Monte-Carlo (MCMC) inversion approach to investigate how much information regarding vadose zone hydraulic properties can be retrieved from time-lapse crosshole GPR data collected at the Arrenaes field site in Denmark during a forced infiltration experiment.

Impact of controlled changes in grain size and pore space characteristics on the hydraulic conductivity and spectral induced polarization response of "proxies" of saturated alluvial sediments

Understanding the influence of pore space characteristics on the hydraulic conductivity and spectral induced polarization (SIP) response is critical for establishing relationships between the electrical and hydrological properties of surficial unconsolidated sedimentary deposits, which host the bulk of the world's readily accessible groundwater resources. Here, we present the results of laboratory SIP measurements on industrial-grade, saturated quartz samples with granulometric characteristics ranging from fine sand to fine gravel, which can be regarded as proxies for widespread alluvial deposits. We altered the pore space characteristics by changing (i) the grain size spectra, (ii) the degree of compaction, and (iii) the level of sorting. We then examined how these changes affect the SIP response, the hydraulic conductivity, and the specific surface area of the considered samples. In general, the results indicate a clear connection between the SIP response and the granulometric as well as pore space characteristics. In particular, we observe a systematic correlation between the hydraulic conductivity and the relaxation time of the Cole-Cole model describing the observed SIP effect for the entire range of considered grain sizes. The results do, however, also indicate that the detailed nature of these relations depends strongly on variations in the pore space characteristics, such as, for example, the degree of compaction. The results of this study underline the complexity of the origin of the SIP signal as well as the difficulty to relate it to a single structural factor of a studied sample, and hence raise some fundamental questions with regard to the practical use of SIP measurements as site- and/or sample-independent predictors of the hydraulic conductivity.

Is our heart a well-designed pump? The heart along animal evolution.

A carrier system for gases and nutrients became mandatory when primitive animals grew larger and developed different organs. The first circulatory systems are peristaltic tubes pushing slowly the haemolymph into an open vascular tree without capillaries (worms). Arthropods developed contractile bulges on the abdominal aorta assisted by accessory hearts for wings or legs and by abdominal respiratory motions. Two-chamber heart (atrium and ventricle) appeared among mollusks. Vertebrates have a multi-chamber heart and a closed circulation with capillaries. Their heart has two chambers in fishes, three chambers (two atria and one ventricle) in amphibians and reptiles, and four chambers in birds and mammals. The ventricle of reptiles is partially divided in two cavities by an interventricular septum, leaving only a communication of variable size leading to a variable shunt. Blood pressure increases progressively from 15 mmHg (worms) to 170/70 mmHg (birds) according to the increase in metabolic rate. When systemic pressure exceeds 50 mmHg, a lower pressure system appears for the circulation through gills or lungs in order to improve gas exchange. A four-chamber heart allows a complete separation of systemic and pulmonary circuits. This review describes the circulatory pumping systems used in the different classes of animals, their advantages and failures, and the way they have been modified with evolution.