132 research outputs found

    Morphometry and topography of the coronary ostia in the European bison

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    Background: Coronary vessels have been widely studied in many species of domestic and wild mammals. However, there are no available literature reports describing the morphology and morphometry of the coronary ostia of the European bison (Bison bonasus). The aim of this study was to measure the area of the coronary ostia and assess their localisation in the coronary sinuses of the aortic root in the European bison. Materials and methods: The study material comprised 27 hearts from European bison of both sexes (16 males and 11 females), from 3 months to 26 years old, inhabiting the Bialowieza Forest (Bialowieza National Park, Poland). The animals were divided into two age groups: ≤ 5 years (group I) and > 5 years (group II). Results: In all the studied European bison, the aortic valve consisted of three semilunar leaflets, left, right and septal. The ostia of both coronary arteries were located beneath the sinotubular junction. The dimensions of the left coronary ostium were larger than those of the right coronary ostium. They were longer by on average 4.5 mm (95% confidence interval [CI] 3.5–5.6 mm), they were wider by on average 1.6 mm (95% CI 1.0–2.2 mm) and they had a larger area by on average 31.6 mm2 (95% CI 22.7–40.5 mm2). This was evident both in young and in adult bison. After adjusting for age, there were no differences in the ostia dimensions between males and females. There were no differences in the structure of the left and right coronary arteries in nine animals. In the remaining 18 animals, there were variations in the morphology of the coronary ostia or additional ostia. Conclusions: Because of the anatomical similarity between the European bison and other ruminants, the results of this study can be applied to the other species including endangered ones

    Quality and quantity comparison study of corrosion casts of bovine testis made using two synthetic kits: Plastogen G and Batson no. 17

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    Background: Although corrosion casting has been implemented for almost five centuries, the choice of resin has a strong influence on the effectiveness of casting vessel formations. Our aim was to compare quality and quantity features of two groups of corrosion casts made using two kits: Plastogen G resin and Batson no. 17 resin. Materials and methods: Thirty corrosion casts were made of testicular arterial vessels (15 made using Plastogen G and 15 made using Batson no. 17) and their shape, colour, fragility and flexibility were evaluated. The following parameters were measured: maximal width of corrosion cast of testis, maximal length of centripetal and centrifugal arteries, diameter of testicular artery and its terminal branches. Based on these measurements, five indexes were calculated (Iq1–Iq5). Results: Generally both groups of corrosion casts demonstrated similar attributes. Only the rami tunicales minores displayed higher fragility and lower flexibility in the Plastogen G group than the Batson no. 17 group. The only observed quantitative difference was that Iq3 was significantly lower in the Plastogen G group (0.71 ± 0.01) than in Batson no. 17 group (0.79 ± 0.01; p = 0.0092). Conclusions: The two corrosion cast groups displayed similar qualitative and quantitative attributes. Batson no. 17 appears to be a good resin for three-dimensional visualisation of extra- and intratesticular arterial vessels

    THE NAS PARALLEL BENCHMARKS

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    The Numerical Aerodynamic Simulation (NAS) Program, which is based at NASA Ames Research Center, is a large-scale effort to advance the state of computational aerodynamics. Specifically, the NAS organization aims &dquo;to provide the Nation’s aerospace research and development community by the year 2000 a highperformance, operational computing system capable of simulating an entire aerospace vehicle system within a computing time of one to several hours&dquo; (NAS Systems Division, 1988, p. 3). The successful solution of this &dquo;grand challenge&dquo; problem will require the development of computer systems that can perform the required complex scientific computations at a sustained rate nearly 1,000 times greater than current generation supercomputers can achieve. The architecture of computer systems able to achieve this level of performance will likely be dissimilar to the shared memory multiprocessing supercomputers of today. While no consensus yet exists on what the design will be, it is likely that the system will consist of at least 1,000 processors computing in parallel. Highly parallel systems with computing power roughly equivalent to that of traditional shared memory multiprocessors exist today. Unfortunately, for various reasons, the performance evaluation of these systems on comparable types of scientific computations is very difficult. Relevant data for the performance of algorithms of interest to the computational aerophysics community on many currently available parallel systems are limited. Benchmarking and performance evaluation of such systems have not kept pace with advances in hardware, software, and algorithms. In particular, there is as yet no generally accepted benchmark program or even a benchmark strategy for these systems

    Radiation Sterilization of Anthracycline Antibiotics in Solid State

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    The impact of ionizing radiation generated by a beam of electrons of 25–400 kGy on the stability of such analogs of anthracycline antibiotics as daunorubicin (DAU), doxorubicin (DOX), and epidoxorubicin (EPI) was studied. Based on EPR results, it was established that unstable free radicals decay exponentially with the half-time of 4 days in DAU and DOX and 7 days in EPI after irradiation. Radiation-induced structural changes were analyzed with the use of spectrophotometric methods (UV-Vis and IR) and electron microscope imaging (SEM). A chromatographic method (HPLC-DAD) was applied to assess changes in the contents of the analogs in the presence of their impurities. The study showed that the structures of the analogs did not demonstrate any significant alterations at the end of the period necessary for the elimination of unstable free radicals. The separation of main substances and related substances (impurities and potential degradation products) allowed determining that no statistically significant changes in the content of particular active substances occurred and that their conversion due to the presence of free radicals resulting from exposure to an irradiation of 25 kGy (prescribed to ensure sterility) was not observed

    A time-frequency analysis approach for condition monitoring of a wind turbine gearbox under varying load conditions

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    This paper deals with the condition monitoring of wind turbine gearboxes under varying operating conditions. Generally, gearbox systems include nonlinearities so a simplified nonlinear gear model is developed, on which the time–frequency analysis method proposed is first applied for the easiest understanding of the challenges faced. The effect of varying loads is examined in the simulations and later on in real wind turbine gearbox experimental data. The Empirical Mode Decomposition (EMD) method is used to decompose the vibration signals into meaningful signal components associated with specific frequency bands of the signal. The mode mixing problem of the EMD is examined in the simulation part and the results in that part of the paper suggest that further research might be of interest in condition monitoring terms. For the amplitude–frequency demodulation of the signal components produced, the Hilbert Transform (HT) is used as a standard method. In addition, the Teager–Kaiser energy operator (TKEO), combined with an energy separation algorithm, is a recent alternative method, the performance of which is tested in the paper too. The results show that the TKEO approach is a promising alternative to the HT, since it can improve the estimation of the instantaneous spectral characteristics of the vibration data under certain conditions

    Preliminary effects of fertilization on ecochemical soil condition in mature spruce stands experiencing dieback in the Beskid Śla̧ski and Żywiecki Mountains, Poland

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    In recent years, there has been the phenomena of spruce dieback in Europe. Significant areas of spruce low mortality now cover both sides of the Polish southern border. We evaluated ecochemical parameters influencing the heavy dieback occurring in mature spruce stands in the Polish Carpathian Mountains. Dolomite, magnesite and serpentinite fertilizers were applied to experimental plots located in 100-year-old stands in the autumn of 2008. The experimental plots were located in the mid-elevational forest zone (900-950 m) on two nappes of the flysch Carpathians: Magura (Ujsoły Forest District) and Silesian (Wisła Forest District). The saturation of the studied soils demonstrates moderate resilience of soils in Wisła Forest District in relation to acid load and high flexibility of the Ujsoły soils. After application of the fertilizers, an increase of Mg, Ca and Mb was noted in the soil solution, determined in the overlaying highly acidic organic horizons through the ion-exchange buffering mechanism of highly protonated functional groups with high buffering capacity. Magnesium concentration increased following fertilization, presenting a potential improvement of forest growth capacity without the hazard of adverse side effects of liming. Aluminium stress in old spruce is unlikely, while trees in the control plots in Wisła Forest District may already be sensitive to aluminium stress. Serpentinite fertilization improved the supply of soils in magnesium without causing significant changes in the pH of the soil. Such changes in the pH were found in dolomite and magnesite fertilizer. © The Author(s) 2014

    Bearing signal separation enhancement with application to helicopter transmission system

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    The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Bearing vibration signal separation is essential for fault detection of gearboxes, especially where the vibration is nonstationary, susceptible to background noise, and subjected to an arduous transmission path from the source to the receiver. This paper presents a methodology for improving fault detection via a series of vibration signal processing techniques, including signal separation, synchronous averaging (SA), spectral kurtosis (SK), and envelope analysis. These techniques have been tested on experimentally obtained vibration data acquired from the transmission system of a CS-29 Category A helicopter gearbox operating under different bearing damage conditions. Results showed successful enhancement of bearing fault detection on the second planetary stage of the gearbo

    Tension pneumothorax in a newborn after Cesarean-section delivery -A case report-

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    Tension pneumothorax in newborns is a rare but life-threatening complication. We encountered a case of a full-term neonate with a breech presentation. An elective cesarean section was scheduled. Immediately after delivery, the newborn was found to be breathless with a heart rate <60/min. During intubation and cardiac massage, the patient's femoral artery and vein were accessed. The infantogram revealed a right side tension pneumothorax. A 22 gauge needle thoracentesis relieved the right side chest pressure and a closed thoracostomy was performed. The severe acidosis was corrected with sodium bicarbonate. The patient was managed in the neonatal intensive care unit, but died from uncorrectable acidosis. We report this case with a review of the relevant literature
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