On stationarity of Lagrangian observations of passive tracer velocity in a compressible environment

We study the transport of a passive tracer particle in a steady strongly mixing flow with a nonzero mean velocity. We show that there exists a probability measure under which the particle Lagrangian velocity process is stationary. This measure is absolutely continuous with respect to the underlying probability measure for the Eulerian flow.Comment: Published at http://dx.doi.org/10.1214/105051604000000945 in the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Web Pages Content Analysis Using Browser-Based Volunteer Computing

Existing solutions to the problem of finding valuable information on the Websuffers from several limitations like simplified query languages, out-of-date in-formation or arbitrary results sorting. In this paper a different approach to thisproblem is described. It is based on the idea of distributed processing of Webpages content. To provide sufficient performance, the idea of browser-basedvolunteer computing is utilized, which requires the implementation of text pro-cessing algorithms in JavaScript. In this paper the architecture of Web pagescontent analysis system is presented, details concerning the implementation ofthe system and the text processing algorithms are described and test resultsare provided

Left ventricle systolic volume in vasovagal syncope patients

One of the hypotheses put forward concerning the mechanism of vasovagal syncope is that the vagal afferent fibres are activated during vigorous contractions against a partly empty left ventricle. The aim of the study was to confirm this hypothesis by using 2D echocardiography during a head-up tilt test. The study was carried out on 39 patients (17 male, 22 female, age range 21–64 years), all with a history of recurrent syncope. The patients were examined using a 2D echo to measure the end-diastolic and end-systolic volume before the head-up tilt test after the Westminster protocol (45min/60 grade) and every five minutes after tilting. T patients during head-up tilt test had a positive response and 32 proved negative. A reduction of both the end-diastolic and end-systolic volumes of the left ventricle was noticed. There was no significant difference in the degree of ejection fraction reduction. The difference in ejection fraction reduction between the two groups was similarly non-significant. It was also noticed that the patients with a positive response had more vigorous contractions than those with a negative test. The decision was therefore taken to use a different parameter for the left ventricle contraction, namely the LV posterior wall slope. As this parameter is partly dependent on time, its use in confirming the extremely vigorous nature of the contractions was considered appropriate. Only 6 patients were tested using this parameter. A tendency towards greater left ventricle posterior wall slope values, both before and during tilting was noticed in the group of patients with vasovagal reaction. Our data shows that vigorous contraction is probably less responsible for vasovagal syncope release than left ventricle volume reduction

Anterior region of the atrioventricular perinodal area in relation to radiofrequency ablation procedures

Atrioventricular nodal reentry tachycardia base on reentry circulation in nodal-perinodal area. The radical treatment of choice is radiofrequency ablation. Procedure approached from the anterior-superior (fast) region sufficient a few seconds of energy delivery for success, however this can result in A-V block. The possibility that arrhythmias substrate may lie very superficially (success of ablation) and damage the normal structures (complication) in the perinodal region must be considered. In order to confirm this hypothesis we examined the autopsy material of 100 normal hearts, both sexes from 18 to 105 years of age (control) and 50 hearts with A-V total block 45-95 years of age (block). We paid attention to the morphology of the nodal artery (NA), atrial inputs (AI) and transitional inputs (TI). It was observed that NA at the level of the central fibrous body was positioned in 94% in the central and in 6% in the inferior part of Koch&#8217;s triangle. It was removed from the endocardium 3-6 mm in control and 2-5 mm in block group respectively (NS). In the perinodal area we distinguished AI that directly joined the A-V compact node: superficial (right part of the interatrial septum) or deep (left part). The former occurred in 100% of controls and in 80% of block groups (NS), and the latter in 80% of control group and in 34% in block respectively (p < 0.05). The real substrate of arrhythmia in anterior-superior region lies very superficially and far from the conduction tissue; NA in examined hearts was lying deep beneath the endocardium; ablation close to the node could result in A-V block

Volunteer Computing Simulation Using Repast And Mason

Volunteer environments usually consist of a large number of computing nodes,with highly dynamic characteristics, therefore reliable models for a planning ofthe whole computing are highly desired. An easy to implement approach to mo-delling and simulation of such environments may employ agent-based universalsimulation frameworks, such as RePast or MASON. In the course of the paperthe above-mentioned simulation frameworks are adapted to support simulationof volunteer computing. After giving implementation details, selected resultsconcerning computing time and speedup are given and are compared with theones obtained from an actual volunteer environment

RADIal versus femoral approach for percutaneous coronary interventions in patients with Acute Myocardial Infarction (RADIAMI): A prospective, randomized, single-center clinical trial

Background: The transradial approach for percutaneous coronary intervention (PCI) seems to be superior to transfemoral. The safety and efficacy of transradial approach for PCI in acute myocardial infarction is not well-established. Methods: Hundred patients with acute myocardial infarction qualified to PCI were randomly assigned to transradial (group I; n = 50) and transfemoral (group II; n = 50) approaches. Results: PCI was successful for almost all patients, except one from group II. There were no significant differences between groups in X-ray exposition, volume of contrast and total procedure duration. Small but significant elongation of door to stent time in group I was caused mostly by a longer time between beginning of procedure and arterial sheath introduction. Major bleeding complications occurred in three patients from group I and seven from group II. There were no significant differences observed between the two groups. Time to ambulation in group I was significantly shorter then in group II (22.6 &#177; 10.3 h vs. 34.7 &#177; 34.6 h; p = 0.003). Conclusions: The transradial approach for PCI in acute myocardial infarction has the same efficacy as transfemoral. There are no differences in total procedure duration, X-ray exposition or volume of contrast between the two approaches. A longer time from the patient&#8217;s admission to the individual stages of the PCI procedure in group I was mostly due to the longer times of the initial stages of the procedure. The use of transradial approach reduces the time to ambulation and allows rehabilitation to begin sooner. In both groups, bleeding complications occurred rarely

A Window into the Early–Middle Stone Age Transition in Northeastern Africa—A Marine Isotope Stage 7a/6 Late Acheulean Horizon from the EDAR 135 Site, Eastern Sahara (Sudan)

This paper presents the results of the analysis of a late Acheulean horizon from the EDAR 135 site, which was discovered in the Eastern Desert, Sudan, in an area heavily transformed by modern mining activity. A lithic assemblage was discovered there, within a layer of gravel sediments formed by a paleostream in a humid period of the Middle Pleistocene. This layer is OSL dated between 220 ± 12 and 145 ± 20 ka (MIS 7a/6). These dates indicate that the assemblage could be the youngest trace of the Acheulean in northeastern Africa. Technological analysis of the lithics reveals different core reduction strategies, including not only ad hoc ones based on multiplatform cores, but also discoidal and prepared cores. The use of prepared core reduction methods has already been confirmed at other Late Acheulean sites in Africa and the Middle East. Microwear traces observed on lithic artifacts could relate to on-site butchering activities

Kliniczno-echokardiograficzna ocena niedomykalności zastawki trójdzielnej u pacjentów ze stałą stymulacją serca

Wstęp: Wśród negatywnych konsekwencji stałej stymulacji serca związanych z obecnością wszczepionej elektrody wymienia się niedomykalność zastawki trójdzielnej. Jednakże brak wiarygodnych dowodów na poparcie tej tezy. Materiał i metody: Badaniem objęto grupę 124 pacjentów (69 mężczyzn i 55 kobiet) w wieku 16-93 lat (śr. 64,2 &plusmn; 15,2 roku). Chorych podzielono na 2 grupy: I (badaną) - pacjenci z implantowaną na stałe elektrodą komorową oraz II (kontrolną) - osoby bez elektrody w prawej komorze serca. U wszystkich chorych w badaniu przedmiotowym i podmiotowym zwracano szczególną uwagę na objawy wynikające z niedomykalności trójdzielnej. Rozpoznanie niedomykalności trójdzielnej ustalano na podstawie parametrów echokardiograficznych w badaniu dopplerowskim: zasięg i pole powierzchni fali zwrotnej, szerokość żyły głównej dolnej oraz obecność skurczowego przepływu wstecznego w żyle głównej dolnej i żyłach wątrobowych. Wyniki: Zaawansowanie niewydolności serca według klasyfikacji NYHA ustalone na podstawie całości obrazu klinicznego nie różniło się między grupami. Występowanie typowego szmeru niedomykalności trójdzielnej stwierdzono u 30% chorych z grupy I oraz u 3,6% z grupy II (p < 0,05). Na podstawie przyjętych parametrów oceny echokardiograficznej wykazano obecność niedomykalności zastawki trójdzielnej u 60 osób (75%) z grupy I oraz u 10 (32%) z grupy II (p < 0,05). Obecność niedomykalności trójdzielnej co najmniej II stopnia (tj. uznanej za istotną) stwierdzono częściej w grupie chorych z wszczepioną elektrodą komorową (47%) niż w grupie kontrolnej (16,1%) (p < 0,05). Podczas oceny zasięgu fali zwrotnej w badaniu dopplerowskim kodowanym kolorem wykazano statystycznie znamienną zależność od czasu, który upłynął od momentu wszczepienia elektrody do badania (p < 0,03). Nie obserwowano istotnych różnic w nasileniu niedomykalności w czasie własnego rytmu komór w porównaniu z rytmem wymuszonym przez stymulator: zasięg fali zwrotnej: 1,77 &plusmn; 1,99 vs. 1,52 &plusmn; &plusmn; 1,28 cm (p = 0,17); pole powierzchni fali zwrotnej: 1,71 &plusmn; 2,26 vs. 1,11 &plusmn; 1,13 cm2 (p = 0,35); szerokość żyły głównej dolnej: 1,99 &plusmn; 0,45 vs. 1,92 &plusmn; 0,43 cm (p = 0,35). Wnioski: Obecność elektrody w ujściu przedsionkowo-komorowym prawym na stałe wywołuje niedomykalność zastawki. Czynnikiem zwiększającym stopień regurgitacji jest czas od wszczepienia elektrody. Stymulowany rytm komór nie wpływa na obecność i nasilenie fali zwrotnej trójdzielnej. (Folia Cardiol. 2004; 11: 751&#8211;763