Predicting Transition from Laminar to Turbulent Flow over a Surface

A prediction of whether a point on a computer-generated surface is adjacent to laminar or turbulent flow is made using a transition prediction technique. A plurality of boundary-layer properties at the point are obtained from a steady-state solution of a fluid flow in a region adjacent to the point. A plurality of instability modes are obtained, each defined by one or more mode parameters. A vector of regressor weights is obtained for the known instability growth rates in a training dataset. For each instability mode in the plurality of instability modes, a covariance vector is determined, which is the covariance of a predicted local growth rate with the known instability growth rates. Each covariance vector is used with the vector of regressor weights to determine a predicted local growth rate at the point. Based on the predicted local growth rates, an n-factor envelope at the point is determined

Generating Inviscid and Viscous Fluid-Flow Simulations over an Aircraft Surface Using a Fluid-Flow Mesh

Fluid-flow simulation over a computer-generated aircraft surface is generated using inviscid and viscous simulations. A fluid-flow mesh of fluid cells is obtained. At least one inviscid fluid property for the fluid cells is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. A set of intersecting fluid cells that intersects the aircraft surface are identified. One surface mesh polygon of the surface mesh is identified for each intersecting fluid cell. A boundary-layer prediction point for each identified surface mesh polygon is determined. At least one boundary-layer fluid property for each boundary-layer prediction point is determined using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects. At least one updated fluid property for at least one fluid cell is determined using the at least one boundary-layer fluid property and the inviscid fluid simulation

Akute Epididymitis: Chronifizierung, Rezidive und Langzeitauswirkungen auf die Fertilität

Die akute Epididymitis, meist durch sexuell übertragbare Erreger oder uropathogene Keime verursacht, ist ein häufig auftretendes Krankheitsbild in der Urologie. Der akute Verlauf geht nicht nur mit starken Schmerzen und enormem Krankheitsgefühl einher, sondern auch mögliche Spätfolgen (Rezidive, Chronifizierung, Infertilität) können Auswirkungen auf die physische und psychische Gesundheit der Patienten haben. Bisher wurden die Folgen der akuten Epididymitis jedoch nicht umfassend untersucht. Für die vorliegende Arbeit erfolgte die Rekrutierung von 228 Patienten (Altersmedian 53 Jahre), die sich zwischen 2007 und 2013 in der urologischen Ambulanz der Uniklinik Gießen mit akuter Epididymitis vorgestellt hatten. Bei Studienbeginn lag die Nebenhodenentzündung mindestens 12 Monate zurück. Es gelang, von 154 Männern den Verlauf der Erkrankung durch den Fragebogen Probleme und Beschwerden nach der Nebenhodenentzündung zu erfassen. Zusätzlich füllten 120 Patienten den Fragebogen Chronic Epididmitis Symptom Index aus. In der Nachuntersuchung wurden Spermiogrammbefunde von 21 Patienten (medianes Follow-Up 61 Monate) erstellt und zusätzlich Blutproben zur Bestimmung der Sexualhormone FSH, LH, freies und Gesamttestosteron genommen. Zur Beurteilung der Fertilität wurden als Surrogatparameter vor allem die Basisparameter Spermatozoenkonzentration, Progressivmotilität und der Anteil normalgeformter Spermatozoen im Ejakulat herangezogen. Aber auch die Funktion von Prostata, Nebenhoden und Bläschendrüse wurde anhand biochemischer Parameter beurteilt. Zusätzlich erfolgte der Nachweis der Inflammationsparameter Granulozyten-Elastase und Peroxidase positive Leukozyten im Ejakulat. Für alle Parameter erfolgte ein Vergleich mit den erhobenen Befunden an Tag 14 und Tag 84 nach akuter Epididymitis. Aufgrund der relativ kleinen Stichprobengröße von 21 Patienten (Gruppe des Langzeit-Follow-Up) erfolgte zusätzlich der Vergleich der bereits vorhandenen Befunde aller rekrutierten Patienten (Gruppe des Kurzzeit-Follow-Up). Ferner wurden Fertilität und eingetretene Schwangerschaften nach akuter Epididymitis erfasst. In der vorliegenden Arbeit konnte gezeigt werden, dass es bei keinem der 154 Patienten zu einem Übergang von einer akuten in eine chronische Epididymits kam. Dezente Skrotalbeschwerden sind auch bei gesunden Männern nicht selten und wurden entsprechend auch in der vorliegenden Studie beschrieben. Jedoch sprechen die deutliche Abnahme der Schmerzintensität im Verlauf und die Normalisierung der Entzündungsparameter im Ejakulat gegen die Entwicklung einer chronischen Nebenhodenentzündung. Das Auftreten von Rezidiven nach akuter Nebenhodenentzündung ist möglich und kann nach unseren Ergebnissen mit ca. 11% angegeben werden. Ein begünstigender Faktor für das Auftreten eines Rezidivs konnte nicht identifiziert werden. Es konnte gezeigt werden, dass es nach leitliniengerechter antibiotischer Therapie zwar initial in der Frühphase nach akuter Epididymitis zur Beeinträchtigung der Ejakulatparameter, im Verlauf jedoch zur Verbesserung der Spermienparameter und zum Erhalt der Fertilität kommt. Eine epididymale Obstruktion bzw. eine Beeinträchtigung der Nebenhodenfunktion als Folge der akuten Epididymitis ist aufgrund der erhobenen Sexualhormonbefunde wahrscheinlich. Eine langfristige Schädigung des Hodenparenchyms bestätigte sich jedoch nicht. Erstmalig konnte gezeigt werden, dass keiner der Studienpatienten eine klinische Infertilität (unerfüllter Kinderwunsch über einen Zeitraum von 12 Monaten hinaus) aufwies.Acute Epididymitis is a common urological disease pattern, which is often caused by sexually transmitted or uropathogenic bacteria. Not only is the course of disease accompanied by violent pain and sickness, but also potentially occuring longlasting consequences, such as chronic pain and inflammation, relapses of the epididymitis and infertility can influence the physical and mental health of the affected person. Nevertheless, research on longterm consequences of acute epididymitis is incomprehensive. For this study we recruited 228 men (median of age 53 years) who were examined for acute epididymitis in the urological departement of the university hospital in Gießen between 2007 and 2013. Patients were included in the clinical study as far as at least 12 months had past since the onset of acute epididymitis. Furthermore, we succeeded to document the course of disease in 154 men by the questionnaire „Probleme und Beschwerden nach der Nebenhodenentzündung“. In addition 120 patients completed the Chronic Epididmitis Symptom Index questionnaire. During the Longterm-Follow-Up a semen analysis was done for 21 patients (median Follow-Up 61 months) and blood samples for investigations on the sex hormones FSH, LH and Testosteron were taken. For evaluating male fertility after acute epididymitis we used as surrogates the basic parameters concentration, progressive motility and percentage of physiologically shaped spermatozoa in the ejaculate. Beyond that we evaluated the function of prostate, epididymis and seminal vesicles. Additionally, the inflammation parameters elastase of granulocytes and peroxidase postive leukocytes were measured. Every result of each parameter was compared to previous analyses which were done 14 and 84 days after the onset of acute epididymitis. Since only a fairly small number of 21 men participated in the investigation during the Longterm-Follow- Up (group of Longterm-Follow-Up), we also compared the collected results of analyses which were taken 14 and 84 days after acute epididymitis of all recruited patients (group of Shortterm-Follow-Up). Moreover informations about fertility and occured pregnancies after acute epididymitis were collected. In this study we were able to show that chronification of epididymitis did not occur in any of the 154 cases. Nevertheless slight scrotal discomfort is common even in healthy men and was also present in this study. However the obvious reduction of pain intensity and decreasing inflammatory parameters in the semen count against the development of a chronic epididymitis. Considering our results recurrences of acute epididymitis approximately occur in 11% of the cases. We were not able to reveal any predicting factors that may influence the possibility of suffering from recurrent epididymitis. We succeeded to provide evidence that in those cases guidelines on antibiotic treatment of acute epididymitis were followed male fertility was preserved. Although initally semen quality was impaired we were able to demonstrate a significant improvement in the course. An obstruction of the epididymal ducts or an impairment of the epididymal tissue function as a result of acute epididymitis are assumable as indicated by the collected data of sex hormones. However a longterm damage of testicular tissue appears less likely. For the first time, the study could demonstrate that no study participant complained of post- inflammatory infertility

Generating Inviscid and Viscous Fluid Flow Simulations over a Surface Using a Quasi-simultaneous Technique

A fluid-flow simulation over a computer-generated surface is generated using a quasi-simultaneous technique. The simulation includes a fluid-flow mesh of inviscid and boundary-layer fluid cells. An initial fluid property for an inviscid fluid cell is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. An initial boundary-layer fluid property a boundary-layer fluid cell is determined using the initial fluid property and a viscous fluid simulation that simulates fluid viscous effects. An updated boundary-layer fluid property is determined for the boundary-layer fluid cell using the initial fluid property, initial boundary-layer fluid property, and an interaction law. The interaction law approximates the inviscid fluid simulation using a matrix of aerodynamic influence coefficients computed using a two-dimensional surface panel technique and a fluid-property vector. An updated fluid property is determined for the inviscid fluid cell using the updated boundary-layer fluid property

Hydrocephalus in Tuberculous Meningitis

Hydrocephalus is a frequent complication of tuberculous meningitis. We present the incidence of hydrocephalus in patients diagnosed with tuberculosis of the nervous system, the therapeutic possibilities and the evolution of these patients. A consensus definition for tuberculous meningitis (TBM) stratified the cases as definite, probable and possible. In various studies, radiological investigations (CT, MRI) can be normal in the initial stages of the disease in approximately 30% of cases, but they do not exclude the possibility of a TBM. The most common radiological changes found in TBM are communicating hydrocephalus (up to 80% of cases), increased basal contrast (50%), cerebral tuberculomas (30%) and cerebral infarcts (10–40%). MRI has been shown to be more sensitive than a CT scan for diagnosed TBM. Communicating hydrocephalus is among the short-term complications of TBM (approximately 80% of cases), being more frequent than non-communicating ones. In these cases, the need to perform a ventriculo-peritoneal unit must be taken into account. Long-term complications are cognitive impairment, epilepsy, stroke, hydrocephalus, myelitis, damage to the hypothalamus or the pituitary gland manifested by obesity, growth disorders and diabetes insipidus. Sequels may occur frequently in TBM such as dementia, epilepsy, neurological deficits, behavioral disorders, blindness and deafness

Design and construction of a small ducted fan engine for nonlinear control experiments

This paper describes the design and construction of a small ducted fan engine which is being used for experimental research in robust nonlinear control of high-performance vectored thrust aircraft. The fan consists of a high-efficiency electric motor with a 6-inch diameter blade, capable of generating up to 9 Newtons of thrust. Flaps on the fan allow the thrust to be vectored from side to side and even reversed. The engine is mounted on a three degree of freedom stand which allows horizontal and vertical translation as well as unrestricted pitch angle. We give a detailed description of the design and construction of the fan and its analytical and empirical models. Initial PID controllers for altitude and pitch angle stabilization are included to verify the system model and indicate future avenues of research

Survey on brachytherapy training among radiation oncology residents in the German-speaking regions of Europe.

PURPOSE This survey aimed to determine the perception of brachytherapy training among residents in the DACH region, consisting of Austria, Germany and Switzerland. MATERIAL & METHODS An online questionnaire containing 22 questions related to trainee demographics (n = 5) and to brachytherapy training (n = 17) was sent in two iterations in 11/2019 and 02/2020. The following topics were evaluated: institutional support, barriers to training, extent of training, site-specific training (prostate, gynaecology, breast, gastrointestinal and skin), preferences for further training and outlook on overall development of brachytherapy. The responses were mostly based on a Likert scale of 1 to 5, thereby reflecting strength of opinion. Descriptive statistics were used to describe frequencies. RESULTS Among the 108 respondents, approximately 69% of residents considered the ability to perform brachytherapy independently to be important or somewhat important. However, only 31% of respondents reported to have a dedicated brachytherapy training during residency. The major limitation to achieve independence in performing brachytherapy was seen in a low case load in Austria, in the lack of training in Switzerland and in both of them in Germany. CONCLUSION The interest in brachytherapy training among residents in German-speaking countries was generally high, but there is a perceived lack of sufficient case volumes and partially also in formal training opportunities. Fellowships at departments with a high case load as part of a formalised curriculum and dedicated hands-on workshops at national or international conferences might help to overcome these issues