Two-dimensional gravitation and Sine-Gordon-Solitons

Some aspects of two-dimensional gravity coupled to matter fields, especially to the Sine-Gordon-model are examined. General properties and boundary conditions of possible soliton-solutions are considered. Analytic soliton-solutions are discovered and the structure of the induced space-time geometry is discussed. These solutions have interesting features and may serve as a starting point for further investigations.Comment: 23 pages, latex, references added, to appear in Phys.Rev.

A systems biology approach to bovine fertility and metabolism: Introduction of a glucose insulin model

To counteract the antagonistic relationship between milk yield and fertility in dairy cow, a deeper understanding of the underlying biological mechanisms is required. For this purpose, we study physiological networks related to reproduction and metabolism in dairy cows. We interactively develop dynamic, mechanistic models by fitting the models to experimental data and mechanistic knowledge. We have already developed models for potassium balance and hormonal regulation of fertility in the dairy cow, which will briefly be reviewed here. The main focus of this article is a glucose-insulin model currently developed by us. This model links the bovine hormonal cycle and the potassium balance to glucose and thus to energy metabolism. The models can be applied in scientific research, education, experimental planning, drug development and production on farms

Versorgung von Hand- und Fingerfrakturen mit dem Stryker-Handplattensystem

Objectives: 10% of all fractures occur in the fingers and metacarpal region. Early mobilization with preservation of grip function is the goal of any therapy for these injuries. Osteosyntheses with plates are used in complex fractures that do not allow any other treatment. The aim of this retrospective study was to evaluate the performance and safety of the Stryker Hand System.Patients and methods: Between 2010 and 2019, 190 patients underwent surgical treatment with plates for fractures of the fingers and metacarpal region. Of these, 140 operations could be analyzed according to the inclusion criteria based on clinical and radiological parameters.Results: Three-quarters of the patients were male. The mean age at the time of surgery was 39.3±16 years. Falling was the leading cause for hand fractures, and the most common were fractures of the shaft (>52%). More than 15% were complex hand injuries with more than one fractured finger. The majority of patients were healthy non-smokers without systemic diseases and relevant medical history.Conclusion: The Stryker Finger Plates are safe implants with good results that are consistent with those reported in the literature. The trend is also toward stable-angle implants for fracture treatment of the finger, in order to enable the earliest possible functional, safe mobilization.Level of Evidence: Level: IV; outcome-study, retrospectiveZielsetzung: 10% aller Frakturen treten an Fingern und Mittelhand auf. Eine frühe Mobilisierung mit Erhalt der Greiffunktion ist das Ziel jeder Therapie dieser Verletzungen. Osteosynthesen mit Platten werden bei komplexen Frakturen eingesetzt, die eine andere Behandlung nicht zulassen. Das Ziel dieser retrospektiven Studie war es, die Leistungsfähigkeit und Sicherheit des Stryker-Hand-Systems zu evaluieren.Patienten und Methoden: Zwischen 2010 und 2019 wurden 190 Patienten bei Frakturen im Bereich der Finger und Mittelhandknochen mit Platten operativ versorgt. Davon konnten 140 Operationen nach den Einschlusskriterien anhand von klinischen und radiologischen Parametern analysiert werden.Ergebnisse: Drei Viertel der Patienten waren männlich. Das mittlere Alter zum Zeitpunkt der Operation betrug 39,3±15,97 Jahre. Stürze waren die häufigste Ursache für Handfrakturen, am häufigsten waren Schaftfrakturen (>52%). Mehr als 15% waren komplexe Handverletzungen mit mehr als einem gebrochenen Finger. Die Mehrzahl der Patienten waren gesunde Nichtraucher ohne systemische Erkrankungen und relevante Anamnese.Schlussfolgerung: Die Stryker-Fingerplatten sind sichere Implantate mit guten Ergebnissen, die mit den in der Literatur berichteten Ergebnissen übereinstimmen. Der Trend geht auch bei der Frakturversorgung des Fingers zu winkelstabilen Implantaten, um eine frühestmögliche funktionelle, sichere Mobilisierung zu ermöglichen.Evidenzgrad: IV; retrospektive Ergebnis-Studi

Exploration of different wave patterns in a model of the bovine estrous cycle by Fourier analysis

Cows typically have different numbers of follicular waves during their hormonal cycle. Understanding the underlying regulations leads to insights into the reasons for declined fertility, a phenomenon that has been observed during the last decades. We present a systematic approach based on Fourier analysis to examine how parameter changes in a model of the bovine estrous cycle lead to different wave patterns. Even without any biological considerations, this allows to detect the responsible model parameters that control the type of periodicity of the solution, thus supporting experimental planning of animal scientists

Mechanisms regulating follicle wave patterns in the bovine estrous cycle investigated with a mathematical model

A normal bovine estrous cycle contains 2 or 3 waves of follicle development, and ovulation takes place in the last wave. However, the biological mechanisms that determine whether a cycle has 2 or 3 waves have not been elucidated. In a previous paper, we described a mathematical model of the bovine estrous cycle that generates cyclical fluctuations of hormones, follicles, and corpora lutea in estrous cycles of approximately 21 d for cows with a normal estrous cycle. The parameters in the model represent kinetic properties of the system with regard to synthesis, release, and clearance of hormones and growth and regression of follicles and corpora lutea. The initial model parameterization resulted in estrous cycles with 3 waves of follicular growth. Here, we use this model to explore which physiological mechanisms could affect the number of follicular waves. We hypothesized that some of the parameters related to follicle growth rate or to the time point of corpus luteum regression are likely candidates to affect the number of waves per cycle. We performed simulations with the model in which we varied the values of these parameters. We showed that variation of (combinations of) model parameters regulating follicle growth rate or time point of corpus luteum regression can change the model output from 3 to 2 waves of follicular growth in a cycle. In addition, alternating 2- and 3-wave cycles occurred. Some of the parameter changes seem to represent plausible biological mechanisms that could explain these follicular wave patterns. In conclusion, our simulations indicated likely parameters involved in the mechanisms that regulate the follicular wave pattern, and could thereby help to find causes of declined fertility in dairy cows