Asymptotic Analysis of Thin Interface in Composite Materials with Coated Boundary

This paper considers the problem of thin interface in a fibre reinforced composite material. Using the singular asymptotic procedure, the authors obtain simplified relations known as spring model. Phenomenon of edge effect is also studied using the Papkovich-Fadle approach. The singularities of the limit problem are analysed

A Robust Solution Procedure for Hyperelastic Solids with Large Boundary Deformation

Compressible Mooney-Rivlin theory has been used to model hyperelastic solids, such as rubber and porous polymers, and more recently for the modeling of soft tissues for biomedical tissues, undergoing large elastic deformations. We propose a solution procedure for Lagrangian finite element discretization of a static nonlinear compressible Mooney-Rivlin hyperelastic solid. We consider the case in which the boundary condition is a large prescribed deformation, so that mesh tangling becomes an obstacle for straightforward algorithms. Our solution procedure involves a largely geometric procedure to untangle the mesh: solution of a sequence of linear systems to obtain initial guesses for interior nodal positions for which no element is inverted. After the mesh is untangled, we take Newton iterations to converge to a mechanical equilibrium. The Newton iterations are safeguarded by a line search similar to one used in optimization. Our computational results indicate that the algorithm is up to 70 times faster than a straightforward Newton continuation procedure and is also more robust (i.e., able to tolerate much larger deformations). For a few extremely large deformations, the deformed mesh could only be computed through the use of an expensive Newton continuation method while using a tight convergence tolerance and taking very small steps.Comment: Revision of earlier version of paper. Submitted for publication in Engineering with Computers on 9 September 2010. Accepted for publication on 20 May 2011. Published online 11 June 2011. The final publication is available at http://www.springerlink.co

Lifting the veil of secrecy: maternal and neonatal outcome of oocyte donation pregnancies in Germany

Background: In Germany, performing fertility procedures involving oocyte donation is illegal, as stated by the Embryo Protection Law. Nonetheless, in our clinical routine we attend to a steadily rising number of pregnant women, who have sought oocyte donation abroad. Due to the legal circumstances many women opt to keep the origin of their pregnancy a secret. However, studies have shown, that oocyte donation is an independent risk factor for the development of pregnancy complications, such as preeclampsia. Objective: The aim of this study is to evaluate maternal and neonatal outcomes of oocyte donation pregnancies in three large obstetric care units in Berlin, Germany. Methods: We retrospectively analyzed all available medical data on oocyte donation pregnancies at Charite University hospital, Vivantes Hospital Friedrichshain, and Neukoelln in the German capital. Results: We included 115 oocyte donation (OD) pregnancies in the present study. Our data are based on 62 singleton, 44 twin, 7 triplet, and 2 quadruplet oocyte donation pregnancies. According to our data, oocyte donation pregnancies are associated with a high risk of adverse maternal and fetal outcome, i.e., hypertension in pregnancy, preterm delivery, Cesarean section as mode of delivery, and increased peripartum hemorrhage. Conclusion: Although oocyte donation is prohibited by German law, many couples go abroad to seek reproductive measures using oocyte donation after former treatment options have failed. OD pregnancies are associated with a high risk of preeclampsia, C-section as mode of delivery, and peripartum hemorrhage. Detailed knowledge of the associated risks is of utmost importance to both the patient and the treating physician and midwife

Traditional vs Gesture Based UAV Control

Abstract. The purpose of this investigation was to assess user preferences for controlling an autonomous system. A comparison using a virtual environment (VE) was made between a joystick based, game controller and a gesture-based system using the leap motion controller. Command functions included basic flight maneuvers and switching between the operator and drone view. Comparisons were made between the control approaches using a representative quadcopter drone. The VE was designed to minimize the cognitive loading and focus on the flight control. It is a physics-based flight simulator built in Unity3D. Participants first spend time familiarizing themselves with the basic controls and vehicle response to command inputs. They then engaged in search missions. Data was gathered on time spent performing tasks, and post test interviews were conducted to uncover user preferences. Results indicate that while th

Class I histone deacetylases 1, 2 and 3 are highly expressed in renal cell cancer

Background Enhanced activity of histone deacetylases (HDAC) is associated with more aggressive tumour behaviour and tumour progression in various solid tumours. The over-expression of these proteins and their known functions in malignant neoplasms has led to the development of HDAC inhibitors (HDI) as new anti-neoplastic drugs. However, little is known about HDAC expression in renal cell cancer. Methods We investigated the expression of HDAC 1, 2 and 3 in 106 renal cell carcinomas and corresponding normal renal tissue by immunohistochemistry on tissue micro arrays and correlated expression data with clinico-pathological parameters including patient survival. Results Almost 60% of renal cell carcinomas expressed the HDAC isoforms 1 and 2. In contrast, HDAC 3 was only detected in 13% of all renal tumours, with particular low expression rates in the clear cell subtype. HDAC 3 was significantly higher expressed in pT1/2 tumours in comparison to pT3/4 tumours. Expression of class I HDAC isoforms correlated with each other and with the proliferative activity of the tumours. We found no prognostic value of the expression of any of the HDAC isoforms in this tumour entity. Conclusion Class I HDAC isoforms 1 and 2 are highly expressed in renal cell cancer, while HDAC 3 shows low, histology dependent expression rates. These unexpected differences in the expression patterns suggests alternative regulatory mechanisms of class I HDACs in renal cell cancer and should be taken into account when trials with isoform selective HDI are being planned. Whether HDAC expression in renal cancers is predictive of responsiveness for HDI will have to be tested in further studies