Block-tridiagonal linear systems and branched continued fractions

Mathematics

Discussion on complexity and TCAS indicators for coherent safety net transitions

Transition between Separation Management in ATM and Collision Avoidance constitutes a source of potential risks due to non-coherent detection and resolution clearances between them. To explore an operational integration between these two safety nets, a complexity metric tailored for both Separation Management and Collision Avoidance, based on the intrinsic complexity, is proposed. To establish the framework to compare the complexity metric with current Collision Avoidance detection metrics, a basic pair-wise encounter model has been considered. Then, main indicators for horizontal detection of TCAS, i.e. tau and taumod, have been contrasted with the complexity metric. A simple method for determining the range locus for specific TCAS tau values, depending on relative speeds and encounter angles, was defined. In addition, range values when detection thresholds were infringed have been found to be similar, as well as its sensitivity to relative angles. Further work should be conducted for establishing a framework for the evaluation and validation of this complexity metric. This paper defines basic principles for an extended evaluation, including multi-encounter scenarios and longer look ahead times

Effects of total knee arthroplasty on ankle alignment in patients with varus gonarthrosis : do we sacrifice ankle to the knee?

Total knee arthroplasty is one of the most commonly preferred surgical methods in the treatment of patients with varus gonarthrosis. In this study, we aimed to evaluate the radiological changes observed in the ankles after total knee arthroplasty. Between May 2012 and June 2013, 80 knees of 78 patients with varus deformity over 10A degrees underwent total knee arthroplasty. For each patient, full-leg standing radiographs were obtained pre- and post-operatively. Mechanical and anatomical axes (HKA and AA), lateral distal femoral angle, medial proximal tibial angle, lateral distal tibial angle (LDTA), ankle joint line orientation angle (AJOA), tibial plafond talus angle (PTA) and talar shift were measured for each patient both pre- and post-operatively. Pre-operatively, the mean HKA was 16.6A degrees and the mean AA was 10.41A degrees, both in favour of varus alignment. Post-operatively, the mean HKA decreased to 3.6A degrees and the mean AA to -2.1. The mean LDTA was 87.3A degrees. Before the operation, the mean AJOA was -7.6A degrees, opening to the medial aspect of the ankle, and it was 0.04A degrees after the operation and opening to the lateral aspect (p < 0.05). Our study reveals the changes occurring in the ankle after acute correction of long-standing varus deformity of the knee using total knee arthroplasty. In cases undergoing knee arthroplasty, effect of the acute change in the alignment of the knee on the ankle should be taken into consideration and the amount of correction should be calculated carefully in order not to damage the alignment of the ankle

Imaging findings after meniscal repair with degradable polyurethane scaffold: preliminary results.

Purpose / Introduction: To date, there are no satisfactory solutions to the meniscal originated knee pain post meniscal tear repair. In this study a newly developed polyurethane material that has the intended properties of reducing pain and inducing tissue growth in a damaged meniscus is tested. Materials and Methods: All patients will be imaged using conventional and dynamic MR imaging techniques at 1 week and 3, 12 and 24 months after surgery. The influx of gadolinium contrast in a tissue during the first three minutes after injection gives a measure of the vascularisation, capillary permeability, perfusion and composition of the interstitial fluid. It can be measured using dynamic MRI and is represented as a Time Intensity Curve (TIC). This curve permits an evaluation of the healing process after surgery. Discussion / Conclusion: Thus far 11 patients have received meniscal implants. Eight medial and three lateral menisci were operated. All implants covered the posterior horn with 3 reaching halfway into the meniscal body and one extending into the anterior horn. The average length of the scaffold meniscus measured on MR imaging was 45mm. In the first week after surgery, the capsule and suture area display fast and intense enhancement typical for post-operative inflammation and the formation of early scar-tissue. There is no enhancement in the base or the tip of the scaffold meniscus. After three months the speed and intensity of enhancement in the capsule and suture area between the remnants of the native meniscus and the scaffold have decreased indicating maturation of scar-tissue. However, the base of the scaffold meniscus now shows enhancement. This can only be explained by proliferation of blood vessels from the capsule and theresidual meniscus wall into the scaffold meniscus. The tip of the matrix shows limited enhancement in some patients after three months. On anatomical MR images, the signal intensity (SI) of the implanted scaffold is close to that of water on both T1- and T2-weighted spin echo and turbo spin echo sequences in the first week. After three months the SI decreases but is still clearly higher than that of the native meniscus. The implants in the posterior horn all had a normal position and no loosening of the sutures or tears of the scaffold were found. After three months, one of the patients had slight expulsion of body of the scaffold meniscus but this is a common finding in transplanted menisci

The human meniscus: transplantation, characterisation and tissue engineering

The Human Meniscus: Transplantation, Characterization and Tissue Engineering Peter Verdonk, MD, PhD; Ghent University, Belgium Abstract The meniscus plays an important role in the complex biomechanics of the knee joint. Removal of this tissue can result in dysfunction and pain in the involved joint compartment and ultimately osteoarthritis. We report on the surgical technique, the clinical and radiological outcome after substitution of the human meniscus with a viable allograft. The results of this type of surgery are encouraging and long-lasting in a well-selected patient population who suffered a total meniscectomy. Viable meniscus allograft transplantation significantly reduces pain and improves function. This beneficial effect remains present in around 70% of the patients at 10 years after surgery. In light of the higher number of partial meniscectomies in the clinical office, further attention was paid to develop tissue engineering strategies to restore and regenerate meniscus tissue without the intrinsic drawback of the use of allogeneic material. A first study aimed at the characterization of the human meniscus cell associated matrix (CAM) synthesis and turnover in two different culture conditions. The alginate culture conditions appear to favor the fibrochondrocyte meniscus cells with a CAM rich in type I collagen and aggrecan and lower quantities of type II collagen, while monolayer cultured meniscus cells have considerable amounts of type I and II collagen but almost no aggrecan in their CAM. Additional investigations led to the description of a new cell-type within the superficial layer of the normal meniscus; the CD34+ meniscus cell. In a second study, we demonstrated that human bone marrow derived mesenchymal stem cells in combination with a type I collagen scaffold have a fibrochondrogenic differentiation potential. This cell-scaffold combination is implantable and could easily deliver autologous hBMSC with meniscus repair potential to the defect. The ultimate goal of meniscus transplantation and tissue engineering is to prevent the degenerative process induced by a partial or total meniscectomy and inflicted upon the articular cartilage. Therefore, metabolic pathways (IGF-1, IL-1, IL-1RII) were investigated in the articular chondrocyte that could be targeted by specific pharmaceuticals (polysulphated cyclodextrines) in order to upregulate an anabolic effect. The use of these substances could improve the results of meniscus substitution procedures in secondary osteoarthritic knee joints

The contribution of the Spanish language in Flanders to the lexicon of general Spanish at the end of the 16th and during the 17th century

El examen exhaustivo de un corpus de manuscritos e impresos (1,5 millón de registros) redactados por miembros del personal político, militar y religioso español que sirvió en los Estados de Flandes (1567-1706) permite observar el uso de neologismos completamente desconocidos en el español de la Península (por ej. drosarte, liarte, marrazo ‘tierra pantanosa’) o que no aparecerán allí sino medio siglo más tarde (por ej. recluta y tren). Casi todos estos neologismos se tomaron de las variedades románicas de los Estados de Flandes (picardo y valón), además del francés estándar, que no solo se hablaba en la parte meridional del país, sino que lo practicaban también las clases altas (aristocracia, comerciantes, etc.) de la parte septentrional del país, donde el pueblo hablaba el neerlandés o uno de susdialectos. El uso de estos (y otros más) neologismos peculiares en la lengua española de Flandes tiene como consecuencia que el español de Flandes merece tratarse en adelante, por lo menos desde el punto de vista lexicológico, como una variante peculiar del español áureo.El examen exhaustivo de un corpus de manuscritos e impresos (1,5 millón de registros) redactados por miembros del personal político, militar y religioso español que sirvió en los Estados de Flandes (1567-1706) permite observar el uso de neologismos completamente desconocidos en el español de la Península (por ej. drosarte, liarte, marrazo ‘tierra pantanosa’) o que no aparecerán allí sino medio siglo más tarde (por ej. recluta y tren). Casi todos estos neologismos se tomaron de las variedades románicas de los Estados de Flandes (picardo y valón), además del francés estándar, que no solo se hablaba en la parte meridional del país, sino que lo practicaban también las clases altas (aristocracia, comerciantes, etc.) de la parte septentrional del país, donde el pueblo hablaba el neerlandés o uno de susdialectos. El uso de estos (y otros más) neologismos peculiares en la lengua española de Flandes tiene como consecuencia que el español de Flandes merece tratarse en adelante, por lo menos desde el punto de vista lexicológico, como una variante peculiar del español áureo.El examen exhaustivo de un corpus de manuscritos e impresos (1,5 millón de registros) redactados por miembros del personal político, militar y religioso español que sirvió en los Estados de Flandes (1567-1706) permite observar el uso de neologismos completamente desconocidos en el español de la Península (por ej. drosarte, liarte, marrazo ‘tierra pantanosa’) o que no aparecerán allí sino medio siglo más tarde (por ej. recluta y tren). Casi todos estos neologismos se tomaron de las variedades románicas de los Estados de Flandes (picardo y valón), además del francés estándar, que no solo se hablaba en la parte meridional del país, sino que lo practicaban también las clases altas (aristocracia, comerciantes, etc.) de la parte septentrional del país, donde el pueblo hablaba el neerlandés o uno de susdialectos. El uso de estos (y otros más) neologismos peculiares en la lengua española de Flandes tiene como consecuencia que el español de Flandes merece tratarse en adelante, por lo menos desde el punto de vista lexicológico, como una variante peculiar del español áureo.The exhaustive analysis of a corpus of manuscripts and books (1,5 million of records) redacted by Spanish members of the politic, military and religious staff being on duty in Flanders (1567-1706) allows us to observe the use of neologisms which were completely unknown in the Spanish language of the Peninsula (for ex. drosarte, liarte, marrazo ‘swamp’) or which will not appear there until half a century later (for ex. Recluta y tren). Nearly all these neologisms were borrowed from the Romanic varieties of Flanders (Picard and Walloon), besides standard French, which was not only the main language of the southern part, but was also used by the higher classes of the northernpart of the country, where people spoke Dutch or one of its dialects. The consequence of the use of these (and others) neologisms peculiar to the Spanish language of Flanders is that henceforward the Spanish language of this area merits the treatment, at least from a lexical point of view, as a peculiar variant of the Spanish of the Golden Age