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

Preeclampsia, the Renin-Angiotensin-Aldosterone System and beyond

__Abstract__ The renin-angiotensin-aldosterone system (RAAS) plays an essential role in the regulation of blood pressure and body fluid homeostasis, but also contributes importantly to the pathophysiology of hypertension, renal disease and heart failure. Clinically, the RAAS is of great interest as inhibition at different levels has been proven to be an effective therapy for hypertension, cardiovascular and renal disease. Angiotensin II mediates its effects via angiotensin II type 1 (AT1) and angiotensin II type 2 (AT2) receptors. AT1-receptors are widely expressed throughout the body and mediate the well-known effects of angiotensin II, including vasoconstriction, sympathetic nervous system activation and sodium and water retention. While experimental studies show that stimulation of the AT2-receptor counteracts these effects by inducing vasorelaxation and natriuresis in healthy animals, our knowledge about AT2-receptor function in humans is limited to a few studies, showing, at most, modest vasodilatory effects upon AT2-receptor stimulation. In contrast to the beneficial effects, recent studies suggest

The use of computer-assisted orthopedic surgery for total knee replacement in daily practice: a survey among ESSKA/SGO-SSO members

Computer-assisted orthopedic surgery (CAOS) for total knee arthroplasty is an emerging surgical tool, yet little is known about how it is being used in everyday orthopedic centers. We sought to better understand physicians' current practices and beliefs on this topic through performing a Web-based survey. Between December 2006 and January 2007, a 24-question survey was emailed to 3,330 members of the European Society of Sports Traumatology Knee Surgery and Arthroscopy (ESSKA) and the Swiss Orthopedic Society (SGO-SSO), with 389 (11.7%) agreeing to participate. Of this group, 202 (51.9%) reported that their center was equipped with a navigation system, which was an image-free based system for most (83.2%) and was primarily used for total knee arthroplasty (61.4%). In terms of the proportion of use, 50.5% of respondents used their navigation system in less than 25% of cases, 16.3% in 25-50% of cases, 7.4% in 51-75% of cases, and 25.7% in more than 75% of cases. The potential for improving the alignment of prosthesis was the most strongly cited reason for using a navigation system, while the potential for increasing operation times and the risk of infections were the most strongly cited reasons for not using a navigation system. Approximately half of respondents surveyed believed navigation systems were a real innovation contributing to the improvement of total knee implantation. However, heavy usage of computer-assisted navigation (≥51% of cases) was observed in only 33.1% of respondents, with only a quarter using it at rates that could be considered frequent (>75% of cases). Forty-eight percent of respondents said they will use a navigation system in more cases and 39.1% that their usage will stay the same. These findings indicate that CAOS is being used only moderately in current practices, though respondents generally had a positive opinion of its potential benefits. Physicians may be awaiting more data before adopting the use of these systems, though survey responses also suggest a projected increase in their use in the coming year

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