Local Regulation of Arterial Tone: an Insight into Wall Dynamics Using Mathematical Models

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.We present herein a first attempt to integrate large and small scale phenomena within an image-based computational domain. The aim of the present study is to highlight some of the underlying mechanisms that govern cellular interaction in the vascular wall, using a nonlinear model of vasomotion. We show that macroscopic rhythmic activity and emergent phenomena can indeed reflect ion movements at the level of the individual cell

Topological Symmetry Groups of K_{4r+3}

We present the concept of the topological symmetry group as a way to analyze the symmetries of non-rigid molecules. Then we characterize all of the groups which can occur as the topological symmetry group of an embedding of the complete graph K_{4r+3} in S^3

Die Biologie der Heilung der Rotatorenmanschettenläsion: Welche Rolle spielen Wachstumsfaktoren heutzutage?

Zusammenfassung: Die Rotatorenmanschettenläsion ist eine häufige Diagnose in der orthopädischen Sprechstunde. Die Rerupturrate ist trotz Weiterentwicklung der Nahtmaterialien und -techniken im offenen und arthroskopischen Bereich nach wie vor hoch. In den letzten Jahren wurden den physiologischen Vorgängen der natürlichen Insertion wie auch den biologischen Eigenschaften der Rotatorenmanschettenheilung in der Forschung vermehrt Aufmerksamkeit geschenkt. Es hat sich gezeigt, dass die Heilung der Sehnen-Knochen-Insertion der Rotatorenmanschette ein komplexes Zusammenspiel von lokalen Zellen, Stammvorläuferzellen, extrazellulärer Matrix sowie von Wachstumsfaktoren und anderen Zytokinen ist. Dementsprechend wurden verschiedene biologische In-vitro- und In-vivo-Therapieverfahren zur potenziellen Verbesserung der Reinsertion entwickelt. Ziel dieses Artikels ist es, einen Überblick über die heutige Evidenz der Augmentation der Rotatorenmanschettenrekonstruktion mit Wachstumsfaktoren zu geben. Weiterhin werden mögliche zukünftige Therapieansätze diskutier

Intraoperative biologische Augmentation an Sehnen und Enthesen

Zusammenfassung: Trotz technischer Weiterentwicklung in der Sehnenrekonstruktionschirurgie besteht postoperativ nach wie vor eine relativ hohe Rerupturrate. Ein Grund dafür ist die Tatsache, dass bei der Sehnenansatz- und Sehnenheilung, bedingt durch eine limitierte Regenerationskapazität, Narbengewebe anstelle von normalem Gewebe gebildet wird. Dieses Narbengewebe ist sowohl in funktioneller als auch struktureller Sicht dem normalen Gewebe unterlegen. Mehrere Strategien zur biologischen Augmentation von Sehnen- und Sehnenansatzläsionen wurden in den letzten Jahren entwickelt und getestet. Dieser Artikel bespricht die klinische Evidenzlage bezüglich der biologischen Augmentation von Sehnen und Enthesen mittels Wachstumsfaktoren in Form von Plättchenkonzentraten, zellbasierten Therapien bzw. biologischen Sehnengraft

Defining the Field: Revisiting the ACA 1995 Definition of Communication Studies

This article deals with the problem of defining communication studies in higher education. In 1995, the Association for Communication Administration (ACA) convened a summer conference that produced a two-sentence definition of the field of communication. More than 100 conferees voted their unanimous approval of the definition, which was then disseminated nationally and used by communication scholar/teachers for a multiplicity of purposes. Given the potential utility of that definition and the expansion of communication studies since 1995, the present study surveyed ACA\u27s current members to determine whether they are aware the definition exists, how they have used it, and the extent to which they perceive it as representative of communication studies today. The results of that survey are reported in this article, which begins with a description of why and how this definition was originally developed. In a field as diverse and eclectic as communication, a need exists for some commonality of understanding about what constitutes the discipline\u27s subject matter. Such understanding, in the form of a definition, can serve two functions: it can provide a descriptor of the diversity, breadth, and depth of the field itself; and, it can be used to represent the discipline to an external audience, both inside and outside of academe, many of whom may still hold onto the notion that the field is committed only to the practice and study of speech making

Four-strand hamstring tendon autograft for ACL reconstruction in patients aged 50years or older

SummaryIntroductionReconstruction of the anterior cruciate ligament using a four-strand hamstring tendon autograft in symptomatic patients aged 50years or older is an accepted treatment option.HypotesisFour-strand hamstring tendon autograft although not universally utilized in patients who are at least 50years old is an efficient procedure to control knee instability.Material and methodsIn this retrospective, we analyzed the clinical outcomes of 18patients treated from September 1998 to September 2003. Criteria for inclusion were the following: age above 50years at surgery, chronic anterior laxity associated or not with meniscal damage; one or more episodes of knee instability and no prior ligament surgery on the involved knee. A same operative technique (arthroscopic single-bundle four-strand hamstring reconstruction, blind femoral tunnel, through anteromedial portals), a same fixation type (absorbable interference screws in femur and tibia) and a same rehabilitation protocol were used for all these knees. The IKDC 93scores were determined pre- and postoperatively combined with anteroposterior and lateral views, single leg stance, 30° flexion stance, and passive Lachman test (Telos) postoperatively.ResultsAt mean 30month-follow-up (range 12–59months), there were no graft failure and no loss of extension for any of these knees. Three patients complained of hypoesthesia in the medial saphenous nerve territory and one patient experienced posterior knee pain. All patients graded their knee as normal or nearly normal, all were satisfied or very satisfied with their operation. None of the patients reported instability. The Lachman-Trillat test was noted “firm end point” in 14knees and “delayed firm end point” in four. The pivot-shift test was negative in 16knees and mild positive in two. The mean residual differential laxity was 3.1mm (0 to +6mm) for the passive Lachman test. At last follow-up, the overall IKDC score was 7A, 7B, 3C, and 1 D. Patients with preserved meniscus (nine patients) reported a lesser degree of pain and a better residual laxity control compared with patients who had undergone a meniscectomy.ConclusionAge over 50years is not a contraindication to select a hamstring tendon autograft for ACL reconstruction. This surgery can restore knee stability but does not modify the pain pattern in patients, who had a medial meniscectomy prior to the ACL reconstruction.Level of evidence: level IV, therapeutic study

A comparative study of fractional step method in its quasi-implicit, semi-implicit and fully-explicit forms for incompressible flows

The present review describes and analyses a class of finite element fractional step methodsfor solving the incompressible Navier-Stokes equations. Our objective is not to reproduce the extensivecontributions on the subject, but to report on our long-term experience with and provide a unified overviewof a particular approach: the characteristic based split method. Three procedures, the semi-implicit, quasi-implicit and fully-explicit, are studied and compared. This work provides a thorough assessment of theaccuracy and efficiency of these schemes, both for a first and second order pressure split. In transientproblems, the quasi-implicit form significantly outperforms the fully-explicit approach. The second order(pressure) fractional step method displays significant convergence and accuracy benefits when the quasi-implicit projection method is employed. The fully-explicit method, utilising artificial compressibility and apseudo time stepping procedure, requires no second order fractional split to achieve second order or higheraccuracy. While the fully-explicit form is efficient for steady state problems, due to its ability to handle localtime stepping, the quasi-implicit is the best choice for transient flow calculations with time independent boundary conditions. The semi-implicit form, with its stability restrictions, is the least favoured of all the three forms for incompressible flow calculations

Experimental Implementation of Discrete Time Quantum Random Walk on an NMR Quantum Information Processor

We present an experimental implementation of the coined discrete time quantum walk on a square using a three qubit liquid state nuclear magnetic resonance (NMR) quantum information processor (QIP). Contrary to its classical counterpart, we observe complete interference after certain steps and a periodicity in the evolution. Complete state tomography has been performed for each of the eight steps making a full period. The results have extremely high fidelity with the expected states and show clearly the effects of quantum interference in the walk. We also show and discuss the importance of choosing a molecule with a natural Hamiltonian well suited to NMR QIP by implementing the same algorithm on a second molecule. Finally, we show experimentally that decoherence after each step makes the statistics of the quantum walk tend to that of the classical random walk.Comment: revtex4, 8 pages, 6 figures, submitted to PR