Fluiddynamik des Kammerwassers beim chronischen einfachen Glaukom: Mechanismen der Drucknormalisierung durch ein künstliches Abflusssystem

Zusammenfassung: Die Wechselwirkung zwischen Kräften, Verteilung und Absorption des Kammerwassers im subkonjunktivalen Gewebe wird anhand eines kürzlich publizierten theoretischen Modells untersucht, das die Produktion von Flüssigkeit im Auge und deren Eliminierung durch das Trabekelwerk, das uveosklerale Gewebe und einen Shunt beschreibt. Zielgröße dabei ist der intraokulare Druck. Die Mechanismen von neu geschaffenen Abflusswegen werden mithilfe der Theorie der porösen Medien dargestellt, die sich auf ein Sickerkissen beziehen, das unter dem subkonjunktivalen Gewebe liegt. Die rechnerische Analyse basiert auf der Geometrie und den Parametern, die das Zu- und Abflusssystem charakterisieren. Diese sind durch die Produktion von Kammerwasser, den chirurgisch angelegten Abflusskanal, sodann durch die Resorption in den episkleralen Gefäßen und durch die hydraulischen Eigenschaften des subkonjunktivalen Gewebes und des Sickerkissens sowie durch dessen Geometrie gegeben. Anhand parametrischer Untersuchungen können klinische Befunde physikalisch begründet werde

Structure and activity relationships for amine-based CO2 absorbents-II

A study to determine the structure and activity relationships of various amine-based CO2 absorbents was performed, in which the absorption of pure CO2 at atmospheric pressure was measured to assess the total absorption rates and capacities. Steric hindrance effect was noticed when side chain with alkyl group was present at the α-carbon to the amine group in the absorbent structure. An increase in the number of amine groups in absorbent structure, results in a higher capacity of upto 3.03 moles CO2/moles amine. Aromatic amines substituted with alkyl groups at the 2nd and 5th position show an increase in both absorption rate and capacity. © 2008 The Institution of Chemical Engineers

What type of faculty member interacts with what type of firm? Some reasons for the delocalisation of university-industry interaction

33 pages, 6 tables.While there is significant interest in improving university-industry interaction, literature on the university side has tended not to focus on the characteristics of the personnel involved and has largely ignored the issue that there are differences between types of faculty member in their degrees of interaction. This question is especially relevant at regional level, as those faculty members who do interact with industry may show a preference for firms that are larger and technologically superior to those in the region. Most analysts, though, have tended to focus on the national level, particularly on those countries at the forefront of technological innovation. In the absence of any formal theory, we propose a two-step method to formulate the hypothesis that only selected faculty members interact with selected firms. First, we identify the type of faculty member who interacts with firms. Second, we examine whether this type of faculty member interacts with every type of firm. A test sample is drawn from the Valencian Community of Spain, a region with low absorptive capacity, where firms may show undesirable properties for university interaction. The results allow us to challenge the view that certain individual universities may show a higher propensity for interaction once we take into account differences between the individual characteristics of their faculty members. We also claim that in a region like the Valencian Community, faculty members who usually participate in contracts (male, holding an administrative position) do so mainly with larger firms, but not with firms from their own region, where they find lower technological standards. This partly explains the delocalisation of university-industry interaction.I wish to express my gratitude to the Valencian High Consultancy Council in R&D, for providing the funds to carry out this research.Peer reviewe

The architecture of the left ventricular myocytes relative to left ventricular systolic function

Objective: Mural thickening, combined with longitudinal and circumferential shortening, and apical along with basal twisting are critical components of the left ventricular systolic deformation that contribute to ventricular ejection. It is axiomatic that the spatial alignment of the actively contracting aggregates of myocytes must play a major role in the resulting ventricular deformation. The need to conserve functional global myocytic architecture, therefore, is an important aspect of the surgical manoeuvres affecting ventricular mass and geometry. To investigate the influence of the global alignment of the myocytes on ventricular contraction, we used a mathematical model simulating the large deformations produced by systolic contraction of the left ventricle of a human heart. Methods: The alignment and meshing of the myocytes within their supporting fibrous matrix cause mechanical anisotropy, which was included in the mathematical model in the form of a unit vector field, constructed from the measured trajectories of aggregated myocytes in an autopsied human heart. The relationship between ventricular structure and ventricular dynamics was assessed by analysing the influence of systematic deviations of the orientation of the myocytes from their original alignment, in longitudinal as well as radial directions, on the distribution of stress and strain within the myocardium, as well as on the ejection fraction. In addition, simplified idealised geometries were used to investigate the influence of the overall geometrical modifications. Results: Left ventricular function proved to be robust with respect to small-to-moderate rotational variations in myocytic alignment, up to 14°, a finding which we attribute to an equalising effect of the non-uniform anisotropic pattern found in a real heart involving substantial local irregularities in the architecture of the aggregated myocytes. Severe deterioration of function occurred only when deviations in alignment exceeded 30°. Conclusions: Our findings substantiate the concept of the myocardial walls representing a continuous three-dimensional meshwork, with the absence of any intermediate structures such as discrete bands or tracts extending over the ventricles, which could be destroyed surgically, thereby adversely affecting systolic function. With appropriate indications, they also support the validity of the surgical procedures performed to reduce ventricular radius and therefore to reduce mural stres

Representations of the discrete inhomogeneous Lorentz group and Dirac wave equation on the lattice

We propose the fundamental and two dimensional representation of the Lorentz groups on a (3+1)-dimensional hypercubic lattice, from which representations of higher dimensions can be constructed. For the unitary representation of the discrete translation group we use the kernel of the Fourier transform. From the Dirac representation of the Lorentz group (including reflections) we derive in a natural way the wave equation on the lattice for spin 1/2 particles. Finally the induced representation of the discrete inhomogeneous Lorentz group is constructed by standard methods and its connection with the continuous case is discussed.Comment: LaTeX, 20 pages, 1 eps figure, uses iopconf.sty (late submission

SO(2,1) conformal anomaly: Beyond contact interactions

The existence of anomalous symmetry-breaking solutions of the SO(2,1) commutator algebra is explicitly extended beyond the case of scale-invariant contact interactions. In particular, the failure of the conservation laws of the dilation and special conformal charges is displayed for the two-dimensional inverse square potential. As a consequence, this anomaly appears to be a generic feature of conformal quantum mechanics and not merely an artifact of contact interactions. Moreover, a renormalization procedure traces the emergence of this conformal anomaly to the ultraviolet sector of the theory, within which lies the apparent singularity.Comment: 11 pages. A few typos corrected in the final versio