Showing papers by "University of Vienna published in 2001"

Introduction to Numerical Analysis

Abstract: Numerical analysis is an increasingly important link between pure mathematics and its application in science and technology. This textbook provides an introduction to the justification and development of constructive methods that provide sufficiently accurate approximations to the solution of numerical problems, and the analysis of the influence that errors in data, finite-precision calculations, and approximation formulas have on results, problem formulation and the choice of method. It also serves as an introduction to scientific programming in MATLAB, including many simple and difficult, theoretical and computational exercises. A unique feature of this book is the consequent development of interval analysis as a tool for rigorous computation and computer assisted proofs, along with the traditional material.

Entanglement of the orbital angular momentum states of photons

Abstract: Entangled quantum states are not separable, regardless of the spatial separation of their components This is a manifestation of an aspect of quantum mechanics known as quantum non-locality An important consequence of this is that the measurement of the state of one particle in a two-particle entangled state defines the state of the second particle instantaneously, whereas neither particle possesses its own well-defined state before the measurement Experimental realizations of entanglement have hitherto been restricted to two-state quantum systems, involving, for example, the two orthogonal polarization states of photons Here we demonstrate entanglement involving the spatial modes of the electromagnetic field carrying orbital angular momentum As these modes can be used to define an infinitely dimensional discrete Hilbert space, this approach provides a practical route to entanglement that involves many orthogonal quantum states, rather than just two Multi-dimensional entangled states could be of considerable importance in the field of quantum information, enabling, for example, more efficient use of communication channels in quantum cryptography

Closing A Conceptual Gap: The Case For A Description Of English As A Lingua Franca

Abstract: Despite momentous developments in the sociopolitics of the teaching of English worldwide, targets have generally remained tied to nativespeaker norms. This paper argues that although this orientation is often recognized as inappropriate and counter-productive, it persists because discussions about ‘global English’ on the meta-level have not been accompanied by a necessary reorientation in linguistic research: very little empirical work has so far been done on the most extensive contemporary use of English worldwide, namely English as a lingua franca, largely among ‘non-native’ speakers. The paper seeks to demonstrate that this lack of a descriptive reality precludes us from conceiving of speakers of lingua franca English as language users in their own right and thus makes it difficult to counteract the reproduction of native English dominance. To remedy this situation, a research agenda is proposed which accords lingua franca English a central place in description alongside English as a native language, and a new corpus project is described which constitutes a first step in this process. The paper concludes with a consideration of the potentially very significant impact that the availability of an alternative model for the teaching of English as a lingua franca would have for pedagogy and teacher education.

The Effect of Green Investment on Corporate Behavior

Abstract: This paper explores the effect of exclusionary ethical investing on corporate behavior in a risk-averse, equilibrium setting. While arguments exist that ethical investing can influence a firm's cost of capital, and so affect investment, no equilibrium model has been presented to do so. We show that exclusionary ethical investing leads to polluting firms being held by fewer investors since green investors eschew polluting firms' stock. This lack of risk sharing among non-green investors leads to lower stock prices for polluting firms, thus raising their cost of capital. If the higher cost of capital more than overcomes a cost of reforming (i.e., a polluting firm cleaning up its activities), then polluting firms will become socially responsible because of exclusionary ethical investing. A key determinant of the incentive for polluting firms to reform is the fraction of funds controlled by green investors. In our model, empirically reasonable parameter estimates indicate, that more than 20 % green investors are required to induce any polluting firmss to reform. Existing empirical evidence indicates that at most 10% of funds are invested by green investors.

Isolated lymphatic endothelial cells transduce growth, survival and migratory signals via the VEGF‐C/D receptor VEGFR‐3

Abstract: Vascular endothelial growth factor receptor-3 (VEGFR-3/Flt4) binds two known members of the VEGF ligand family, VEGF-C and VEGF-D, and has a critical function in the remodelling of the primary capillary vasculature of midgestation embryos. Later during development, VEGFR-3 regulates the growth and maintenance of the lymphatic vessels. In the present study, we have isolated and cultured stable lineages of blood vascular and lymphatic endothelial cells from human primary microvascular endothelium by using antibodies against the extracellular domain of VEGFR-3. We show that VEGFR-3 stimulation alone protects the lymphatic endothelial cells from serum deprivation-induced apoptosis and induces their growth and migration. At least some of these signals are transduced via a protein kinase C-dependent activation of the p42/p44 MAPK signalling cascade and via a wortmannin-sensitive induction of Akt phosphorylation. These results define the critical role of VEGF-C/VEGFR-3 signalling in the growth and survival of lymphatic endothelial cells. The culture of isolated lymphatic endothelial cells should now allow further studies of the molecular properties of these cells.

Different behavior of branched and linear polyethylenimine for gene delivery in vitro and in vivo.

Abstract: Background Efficient gene transfer is a major challenge for non-viral gene therapy. Understanding how non-viral vectors initiate gene expression could lead to the development of new future vectors with enhanced efficacy. Methods Linear or branched polyethylenimine (PEI)/DNA complexes were generated in varying salt conditions and their transfection efficiencies were compared in vitro and in vivo using reporter genes, luciferase and green fluorescent protein, and rhodamine labeled DNA (pGeneGrip™). Results The transfection efficiency of linear PEI22/DNA in vitro was generally greater than that of branched PEI/DNA when complexes were generated in salt containing buffer. However, PEI complexes generated under salt-free conditions generally had low transfection activity in vitro. In contrast, PEI22/DNA salt-free complexes were highly active in vivo. Branched PEI/DNA and salt containing PEI22/DNA complexes were generally 10–100-fold less active than the salt-free PEI22/DNA complexes. Salt-free PEI22/DNA complexes were small, but subsequently grew into aggregates when salt was added. In contrast, PEI25/DNA complexes remained small even after salt was added under the same conditions. Furthermore, PEI22/pGeneGrip™ complexes formed large aggregates associated with the cell membrane, cytoplasm and nucleus, while branched PEI complexes remained as small distinct particles associated with the cell membrane or in the cytoplasm. Conclusions Branched and linear PEI/DNA complexes differ in their ability to transfect cells. The greater efficiency of linear PEI might be due to an inherent kinetic instability under salt conditions. Understanding how to employ this kinetic instability of linear PEI could help in designing future vectors with greater flexibility and transfection efficiency in vivo. Copyright © 2001 John Wiley & Sons, Ltd.

The autophagosomal-lysosomal compartment in programmed cell death.

Abstract: In the last decade a tremendous progress has been achieved in understanding the control of apoptosis by survival and death factors as well as the molecular mechanisms of preparation and execution of the cell's suicide. However, accumulating evidence suggests that programmed cell death (PCD) is not confined to apoptosis but that cells use different pathways for active self-destruction as reflected by different morphology: condensation prominent, type I or apoptosis; autophagy prominent, type II; etc. Autophagic PCD appears to be a phylogenetically old phenomenon, it may occur in physiological and disease states. Recently, distinct biochemical and molecular features have been be assigned to this type of PCD. However, autophagic and apoptotic PCD should not be considered as mutually exclusive phenomena. Rather, they appear to reflect a high degree of flexibility in a cell's response to changes of environmental conditions, both physiological or pathological. Furthermore, recent data suggest that diverse or relatively unspecific signals such as photodamage or lysosomotropic agents may be mediated by lysosomal cysteine proteases (cathepsins) to caspases and thus, apoptosis. The present paper reviews morphological, functional and biochemical/molecular data suggesting the participation of the autophagosomal-lysosomal compartment in programmed cell death.

Entanglement purification for quantum communication

Abstract: The distribution of entangled states between distant locations will be essential for the future large-scale realization of quantum communication schemes such as quantum cryptography1,2 and quantum teleportation3. Because of unavoidable noise in the quantum communication channel, the entanglement between two particles is more and more degraded the further they propagate. Entanglement purification4,5,6,7 is thus essential to distil highly entangled states from less entangled ones. Existing general purification protocols4,5,6 are based on the quantum controlled-NOT (CNOT) or similar quantum logic operations, which are very difficult to implement experimentally. Present realizations of CNOT gates are much too imperfect to be useful for long-distance quantum communication8. Here we present a scheme for the entanglement purification of general mixed entangled states, which achieves 50 per cent of the success probability of schemes based on the CNOT operation, but requires only simple linear optical elements. Because the perfection of such elements is very high, the local operations necessary for purification can be performed with the required precision. Our procedure is within the reach of current technology, and should significantly simplify the implementation of long-distance quantum communication.

Reward and punishment

Abstract: Minigames capturing the essence of Public Goods experiments show that even in the absence of rationality assumptions, both punishment and reward will fail to bring about prosocial behavior. This result holds in particular for the well-known Ultimatum Game, which emerges as a special case. But reputation can induce fairness and cooperation in populations adapting through learning or imitation. Indeed, the inclusion of reputation effects in the corresponding dynamical models leads to the evolution of economically productive behavior, with agents contributing to the public good and either punishing those who do not or rewarding those who do. Reward and punishment correspond to two types of bifurcation with intriguing complementarity. The analysis suggests that reputation is essential for fostering social behavior among selfish agents, and that it is considerably more effective with punishment than with reward.

Isolation and Characterization of Dermal Lymphatic and Blood Endothelial Cells Reveal Stable and Functionally Specialized Cell Lineages

Abstract: A plexus of lymphatic vessels guides interstitial fluid, passenger leukocytes, and tumor cells toward regional lymph nodes Microvascular endothelial cells (ECs) of lymph channels (LECs) are difficult to distinguish from those of blood vessels (BECs) because both express a similar set of markers, such as CD31, CD34, podocalyxin, von Willebrand factor (vWF), etc Analysis of the specific properties of LECs was hampered so far by lack of tools to isolate LECs Recently, the 38-kD mucoprotein podoplanin was found to be expressed by microvascular LECs but not BECs in vivo Here we isolated for the first time podoplanin+ LECs and podoplanin− BECs from dermal cell suspensions by multicolor flow cytometry Both EC types were propagated and stably expressed VE-cadherin, CD31, and vWF Molecules selectively displayed by LECs in vivo, ie, podoplanin, the hyaluronate receptor LYVE-1, and the vascular endothelial cell growth factor (VEGF)-C receptor, fms-like tyrosine kinase 4 (Flt-4)/VEGFR-3, were strongly expressed by expanded LECs, but not BECs Conversely, BECs but not LECs expressed VEGF-C LECs as well as BECs formed junctional contacts with similar molecular composition and ultrastructural features Nevertheless, the two EC types assembled in vitro in vascular tubes in a strictly homotypic fashion This EC specialization extends to the secretion of biologically relevant chemotactic factors: LECs, but not BECs, constitutively secrete the CC chemokine receptor (CCR)7 ligand secondary lymphoid tissue chemokine (SLC)/CCL21 at their basal side, while both subsets, upon activation, release macrophage inflammatory protein (MIP)-3α/CCL20 apically These results demonstrate that LECs and BECs constitute stable and specialized EC lineages equipped with the potential to navigate leukocytes and, perhaps also, tumor cells into and out of the tissues

Measurement and imaging of birefringence and optic axis orientation by phase resolved polarization sensitive optical coherence tomography

Abstract: We present an improved method of polarization sensitive optical coherence tomography that enables measurement and imaging of backscattered intensity, birefringence, and fast optic axis orientation simultaneously with only one single A-scan per transverse measurement location. While intensity and birefringence data are obtained in a conventional way, the optic axis orientation is determined from the phase difference recorded in two orthogonal polarization channels. We report on accuracy and precision of the method by measuring birefringence and optic axis orientation of well defined polarization states in a technical object and present maps of birefringence and, what we believe for the first time, of optic axis orientation in biological tissue.

On convex sobolev inequalities and the rate of convergence to equilibrium for fokker-planck type equations

Abstract: It is well known that the analysis of the large-time asymptotics of Fokker-Planck type equations by the entropy method is closely related to proving the validity of convex Sobolev inequalities. Here we highlight this connection from an applied PDE point of view. In our unified presentation of the theory we present new results to the following topics: an elementary derivation of Bakry-Emery type conditions, results concerning perturbations of invariant measures with general admissible entropies, sharpness of convex Sobolev inequalities, applications to non-symmetric linear and certain non-linear Fokker-Planck type equations (Desai-Zwanzig model, drift-diffusion-Poisson model).

Advanced determinant calculus

Abstract: The purpose of this article is threefold. First, it provides the reader with a few useful and efficient tools which should enable her/him to evaluate nontrivial determinants for the case such a determinant should appear in her/his research. Second, it lists a number of such determinants that have been already evaluated, together with explanations which tell in which contexts they have appeared. Third, it points out references where further such determinant evaluations can be found.

Hyperthermia After Cardiac Arrest Is Associated With an Unfavorable Neurologic Outcome

Abstract: Background Moderate elevation of brain temperature, when present during or after ischemia, may markedly worsen the resulting injury. Objective To evaluate the impact of body temperature on neurologic outcome after successful cardiopulmonary resuscitation. Methods In patients who experienced a witnessed cardiac arrest of presumed cardiac cause, the temperature was recorded on admission to the emergency department and after 2, 4, 6, 12, 18, 24, 36, and 48 hours. The lowest temperature within 4 hours and the highest temperature during the first 48 hours after restoration of spontaneous circulation were recorded and correlated to the best-achieved cerebral performance categories' score within 6 months. Results Over 43 months, of 698 patients, 151 were included. The median age was 60 years (interquartile range, 53-69 years); the estimated median no-flow duration was 5 minutes (interquartile range, 0-10 minutes), and the estimated median low-flow duration was 14.5 minutes (interquartile range, 3-25 minutes). Forty-two patients (28%) underwent bystander-administered basic life support. Within 6 months, 74 patients (49%) had a favorable functional neurologic recovery, and a total of 86 patients (57%) survived until 6 months after the event. The temperature on admission showed no statistically significant difference (P =.39). Patients with a favorable neurologic recovery showed a higher lowest temperature within 4 hours (35.8 degrees C [35.0 degrees C-36.1 degrees C] vs 35.2 degrees C [34.5 degrees C-35.7 degrees C]; P =.002) and a lower highest temperature during the first 48 hours after restoration of spontaneous circulation (37.7 degrees C [36.9 degrees C-38.6 degrees C] vs 38.3 degrees C [37.8 degrees C-38.9 degrees C]; P Conclusion Hyperthermia is a potential factor for an unfavorable functional neurologic recovery after successful cardiopulmonary resuscitation.

Experimental Demonstration of Four-Photon Entanglement and High-Fidelity Teleportation

Abstract: We experimentally demonstrate observation of highly pure four-photon GHZ entanglement produced by parametric down-conversion and a projective measurement. At the same time this also demonstrates teleportation of entanglement with very high purity. Not only does the achieved high visibility enable various novel tests of quantum nonlocality, it also opens the possibility to experimentally investigate various quantum computation and communication schemes with linear optics. Our technique can, in principle, be used to produce entanglement of arbitrarily high order or, equivalently, teleportation and entanglement swapping over multiple stages.

Aged mother cells of Saccharomyces cerevisiae show markers of oxidative stress and apoptosis

Abstract: Recently, we and others have shown that genetic and environmental changes that increase the load of yeast cells with reactive oxygen species (ROS) lead to a shortening of the life span of yeast mother cells. Deletions of yeast genes coding for the superoxide dismutases or the catalases, as well as changes in atmospheric oxygen concentration, considerably shortened the life span. The presence of the physiological antioxidant glutathione, on the other hand, increased the life span of yeast cells. Taken together, these results pointed to a role for oxygen in the yeast ageing process. Here, we show by staining with dihydrorhodamine that old yeast mother cells isolated by elutriation, but not young cells, contain ROS that are localized in the mitochondria. A relatively large proportion of the old mother cells shows phenotypic markers of yeast apoptosis, i.e. TUNEL (TdT-mediated dUTP nick end labelling) and annexin V staining. Although it has been shown previously that apoptosis in yeast can be induced by a cdc48 allele, by expressing pro-apoptotic human cDNAs or by stressing the cells with hydrogen peroxide, we are now showing a physiological role for apoptosis in unstressed but aged wild-type yeast mother cells.

CYP2D6 and CYP2C19 genotype-based dose recommendations for antidepressants: a first step towards subpopulation-specific dosages.

Abstract: CYP2D6 and CYP2C19 genotype-based dose recommendations for antidepressants: A first step towards subpopulation specific dosages.

Entropy dissipation methods for degenerate parabolic problems and generalized Sobolev inequalities

Abstract: We analyse the large-time asymptotics of quasilinear (possibly) degenerate parabolic systems in three cases: 1) scalar problems with confinement by a uniformly convex potential, 2) unconfined scalar equations and 3) unconfined systems. In particular we are interested in the rate of decay to equilibrium or self-similar solutions. The main analytical tool is based on the analysis of the entropy dissipation. In the scalar case this is done by proving decay of the entropy dissipation rate and bootstrapping back to show convergence of the relative entropy to zero. As by-product, this approach gives generalized Sobolev-inequalities, which interpolate between the Gross logarithmic Sobolev inequality and the classical Sobolev inequality. The time decay of the solutions of the degenerate systems is analyzed by means of a generalisation of the Nash inequality. Porous media, fast diffusion, p-Laplace and energy transport systems are included in the considered class of problems. A generalized Csiszar–Kullback inequality allows for an estimation of the decay to equilibrium in terms of the relative entropy.

National Labour Relations in Internationalized Markets: A Comparative Study of Institutions, Change, and Performance

Abstract: Presents and examines evidence and theories about changing patterns of industrial relations and their links to convergence on the one hand, and economic competitiveness on the other. Includes a comprehensive set of comparable date on industrial relations in twenty OECD countries including Australia, the United States, Canada, Japan, and most leading European countries.

Whole-body vibration exercise leads to alterations in muscle blood volume.

Abstract: Occupationally used high-frequency vibration is supposed to have negative effects on blood flow and muscle strength. Conversely, low-frequency vibration used as a training tool appears to increase muscle strength, but nothing is known about its effects on peripheral circulation. The aim of this investigation was to quantify alterations in muscle blood volume after whole muscle vibration--after exercising on the training device Galileo 2000 (Novotec GmbH, Pforzheim, Germany). Twenty healthy adults performed a 9-min standing test. They stood with both feet on a platform, producing oscillating mechanical vibrations of 26 Hz. Alterations in muscle blood volume of the quadriceps and gastrocnemius muscles were assessed with power Doppler sonography and arterial blood flow of the popliteal artery with a Doppler ultrasound machine. Measurements were performed before and immediately after exercising. Power Doppler indices indicative of muscular blood circulation in the calf and thigh significantly increased after exercise. The mean blood flow velocity in the popliteal artery increased from 6.5 to 13.0 cm x s(-1) and its resistive index was significantly reduced. The results indicate that low-frequency vibration does not have the negative effects on peripheral circulation known from occupational high-frequency vibration.

Is transurethral resection of the prostate still justified

Abstract: (WW) to holmium-laser resection (Table 1). RCTs with Introduction a follow-up of <6 months and with a substantial number of patients in urinary retention preoperatively were For decades TURP was the undisputed gold standard of therapy for patients with LUTS due to BPH; however, excluded. within the past 10 years this role has increasingly been challenged by the development of medical (5a reductase The current morbidity of TURP inhibitors, a1-receptor blockers) and less invasive interventional alternatives [1–8]. The main driving forces Mortality after TURP has decreased substantially during the past 30 years and is <0.25% in contemporary TURP behind this development were the high prevalence of the disease, an absolute indication for surgery in only 5–10% series [10–16]. Horninger et al. reported no postoperative deaths in a consecutive series of 1211 patients underof patients with symptomatic BPH, recent technical innovations and, most importantly, the apparently going TURP between 1988 and 1991 [16]. In the 29 RCTs reviewed, no patient died within the first 6 weeks unchanged high morbidity of TURP [9–16]. As a result, the number of prostatectomies decreased substantially after surgery, reflecting advances in anaesthesia achieved during the past two decades. [17,18], e.g. in the USA the number of TURPs for BPH was 253 000 within the US Medicare Program in 1987 The major intraoperative complication of TURP and fell to 145 000 in 1994, a reduction of 43% [17]. This trend is also demonstrable in Europe, although less Table 1 Pertinent characteristics of the 29 RCTs analysed pronounced in countries with very extensive public healthcare systems [18]. Enthusiastic reports on the No. of patients* in success of alternative treatment options in the lay and No. of urological press seemed to herald the end of TURP as Method studies Reference(s) TURP Control the gold standard, perhaps best reflected by Stamey’s Open 1 20 43 32 quote in 1993 that ‘TURP is now a therapy of history’ Prostatectomy [19]. TUIP 6 21–26† 285 270 The objective of this review is to determine the current TUVP 4 27–30 199 189 status of TURP with particular reference to less invasive Holmium Laser 1 31 11 23 procedures and recent developments of transurethral VLAP 7 32–38 351 416 electrosurgery. To reliably assess this issue, we reviewed ILC 2 39, 40 41 60 the recent urological literature and, specifically, all 29 TUNA 2 41, 42 107 117 TUMT 2.5 2 43, 44 61 61 randomized clinical trials (RCTs) published between IRFT 1 45 25 25 1986 and 1998 comparing less-invasive treatment TUMT 2.0 1 46 32 37 options directly with TURP (Table 1) [20–48]. These 29 BDP 2 26†, 47 45 46 RCTs contain clinical information for a total of 3032 WW 1 48 280 276 patients, 1480 being randomized to TURP, 1552 to lessTotal 29 148

Mating behavior and chemical communication in the order hymenoptera

Abstract: ▪ Abstract Insects of the order Hymenoptera are biologically and economically important members of natural and agro ecosystems and exhibit diverse biologies, mating systems, and sex pheromones. We review what is known of their sex pheromone chemistry and function, paying particular emphasis to the Hymenoptera Aculeata (primarily ants, bees, and sphecid and vespid wasps), and provide a framework for the functional classification of their sex pheromones. Sex pheromones often comprise multicomponent blends derived from numerous exocrine tissues, including the cuticle. However, very few sex pheromones have been definitively characterized using bioassays, in part because of the behavioral sophistication of many Aculeata. The relative importance of species isolation versus sexual selection in shaping sex pheromone evolution is still unclear. Many species appear to discriminate among mates at the level of individual or kin/colony, and they use antiaphrodisiacs. Some orchids use hymenopteran sex pheromones to dup...