Secondary zoospores in the algal endoparasite Maullinia ectocarpii (Plasmodiophorea).

The present paper deals with the ultrastructure of zoospores produced by the plasmodiophorid Maullinia ectocarpii , living in the marine algal host Ectocarpus siliculosus. The zoospores described here are very similar to secondary zoospores of Polymyxa graminis and Phagomyxa sp. (the latter an algal endopara- site, also). Our results indicate that M. ectocarpii produces two types of plasmodia, and suggest that is a species with a complete life cycle, as it is known for all the Plasmodiophormycota that have been studied. Sporogenic and sporangial plasmodia produce, respectively, primary zoospores with parallel flagella within thick walled resting sporangia, and secondary zoospores with opposite flagella within thin walled sporangia.Fil: Parodi, Elisa Rosalia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur; ArgentinaFil: Caceres, Eduardo Jorge. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Laboratorio de Ficología y Micología; ArgentinaFil: Westermeier, Renato. Universidad Austral de Chile; ChileFil: Muller, Dieter G.. Universität Konstanz; Alemani

Measuring the vulnerability for classes of intersection graphs

AbstractA general method for the computation of various parameters measuring the vulnerability of a graph is introduced. Four measures of vulnerability are considered, i.e., the toughness, scattering number, vertex integrity and the size of a minimum balanced separator. We show how to compute these parameters by polynomial-time algorithms for various classes of intersection graphs like permutation graphs, bounded dimensional cocomparability graphs, interval graphs, trapezoid graphs and circular versions of these graph classes

Some ideas about electrochemical characterization of dental alloys

Extensions and modifications of standard electrochemical techniques, accounting for unique conditions related to biological considerations, have proved useful in attacking some problems related to biocompatibility of the Biomaterial. Some authors have demonstrated that modern electrochemical techniques can be used to clarify some difficult problems in the field of biomaterials. Precious alloys can not be apply for all cases especially such as long range bridges or prostheses. For this reason, Ni-Cr as well as Co-Cr casting alloys have been used for dental application as alternatives to precious alloys. The biocompatibility of Ni-Cr alloys have been questioned because of their corrosive, allergenic, and even mutagenic potentials. The nature of passive films on metals and alloys is the ultimate factor which controls their corrosion behavior. There is little reliable information on the effects of the physical and chemical factors involved in the tissue response to an implant and the associated ionic release on the cellmaterial interaction. Depending of the casting process during the production of a dental prosthesis, these alloys may show different phases, ones may be more stable than other. For this reason, the development of a quick and simple method for determining the corrosion behavior as a control test in the production Biomecánica, 9 (1), 2001, pp. 66-70 67 of a dental prosthesis is of great interest. The purpose of this work was to show some results on the corrosion behavior of two different commercial alloys: Wiron 99 ( Ni-Cr alloy) and Aurolloyd kf (Au alloy). These results were obtained by several electrochemical methods: Open Circuit Potential vs time and Liner Sweep Voltammetry for Wiron 99, and Open Circuit Potential vs time and Cyclic Voltammetry for Aurolloyd kf. In the case of the Ni-Cr alloys, it is concluded that with the combination of both methods, it is possible to know how the corrosion behavior of casting individual dental Ni-Cr alloy prosthesis is, and in the case of Au alloy, it is concluded that the differences in electrochemical behavior strongly depend of surface oxides formed. These results showed that one of the studied combination, Eoc-Rp or Eoc-CV characterization, could be selected as control test after casting of individual prosthesis.Peer Reviewe

New aesthetic, new anxieties

The New Aesthetic was a design concept and netculture phenomenon launched into the world by London designer James Bridle in 2011. It continues to attract the attention of media art, and throw up associations to a variety of situated practices, including speculative design, net criticism, hacking, free and open source software development, locative media, sustainable hardware and so on. In this book we consider the New Aesthetic: as an opportunity to rethink the relations between these contexts in the emergent episteme of computationality. There is a desperate need to confront the political pressures of neoliberalism manifested in these infrastructures. Indeed, these are risky, dangerous and problematic times; a period when critique should thrive. But here we need to forge new alliances, invent and discover problems of the common that nevertheless do not eliminate the fundamental differences in this ecology of practices. In this book, perhaps provocatively, we believe a great deal could be learned from the development of the New Aesthetic not only as a mood, but as a topic and fix for collective feeling, that temporarily mobilizes networks. Is it possible to sustain and capture these atmospheres of debate and discussion beyond knee-jerk reactions and opportunistic self-promotion? These are crucial questions that the New Aesthetic invites us to consider, if only to keep a critical network culture in place

Electron localization by self-assembled GaSb/GaAs quantum dots.

We have studied the photoluminescence from type-II GaSb/GaAs self-assembled quantum dots in magnetic fields up to 50 T. Our results show that at low laser power, electrons are more weakly bound to the dots than to the wetting layer, but that at high laser power, the situation is reversed. We attribute this effect to an enhanced Coulomb interaction between a single electron and dots that are multiply charged with holes

Development of a synergy audit model for sustainability of horizontal airline alliances

Thesis (PhD)--Stellenbosch University, 2003.ENGLISH ABSTRACT: For more than a decade there has been an economic need to mitigate the negative effects of the air transport industry's innate sensitivity to cyclical developments as well as the effects of its inherent lack of substantial profits. The past 20 years were additionally marked by a change in policy that prompted various countries to liberalise and privatise their civil passenger air transportation industry. At the same time, airlines' business ambitions became more global, tapping into markets beyond countries' or continents' main gateways. All three aspects started to change the pattern of airline competition and required new business models. Key features of airlines' novel business models are geographic expansion and thus market development. Global expansion strategies and market development activities in passenger air transportation are, however, not easily and fluidly executable. The airline industry is, to some extent, still nationally regulated, thus impeding passenger airlines from fully participating in the global market-scene and from freely entering promising geographies. Concomitantly, the competitive landscape in which scheduled passenger airlines operate changed drastically, with travel value chains occasionally undergoing revolutionary transformations on both the supply and the demand side. Finally, the air transport service reveals several peculiarities that impact its production, distribution and consummation. These characteristics have inspired the execution of novel forms of competitive strategies that are described and critically discussed in this dissertation. Within this context, a main root cause for passenger airline partnerships appears to be its continued regulation and the circumvention thereof through the horizontal joining of forces, thus emulating concentration tendencies that have long been a fixture in other globalising industries. Consequently, horizontal interairline partnerships were induced and identified as a key competitive device with which to weather the challenges of the new air transport rivalry structures, the increasingly deregulated environment, and the impediments of sustained market regulation. All major airlines are now involved in some type of horizontal collaboration. The spectrum of these linkages is wide and ranges from loose, unattached, operative agreements to long-term, far-reaching, strategic ones, the most salient forms and instruments of which are thoroughly scrutinised in this dissertation. This dissertation additionally presents the general core inducing economic drivers of carrier interrelationship, which are cost reduction, revenue generation and corporate power considerations. While these aspects offer a multitude of possible partnership forms and instruments, the bulk of airline linkages, however, is presently constituted of joint revenue generation and, consequently, jointly pursued marketing and market expansion goals. In view of these causes, the present dissertation engages in a profound discussion of the rationales behind interairline partnerships, their likely evolution and effects on management practice. Essentially, the key importance of airline partnerships in meeting basic economic imperatives on the one hand, while circumventing persistent regulation on the other, questions the sustainability of incumbent carriers' current business models. There are clear indications that a structured sequence of events in establishing interairline linkages is a key success factor for horizontal airline partnerships. However, the empirical examination of contemporary partnerships' governance structures and managerial practice strongly points to a lack of ample tools with which to establish airline partnerships, select the appropriate match between alliance goals and intensity, and govern alliances during their entire life-cycles. This drawback seems particularly unacceptable in view of the urgent requirement for more appropriate managerial practice in today's discontinuous air transport business environment, and speaks loudly of the need for a framework with which to enhance airline partnership output. Most ideally, a coherent, structured sequence of events should be followed in partnership formation, organisational set-up and management in order to bring an alliance to fruition. On this basis, the establishment of a collaboration governance organisation, adequately mirroring the specific partnership type and meeting the specific demands of all partners involved, is equally identified and described as a fundamental success driver in this dissertation. Further structural, organisational and functional issues thereafter need to be considered in order to transform the joint business venture of two horizontally allied carriers into a venture for mutual success. The most essential of these are introduced in this dissertation. Synergy plays a central role in this context. Synergy, as the overreaching intention and result of working together towards a common goal, must be anchored as a prime objective of all forms of partnership activities. Synergy through interfirm linkages can be derived from various collaborative areas and is greatly influenced by both internal and external factors. One gauge for synergy, in particular for the transformation of synergy potentials into synergy effects, is partnership intensity. The measurement of partnership intensity can be used to perpetually monitor the benefits of partnership activities. At the same time, inconsistent or uneven partnership intensity can indicate the existence of dissynergies or frailties in the alliance. The underlying theories of collaborative synergy generation, its main drivers and impediments, with particular reference to horizontal partnerships of scheduled passenger airlines, are explored in this dissertation. In recognition of the theoretical and practical background of airline partnerships and the acknowledged problems associated with their establishment and operation, the present dissertation proposes a novel model dynamically supporting the quest for synergy in airline interrelationships. Incorporating the goals of synergy generation and its continual measurement in interairline partnerships, the synergy audit is designed as a dynamic managerial tool. The synergy audit functions as a recurring device for unleashing all the positive partnership benefits of collaborative scope and width. It aids airline alliance management in transforming the desired benefits of partnership activities - synergy potentials - into real, tangible synergy effects during the entire partnership life cycle. The tool A.PIE (Airline Partnership Intensity Evaluator) supports the synergy audit and, which idiosyncratic to the airline industry, multidimensionally applies the deduced relationship of partnership intensity and synergy to the most salient partnership areas and functions. The present dissertation shapes understanding of the true drivers and complexities of today's airline partnerships. It proposes a circular, multidimensional and dynamic model, thus attempting to enhance the set-up, performance and output of horizontal airline collaboration. From this point of view it endeavours to fill the gap identified in contemporary airline partnership management and practice.AFRIKAANSE OPSOMMING: Sien asb volteks vir opsommin

Cosmological String Backgrounds from Gauged WZW Models

We discuss the four-dimensional target-space interpretation of bosonic strings based on gauged WZW models, in particular of those based on the non-compact coset space $SL(2,{\bf R})\times SO(1,1)^2 /SO(1,1)$. We show that these theories lead, apart from the recently broadly discussed black-hole type of backgrounds, to cosmological string backgrounds, such as an expanding Universe. Which of the two cases is realized depends on the sign of the level of the corresponding Kac-Moody algebra. We discuss various aspects of these new cosmological string backgrounds.Comment: 11 page

Prospective randomized controlled trial of simulator-based versus traditional in-surgery laparoscopic camera navigation training

Background: Surgical residents often use a laparoscopic camera in minimally invasive surgery for the first time in the operating room (OR) with no previous education or experience. Computer-based simulator training is increasingly used in residency programs. However, no randomized controlled study has compared the effect of simulator-based versus the traditional OR-based training of camera navigation skills. Methods: This prospective randomized controlled study included 24 pregraduation medical students without any experience in camera navigation or simulators. After a baseline camera navigation test in the OR, participants were randomized to six structured simulator-based training sessions in the skills lab (SL group) or to the traditional training in the OR navigating the camera during six laparoscopic interventions (OR group). After training, the camera test was repeated. Videos of all tests (including of 14 experts) were rated by five blinded, independent experts according to a structured protocol. Results: The groups were well randomized and comparable. Both training groups significantly improved their camera navigational skills in regard to time to completion of the camera test (SL P=0.049; OR P=0.02) and correct organ visualization (P=0.04; P=0.03). Horizon alignment improved without reaching statistical significance (P=0.20; P=0.09). Although both groups spent an equal amount of actual time on camera navigation training (217 vs. 272min, P=0.20), the SL group spent significantly less overall time in the skill lab than the OR group spent in the operating room (302 vs. 1002min, P<0.01). Conclusion: This is the first prospective randomized controlled study indicating that simulator-based training of camera navigation can be transferred to the OR using the traditional hands-on training as controls. In addition, simulator camera navigation training for laparoscopic surgery is as effective but more time efficient than traditional teachin

Institutional factors governing the deployment of remote experiments: lessons from the rexnet project

Remote labs offer many unique advantages to students as they provide opportunities to access experiments and learning scenarios that would be otherwise unavailable. At the same time, however, these opportunities introduce real challenges to the institutions hosting the remote labs. This paper draws on the experiences of the REXNET project consortium to expose a number of these issues as a means of furthering the debate on the value of remote labs and the best practices in deploying them. The paper presents a brief outline of the various types of remote lab scenarios that might be deployed. It then describes the key human and technological actors that have an interest in or are intrinsic to a remote lab instance, with a description of the role of each actor and their interest. Some relationships between these various actors are then discussed with some factors that might influence those relationships. Finally some general issues are briefly described

Evaluating Depressive Symptoms in Schizophrenia: A Psychometric Comparison of the Calgary Depression Scale for Schizophrenia and the Hamilton Depression Rating Scale

Background: The aim of this study was to compare two measures of depression in patients with schizophrenia and schizophrenia spectrum disorder, including patients with delusional and schizoaffective disorder, to conclude implications for their application. Sampling and Methods: A total of 278 patients were assessed using the Calgary Depression Scale for Schizophrenia (CDSS) and the Hamilton Depression Rating Scale (HAMD-17). The Positive and Negative Syndrome Scale (PANSS) was also applied. At admission and discharge, a principal component analysis was performed with each depression scale. The two depression rating scales were furthermore compared using correlation and regression analyses. Results: Three factors were revealed for the CDSS and HAMD-17 factor component analysis. A very similar item loading was found for the CDSS at admission and discharge, whereas results of the loadings of the HAMD-17 items were less stable. The first two factors of the CDSS revealed correlations with positive, negative and general psychopathology. In contrast, multiple significant correlations were found for the HAMD-17 factors and the PANSS sub-scores. Multiple regression analyses demonstrated that the HAMD-17 accounted more for the positive and negative symptom domains than the CDSS. Conclusions:The present results suggest that compared to the HAMD-17, the CDSS is a more specific instrument to measure depressive symptoms in schizophrenia and schizophrenia spectrum disorder, especially in acutely ill patients. Copyright (c) 2012 S. Karger AG, Base