99 research outputs found

    A handbook for the estimation of airside delays at major airports (quick approximation method)

    Get PDF
    The handbook contains a set of curves that allow estimation of the average number of total daily delay minutes at a major airport under a variety of conditions. Demand profiles at each airport are classified with respect to the number of daily peak periods, the percentage of daily flights during peak periods, and the number of peak period operations at the airport. When combined with the saturation capacity of the airport, these descriptors provide sufficient information to allow usage of the handbook. Examples illustrating the use of the handbook are provided, as well as a brief review and description of the technical approach and of the computer package developed for this purpose

    Potential impacts of advanced technologies on the ATC capacity of high-density terminal areas

    Get PDF
    Advanced technologies for airborne systems (automatic flight control, flight displays, navigation) and for ground ATC systems (digital communications, improved surveillance and tracking, automated decision-making) create the possibility of advanced ATC operations and procedures which can bring increased capacity for runway systems. A systematic analysis is carried out to identify certain such advanced ATC operations, and then to evaluate the potential benefits occurring over time at typical US high-density airports (Denver and Boston). The study is divided into three parts: (1) A Critical Examination of Factors Which Determine Operational Capacity of Runway Systems at Major Airports, is an intensive review of current US separation criteria and terminal area ATC operations. It identifies 11 new methods to increase the capacity of landings and takeoffs for runway systems; (2) Development of Risk Based Separation Criteria is the development of a rational structure for establishing reduced ATC separation criteria which meet a consistent Target Level of Safety using advanced technology and operational procedures; and (3) Estimation of Capacity Benefits from Advanced Terminal Area Operations - Denver and Boston, provides an estimate of the overall annual improvement in runway capacity which might be expected at Denver and Boston from using some of the advanced ATC procedures developed in Part 1. Whereas Boston achieved a substantial 37% increase, Denver only achieved a 4.7% increase in its overall annual capacity

    Identification and functional characterization of novel xylose transporters from the cell factories Aspergillus niger and Trichoderma reesei

    Get PDF
    Background: Global climate change and fossil fuels limitations have boosted the demand for robust and efficient microbial factories for the manufacturing of bio-based products from renewable feedstocks. In this regard, efforts have been done to enhance the enzyme-secreting ability of lignocellulose-degrading fungi, aiming to improve protein yields while taking advantage of their ability to use lignocellulosic feedstocks. Access to sugars in complex polysaccharides depends not only on their release by specific hydrolytic enzymes, but also on the presence of transporters capable of effectively transporting the constituent sugars into the cell. This study aims to identify and characterize xylose transporters from Aspergillus Niger and Trichoderma reesei, two fungi that have been industrially exploited for decades for the production of lignocellulose-degrading hydrolytic enzymes. Results: A hidden Markov model for the identification of xylose transporters was developed and used to analyze the A. Niger and T. reesei in silico proteomes, yielding a list of candidate xylose transporters. From this list, three A. Niger (XltA, XltB and XltC) and three T. reesei (Str1, Str2 and Str3) transporters were selected, functionally validated and biochemically characterized through their expression in a Saccharomyces cerevisiae hexose transport null mutant, engineered to be able to metabolize xylose but unable to transport this sugar. All six transporters were able to support growth of the engineered yeast on xylose but varied in affinities and efficiencies in the uptake of the pentose. Amino acid sequence analysis of the selected transporters showed the presence of specific residues and motifs recently associated to xylose transporters. Transcriptional analysis of A. Niger and T. reesei showed that XltA and Str1 were specifically induced by xylose and dependent on the XlnR/Xyr1 regulators, signifying a biological role for these transporters in xylose utilization. Conclusions: This study revealed the existence of a variety of xylose transporters in the cell factories A. Niger and T. reesei. The particular substrate specificity and biochemical properties displayed by A. Niger XltA and XltB suggested a possible biological role for these transporters in xylose uptake. New insights were also gained into the molecular mechanisms regulating the pentose utilization, at inducer uptake level, in these fungi. Analysis of the A. Niger and T. reesei predicted transportome with the newly developed hidden Markov model showed to be an efficient approach for the identification of new xylose transporting proteins.</p

    Evaluation of a prostate cancer e-health-tutorial

    Get PDF
    Hintergrund: Angesichts verschiedener Behandlungsoptionen ist die Information und Therapieentscheidung beim lokalisierten Prostatakarzinom eine Herausforderung. Die digitale Informationstechnologie bietet im Vergleich zu gedruckten Informationen mehr Möglichkeiten, die Information und die Patientenkommunikation bedarfsgerecht zu gestalten. Ziele: Zur Unterstützung der Therapieentscheidung und der Kommunikation mit Patienten ist in der deutschsprachigen Schweiz ein Online-Tutorial in einem systematischen Prozess entwickelt und in einer Pilotstudie getestet worden. In der Evaluation interessierten die Nutzerzufriedenheit, die Erfüllung der Informationsbedürfnisse, die Vorbereitung auf die Therapieentscheidung und deren subjektive Qualität. Material und Methoden: Die Plattform wurde in einem iterativen Prozess mittels Fokusgruppen mit Ärzten und Patienten auf der Grundlage von Informationen aus bestehenden Broschüren entwickelt. Für den Test der Plattform wurden in 8 urologischen Kliniken 87 Patienten zur Teilnahme eingeladen. Die 56 Nutzer wurden 4 Wochen nach dem Login und 3 Monate nach dem Therapieentscheid online befragt, 48 Nutzer füllten beide Befragungen aus. Eingesetzte Instrumente waren die Preparation for Decision Making Scale (PDMS), die Decisional Conflict Scale (DCS) und die Decisional Regret Scale (DRS). Ergebnisse und Diskussion: Die Nutzenden sind mit der Plattform sehr zufrieden und finden ihre Informationsbedürfnisse gut erfüllt. Sie zeigen 3 Monate nach dem Entscheid eine gute Vorbereitung auf die Entscheidung (MW PDMS 75, SD 23) und berichten über niedrigen Entscheidungskonflikt (MW DCS 9.6, SD 11) und kaum Bedauern über die Entscheidung (MW DRS 6.4, SD 9.6). Basierend auf diesen Erkenntnissen kann die Plattform zur weiteren Nutzung empfohlen werden.Background: Due to the multitude of therapy options the treatment decision after diagnosis of a localised prostate cancer is challenging. Compared to printed booklets, web based information technology offers more possibilities to tailor information to patients’ individual needs. Objectives: To support the decision making process as well as the communication with patients we developed an online tutorial in a systematic process in the German speaking part of Switzerland and then tested it in a pilot study. The study investigated users’ satisfaction, the coverage of information needs, the preparation for decision making and the subjective quality of the decision. Materials and methods: Based on already existing information material the online tutorial was developed in an iterative process using focus groups with patients and urologists. For the following evaluation in eight clinics a total of 87 patients were invited to access the platform and participate in the study. From these patients 56 used the tutorial and 48 answered both surveys (the first one 4 weeks after the first login and the second one 3 months after treatment decision). The surveys used the Preparation for Decision Making Scale (PDMS), the Decisional Conflict Scale (DCS), and the Decisional Regret Scale (DRS). Results and Conclusion: Satisfaction with the tutorial is very high among patients with newly diagnosed localized prostate cancer. Users find their information needs sufficiently covered. Three months after the decision they felt that they were well prepared for the decision making (Mean PDMS 75, SD 23), they had low decisional conflict (Mean DCS 9.6, SD 11) and almost no decisional regret (Mean DRS 6.4, SD 9.6). Based on these findings the further use of the tutorial can be recommended

    Efficient Finite Groups Arising in the Study of Relative Asphericity

    Get PDF
    We study a class of two-generator two-relator groups, denoted Jn(m, k), that arise in the study of relative asphericity as groups satisfying a transitional curvature condition. Particular instances of these groups occur in the literature as finite groups of intriguing orders. Here we find infinite families of non-elementary virtually free groups and of finite metabelian non-nilpotent groups, for which we determine the orders. All Mersenne primes arise as factors of the orders of the non-metacyclic groups in the class, as do all primes from other conjecturally infinite families of primes. We classify the finite groups up to isomorphism and show that our class overlaps and extends a class of groups Fa,b,c with trivalent Cayley graphs that was introduced by C.M.Campbell, H.S.M.Coxeter, and E.F.Robertson. The theory of cyclically presented groups informs our methods and we extend part of this theory (namely, on connections with polynomial resultants) to ?bicyclically presented groups? that arise naturally in our analysis. As a corollary to our main results we obtain new infinite families of finite metacyclic generalized Fibonacci groups
    corecore