510 research outputs found

    Neutrino Masses and Conformal Electro-Weak Symmetry Breaking

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    Dimensional transmutation in classically conformal invariant theories may explain the electro-weak scale and the fact that so far nothing but the Standard Model (SM) particles have been observed. We discuss in this paper implications of this type of symmetry breaking for neutrino mass generation.Comment: 23 pages, 4 figures (one new figure), journal versio

    P4-PSFP: P4-Based Per-Stream Filtering and Policing for Time-Sensitive Networking

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    Time-Sensitive Networking (TSN) extends Ethernet to enable real-time communication, including the Credit-Based Shaper (CBS) for prioritized scheduling and the Time-Aware Shaper (TAS) for scheduled traffic. Generally, TSN requires streams to be explicitly admitted before being transmitted. To ensure that admitted traffic conforms with the traffic descriptors indicated for admission control, Per-Stream Filtering and Policing (PSFP) has been defined. For credit-based metering, well-known token bucket policers are applied. However, time-based metering requires time-dependent switch behavior and time synchronization with sub-microsecond precision. While TSN-capable switches support various TSN traffic shaping mechanisms, a full implementation of PSFP is still not available. To bridge this gap, we present a P4-based implementation of PSFP on a 100 Gb/s per port hardware switch. We explain the most interesting aspects of the PSFP implementation whose code is available on GitHub. We demonstrate credit-based and time-based policing and synchronization capabilities to validate the functionality and effectiveness of P4-PSFP. The implementation scales up to 35840 streams depending on the stream identification method. P4-PSFP can be used in practice as long as appropriate TSN switches lack this function. Moreover, its implementation may be helpful for other P4-based hardware implementations that require time synchronization

    A Survey of Scheduling in Time-Sensitive Networking (TSN)

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    TSN is an enhancement of Ethernet which provides various mechanisms for real-time communication. Time-triggered (TT) traffic represents periodic data streams with strict real-time requirements. Amongst others, TSN supports scheduled transmission of TT streams, i.e., the transmission of their packets by edge nodes is coordinated in such a way that none or very little queuing delay occurs in intermediate nodes. TSN supports multiple priority queues per egress port. The TAS uses so-called gates to explicitly allow and block these queues for transmission on a short periodic timescale. The TAS is utilized to protect scheduled traffic from other traffic to minimize its queuing delay. In this work, we consider scheduling in TSN which comprises the computation of periodic transmission instants at edge nodes and the periodic opening and closing of queue gates. In this paper, we first give a brief overview of TSN features and standards. We state the TSN scheduling problem and explain common extensions which also include optimization problems. We review scheduling and optimization methods that have been used in this context. Then, the contribution of currently available research work is surveyed. We extract and compile optimization objectives, solved problem instances, and evaluation results. Research domains are identified, and specific contributions are analyzed. Finally, we discuss potential research directions and open problems.Comment: 34 pages, 19 figures, 9 tables 110 reference

    Engineering of Corynebacterium glutamicum for growth and production of L-ornithine, L-lysine, and lycopene from hexuronic acids

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    Hadiati A, Krahn I, Lindner S, Wendisch VF. Engineering of Corynebacterium glutamicum for growth and production of L-ornithine, L-lysine, and lycopene from hexuronic acids. Bioresources and Bioprocessing. 2014;1(1): 25

    Compensating for low topic interest and long surveys: a field experiment on nonresponse in web surveys

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    Certain survey characteristics proven to affect response rates, such as a survey’s length and topic, are often under limited control of the researcher. Therefore, survey researchers sometimes seek to compensate for such undesired effects on response rates by employing countermeasures such as material or nonmaterial incentives. The scarce evidence on those factors’ effects in web survey contexts is far from being conclusive. This study is aimed at filling this gap by examining the effects of four factors along with selected interactions presumed to affect response rates in web surveys. Requests to complete a web-based, selfadministered survey were sent to 2,152 owners of personal websites. The 2 X 2 X 2 X 2 fully crossed factorial design encompassed the experimental conditions of (a) high versus low topic salience, (b) short versus long survey, (c) lottery incentive versus no incentive, and (d) no feedback and general feedback (study results) versus personal feedback (individual profile of results). As expected, highly salient and shorter surveys yielded considerably higher unit-response rates. Moreover, partial support was found for interaction hypotheses derived from the leverage-salience theory of survey participation. Offering personalized feedback compensated for the negative effects of low topic salience on response rates. Also, the lottery incentive tended to evoke more responses only if the survey was short (versus long), but this interaction effect was only marginally significant. The results stress the usefulness of a multifactorial approach encompassing interaction effects to understand participation differences in web surveys. (auhtor'S abstract

    Working in future. Summary

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    The world of work in industry is changing: globalisation, growing demand for services, new organisational models, emerging technologies (biotechnology, nanotechnology, ambient intelligence) - many factors are driving the process of change. How these drivers will develop and what work structures can be expected in five to ten years is the subject of this study conducted at Fraunhofer ISI. For this purpose, the researchers evaluated future studies and analysed in parallel which changes have already taken hold. According to the study, two critical developments will become even more acute in the future: The low-skilled will find it even more difficult to find work in the future. At the same time, the shortage of skilled workers - especially engineers, natural scientists and economists - will continue to increase as a result of the identified trends. Here, the study recommends, all options for action should be explored to counteract effectively. Further recommendations are aimed at making the range of training and further education in biotechnology and nanotechnology more application-oriented or placing more emphasis on services in training

    Thick Juice-Based Production of Amino Acids and Putrescine by Corynebacterium glutamicum

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    Meiswinkel T, Lindner S, Wendisch VF. Thick Juice-Based Production of Amino Acids and Putrescine by Corynebacterium glutamicum. Journal of Biotechnology & Biomaterials. 2014;4(1): 167.Thick juice (also regarded as syrup) is an intermediate product of sugar processing. It is cheaper than processed sugar and is mainly composed of sucrose. Sucrose is a preferred carbon source of Corynebacterium glutamicum, a workhorse of biotechnology used for million-ton-scale amino acid production. Here, it is shown for C. glutamicum that sugar beet thick juice led to higher growth rates and faster carbon source consumption than pure sucrose. Comparative DNA microarray analysis revealed differential expression of genes for butyrate and citrate catabolism and of NAD and biotin biosynthesis suggesting provision of these compounds by the thick juice. Thick juice was also shown to be superior to sucrose in production of the amino acids L-lysine, L-glutamate and L-arginine as well as of the diamine putrescine since higher volumetric productivities than with pure sucrose could be achieved. Taken together, sugar beet thick juice was shown to be a carbon source for growth and amino acid and diamine production of C. glutamicum superior to pure sucrose
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