1,999 research outputs found

    Concept for an event-triggered wireless sensor network for vibration-based diagnosis in trams

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    Trams are the most durable and resource efficient forms of public transportation. However, because of the varying wear in dependence on their operation mode and load levels, there is a need for condition monitoring and early maintenance. Vibration sensors provide interesting possibilities to monitor the relevant tram drive components. In this contribution we investigate their use under real conditions. On the basis of cable bound vibration measurements, the influence of the crossed track section, the tram speed and the tram condition is shown. Based on the investigation results, a concept is proposed in which a meshed and wireless sensor network, event-triggered, can acquire vibration measurement data, which are suitable for the diagnosis of tram drive components. The proposed concept has the potential to operate the sensor nodes in an energy efficient way through decentralized data evaluation taking place on the sensor node

    Neonatological and pulmonological management of bilateral pulmonary sequestration in a neonate

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    Background: Bronchopulmonary sequestration is a lung malformation characterized by nonfunctioning lung tissue without primary communication with the tracheobronchial tree. Intrauterine complications such as mediastinal shift, pleural effusion or fetal hydrothorax can be present. We present the case of a newborn with bilateral intralobar pulmonary sequestration. Methods: Prenatal ultrasonography in a primigravida at 20 weeks of gestation revealed echogenic masses in the right fetal hemithorax with mediastinal shift towards the left side. Serial ultrasound confirmed persistence of the lesion with otherwise appropriate fetal development. Delivery was uneventful and physical examination revealed an isolated intermittent tachypnea. Chest CT scan and CT angiography showed a bilateral intrathoracic lesion with arterial supply from the aorta. Baby lung function testing suggested possible multiple functional compartments. Results: Right and left thoracotomy was performed at the age of 7 months. A bilateral intralobar sequestration with vascularisation from the aorta was resected. Pathological and histological examination of the resected tissue confirmed the surgical diagnosis. At the age of 24 months, the child was doing well without pulmonary complications. Conclusions: Bilateral pulmonary sequestration requires intensive prenatal and postnatal surveillance. Though given the fact of a bilateral pulmonary sequestration, postnatal outcome showed similar favourable characteristics to an unilateral presentation. Baby lung function testing could provide additional information for optimal postnatal management and timing of surgical interventio

    Grundlagen der Suchtechnologie

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    Nach einem kurzen historischen Abriss (vom ersten Register, über die ersten Idee einer Suchmaschine bis zu Google) wird die Vorgehensweise bei der automatischen Indexierung von Dokumenten vorgestellt. Wie gelangt ein Dokument in den Index und wie und welcher Reihenfolge (Ranking) wird es wieder ausgegeben. Anschließend werden die verschiedenen Suchtechnologie-Arten (Zeichenabgleichung, Reguläre Ausdrücke, Fuzzy-Suche, Phonetische Suche, Semantische Suche) und Ranking-Verfahren (Formale Sortierung, On-Page-Faktoren, On-Site-Faktoren, Link-Faktoren, Eigenschaften und Verhalten der Nutzer) vorgestellt. Zum Abschluss wird ein kurzer Ausblick auf Suchmaschinenoptimierung gegeben

    Concurrently Secure Blind Schnorr Signatures

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    Many applications of blind signatures (notably in blockchains) require the resulting signatures to be compatible with the existing system. This makes schemes that produce Schnorr signatures (now being standardized and supported by major cryptocurrencies like Bitcoin) desirable. Unfortunately, the existing blind-signing protocol has been shown insecure when users can open signing sessions concurrently (Eurocrypt\u2721). On the other hand, only allowing sequential sessions opens the door to denial-of-service attacks. We present the first practical, concurrently secure blind-signing protocol for Schnorr signatures, using the standard primitives NIZK and PKE and assuming that Schnorr signatures themselves are unforgeable. We cast our scheme as a generalization of blind and partially blind signatures: we introduce the notion of predicate blind signatures, in which the signer can define a predicate that the blindly signed message must satisfy. We provide proof-of-concept implementations and benchmarks for various choices of primitives and scenarios, including blindly signing Bitcoin transactions conditioned on certain properties

    Grundlagen der Suchtechnologie

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    Nach einem kurzen historischen Abriss (vom ersten Register, über die ersten Idee einer Suchmaschine bis zu Google) wird die Vorgehensweise bei der automatischen Indexierung von Dokumenten vorgestellt. Wie gelangt ein Dokument in den Index und wie und welcher Reihenfolge (Ranking) wird es wieder ausgegeben. Anschließend werden die verschiedenen Suchtechnologie-Arten (Zeichenabgleichung, Reguläre Ausdrücke, Fuzzy-Suche, Phonetische Suche, Semantische Suche) und Ranking-Verfahren (Formale Sortierung, On-Page-Faktoren, On-Site-Faktoren, Link-Faktoren, Eigenschaften und Verhalten der Nutzer) vorgestellt. Zum Abschluss wird ein kurzer Ausblick auf Suchmaschinenoptimierung gegeben

    Highly Sensitive Detection of the Antibiotic Ciprofloxacin by Means of Fiber Enhanced Raman Spectroscopy

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    Sepsis and septic shock exhibit a rapid course and a high fatality rate. Antibiotic treatment is time-critical and precise knowledge of the antibiotic concentration during the patients’ treatment would allow individual dose adaption. Over- and underdosing will increase the antimicrobial efficacy and reduce toxicity. We demonstrated that fiber enhanced Raman spectroscopy (FERS) can be used to detect very low concentrations of ciprofloxacin in clinically relevant doses, down to 1.5 µM. Fiber enhancement was achieved in bandgap shifted photonic crystal fibers. The high linearity between the Raman signals and the drug concentrations allows a robust calibration for drug quantification. The needed sample volume was very low (0.58 µL) and an acquisition time of 30 s allowed the rapid monitoring of ciprofloxacin levels in a less invasive way than conventional techniques. These results demonstrate that FERS has a high potential for clinical in-situ monitoring of ciprofloxacin levels

    Comparison of the Effects of Early Pregnancy with Human Interferon, Alpha 2 (IFNA2), on Gene Expression in Bovine Endometrium

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    Interferon tau (IFNT), a type I IFN similar to alpha IFNs (IFNA), is the pregnancy recognition signal produced by the ruminant conceptus. To elucidate specific effects of bovine IFNT and of other conceptus-derived factors, endometrial gene expression changes during early pregnancy were compared to gene expression changes after intrauterine application of human IFNA2. In experiment 1, endometrial tissue samples were obtained on Day (D) 12, D15, and D18 postmating from nonpregnant or pregnant heifers. In experiment 2, heifers were treated from D14 to D16 of the estrous cycle with an intrauterine device releasing IFNA2 or, as controls, placebo lipid extrudates or PBS only. Endometrial biopsies were performed after flushing the uterus. All samples from both experiments were analyzed with an Affymetrix Bovine Genome Array. Experiment 1 revealed differential gene expression between pregnant and nonpregnant endometria on D15 and D18. In experiment 2, IFNA2 treatment resulted in differential gene expression in the bovine endometrium. Comparison of the data sets from both studies identified genes that were differentially expressed in response to IFNA2 but not in response to pregnancy on D15 or D18. In addition, genes were found that were differentially expressed during pregnancy but not after IFNA2 treatment. In experiment 3, spatiotemporal alterations in expression of selected genes were determined in uteri from nonpregnant and early pregnant heifers using in situ hybridization. The overall findings of this study suggest differential effects of bovine IFNT compared to human IFNA2 and that some pregnancy-specific changes in the endometrium are elicited by conceptus-derived factors other than IFNT

    Current Redistribution in a Superconducting Multi-Strand 35 kA DC Cable Demonstrator

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    High temperature superconductors (HTS) are discussed as energy-efficient solutions for industrial high-current applications beyond 10 kA e.g., bus bar systems in industrial electrolysis plants. In this contribution, the experimental test of a 3.6-meter-long 35 kA DC demonstrator, made from twelve high-current HTS CrossConductor (HTS CroCo) strands in an liquid nitrogen bath at T = 77 K is presented. In this work, a common connector concept of the twelve HTS CroCo strands is proposed. Compared to earlier results without common connector, lead resistances were effectively reduced and current distribution among the individual strands was significantly facilitated. This is confirmed by the observation of increased critical cable current of 37.6 kA compared to 33 kA in previous work without low-resistive common connector. Additionally, the current range, in which all twelve strands reached their critical electric field, was found to be reduced from >7 kA to 2 kA. Results are discussed and assessed with the help of an electric circuit model, from which the solder resistances at the connections could be obtained by fitting. Particular focus was given to the investigation of current redistribution in the demonstrator. Therefore, a heater was installed on one HTS CroCo strand, and activated to raise the temperature on this strand and quench a single strand locally. It is observed that current is redistributed through the common connectors to the other strands
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