Circuit de commande pour Anti Collision Lamps ACL

Objectif Les ACL sont des ampoules 28V/200W utilisés dans le domaine de l’éclairage professionnel. Habituellement, 8 ampoules sont branchées en série sur le réseau. Suite à ce montage, une commande individuelle de la luminosité n’est pas possible. L’appareil conçu dans ce projet met toutes les ampoules en parallèle sur un bus de tension continue à 28Vdc. La commande individuelle est maintenant possible. Une protection anti-courtcircuit est aussi conçue afin de sécuriser l’installation. Pour alimenter le bus de tension continue, un pont H résonnant est utilisé. Pour diminuer au mieux les pertes de ce système, un redresseur actif est utilisé. Ce dernier fonctionne en utilisant la tension induite d’une self saturable. Résultats L’alimentation du bus de tension continue au travers du redresseur actif n’a pas pu être réalisée car le signal de la self saturable n’est pas assez fiable. La protection anti-court-circuit fonctionne correctement. La lampe fait du bruit lorsque celle est alimentée par des flancs de courant trop brusques à des fréquences audibles. La solution consisterait à l’alimenter à des fréquences élevées.Ziel ACLs sind Lampen 28V/200W, welche im Bereich der professionellen Beleuchtung verwendet werden. Normalerweise sind 8 Lampen in Serie am Netz angeschlossen. Durch diese Anordnung ist eine individuelle Lichtsteuerung nicht möglich. Mit dem in diesem Projekt zu entwickelnden Gerät werden alle Lampen parallel auf einen Spannungsbus von 28Vdc gelegt: Dadurch wird die individuelle Ansteuerung ermöglicht. Zur besseren Sicherheit wird auch eine Kurzschlusssicherheit realisiert. Der Spannungsbus wird mittels einer resonanten H-Brückenschaltung verwirklicht. Resultate Der synchrone Gleichrichter konnte nicht getestet werden da die Steuersignalgenerierung mit Sättigungsdrossel nicht zuverlässig funktioniert. Die Kurzschlusssicherheit funktioniert einwandfrei. Im Betrieb der Lampe entsteht ein störendes Geräusch, weil die Ansteuerung mit steilen Stromflanken sich in hörbaren Frequenzen abspielt. Zur Behebung dieses Geräusches können Speisungen mit höheren Schaltfrequenzen verwendet werden

Peripheral nerve-derived VEGF promotes arterial differentiation via neuropilin 1-mediated positive feedback

In developing limb skin, peripheral nerves are required for arterial differentiation, and guide the pattern of arterial branching. In vitro experiments suggest that nerve-derived VEGF may be important for arteriogenesis, but its role in vivo remains unclear. Using a series of nerve-specific Cre lines, we show that VEGF derived from sensory neurons, motoneurons and/or Schwann cells is required for arteriogenesis in vivo. Arteriogenesis also requires endothelial expression of NRP1, an artery-specific coreceptor for VEGF^(164) that is itself induced by VEGF. Our results provide the first evidence that VEGF is necessary for arteriogenesis from a primitive capillary plexus in vivo, and show that in limb skin the nerve is indeed the principal source of this signal. They also suggest a model in which a `winner-takes-all' competition for VEGF may control arterial differentiation, with the outcome biased by a VEGF^(164)-NRP1 positive-feedback loop. Our results also demonstrate that nerve-vessel alignment is a necessary, but not sufficient, condition for nerve-induced arteriogenesis. Different mechanisms therefore probably underlie these endothelial patterning and differentiation processes

Qualitätsmanagement und Social Media

Basierend auf den technischen Entwicklungen des Internets in den letzten Jahren nimmt die Nutzung sowohl im privaten als auch im geschäftlichen Bereich ständig zu. Durch seine zunehmend bessere Unterstützung der Prozessabläufe in Organisationen steigt die Nachfrage nach Lösungen für verschiedene Querschnittsfunktionen, wie beispielsweise der Dokumentationspflichten im Qualitätsmanagement. Im Rahmen dieses Beitrages wird ein Ansatz aufgezeigt, wie sich moderne Techniken aus dem Bereich des Social Media nutzen lassen, um Qualitätsmanagement-Handbücher zu erstellen und das Leben dieser Inhalte zu intensivieren. Ein besonderes Augenmerk liegt dabei auf der Zusammenarbeit aller Mitarbeiter einer Organisation

Antibiotic Therapy of Infections Due to Pseudomonas aeruginosa in Normal and Granulocytopenic Mice: Comparison of Murine and Human Pharmacokinetics

An effort was made to elucidate the limits of drug-activity tests in small animals. Human plasma kinetics of gentamicin, netilmicin, ticarcillin, ceftazidime, and ceftriaxone were approximated in normal and in granulocytopenic mice infected with various strains of Pseudomonas aeruginosa in the thigh muscle or intraperitoneally. The effect of such dosing on bacterial time-kill curves and on survival was compared with the effect of identical amounts of drug given as a single-bolus injection. With β-lactams, a highly significant superiority of fractionated dosing (simulated human kinetics) over bolus injections (murine plasma kinetics) was demonstrated, whereas with aminoglycosides it was a single-bolus injection that tended to be more active. Thus, when tested in conventional small-animal models, aminoglycoside activity may be overestimated, whereas β-lactam activity may be underestimated in respect to humans. These differences found in vivo most probably reflect the different pharmacodynamics between aminoglycosides and β-lactam drugs (time-kill curves, dose-response curves, and postantibiotic effect) similar to those previously observed in vitr

Using a multi-level tailored design process to develop a customer satisfaction survey for university evaluation

A multi-level procedure is described in order to develop a total quality management survey tool in the field of engineering academia. As a first step a review of available evaluation tools for universities is conducted, resulting in over 150 items used for evaluation purposes. Secondly all dimensions of educational evaluation used in previous research are summarized, resulting in 15 dimensions. In a third step, items are assigned to the dimensions, overlapping items were combined or removed, and item content and dimensions were adjusted to the specific conditions of the target faculty. Fourthly, the resulting twelve dimensions were used in first, investigative interviews in the target population. Results indicate that eleven dimensions sufficiently mapped all aspects of evaluation. After revising the items to improve understanding in a fifth step cognitive pretests were conducted. The final revision resulted in 83 items assigned to eleven dimensions

VEGF-A has a critical, nonredundant role in angiogenic switching and pancreatic β cell carcinogenesis

AbstractIn the RIP1-Tag2 mouse model of pancreatic islet carcinoma, angiogenesis is switched on in a discrete premalignant stage of tumor development, persisting thereafter. Signaling through VEGF receptor tyrosine kinases is a well-established component of angiogenic regulation. We show that five VEGF ligand genes are expressed in normal islets and throughout islet tumorigenesis. To begin dissecting their contributions, we produced an islet β cell specific knockout of VEGF-A, resulting in islets with reduced vascularity but largely normal physiology. In RIP1-Tag2 mice wherein most oncogene-expressing cells had deleted the VEGF-A gene, both angiogenic switching and tumor growth were severely disrupted, as was the neovasculature. Thus, VEGF-A is crucial for angiogenesis in a prototypical model of carcinogenesis, whose loss is not readily compensated

Photothermal excitation of microcantilevers in liquid: effect of the excitation laser position on temperature and vibrational amplitude

Demands to improve the sensitivity and measurement speed of dynamic scanning force microscopy and cantilever sensing applications necessitate the development of smaller cantilever sensors. As a result, methods to directly drive cantilevers, such as photothermal or magnetic excitation, are gaining in importance. Presented is a report on the effect of photothermal excitation of microcantilevers on the increase in steady-state temperature and the dynamics of higher mode vibrations. First, the local temperature increase upon continuous irradiation with laser light at different positions along the cantilever was measured and compared with finite element analysis data. The temperature increase was highest when the heating laser was positioned at the free end of the cantilever. Next, the laser intensity was modulated to drive higher flexural modes to resonance. The dependence of the cantilever dynamics on the excitation laser position was assessed and was in good agreement with the analytical expressions. An optimal position to simultaneously excite all flexural modes of vibration with negligible heating was found at the clamped end of the cantilever. The reports findings are essential for optimisation of the excitation efficiency to minimise the rise in temperature and avoid damaging delicate samples or functionalisation layers

Fast Diagnostics of BRAF Mutations in Biopsies from Malignant Melanoma

According to the American skin cancer foundation, there are more new cases of skin cancer than the combined incidence of cancers of the breast, prostate, lung, and colon each year, and malignant melanoma represents its deadliest form. About 50% of all cases are characterized by a particular mutation BRAFV600E in the BRAF (Rapid Acceleration of Fibrosarcoma gene B) gene. Recently developed highly specific drugs are able to fight BRAFV600E mutated tumors but require diagnostic tools for fast and reliable mutation detection to warrant treatment efficiency. We completed a preliminary clinical trial applying cantilever array sensors to demonstrate identification of a BRAFV600E single-point mutation using total RNA obtained from biopsies of metastatic melanoma of diverse sources (surgical material either frozen or fixated with formalin and embedded in paraffin). The method is faster than the standard Sanger or pyrosequencing methods and comparably sensitive as next-generation sequencing. Processing time from biopsy to diagnosis is below 1 day and does not require PCR amplification, sequencing, and labels

Development of Robust and Standardized Cantilever Sensors Based on Biotin/Neutravidin Coupling for Antibody Detection

A cantilever-based protein biosensor has been developed providing a customizable multilayer platform for the detection of antibodies. It consists of a biotin-terminated PEG layer pre-functionalized on the gold-coated cantilever surface, onto which NeutrAvidin is adsorbed through biotin/NeutrAvidin specific binding. NeutrAvidin is used as a bridge layer between the biotin-coated surface and the biotinylated biomolecules, such as biotinylated bovine serum albumin (biotinylated BSA), forming a multilayer sensor for direct antibody capture. The cantilever biosensor has been successfully applied to the detection of mouse anti-BSA (m-IgG) and sheep anti-BSA(s-IgG) antibodies. As expected, the average differential surface stress signals of about 5.7 +/- 0.8 x 10(-3) N/m are very similar for BSA/m-IgG and BSA/s-IgG binding, i.e., they are independent of the origin of the antibody. A statistic evaluation of 112 response curves confirms that the multilayer protein cantilever biosensor shows high reproducibility. As a control test, a biotinylated maltose binding protein was used for detecting specificity of IgG, the result shows a signal of bBSA layer in response to antibody is 5.8 x 10(-3) N/m compared to bMBP. The pre-functionalized biotin/PEG cantilever surface is found to show a long shelf-life of at least 40 days and retains its responsivity of above 70% of the signal when stored in PBS buffer at 4 degrees C. The protein cantilever biosensor represents a rapid, label-free, sensitive and reliable detection technique for a real-time protein assay