Brain homeostasis : VEGF receptor 1 and 2 ; two unequal brothers in mind

Vascular endothelial growth factors (VEGFs), initially thought to act specifically on the vascular system, exert trophic effects on neural cells during development and adulthood. Therefore, the VEGF system serves as a promising therapeutic target for brain pathologies, but its simultaneous action on vascular cells paves the way for harmful side effects. To circumvent these deleterious effects, many studies have aimed to clarify whether VEGFs directly affect neural cells or if the effects are mediated secondarily via other cell types, like vascular cells. A great number of reports have shown the expression and function of VEGF receptors (VEGFRs), mainly VEGFR-1 and -2, in neural cells, where VEGFR-2 has been described as the major mediator of VEGF-A signals. This review aims to summarize and compare the divergent roles of VEGFR-1 and -2 during CNS development and homeostasis

Growth And Plumage Development Of Ducklings In Interior Alaska

Thesis (M.S.) University of Alaska Fairbanks, 196

Simulation of a neural network-driven fuzzy controller

A software simulation package was developed to facilitate the analysis of a fuzzy logic tracking system constructed by first training a neural network. The adaptive vector quantization neural network used a competitive learning algorithm to classify control data from a controller in a noisy environment. The neural network memory generated rules for a fuzzy controller by mapping the state of the network into a predetermined fuzzy database. The software is intended to be expanded to allow further analysis of neural dynamics and to compare the performance of the resulting fuzzy controller to conventional controllers

Lorentz shift measurements in heavily irradiated silicon detectors in high magnetic fields

An external magnetic field exerts a Lorentz force on drifting electric charges inside a silicon strip sensor and thus shifts the cluster position of the collected charge. The shift can be related to the Lorentz angle which is typically a few degrees for holes and a few tens of degrees for electrons in a 4 T magnetic field. The Lorentz angle depends upon magnetic field, electric field inside the sensor and temperature. In this study the sensitivity to radiation for fluences up to 10^16 n/cm^2 has been studied. The Lorentz shift has been measured by inducing ionization with 670 nm red or 1070 nm infrared laser beams injected into the back side of the irradiated silicon sensor operated in magnetic fields up to 8 T. For holes the shift as a function of radiation is increasing, while for electrons it is decreasing and even changes sign. The fact that for irradiated sensors the Lorentz shift for electrons is smaller than for holes, in contrast to the observations in non-irradiated sensors, can be qualitatively explained by the structure of the electric field in irradiated sensors.Comment: Accepted publication for RD09 conference in Proceedings of Scienc

Galaxy Clustering Around Nearby Luminous Quasars

We examine the clustering of galaxies around a sample of 20 luminous low redshift (z<0.30) quasars observed with the Wide Field Camera-2 on the Hubble Space Telescope. The HST resolution makes possible galaxy identification brighter than V=23.5 and as close as 2'' to the quasar. We find a significant enhancement of galaxies within a projected separation of < 100 kpc/h of the quasars. If we model the qso/galaxy correlation function as a power law with a slope given by the galaxy/galaxy correlation function, we find that the ratio of the qso/galaxy to galaxy/galaxy correlation functions is $3.8\pm 0.8$. The galaxy counts within r<15 kpc/h of the quasars are too high for the density profile to have an appreciable core radius ( > 100 kpc). Our results reinforce the idea that low redshift quasars are located preferentially in groups of 10-20 galaxies rather than in rich clusters. We see no significant difference in the clustering amplitudes derived from radio-loud and radio-quiet subsamples.Comment: 16 pages, 3 figures (included), 2 tables, Apj in pres

Standardisierung der Kommunikation als Integrationsansatz für das Bauwesen

Eine der wichtigsten Aufgaben und Herausforderungen der Bauinformatik ist gegenwärtig die Realisierung des durchgängigen, fachübergreifenden Datenflusses im Planungsprozeß eines Bauvorhabens. Im Hinblick auf die internationale Wettbewerbsfähigkeit der deutschen Bauwirtschaft ist es unumgänglich, vorhandene Effizienzpotentiale in der Bauplanung auszuschöpfen, welche durch eine qualitative Verbesserung der Planung sowie durch eine Verringerung der Bearbeitungszeit aller beteiligten Fachplanern erreicht werden können. Nach dem gegenwärtigen Stand der Technik werden die Informationsobjekte standardisiert, damit sie durchgängig nutzbar sind. Diese werden in einem allgemeingültigen Format den speziellen Programmen der Fachplaner zur Verfügung gestellt. In dieser Arbeit wird der Ansatz verfolgt, eine Integration durch die Standardisierung der Kommunikation zwischen den Informationsobjekten und ihren Anwendungsprogrammen zu erreichen. Dabei kann auf die Standardisierung der zu übertragenden Objekte verzichtet werden. Ziel der Ausarbeitung ist die Definition von implementationstechnischen Regeln, die alle auszutauschenden Objekte sowie die Anwendungen, die solche Objekte aufnehmen wollen, erfüllen müssen. Die Bearbeitung der Objekte soll in den gewohnten Anwendungen in unveränderter Weise erfolgen

Bacterial Natural Product Drug Discovery for New Antibiotics: Strategies for Tackling the Problem of Antibiotic Resistance by Efficient Bioprospecting

The problem of antibiotic resistance has become a challenge for our public health and society; it has allowed infectious diseases to re-emerge as a risk to human health. New antibiotics that are introduced to the market face the rise of resistant pathogens after a certain period of use. The relatively fast development of resistance against some antibiotics seems to be closely linked to their microbial origin and function in nature. Antibiotics in clinical use are merely products of microorganisms or derivatives of microbial products. The evolution of these antimicrobial compounds has progressed with the evolution of the respective resistance mechanisms in microbes for billions of years. Thus, antimicrobial resistance genes are present within the environment and can be taken up by pathogens through horizontal gene transfer. Natural products from bacteria are an important source of leads for drug development, and microbial natural products have contributed the most antibiotics in current clinical use. Bioprospecting for new antibiotics is a labor-intensive task as obstacles such as redetection of known compounds and low compound yields consume significant resources. The number of bacterial isolates one can theoretically investigate for new secondary metabolites is, on the other hand, immense. Therefore, the available capacity for biodiscovery should be focused on the most promising sources for chemical novelty and bioactivity, employing the appropriate scientific tools. This can be done by first looking into under- or unexplored environments for bacterial isolates and by focusing on the promising candidates to reduce the number of subjects