Evaluation of a low-cost 3D sound system for immersive virtual reality training systems

Since head mounted displays (HMD), datagloves, tracking systems, and powerful computer graphics resources are nowadays in an affordable price range, the usage of PC-based "virtual training systems" becomes very attractive. However, due to the limited field of view of HMD devices, additional modalities have to be provided to benefit from 3D environments. A 3D sound simulation can improve the capabilities of VR systems dramatically. Unfortunately, realistic 3D sound simulations are expensive and demand a tremendous amount of computational power to calculate reverberation, occlusion, and obstruction effects. To use 3D sound in a PC-based training system as a way to direct and guide trainees to observe specific events in 3D space, a cheaper alternative has to be provided, so that a broader range of applications can take advantage of this modality. To address this issue, we focus in this paper on the evaluation of a low-cost 3D sound simulation that is capable of providing traceable 3D sound events. We describe our experimental system setup using conventional stereo headsets in combination with a tracked HMD device and present our results with regard to precision, speed, and used signal types for localizing simulated sound events in a virtual training environment     

Platelet-Released Growth Factors Influence Wound Healing-Associated Genes in Human Keratinocytes and Ex Vivo Skin Explants

Platelet-released growth factors (PRGFs) or other thrombocyte concentrate products, e.g., Platelet-Rich Fibrin (PRF), have become efficient tools of regenerative medicine in many medical disciplines. In the context of wound healing, it has been demonstrated that treatment of chronic or complicated wounds with PRGF or PRF improves wound healing in the majority of treated patients. Nevertheless, the underlying cellular and molecular mechanism are still poorly understood. Therefore, we aimed to analyze if PRGF-treatment of human keratinocytes caused the induction of genes encoding paracrine factors associated with successful wound healing. The investigated genes were Semaphorin 7A (SEMA7A), Angiopoietin-like 4 (ANGPLT4), Fibroblast Growth Factor-2 (FGF-2), Interleukin-32 (IL-32), the CC-chemokine-ligand 20 (CCL20), the matrix-metalloproteinase-2 (MMP-2), the chemokine C-X-C motif chemokine ligand 10 (CXCL10) and the subunit B of the Platelet-Derived Growth Factor (PDGFB). We observed a significant gene induction of SEMA7A, ANGPLT4, FGF-2, IL-32, MMP-2 and PDGFB in human keratinocytes after PRGF treatment. The CCL20- and CXCL10 gene expressions were significantly inhibited by PRGF therapy. Signal transduction analyses revealed that the PRGF-mediated gene induction of SEMA7A, ANGPLT4, IL-32 and MMP-2 in human keratinocytes was transduced via the IL-6 receptor pathway. In contrast, EGF receptor signaling was not involved in the PRGF-mediated gene expression of analyzed genes in human keratinocytes. Additionally, treatment of ex vivo skin explants with PRGF confirmed a significant gene induction of SEMA7A, ANGPLT4, MMP-2 and PDGFB. Taken together, these results describe a new mechanism that could be responsible for the beneficial wound healing properties of PRGF or related thrombocytes concentrate products such as PRF.     

全球BCF地毯丝产能扩大

过去几年里,BCF丝及设备的市场都在积极地发展.尽管2003年全球BCF地毯丝的产量还在210万t左右,但是2006年产量有望达到228万t,年增长率接近4%.     

Zur Bestimmung der Wärmeleitfähigkeit von Eisenschwamm

Messung der Wärmeleitfähigkeit von Eisenschwamm nach der Laserimpuls-Methode bei Temperaturen zwischen 20 und 1400°C. Vergleich der Meßwerte mit der Wärmeleitfähigkeit von Reineisen. Theoretische Überlegungen zum Temperaturverlauf der Wärmeleitfähigkeit des Eisenschwamms.     

High pressure thermal denaturation kinetics of whey proteins

Pressure processing of foodstuff has been applied to produce or modify proteinaceous gel structures. In real pressure processing the treatment is non-isothermal, due to the adiabatic nature of the process and the heat loss from the product to the vessel. In order to estimate the effect of pressurization on milk constituents pressure and temperature dependent kinetics were determined separately from each other. In a detailed kinetic study whey protein isolate was treated under isobaric (200 to 800 MPa) and isothermal conditions (-2 to 70 degrees C), and the resulting degree of denaturation of beta-lactoglobulin A and B and alpha-lactalbumin was analysed. Kinetic parameters of denaturation were estimated using a one step non-linear regression method which allowed a global fit of the whole data set. The isobaric isothermal denaturation of beta-lactoglobulin and alpha-lactalbumin was found to follow third and second order kinetics, respectively. Isothermal pressure denaturation of both beta-lactoglobulin fractions do not differ significantly and were characterized by an activation volume decreasing with increasing temperature from -10 to about -30 ml mol(-1), which demonstrates that the denaturation rate is accelerated with increasing temperature. The activation energy of about 70 to 100 kJ mol(-1) obtained for beta-lactoglobulin A and B is not dependent to a great extent on the pressure which indicates that above 200 MPa denaturation rate is limited by the aggregation rate while pressure forces unfolding of the molecule.     

Are inclined screw blades for vertical grain augers advantageous?

Due to modern technology, screw blades are often manufactured by rolling them out of one single strip of steel. When simultaneously some blade inclination is applied, less residual stresses and/or larger possible ratios between outer and shaft diameter are claimed by some manufacturers, which seems plausible. However, it is sometimes also claimed that the efficiency of the conveyors is increased by such an inclined blade. The underlying idea is that the blade will cause extra pressure between the material to be conveyed and the tube of the conveyor. This in turn would delay the angular speed of the material, thus resulting in a steeper upward motion.In order to investigate this phenomenon, previous investigations based upon the conveyance of a single point mass have been modified for an inclined screw blade. It appeared that such a blade has no significant advantages over a normal one, which was confirmed by a series of tests. For completeness, tests were also carried out with a leading screw, resulting in worse results.In the case that the pitch equals the diameter and for friction coefficients of 0.3 at both screw blade and tube wall, an increase of no more than 5% in capacity will occur, even for blade inclination angles up to 30°. At the same time, however, the efficiency can drop by 15%.     

Contents of heavy metals in tree components of economical important species in relation to their residual utilisation

Zusammenfassung An 7 forstlich genutzten Standortsgruppen mit Kiefern- Fichten-, Eichen- oder Buchenbestockung wurden die Schwermetallgehalte ermittelt. Die Gehalte unterschieden sich je nach Baumart, Baumkompartiment und Standort z.T. erheblich. Bei den Schwermetallen hing die Höhe der Gehalte weniger von der Baumart ab, hier hatte die Belastungssituation des Standortes den stärksten Effekt auf die Elementgehalte. So wiesen beispielsweise nahezu alle Biomassesortimente aus Bergwerks- oder Hüttenregionen deutlich erhöhte Schwermetallgehalte auf, die die Grenzwerte zahlreicher Verordnungen übertreten und die Verwertung verschiedener Biomassesortimente für einzelne Nutzungen einschränken oder verhindern können. Dagegen können die Schwermetallgehalte von Biomassesortimenten gering belasteter Standorte i.d.R. als unbedenklich gelten

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Contents of heavy metals in tree components of economical important species in relation to their residual utilisation

At seven forest site classes with pine, spruce, oak or beech stands the heavy metal contents of the trees were determined. The element contents differed substantially among tree species, tree compartments and forest sites. The amount of heavy metal content depended very little on tree species but mostly on the degree of pollutant inputs. For example, all tree components had high levels of heavy metals when grown on mine sits (open pits) and on close to ore treated areas. Biomass from some of these areas may exceed the limit of allowed values by several folds and thereby may not be allowed to be used for specific purposes. Heavy metal contents of biomass components from unpolluted areas may be low providing no constrain to their use.