2,858 research outputs found
On variable hydrostatic transmission for road vehicles, powered by supply of fluid at constant pressure
Various hydrostatic power transmission systems for automotive applications with power supply at constant pressure and unrestricted flow and with a Volvo Flygmotor variable displacement motor as the principal unit were investigated. Two most promising concepts were analyzed in detail and their main components optimized for minimum power loss at the EPA Urban Driving Cycle. The best fuel consumption is less than 10 lit. per 100 kM for a 1542 kG vehicle with a hydrostatic motor and a two speed gear box in series (braking power not recovered). Realistic system pressure affects the fuel consumption just slightly, but the package volume/weight drastically. Back pressure increases losses significantly. Special attention was paid to description of the behavior and modeling of the losses of variable displacement hydrostatic machines
Inhibition by alloxan of mitochondrial aconitase and other enzymes associated with the citric acid cycle
AbstractConsiderable variations were found in the in vitro effect of alloxan on mouse liver enzymes associated with the citric acid cycle. The following approximative alloxan concentrations induced 50% inhibition of enzyme activity: 10−6 M for aconitase, 10−4 M for NAD-linked isocitrate dehydrogenase, glutamate dehydrogenase, α-ketoglutarate dehydrogenase, succinyl-CoA synthetase and fumarase, and 10−3 M for citrate synthase and NADP-linked isocitrate dehydrogenase. Pyruvate dehydrogenase, succinate dehydrogenase and malate dehydrogenase were not inhibited by 10−3 M alloxan. The inhibition of aconitase was competitive both when using mouse liver and purified porcine heart enzyme. The Ki values for the purified enzyme in the presence of 5 μM alloxan were 0.22 μM with citrate, 4.0 μM with cis-aconitate and 0.62 μM with isocitrate as substrate. The high sensitivity of aconitase for inhibition by alloxan probably plays a prominent role for the toxic effects of alloxan
Expertise Shapes Multimodal Imagery for Wine
Although taste and smell seem hard to imagine, some people nevertheless report vivid imagery in these sensory modalities. We investigate whether experts are better able to imagine smells and tastes because they have learned the ability, or whether they are better imaginers in the first place, and so become experts. To test this, we first compared a group of wine experts to yoked novices using a battery of questionnaires. We show for the first time that experts report greater vividness of wine imagery, with no difference in vividness across sensory modalities. In contrast, novices had more vivid color imagery than taste or odor imagery for wines. Experts and novices did not differ on other vividness of imagery measures, suggesting a domain-specific effect of expertise. Critically, in a second study, we followed a group of students commencing a wine course and a group of matched control participants. Students and controls did not differ before the course, but after the wine course students reported more vivid wine imagery. We provide evidence that expertise improves imagery, exemplifying the extent of plasticity of cognition underlying the chemical senses
Mutually unbiased bases: tomography of spin states and star-product scheme
Mutually unbiased bases (MUBs) are considered within the framework of a
generic star-product scheme. We rederive that a full set of MUBs is adequate
for a spin tomography, i.e. knowledge of all probabilities to find a system in
each MUB-state is enough for a state reconstruction. Extending the ideas of the
tomographic-probability representation and the star-product scheme to
MUB-tomography, dequantizer and quantizer operators for MUB-symbols of spin
states and operators are introduced, ordinary and dual star-product kernels are
found. Since MUB-projectors are to obey specific rules of the star-product
scheme, we reveal the Lie algebraic structure of MUB-projectors and derive new
relations on triple- and four-products of MUB-projectors. Example of qubits is
considered in detail. MUB-tomography by means of Stern-Gerlach apparatus is
discussed.Comment: 11 pages, 1 table, partially presented at the 17th Central European
Workshop on Quantum Optics (CEWQO'2010), June 6-11, 2010, St. Andrews,
Scotland, U
Modification and cross-linking parameters in hyaluronic acid hydrogels—Definitions and analytical methods
AbstractDefinitions and methods for the quantification of degree of modification and cross-linking in cross-linked hyaluronic acid (HA) hydrogels are outlined. A novel method is presented in which the HA hydrogel is degraded by the enzyme chondroitinase AC and the digest product analyzed by size exclusion chromatography combined with electrospray ionization mass spectrometry (SEC–ESI-MS). This method allows for the determination of effective cross-linker ratio (CrR) which together with the degree of modification (MoD), determined by, e.g. 1H NMR spectroscopy, enables the calculation of the degree of substitution (DS) and degree of cross-linking (CrD).The method, could be applicable to the major cross-linked HA hydrogels currently on the market, and is exemplified here by application to two HA hydrogels. The definitions and methods presented are important contributions in attempts to find relationships between MoD, DS and CrD to mechanical properties as well as to biocompatibility of HA hydrogels
Expertise in crime scene examination: comparing search strategies of expert and novice crime scene examiners in simulated crime scenes.
Zebularine induces long-term survival of pancreatic islet allotransplants in streptozotocin treated diabetic rats.
Coping with the immune rejection of allotransplants or autologous cells in patients with an active sensitization towards their autoantigens and autoimmunity presently necessitates life-long immune suppressive therapy acting on the immune system as a whole, which makes the patients vulnerable to infections and increases their risk of developing cancer. New technologies to induce antigen selective long-lasting immunosuppression or immune tolerance are therefore much needed
Vibrotactile pedals : provision of haptic feedback to support economical driving
The use of haptic feedback is currently an underused modality in the driving environment, especially with respect to vehicle manufacturers. This exploratory study evaluates the effects of a vibrotactile (or haptic) accelerator pedal on car driving performance and perceived workload using a driving simulator. A stimulus was triggered when the driver exceeded a 50% throttle threshold, past which is deemed excessive for economical driving. Results showed significant decreases in mean acceleration values, and maximum and excess throttle use when the haptic pedal was active as compared to a baseline condition. As well as the positive changes to driver behaviour, subjective workload decreased when driving with the haptic pedal as compared to when drivers were simply asked to drive economically. The literature suggests that the haptic processing channel offers a largely untapped resource in the driving environment, and could provide information without overloading the other attentional resource pools used in driving
Imaginary Phases in Two-Level Model with Spontaneous Decay
We study a two-level model coupled to the electromagnetic vacuum and to an
external classic electric field with fixed frequency. The amplitude of the
external electric field is supposed to vary very slow in time. Garrison and
Wright [{\it Phys. Lett.} {\bf A128} (1988) 177] used the non-hermitian
Hamiltonian approach to study the adiabatic limit of this model and obtained
that the probability of this two-level system to be in its upper level has an
imaginary geometric phase. Using the master equation for describing the time
evolution of the two-level system we obtain that the imaginary phase due to
dissipative effects is time dependent, in opposition to Garrison and Wright
result. The present results show that the non-hermitian hamiltonian method
should not be used to discuss the nature of the imaginary phases in open
systems.Comment: 11 pages, new version, to appear in J. Phys.
- …