Effect of morphine applied by intrapallidal microdialysis on the release of dopamine in the nucleus accumbens

The effect of morphine, administered intrapallidally, on extracellular concentrations of DA, DOPAC, and HVA in the nucleus accumbens and striatum was studied in the behaving rat using the in vivo microdialysis technique. Unilateral application of morphine hydrochloride was performed through microdialysis probes into the rat ventral pallidum (10 microliters of 0, 2.6, 4.0, 13.0, and 26.0 mM) or globus pallidus (10 microliters of 0 and 26.0 mM). The levels of DA, DOPAC, and HVA were measured using the HPLC with EC detection in dialysates collected from the nucleus accumbens, anteromedial, and anterolateral striatum. Samples were taken every 45 min over 3 h before and over 5 h after morphine or vehicle administration. Administration of morphine into the ventral pallidum resulted in increased DOPAC and HVA concentrations in the nucleus accumbens. Pretreatment with naloxone (1 mg/kg, SC) abolished this effect of morphine. Administration of morphine into the globus pallidus resulted in increased DA, DOPAC, and HVA concentrations in the nucleus accumbens and DA in the anteromedial striatum. The levels of DA and metabolites in anterolateral striatum remained rather unchanged following morphine administered into the ventral pallidum or the globus pallidus. The changes in DA neurotransmission into the nucleus accumbens induced by morphine application into the ventral pallidum and globus pallidus are reminiscent of a phasic and tonic release of DA respectively. The results show that intrapallidal morphine increases DA neurotransmission in nucleus accumbens and suggest that the effect of morphine is mediated by ventral pallidum/mesolimbic and globus pallidus/thalamocortical pathways, depending on the site of injection.     

Analysis of thin walled structures using the boundary element method

In this article the direct boundary element formulations of stretching and bending plate problems are combined together to solve thin walled structures and other similar frames. The final system is obtained by assuming each individual plane structural element as a subregion. After the necessary transforms of these equations they can be combined together taking into account the displacement compatibility and equilibrium conditions.     

A comparison of leaf-spring with aircushion trailer suspensions in the transport environment

Packaging engineers need to be able to accurately determine the forces present in the shipping environment in order to protect packaged goods. The purpose of this study was to determine the vertical vibration levels measured in three separate truck-trailer suspension systems; conventional leaf-spring, conventional air-ride and damaged air-ride. The main conclusion reached in this study is that the air-ride suspension when maintained gives lower power density (PD) levels on all road surfaces studied. A damaged air-ride suspension and leaf-spring suspension are very similar in response frequencies, although the damaged air-ride produces higher vibration levels at lower frequencies.     

Entfestigungsverhalten des Stahls 50 CrV4 bei der thermomechanischen Behandlung

Softening behaviour of 50 CrV4 steel on thermomechanical treatment Determination of static softening of austenite on thermomechanical treatment of steel by rolling. Analysed was the development of the austenite structure and influencing the work softening processes depending on the deformation-temperature-time mode. The static softening processes were modelled mathematically by using Avrami's relationships.     

Wigner-space synthesis of discrete-time periodic signals

A procedure that facilitates at least-squares synthesis of periodic, discrete-time signals from Wigner quasi-distributions is proposed. The scheme is based on expanding the desired time sequence on a generally nonorthogonal, Gabor-type basis whose associated biorthogonal function presumably exists. The specific basis selection may crucially affect the efficiency and quality of the ensuing synthesis procedure. The cited basis type constitutes a considerable generalization over the standardly used orthogonal variety, thus creating previously unavailable degrees of freedom. Of primary significance is the acquired capability of generating time-frequency basis functions that are well localized. Localization is a highly desirable property that can advantageously serve in various applications. It is shown and numerically demonstrated that benefits of localization as well as the fact that achieving effective time-frequency basis localization renders a certain degree of oversampling unavoidable     

Comparative study of lipid systems from various sources by rotational viscometry and potentiometry

We carried out the analysis of lecithins with a common polar group and paraffin chains of different lengths and degree of saturation at two levels, namely: (a) that of the paraffin chain proper, by studying whether structural defects arising from the different mobility of the lipid chains affected their rheological properties; and (b) that of the polar group, which is known to be affected by perturbations to the paraffin chain, and so should its ionization.     

The use of probability theory in fracture mechanics—A case study

A probabilistic approach to fracture mechanics in the form of a typical case study is described wherein the integrity of a high-pressure water pipeline is assessed. An analysis methodology is discussed incorporating the probability density functions of defect sizes, the statistics of defect occurrences and the statistical distribution of material properties. This method enables the analyst to supply a very simple assessment of safety, based on the probability of failure (a single number) which may be compared to accepted industrial standards (e.g. 10⁻⁶ for nuclear applications). It is argued that this method often offers the only way to scientifically and economically assess the integrity of fracture prone structures.     

Relative permeability measurements for two phase flow in unconsolidated sands

This paper presents the results of laboratory measurements of relative permeability for two phase flow in partially saturated samples of unconsolidated sands. Relative permeabilities for tap water and air, de-aired water and nitrogen were measured using a steady—state technique. Three different sand samples (fine sand, heterogeneous sand and coarse sand) were tested.