Bioelectricity, gravity and plants.

This brief review summarizes gravity-induced changes in bioelectric parameters and evaluates their contribution to our understanding of the sensing of gravity, and the transduction and transmission of the gravity stimulus in plants. During the last few decades, information has accumulated demonstrating gravity-induced changes in surface potentials, membrane voltages, endogenous electric currents and ion fluxes. These changes point to the plasma membrane as the site of perception and transduction of the gravity signal.

Synthesis and characterization of an Al(69)(3-) cluster with 51 naked Al atoms: analogies and differences to the previously characterized Al(77)(2-) cluster.

A disproportionation process of a metastable AlCl solution with a simultaneous ligand exchange-Cl is substituted by N(SiMe(3))(2)-leads to a [Al(69)[N(SiMe(3))(2)](18)](3-) cluster compound that can be regarded as an intermediate on the way to bulk metal formation. The cluster was characterized by an X-ray crystal structural analysis. Regarding its structure and the packing within the crystal, this metalloid cluster with 4 times more Al atoms than ligands is compared to the [Al(77)N(SiMe(3))(2)](20)](2-) cluster that has been published four years ago.

Signatures of carrier-wave Rabi flopping in GaAs.

For excitation of the model semiconductor GaAs with optical pulses which are both extremely short ( 5 fs) and extremely intense ( approximately 10(12) W cm(-2)), we can meet the condition that the Rabi frequency becomes comparable to the band gap frequency-a highly unusual and previously inaccessible situation. Specifically, in this regime, we observe carrier-wave Rabi flopping, a novel effect of nonlinear optics which has been predicted theoretically and which is related to the failure of the area theorem.

Film cooling from rows of holes--effect of cooling hole shape and row arrangement on adiabatic effectiveness.

In the present study the film cooling performance in terms of the adiabatic film cooling effectiveness on the scaled suction side model of an actual guide vane was investigated. An infrared thermography measurement system was used to determine highly resolved distribution of models surface temperature. Two different film cooling hole configurations were investigated: a single row of fanshaped holes and a double row of cylindrical holes in staggered arrangement.

Effect of Reynolds number, turbulence level and periodic wake flow on heat transfer on low pressure turbine blades.

The development of effective cooling methods is of major importance for the design of new gas turbines blades. The conception of optimal cooling schemes requires a detailed knowledge of the heat transfer processes on the blade's surfaces. The thermal load of turbine blades is predominantly determined by convective heat transfer which is described by the local heat transfer coefficient.

[Artificial intelligence in sleep analysis (ARTISANA)--modelling visual processes in sleep classification].

We describe a novel approach to the problem of automated sleep stage recognition. The ARTISANA algorithm mimics the behaviour of a human expert visually scoring sleep stages (Rechtschaffen and Kales classification). It comprises a number of interacting components that imitate the stepwise approach of the human expert, and artificial intelligence components.

Comparison of tracking techniques for intraoperative presentation of medical data using a see-through head-mounted display.

Tracking of a see-through head-mounted display is a necessary precondition for proper overlay of virtual data and real scenes within the display. In our contribution, the intention and technique for Intraoperative Presentation will be presented. Focus will be the tracking of the display device.

Autocorrelation spectroscopy on single ultrathin layers of CdSe/ZnSe: hints for a non-thermal distribution of excitons in quantum islands.

Autocorrelation spectroscopy on the basis of thousands of individual near-field photoluminescence spectra of single ultrathin CdSe layers at low temperatures exhibits a strong positive correlation peak around 18 meV energy with a width of 5 meV. Using simulations and experiments as a function of temperature and laser intensity, we can exclude interpretations along the lines of biexcitons or phonon sidebands. We attribute this feature to the splitting of ground state and an excited state in individual quantum islands.

A detailed numerical study of the evolution of soot particle size distributions in laminar premixed flames.

In this work, two numerical techniques, viz. the method of moments and a discrete h-p-Galerkin method, have been applied for numerical simulation of soot formation in a laminar premixed acetylene/oxygen/argon flame. From the evolution of the PAH and the soot particle size distributions, new insight into the different processes of soot formation is provided.

Evaluation of an ELISA and immunoblotting for studying the humoral immune response in Anguillicola crassus infected European eel Anguilla anguilla.

The applicability of an enzyme-linked immunosorbent assay (ELISA) for the detection of anguillicolosis in feral eels was examined using a crude antigen preparation from the body wall of adult Anguillicola crassus. The screening consisted of samples from 100 feral European eels Anguilla anguilla. As a reference the actual status of infection was determined by dissection of the eels' swim-bladders.

Interactive simulation of tooth cleaning with an interdental brush.

Proper cleaning of tooth interspaces is significant to sufficient caries prophylaxis. In this article we present a system for the simulation of this cleaning procedure using an interdental brush. Various application areas for the simulation are presented and the purpose of our work is explained.

Leiperia cincinnalis Sambon, 1922 (Pentastomida) from Nile crocodiles Crocodylus niloticus in the Kruger National Park, South Africa, with a description of the male.

A single male and several adult females of the pentastomid Leiperia cincinnalis were recovered from the trachea of five of six Nile crocodiles examined in 1995 and 1998. Infective larvae, pre-adult males and females, as well as mature males, occurred in clusters in the pulmonary artery but infective larvae and pre-adult females were also occasionally taken from the lungs. Irrespective of the developmental stage, the intensity of infection was 3, 6, 48, 72 and 79.

TEM analysis of epitaxial semiconductor layers with high stacking fault densities considering artifacts induced by the cross-section geometry.

Epitaxial semiconductor layers, in particular II-VI compound semiconductors with the component Se deposited on III-V semiconductor substrates like GaAs or InAs, can contain high densities of stacking faults. CdxMg(1-x)Se layers with Cd-concentrations x of 93% and 57% on InAs(0 0 1) substrates were investigated as typical representatives of this class of heterostructures. The defect structure of the layers is dominated by a high density of stacking fault (SF) pairs bound by Shockley partial dislocations with Burgers vectors b = 1/6 <1 1 2> and a stair-rod dislocation with b = 1/6 <1 1 0> at the intersection line of the pairs.

Synthesis, structures and theoretical investigation of.

The silylated derivative of thiophosphoric acid (S)P(SSiMe3)3 is used as a convenient starting compound for the synthesis of multinuclear Cu and Au cluster complexes. (S)P(SSiMe3)3 reacts with CuCI/PPh3 and [AuCClPPh3] to give the following compounds: [Cu4(P2S6)(PPh3)4] (1), [Cu6(P2S6)Cl2-(PPh3)6] (2) and [Au4(P2S6)(PPh3)4](3). According to X-ray structure determination, these compounds contain P2S6(4-) ions, in which S atoms act as ligands for Cu+ and Au+ ions.

Properties of an electron-density map derived from a limited number of experimentally determined triplet phases.

In a previous communication [Weckert et al. (1999). Acta Cryst.

[Signal analysis of the hemodynamics of extracorporeal circulation for the evaluation of patient status].

The present paper describes the intra-operative evaluation of circulation dynamics during open-heart surgery, with the aim of providing the anaesthetist with objective data for assessing patient status during the procedure. For this purpose, the parameters pulse wave velocity and biological impedance were used. With the aid of these parameters it is possible, in the extracorporeal model, to detect different kinds of stenosis, volume losses, vessel dilatation and vessel constriction.

Feasibility study for the measurement of a large set of triplet phases from a small protein.

The feasibility of measuring a set of triplet phases large enough to solve the structure of a small protein has been evaluated. A total of about 850 triplet phases have been measured from the tetragonal form of hen egg-white lysozyme. From these triplet phases, about 750 single phases can be derived.

Thermal stresses in metal-ceramic specimens for the ISO crack initiation test (three-point flexure bond test).

Objectives: At the October 1996 meeting of the ISO/TC106/SC 2/WG 1 working group, a special three-point flexure test for the characterization of the metal-ceramic bond was incorporated in the standard (ISO CD 9693). Due to the fabrication process, like real porcelain-fused-to-metal (PFM) restorations, the specimens contain thermal (eigen-) stresses upon which the load stresses are superimposed in the actual test. This study is devoted to the determination of these residual thermal stresses.

Al Br ⋅12 THF: The First Polyhedral Aluminum Subhalide-A Step on the Path to a New Modification of Aluminum?

The first polyhedral aluminum subhalide Al Br ⋅20 L forms in the disproportionation of aluminum(I) bromide solutions. The cluster is built up from an Al icosahedron with ten exohedrally bound (formally divalent) Al atoms (see structure). Such a homoatomic framework is unknown for molecular compounds.