The tensor polarization of 5Li (32−) in the reaction α + d → α + p + n

At the Hamburger Isochronous Cyclotron the formation of the particle unstable ground state of ${}^5\text{Li(}\text{3}\text{2}{}^{\mathrm{?}}$ has been investigated in the reaction α + d → α + p + n at E_α = 28.3 MeV. The neutrons were detected in two liquid scintillation counters, while a large Si (Li) detector was used to observe the α-particles. In a first analysis, the tensor polarization parameters of the five-nucleon system ⁵Li are determined from the experimental data. The results are in quite good agreement with theoretical predictions of Hackenbroich et al.     

Investigations of reactions involved in electrothermal atomic absorption procedures: Part 9. An atomization system with controlled atmosphere and temperature for the determination of volatile elements in complex matrices

A controlled temperature controlled atmosphere atomization system is described. The sample is placed on a tungsten wire provided with temperature-controlled heating. After thermal pretreatment of the sample the wire is inserted into a hot quartz tube and rapid vaporization is accomplished by separate electrothermal heating. The pyrolysis products formed are mixed with a gas buffer and are passed through two equilibrium zones. The residence time of the analyte in the system is of the order of seconds so that the probability of attaining a state close to equilibrium is high for high temperatures. A third zone is placed perpendicularly to the others and constitutes the atomic absorption measuring cell. The usefulness of the system is illustrated for the determination of lead, bismuth, cadmium and zinc. The system provides unique possibilities in controlling interference effects in complex matrices. Examples are given for lead in concentrated chloride and sulphate solutions. Good agreement between the experimental results and high-temperature equilibrium calculations was obtained for a large variation in the composition of the gas phase.     

A note on asymptotic inference in a class of non-stationary processes

In this note some problems of asymptotic inference in a class of non-stationary stochastic processes are considered. In particular, it is shown that no criterion based on the existence of uniformly most powerful tests over a local neighborhood can be used in this situation.     

3. Biochemische und klinische Analyse

Ohne Zusammenfassung     

Automatic coulometric titration with photometric end-point detection : Part I. A coulometric titrator based on differential photometric detection

A system for automatic coulometric titrations with photometric end-point detection is described. To compensate for errors caused by gas bubbles and turbidity, the beam is split after passing the titration cell. The intensities of the respective light beams are registered by means of two photodiodes operating in the current mode. The currents are converted to voltages and the logarithm of the quotient is taken. The measured absorbance is only slightly dependent on the variation in the intensity of the incident light. A diminution of one absorbance unit causes a relative error of less than 5%. The deviations due to carbon particles (37–75 μm) were less than 0.002 absorbance units per mg of carbon present in 10 ml of solution. The improvement with respect to errors caused by gas bubbles is illustrated. The fundamental advantage of a one-lamp system over a twolamp system is shown.     

Single-optical-element soft-x-ray interferometry with a laser-plasma x-ray source

We report on a compact interferometer for the water-window soft-x-ray range that is suitable for operation with laser-plasma sources. The interferometer consists of a single diffractive optical element that focuses impinging x rays to two focal spots. The light from these two secondary sources forms the interference pattern. The interferometer was operated with a liquid-nitrogen jet laser-plasma source at lambda=2.88 nm. Scalar wave-field propagation was used to simulate the interference pattern, showing good correspondence between theoretical and experimental results. The diffractive optical element can simultaneously be used as an imaging optic, and we demonstrate soft-x-ray microscopy with interferometric contrast enhancement of a phase object.     

Coupled folding-binding versus docking: a lattice model study

Using a simple hydrophobic/polar protein model, we perform a Monte Carlo study of the thermodynamics and kinetics of binding to a target structure for two closely related sequences, one of which has a unique folded state while the other is unstructured. We obtain significant differences in their binding behavior. The stable sequence has rigid docking as its preferred binding mode, while the unstructured chain tends to first attach to the target and then fold. The free-energy profiles associated with these two binding modes are compared.     

Call for papers Special issue on “Quantum interference and cryptographic keys: novel physics and advancing technologies"

The collective phenomena of quantum interference, including wave particle duality and apparent non-locality, have intrigued the physics community for many years. It is only recently that we have begun to turn these somewhat counter intuitive quantum phenomena to good use. A leading force in that direction is quantum cryptography - absolute secure key exchange encoding data on the polarisation or phase of individual photons, or using the quantum correlations between pairs of particles. Technologies are now implemented to bring the various forms of quantum cryptography to commercial application. At the same time the possibility of communications applications has stimulated the study of a variety of novel quantum interference phenomena. Quantum information experiments involving two, three and four photons are planned and a novel Field of continuous variable (many photon) quantum information has emerged. These various aspects of quantum cryptography are considered in the conference “QUICK: Quan- tum interference and cryptographic keys: novel physics and advancing technologies", taking place in Cargese from April 7 to 13, 2001. Following that conference, we invite submission of original papers to a special issue of the European Physical Journal D, on the following topics: - quantum cryptography technologies, - quantum cryptography systems, - free space quantum cryptography and satellites, - pair-photon sources and multiphoton interference, - single photon sources, - continuous variable quantum information, - security aspects, - cryptographic protocols, - entanglement purification in cryptographic schemes, - novel physics and quantum gates for photonic qubits. The submitted articles should be sent to the EPJ D Editorial Office in Orsay. The deadline is July 15, 2001. We look forward to a stimulating special issue.