A long-lived magma ocean on a young Moon

A giant impact onto Earth led to the formation of the Moon, resulted in a lunar magma ocean (LMO), and initiated the last event of core segregation on Earth. However, the timing and temporal link of these events remain uncertain. Here, we demonstrate that the low thermal conductivity of the lunar crust combined with heat extraction by partial melting of deep cumulates undergoing convection results in an LMO solidification time scale of 150 to 200 million years. Combining this result with a crystallization model of the LMO and with the ages and isotopic compositions of lunar samples indicates that the Moon formed 4.425 ± 0.025 billion years ago. This age is in remarkable agreement with the U-Pb age of Earth, demonstrating that the U-Pb age dates the final segregation of Earth's core.

PLANET TOPERS: Planets, Tracing the Transfer, Origin, Preservation, and Evolution of their ReservoirS

The Interuniversity Attraction Pole (IAP) 'PLANET TOPERS' (Planets: Tracing the Transfer, Origin, Preservation, and Evolution of their Reservoirs) addresses the fundamental understanding of the thermal and compositional evolution of the different reservoirs of planetary bodies (core, mantle, crust, atmosphere, hydrosphere, cryosphere, and space) considering interactions and feedback mechanisms. Here we present the first results after 2 years of project work.

Mars environment and magnetic orbiter scientific and measurement objectives

In this paper, we summarize our present understanding of Mars' atmosphere, magnetic field, and surface and address past evolution of these features. Key scientific questions concerning Mars' surface, atmosphere, and magnetic field, along with the planet's interaction with solar wind, are discussed. We also define what key parameters and measurements should be performed and the main characteristics of a martian mission that would help to provide answers to these questions. Such a mission--Mars Environment and Magnetic Orbiter (MEMO)--was proposed as an answer to the Cosmic Vision Call of Opportunity as an M-class mission (corresponding to a total European Space Agency cost of less than 300 Meuro). MEMO was designed to study the strong interconnection between the planetary interior, atmosphere, and solar conditions, which is essential to our understanding of planetary evolution, the appearance of life, and its sustainability. The MEMO main platform combined remote sensing and in situ measurements of the atmosphere and the magnetic field during regular incursions into the martian upper atmosphere. The micro-satellite was designed to perform simultaneous in situ solar wind measurements. MEMO was defined to conduct: * Four-dimensional mapping of the martian atmosphere from the surface up to 120 km by measuring wind, temperature, water, and composition, all of which would provide a complete view of the martian climate and photochemical system; Mapping of the low-altitude magnetic field with unprecedented geographical, altitude, local time, and seasonal resolutions; A characterization of the simultaneous responses of the atmosphere, magnetic field, and near-Mars space to solar variability by means of in situ atmospheric and solar wind measurements.

International studies to compare methods for personal sampling of bitumen fumes

A newly recommended Institute of Occupational Medicine (IOM) sampler, optimized for the inhalable fraction, was compared with 'total particulate' samplers currently used by five laboratories in different countries for the analysis of bitumen fumes. Using a laboratory fume generator, all samplers were uniformly exposed to bitumen fumes from typical USA bitumen (commercial Pen 65). The results show that, for laboratory-generated bitumen fumes, benzene-extractable inhalable particulate data for the IOM sampler are consistent with benzene soluble matter data from the other samplers. Direct comparison of the IOM sampler with the 37 mm closed-face cassette (USA sampler) using an identical protocol in a single laboratory gave a ratio of 1.05:1 (USA:IOM). Similarly, for total particulate matter, the standard previously recommended by the American Conference of Governmental Industrial Hygienists (ACGIH), an average value of approximately 1 between the IOM and the five samplers was obtained. For unadulterated bitumen fumes, the geometry of the cassettes does not appear to affect entry of the particles into the sampler. Field studies may show differences in results as other factors, e.g. wind and its effect on sampling efficiency, and also particulates originating from sources other than bitumen, such as dust, are involved. These will require thorough investigation prior to the assessment of the impact of the new sampler and prior to any reconsideration of occupational exposure limits taking into account practical feasibility. Other tests were conducted on the bitumen fume samples including total organic matter, simulated distillation and polycyclic aromatic compound analysis. These additional tests were performed on the fume collected on the filter plus the volatile portion that passed through the filter and was captured on various adsorbent materials. Protocols for sample collection and analysis varied in different countries with results reflective of these differences, suggesting the need for standardization.

X-ray determination of dislocation density and arrangement in plastically deformed copper

Using the kinematical theory of X-ray scattering by crystals with dislocations as developed by Krivoglazet al.and Wilkens, the dislocation content of compressed copper single and polycrystals was investigated by means of profile analysis of selected diffraction peaks. Measurements of radial intensity distributionsI(2θ) were performed with a double-crystal spectrometer in the case of the single crystals and with conventional polycrystal diffractometers in the case of the polycrystals. Additionally, the misorientations Θ occurring within the dislocation cell structure because of the accumulation of excess dislocations of one sign were investigated by means of rocking curves of the single-crystal reflections and by evaluation of electron backscattering patterns (EBSPs). Within a wide deformation range, the mean total dislocation density ρdcan be related well to the flow stressviathe Taylor relationship. Assuming a random distribution of the misorientations Θ between adjacent dislocation cells, the evaluation of the rocking curves gives mean values 〈|Θ|〉 much smaller than those determined by EBSP analysis. For this reason, a model of a dislocation cell structure with restrictedly correlated misorientations, which leads to better agreement of the X-ray and the EBSP data, is proposed.

Motion VEPs with simultaneous measurement of perceived velocity

The dependency of the N200 amplitude of the motion-onset VEP evoked by a parafoveal grating of variable speed (0.25-13.5 deg/s, corresponding to 0.5-27 Hz) and constant contrast (4%) was studied. Additional measurements were made with parafoveally presented gratings of constant speed (2 deg/s, corresponding to 4 Hz) and a variable contrast (0.5-64%) before and after adaptation to a stationary or drifting grating. In this latter experiment, simultaneous psychophysical measurements were made of the perceived speed. The amplitude of the N200 wave increased with increasing stimulus speed within the slow speed range up to 1.5 deg/s (corresponding to 3 Hz). Adaptation to a stationary grating had no significant effect on the relationship between the N200 amplitude and stimulus contrast. Contrary to this, adaptation to a slowly drifting grating (1 deg/s, corresponding to 2 Hz) or to a rapidly drifting grating (4 deg/s, corresponding to 8 Hz) reduced the N200 amplitude significantly. Adaptation to a stationary grating slightly reduced the perceived speed of subsequently viewed gratings. Adaptation to a slowly drifting grating increased the perceived speed of the subsequently viewed gratings, whereas adaptation to a rapidly drifting grating decreased the perceived speed. The findings can be best explained by a two-channel model of speed perception. While the motion VEP reflects the sum of both channel activities, the psychophysical measures point to the antagonistic encoding of low and high velocities.

Similarities and dissimilarities between pattern VEPs and motion VEPs

The contrast response functions (CRF) of pattern-appearance and motion-onset VEPs for periodic stimuli (gratings) were compared. The CRF for pattern-appearance is accelerative for the P100 component and compressive for the N200 component. Contrary to these results, the CRF for motion-onset shows an almost negligible slope for both components within the contrast range tested (0.5-64%). To better isolate the neural contributions to these different VEP components, we studied the effects of prior adaptation to stationary and moving gratings. Adaptation to stationary gratings has no effect on both VEP components for motion-onset and the P100 component for pattern-appearance, but did reduce the amplitude of the N200 for pattern-appearance. Adaptation to slow (1 deg/s) and fast (4 deg/s) gratings left the P100 amplitudes unaltered, while it significantly reduced the N200 amplitudes for both pattern-appearance and motion-onset. These results suggest that the N200 component of the motion-onset VEP is generated by motion-dependent neurons, whereas the same component for pattern-appearance arises from contrast-dependent neurons. The observed differences between P100 and N200 components appear to reflect the activity of both transient and sustained neural mechanisms.

Measurement of vapour-aerosol mixtures

A particular problem in connection with the measurement of hazardous substances is posed by substances or groups of substances which may occur simultaneously in vapour and aerosol form. It is possible that, during sampling, the distribution of the two phases on the sampling medium is subject to changes due to vaporisation of aerosol or condensation of vapour. For workplace assessment purposes, it makes sense to consider the sum of vapour and aerosol, which never changes. Only then can the results of different sampling systems be compared. There are several ways in which vapour-aerosol mixtures can be sampled. Combining adsorption tubes or denuders with filters is the most important. Twofold requirements must be considered in the development of such sampling.

METHODS

Those applying to sampling systems for aerosols as well as those for vapour sampling systems. To satisfy the requirements resulting from these substances and groups of substances, BIA's personal sampling system (PGP) was extended. In addition to the sampling head for inhalable dust (GSP), originally designed for a flow rate of 3.5 L min-1, sampling heads for 0.5, 1 and 10 L min-1 were developed. Tests were conducted on these sampling heads, which all showed compliance with the requirements defined for inhalable fraction sampling. For the combined sampling of aerosol and vapour, a system was created which allows a filter and up to three usual adsorption tubes to be loaded simultaneously. The measuring methods for alkanolamines, inorganic acids and explosives are described to illustrate the use of the above PGP extensions and the framework conditions, account of which must be taken in the sample treatment.

Biochemical characterization and subcellular localization of the mouse retinitis pigmentosa GTPase regulator (mRpgr)

The retinitis pigmentosa GTPase regulator (RPGR) gene encodes a protein homologous to the RCC1 guanine nucleotide exchange factor and is mutated in 20% of patients with X-linked retinitis pigmentosa. We have characterized the full-length and variant cDNAs corresponding to the mouse homolog of the RPGR gene (mRpgr). Comparison with the human cDNA revealed sequence identity primarily in the region of RCC1 homology repeats. As in humans, the mRpgr gene maps within 50 kilobases from the 5'-end of the Otc gene. The mRpgr transcripts are detected as early as E7 during embryonic development and are expressed widely in the adult mice. Variant mRpgr isoforms are generated by alternative splicing and by utilizing two in-frame initiation codons. The products of mRpgr cDNAs migrate aberrantly in SDS-polyacrylamide gels because of a charged domain. In transfected COS cells, the mRpgr protein is isoprenylated and is localized in the Golgi complex. This subcellular distribution is not observed after treatments with brefeldin A or mevastatin and when the conserved isoprenylation sequence (CTIL) at the carboxyl terminus is deleted or mutagenized. These studies suggest a role for the mRpgr protein in Golgi transport and form the basis for investigating the mechanism of photoreceptor degeneration in X-linked retinitis pigmentosa.

[Assessment of problem situations in the family]

Goal of the study is the analysis of the German version of Barkle's Home Situations Questionnaire. The analysis is accomplished in a clinical sample of N = 76 children at the age of six to ten years with the diagnosis of a hyperkinetic disorder according to ICD-10 or an Attention deficit-/hyperactivity disorder according to DSM-III-R and in a representative sample of N = 263 children aged seven to ten years. Parents of hyperkinetic children experience many family situations with their child as very problematic which is essentially more often than parents in the representative sample. Analyses of the factorial structure of the questionnaire yielded no clear and well interpretable solutions. The instrument has a good internal consistency. The HSQ-D scores correlate significantly with other parent questionnaires for the assessment of behaviour problems, the highest correlations were found with scales for the assessment of hyperkinetic behaviour problems and social problems. In the clinical practice the instrument has proven helpful within symptom-specific assessment of children with hyperkinetic and oppositional behavior disorders and for the planning of interventions.

Symmetrical dispersion compensation for standard monomode-fiber-based communication systems with large amplifier spacing

Optical 10-Gbit / s return-to-zero pulse transmission in cascaded communication systems using dispersion compensation of the standard monomode fiber with large amplifier spacing is examined. It is shown that pulse distortions that are due to Kerr nonlinearity are significantly diminished by symmetrical ordering of the compensation sections when the total number of precompensation and postcompensation sections is equal. Repositioning of these sections is not critical.

[Development assessment of a hip ultrasonographic screening program for the early diagnosis of congenital hip dysplasia at the orthopedic university department Homburg/Saar from 1986 to 1990]

The results of the hip ultrasound newborn screening at the orthopaedic department of the University Hospital Homburg/Saar underline the necessity of an early diagnosis of Hip dysplasia already during the first days of life. In the course of the following publication the benefit of using abduction-pants in case of physiological unripe and primary pathological hips is described closely. From October 1985 to December 1990 2317 newborns have been examined by ultrasound. The rate of Hip Dysplasia (type IID, IIg, IIIa) was at 104 hips (2.2%). Clinical striking facts were only found in 46.3% of all patients with primary pathological hips. After an precautionary broad swadling (Breitwickeln) or abduction-pants-treatment 331 (90.0%) hips of the 368 regular checked hips with type IIa developed with an average secondary anatomical healing of 2.5 months to Ia- or Ib-hips. After 3 months only just 12 hips corresponded to a diagnosis of type IIb according to Graf. A deterioration to a IIg or IIIa hip was only ascertained in two cases. With all 41 sufficiently controlled primary pathological hips an improvement to type Ia or Ib according to Graf achieved when treated with abduction pants (average duration of treatment: 4.3 months). None of the children had to undergo an operation because of instable hips.

Activation of the phosphatidylinositol cycle in spreading cells

Metabolites of the phosphatidylinositol cycle were analyzed in BHK-21 (C13) cells spreading on fibronectin-coated culture plates in comparison with attached nonspreading cells 45 min after plating. Among the water-soluble metabolites (glycerophosphoinositol, inositol, inositol monophosphate, inositol bisphosphate, inositol trisphosphate, and inositol tetrakisphosphate), significant elevations were found for inositol monophosphate, inositol bisphosphate, and inositol tetrakisphosphate. In the lipid fraction, phosphatidylinositol 4-monophosphate and phosphatidylinositol 4,5-bisphosphate were significantly elevated. The activation of the phosphatidylinositol cycle in spreading versus nonspreading attached BHK-21 (C13) cells may be involved in the permissive effect of the extracellular matrix on cell proliferation.