Lake Vostok, East Antarctica, represents an extensive water surface at the base of the ice sheet. Snow, ice and atmospheric pressure loads applied anywhere within the lake area produce a hydrostatic response, involving deformations of the ice surface, ice–water interface and particle horizons. A modelling scheme is developed to derive height changes of these surfaces for a given load pattern. It is applied to a series of load scenarios, and predictions based on load fields derived from a regional climate model are compared to observational datasets. Our results show that surface height changes due to snow-buildup anomalies are damped over the lake area, reducing the spatial standard deviation by one-third. The response to air pressure variations, in turn, adds surface height variability. Atmospheric pressure loads may produce height changes of up to $\pm$4 cm at daily resolution, but decay rapidly with integration time. The hydrostatic load response has no significant impact neither on ICESat laser campaign biases determined over the lake area nor on vertical particle movements derived from GNSS observations.

We investigate theoretically, on the basis of the steady Stokes equations for a viscous incompressible fluid, the flow induced by a stokeslet located on the centre axis of two coaxially positioned rigid disks. The stokeslet is directed along the centre axis. No-slip boundary conditions are assumed to hold at the surfaces of the disks. We perform the calculation of the associated Green's function in large parts analytically, reducing the spatial evaluation of the flow field to one-dimensional integrations amenable to numerical treatment. To this end, we formulate the solution of the hydrodynamic problem for the viscous flow surrounding the two disks as a mixed boundary-value problem, which we then reduce to a system of four dual integral equations. We show the existence of viscous toroidal eddies arising in the fluid domain bounded by the two disks, manifested in the plane containing the centre axis through adjacent counter-rotating eddies. Additionally, we probe the effect of the confining disks on the slow dynamics of a point-like particle by evaluating the hydrodynamic mobility function associated with axial motion. Thereupon, we assess the appropriateness of the commonly employed superposition approximation and discuss its validity and applicability as a function of the geometrical properties of the system. Additionally, we complement our semi-analytical approach by finite-element computer simulations, which reveals a good agreement. Our results may find applications in guiding the design of microparticle-based sensing devices and electrokinetic transport in small-scale capacitors.

We analyze and compare the impact of tax incentives and of introducing enhanced annuities on annuitization behavior considering heterogeneity among the insured. We find that tax incentives for annuitization result in a significant increase of the portion of people who should annuitize and also an increase of the insurer's profit since less healthy individuals also annuitize, i.e. adverse selection is reduced. However, the problem that different insured receive a different value for money is even increased by tax incentives. If enhanced annuities are introduced, the percentage of insured who should annuitize further increases. Adverse selection is further reduced and the differences in value for money from annuitizing shrink.

An overview about the German cluster project Cool Silicon aiming at increasing the energy efficiency for semiconductors, communications, sensors and software is presented. Examples for achievements are: 1000 times reduced gate leakage in transistors using high-fc (HKMG) materials compared to conventional poly-gate (SiON) devices at the same technology node; 700 V transistors integrated in standard 0.35 μm CMOS; solar cell efficiencies above 19% at < 200 W/m2 irradiation; 0.99 power factor, 87% efficiency and 0.088 distortion factor for dc supplies; 1 ns synchronization resolution via Ethernet; database accelerators allowing 85% energy savings for servers; adaptive software yielding energy reduction of 73% for e-Commerce applications; processors and corresponding data links with 40% and 70% energy savings, respectively, by adaption of clock frequency and supply voltage in less than 20 ns; clock generator chip with tunable frequency from 83-666 MHz and 0.62-1.6 mW dc power; 90 Gb/s on-chip link over 6 mm and efficiency of 174 fJ/mm; dynamic biasing system doubling efficiency in power amplifiers; 60 GHz BiCMOS frontends with dc power to bandwidth ratio of 0.17 mW/MHz; driver assistance systems reducing energy consumption by 10% in cars

Genetic disturbances in folate metabolism may increase risk for congenital heart defects. We examined the association of heart defects with four polymorphisms in folate-related genes (methylenetetrahydrofolate reductase (MTHFR) c.677C > T, MTHFR c.1298A > C, methionine synthase reductase (MTRR) c.66A > G, and reduced folate carrier (SLC19A1) c.80A > G) in a case–control study of children (156 patients, 69 controls) and mothers of children with heart defects (181 patients, 65 controls), born before folic acid fortification. MTRR c.66A > G in children modified odds ratios for overall heart defects, specifically ventricular septal defect and aortic valve stenosis (p-value below 0.05). The 66GG and AG genotypes were associated with decreased odds ratios for heart defects (0.42, 95% confidence interval (0.18–0.97) and 0.39 (0.18–0.84), respectively). This overall association was driven by decreased risk for ventricular septal defect for 66GG and AG (odds ratio 0.32 (0.11–0.91) and 0.25 (0.09–0.65)) and decreased odds ratio for aortic valve stenosis for 66AG (0.27 (0.09–0.79)). The association of ventricular septal defect and 66AG remained significant after correction for multiple testing (p = 0.0044, multiple testing threshold p = 0.0125). Maternal MTHFR 1298AC genotype was associated with increased odds ratio for aortic valve stenosis (2.90 (1.22–6.86), p = 0.0157), but this association did not meet the higher multiple testing threshold. No association between MTHFR c.677C > T or SLC19A1 c.80A > G and heart defect risk was found. The influence of folate-related polymorphisms may be specific to certain types of heart defects; larger cohorts of mothers and children with distinct sub-classes are required to adequately address risk.

Raffinose family oligosaccharides (RFOs) are of almost ubiquitous occurrence in plant seeds. They accumulate during seed development and disappear rapidly during germination. The biosynthesis of raffinose, the first member of the series, proceeds by addition of a galactosyl unit to sucrose. Galactinol, a galactosyl derivative of myo-inositol, acts as a galactosyl donor. It is synthesized from UDP-D-GALACTOSE AND MYO-INOSITOL. STACHYOSE, VERBASCOSE AND AJUGOSE, THE NEXT HIGHER RFOS, ARE EITHER SYNTHESIZED BY GALACTINOL-DEPENDENT GALACTOSYLTRANSFERASES OR BY TRANSFER OF GALACTOSYL UNITS BETWEEN TWO RFO MOLECULES. IN SEEDS, THE METABOLISM OF METHYLATED INOSITOLS, SUCH AS D-ononitol and D-pinitol, is linked with the RFO pathway. In contrast to myo-inositol, these cyclitols are galactosylated by transfer of galactosyl residues from galactinol and not from UDP-D-galactose. However, the resulting galactosyl cyclitols can replace galactinol as galactosyl donors for the biosynthesis of stachyose. These recently discovered branches of the RFO pathway are active in seeds of a range of crop species, especially in legumes. We focus here on the biochemistry and molecular biology of the enzymes of RFO and galactosyl cyclitol biosynthesis. The metabolic control and hormonal regulation of the pathway during seed development and germination is discussed. The controversial role of α-galactosidases, which are believed to hydrolyse RFOs during germination, is reviewed critically.

The mechanical properties of thin metal films as compared to their bulk counterparts have been in the focus of materials science in the recent years. Owing to their technological importance, almost only metals with a face centered cubic structure like copper and aluminum have attracted scientific interest. Thin films made of bcc metals, on the other hand, have been largely neglected.

However, from a scientific point of view, the mechanical properties of bcc metals are of special interest. As an example, the yield stress of bcc metals is strongly temperature dependent for low temperatures, while it shows a behavior similar to fcc metals for higher temperatures. This is often referred to as the brittle to ductile transition (BDT). Despite intense research the underlying mechanisms leading to this phenomenon are still not understood in full detail. A major problem is the understanding of dislocation dynamics on the microscopic scale, which is different from that of fcc metals because of the special symmetry of the crystal system.

A first step is to verify in thin films that for temperatures above the BDT the thermomechanical behavior of bcc metals resembles that of fcc metals. As a model system we chose iron with a BDT temperature slightly above room temperature. We deposited iron by means of an MBE system on sapphire substrates. The so-produced epitaxial thin iron films with thicknesses above 50 nm were then thermally cycled from room temperature to 540°C in a vacuum substrate curvature apparatus to test their thermomechanical behavior.

We will present the results of substrate curvature measurements performed with iron films of different thicknesses and discuss similarities and differences to results obtained for metals with fcc crystal structures.

Self-assembled InAs quantum dots (QDs) on GaAs substrate encapsulated with In0.15Ga0.85As1−xNx (GINA) have been grown by solid source molecular beam epitaxy, using optimal growth temperatures and rates for each of the two layers. The photoluminescence (PL) intensity increases for annealed samples. The optimum annealing temperature depends on the nitrogen composition. InAs QDs overgrown with larger nitrogen mole fraction GINA show a smaller PL peak blue-shift after annealing. Intense and narrow PL emission in the 1.5 µm range is achieved for samples annealed at optimal temperature.

To interpret H2 quasar absorption line observations in DLAs (damped Lyα clouds), we model the H2 spatial distribution within a DLA. Based on numerical simulations of disk structures with parameters similar to those derived for such absorbers, we calculate the H2 distribution as a function of ultraviolet background (UVB) intensity and dust-to-gas ratio. For typical values of these two quantities we find that the area in which the H2 fraction exceeds 10−6 (typical observational detection limit) only covers < 10% of the disk surface, i.e., H2 has a very inhomogeneous, clumpy distribution even at these low abundance levels. This explains the relative paucity of H2 detections in DLAs. We also show the dependence of the covering fraction of H2 on dust-to-gas ratio and UVB intensity and we comment on the physics governing the H2 chemical network at high redshift. We finally comment on our implication on the statistics of the H2 column density distribution.

Indoor air contamination with mould spores currently experiences an increasing interest with respect to their relevance to health. To assess adverse health effects, epidemiological studies combine the health outcome of individuals with their concomitant exposure to airborne spores, which is observed, for example, during the current month. While the latter is representative for the studied period, health effects might also be the result of long term-exposure or emerge in consequence of a peak of pollution throughout the year. To consider such questions, additional information about the spatiotemporal distribution of airborne spores is necessary.

This paper aims at elucidating the spatial and temporal variation of spore concentrations in Leipzig, Germany. The analysis is based on 1165 matched pairs of indoor and outdoor measurements taken in the period 1998–2002. All data were collected in the frame of previous epidemiological studies and refer to apartments. The analysis comprised spore concentrations (as CFU m−3 in air) of the most important genera, such as Penicillium, Aspergillus, Alternaria, Mucorales, Cladosporium, and also for yeasts.

We found two groups of fungi differing in their spatiotemporal distribution. As this behaviour can be explained by the predominant origin and growing conditions, we call them indoor-relevant and outdoor-relevant genera. Penicillium species are a representative of the former group, while the latter is well represented by Cladosporium. In the studied period we did not observe a clear trend in the spore concentration. Outdoors there is a year-to-year variation of Cladosporium spore concentrations, which follow the prevalent climatic conditions.

For the spore concentration of the outdoor-relevant group a significant annual cycle was observed. Highest concentrations occurred during the summer months and were about 100× the winter burden. That means, for a direct comparison of measurements of spore concentrations taken during different months the season has to be considered. We summarise the findings in a seasonal model, which is fitted to our measurements. Based on the model we developed a procedure for seasonal adjustment, which enabled us to estimate the annual peak spore concentration utilising one monthly observation.