Sequence and function analysis of a 4·3 kb fragment of Saccharomyces cerevisiae chromosome II including three open reading frames

The nucleotide sequence of a fragment of 4337 base pairs of Saccharomyces cerevisiae chromosome II has been determined. The sequence contains three open reading frames, one of them being incomplete. Deletion analysis showed that YBR12.31 is essential for yeast growth, while deletion mutants of YBR12.32 and YBR12.33 are viable. YBR12.33 is identical to SMY2, isolated as a suppressor of a myo2 mutant (Lillie, S.H. and Brown, S.S., unpublished, EMBL M90654).     

Approximation of jump diffusions in finance and economics

In finance and economics the key dynamics are often specified via stochastic differential equations (SDEs) of jump-diffusion type. The class of jump-diffusion SDEs that admits explicit solutions is rather limited. Consequently, discrete time approximations are required. In this paper we give a survey of strong and weak numerical schemes for SDEs with jumps. Strong schemes provide pathwise approximations and therefore can be employed in scenario analysis, filtering or hedge simulation. Weak schemes are appropriate for problems such as derivative pricing or the evaluation of risk measures and expected utilities. Here only an approximation of the probability distribution of the jump-diffusion process is needed. As a framework for applications of these methods in finance and economics we use the benchmark approach. Strong approximation methods are illustrated by scenario simulations. Numerical results on the pricing of options on an index are presented using weak approximation methods.     

Synthesis of chemically bonded poly(vinyl alcohol)-starch composite

Poly(vinyl alcohol) (PVA) was grafted on hydrolysed starch through introduction of the chemically reactive bifunctional compound N-methylolacrylamid (N-MAm). The grafting reaction was carried out in two separate reaction steps. The first step was the reaction of PVA with N-MAm in alkaline medium. The reaction mechanism and reaction conditions such as alkali concentration, temperature, reaction time as well as N-MAm concentration were studied. According to the results obtained, the most appropriate conditions for the preparation of this reactive PVA are: treating PVA with N-MAm (1.25 mol/mol PVA) in the presence of NaOH (6% based on solution volume) at 20°C for 8 h. Second step was the reaction of this reactive PVA (N-MAm-PVA) with hydrolysed starch in the presence of NH₄Cl. The latter was carried out under different conditions including temperature, reaction time, catalyst concentration as well as N-MAm-PVA/hydrolysed starch ratio. The results obtained show that the extent of the grafting reaction is governed by each of these factors. Furthermore, GPC data showed that the molecular weight distribution and the apparent viscosity of PVA-N-MAm-starch composite depend on the initial molecular weight of both PVA and hydrolysed starch used.     

Sequence analysis of a 5·6 kb fragment of chromosome II from Saccharomyces cerevisiae reveals two new open reading frames next to CDC28

The sequence of a 5653 bp DNA fragment of the right arm of chromosome II of Saccharomyces cerevisiae contains two unknown open reading frames (YBR1212 and YBR1213) next to gene CDC28. Gene disruption reveals both putative genes as non-essential. ORF YBR1212 encodes a predicted protein with 71% similarity and 65% identity (total polypeptide of 376 aa) with the 378 aa Sur1 protein of S. cerevisiae, while the putative product of ORF YBR1213, which is strongly expressed, has 28% identity with a Lactococcus lactis-secreted 45 kDa protein and 24% identity with the Saccharomyces cerevisiae AGA1 gene product. The total sequence of the fragment has been submitted to the EMBL databank (accession number X80224).     

Emission control strategies for Turkey in view of an integration into the European community

As Turkey intends to join the European Community (EC), there is a need to adjust the national policies to the EC policies. As for the Turkish energy policies, supply strategies are needed that comply with the emission control regulations of the EC, taking into account the fast growing energy requirements and the increasing use of low-grade domestic fuels in Turkey, resulting in increasing air pollution. In a project carried out by the Institute for Industrial Production (IIP), Karlsruhe, in collaboration with the Gazi University, Ankara, and the responsible Turkish authorities, cost-efficient strategies are being developed to reduce emissions in Turkey according to the requirements. The project is financed by the Volkswagen-Stiftung, Hannover. By using the energy-environmental model EFOM-ENV as a tool, cost-efficient mixtures of technological emission control measures, including fuel switching, substitution of energy conversion technologies and the application of emission reduction technologies, are being determined to enable Turkey to comply with the emission control regulations of the EC. Selected results of this project are presented.     

Infrared temperature measurements on solar trough absorber tubes

The temperature distribution on solar trough absorber tubes determines thermal losses and hotspots can lead to material stress and limit absorber tube lifetime. The concentrated solar radiation, however, makes it difficult to determine the temperature on solar absorbers. Temperature sensors that require contact to the measurement object are not appropriate and even pyrometry fails, when external light sources interfere. Only solar-blind pyrometry offers reliable temperature readings without perturbation through reflected solar radiation. This paper presents two concepts for a pyrometric solar-blind measurement on solar trough absorber tubes. One solar-blind approach is a spectral measurement range in regions, where the solar spectrum shows gaps due to the discrete absorption of the atmosphere. Another possibility for a solar-blind pyrometric temperature measurement results from the optical behavior, i.e. the distinct angle dependence of the directional reflectance and emittance of a typical selective trough absorber coating. First experimental results are shown and the accuracy and performance advantages and disadvantages of the setups are reported and discussed.     

A population balance approach considering heat and mass transfer—Experiments and CFD simulations

Bubble condensation in sub-cooled water is a complex process, to which various phenomena contribute. Since the condensation rate depends on the interfacial area density, bubble size distribution changes caused by breakup and coalescence play a crucial role.Experiments on steam bubble condensation in vertical co-current steam/water flows have been carried out in an 8 m long vertical DN200 pipe. Steam is injected into the pipe and the development of the bubbly flow is measured at different distances to the injection using a pair of wire mesh sensors. By varying the steam nozzle diameter the initial bubble size can be influenced. Larger bubbles come along with a lower interfacial area density and therefore condensate slower. Steam pressures between 1 and 6.5 MPa and sub-cooling temperatures from 2 to 12 K were applied. Due to the pressure drop along the pipe, the saturation temperature falls towards the upper pipe end. This affects the sub-cooling temperature and can even cause re-evaporation in the upper part of the test section. The experimental configurations are simulated with the CFD code CFX using an extended MUSIG approach, which includes the bubble shrinking or growth due to condensation or re-evaporation. The development of the vapour phase along the pipe with respect to vapour void fractions and bubble sizes is qualitatively well reproduced in the simulations. For a better quantitative reproduction, reliable models for the heat transfer at high Reynolds number as well as for bubble breakup and coalescence are needed.