Alternating,all-trans polyenynes: Model compounds for poly(diacetylene)s with defined conjugation length

The syntheses of polyenynes as model compounds for poly(diacetylene)s (PDAs) are described. Variation of properties (UV–VIS, Raman, NMR and bond geometries) as a function of the chain length was investigated. After extrapolation to infinite chain length these data were compared to those for PDAs. From UV–VIS spectra a value of λ = 551 nm (2.25 eV) was calculated corresponding to the electronic transition of a single polyenyne chain. This energy is located at the low energy end of a yellow PDA solution spectrum. From Raman scattering v_(C?C) = 2108–2128 cm^?1 and v_(C?C) = 1505–1532 cm^?1 were calculated after extrapolation. Similarly sp-C¹³C NMR data yielded a shift of δ = 100 ppm. These data are almost identical to data known for yellow PDA solutions. Bond geometries are almost identical to those of poly(diacetylene)s and theoretical data.     

Tests and Proofs

This special issue collects current advances in the ongoing attempt to obtain synergies from the combination of Tests and Proofs.     

On Design of Parallel Memory Access Schemes for Video Coding

Some of the modern powerful digital signal processors (DSPs) have byte-addressable internal data memory. This property is valuable especially in computationally demanding inter frame video encoding, where data accesses are typically unaligned according to word boundaries. The byte-addressable memory allows load or store command to start accessing from any byte-address, providing at most as many successive bytes from subsequent addresses as data bus can handle in parallel. Maybe the simplest way to construct such a byte-addressable memory is to use N 8-bit memory modules or banks to be accessed in parallel, when N is data bus width in bytes. However, in addition to byte-addressable subsequent bytes, memory consisting of parallel memory modules can provide much more versatile addressing capabilities with reasonable implementation cost. Versatile access formats can significantly reduce the need for data reordering in the register file. At first, we provide motivation for using parallel memory architecture with versatile access formats as an internal on-chip data memory of modern DSP. After this, notations are described and general view of parallel memory design is given. We propose some example parallel data memory architecture designs with data access formats especially helpful in H.263 encoding and MPEG-4 core profile motion and texture encoding. The examples are given for different data bus widths (16, 32, 64, and 128 bits). Finally, performance is shortly compared to other memory architectures and area, delay, and power figures are estimated.Jarno K. Tanskanen was born in Joensuu, Finland in 1975. He studied analog and digital electronics in the Department of Electrical Engineering, and computer architecture in the Department of Information Technology at Tampere University of Technology, where he received his M.Sc. degree in 1999. He is currently working as a research scientist in the Institute of Digital and Computer Systems at TUT. His Dr.Tech. research concerns parallel processing of video compression. jarno.tanskanen@tut.fiReiner Creutzburg received his Diploma in Mathematics in 1976 and attained his Ph.D. in Mathematics in 1984 from the Rostock University, Germany. Prof. Creutzburg has published 3 books, filed 2 patents, and produced approximately 100 articles, preprint, and conference papers. Professional Experience: Since 2000—Part-time Professor for Multimedia technology, Tampere University of Technology, Finland. Since 1992—Full-time Professor of Computer Science, Fachhochschule Brandenburg-University of Applied Sciences, Brandenburg, Germany. 1990 to 1992—Assistant Professor, University of Karlsruhe, Institute of Algorithms and Cognitive Systems, Germany. 1987 to 1989—Head of the Research Section Image Processing. 1986 to 1989—Founder and Head of the International Base Laboratory of Image Processing and Computer Graphics for East European countries at the Central Institute of Cybernetics and Information Processes of the Academy of Sciences (Berlin), Germany. 1976 to 1989—Researcher and Assistant Professor in various Universities and the Academy of Sciences, Central Institute of Cybernetics and Information, Berlin. creutzburg@fh-brandenburg.deJarkko T. Niittylahti was born in Orivesi, Finland, in 1962. He received the M.Sc, Lic.Tech, and Dr.Tech degrees at Tampere University of Technology (TUT) in 1988, 1992, and 1995, respectively. From 1987 to 1992, he was a researcher at TUT. In 1992–93, he was a researcher at CERN in Geneva, Switzerland. In 1993–95, he was with Nokia Consumer Electronics, Bochum, Germany, and in 1995–97 with Nokia Research Center, Tampere, Finland. In 1997–2000, he was a Professor at Signal Processing Laboratory, TUT, and in 2000–2002 at Institute of Digital and Computer Systems, TUT. Currently, he is a Docent of Digital Techniques at TUT and the managing director of Staselog Ltd. He is also a co-founder and President of Atostek Ltd. He is interested in designing digital systems and architectures. jarkko.niittylahti@tut.fi     

A Markov-Based Channel Model Algorithm for Wireless Networks

Techniques for modeling and simulating channel conditions play an essential role in understanding network protocol and application behavior. In [11], we demonstrated that inaccurate modeling using a traditional analytical model yielded suboptimal error control protocol parameters choices. In this paper, we demonstrate that time-varying effects on wireless channels result in wireless traces which exhibit non-stationary behavior over small window sizes. We then present an algorithm that extracts stationary components from a collected trace in order to provide analytical channel models that, relative to traditional approaches, more accurately represent characteristics such as burstiness, statistical distribution of errors, and packet loss processes. Our algorithm also generates artificial traces with the same statistical characteristics as actual collected network traces. For validation, we develop a channel model for the circuit-switched data service in GSM and show that it: (1) more closely approximates GSM channel characteristics than traditional Markov models and (2) generates artificial traces that closely match collected traces' statistics. Using these traces in a simulator environment enables future protocol and application testing under different controlled and repeatable conditions.     

Optimization of planar Be-doped InGaAs VCSEL's with two-sidedoutput

Threshold current, output power, wall-plug efficiency and operating voltage of epitaxially grown InGaAs-AlGaAs planar vertical-cavity surface-emitting lasers (VCSEL's) are strongly influenced by the electrical and optical properties of the p-doped Bragg reflector. Here we study in some detail the dependence of output behavior on the composition, interface grading, and modulation doping of the Be-doped AlGaAs-GaAs Bragg reflector. Using optimized p-doped mirrors VCSEL's with low threshold current densities of 300 A/cm² , low driving voltages of 1.6 V and high wall-plug efficiencies of 17.6% are obtained. Transverse single-mode emitting devices show a record low emission linewidth of 30 MHz and a linewidth-power product of 2.2 mW·MHz     

Real structure of partially ordered crystals

Partial order in crystals is a frequently observed phenomenon in minerals and synthetic materials. The partially ordered structures are characterized by low-dimensional order of the real structure. In the case of 1D structures, the ordered units can be described as rods; 2D structures contain ordered layers. The disorder of the real structures is indicated by prominent diffuse scattering in the diffraction patterns of single crystals. No simple method for the quantitative analysis of the diffuse scattering exists, therefore the determination of essential characteristics of the structures is complicated. However, the determination can be facilitated using a combination of different methods, including electron microscopy, computation and X-ray diffraction.     

Action of prostaglandin, PGF2alpha, on the uterus of the pregnant rat

In a cytogenetic study on the spermatogonia of Chinese hamster, cyclohexylamine (neutral sulphate) was evaluated for mutagenic effects in comparison with an untreated control group and a group treated with the mutagenic compound cyclophosphamide, by assessing spermatogonial metaphases of treated Chinese hamster for chromosomal structural changes. Each test group comprised 8 male hamsters selected at random. Approximately 100 metaphases from each animal were assessed. The doses were 5 X 150 mg cyclohexylamine sulphate (approx. 5 X 102 mg base) per kg body-weight orally, and 5 X 100 mg cyclophosphamide per kg body-weight orally. The individual doses were administered at intervals of 24 h. Preparations were made 24 h after the final treatment, essentially by the method of Hoo and Bowles [10]. Gaps, breaks, fragments, deletions and translocations were assessed as structural changes; frequencies were determined of the metaphases (a) with aberration(s) including gaps, (b)with aberration(s) less gaps and (c)with translocation(s). Aberrations occurred in the untreated negative control group (1.24% incl. gaps, 0.25% without gaps). Translocations were not seen in the untreated group. In the cyclochexylamine group, the frequencies of the aberrant metaphases were sometimes less than in the control group (0.87% including gaps, 0.37% without gaps). Statistically, the results were not significantly different from the control data. No translocations were seen after administration of cyclohexylamine. The positive cyclophosphamide control group clearly differed from the untreated control and from the cyclohexylamine group in the parameters (a) to (c); mainly, the results were highly significantly different from those obtained in the untreated control group. The frequencies of the aberrant metaphases were 3.41% including gaps and 1.99% without gaps. The frequency of the translocations was 0.71% (5 out of 704). Cyclohexylamine sulphate, administered 5 times at 150 mg/kg body-weight orally, had no mutagenic effect, whereas cyclophosphamide, adminstered 5 times at 100 mg/kg body-weight orally, had a chromosome-damaging effect on Chinese hamster spermatogonia.     

Identification and evaluation of volatile odor-active pollutants from different odor emission sources in the food industry

In order to elucidate the nature of different odor-emission sources in the food industry, odor-active pollutants of the exhaust air in the cooling gases from coffee bean roasting, the exhaust air of fish meal production, and the exhaust air of swine breeding were investigated. Knowledge of what pollutants are present in the odor emission and are responsible for the malodor is vital to the development of suitable adsorbers/absorbers and filters, and combinations of the same. Therefore, the objective of these investigations was to identify and evaluate the characteristic impact of compounds in the exhaust air of these odor-emission sources. The volatile compounds were collected by using a microprocessor-controlled gas sampler through sorbent tubes of Tenax TA. The adsorbed compounds were analyzed by thermal desorption into a cryotrap and subsequent gas chromatography separation, followed by simultaneous olfactometry and mass spectrometry. In cooling gases of the coffee bean roasting numerous compounds (up to 100) were identified of which only 22 were important for the characteristic odor. These compounds were aldehydes (2-methyl propanal, 2- and 3-methyl butanal, 2-furancarboxyaldehyde, 5-methyl-2-furancarboxyaldehyde), diketones (2,3-butandione, 2,3-pentandione), pyrazines, pyridine, acetic acid, and furanmethanol. Other compounds with low concentrations but with a very low odor threshold and, therefore, important for the total odor were 3-methyl butanoic acid and guaiacol. Up to 50 compounds were identified in the exhaust air of fish meal production, the most significant of these being trimethylamine. Trimethylamine, with a very low odor threshold (0.0025 g/l air) and the highest content (up to 60% in the total ion chromatogram, more than 100 g/l) in the exhaust air of fish meal production, was responsible for the characteristic fishy odor. Beside trimethylamine only a few compounds, e.g., sulfides (dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide), aldehydes (2-methyl propanal, 2- and 3-methyl butanal), ethanol, and guaiacol, played a secondary role for the total odor. In the exhaust air of the pig house up to 50 compounds were identified. Beside ammonia, the most important odor-active compounds were various carboxylic acids (acetic acid, butanoic acid, 3-methyl butanoic acid), sulfides (dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide), trimethylamine, and the intensive odor-active p-cresol and 4-ethylphenol.     

Characterization of iron(III) in organic soils using extended X-ray absorption fine structure spectroscopy

The distribution of different iron (Fe) species in soils, sediments, and surface waters has a large influence on the mobility and availability of Fe, other nutrients, and potentially toxic trace elements. However, the knowledge about the specific forms of Fe that occurs in these systems is limited, especially regarding associations of Fe with natural organic matter (NOM). In this study, extended X-ray absorption fine structure (EXAFS) spectroscopy was used to characterize Fe(III) in organic soils (pH 4.6-6.0) with varying natural Fe content. The EXAFS data were subjected to wavelet transform analysis, to facilitate the identification of the nature of backscattering atoms, and to conventional EXAFS data fitting. The collective results showed the existence of two pools of iron: mononuclear Fe(III)-NOM complexes and precipitated Fe(III) (hydr)oxides. In the soil with lowest pH (4.6) and Fe content mononuclear organic complexes were the completely dominating fraction whereas in soils with higher pH and Fe content increasing amounts of Fe (hydr)oxides were detected. These results are of environmental importance, as the different iron pools most likely have markedly different reactivities.