River, reservoir and lake sediment contamination by heavy metals downstream from urban areas of Switzerland

This paper quantifies sediment contamination by heavy metals in four reservoirs and one lake located downstream from major urban areas in Switzerland. The waterbodies include the Wettingen Reservoir (located on the Limmat River downstream from Zürich), the Klingnau Reservoir (on the lower Aare River), the Wohlen Reservoir (downstream from Berne), the Verbois Reservoir (downstream from Geneva) and Vidy Bay (Lake Geneva, city of Lausanne). For all sediment cores and contaminants, a trend is observed from high contaminant values in the lower part of the cores, decreasing to lower concentrations in the upper part of the cores. However, for each site and each element, specific features are recognized. Applying the criteria of the Swiss ordinance on soil protection, all sediment cores must be classified as contaminated by one or more contaminants and at variable levels. From these data, it is concluded that: reservoirs and lakes located downstream from major urban centres in Switzerland have accumulated significant volumes of contaminated sediments in the past, representing the largest, but not the most intensely, contaminated sites on a national scale; the main environmental risk is remobilization of the contaminants and their return to the food chain, particularly by infiltration into the groundwater; and although the processes of remobilization are identified, the conditions of occurrence and the amplitude of the processes are still poorly known. Different options of reservoir and lake sediment management also are discussed and further research topics defined.     

An experimental study on iterative methods to compute transient solutions of large Markov models

In this article, we report results of an experimental study on six iterative methods to compute the transient probabilities of large Markov models: full matrix exponentiation, forward Euler method, explicit Runge-Kutta methods of order 2 and 4 and Adams-Bashforth multi-steps methods of order 2 and 4. We suggest a simple but efficient implementation of these algorithms. We discuss how to tune their few parameters. We present experimental results that contradict the literature.     

Lattice Reduction: A Toolbox for the Cryptanalyst

In recent years, methods based on lattice reduction have been used repeatedly for the cryptanalytic attack of various systems. Even if they do not rest on highly sophisticated theories, these methods may look a bit intricate to practically oriented cryptographers, both from the mathematical and the algorithmic point of view. The aim of this paper is to explain what can be achieved by lattice reduction algorithms, even without understanding the actual mechanisms involved. Two examples are given. One is the attack devised by the second author against Knuth's truncated linear congruential generator. This attack was announced a few years ago and appears here for the first time in complete detail. Received 19 May 1994 and revised 31 December 1997     

Pharmacokinetics and Tissue Uptake of Doxorubicin Associated With Erythroctte-nembrane:erithroctte-Ghosts vs Erythrocyte-Vesicles

This study examined the usefuless of erythrocyte-membrane as a biodegradable carrier for intravenous injection of doxorubicin (DOX). Two different preparations of erythrocyte-membrane were used, erythrocyte-ghosts and erythrocyte-vesicles. Ghosts were prepared from red blood cells by hemolysis and repetitive washing until complete removal of hemoglobin. Erythrocyte-vesicles were prepared by ultrasonication of the ghosts suspension by a sonic dismembrator. The membrane products were then incubated with DOX before the injection. In CD rats, the disposition of DOX solution (DOX in normal saline) and erythrocyte-vesicles-DOX followed a two-compartment open model, whereas the ghosts-DOX exhibited a three-compartment characteristics. The area under the curve of the amount in the heart vs time for ghosts-DOX was approximately the same as for the solution. However, the amount of DOX in the heart after erythrocyte-vesicles-DOX injection was below the sensitivity of the detection. The fraction of DOX excreted unchanged in the urine was 0.54 for ghosts-DOX, 0.22 for DOX solution and 0.06 for erythrocyte-vesicles-DOX. The uptake of the drug by the spleen was increased after the administration of erythrocyte-vesicles-DOX. The observed and the calculated data address the usefulness of these delivery systems for DOX.     

Fibroblast growth factor 3, a protein with dual subcellular localization, is targeted to the nucleus and nucleolus by the concerted action of two nuclear localization signals and a nucleolar retention signal

The major isoform of fibroblast growth factor 3 (FGF3) is initiated from a CUG codon, and the resultant product is distributed to the nucleus/nucleolus and secretory pathway. This dual subcellular localization is achieved in part by the competing effects of two classical intracellular targeting signals located near the amino terminus. At the extreme amino terminus is a short stretch of 29 amino acids before a signal peptide necessary for translocation into the endoplasmic reticulum, which is next to an adjacent bipartite nuclear localization signal. The carboxyl-terminal region of FGF3 is also implicated in nuclear/nucleolar localization. We describe here the characterization of carboxyl-terminal signals by showing they are capable of directing a heterologous protein, beta-galactosidase, to the nucleus. Furthermore, appending both the amino- and carboxyl-terminal domains onto beta-galactosidase, reproduces the dual subcellular localization properties of FGF3. Nuclear uptake of FGF3 appears to be signal-mediated since it binds to karyopherin alpha, the nuclear localization signal binding subunit of a heterodimeric receptor of the nuclear import machinery. The import of FGF3 into the nucleus is energy-dependent, and the inhibition of this process has demonstrated the importance of the nucleolar retention signal in nucleoplasmic and nucleolar accumulation.     

The role of telecommunications in economic development

Annals of Telecommunications - Les télécommunications ont connu un développement soutenu depuis plus de vingt ans. La diffusion des services a toujours été sensible à...