New threats and attacks on the World Wide Web

Ten years ago, very few networks had a firewall; today, they're ubiquitous. The newest target is the workstation: client-side attacks have increased because direct attacks on servers aren't so easy any more. Moreover, as new defenses are raised, information flows are increasingly embedded into Web applications, making them extremely valuable as well, and, thus, the next target. This article describes some of these new threats.     

Conversion of ethanol over metal-exchanged zeolites

The effects of metal exchange between zeolites and alkali metals (Li, Na, K; zeolite Y, ZSM-5, T), alkaline earths (Mg, Ca, Sr, Ba; ZSM-5), transition metals (La, Ce, Cr, Mn, Fe, Co, Ni, Pd, Cu, Zn; ZSM-5) and aluminium (ZSM-5) on the conversion of ethanol were studied. Activities of the catalysts and selectivities for ethene, C₃₊ olefins, paraffins and arenes strongly depended on the cation, chosen for the modification. Only ethene was formed by alkali exchanged zeolites, the most active being Li-Y. This could be confirmed by a long-term ageing test with Li-Y pellets under semi-industrial conditions. The exchange of ZSM-5 with alkaline earths or transition metals permitted the formation of a wide variety of products, raning from high ethene to high aromatic yields. A correlation between certain product selectivities and electronegativity was only possible in a rough approximation.     

Der Einfluß von Temperaturgradienten auf das dilatometrische Verhalten von unlegierten Eisenwerkstoffen mit niedrigem Kohlenstoffgehalt im Verlauf der α-γ-Umwandlung

Kontinuierliche Aufnahme der Längenänderung von reinem Eisen, Armco-Eisen und Stahl St 35.8 im Verlauf der α-γ-α-Umwandlung in Abhängigkeit vom Temperaturgradienten zwischen 0 und 35°C/cm. Deutung der Meßergebnisse mit Hilfe der ebenen Phasengrenzfläche. Bleibende Längenänderung nach mehrfachem Durchlaufen der Phasenumwandlung und deren Deutung.     

Die spezifische Wärmekapazität von metallischen Werkstoffen. – I. Teil: Ferritische,umwandlungsfähige Stähle

Beschreibung des verwendeten adiabatischen Hochtemperaturkalorimeters. Wahre und mittlere spezifische Wärmekapazität zwischen 50 und 400 bzw. 650°C der Stähle St 35, 13 CrMo 4 4, 10 CrMo 9 10, X 20 CrMoV 12 1, 12 Ni 19 und X 8 Ni 9. Ergänzende Untersuchungen an dem ferritisch-austenitischen Stahl X 20 CrNiSi 25 4. Aufspaltung der Meßwerte in den Anteil nach Debye sowie in den anharmonischen, elektronischen und magnetischen Beitrag zur spezifischen Wärmekapazität.     

Prüfung von Flanschverbindungen in GFK-Rohrleitungen NW 200 durch Kurz- und Langzeitbeanspruchung – Teil I: Dichtverhalten

Testing of flanged joints in GRP pipelines of 200 mm nominal diameter by means of short-term and long-term stressing. Part I: Sealing behaviour . The first part of this report deals with the sealing behaviour of joints with fixed and loose flanges in GRP pipelines of 200 mm nominal diameter. Tests were made with seven different flanges from three manufacturers and four different types of sealing rings. At room temperature the spring rate of the GRP flanges amounted to between 8% and 18% of that of welded steel flanges and at a temperature of 80°C within the pipe it was 5% to 16% of that of the steel flanges. Of the sealing rings tested a bulged soft rubber ring with steel reinforcement was found to have the flattest resilience characteristic and required the least bolt force to produce a tight joint under operational conditions. Its relaxation rate was low after low bolt force had been applied and increased rapidly when the initial bolt force was increased to higher values. Because of their lower spring rates, the GRP flanges sealed with this ring required 2.5 to 3.5 times as much initial bolt force as welded steel flanges. In an 1100-hour creep test at 80°C internal temperature and 10 bar internal pressure, a joint consisting of loose steel flanges and GRP shoulders exhibited considerably less loss of initial force than a fixed GRP flanged joint. Because losses of initial force increase at a disproportionately high rate as the force is raised, high initial force would not seem to increase remarkably the reliability of the seal in the long term. Since rigid flanges require less initial force than less rigid ones, high spring rate appears desirable. Apparently it could best be achieved by loose steel flanges with GRP shoulders. The results of the strength tests will be presented in the second part of this report.     

An automated photometric method for determining niacin and niacinamide content in grain and cereals

The subject of this report is an automated photometric method for the determination of the content of total niacin in grain and cereal food. The customary coupling reagent sulfanilic acid has been replaced by 1,3-dimethylbarbituric acid; CNCl is produced in the flow through system directly from KCN and chloramine T. The composition of reagents, the procedure and the analytical manifold are specified. 30 analyses/h can be performed. The accuracy and reproducibility of the automated method is good. In a range of 0.5-4.0 micrograms/ml niacin and a total content of 10-135 mg niacin/kg dry matter an average variation coefficient of vk = 0.74% (n = 10) was obtained. When lack of homogeneity of samples and variation in alkaline hydrolysis are included average vk to +/- 2.43% at the same range of niacin. The content of total niacin in various kinds of grain and in enriched ready to eat cereal foods was determined.     

Nachweis der Behandlung von Hühnerbrust mit ionisierenden Strahlen und Abschätzung der Bestrahlungsdosis mit Hilfe der Headspace-Gaschromatographie und diskriminanzanalytischer Auswertung

Chicken breast was irradiated with doses of 3, 5, and 7 kGy. Headspace gas chromatographical analysis demonstrated the tendency that the amounts of volatile compounds (mainly pentanal, hexanal and heptanal) are higher in irradiated samples in comparison with non irradiated. Statistical evaluation of the gas chromatograms by discriminant analysis enabled the detection of irradiation. Unknown samples could be classified in the groups ?unirradiated“ or ?irradiated in most cases.     

Die Wärmeausdehnung austenitischer Mangan- und Mangan-Chrom-Stähle

Dilatometrische Bestimmung des linearen Wärmeausdehnungskoeffizienten an fünf Manganstählen sowie sechs Mangan-Chrom-Stählen zwischen — 196 und 500°C. Einfluß der magnetischen Ordnung auf das Ausdehnungsverhalten. Ausdehnungsverhalten verschiedener Schmelzen bei vorgegebener Stahlqualität.     

Lower time bounds for integer programming with two variables

In this paper an elementary version of the integer programming problem is considered, namely that of deciding whether a given triangle in the plane contains a point with integer coordinates. We prove two lower bounds for the number of operations necessary to solve this problem: (i) Ω(p) steps are necessary if operations from {+, -,%,, ?} are admissible, (ii) Ω(log p) steps are necessary if operations from {+, -, ?·?, ?} are admissible. Here, p denotes the binary length of the input and ?·? denotes the floor function. New techniques are necessary for relating the bounds to the length of the input—known methods only yield uniform bounds assuming all real inputs to be allowed—and for handling the floor function which prevents us from applying the well-known algebraic arguments.The best known algorithm is due to H.W. Lenstra, Jr. (preprint) and needs O(p) steps over {+, -, 1, %, ?·?, ?} (P. van Emde Boas, 1984).