Scheduling data transfers in a network and the set scheduling problem

In this paper we consider the online ftp problem. The goal is to service a sequence of file transfer requests given bandwidth constraints of the underlying communication network. The main result of the paper is a technique that leads to algorithms that optimize several natural metrics, such as max-stretch, total flow time, max flow time, and total completion time. In particular, we show how to achieve optimum total flow time and optimum max-stretch if we increase the capacity of the underlying network by a logarithmic factor. We show that the resource augmentation is necessary by proving polynomial lower bounds on the max-stretch and total flow time for the case where online and offline algorithms are using same-capacity edges. Moreover, we also give polylogarithmic lower bounds on the resource augmentation factor necessary in order to keep the total flow time and max-stretch within a constant factor of optimum.     

Mechanisms of n‐butanol formation in butyl acrylate latexes

The mechanisms involved in the formation of n‐butanol during the synthesis of butyl acrylate containing latices were investigated. The experimental results showed that neither the hydrolysis of butyl acrylate nor of the ester bond in the butyl acrylate segments of the polymer played a major role in the formation of n‐butanol, which was mainly generated from the polymer backbone, by transfer reactions to polymer chain followed by cyclization. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5838–5846, 2007     

The Effects of a Study‐Group Process on the Implementation of Reform in Mathematics Education

In each of three consecutive years, 16 teachers were admitted to a program in which they participated in a study group to reform their teaching practices in mathematics. The 48 (total) elementary school teachers in this program were selected to ensure diversity of setting— urban and suburban, as well as public and parochial. Teachers routinely met with the study group for 1 year, engaging in follow‐up activities after that year. Surveys, interviews, and site visits showed that teachers underwent significant changes in their knowledge, beliefs, and teaching practices and were attempting to implement reform consistent with current standards. Teachers with 11 to 25 years of experience demonstrated the greatest changes. Long‐term effects of the program and its impact on colleagues within the building and district have yet to be studied.     

Activity of TiO2 deposited by the CVD method on ammoxidized surface of a carbonaceous material in hydrogenation of styrene

Hydrogenation of styrene has been applied as a test reaction to study the catalytic activity of TiO₂ deposited by the CVD (chemical vapour deposition) method on the surface of a carbonaceous material enriched in nitrogen (C_N).     

Disintegration and perfectness of measure spaces

For every finite measure space (X,A,P) we find a unique representation P=Q₁+Q₂+Q₃ such that Q₁ is compact, Q₂ is perfect and purely noncompact and Q₃ is purely nonperfect. We show that every Pachl-_O-disintegrable probability space is Ramachandran-_O-disintegrable and therefore perfect and under a certain condition we prove the equivalence between compactness and Ramachandran-_O-disintegrability.     

Solid-phase synthesis of imidazo[4,5-b]pyridin-2-ones and related urea derivatives by cyclative cleavage of a carbamate linkage

A solid-phase synthesis of substituted cyclic urea derivatives as potential heterocyclic library scaffolds is described. 2-Amino-3-nitropyridine is attached to Wang resin via a carbamate linkage. Reduction of the nitro group was achieved with SnCl(2).2H(2)O. Reductive alkylation with a range of substituted benzaldehydes followed by cyclative cleavage afforded a small library of 3-substituted imidazo[4,5-b]pyridine-2-ones in 33-45% yield and 59-88% purity. Subsequently, this methodology was applied to the synthesis of 3-substituted imidazo[4,5-f]quinolin-2-ones.     

Amperometric biosensor for the rapid determination of salicylate in whole blood

A method for the determination of salicylate in whole blood is described. The assay uses salicylate hydroxylase to convert salicylate to catechol in the presence of NADH and molecular oxygen. The formation of catechol is monitored amperometrically by oxidation at +300 mV vs.Ag/AgCl and the size of the oxidation current is related to the concentration of salicylate in the sample. The reagents are incorporated into the working electrode of a disposable strip, allowing measurements to be made on a drop of blood within 1 min. The functional range of the assay can be extended to the equivalent of 7.2 mM plasma salicylate by incorporating benzoate as a component of the reaction system. The method has the advantages of simplicity and speed compared with standard procedures, and should prove especially useful in suspected overdose situations.     

Zur Kenntnis des Phosphatstoffwechsels der Hefe

Scheinbare Divergenzen zwischen den seinerzeit aufgestellten Phosphatbilanzen in Säureextrakten aus phosphatangereicherter und-verarmter Hefe und den in der letzten Mitteilung dieser Reihe erhobenen Befunden über den Gehalt an freien Nucleotiden in demselben Material, veranlaßten eine genauere Überprüfung der Frage, inwieweit die Extraktionsmethoden die Ergebnisse der Nucleotidbestimmung und der Phosphatbilanzen beeinflussen. Es zeigte sich, daß bei Bestimmung der freien Nucleotide, trotz Verwendung verschiedener Extraktionsmittel, sowohl qualitativ als auch quantitativ weitgehend entsprechende Ergebnisse erhalten wurden.Die Resultate können wieder in dem Sinne erklärt werden, daß während der Phosphatanreicherung eine Synthese von Nucleinsäure auf Kosten der freien Nucleotide erfolgt.Gleichzeitig durchgeführte Phosphatbilanzen in den Säureextrakten aus phosphat-verarmter und-angereicherter Hefe ergaben je nach den Extraktionsbedingungen starke, zur Zeit noch schwer deutbare Konzentrationsunterschiede in den einzelnen Phosphatfraktionen.

---

---

Mit 2 Abbildungen     

Disruption of DNA repair processes by carcinogenic metal compounds

Based on pronounced enhancing effects in combination with other DNA-damaging agents the potentials of Ni(II), Cd(II) and As(III) to interfere with DNA repair processes in HeLa cells was investigated. With respect to oxidative DNA damage, Ni(II) and Cd(II) induced DNA strand breaks starting at concentrations of 250 μM and 5 μM, respectively. The induction of oxidative DNA base modifications like 8-hydroxyguanine was restricted to the cytotoxic concentration of 750 μM Ni(II) and not observed after treatment with Cd(II). In contrast, the removal of oxidative DNA base modifications was inhibited at concentrations as low as 50 μM Ni(II) and 0.5 μM Cd(II). Regarding nucleotide excision repair, Ni(II) and Cd(II) disturbed the DNA-protein interactions involved in the damage recognition step when applying HeLa nuclear protein extracts and a UV-damaged oligonucleotide, while As(III) inhibited the actual incision event. In the case of Ni(II) and Cd(II), this effect was reversible by the addition of Mg(II) and Zn(II), respectively. Furthermore, Cd(II) inactivated the isolated bacterial Fpg protein, most likely by the displacement of Zn(II) from its zinc finger structure. Since DNA is continuously damaged by exogenous and endogenous sources, an impaired repair capacity might well account for the carcinogenic action of the metal compounds. Received: 30 July 1997 / Revised: 6 October 1997 / Accepted: 10 October 1997     

Cellulose synthesis in maize: isolation and expression analysis of the cellulose synthase (CesA) gene family

Stalk lodging in maize results in significant yield losses. We have determined that cellulose per unit length of the stalk is the primary determinant of internodal strength. An increase in cellulose concentration in the wall might allow simultaneous improvements in stalk strength and harvest index. Cellulose formation in plants can be perturbed by mutations in the genes involved in cellulose synthesis, post-synthetic cellulose alteration or deposition, N-glycosylation, and some other genes with as yet unknown functions. We have isolated 12 members of the cellulose synthase (CesA) gene family from maize. The genes involved in primary wall formation appear to have duplicated relatively independently in dicots and monocots. The deduced amino acid sequences of three of the maize genes, ZmCesA10–12, cluster with the Arabidopsis CesA sequences that have been shown to be involved in secondary wall formation. Based on their expression patterns across multiple tissues, these three genes appear to be coordinately expressed. The remaining genes show overlapping expression to varying degrees with ZmCesA1, 7, and 8 forming one group, ZmCesA3 and 5 a second group, and ZmCesA2 and 6 exhibiting independent expression of any other gene. This suggests that the varying levels of coexpression may just be incidental except in the case of ZmCesA10–12, which may interact with each other to form a functional enzyme complex. Isolation of the expressed CesA genes from maize and their association with primary or secondary wall formation has made it possible to test their respective roles in cellulose synthesis through mutational genetics or transgenic approaches. This information would be useful in improving stalk strength.