Search Results - (Author, Cooperation:C. Krebs)

2018-06-05

Rockefeller University Press

0022-1007

1540-9538

Medicine

Solid Tumors

2011-03-19

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Adenosine/chemistry/metabolism ; Bacterial Proteins/chemistry/genetics/*metabolism ; Biocatalysis ; Carbon/chemistry ; Cysteine/chemistry/metabolism ; Escherichia coli/enzymology ; Escherichia coli Proteins/chemistry/genetics/*metabolism ; Hydrogen/chemistry ; Methylation ; Methyltransferases/chemistry/genetics/*metabolism ; Physicochemical Processes ; RNA, Bacterial/metabolism ; RNA, Ribosomal, 23S/*metabolism ; S-Adenosylmethionine/*metabolism ; Staphylococcus aureus/enzymology

2013-07-23

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Biocatalysis ; Halogenation ; Hydroxylation ; Iron/*chemistry ; Oxidoreductases/*chemistry/metabolism ; Pseudomonas syringae/enzymology

2013-10-12

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Anti-Bacterial Agents/*biosynthesis ; Fosfomycin/*biosynthesis ; Hydrogen Peroxide/chemistry ; Nonheme Iron Proteins/*chemistry/classification ; Oxidoreductases/*chemistry/classification ; Peroxidases/*chemistry/classification ; Yersinia pseudotuberculosis/enzymology

2014-03-08

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Carbapenems/*biosynthesis/*chemistry ; Catalysis ; Crystallography, X-Ray ; Enzymes/*chemistry/genetics ; Escherichia coli ; Hydrogen/chemistry ; Oxidation-Reduction ; Pectobacterium carotovorum/*enzymology ; Stereoisomerism ; Tyrosine/chemistry

2018-03-23

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Geosciences

Computer Science

Medicine

Natural Sciences in General

Physics

Biochemistry

2018-12-11

The American Association of Immunologists (AAI)

0022-1767

1550-6606

Medicine

1532-849X

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

The objectives of the study were: 1) to map the stresses acting on the cement interface of crown and abutment analogs during loading; and 2) to provide a theoretical basis for the hypothesis that resistance to lateral dislodgment is a function of the distribution of compressive force vectors acting on the cement lute.〈section xml:id="abs1-2"〉〈title type="main"〉Materials and MethodsThree-dimensional finite element (FE) meshes of crown and abutment analogs were constructed and loaded in a direction perpendicular to the axes of symmetry of the abutments. Three parameters were investigated: taper (10° and 20° of convergence), abutment substrate (Ni-Cr alloy and dentin), and type of cement (zinc oxide eugenol, zinc phosphate, glass ionomer, and composite resin). The tensile and compressive components of the resulting force systems were plotted along two axes (z: parallel to the axis of symmetry of the crown/abutment complex; and y: perpendicular to z, ie, parallel to the direction of loading). Von Mises stresses were also generated.〈section xml:id="abs1-3"〉〈title type="main"〉ResultsFirst, it was shown that the restoration's axis of rotation was located inside the abutment cone and was perpendicular to and intersected the axis of symmetry of the crown/abutment complex. Second, stress distribution was dependent on the three parameters investigated. Varying taper led to shifts due mainly to alterations in specimen geometry, whereas the abutment substrate and the cement type had a bearing on the level of the axis of rotation. The smaller the modulus of elasticity of the abutment substrate or the cement lute, the farther apical the location of the axis of rotation.〈section xml:id="abs1-4"〉〈title type="main"〉ConclusionsConventional schemes for explaining crown dislodgment in which the restoration rotates around an axis located at the preparation margin should be reassessed. The results of the FE analysis are compatible with the hypothesis that resistance to lateral dislodgment is a function of the distribution of compressive force vectors acting on the cement interface.

Electronic Resource

0009-2614

Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Chemistry and Pharmacology

Physics

Electronic Resource

1432-1939

Springer Online Journal Archives 1860-2000

Biology

Summary If food supply limits density in rodent populations, the addition of supplemental food ought to increase population size. From May to September we added food on 2-hectare areas of white spruce forest in the southern Yukon. In 1977, we used oats with no measurable impact. In 1978 and 1979 we used sunflower seeds and doubled or tripled the population densities of Peromyscus maniculatus and Clethrionomys rutilus. Supplemental feeding with sunflower seeds increased juvenile production in both species, probably by increasing early juvenile survival. The breeding season ended at the same time on experimental and control areas, and the onset of maturity in juveniles was not affected by feeding. Survival of adult rodents was not improved by feeding. Immigration into sunflower seed areas was very high, and was the major factor producing the increase in population density. Body weight was not changed by feeding. Food supply is thus one factor limiting population density in these subarctic small mammals, but we do not know why supplemental food produces no more than a 2- to 3-fold effect on densities.

Electronic Resource

1432-1939

Snowshoe hare ; Predation ; Population cycle

Springer Online Journal Archives 1860-2000

Biology

Summary We relate causes of mortality of snowshoe hares to density of hares over an 8-year period that included a peak in numbers. We then use simulation modeling to examine whether these density-dependent relationships could produce changes in hare density similar to those observed in our study are in Yukon, Canada. Predation during winter was the largest source of mortality for snowshoe hares at Kluane, Yukon during 1978–84. There was a one-year lag in the response of winter predation mortality rate to hare density. There was a two-year lag in the response of winter mortality not caused by predators to hare density. A simple simulation model with density-dependent predation produced 8–11 year cycles only within a narrow range of parameters that are inconsistent with data from the Kluane region. However, a simulation model that predicted winter mortality rates using a delayed density-dependent numerical response and a Type II functional response by predators, produced 8–11 year cycles within the range of parameter values measured in our study. Yet another simulation model that predicted both summer and winter mortality rates using a delayed density-dependent numerical response and a Type II functional response by predators, did not produce 8–11 year cycles within the range of parameter values measured in our study. Lack of data on juvenile mortality may be one reason for this result.

Electronic Resource

1432-1181

Springer Online Journal Archives 1860-2000

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

Zusammenfassung Bei der Verdunstung eines Zweistoffgemisches in ein inertes Trägergas in einer Rieselfilmsäule hängt der Trenneffekt nicht allein von der relativen Flüchtigkeit, sondern auch vom Verhältnis der Diffusionsgeschwindigkeiten beider Stoffe im Trägergas ab. Bei der Verdunstung von Isopropanol-Wasser-Gemischen in trockene Luft zeigte sich, daß das Verhältnis der gasseitigen Stoffübergangskoeffizienten bei großen Gasgeschwindigkeiten etwa gleich der Wurzel aus dem Verhältnis der Diffusionskoeffizienten war. Da der Alkolhol im Trägergas langsamer diffundiert als das Wasser, konnten flüssige Mischungen durch absatzweise Verdunstung mit Alkohol angereichert werden, obwohl der Alkohol leichterflüchtig war. Bei kleinen Gasgeschwindigkeiten lieferte der Gleichstrom immer höhere Stoffübergangskoeffizienten als der Gegenstrom. Beim Gleichstrom wurde der Einfluß des Diffusionskoeffizienten auf den Stoffübergangskoeffizienten mit abnehmender Geschwindigkeit größer, beim Gegenstrom wurde er schwächer.

Abstract The desorption of a binary mixture into a stripping gas flowing through a wetted-wall column is not only governed by the vapour-liquid-equilibrium. Gas-phase diffusivities of the evaporating components have also to be taken into account. Batch wise stripping experiments of Propanol(2)-water-mixtures using dry air as the stripping gas showed, that at high gas rates the mass transfer coefficients were proportional to the square root of the diffusivities. Therefore it was possible to enrich the residual mixture with Propanol(2) because of its lower diffusivity, although Propanol(2) is more volatile. At low gas rates the mass-transfer coefficients were higher for cocurrent flow than for countercurrent flow. Besides at low gas rates the diffusivities had more influence on mass-transfer for cocurrent flow than for countercurrent flow.

Electronic Resource

1435-2451

Enlarged small bowel resection ; Second look operation ; Small bowel obstruction ; Erweiterte Dünndarmresektion ; ≫Second look≪-Operation ; Dunndarmileus

Springer Online Journal Archives 1860-2000

Medicine

Zusammenfassung In 10 Jahren werden 130 Kinder wegen eines Dunndarmileus operiert. In 45 Fallen war die Ursache des Dunndarmileus eine vorausgegangene Laparotomie. Bei 13 dieser 45 Relaparotomien mußte erneut eine Laparotomie durchgeführt werden. In 40 % der Relaparotomiefälle war ein durchblutungsgestörter Darm die Ursache dafür. Funktions- and durchblutungsgestörte, dilatierte, hypertrophierte and atonische Darmanteile, die für die normale Peristaltik ungeeignet sind, sollen durch eine erweiterte Resektion des Dünndarms reseziert werden (Anastomose vitaler Diinndarmabschnitte).

Summary In a 10-year-period, 130 children were operated on for small bowel obstruction. In 45 cases the reason for this obstruction was a previous laparotomy. In 13 of these 45 relaparotomies laparotomy had to be performed again. In 40 % of these cases the blood supply of the bowel was impaired. Dilated, hypertrophied and atonic segments of small bowel should always be resected in order to establish a small bowel anastomosis with viable bowel segments.

Electronic Resource

0021-8383

Chemistry ; Organic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Semiempirische und ab initio Berechnungen zur Tautomerie von Pyrazolin-5-onen in der Gasphase und in LösungEs werden die Ergebnisse einer durchgehend theoretischen Behandlung der Tautomeriegleichgewichte von Pyrazolin-5-onen vorgestellt. Der Formalismus beinhaltet die Berechnung der potentiellen Energie mit Hilfe des MNDO-, STO-3G- und 4-31 G-Verfahrens, die statistisch-thermodynamische Behandlung der Gleichgewichte unter Zugrundelegung des MNDO-Kraftfeldes und die Abschätzung des Lösungsmitteleinflusses mit Hilfe verschiedener klassischer und quantenchemischer Reaktionsfeldmodelle.

3 Tab.

Electronic Resource

0021-8383

Chemistry ; Organic Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Theoretische Beschreibung von Lösungsmitteleffekten. V. Der Mediumeinfluß auf die Lactim-Lactam-Tautomerie von HydroxyazinenDer Lösungsmitteleffekt auf die Tautomeriegleichgewichte der Titelverbindungen wird mit Hilfe klassischer und quantenchemischer Versionen der Solvatonen- und der Reaktionsfeldtheorie berechnet. In Übereinstimmung mit dem Experiment ergeben alle getesteten Verfahren eine Gleichgewichtsverschiebung zugunsten der Lactamform. Zur quantitativen Beschreibung dieses Effektes ist jedoch das Reaktionsfeldmodell besser geeignet.

4 Tab.

Electronic Resource