2-Phenoxypropene as Protective Reagent of Chiral Alcohols

2-Phenoxypropene (2) was applied as a novel protective reagent of chiral alcohols, yielding 2-phenoxy-isopropyl (PIP) ethers. Introduction and cleavage of the protective group was achieved under mild conditions.     

Single-shot readout of electron spins in a semiconductor quantum dot

We report on a method for single-shot readout of spin states in a semiconductor quantum dot that is robust against charge noise and can be used even when the electron temperature exceeds the energy splitting between the states. The spin states are first correlated to different charge states using a spin dependence of the tunnel rates. A subsequent fast measurement of the charge on the dot then reveals the original spin state. The method is analyzed theoretically, and compared to a previously used method. We experimentally demonstrate the method by performing readout of the two-electron spin states, achieving a single-shot visibility of more than 80%. We find very long triplet-to-singlet relaxation times (up to several milliseconds), with a strong dependence on in-plane magnetic field.     

REBUILDING THE EASTERN BALTIC COD STOCK UNDER ENVIRONMENTAL CHANGE–A PRELIMINARY APPROACH USING STOCK,ENVIRONMENTAL, AND MANAGEMENT CONSTRAINTS

ABSTRACT. . The population dynamics of the Eastern Baltic cod (Gadus morhua callarias L.), unlike many other stocks, shows a strong dependency on environmental conditions. To test the implications of different management policies on the stock and the fishery in a system of global environmental change, we apply a spatially disaggregated, discrete time, age‐structured model of the Eastern Baltic cod stock in 50 year simulation analyses. The simulation provides an analysis of stock, yield, and revenue development under various management policies and environmental scenarios. The policy analysis, focusing on different regulations of fishing mortality, is embedded into three environmental scenarios, assuming low, medium, or high climate and environmental change. The environmental assumptions are based on simulation results from a coupled atmosphere‐ocean regional climate model, which project salinity in the Baltic Sea to decrease by 7–47% in the period 2071–2100 relative to the reference period 1961 1990. Our simulation results show that a significant reduction in fishing mortality is necessary for achieving high long‐term economic yields. Moreover, under the environmental scenarios presented, a stock collapse cannot be prevented. It can, however, be postponed by the establishment of a marine reserve in ICES subdivision 25.     

Error Probabilities for Bounded Distance Decoding

Decoding errors can be seen from the point of view of the receiver or the transmitter. This naturally leads to different functions for the decoding error probability. We study their behaviour and the relation between these two functions. Though both functions are equally good when used to compare two codes with respect to decoding errors only one of them reflects in general the properties such a function should have. This is not the function one usually considers in the literature when studying decoding errors. Both functions coincide only if the underlying code is perfect. The investigations in this paper can be seen as a continuation of earlier work of MacWilliams (see chap. 16.1 in [2]). J. Lafuente and G. Ochoa are supported by MTM2004-08219-C02-01.     

Projective two-weight codes with small parameters and their corresponding graphs

Projective two-weight codes with relatively small parameters are enumerated up to equivalence. Some properties of codes and related strongly-regular graphs are presented. I. Bouyukliev was partially supported by the Bulgarian National Science Fund under Contract MM1304/2003. J.Winne thanks the Fund for Scientific Research—Flanders (Belgium) for a Research grant.     

The bidirectional mode expansion method for two-dimensional waveguides: the TM case

The mode expansion propagation method is a modelling technique for a large variety of waveguide components. Until now only the case with TE modes has been reported; we give details on the mode expansion propagation method for TM modes. Instead of one type of overlap integral in the TE case, a TM analysis requires two kinds of overlap integrals. The inclusion of radiation modes in this method is discussed. The modifications in the algorithm to include waveguides with gain or loss structures are also considered.As an example, the method was used for analysing a grating-assisted codirectional coupler. In particular, the radiation loss is calculated and compared with calculations when TE modes, instead of TM modes, propagate through the codirectional coupler. The radiation losses are found to be much higher for TM modes.     

Durch Tempern erzeugte Veränderung der Kettenanordnung in verstreckten Polyamiden: Nachweis durch Richtungswechsel von orientierten Aufwachsungen (Epitaxie)

Zusammenfassung Die bekannte Veränderung der Kettenanordnung die man durch Tempern von verstrecktem 6-Polyamid und 66-Polyamid erhält, entspricht einem Richtungswechsel der Längsachse der nadelförmigen Kristalle von Pentachlorphenol bei der orientierten Aufwachsung (Epitaxie) auf diesen Polyamiden. Orientierungsrichtung ohne Temperung ist die Streckrichtung, bei hinreichend hohem Temperungsgrad die Senkrechte dazu. Senkt man diesen Temperungsgrad, so erhält man beide Orientierungsrichtungen nebeneinander.Diese Epitaxie kann für die Untersuchung von Strukturen solcher Oberflächen herangezogen werden, die andern Methoden nur schwer zugänglich sind wie zum Beispiel Mantelstrukturen von dünnen Fäden und Fasern. Ein charakteristisches Beispiel ist die Epitaxie von Pentachlorphenol auf einem dünnen verstreckten Faden von 6-Polyamid vor und nach dem Tempern.

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Summary The known change in the arrangement of chains obtained by annealing of 6-polyamide and 66-polyamide corresponds to a change of the direction of the long axes of the needle-like crystals of pentachlorophenol at the oriented overgrowth (epitaxy) on the polyamides. The direction of the orientation without annealing is the direction of drawing, at a sufficiently high degree of annealing the perpendicular direction. Lowering this degree of annealing, both directions are obtained side by side.This epitaxy can be applied to the investigation of the structure of surfaces, to which other methods are only accessible with difficulty for example the convex surfaces of thin threads and fibers. A characteristic example is the epitaxy of pentachlorophenol on a thin drawn thread of 6-polyamide before and after annealing.

     

Some topological dynamics properties of discrete-time control systems

This paper is concerned with the study of certain stabilityproperties of discrete-time systems by means of topologicalmethods. It turns out that suitably defined sets guarantee thestability of the reachable sets in the vicinity of compact sets.Furthermore, special properties about affine control systemsare given.