Cyclopolymerisation. 2. Mitt. ESR-Untersuchungen der Reaktionen freier Radikale einiger Diolefine

Ohne Zusammenfassung     

Small-angle muon and bottom-quark production in p&pmacr; collisions at radicals = 1.8 TeV

This Letter describes a measurement of the muon cross section originating from b-quark decay in the forward rapidity range 2.4<| y(&mgr;)|<3.2 in p&pmacr; collisions at sqrt[s] = 1.8 TeV. The data used in this analysis were collected by the D0 experiment at the Fermilab Tevatron. We find that next-to-leading-order QCD calculations underestimate b-quark production by a factor of 4 in the forward rapidity region.     

Liquid chromatographic determination of total and beta-N-oxalyl-L-alpha,beta-diaminopropionic acid in lathyrus sativus seeds using both refractive index and bioelectrochemical detection

The development of a stability-indicating assay for ranitidine hydrochloride using a mobile phase added ion-interaction reagent was achieved. The assay easily separated all known and unknown impurities/degradants. This assay may be used for the determination of purity, identity and strength for the active ingredient and finished dosage forms. Placebo samples were analyzed for all of the dosage forms and did not interfere with the separation. The system was found to be linear over a range of 0.056 to 44.4 microg/g, with a limit of detection of 0.028 microg/g and a limit of quantitation of 0.056 microg/g. The system precision was determined to be 0.7%. The development of the stability-indicating assay and the effect that each chromatographic variable had on the separation will be discussed.     

Experiencing the space we share: rethinking subjectivity and objectivity

Mathematics in schools exists substantially as pedagogical material crafted for supposed modes of apprehension. But of course such apprehension depends on how we understand mathematical objects and how we understand human subjects. The apprehension of mathematical objects is examined through sessions with student teachers researching their own spatial awareness from a pedagogical point of view. The paper is guided by the recent work of Alain Badiou whose philosophical model develops a Lacanian conception of human subjectivity and defines a new conception of objectivity. In this model the conception of subjectivity comprises a refusal to allow humans to settle on certain self-images that have fuelled psychology and set the ways in which humans are seen as apprehending the mathematically defined world. The assertion of an object, meanwhile, is associated with finding a place for it in a given supposed world, and it may reconfigure that world. The composite model understands learning as shared participation in renewal where there is a mutual dependency between the growth of human subjects and of mathematical objects. Renewal is referenced to a diversity of ever shifting discursive parameters that enable learning through negotiating the spaces within which we operate and the objects those spaces allow. Learning to teach then comprises developing sensitivity towards the discursive spaces that allow others to build objects. The paper provides examples from teacher education activities centred in addressing these concerns.     

Monomer Sequencing in Living Anionic Polymerization Using Kinetic Control

Alternating copolymers containing diphenylethylene (DPE) or diphenylethylene derivatives were prepared by living anionic polymerization using kinetic control. Due to steric hindrance DPE cannot homopolymerize. Therefore alternating copolymers can be prepared by ensuring the rate of cross-propagation (k₁₂) of the co-monomer is favoured over the rate of self-propagation (k₁₁). This reactivity ratio (r₁ = k₁₁/k₁₂) can be controlled by many different factors, such as choice of monomer, electron-donating or withdrawing substituents on DPE, choice of solvent, etc. We report our progress on preparing alternating copolymers by varying these factors.     

On the computability-theoretic complexity of trivial, strongly minimal models

We show the existence of a trivial, strongly minimal (and thus uncountably categorical) theory for which the prime model is computable and each of the other countable models computes . This result shows that the result of Goncharov/Harizanov/Laskowski/Lempp/McCoy (2003) is best possible for trivial strongly minimal theories in terms of computable model theory. We conclude with some remarks about axiomatizability.

     

Remote optical control of an optical flip-flop

We experimentally demonstrate control of a holding-beam-enabled optical flip-flop by means of optical signals that act in a remote fashion. These optical-control signals vary the holding-beam power by means of cross-gain modulation within a remotely located semiconductor optical amplifier (SOA). The power-modulated holding beam then travels through a resonant-type SOA, where flip-flop action occurs as the holding-beam power falls above and below the switching thresholds of the bistable hysteresis. Control is demonstrated using submilliwatt pulses whose wavelengths are not restricted to the vicinity of the holding beam. Benefits of remote control include the potential for controlling multiple flip-flops with a single pair of optical signals and for realizing all-optical control of any holding-beam-enabled flip-flop.