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We analyze the multi-time correlations of a laser-induced Bose Einstein condensate. We use quantum stochastic methods to obtain under certain circumstances a Fokker-Planck equation which describes the phase-difussion process, and obtain an analytical expression of the two-time correlations. We perform also quantum Monte Carlo numerical simulations of the correlations, which are in good agreement with the predicted analytical results.
We consider entanglement-assisted remote quantum state manipulation of bipartite mixed states. Several aspects are addressed: we present a class of mixed states of rank two that can be transformed into another class of mixed states under entanglement-assisted local operations with classical communication, but for which such a transformation is impossible without assistance. Furthermore, we demonstrate enhancement of the efficiency of purification protocols with the help of entanglement-assisted operations. Finally, transformations from one mixed state to mixed target states which are sufficiently close to the source state are contrasted with similar transformations in the pure-state case.
We compute the shift of the critical temperature Tc with respect to the ideal case for a weakly interacting uniform Bose gas. We work in the framework of the canonical ensemble, extending the criterion of condensation provided by the canonical particle counting statistics for the zero-momentum state of the uniform ideal gas. The perturbative solution of the crossover equation to lowest order in power of the scattering length yields (Tc - Tc0)/Tc0=-0,93ap 1/3, where Tc0 is the transition temperature of the corresponding ideal Bose gas , a is the scattering length, and p is the particle number density. This is at vaiance with the standard grand canonical prediction of a null shift of the critical temperature in the lowest perturbative order. The non-equevalence of statistical ensemble for the ideal Bose gas is thus confirm (at the lowestperturbative level) also in the presence of interactions.
Region - Nation - Europa
(2000)
Diffuse reflectance measurements and photon migration studies with near infrared (NIR) diode lasers were employed to elucidate experimental methods for determining absorption and scattering coefficients and species concentrations in highly scattering solutions. Applicability of theoretical approaches were established by investigating model systems with absorbing (e.g. ink, malachite green) and scattering (e.g. milk powder, caolinit) species in aqueous solution. While diffuse reflectance measurements practically requires calibration procedures, photon migration studies allow quantitative determination of absorption and scattering coefficients of turbid solutions consistent with absorptions coefficients obtained from Lambert-Beer's law. Furthermore, NIR absorption spectra of water, chlorinated hydrocarbons (chloroform, 1,2-dichloroethane, trichloroethene) and of various sugars ($alpha$-D-glucose, sucrose, maltose) are discussed. Spectral variations of NIR water absorption with temperature and solvents are exammined. Exemplary, NIR diode laser detection of water in acetone/water mixtures is performed.
Self-assembly, ordered nanostructures and functionality of polyelectrolyte-amphiphile complexes
(2000)
Die früheren Hochkulturen
(2000)
Trauer in Hegels Ästhetik
(2000)
Deformationsmodelle nach Auswertung von Tiltmeter- und GPS-Daten für den Vulkan Merapi (Indonesien)
(2000)
An algal culture medium was developed which reflects the extreme chemical conditions of acidic mining lakes (pH 2.7, high concentrations of iron and sulfate) and remains stable without addition of organic carbon sources. It enables controlled experiments e.g. on the heterotrophic potential of pigmented flagellates in the laboratory. Various plankton organisms isolated from acidic lakes were successfully cultivated in this medium. The growth rates of an Chlamydomonas- isolate from acidic mining lakes were assessed by measuring cell densities under pure autotrophic and heterotrophic conditions (with glucose as organic C-source) and showed values of 0.74 and 0.40, respectively.
Adverbs and Adjunction
(2000)
The papers collected in this volume were all presented at the workshop on Adverbs and Adjunction, held at the University of Tromsoe, in April 17-18, 1999. The presentations by Kristin M. Eide &Inghild Flaate, Henriette de Swart, Artemis Alexiadou and Adam Wyner could not be included here.
The articles deal with the syntax, semantics and morpbology of adverbs and their interaction with other syntactic phenomena. A number of tbe contributions is concerned with an evaluation of the hypothesis that adverbs are specifiers of functional heads, which are universally ordered. Specifically, Adger &Tsoulas argue that locative adverbials are licensed by an aspectual head that encodes telicity, while manner adverbials are licensed by a light verb that encodes agentivity, both being situated low in the VP structure. According to the authors, the prime function of these heads is to license aspects of the featural composition of the object, and the licensing of these low adverbials is a by-product of the way that the EPP features of these heads functions. Costa presents data from European Portuguese in support of the traditional analysis of adverbs as adjuncts. Ernst shows that manner, measure, and domain adverbs, and more generally, adverbs and other adjuncts such as participant PPs and adjunct secondary predicates (depictives), are not rigidly ordered. Hence the paper supports theories where linear order is largely a function of the interaction of compositional rules for the various adjuncts, plus their lexico-semantic requirements.
For Haider, adverbials are adjoined or embedded, depending on the relation to the head of the containing phrase: they are adjoined if they precede the head of the containing phrase. They are embedded if they follow the head of tbe containing phrase. But the relative order of adverbials is a reflex of an interface condition. Moreover, the order pattern of adverbials in the extraposition domain is a function of linear incrementality in a non-compositional subdomain. Laenzlinger, on the other hand, claims that adverbs occupy the A'-specifier of their semantically related functional projection. They are formally licensed via the mechanism of feature checking, which links their distribution to their interpretation. He also considers adverb placement and its interaction with Verb/Argument Movement, fronting and extraposition. The interaction between A-scrambling and adverb placement crosslinguistically is also investigated by Hoffman in a minimalist framework. He claims that adverbs can be pronounced in any set of syntactic positions, but the choice among the various positions is made on non syntactic grounds.
Two papers are concerned with adverbial case. Pereltsvaig examines nominal adverbials marked with Accusative Case, with particular focus on Russian and Finnish. She shows that Accusative adverbials exhibit object-like behavior. She argues that Accusative Case is related to aspectual properties of the VP, and it is thus argued that Structural Accusative Case is checked in [Spec, AspP]. But not all occurrences of morphological accusative case derive from Structural Accusative Case. Thus, the contrasts between Russian and Finnish are explained by the claim that Russian uses accusative case marking for NPs in default objective Case position, whereas Finnish uses partitive in the same position. Manninen shows that in Finnish- adverbs can be analyzed as a sub-category of adjectives and nouns, as they are really case-inflected adjectives and nouns. Manninen proposes that these bear lexical 'adverb' case, i. e. that is they have the form of K(asus;Kase)Ps.
Finally, Vegnaduzzo investigates the polysemy of the ltalian adverb ancora showing that this is only apperent. She argues that all the different readings depend upon the context where it is inserted: each reading is derived by compositionality of ancora basic meaning and the semantic properties of the argument structure of the verb.