Expectation values of unbounded observables

For an unbounded quantum mechanical observableA, the expectation value A _f and the mean square deviation _f A cannot be denned for all (pure) statesf by A _f = (f,Af) and ( _f A)² = (f,A ² f)-(f,Af)², respectively. More general definitions are given here, which are also valid for state mixtures (density matrices). A general uncertainty relation for unbounded observables is derived.     

Substituted thiazolamide coupled to a redox delivery system: a new gamma-secretase inhibitor with enhanced pharmacokinetic profile

Inhibition of gamma-secretase, one of the enzymes responsible for the cleavage of the amyloid precursor protein (APP) to produce pathogenic A beta peptides, is an attractive approach for the treatment of Alzheimer's disease. We have designed a new gamma-secretase thiazolamide inhibitor bearing a dihydronicotinoyl moiety as Redox Delivery System which allows specific delivery of the drug to the brain. Through, on the one hand, A beta peptide production measurements by specific in vitro assays (gamma-secretase Cell Free assay and Cell Based assay on HEK 293 APP transfected cells) and, on the other hand, pharmacokinetic studies on animal models, the new inhibitor shows a good pharmacokinetic profile as well as a potent gamma-secretase inhibitory activity in vitro. From the obtained results, it is expected that drug will be mainly delivered to the CNS with low diffusion in the peripheral tissues. Consequently the side effects of this gamma-secretase inhibitor on the immune cells could be reduced.     

Omega- and Omega+ production in central Pb + Pb collisions at 40 and 158A GeV

Results are presented on Omega production in central Pb+Pb collisions at 40 and 158A GeV beam energy. For the first time in heavy ion reactions, rapidity distributions and total yields were measured for the sum Omega(-) + Omega(+) at 40A GeV and for Omega(-) and Omega(+) separately at 158A GeV. The yields are strongly underpredicted by the string-hadronic UrQMD model but agree better with predictions from hadron gas models.     

Capillary gas chromatography-mass spectrometry of all 93 acyclic octenes and their identification in fluid catalytic cracked gasoline

The Kováts retention indices of all 93 acyclic octenes on polydimethylsiloxane and squalane as stationary phases as well as their mass spectra were measured. The means of gas chromatography-mass spectrometry (GC-MS) were used for confirmation of GC identification as well as for mass spectrometric deconvolution of the majority of gas chromatographic unseparated isomeric octene peaks. The distinction between corresponding E and Z acyclic octenes, that is either difficult or even impossible by means of GC-MS, was obtained on the basis of larger temperature coefficients of retention indices for Z isomeric octenes than for corresponding E isomers. The retention data expressed as homomorphy factors were correlated with the degree of branching, position of double bond, and position of alkyl group with respect to the double bond of acyclic octenes, and the structure-retention relationships were formulated. The 81 acyclic octenes were identified in FCC gasoline.     

Une Conjecture de Lebesgue

Let A > 0 be an integer. The equation x⁵–y⁵ = Az⁵ wasfirst studied by Dirichlet and Lebesgue. Lebesgue conjecturedin 1843 that if A has no prime divisors of the form 10k+1, theequation has no solutions except the visible ones. Partial resultswere obtained by Lebesgue and by Terjanian in 1987. The purposeof the paper is to prove Lebesgue's conjecture. The main toolused is the method known as the elliptic Chabauty method.     

Discrete entanglement distribution with squeezed light

We show how one can entangle distant atoms by using squeezed light. Entanglement is obtained in steady state, and can be increased by manipulating the atoms locally. We study the effects of imperfections, and show how to scale up the scheme to build a quantum network.     

At-sea measurements of sound penetration into sediments using a buried vertical synthetic array

Acoustic bottom penetration experiments were carried out in a medium-grain sandy bottom at a site in St. Andrews Bay, Florida. These investigations used a new buried, vertical, one-dimensional synthetic array system where a small hydrophone was water-jetted into the sediment to a depth of approximately 2 m. Once buried, this hydrophone was mounted to a vertical robotics stage that translated the hydrophone upward in 1-cm increments. A broadband (3 to 80 kHz) spherical source, positioned 50 cm above the sediment-water interface, was used to insonify the sediment. Measurements were made with insonification angles above and below the critical angle by changing the horizontal distance of the source relative to the insertion point. This new measurement system is detailed, and results are presented that include temporal, frequency, and wavenumber analysis for natural and roughened interfaces. The measured compressional sound speed and attenuation are shown to be self-consistent using the Kramers-Kronig relation. Furthermore, only a single fast compressional wave was observed. There was no observation of a second slower compressional wave as predicted by some applications of the Biot model to unconsolidated water-saturated porous media.     

Synthesis of N-(2-methylpropyl)-2E-undecene-8,10-diynamide, a novel constituent of Echinacea angustifolia

The first synthesis of a diacetylenic amide from Echinacea is reported. The key steps included the reaction of an aldehyde with the monoanion of a diacetylene and the reductive removal of a propargylic alcohol.     

New beta-strand macrocyclic peptidomimetic analogues containing alpha-(O-, S- or NH-)aryl substituted glycine residues: synthesis,chemical and enzymatic properties

In so much as bis-macrocyclic peptidomimetics have been recognized as high affinity substrates for HIV-1 protease, we were interested in the design and synthesis of new bis-macrocyclic bioisosteric analogues whose general structure is displayed on Fig. 2. The structures of these new analogues are characterized by the specific replacement of the methylene of the benzyl group directly attached to the N-acyl glycine residue in the original molecule 1, by its main bioisosteres, i.e. O-, S- and NH-aryl groups. Knowing that an intermediate in which an heteroatomic aryl group is directly linked to a free amine glycine residue is not stable, we developed an original synthetic pathway which involved the coupling of a specific side chain to the exocyclic carboxylic acid function, followed by an elegant oxidation-nucleophilic substitution Steglich-type reaction. Analogues 2a-d were then submitted to chemical and enzymatic hydrolysis. We demonstrated that, as expected, the specific cleavage of the exocyclic N-acyl bond led to the release of aryl moieties (phenol, thiophenol and aniline species). These chemical and enzymatic stability studies brought to light the biological potential of such macrocyclic analogues in infected cells.