University of Warsaw

About: University of Warsaw is a education organization based out in Warsaw, Poland. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 20832 authors who have published 56617 publications receiving 1185084 citations. The organization is also known as: Uniwersytet Warszawski & Warsaw University.

Testing quantum nonlocality in phase space

Abstract: We propose an experiment demonstrating the nonlocality of a quantum singlet-like state generated from a single photon incident on a beam splitter Each of the two spatially separated apparatuses in the setup performs a strongly unbalanced homodyning, employing a single photon counting detector We show that the correlation functions violating the Bell inequalities in the proposed experiment are given by the joint two-mode Q-function and the Wigner function of the optical singlet-like state This establishes a direct relationship between two intriguing aspects of quantum mechanics: the nonlocality of entangled states and the noncommutativity of quantum observables, which underlies the nonclassical structure of phase space quasidistribution functions

Structure and Spectra of Three-Dimensional ( H 2 O ) n Clusters, n = 8 , 9 , 10

Abstract: The vibrational OH stretch spectra have been measured for size-selected pure water clusters $({\mathrm{H}}_{2}\mathrm{O}{)}_{n}$, in the size range $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}8--10$. Comparison between experiment and calculations suggests that the spectra originate from a small number of ``microcrystalline'' structures, based on the cubic octamer. The $n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}8$ spectra are caused by two isomers of ${D}_{2d}$ and ${S}_{4}$ symmetry. The proposed lowest energy nonamer and decamer structures are derived from the octamer by insertion of one and two two-coordinated molecules, respectively, into the cube edges.

Acidity of Hydroxyl Groups: An Overlooked Influence on Antiradical Properties of Flavonoids

Abstract: The reactions of 10 flavonoids with 2,2-diphenyl-1-picrylhydrazyl radical (dpph(*)) carried out in alcohols always occur significantly faster than in acidified alcohols or in dioxane. These fast kinetics benefit from the contribution of the electron transfer from a flavonoid anion to a radical, a mechanism known as Sequential Proton-Loss Electron-Transfer (SPLET), which adds to the kinetics of single-step Hydrogen Atom Transfer (HAT)/Proton Coupled Electron Transfer (PCET) processes (see Acc. Chem. Res. 2007, 40 , 222.). The domination of SPLET over HAT/PCET in case of a flavonoid reacting with electron-deficient radicals such as peroxyls or dpph(*) in polar solvents explains the enhancement of antioxidant activity of 3-hydroxyflavone. It also elucidates the great acceleration in the reactions of dpph(*) with quercetin, morin, galangin, and 7,8-dihydroxyflavone. The analysis of structure-acidity and structure-activity relationships for 10 flavonoids clearly indicates that hydroxyl group at position 7 is the most acidic site. Thus, in polar solvents this group can participate in radical reaction via SPLET. In nonpolar solvents the most active site in quercetin (a flavonoid antioxidant commonly found in plants) is 3',4'-dihydroxyl moiety and HAT/PCET occurs. However, in ionization-supporting solvents an anion formed at position 7 is responsible for very fast kinetics of quercetin/dpph(*) reaction because both mechanisms participate: HAT (from catechol moiety in ring B) and SPLET (from ionized 7-hydroxyl in ring A). Because of conjugation of rings A, B, and C the final structure of the formed quercetin radical (or quercetin anion radical) is the same for the SPLET and HAT/PCET mechanisms.

Electron- and muon-neutrino content of the atmospheric flux.

Abstract: Neutrino interactions from a 7.7 kton yr exposure of the IMB-3 detector are analyzed. A total of 935 contained events radiating over {similar to}50 MeV of {hacek C}erenkov-equivalent energy and consistent with atmospheric neutrino interactions are identified. Of these, 610 have a single {hacek C}erenkov ring. Single-ring interactions are efficiently separated into those containing a showering particle (produced mainly by {nu}{sub {ital e}}) and those containing a nonshowering particle (produced mainly by {nu}{sub {mu}}). In the momentum range 100{lt}{ital p}{sub {ital e}}{lt}1500 MeV/{ital c} and 300{lt}{ital p}{sub {mu}}{lt}1500 MeV/{ital c}, the fraction of nonshowering events is 0.36{plus minus}0.02(stat){plus minus}0.02(syst). Based on detailed models of neutrino production and interaction, a fraction of 0.51{plus minus}0.01(stat){plus minus}0.05(syst) is expected. This deficit of nonshowering, or excess of showering, events relative to the total is supported by an independent analysis of muon decay signals. In the same sample 33{plus minus}2(stat)% of events are accompanied by one or more muon decays, while 43{plus minus}1(stat)% are expected. Further studies that could reduce systematic errors and discover the cause of these discrepancies are suggested.