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81.
P. Moskal H.-H. Adam A. Budzanowski R. Czyzykiewicz D. Grzonka M. Janusz L. Jarczyk B. Kamys A. Khoukaz K. Kilian P. Kowina T. Lister W. Oelert T. Rozek R. Santo G. Schepers T. Sefzick M. Siemaszko J. Smyrski S. Steltenkamp A. Strzalkowski P. Winter M. Wolke P. Wüstner W. Zipper 《The European Physical Journal A - Hadrons and Nuclei》2003,18(2-3):335-338
The production of
- and
-mesons in elementary nucleon-nucleon collisions has been investigated at the synchrotrons CELSIUS, COSY and SATURNE. The high-quality proton beam with low emittance and small momentum spread permits to study the creation of these mesons very close to the kinematical threshold, where --due to the rapid growth of the phase space volume-- the total cross-section increases by orders of magnitude over a few MeV range of the excess energy. The magnitude and energy dependence of the total cross-section as well as the occupation distribution of the phase space serve as observables for investigating the mechanisms underlying the production processes and the interaction of mesons with nucleons. The precise data on the
and
creation via the
reactions allowed to settle the general features of the
- and
-meson production and revealed the sensitivity of the mentioned observables to the nucleon-nucleon-meson final-state interaction. The particular production properties, like for example, the determination of the dominating exchange processes which lead to the excitation of the S
11 nucleon isobar in the case of
creation, must be established by confrontation with other observables. The present status of this investigation with an emphasis on the results of the COSY-11 Collaboration is briefly presented. The available data are interpreted in view of the production mechanism and the meson-nucleon interaction.Received: 30 September 2002, Published online: 22 October 2003PACS:
13.60.Le Meson production - 13.75.-n Hadron-induced low- and intermediate-energy reactions and scattering (energy
GeV) - 13.85.Lg Total cross sections - 25.40.-h Nucleon-induced reactions 相似文献
82.
83.
The utility of triple-quantum (TQ)-filtered (23)Na NMR spectroscopy for discriminating between intra- and extracellular Na(+)(Na(i)(+) and Na(e)(+), respectively) in a solid tumor in vivo was evaluated using TmDOTP(5-) as a (23)Na shift reagent. Infusion of 80 mM TmDOTP(5-) without added Ca(2+) produced baseline-resolved Na(i)(+) and Na(e)(+) peaks in both single-quantum (SQ) and TQ-filtered (23)Na spectra. The Na(i)(+) signal represented 22+/-4% of the SQ spectrum, but 59+/-10% of the TQ-filtered spectrum. Therefore, the Na(i)(+) contribution in TQ-filtered spectra is much higher than in SQ spectra. Both SQ and TQ-filtered Na(i)(+) signals increased by about 75% 1 h after sacrificing the animal. The TQ-filtered relaxation times did not change during this time, indicating that changes observed in TQ-filtered spectra collected with a preparation time of 3 ms represent changes in the concentration of sodium ions contributing to the TQ-filtered signal. Similar experiments were conducted without TmDOTP(5-) to determine changes in the Na(e)(+) signal in the absence of the shift reagent. The changes in total SQ and TQ-filtered signals 1 h after sacrificing the animal showed that the SQ Na(e)(+) signal decreased by approximately 35%, while the TQ-filtered Na(e)(+) signal did not change significantly. This demonstrates that the TQ-filtered (23)Na signal is relatively insensitive to changes in Na(e)(+) content. To our knowledge, this work represents the first evaluation of multiple-quantum-filtered (23)Na spectroscopy to discriminate between intra- and extracellular Na(+) in a solid tumor in vivo. 相似文献
84.
Charles A. Kingsbury Jon Weinhold Jeremy Winter 《Journal of Physical Organic Chemistry》2007,20(3):161-166
Three reactions were studied in the diastereomers of 1‐(benzenesulfonyl)‐2‐nitro‐1‐phenylpropane ( 1A and 1B ) and briefly in related compounds: elimination of the benzenesulfonyl group, epimerization of one diastereomer to the other, and deuterium/hydrogen exchange at the methine group next to nitro in starting material. The two diastereomers showed quite different reactivity. The high melting diasteromer showed rapid elimination and some exchange. The low melting diastereomer (at approximately a half‐life) showed extensive epimerization, and elimination to the alkene, but little exchange. There is little effect of aromatic substituents on reaction course. The situation is complicated by re‐addition of benzenesulfinate to the alkene. The addition reaction was similar to elimination in agreement with the Principle of Microscopic Reversibility expectations. An electron transfer mechanism for addition is calculated to be comparatively favorable. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
85.
M. Blennow T. Ohlsson W. Winter 《The European Physical Journal C - Particles and Fields》2007,49(4):1023-1039
We investigate non-standard Hamiltonian effects on neutrino oscillations, which are effective additional contributions to
the vacuum or matter Hamiltonian. Since these effects can enter in either the flavor or mass basis, we develop an understanding
of the difference between these bases representing the underlying theoretical model. In particular, the simplest of these
effects are classified as “pure” flavor or mass effects, where the appearance of such a “pure” effect can be quite plausible
as a leading non-standard contribution from theoretical models. Compared to earlier studies investigating particular effects,
we aim for a top–down classification of a possible “new physics” signature at future long-baseline neutrino oscillation precision
experiments. We develop a general framework for such effects with two neutrino flavors and discuss the extension to three
neutrino flavors, and we demonstrate the challenges for a neutrino factory to distinguish the theoretical origin of these
effects with a numerical example as well. We find how the precision measurements of neutrino oscillation parameters can be
altered by non-standard effects alone (not including non-standard interactions in the creation and detection processes) and
that the non-standard effects on Hamiltonian level can be distinguished from other non-standard effects (such as neutrino
decoherence and decay) if we consider the specific imprint of the effects on the energy spectra of several different oscillation
channels at a neutrino factory. 相似文献
86.
The phase transition during chemical lithium insertion into α-MoO3 was investigated by chemical analysis, X-ray diffraction (XRD) and electrochemical characterisation. The samples have been
prepared by reaction of various amounts of water-free lithium iodide with fine-particulate orthorhombic molybdenum trioxide
in n-hexane (non-aqueous media), which yielded materials with different Li/Mo ratio. XRD investigations of these materials proved
that the crystal structure of the layered α-MoO3 has been changed after the chemical lithiation. The phase transition ranged from 0.25 < x < 0.5 in Li
x
MoO3 upon chemical lithium insertion into α-MoO3. The XRD lines of lithium inserted phase Li
x
MoO3 grew at the expense of the XRD lines of the pristine α-MoO3 as lithium ions were chemically inserted until the disappearance of lines related to α-MoO3. The electrochemical performance of the lithiated samples is improved in comparison with the starting material (non-lithiated
α-MoO3). 相似文献
87.
Detection of the DeltaF508 mutation in the CFTR gene by means of time-resolved fluorescence methods.
S Kirschstein S Winter D Turner G L?ber 《Bioelectrochemistry and bioenergetics (Lausanne, Switzerland)》1999,48(2):415-421
A rapid recognition in the base sequence of nucleic acids is an important prerequisite toward the diagnosis of genetic diseases and their carrier states. We have developed a hybridisation method in which a fluorescently labeled oligonucleotide is used to detect point mutations in a target by a simple fluorescence lifetime analysis of the emission of the fluorescent label. We applied this method to detect the deltaF508 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene in a model system and with biologically derived PCR product and discuss the potential generality of this method. 相似文献
88.
89.
J. Dorenbosch F. Udo J. V. Allaby U. Amaldi G. Barbiellini M. Baubillier F. Bergsma A. Capone W. Flegel F. Grancagnolo M. Jonker L. Lanceri M. Metcalf C. Nieuwenhuis J. Panman R. Plunkett C. Santoni K. Winter I. Abt F. W. Büsser H. Daumann P. D. Gall T. Hebbeker F. Niebergall P. Stähelin P. Gorbunov E. Grigoriev V. Kaftanov V. Khovansky A. Rosanov A. Baroncelli L. Barone B. Borgia C. Bosio M. Diemoz U. Dore F. Ferroni E. Longo L. Luminari P. Monacelli S. Morganti F. de Notaristefani L. Tortora V. Valente CHARM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1989,41(4):567-589
A determination of sin2 θ w based on measurements of elastic scattering of muon-neutrinos and muon-anti-neutrinos on atomic electrons is described. These purely leptonic processes were studied using the CHARM calorimeter exposed to neutrino and antineutrino wide-band beams at the CERN super proton synchrotron. A total of 83±16 neutrino-electron and 112±21 antineutrino-electron events have been detected. From the measurement of the ratio of muon-neutrino and muon-antineutrino cross-sections a value of sin2 θ w =0.211±0.037 was obtained. 相似文献
90.