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1.
Phys Rev Lett ; 99(16): 163201, 2007 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-17995248

RESUMEN

We have measured the continuum momentum distribution for radiative electron capture to the continuum (RECC) cusp electrons in 90A MeV U88+ + N2-->U88+ + N2 +* + ecusp(0 degrees ) + hnu (RECC) collisions. We demonstrate that x rays coincident with RECC cusp electrons originate from the short-wavelength limit of the electron-nucleus bremsstrahlung and explain the asymmetric cusp shape by comparison with theory within the relativistic impulse approximation.

2.
Phys Rev Lett ; 97(22): 223202, 2006 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-17155800

RESUMEN

For radiative electron capture into the K shell of bare uranium ions, a study of the polarization properties has been performed. For this purpose a position sensitive germanium detector has been used as an efficient Compton polarimeter. This enabled us to measure the degree of linear polarization by analyzing Compton scattering inside the detector and to determine the orientation of the polarization plane. Depending on the observation angle and the beam energy used, the radiation is found to be linearly polarized by up to 80%. In all cases studied, the plane of polarization coincides with the collision plane. The results will be discussed in the context of rigorous relativistic calculations, showing that relativistic effects tend to lead to a depolarization of the radiation emitted.

3.
Phys Rev Lett ; 94(22): 223001, 2005 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-16090386

RESUMEN

X-ray spectra following radiative recombination of free electrons with bare uranium ions (U92+) were measured at the electron cooler of the ESR storage ring. The most intense lines observed in the spectra can be attributed to the characteristic Lyman ground-state transitions and to the recombination of free electrons into the K shell of the ions. Our experiment was carried out by utilizing the deceleration technique which leads to a considerable reduction of the uncertainties associated with Doppler corrections. This, in combination with the 0 degree observation geometry, allowed us to determine the ground-state Lamb shift in hydrogenlike uranium (U91+) from the observed x-ray lines with an accuracy of 1%. The present result is about 3 times more precise than the most accurate value available up to now and provides the most stringent test of bound-state quantum electrodynamics for one-electron systems in the strong-field regime.

4.
Phys Rev Lett ; 92(20): 203004, 2004 May 21.
Artículo en Inglés | MEDLINE | ID: mdl-15169349

RESUMEN

Radiative recombination transitions into the ground state of cooled bare and hydrogenlike uranium ions were measured at the storage ring ESR. By comparing the corresponding x-ray centroid energies, this technique allows for a direct measurement of the electron-electron contribution to the ionization potential in the heaviest He-like ions. For the two-electron contribution to the ionization potential of He-like uranium we obtain a value of 2248+/-9 eV. This represents the most accurate determination of two-electron effects in the domain of high-Z He-like ions, and the accuracy reaches already the size of the specific two-electron radiative QED corrections.

5.
Phys Rev Lett ; 86(6): 983-6, 2001 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-11177990

RESUMEN

Radiative electron capture, the time-reversed photoionization process occurring in ion-atom collisions, provides presently the only access to photoionization studies for very highly charged ions. By applying the deceleration mode of the ESR storage ring, we studied this process in low-energy collisions of bare uranium ions with low- Z target atoms. This technique allows us to extend the current information about photoionization to much lower energies than those accessible for neutral heavy elements in the direct reaction channel. The results prove that for high- Z systems, higher-order multipole contributions and magnetic corrections persist even at energies close to the threshold.

6.
Phys Rev Lett ; 86(6): 991-4, 2001 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-11177992

RESUMEN

Strong evidence has been found for enhanced multiple electron capture into 46 MeV/u Pb81+ with a significant contribution from the entrance surface of thin carbon foils. Capture of up to five electrons has been observed. The multiple electron capture yield is found to increase with decreasing target thickness for thin targets. A simple model describing the data and showing the importance of capture from surfaces is discussed. Further evidence is found for a pronounced asymmetry between electron capture at the entrance and the exit surfaces. Absolute yields for multiple electron capture and projectile ionization are presented. The experimental total cross sections for single capture and ionization agree well with theory.

7.
Phys Rev Lett ; 84(5): 851-4, 2000 Jan 31.
Artículo en Inglés | MEDLINE | ID: mdl-11017388

RESUMEN

The hyperfine structure (hfs) of electron levels of 23892U ions with the nucleus excited in the low-lying rotational 2(+) state with an energy E(2(+)) = 44.91 keV is investigated. In hydrogenlike uranium, the hfs splitting for the 1s(1/2) ground state of the electron constitutes 1.8 eV. The hyperfine-quenched (hfq) lifetime of the 1s2p 3P0 state has been calculated for heliumlike 23892U and was found to be 2 orders of magnitude smaller than for the ion with the nucleus in the ground state. The possibility of a precise determination of the nuclear g(r) factor for the rotational 2(+) state by measurements of the hfq lifetime is discussed.

10.
Urology ; 39(5): 443-5, 1992 May.
Artículo en Inglés | MEDLINE | ID: mdl-1580035

RESUMEN

A three-year study of infecting organisms in a 600-bed university hospital revealed that despite an overall high incidence of urinary sepsis by resistant organisms only a small portion (3.5%) occurred on the urology service. Possible explanatory causes for this low infection rate included avoidance of cross infection from known pools of resistant organisms, short hospital stays, and close adherence to strictly aseptic techniques in handling patient's tubes and collecting devices. Simple measures provided protection from costly, debilitating disease.


Asunto(s)
Infecciones Bacterianas/microbiología , Infección Hospitalaria/epidemiología , Hospitales de Veteranos/estadística & datos numéricos , Infecciones Urinarias/microbiología , Adulto , Anciano , Infecciones Bacterianas/epidemiología , Infección Hospitalaria/microbiología , Farmacorresistencia Microbiana , Florida/epidemiología , Hospitales con más de 500 Camas , Hospitales Universitarios/estadística & datos numéricos , Humanos , Incidencia , Persona de Mediana Edad , Distribución Aleatoria , Staphylococcus/aislamiento & purificación , Infecciones Urinarias/epidemiología , Urología/estadística & datos numéricos
12.
Phys Rev A ; 43(1): 223-227, 1991 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-9904772
13.
J Am Podiatr Med Assoc ; 80(8): 438-40, 1990 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-2198344

RESUMEN

Hepatitis is a significant disease process for health care professionals. Because of the large number of procedures performed by podiatrists in the course of patient care, they are at particular risk. The variants of hepatitis are reviewed, and the modes of transmission are discussed. Recommendations are made on protective measures to reduce contraction of this disease.


Asunto(s)
Exposición a Riesgos Ambientales , Hepatitis Viral Humana/transmisión , Podiatría , Hepatitis Viral Humana/clasificación , Hepatitis Viral Humana/prevención & control , Humanos
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