39 research outputs found
Studies of contribution of metals bonded with organic matter of seawater to the fluxes of total dissolved metals across water-sediment interface at Vistula Lagoon of Baltic Sea
© 2004 IEEE. Investigations of fluxes of a dissolved element across the water-sediment interface in Vistula Lagoon (Baltic Sea) were carried out in August 2001 and 2002, using chamber experiments. Oxygen, iron(II), total dissolved iron, manganese, copper and lead fluxes were calculated. For the first time the fluxes of metals bonded with organic matter of sea water were studied. The contribution of metals bonded with organic matter to the total flux was varied depending upon conditions and may reach up to 70 %. It was found that metal fluxes at the coastal zone are larger than at the center of the lagoon by the factor of 2-4
Studies of fluxes of dissolved iron and manganese in the Gulf of Finland
© 2004 IEEE. Metal fluxes (total dissolved iron and manganese) across the water-sediment interface were studied in situ in the Gulf of Finland in June 2002 and 2003 using an autonomous benthic lander. Distribution of these metals in the sediment and the porewater was also investigated. Focus was given to understand the behavior of the studied metals at various redox conditions and the influence when sediment resuspension is occurring. Our data indicate the importance of the redox conditions for the iron fluxes with no fluxes at oxic, intermediate at anoxic and high fluxes at suboxic conditions. The fluxes of manganese do not seem to have any correlation with the oxygen levels. Both metals were significantly affected by resuspension, which led to a rapid release
Эффективность химиотерапии и стойкость клинического излечения у впервые выявленных больных деструктивным туберкулезом легких с позиций доказательной медицины
Summary. A randomized multicenter clinical study of chemotherapy efficacy, clinical cure and early recurrence rate involved 240 newly diagnosed patients with cavitary pulmonary tuberculosis treated in municipal and penitentiary medical facilities. Given the primary multiple drug resistance (MDR) of 22.5–33.3 %, intensive chemotherapy with isoniazid, rifampicin, pyrazinamide, ethambutol, kanamycin (or amikacin) and ofloxacin (or lev ofloxacin) allowed to achieve sputum conversion in 100 % of smearpositive patients using sputum microscopy and in 89.2 % using sputum culture, cavity closure in 71.7 %, and clinical cure in 94.2 % with early recurrence rate of 2.6 % in comparison to 54.2, 45.8, 45.8, 65 and 20.5 % respectively in patients treated with isoniazid, rifampicin, pyrazinamide and ethambutol. Lung fibrocavitary lesions with high level of MDR developed in 55 % of patients and were associated with high cost of treatment due to the need in expensive salvage chemotherapy regimens and hightech surgical inter ventions.Резюме. Было проведено рандомизированное многоцентровое клиническое исследование эффективности химиотерапии, клинического излечения и частоты ранних рецидивов у 240 впервые выявленных больных деструктивным туберкулезом легких в гражданских и пенитенциарных противотуберкулезных учреждениях. Доказано, что при уровне первичной множественной лекарственной устойчивости (МЛУ) 22,5–33,3 % режим химиотерапии изониазидом, рифампицином, пиразинамидом, этамбутолом, канамицином (амикацин) и офлоксацином (левофлоксацин) в интенсивной фазе лечения позволяет добиться прекращения бактериовыделения по результатам микроскопии мокроты у 100 % больных и по посеву – у 89,2 %, закрытия каверн – у 71,7 %, клинического излечения – у 94,2 % и ранних рецидивов – у 2,6 % пациентов. В то время как режим химиотерапии изониазидом, рифампицином, пиразинамидом, этамбутолом – у 54,2; 45,8; 45,8; 65 и 20,5 % больных соответственно. При этом в 55 % случаев констатировано формирование фибрознокавернозного туберкулеза с высоким уровнем вторичной МЛУ, что требует больших экономических затрат на дорогостоящие резервные препараты и высокотехнологичные оперативные вмешательства
The Polarization of Radiation in Single Cristals in the Quasiclassical Approach
The radiation emission spectra of polarized photons emitted from charged
particles in single oriented crystals are obtained in Bayer-Katkov
quasiclassical approach. The results of numerical calculations are presented in
the region of small angles of incidence for which the coherent theory fails but
magnetic bremsstrahlung region isn't yet achieved. The spectral distribution of
linear polarization degree repeats, in general, the form of the intensity
distribution. At sufficiently small angles, in the case of planar orientation
of crystal, there is a wide maximum of essential linear polarization at low
frequencies.Comment: Latex with 3 figures (.eps files). used epsfig.sty and wrapfig.st
Ce-doped Li6Ln(BO3)3 (Ln = Y, Gd) Single crystals fibers grown by micro-pulling down method and luminescence properties
Ce3+-doped borate crystal fibers of Li6Gd(BO 3)3 (LGBO) and Li6Y(BO3)3 (LYBO) compositions are grown by the micro-pulling down (μ-PD) method for potential application in developing new neutron detectors. The ternary equilibrium diagram of Li2O-Gd2O3-B 2O3 is drawn and the preparations of homogeneous mixed LGBO and LYBO powders and growth conditions for single crystal fibers are discussed. Absorption, excitation and X-ray luminescence spectra are investigated. Absolute light yield derived from energy spectra and kinetic decay curves measured under α- and γ-scintillations of Ce 3+-doped LGBO and LYBO single crystal fibers is provided. © 2012 Elsevier B.V. All rights reserved
Linear to Circular Polarisation Conversion using Birefringent Properties of Aligned Crystals for Multi-GeV Photons
We present the first experimental results on the use of a thick aligned Si
crystal acting as a quarter wave plate to induce a degree of circular
polarisation in a high energy linearly polarised photon beam. The linearly
polarised photon beam is produced from coherent bremsstrahlung radiation by 178
GeV unpolarised electrons incident on an aligned Si crystal, acting as a
radiator. The linear polarisation of the photon beam is characterised by
measuring the asymmetry in electron-positron pair production in a Ge crystal,
for different crystal orientations. The Ge crystal therefore acts as an
analyser. The birefringence phenomenon, which converts the linear polarisation
to circular polarisation, is observed by letting the linearly polarised photons
beam pass through a thick Si quarter wave plate crystal, and then measuring the
asymmetry in electron-positron pair production again for a selection of
relative angles between the crystallographic planes of the radiator, analyser
and quarter wave plate. The systematics of the difference between the measured
asymmetries with and without the quarter wave plate are predicted by theory to
reveal an evolution in the Stokes parameters from which the appearance of a
circularly polarised component in the photon beam can be demonstrated. The
measured magnitude of the circularly polarised component was consistent with
the theoretical predictions, and therefore is in indication of the existence of
the birefringence effect.Comment: 12 pages, 12 figures, 1 table, REVTeX4 two column, Version for
publicatio
Coherent Pair Production by Photons in the 20-170 GeV Energy Range Incident on Crystals and Birefringence
The cross section for coherent pair production by linearly polarised photons
in the 20-170 GeV energy range was measured for photon aligned incidence on
ultra-high quality diamond and germanium crystals. The theoretical description
of coherent bremsstrahlung and coherent pair production phenomena is an area of
active theoretical debate and development. However, under our experimental
conditions, the theory predicted the combined cross section and polarisation
experimental observables very well indeed. In macroscopic terms, our experiment
measured a birefringence effect in pair production in a crystal. This study of
this effect also constituted a measurement of the energy dependent linear
polarisation of photons produced by coherent bremsstrahlung in aligned
crystals. New technologies for manipulating high energy photon beams can be
realised based on an improved understanding of QED phenomena at these energies.
In particular, this experiment demonstrates an efficient new polarimetry
technique. The pair production measurements were done using two independent
methods simultaneously. The more complex method using a magnet spectrometer
showed that the simpler method using a multiplicity detector was also viable.Comment: 10 pages, 13 figures, 1 table, REVTeX4 two column, Version for
publicatio
Results on the Coherent Interaction of High Energy Electrons and Photons in Oriented Single Crystals
The CERN-NA-59 experiment examined a wide range of electromagnetic processes
for multi-GeV electrons and photons interacting with oriented single crystals.
The various types of crystals and their orientations were used for producing
photon beams and for converting and measuring their polarisation.
The radiation emitted by 178 GeV unpolarised electrons incident on a 1.5 cm
thick Si crystal oriented in the Coherent Bremsstrahlung (CB) and the
String-of-Strings (SOS) modes was used to obtain multi-GeV linearly polarised
photon beams.
A new crystal polarimetry technique was established for measuring the linear
polarisation of the photon beam. The polarimeter is based on the dependence of
the Coherent Pair Production (CPP) cross section in oriented single crystals on
the direction of the photon polarisation with respect to the crystal plane.
Both a 1 mm thick single crystal of Germanium and a 4 mm thick multi-tile set
of synthetic Diamond crystals were used as analyzers of the linear
polarisation.
A birefringence phenomenon, the conversion of the linear polarisation of the
photon beam into circular polarisation, was observed. This was achieved by
letting the linearly polarised photon beam pass through a 10 cm thick Silicon
single crystal that acted as a "quarter wave plate" (QWP) as suggested by N.
Cabibbo et al.Comment: Presented at International workshop "Relativistic Channeling and
Related Coherent Phenomena", Frascati (Rome) 23-26 March 200
Coherent bremsstrahlung, boherent pair production, birefringence and polarimetry in the 20-170 GeV energy range using aligned crystals
The processes of coherent bremsstrahlung (CB) and coherent pair production
(CPP) based on aligned crystal targets have been studied in the energy range
20-170 GeV. The experimental arrangement allowed for measurements of single
photon properties of these phenomena including their polarization dependences.
This is significant as the theoretical description of CB and CPP is an area of
active theoretical debate and development. With the theoretical approach used
in this paper both the measured cross sections and polarization observables are
predicted very well. This indicates a proper understanding of CB and CPP up to
energies of 170 GeV. Birefringence in CPP on aligned crystals is applied to
determine the polarization parameters in our measurements. New technologies for
high energy photon beam optics including phase plates and polarimeters for
linear and circular polarization are demonstrated in this experiment. Coherent
bremsstrahlung for the strings-on-strings (SOS) orientation yields a larger
enhancement for hard photons than CB for the channeling orientations of the
crystal. Our measurements and our calculations indicate low photon
polarizations for the high energy SOS photons.Comment: 23 pages, 27 figures, 2 tables, REVTeX4 two column