171,334 research outputs found
Annealing Effects On Crystallized Al-doped A-ge:h Thin Films
No full textAnnealing effects on crystallized aluminum doped hydrogenated amorphous germanium (a-Ge:H) thin films have been studied by Raman spectroscopy, as a function of Al concentration ([Al/Ge] ∼10 -6-10 -2 range). All the as-deposited Al-doped a-Ge:H samples with [Al/Ge] < 1.3 at% possess a Raman spectra that includes the signal given by the amorphous phase and a shoulder at around 300 cm -1, that evolves with increasing impurity content, to a well defined peak, corresponding to the contribution of the TO vibration of crystallized Ge. The scattering intensity of samples having 1.4 ≤ [Al/Ge] ≤ ∼ 1.8 at% is dominated by the c-Ge TO vibration. Aluminum concentrations above [Al/Ge] > ∼1.8 at% do not indicate crystallization of a-Ge:H films to levels detectable by Raman spectroscopy. An abrupt crystallization was observed to occur after annealing at T a∼500°C for all the range of the Al-doped samples, including the intrinsic one. These results and the comparison with data of the local order and coordination of Ga atoms into the a-Ge:H network, suggest that Al-induced crystallization originates from fourfold coordinated aluminum atoms that act as crystallization seeds. These seeds have only small influence on the abrupt crystallization of Al doped a-Ge:H films due to annealing treatments. © 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.21037503753Matsuyama, T., Nishikuni, M., Kameda, M., Okamoto, S., Tanaka, M., Tsuda, S., Ohnishi, M., Kuwano, Y., (1990) Mater. Res. Soc. Symp. Proc., 164, p. 329He, S.S., Stephens, M.J., Lucovsky, G., (1993) J. Non. Cryst. Solids, 164, p. 731Oki, F., Ogawa, Y., Fujiki, Y., (1969) Japan J. Appl. Phys., 8, p. 1056Ashtikar, M.S., Sharma, G.L., (1995) J. Appl. Phys., 78, p. 913Haque, M.S., Naseem, H.A., Brown, W.D., (1994) J. Appl. Phys., 75, p. 3928Chambouleyron, I., Fajardo, F., Zanatta, A.R., (2001) Appl. Phys. Lett., 79, p. 3233Chambouleyron, I., Fajardo, F., Zanatta, A.R., (2002) J. Non-cryst. Solids, 299, p. 143Zanatta, A.R., Chambouleyron, I., (2004) J. Appl. Phys., , submitted t
Peron, la Santa Sede y la guerra fria entre "bloque catolico" y "occidente cristiano", 1946-1949
No full textBasandose en la fuerza economica de la Argentina de la posguerra y en la desmedida ambiciòn de su ideologia justicialista, el peronismo intentò entonces reunir y liderar un bloque de naciones catolicas de América y Europa alejado tanto del comunismo ruso que del capitalismo liberal de EE.UU. Para ese fin Peron confiò poder contar con el apoyo moral y politico del Vaticano. Al agravarse la guerra fria, sin embargo, su actitud totalitaria en plano interior y su tendencia a formar un frente che al oponerse a EE.UU. dividia el Occidente en su lucha contra el comunismo, terminò causando un a creciente distancias entre la Argentina de Peròn y la Santa Sede y finalmente el fracaso de la estrategia peronista
Uropatie congenite: stenosi del giunto pielo-ureterale e reflusso vescico-ureterale. Tattica e tecniche chirurgiche
No full textGli Autori analizzano i risultati del trattamento chirurgico nelle uropatie dell'infanzi
Uropatie congenite: stenosi del giunto pielo-ureterale e reflusso vescico-ureterale. Tattica e tecniche chirurgiche
No full textGli Autori analizzano i risultati del trattamento chirurgico nelle uropatie dell'infanzi
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Soil organic matter regulating greenhouse gases in tropical and subtropical environments: a comparison between integrated crop-livestock and annual cropping systems.
No full textCarbon and nitrogen cycles in grassland, annual cropping and integrated crop-livestock (ICL) systems control soil quality and regulate greenhouse gas emissions. The aim of this study was to review the knowledge on driving factors controlling soil organic carbon (OC) accumulation and greenhouse gas emissions in tropical and subtropical Brazilian ecosystems under ICL and annual cropping systems. The ICL system has a significant potential to promote soil OC sequestration, mainly due to biomass addition but also because stabilization by physical protection and organo-mineral associations. The soil OC accumulation in ICL, compared to annual cropping, can extend up to 100 cm depth. In general, emission of nitrous oxide (N2O) from soil is higher in ICL than in annual cropping, although the opposite may also occur. The N2O emission in ICL, however, can be offset by soil OC accumulation, although not always. Strategies to further increase soil OC sequestration and curb N2O emissions must be developed for ICL, which is a system that is being encouraged in Brazil because of the many ecosystem services and economical benefits that it provides
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Soil nitrous oxide fluxes following cover crops management under tillage and no tillage in South Brazil.
No full text- …
