271,156 research outputs found
Ordinary least squares linear regressions of nasal cavity length (ba-pn) against cranial base length (ba-n) and n-ba-pr angle against n-ba-pn angle in chimpanzees and modern humans.
No full textOrdinary least squares linear regressions of nasal cavity length (ba-pn) against cranial base length (ba-n) and n-ba-pr angle against n-ba-pn angle in chimpanzees and modern humans.</p
Growth rate and superconducting properties of Gd-Ba-Cu-O bulk superconductors melt processed in air
No full textA generic Mg-doped Nd-Ba-Cu-O seed crystal has been developed recently for the fabrication of any type of rare earth (RE) based (RE)-Ba-Cu-O single grain bulk superconductor in air. The new generic seed simplifies significantly the top seeded melt growth (TSMG) process for light rare earth based (Nd, Sm, Gd, or mixed rare earth elements) bulk superconductors, in particular. GdBCO single grains have been fabricated successfully in air using the new seed in a cold-seeding process. In this study, precursor powders were enriched with different amounts of BaO2 to investigate the extent of substitution of Gd for Ba in the Gd1+xBa2-xCu3O7-delta solid solution phase. The growth process of large single grains in air was investigated at various growth temperatures under isothermal processing conditions. Crystal growth rate as a function of under-cooling and BaO2 content has been determined from these experiments. The spatial variation of Tc and transition temperature width for applied field aligned along the a/b and c-axis of grains fabricated with different BaO2 content has also been investigated in order to understand the extent of the formation of Gd/Ba solid solution with varying growth temperature and precursor composition. These results have been used to establish the optimum conditions for fabricating solid solution-free, large single grains of GdBCO in air
GONZALEZ, Alberto M. (BA)
No full textGreeting letters from Alberto M. González (BA) to Gen. Alvaro Obregón praising him for his work and expressing his endorsement. / Cartas del Lic. Alberto M. González al Gral. Alvaro Obregón saludándolo, elogiando su labor y manifestándole su adhesión
GONZALEZ, Alberto M. (BA)
No full textGreeting letters from Alberto M. González (BA) to Gen. Alvaro Obregón praising him for his work and expressing his endorsement. / Cartas del Lic. Alberto M. González al Gral. Alvaro Obregón saludándolo, elogiando su labor y manifestándole su adhesión
Seawater nutrient and carbonate ion concentrations recorded as P/Ca, Ba/Ca, and U/Ca in the deep-sea coral D. dianthus
No full textAs paleoceanographic archives, deep sea coral skeletons offer the potential for high temporal resolution and precise absolute dating, but have not been fully investigated for geochemical reconstructions of past ocean conditions. Here we assess the utility of skeletal P/Ca, Ba/Ca and U/Ca in the deep sea coral D. dianthus as proxies of dissolved phosphate (remineralized at shallow depths), dissolved barium (trace element with silicate-type distribution) and carbonate ion concentrations, respectively. Measurements of these proxies in globally distributed D. dianthus specimens show clear dependence on corresponding seawater properties. Linear regression fits of mean coral Element/Ca ratios against seawater properties yield the equations: P/Cacoral (lmol/mol) = (0.6 ± 0.1) P/Casw(lmol/mol) – (23 ± 18), R2 = 0.6, n = 16 and Ba/Cacoral(lmol/mol) = (1.4 ± 0.3) Ba/Casw(lmol/mol) + (0 ± 2), R2 = 0.6, n = 17; no significant relationship is observed between the residuals of each regression and seawater temperature, salinity, pressure, pH or carbonate ion concentrations, suggesting that these variables were not significant secondary dependencies of these proxies. Four D. dianthus specimens growing at locations withOarag 6 0.6 displayed markedly depleted P/Ca compared to the regression based on the remaining samples, a behavior attributed to an undersaturation effect. These corals were excluded from the calibration. Coral U/Ca correlates with seawater carbonate ion: U/Cacoral(lmol/mol) = (?0.016 ± 0.003) ½CO2? 3 ? (lmol/kg) + (3.2 ± 0.3), R2 = 0.6, n = 17. The residuals of the U/Ca calibration are not significantly related to temperature, salinity, or pressure. Scatter about the linear calibration lines is attributed to imperfect spatialtemporal matches between the selected globally distributed specimens and available water column chemical data, and potentially to unresolved additional effects. The uncertainties of these initial proxy calibration regressions predict that dissolved phosphate could be reconstructed to ±0.4 lmol/kg (for 1.3–1.9 lmol/kg phosphate), and dissolved Ba to ±19 nmol/kg (for 41–82 nmol/kg Basw). Carbonate ion concentration derived from U/Ca has an uncertainty of ±31lmol/kg (for 60–120 lmol=kg CO2? 3 ). The effect of microskeletal variability on P/Ca, Ba/Ca, and U/Ca was also assessed, with emphasis on centers of calcification, Fe–Mn phases, and external contaminants. Overall, the results show strong potential for reconstructing aspects of water mass mixing and biogeochemical processes in intermediate and deep waters using fossil deep-sea corals
Nucleation, growth, and zoning phenomena in crystallizing (Ba,Sr)CO3, Ba(SO4,CrO4), (Ba,Sr)SO4, and (Cd,Ca)CO3 solid solutions from aqueous solutions
No full textCrystals of (Ba,Sr)CO3, Ba(SO4,CrO4), (Ba,Sr)SO4, and (Cd,Ca)CO3 solid solutions were obtained by counterdiffusion of reactants through a column of porous silica hydrogel. For each system, a set of experiments, starting with mother solutions of different concentrations, was carried out. The composition of the solids was analyzed by electron microprobe. The method allows the establishment of the influence of the supersaturation on the distribution of material between solid and aqueous phases. With this aim, equilibrium calculations and effective composition of the nucleating crystals are compared.
Two extreme nucleation behaviours have been observed. The solid solutions (Ba,Sr)SO4 and (Cd,Ca) CO3, with endmember solubility products differing by several orders of magnitude, tend to nucleate from aqueous solutions in a bimodal way. In these systems there is a strong preferential partitioning and only a very narrow range of aqueous-phase compositions can coexist in equilibrium with intermediate solid solutions. At high supersaturations, the range of aqueous solutions from which intermediate solid solutions can nucleate expands, but the bimodal effect remains. At the other extreme, the solid solutions with close endmember solubility products, like (Ba,Sr)CO3 and Ba(SO4,CrO4), tend to nucleate in an evenly distributed way. For these solid solutions, a wide range of fluid compositions is in equilibrium with intermediate solid solutions. When nucleation occurs at high supersaturation, the substituting ions incorporate into the nuclei nearly in the same stoichiometric proportion as in the aqueous phase, and the partition coefficients reach values approaching unity.
Finally, the growth process has been studied by monitoring the compositional evolution of the crystals. There is a close relationship between the bimodal trend of a solid solution and the appearance of high gradient compositional zoning. The solid solutions (Ba,Sr)SO4 and (Cd,Ca)CO3 develop sharp compositional zoning when the fluid composition passes through a certain range during the growth process. On the contrary, when the solid solutions (Sr,Ba) CO3 and Ba (SO4, CrO4) grow at high supersaturations, the solids have nearly the same stoichiomerry as the aqueous phase, and the crystals tend to be homogeneous or, at most, to undergo a very gradual compositional evolution.Dirección General de Investigación Científica y Técnica (España)British/Spanish Joint Research ProgrammeDepto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu
Türk resim ve özgün bask sanat nda Basri Erdem
No full textBu ara t rman n konusunu; Türk Resim ve Özgün Bask resim Sanat nda
Basri Erdem olu turmaktad r. Bu amaçla Türk Resim Sanat ve Türkiye de
Bask resim Sanat n n tarihi aktar lm , Basri Erdem in biyografisi, akademisyen
olarak rolü, sanat , sahip oldu u koleksiyonlar, müzecilik yönü anlat lm t r.
Sanatç n n seçilen eserleri plastik de erler ve içerik aç lar ndan analiz edilmi tir.
Bu ara t rma Nitel ara t rma yöntemlerine göre yap lm t r. Çal man n
do as na uygun olarak Kültür Analizi alt deseni tercih edilmi tir. Veriler Doküman
Analizi ve Görü me yöntemi ile elde edilmi tir. Sanatç n n kendisi, çal ma
arkada lar , sanatç lar ile birebir ve yüz yüze yar yap land r lm görü meler
yap lm t r. Sanatç ya ait eserlerin analizi Akademik ve Disiplinleraras Yeni Sanat
Ele tirisi Kuram na göre yap lm , sanat tarihçi Prof. Dr. Tayfun Akkaya n n uzman
görü üne ba vurulmu tur. Toplanan di er veriler Betimsel Analiz ve çerik Analiz
yöntemlerine göre de erlendirilmi tir.
Bu ara t rma, Türk Resim ve Özgün Bask resim Sanat nda büyük önem arz
eden Basri Erdem hakk nda en kapsaml çal ma olmas bak m ndan önemlidir
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