1,721,030 research outputs found
Critical behavior of thermal diffusivity and thermal conductivity of Cr2O3 at the Néel transition
No full textThe photopyroelectric technique has been used to study the critical behavior of thermal diffusivity and thermal conductivity of Cr2O3 at the antiferromagnetic-paramagnetic phase transition. Deviation from the conventional Van Hove theory has been observed and the results have been explained in terms of a uniaxial model (n=1) with energy conservation and a nonconserved order parameter. A sharp dip, due to critical slowing down, is present in the thermal diffusivity while the thermal conductivity shows no anomaly in the critical region. A power-law fit with a background contribution and a term to correct for the thermal-diffusivity anomaly gives a critical exponent b=-0.09±0.02 and a critical amplitude ratio of U+/U-=0.51. © 1994 The American Physical Society
Simultaneous characterization of optical turbidity, specific heat and latent eat of liquid crystals nanocolloids
No full textOn the selection of the experimental parameters in a Thermal-Wave-Resonator-Cavity (TWRC) configuration
No full textPhotopyroelectric study of specific heat, thermal conductivity, and thermal diffusivity of Cr2O3 at the Néel transition
No full textA photopyroelectric technique has been used to simultaneously measure the critical behavior of specific heat, thermal conductivity, and thermal diffusivity of Cr2O3 at the antiferromagnetic-paramagnetic phase transition. An Ising-like behavior has been found for max≤3×10-3 with α=0.10±0.02 and A/A'=0.48±0.03. A possible crossover between Ising and Heisenberg behaviors has been found if is increased. Thermal diffusivity data have been fitted according to the model for a uniaxial antiferromagnet with energy conservation for ≤3×10-3 with a critical exponent b=-0.11±0.02. A correction term similar to the static correction to scaling factor has been introduced in the fitting function. No anomaly has been found in thermal conductivity. © 1994 The American Physical Society
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Simultaneous characterization of optical and thermal parameters of liquid-crystal nanocolloids with high-temperature resolution
No full textWe report on the high-temperature resolution measurements of the optical and thermal parameters of a liquid-crystal-silica nanoparticle colloid, as well as its video inspection, simultaneously performed in an upgraded photopyroelectric calorimeter. Over the nematic-isotropic coexistence region, the determined nematic correlation length, obtained from turbidity measurements, showed the characteristic two-step nematic nucleation process previously reported only for the specific heat
Photopyroelectric study of the thermal parameters of antiferromagnets at the Neel temperature
No full textHigh resolution measurements have been performed with the photopyroelectric technique to study the static and dynamic critical behaviour of the thermal parameters of the two antiferromagnets Cr2O3 and FeF2 close to the Neel temperature. Specific heat, thermal diffusivity and thermal conductivity behaviours have been simultaneously measured in the critical region of the second order antiferromagnetic-paramagnetic phase transition. Critical exponents and the critical amplitude ratios of specific heat and thermal diffusivity have been determined. We have also studied single crystal Chromium for which the antiferromagnetic - paramagnetic phase transition is first order. The effect of thermal annealing on the signal amplitude and phase in the vicinity of the transition has been reported
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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