107 research outputs found
Resistive Anomalies at Ferromagnetic Transitions Revisited: the case of SrRuO_3
We show that recent resistivity data on SrRuO_3 for T->T_c are consistent
with conventional theory when corrections to scaling are included and a small
shift in T_c is allowed.Comment: 2 pages, 1 figure; revte
Salud y enfermedad desde la perspectiva de los jóvenes. Un estudio en jóvenes escolarizados de la Ciudad de Buenos Aires
Se presentan los datos recogidos a través de la realización de una encuesta a jóvenes escolarizados de la Ciudad de Buenos Aires, acerca de sus conocimientos, actitudes y conductas en relación con la salud. El trabajo forma parte de un estudio más amplio que se enmarca en el Modelo de Escuelas Promotoras de Salud pro-puesto por la Organización
Mundial de la Salud
Critical Phenomena at the Antiferromagnetic Phase Transition of Azurite
We report on high-resolution acoustic, specific-heat and thermal expansion
measurements in the vicinity of the antiferromagnetic phase transition at T_N =
1.88 K on a high-quality single crystal of the natural mineral azurite. A
detailed investigation of the critical contribution to the various quantities
at T_N is presented. The set of critical exponents and amplitude ratios of the
singular contributions above and below the transition indicate that the system
can be reasonably well described by a three-dimensional Heisenberg
antiferromagnet.Comment: 9 pages, 3 figures, proceedings of ICM 2012, JKP
Evidence of exactness of the mean field theory in the nonextensive regime of long-range spin models
The q-state Potts model with long-range interactions that decay as 1/r^alpha
subjected to an uniform magnetic field on d-dimensional lattices is analized
for different values of q in the nonextensive regime (alpha between 0 and d).
We also consider the two dimensional antiferromagnetic Ising model with the
same type of interactions. The mean field solution and Monte Carlo calculations
for the equations of state for these models are compared. We show that, using a
derived scaling which properly describes the nonextensive thermodynamic
behaviour, both types of calculations show an excellent agreement in all the
cases here considered, except for alpha=d. These results allow us to extend to
nonextensive magnetic models a previous conjecture which states that the mean
field theory is exact for the Ising one.Comment: 10 pages, 4 figure
Five-loop additive renormalization in the phi^4 theory and amplitude functions of the minimally renormalized specific heat in three dimensions
We present an analytic five-loop calculation for the additive renormalization
constant A(u,epsilon) and the associated renormalization-group function B(u) of
the specific heat of the O(n) symmetric phi^4 theory within the minimal
subtraction scheme. We show that this calculation does not require new
five-loop integrations but can be performed on the basis of the previous
five-loop calculation of the four-point vertex function combined with an
appropriate identification of symmetry factors of vacuum diagrams. We also
determine the amplitude functions of the specific heat in three dimensions for
n=1,2,3 above T_c and for n=1 below T_c up to five-loop order. Accurate results
are obtained from Borel resummations of B(u) for n=1,2,3 and of the amplitude
functions for n=1. Previous conjectures regarding the smallness of the resummed
higher-order contributions are confirmed. Borel resummed universal amplitude
ratios A^+/A^- and a_c^+/a_c^- are calculated for n=1.Comment: 30 pages REVTeX, 3 PostScript figures, submitted to Phys. Rev.
Use of light scattering in characterizing reactively ion etched profiles
Currently, profile control in plasma etching of submicron structures requires inspection of cleaved samples by scanning electron microscopy. This is time consuming, destructive, and limited to a small subset of processed wafers. We show that light scattering can be used to rapidly characterize submicron differences in reactively ion etched, periodic Si structures. A similar approach has been used previously to monitor etching rates and undercutting using specular and first order diffraction peaks. Here, we measure all orders scattered over 180° as a function of incident angle and polarization and focus on the use of this technique coupled with statistical methodology to distinguish subtle changes in line profile. Although scatter from grating test patterns is examined here, this method should also be applicable to complex, submicron device structures
Final report : SIM comparison in mass standards SIM.M.M-K4
This report summarizes the results of a SIM comparison in masss carried out between 7 NMIs. Five mass standards with nominal values 2 kg, 200 g, 50 g, 1 g and 200 mg have been circulated by the NMIs. The results reported by the participants are consistent with each other and with the key comparison reference valu of the comparison CCM.M-K5 to which the present comparison has been linked.Fil: Becerra, L. O. Centro Nacional de Metrología (CENAM); MéxicoFil: Peña, L. M. Centro Nacional de Metrología (CENAM); MéxicoFil: Luján, L. Centro Nacional de Metrología (CENAM); MéxicoFil: Díaz, J. C. Centro Nacional de Metrología (CENAM); MéxicoFil: Centeno, , L. M. Centro Nacional de Metrología (CENAM); MéxicoFil: Loayza, V. M. Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMetro); BrasilFil: Cacais, F. A. Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMetro); BrasilFil: Ramos, O. Laboratorio Costarricense de Metrología (LaCoMet); Costa RicaFil: Rodriguez, S. Laboratorio Costarricense de Metrología (LaCoMet); Costa RicaFil: Garcia, F. Centro de Estudios, Medición y Certificación de Calidad (CESMEC); ChileFil: Leyton, F. Centro de Estudios, Medición y Certificación de Calidad (CESMEC); ChileFil: Santo, C. Laboratorio Tecnológico del Uruguay (LATU); UruguayFil: Caceres, J. Laboratorio Tecnológico del Uruguay (LATU); UruguayFil: Kornblit, F. Instituto Nacional de Tecnología Industrial (INTI); ArgentinaFil: Leiblich, J. Instituto Nacional de Tecnología Industrial (INTI); ArgentinaFil: Claude, J. National Research Council (NRC); Canad
Final report : SIM comparison in mass standards SIM.M.M-K5
This report summarizes the results of a SIM comparison in masss carried out between 7 NMIs. Five mass standards with nominal values 2 kg, 200 g, 50 g, 1 g and 200 mg have been circulated by the NMIs. The results reported by the participants are consistent with each other and with the key comparison reference valu of the comparison CCM.M-K5 to which the present comparison has been linked.Fil: Becerra, L. O. Centro Nacional de Metrología (CENAM); MéxicoFil: Peña, L. M. Centro Nacional de Metrología (CENAM); MéxicoFil: Luján, L. Centro Nacional de Metrología (CENAM); MéxicoFil: Díaz, J. C. Centro Nacional de Metrología (CENAM); MéxicoFil: Centeno, , L. M. Centro Nacional de Metrología (CENAM); MéxicoFil: Loayza, V. M. Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMetro); BrasilFil: Cacais, F. A. Instituto Nacional de Metrologia, Qualidade e Tecnologia (INMetro); BrasilFil: Ramos, O. Laboratorio Costarricense de Metrología (LaCoMet); Costa RicaFil: Rodriguez, S. Laboratorio Costarricense de Metrología (LaCoMet); Costa RicaFil: Garcia, F. Centro de Estudios, Medición y Certificación de Calidad (CESMEC); ChileFil: Leyton, F. Centro de Estudios, Medición y Certificación de Calidad (CESMEC); ChileFil: Santo, C. Laboratorio Tecnológico del Uruguay (LATU); UruguayFil: Caceres, J. Laboratorio Tecnológico del Uruguay (LATU); UruguayFil: Kornblit, F. Instituto Nacional de Tecnología Industrial (INTI); ArgentinaFil: Leiblich, J. Instituto Nacional de Tecnología Industrial (INTI); ArgentinaFil: Claude, J. National Research Council (NRC); Canad
Tricritical Point and the Doping Dependence of the Order of the Ferromagnetic Phase Transition of La1-xCaxMnO3
We report the doping dependence of the order of the ferromagnetic metal to
paramagnetic insulator phase transition in La1-xCaxMnO3. At x = 0.33,
magnetization and specific heat data show a first order transition, with an
entropy change (2.3 J/molK) accounted for by both volume expansion and the
discontinuity of M ~ 1.7 Bohr magnetons via the Clausius-Clapeyron equation. At
x = 0.4, the data show a continuous transition with tricritical point exponents
alpha = 0.48+/- 0.06, beta = 0.25+/- 0.03, gamma = 1.03+/- 0.05, and delta =
5.0 +/- 0.8. This tricritical point separates first order (x<0.4) from second
order (x>0.4) transitions.Comment: 14 pages, including 4 figures: i.e. 10 pages of text and 4 pages of
figures. to appear in Physical Review Letters (accepted
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