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Resumen Objetivo Determinar el valor a-adido de los parametros semicuantitativos en el analisis visual y estudiar los patrones del deposito cerebral de 18F-Florbetaben. Material y metodos Analisis retrospectivo de pacientes con deterioro cognitivo leve o demencia de origen incierto procedentes de un estudio multicentrico. Los PET con 18F-Florbetaben fueron interpretados de forma visual por dos observadores independientes, analizando las regiones “diana” con la finalidad de calcular el acuerdo interobservador. Se realizo analisis semicuantitativo de todas las regiones corticales con respecto a tres regiones de referencia para obtener indices de captacion (SUVRs). Se analizo la capacidad de los SUVRs para predecir el resultado de la interpretacion visual, la posibilidad de deposito preferencial del radiotrazador en algunas regiones “diana” asi como las diferencias interhemisfericas. Resultados Se evaluaron 135 pacientes. En la valoracion visual, 72 estudios se clasificaron como positivos. El acuerdo interobservador fue excelente. Todos los SUVRs fueron significativamente superiores en pacientes con PET positivos con respecto a los negativos. Las regiones corticales correspondientes al area prefrontal y al cingulado posterior mostraron la mejor correlacion con la evaluacion visual, seguidas por la valoracion integrada cortical. Usando analisis de ROC, los SUVRs obtenidos en las mismas regiones “diana” mostraron la mejor capacidad diagnostica. Conclusiones La informacion obtenida de las regiones “diana” parece ser de ayuda en la clasificacion visual, basado en un deposito preferencial de amiloide, lo que permitiria el “machine learning”. El deposito de amiloide, aunque difuso en todas las regiones corticales, parece no ser uniforme ni simetrico.

Resumen Objetivo Determinar la relacion de las medidas de heterogeneidad global y la esfericidad tumoral obtenidas en 18F-FDG PET/TC con variables biologicas, asi como su papel predictivo y pronostico en pacientes con cancer de mama localmente avanzado (CMLA). Material y metodos Se incluyeron 68 pacientes con CMLA, con indicacion de tratamiento neoadyuvante (TNA) y18F-FDG PET/TC basal procedentes de un estudio prospectivo multicentrico en curso. Se determino el perfil inmunohistoquimico [receptores de estrogenos (RE) y de progesterona (RP), expresion del oncogen HER-2, indice de proliferacion Ki-67 y grado histologico tumoral], la respuesta al TNA, la supervivencia global (SG) y la supervivencia libre de enfermedad (SLE). Se realizo la segmentacion tridimensional de las lesiones, obteniendo variables SUV, volumetricas y de heterogeneidad global, asi como la esfericidad. Tambien se analizo la correlacion entre los resultados obtenidos con el perfil inmunohistoquimico, la respuesta a la quimioterapia neoadyuvante (QN) y la supervivencia, tanto global (SG) como libre de enfermedad (SLE). Resultados De las pacientes incluidas, 62 recibieron QN, respondiendo a este solo 18. 13 pacientes recidivaron y 11 fallecieron durante el seguimiento. Los tumores que no expresaron RE tuvieron un COV inferior (p = 0,018), asi como los de Ki-67 alto (p = 0,001) y los de fenotipo de alto riesgo (p = 0,033) frente al resto. Ninguna variable PET mostro asociacion con la respuesta a la QN ni con la SG. La esfericidad y el indice SUVmedio/SUVmax se relacionaron con la SLE de forma inversa (p = 0,041 y p = 0,055, respectivamente) de modo que, por cada decima que aumenta la esfericidad, el riesgo de recurrencia disminuye en un 37%. Conclusiones Los tumores de mama localmente avanzados incluidos en nuestra muestra se comportaron como lesiones homogeneas y esfericas. Los de mayor volumen se asociaron con menor esfericidad. Las variables de heterogeneidad global y la esfericidad no parecen tener un papel predictivo en la respuesta a la QN ni en la SG. Los tumores mas esfericos y con menor variacion en la intensidad de gris entre los voxeles mostraron un menor riesgo de recurrencia.

The mid-infrared (3–22 μm) emissivity of high-purity Ni has been studied in its pure state, during an isothermal oxidation in air at 730 °C and in the fully oxidized state. Measurements in pure Ni were performed in Ar between 200 and 800 °C and a change of slope in the temperature dependence of the total normal emissivity around its Curie temperature (354 °C) was observed. An oxidation process was carried out at 730 °C for 33 days, when the emissivity stopped evolving and the results were representative of NiO. During the first stages, the emissivity evolved forming the usual interference patterns of semi-transparent films. A mixture of oscillatory and monotonic behaviours of the emissivity as a function of wavelength and oxide layer thickness was found, which manifests as a non-trivial evolution of the total normal emissivity, different than that reported in previous studies. Finally, the emissivity of NiO was measured from below its Neel temperature (252 °C) to 850 °C. It showed the typical shape of a ceramic material with an extra vibrational mode due to two-phonon processes and an additional absorption band around 5 μm in the antiferromagnetic phase produced by magnons. The temperature dependence of its total normal emissivity differs significantly from that of a lightly oxidized nickel sample from the literature. Overall, the influence of the surface characteristics on the thermal radiative properties of oxidized Ni is thoroughly discussed and highlights the importance of accounting for all possible sources of infrared emissivity evolution in order to make accurate radiative heat transfer calculations.

The directional spectral emissivities of two V-4Cr-4Ti family alloys, candidate structural materials for fusion first wall/blanket applications, were measured between 200 °C and their working temperatures (700–750 °C), with and without a high-temperature treatment. Besides showing the typical metallic behavior, an increase in the emissivity after the heat treatment (1000–1200 °C) was observed in both alloys. This has been attributed to several microstructural changes, which show the important role of microstructure in the thermal radiative properties of these alloys. In order to explain these mechanisms, the samples were analyzed using electron microscopy and X-ray diffraction. These measurements revealed differences in grain size, composition of the main phase and amount and distribution of dispersed secondary phases. X-ray diffraction and X-ray photoelectron spectroscopy were also used in order to check the extent of oxygen penetration. The results of directional spectral emissivity measurements were integrated to calculate the total hemispherical emissivity, the key heat transfer parameter in the high-temperature high-vacuum environments of fusion reactors. It is observed that the strategy of mechanical alloying with oxide and carbide dispersion to improve the mechanical properties also translates into an enhancement of the radiative refrigerating capability of these alloys.

High-accuracy thermal emission spectroscopy offers certain advantages over other infrared surface spectroscopic techniques. This paper demonstrates the sensitivity and versatility of this method in the study of structural phase transitions. To that end, the Zn-3%Mg-4%Al (mass %) alloy has been used, as it possesses a first-order structural phase transition with a weak calorimetric signal around 270 °C. Both the infrared spectral emissivity and the integrated total emissivity show the typical first order step, whose value has a strong spectral dependence, with the effect continuously decreasing as the wavelength increases until it can no longer be detected beyond 10 μm. Therefore, this means that this transformation is more easily observed through its effect on interband transitions, whose energies typically lie within the near and mid-infrared regions. Some of the advantages of this technique are also discussed in this work and the results are compared to those of temperature-dependent X-ray diffraction and differential scanning calorimetry.

Aim To assess the diagnostic accuracy of 18F-FDG PET/contrast enhanced computed tomography (ceCT) in the detection of asymptomatic recurrences in patients with lymphoma. Material and methods Patients with lymphoma and clinical complete remission underwent 18F-FDG PET/ceCT for standard follow-up.18F-FDG PET and ceCT were evaluated blindly by two independent observers, and classified as positive or negative for recurrence. Additionally a combined evaluation of both techniques was performed. The final diagnosis was established by histopathological analysis or a clinical follow-up longer than 6 months. Statistical diagnostic parameters and concordance levels between both diagnostic techniques were calculated. Results A total of 114 explorations on 90 patients were analyzed. Only 4 patients were diagnosed as asymptomatic recurrence during the follow-up. 18F-FDG PET/ceCT, 18F-FDG PET and ceCT showed an association with the final diagnosis (p = .002 and χ2 = 11.96; p A sensitivity and specificity of 50% and 88% was obtained for the 18F-FDG PET/ceCT civ, 50% and 93% for the 18F-FDG PET, and 50% and 91% for the ceCT. Conclusion The combined use of 18F-FDG PET/ceCT did not offer any advantage compared to any isolated diagnostic technique in the detection of asymptomatic lymphoma recurrence.

espanolObjetivo Valorar la capacidad diagnostica de la 18F-FDG PET/TC con contraste intravenoso (PET/TCciv) en la deteccion de recidivas asintomaticas de pacientes con linfoma. Material y metodos Se realizo una PET/TCciv en pacientes con linfoma para seguimiento estandarizado y en remision completa clinica. Tanto la 18F-FDG PET como la TCciv fueron evaluadas de forma independiente por 2 observadores y clasificadas como positiva o negativa para recurrencia. Adicionalmente se realizo una valoracion combinada de ambas exploraciones. El diagnostico final se establecio por analisis histopatologico o seguimiento clinico superior a 6 meses. Se calcularon los parametros diagnosticos estadisticos y los niveles de concordancia entre ambas tecnicas diagnosticas. Resultados Se analizaron un total de 114 exploraciones pertenecientes a 90 pacientes. Solo 4 pacientes fueron diagnosticados de recurrencia asintomatica durante el seguimiento. La 18F-FDG PET/TCciv, la 18F-FDG PET y la TCciv mostraron asociacion con el diagnostico final (p = 0,002 y χ2 = 11,96; p Se obtuvo una sensibilidad y especificidad del 50 y 88% para la 18F-FDG PET/TCciv, del 50 y 93% para la 18F-FDG PET y del 50 y 91% para la TCciv. Conclusion El uso combinado de la 18F-FDG PET/TCciv no ofrecio ventaja con respecto a ambas tecnicas por separado en la deteccion de recidiva asintomatica por linfoma. EnglishAim To assess the diagnostic accuracy of 18F-FDG PET/contrast enhanced computed tomography (ceCT) in the detection of asymptomatic recurrences in patients with lymphoma. Material and methods Patients with lymphoma and clinical complete remission underwent 18F-FDG PET/ceCT for standard follow-up.18F-FDG PET and ceCT were evaluated blindly by two independent observers, and classified as positive or negative for recurrence. Additionally a combined evaluation of both techniques was performed. The final diagnosis was established by histopathological analysis or a clinical follow-up longer than 6 months. Statistical diagnostic parameters and concordance levels between both diagnostic techniques were calculated. Results A total of 114 explorations on 90 patients were analyzed. Only 4 patients were diagnosed as asymptomatic recurrence during the follow-up. 18F-FDG PET/ceCT, 18F-FDG PET and ceCT showed an association with the final diagnosis (p = 0.002 and χ2 = 11.96; p A sensitivity and specificity of 50% and 88% was obtained for the 18F-FDG PET/ceCT civ, 50% and 93% for the 18F-FDG PET, and 50% and 91% for the ceCT. Conclusion The combined use of 18F-FDG PET/ceCT did not offer any advantage compared to any isolated diagnostic technique in the detection of asymptomatic lymphoma recurrence.

This paper indicates that the sensitivity and accuracy of an infrared radiometer for emissivity measurements depends not only on its design and the measurement method, but also on the spurious radiation. This spurious radiation must be taken into account in the calibration processes since it can be of the same order of magnitude as that of the sample in highly reflective surfaces. Its presence may also be the cause of the inability to detect small surface emissivity changes induced by any surface or bulk properties (anomalous skin effect, phase transitions, etc.). In this paper, the analysis of the spurious radiation is performed for a T-form radiometer and a measurement method where the surroundings are considered to emit as if they were black bodies. However, the results and conclusions that are obtained can be extended without difficulty to any type of radiometer and to all measurement methods. Our research shows that if the sample is placed normal to the emitted radiation optical path, two different spurious radiation sources are detected. However, for low emitting and highly specular materials, they can be eliminated by tilting the sample between 6 and 20° without modifying the spectral emissivity.

The interest on latent heat storage (LHS) materials has experienced a remarkable increase during last years. The main advantage of PCM materials is their higher energy density compared to sensible materials one. In this article the synthesis process and structural and thermophysical characterization of Zn 84 Al 8.7 Mg 7.3, Zn 88.7 Al 11.3 and Zn 92.2 Mg 7.8 (at.%) eutectic metallic alloys have been performed in order to evaluate their potentiality as PCMs for LHS applications. Their correct synthesis process has been proved by the structural study and their melting/solidification temperatures, heat of fusion, specific heat and thermal conductivity have been investigated. The results show melting temperatures of 344 °C, 382 °C and 371 °C and heat of fusion of around 132 J g −1 , 118 J g −1 and 106 J g −1 for Zn 84 Al 8.7 Mg 7.3 , Zn 88.7 Al 11.3 and Zn 92.2 Mg 7.8 , respectively. The obtained energy densities for the investigated alloys are almost two times higher than the ones for similar metallic PCM reported in literature. On the other hand, the measured thermal conductivities are ranging in the solid state from 66 to 139 W m −1 K −1 and in the liquid state, from 33 to 58 W m −1 K −1 , which represent the main advantage of these PCM candidates when are compared to the most studied ones such as the inorganic salts. The proposed storage materials can be a highly suitable solution in TES applications when compact system, high power levels and very fast thermal responses are required.

Efficiency is a critical parameter for a solar cell to be successful and is closely related to the working temperature of the cell. In turn, the temperature can be related to the infrared emissivity, the parameter that governs the thermal radiative properties of a body. In particular, the importance of infrared emissivity in a solar cell is essential in passive cooling applications, where controlled radiative thermal losses could let the cell operate at lower temperatures, the range where they present higher efficiency. In this presentation, the emissivity of c-Si solar cells in the low temperature range (around 50 ºC) is discussed. Traditionally, it has been determined by indirect reflectivity measurements at ambient temperature and extrapolated to working temperatures, but here, a direct measurement is proposed. For an accurate value the measurements are performed in the high accuracy radiometer of the University of the Basque Country, which allows spectral directional emissivity measurements as a function of temperature.

The thermal emissivity spectrum in the mid infrared range (3–21 μ m) as well as its dependence on temperature between 225 and 320 °C has been obtained for the Mg-51%Zn (weight %) eutectic alloy, a candidate for thermal storage. The spectral curves show the typical behaviour of metals and alloys, with emissivity values between 0.05 and 0.2. It was also found that the emissivity spectrum shows variations in each heating cycle during the first few cycles. These changes are associated with the presence of metastable phases in the solid-solid phase transition, present in the alloy below the melting point. The absence of signs of oxidation in air is very favourable for the use of this alloy in thermal energy storage systems. Moreover, the total normal emissivity curves obtained from dynamic spectral measurements have allowed analysing the behaviour phase transition sequence present in this alloy. These experimental results indicate that accurate emissivity measurements can be sensitive enough to account for the structural phase transitions in metals and alloys.

The oxidation kinetics of Ti-6Al-4V samples nitrided in forming gas (N2+5%H2) between 520 and 805 °C is investigated using infrared emissivity measurements. Several kinetic exponents have been observed depending on temperature and time. The activation energy corresponding to the main parabolic rutile growth stage is 223 ± 10 kJ/mol. This value is significantly higher than that corresponding to TiN oxidation, which suggests that it is not the rate-limiting step. The protective role of the nitridation is attributed to the internal Ti2N layer. The microstructural characterization reveals a reduction in the oxygen-diffusion depth compared to non-nitrided Ti-6Al-4V, and a multi-layered Al2O3-TiO2 oxide.

CSP (Concentrated Solar Power) plants technologies use the concentration of solar energy on a receiver to produce heat and then electricity by a thermodynamical process. A solar absorber material is used to convert the energy carried by light into heat. This type of material works at high temperatures (up to 1000 °C) under a highly concentrated solar flux (up to x1000 or more). Optical properties determine the performance of absorbers and it is thus necessary to measure their spectral absorptance and emittance. Solar absorptance is directly linked to the capacity of the absorber material to convert the solar flux into heat. Emittance drives the radiative thermal losses for the heated absorber and depends on the absorber temperature. The characterization of a material in operational conditions at high temperatures requires advanced apparatuses, and different measurement methods exist for the characterization of these two quantities of relevance regarding an absorber. A Round Robin Test (RRT) was conducted with the objective of comparing different new optical apparatuses and methods for measuring the emittance or luminance of various solar absorbers in air. Measurements were carried out directly at temperatures up to 560 °C while heating the samples, and also indirectly by hemispherical reflectance measurements at room temperature. In this paper, the Round Robin Test procedure to compare apparatuses is described, as well as the corresponding reflectance and emittance results on four types of materials. In addition, a discussion of some factors of influence over high temperature measurements in air and of the observed discrepancies among results from the evaluators is presented. The reliability of reflectance/emittance measurements is also demonstrated and statistics of deviations from the mean value are analysed. These allow us to infer information about measurement reproducibility. The reflectance spectra of all samples after high temperature measurements in air (up to 500 °C) do not show any significant changes.

The total hemispherical emissivity of materials used in the solar energy industry is a critical parameter in the calculation of the radiative thermal losses and material efficiency, especially in solar thermal collector absorbing surfaces. This is because the radiative heat losses have a significant economic impact on the final cost of the electricity produced in solar plants. Our laboratory, HAIRL, in the University of the Basque Country (UPV/EHU) in Spain [1] is the first to have published infrared spectral emissivity measurements in Solar Absorber Surfaces (SAS) at working temperature [2]. The laboratory allows measuring between 50 and 1000 ºC in the 0.83-25 μm range and is also capable of doing directional measurements at different angles between 0 and 80 degrees. Therefore, it is suitable for measuring solar selective coatings, for studying high temperature stability and for characterizing thermal energy harvesting materials. In this presentation, we show the specifications of our laboratory, the results of spectral emissivity measurements in air-resistant solar selective coatings and in eutectic alloys for thermal storage and we demonstrate the necessity of measuring at working temperature in order to possess reliable data.

A study on the radiative properties of two pure metals, copper and nickel, using a high accuracy radiometer is carried out. Their spectral emissivity between 3 and 21 lm and its dependence on emission angle and temperature between 250 and 900 C is measured. An evolution of the samples emissivity associated to the surface stress relaxation is observed, which is relieved after two or three heating cycles. Spectral emissivity of metals usually decreases as wavelength increases, but in the case of copper an irregular behaviour has been found. Its spectral emissivity shows a broad plateau around 10 lm, which can be due to the anomalous skin effect. On the other hand, the emissivity usually increases with temperature, but in the case of nickel the emissivity changes little and even slightly decreases for T > 700 C. The experimental directional emissivity of both metals shows the dependence on the emission angle predicted by the electromagnetic theory for metallic samples. By increasing the emission angle, the emissivity dependence on the wavelength strongly decreases. Furthermore, in the case of nickel, an emissivity increase with wavelength is observed for k >2 0lm. The electrical resistivity for both metals is obtained by fitting the experimental emissivity curves with the Hagen–Rubens equation. The results agree fairly well with direct electrical resistivity measurements for copper but show a poor agreement in the case of nickel. 2014 Elsevier Ltd. All rights reserved.

The directional spectral emissivities of four new copper-alloyed spinel coatings for concentrated solar power applications were measured up to 800 °C and compared Pyromark 2500®, deposited in the same conditions on Inconel 625. Reproducible results were found for all coatings at all temperatures, with similar spectral features at working temperatures. The temperature and angular dependences are related to the morphology and composition of the samples. The total hemispherical emissivity increases up to 400 °C for all coatings and then stabilizes, with similar values for most materials, except for the porous Cu0.5Cr1.1Mn1.4O4 coating. This coating offers a reduced total hemispherical emissivity due to increased semitransparency at high angles arising from its porosity. This porosity is linked to an increase in both the solar absorptance and the emissivity in the normal direction due to enhanced light trapping, which means that this coating shows signs of directional selectivity. These results, together with the data dispersion reported for Pyromark, suggest that structural properties are key for the high-temperature emissivity of the coatings and highlight the importance of direct emissivity characterization. Combined with absorptance measurements, these emissivity measurements allow for accurate calculations of the high-temperature efficiencies of the coatings, which reach values up to 0.929.

The eutectic Mg49–Zn51 (mass%) alloy has been identified as a suitable material for latent heat thermal energy storage. Within this scope, the exhibited solid–solid and solid–liquid phase transitions have been carefully characterized. A detailed thermodynamic study focused on the specific heat of the investigated alloy is also provided. The Cp behaviour, very important in the thermal energy storage frame, is theoretically modelled and experimentally validated by quasi-isothermal modulated differential scanning calorimetry measurements. Different intermetallic phases of the Mg–Zn binary system have also been successfully described within this approach in the complete temperature range.

The total emissivity of the absorbing surfaces is a critical parameter in the calculation of the radiative thermal losses in solar thermal collectors. This is because the radiative heat losses have a significant economic impact on the final cost of the electricity produced in a solar thermal plant. This paper demonstrates the need to calculate the total emissivity from spectral emissivity measurements at the working temperature of the solar thermal collector, instead of using extrapolated values from spectral emissivities measured at room temperature. Usual uncertainties produced by the estimation of the total emissivity, in which its temperature dependence is only introduced by the Planck function, are analyzed., This work has been carried out with the financial support of the ETORTEK and SAIOTEK 2013 program (Project numbers S-PC08UN07 and S-PE13UN123 respectively) of the Basque Government in collaboration with CIC-Energigune. T. Echániz acknowledges the Basque Government their support through a Ph.D. fellowship.

A complete experimental study of temperature dependence of the total spectral emissivity has been performed, for the first time, for absorber-reflector selective coatings used in concentrated solar power (CSP) systems for energy harvesting. The coating consist of double cermet layers of silicon oxide with different amounts of molybdenum over a silver infrared mirror layer. The experimental measurements were carried out by a high accurate radiometer (HAIRL) with controlled atmosphere in the mid-infrared and for temperatures between 150 and 600 C. The spectral emissivity is nearly constant in this temperature range. Therefore, the temperature dependence of the total emissivity is given by Planck function. These results were compared with those obtained with the usual calculus using room temperature reflectance spectrum. Finally, the performance of the coating was analyzed by comparison of coated respect to non-coated stainless steel., This work was financially supported by the European Commission (project HITECO FP7-ENERGY-2010-1Collaborative N. 256830) the Spanish Ministry of Science and Innovation (projects FUNCOAT CSD2008-00023, RyC2007-0026) and program ETORTEK of the Consejería de Industria of the Gobierno Vasco in collaboration with the CIC-Energigune Research Center. L. González-Fernández acknowledges the Basque Government the support through a Ph.D. fellowship.

The normal spectral emissivity of a cutting tool based on polycrystalline cubic boron nitride (PCBN) between 400 °C and 1000 °C has been measured. Its shape shows significant differences with respect to that of pure cubic boron nitride (c-BN). Therefore, while the reflectance spectrum of pure c-BN can be fitted to a Lorentz model for linear dielectrics, the reflectance spectrum of the cutting tool (calculated from the emissivity using Kirchhoff's laws) requires a combination of a four-parameter Kurosawa model with a double-damping Drude one. A detailed study of the dependence of the emissivity spectrum with temperature is also performed. The experimental data of this paper is required for accurate temperature measurements with radiation thermometers in machining processes.

When the penetration depth of an electromagnetic wave in a metal is similar to the mean free path of the conduction electrons, the Drude classical theory is no longer satisfied and the skin effect becomes anomalous. Physical parameters of this theory for twelve metals were calculated and analyzed. The theory predicts an emissivity peak epeak at room temperature in the mid-infrared for smooth surface metals that moves towards larger wavelengths as temperature decreases. Furthermore, the theory states that epeak increases with the emission angle but its position, λpeak, is constant. Copper directional emissivity measurements as well as emissivity obtained using optical constants data confirm the predictions of the theory. Considering the relationship between the specularity parameter p and the sample roughness, it is concluded that p is not the simple parameter it is usually assumed to be. Quantitative comparison between experimental data and theoretical predictions shows that the specularity parameter can ...

Spectral directional emissivity has been measured in copper between 3 and 24 μm above room temperature. The experimental spectrum shows a weak broad peak between 7 and 14 μm, which is much more acute for higher emission angles. However, the peak width and position are both independent of the emission angle. The experimental results are in very good agreement with the semiclassical theory of the optical properties of metals in the regime of the anomalous skin effect, in particular with the asymptotic approximation. This comparison suggests that this work shows an optical experimental evidence of the anomalous skin effect.

A study about the influence of the mass and heating rate on the kinetic parameters in solid = solid +gas reactions shows that the low dispersion of the values for activation energy and order parameter support the idea that the use of a small mass is consistent with the theoretical suppositions. This should be taken into account in the diffusion phenomena and temperature gradient involved in the experimental process.

The otoconium genesis was evaluated by morphometric procedures using transmission and scanning electron-microscopic techniques for human fetuses of 50, 110, 134, 173, 210, 220 and 232 mm crown-rump length. Different otoconial crystalline habits were found. For the elongated otoconia (hexagonal prism) different parameters were measured: (1) the mean cleavage angle value of the terminal rhombohedron was 102 (SD 0.65), which was independent of the fetal age; (2) large and short axes show a linear growing law in function of the fetal age, and (3) the otoconial volume grows following a quadratic law. A hypothesis about the physicochemical growth conditions is postulated.