European Space Agency experiments on thermodiffusion of fluid mixtures in space.

This paper describes the European Space Agency (ESA) experiments devoted to study thermodiffusion of fluid mixtures in microgravity environment, where sedimentation and convection do not affect the mass flow induced by the Soret effect. First, the experiments performed on binary mixtures in the IVIDIL and GRADFLEX experiments are described. Then, further experiments on ternary mixtures and complex fluids performed in DCMIX and planned to be performed in the context of the NEUF-DIX project are presented. Finally, multi-component mixtures studied in the SCCO project are detailed.

Diffusion in liquid mixtures.

The understanding of transport and mixing in fluids in the presence and in the absence of external fields and reactions represents a challenging topic of strategic relevance for space exploration. Indeed, mixing and transport of components in a fluid are especially important during long-term space missions where fuels, food and other materials, needed for the sustainability of long space travels, must be processed under microgravity conditions. So far, the processes of transport and mixing have been investigated mainly at the macroscopic and microscopic scale. Their investigation at the mesoscopic scale is becoming increasingly important for the understanding of mass transfer in confined systems, such as porous media, biological systems and microfluidic systems. Microgravity conditions will provide the opportunity to analyze the effect of external fields and reactions on optimizing mixing and transport in the absence of the convective flows induced by buoyancy on Earth. This would be of great practical applicative relevance to handle complex fluids under microgravity conditions for the processing of materials in space.

Optical generation of Voronoi diagram.

We present results of experiments of diffraction by an amplitude screen, made of randomly distributed circular holes. By careful selection of the experimental parameters we obtain an intensity pattern strongly connected to the Voronoi diagram (VD) generated by the centers of the apertures. With the help of simulations we give a description of the observed phenomenon and elucidate the optimal parameters for its observation. Finally, we also suggest how it can be used for a fast, all-optical generation of VDs.

Space intensity correlations in the near field of the scattered light: A direct measurement of the density correlation function g(r)

We show that the two point intensity correlation in the near field of the scattered light is directly related to the two point density correlation g(r). Preliminary measurements on two sets of calibrated random pinholes of 140 and 300 &mgr;m diameters, and on aqueous solutions of latex spheres of 5, 10, and 40 &mgr;m are reported. A discussion on the desirability of the technique as a simple and powerful alternative to low angle scattering will be presented.

Hashimoto's thyroiditis in association with Tolosa Hunt syndrome: a case report.

Tolosa Hunt syndrome (THS) is a painful ophthalmoplegia due to a nonspecific inflammatory process in the cavernous sinus or to parasellar neoplasms. Although the cause of the disease is unknown, previous observations support the hypothesis that THS may be only one manifestation of a generalized vasculitis. The diagnosis is based on findings of painful ophthalmoplegia, excellent response to corticosteroids, and exclusion of other causes including aneurysm, diabetes mellitus, paranasal mucocele, and carotid cavernous fistula. We report the case of a 24-year-old woman with THS who had undergone thyroidectomy 4 years before admission for goiter with histologic diagnosis of Hashimoto's thyroiditis. This case shows the unusual association between Hashimoto's thyroiditis and THS and supports the autoimmune origin of both diseases.

Diffusive mass transfer by nonequilibrium fluctuations: Fick's law revisited.

Recent experimental and theoretical works have shown that giant fluctuations are present during diffusion in liquid systems. We use linearized fluctuating hydrodynamics to calculate the net mass transfer due to these nonequilibrium fluctuations. Remarkably, the mass flow turns out to coincide with the usual Fick's one. The renormalization of the hydrodynamic equations allows us to quantify the gravitational modifications of the diffusion coefficient induced by the gravitational stabilization of long wavelength fluctuations.

A rare case of pancreatic lipoma.

During CT scanning, a pancreatic lipoma was diagnosed in a 70 year-old woman presenting with abdominal pain, elevated amylase and abnormal liver function tests. The patient underwent surgical excision of the lipoma located in the head of the pancreas. The postoperative course was uneventful. This is the third case of pancreatic lipoma described in the literature. It is a very rare neoplasm that should be included in the category of "non-ductal" tumors of the pancreas. The role of different diagnostic tools for the differential diagnosis of ductal pancreatic adenocarcinoma is discussed.

Epithelial ovarian cancer in female pseudohermaphroditism. A diagnosis by computed tomography and review of the literature.

We describe the case of a patient proven to be a female pseudohermaphrodite with a complete virilization syndrome who developed an epithelial tumor of the ovary of borderline malignancy. The tumor appeared as an abdominal mass with cystic features on ultrasonography. The diagnosis of the intersexual condition and adnexal cancer was made by computed tomography (CT).

[Survey on goiter in elementary school children in the Bisagno and Trebbia valleys (Liguro-Emilian Apennines)]. / Inchiesta sul gozzismo in età scolare primaria nelle valli Bisagno e Trebbia (Appennino Ligure-Emiliano).

The authors have made an inquiry about school-children of two villages of Northern Appennines: Bargagli and Ottone, formerly seats of endemic goiter. The disappearance of endemic goiter in the younger generations of these villages, is in accordance with previous observations by one of the writers suggesting that sheep represent an important ecologic factor in endemic areas.

[Effects of a vagolytic substance on the circadian rhythm of the ACTH-secreting system in man]. / Variations circadiennes des effets d'une substance vagolytique sur le système ACTH-secrétant chez l'homme.

The circadian rhythm of plasma cortisol and urinary 17-hydroxy-corticosteroids has been studied in 6 normal volunteers both in basal conditions and after the administration of a single dose of 30 mg of a banthine derivative (the beta methyl-beta-isopropylaminoethyl ester bromide of xantene-9-carbonic acid, "Pervagal") given orally once a day at different hours (midnight, 4 AM, 8 AM, noon, 4 PM, 8 PM). The vagolytic drug inhibits the cortisol secretion only when administered at 4 PM, 8 PM or midnight, whereas it is ineffective when given at different hours. If don't exist circadian variations of the bio-availability of the drug employed, our results suggest that also in human beings as well as in experimental animals, the cholinergic mechanisms are effective, over all if not exclusively, in starting the circadian activation of the hypothalamo-pituitary-adrenal system.

Gradient-driven fluctuations in microgravity.

Equilibrium fluctuations of thermodynamic variables, such as density or concentration, are known to be small and typically occur at a molecular length scale. In contrast, theory predicts that non-equilibrium fluctuations grow very large both in amplitude and spatial size. On earth, the presence of gravity and buoyancy forces severely limits the development of the fluctuations. We will present the results of a 14-year long international collaboration on an experiment on non-equilibrium fluctuations in a single liquid and in a polymer solution under microgravity conditions. Non-equilibrium conditions are generated by applying a temperature gradient across millimetre-size liquid slabs. Phase modulations introduced by fluctuations are measured using a quantitative shadowgraph method, with the optical axis parallel to the temperature gradient. Thousands of images are analysed and their two-dimensional power spectra yield the fluctuation structure function S(q), once data are reduced accounting for the instrumental transfer function T(q). The mean-squared amplitude of the fluctuations exhibits an impressive power-law dependence at larger q and a crossover at low q showing that the fluctuation size is limited by the sample thickness. The shape of the structure function, its increase due to removing gravity, and its dependence on applied gradient are in reasonable agreement with available theoretical predictions.

Capillary-to-Bulk Crossover of Nonequilibrium Fluctuations in the Free Diffusion of a Near-Critical Binary Liquid Mixture.

We have studied the nonequilibrium fluctuations that occur at the interface between two miscible phases of a near-critical binary mixture during a free-diffusion process. The small-angle static scattered intensity is the superposition of nonequilibrium contributions that are due to capillary waves and to bulk fluctuations. A linearized hydrodynamic description of the fluctuations allows us to isolate the two contributions and to determine an effective surface tension for the nonequilibrium interface. As the diffuse-interface thickness increases, we observe the crossover of the contribution from the capillary waves to the bulk fluctuations.

Near-field intensity correlations of scattered light.

We show that the two-point correlation function in the near field of scattered light is simply related to the scattered intensity distribution. We present a new, to our knowledge, optical scheme to measure the correlation function in the near field, and we describe a processing technique that permits the subtraction of stray light on a statistical basis. We present experimental data for solutions of latex spheres, and we show that this novel technique is a powerful alternative to static light scattering.

Equilibrium and nonequilibrium fluctuations at the interface between two fluid phases

We have performed small-angle light-scattering measurements of the static structure factor of a critical binary mixture undergoing diffusive partial remixing. An uncommon scattering geometry integrates the structure factor over the sample thickness, allowing different regions of the concentration profile to be probed simultaneously. Our experiment shows the existence of interface capillary waves throughout the macroscopic evolution to an equilibrium interface, and allows us to derive the time evolution of surface tension. Interfacial properties are shown to attain their equilibrium values quickly compared to the system's macroscopic equilibration time.

Universal behavior of nonequilibrium fluctuations in free diffusion processes

We show that giant nonequilibrium fluctuations are present during the free diffusive remixing occurring in ordinary liquid mixtures and in macromolecular solutions. The static structure factor of the fluctuations is measured by using a quantitative shadowgraph technique. We show that structure factors at different times and from different samples can be rescaled onto a single master curve without any adjustable parameter, thus giving strong evidence that nonequilibrium fluctuations are a universal feature of free diffusion processes.

Circadian periodicity of plasma prolactin in some neurological diseases.

The circadian rhythmicity of plasma PRL has been studied in some neurological diseases in which hypothalamic involvement or abnormalities of brain neurotransmitters has been postulated. 11 patients with Steinert's myotonic dystrophy, 7 with cluster headache and 10 with Huntington's chorea have been studied. By the mean cosinor procedure, a significant circadian rhythm of plasma PRL has been observed both in Steinert's disease and in cluster headache, whereas a circadian periodicity is not detectable in Huntington's chorea, a degenerative disorder affecting the basal ganglia, the hypothalamus and many other areas of the CNS.

Transient oscillations in Soret-driven convection in a colloidal suspension.

We present measurements of the transient stage of Soret-driven convective instability. The sample is a diluted colloidal suspension of silica spheres in water with an unusually large negative Soret coefficient S(T). A large temperature gradient (heating from above) is rapidly applied over the sample, while a shadowgraph imaging technique provides images of the convective flow. From the processing of the variance of the intensity of the images we are able to recover the time evolution of the overall intensity of the convective flow. A typical evolution of such signal exhibits, after a latency time, a peak followed by some damped oscillations leading to a steady-state value. Both the onset time tau(p) (the temporal position of the first peak), and the oscillation period tau(osc) show a power law dependence as a function of the solutal Rayleigh number R(s). The exponents found are compared with predictions from existing models.

Primary Hodgkin's disease of the thyroid: report of a case and a review of the literature.

A case of primary and exclusive Hodgkin's disease of the thyroid gland in a 29-year-old woman and a review of the literature are described. Diagnosis with fine-needle aspiration biopsy (FNAB) was performed before surgery. The patient underwent subtotal thyroidectomy, followed by a radiotherapy dose of 46 Gy. Post-operative histological examination confirmed the cytological diagnosis without evidence of thyroiditis or lymphadenopathy. Five months after thyroidectomy, surgical staging confirmed the exclusive localization of the disease in the thyroid. The patient is followed up on an out-patient basis and is still in good health, 24 months after treatment.