A set-valued framework for birth-and-growth process

We propose a set-valued framework for the well-posedness of birth-and-growth process. Our birth-and-growth model is rigorously defined as a suitable combination, involving Minkowski sum and Aumann integral, of two very general set-valued processes representing nucleation and growth respectively. The simplicity of the used geometrical approach leads us to avoid problems arising by an analytical definition of the front growth such as boundary regularities. In this framework, growth is generally anisotropic and, according to a mesoscale point of view, it is not local, i.e. for a fixed time instant, growth is the same at each space point

Le fumarole vulcaniche

Il magma che alimenta i vulcani, oltre ad essere costituito da roccia fusa, è anche ricco di fluidi, tra i quali i più abbondanti sono l’acqua (H2O), l’anidride carbonica (CO2), i composti dello zolfo come l’anidride solforosa (SO2) e l’idrogeno solforato (H2S) ed infine, in concentrazioni minori, anche gli acidi fluoridrico (HF) e cloridrico (HCl)

Classical and fluctuation-induced electromagnetic interactions in micronscale systems: designer bonding, antibonding, and Casimir forces

Whether intentionally introduced to exert control over particles and macroscopic objects, such as for trapping or cooling, or whether arising from the quantum and thermal fluctuations of charges in otherwise neutral bodies, leading to unwanted stiction between nearby mechanical parts, electromagnetic interactions play a fundamental role in many naturally occurring processes and technologies. In this review, we survey recent progress in the understanding and experimental observation of optomechanical and quantum-fluctuation forces. Although both of these effects arise from exchange of electromagnetic momentum, their dramatically different origins, involving either real or virtual photons, lead to different physical manifestations and design principles. Specifically, we describe recent predictions and measurements of attractive and repulsive optomechanical forces, based on the bonding and antibonding interactions of evanescent waves, as well as predictions of modified and even repulsive Casimir forces between nanostructured bodies. Finally, we discuss the potential impact and interplay of these forces in emerging experimental regimes of micromechanical devices.Comment: Review to appear on the topical issue "Quantum and Hybrid Mechanical Systems" in Annalen der Physi

Achieving a Strongly Temperature-Dependent Casimir Effect

We propose a method of achieving large temperature sensitivity in the Casimir force that involves measuring the stable separation between dielectric objects immersed in fluid. We study the Casimir force between slabs and spheres using realistic material models, and find large > 2nm/K variations in their stable separations (hundreds of nanometers) near room temperature. In addition, we analyze the effects of Brownian motion on suspended objects, and show that the average separation is also sensitive to changes in temperature . Finally, this approach also leads to rich qualitative phenomena, such as irreversible transitions, from suspension to stiction, as the temperature is varied

Orientation-dependent Casimir force arising from highly anisotropic crystals: application to Bi2Sr2CaCu2O8+delta

We calculate the Casimir interaction between parallel planar crystals of Au and the anisotropic cuprate superconductor Bi2Sr2CaCu2O8+delta (BSCCO), with BSCCO's optical axis either parallel or perpendicular to the crystal surface, using suitable generalizations of the Lifshitz theory. We find that the strong anisotropy of the BSCCO permittivity gives rise to a difference in the Casimir force between the two orientations of the optical axis, which depends on distance and is of order 10-20% at the experimentally accessible separations 10 to 5000 nm.Comment: 5 pages, 3 figures. Accepted for publication in Physical Review

Nonlinear feedback oscillations in resonant tunneling through double barriers

We analyze the dynamical evolution of the resonant tunneling of an ensemble of electrons through a double barrier in the presence of the self-consistent potential created by the charge accumulation in the well. The intrinsic nonlinearity of the transmission process is shown to lead to oscillations of the stored charge and of the transmitted and reflected fluxes. The dependence on the electrostatic feedback induced by the self-consistent potential and on the energy width of the incident distribution is discussed.Comment: 10 pages, TeX, 5 Postscript figure

UV-selective face cream (Acne RA-1,2) in acne patients: clinical study of effects on epidermal barrier function, sebum production, tolerability and adherence to pharmacological therapy.

BACKGROUND: General skin care recommendations such as the use of moisturisers and products with adequate photoprotection are important components of management for acne patients to complement the medical regimen. This study aimed to evaluate the real-life clinical effects of a novel UV-selective face cream (Acne RA-1,2) on acne, epidermal barrier function, sebum production, adherence and tolerability when used together with pharmacological acne treatment. METHODS: 40 patients receiving pharmacological acne treatment applied Acne RA- 1,2 once-daily for 3 months. Investigator's Global Assessment of acne, trans- epidermal water loss, sebum production and tolerability were assessed after 1 and 3 months. RESULTS: After 3 months, there was a 38% significant clinical improvement in mean Investigator Global Assessment score (3.4 to 2.1), a 29% significant reduction in trans-epidermal water loss (13.2 to 9.4 g/h/m2), and a 17% significant decrease in sebum production vs baseline (234.6 to 195.6 μg/cm2; all p<0.01). 100% of patients reported complete adherence to pharmacological therapy over the summer of the study vs 52.5% in the previous summer. 87.5% considered their acne improved over the summer of the study vs 55.0% in the previous summer. Pruritus, erythema, dryness and total tolerability symptom scores were significantly reduced after 3 months vs baseline (p<0.05). CONCLUSIONS: Acne RA-1,2 is a useful daily adjunct to pharmacological therapy as it helps to mitigate the irritation these therapies cause, increasing adherence to therapy, and leading to a clinical improvement in acne and epidermal barrier function and a decrease in sebum productio

Assessment of the structural representativeness of sample data sets for the mechanical characterization of deep formations.

Accurate characterization of the mechanical behavior of geomaterials at depth is a fundamental need for geologic and engineering purposes. Laboratory tests on samples from well cores provide the material characterization in terms of mechanical response and other relevant properties. Representativeness of a sample data set with respect to the in situ conditions at depth is a key issue, which needs to be addressed to extrapolate the laboratory response to the whole rock mass. We have developed a procedure aimed at quantitatively evaluating the representativeness of laboratory samples. The methodology is based on joint processing of laboratory ultrasonic tests and wellbore sonic logs. A structural index is used to quantify the difference between the average structure of the laboratory sample and the structure of the formation at the wellbore scale. This index could be used to identify different causes of discrepancies between the behavior of the cored samples and the behavior of the rock formation as documented by well logs. Then, it could also be used to integrate laboratory data for the construction of a reliable geomechanical model with reference to the real in situ state. The methodology was applied to three different experimental data sets, showing the effectiveness of the method

Computation and visualization of Casimir forces in arbitrary geometries: non-monotonic lateral forces and failure of proximity-force approximations

We present a method of computing Casimir forces for arbitrary geometries, with any desired accuracy, that can directly exploit the efficiency of standard numerical-electromagnetism techniques. Using the simplest possible finite-difference implementation of this approach, we obtain both agreement with past results for cylinder-plate geometries, and also present results for new geometries. In particular, we examine a piston-like problem involving two dielectric and metallic squares sliding between two metallic walls, in two and three dimensions, respectively, and demonstrate non-additive and non-monotonic changes in the force due to these lateral walls.Comment: Accepted for publication in Physical Review Letters. (Expected publication: Vol. 99 (8) 2007

Wild and traditional barley genomic resources as a tool for abiotic stress tolerance and biotic relations

Barley (Hordeum vulgare L.) is one of the main crops cultivated all over the world. As for other cereals, throughout the centuries barley was subjected by human breeding to genetic erosion phenomena, which guaranteed improved yields in organized (and then mechanized) agriculture; on the other hand, this selection weakened the ability of barley to survive under adverse environments. Currently, it is clear that climate change requires an urgent availability of crop varieties able to grow under stress conditions, namely limited irrigation, salinity, high temperatures, and other stresses. In this context, an important role could be played by wild relatives and landraces selected by farmers, particularly in specific field areas and/or climatic conditions. In this review, we investigated the origin of barley and the potentialities of wild varieties and landraces in different contexts, and their resilience to abiotic stress. The data obtained from Next Generation Sequencing technologies were examined to highlight the critical aspects of barley evolution and the most important features for abiotic stress tolerance. Furthermore, the potential of appropriate mycorrhiza is discussed under the view of the essential role played by these symbioses in field crops. The abilities of specific barley wild varieties and landraces may represent novel opportunities and suggest innovative strategies for the improvement of abiotic tolerance in crops and particularly in barley