Supermodularity and subadditivity properties of the entropy on themajorization lattice

We prove that the entropy is a supermodular and subadditive function on the lattice of all n-dimensional probability distributions, ordered according to the partial order relation defined by majorization among vectors     

Characterization of colloidal polymer particles through stability ratio measurements

We propose a general methodology for the estimation of the doublet formation rate constant (proportional to the stability ratio of primary particles) in colloidal dispersions from measurements obtained by common optical techniques, such as dynamic light scattering, static light scattering (nephelometry) or turbidimetry. In contrast to previous approaches relying on the initial slopes of the measured quantities, such as the mean hydrodynamic radius, scattered light intensity or turbidity, we introduce a transformation of the measurables to properly scaled quantities, which grow linearly in time with a slope proportional to the doublet formation rate. Analysis of systematic and random errors allows one to control the error in the estimated value of the aggregation rate. Using this approach, we measured the aggregation rate constant of colloidal polymer particles prepared by surfactant-free emulsion copolymerization of styrene and 2-hydroxyethyl methacrylate (HEMA). It was found that the stability ratio at constant ionic strength decreases with increasing dilution of the original polymer latex. This can be explained by the presence of non-reacted stabilizing species (most likely oxidized HEMA) that desorb from the particle surface upon latex dilution and thus diminish the repulsive interactions between particles. In order to check if the stability of latex particles is influenced by reversibly adsorbed species it is always necessary to perform aggregation experiments at various dilutions.     

Morphology of EVA based nanocomposites under shear and extensional flow

Shear and extensional rheological measurements were conducted in conjunction with laser light scattering (LLS) on ethylene‐vinyl acetate copolymer (EVA) nanocomposites. The materials were prepared by melt‐mixing EVA and commercially acquired layered silicates. Wide Angle X‐Ray Scattering (WAXS) was used to ascertain the degree of layer swelling. This could be attributed to the intercalation of polymer chains into the interlayer of the silicates. The nanocomposites prepared were determined to be predominantly intercalated in nature. In shear rheological tests, the nanocomposites exhibited an increase in viscoelastic properties compared to the pure EVA. The extent of this property enhancement was not as pronounced as had been reported in many instances with respect to other polymer nanocomposites. This could be attributed to the absence of a network structure normally observed in an exfoliated system. The extensional rheological tests showed an increase in extensional flow properties. This was confirmed by the LLS, which indicated that the filled systems had higher deformability than the unfilled one. Polym. Eng. Sci. 44:1220–1230, 2004. © 2004 Society of Plastics Engineers.     

"En-bloc" vertebrectomy in the mobile lumbar spine

BACKGROUND: Primary tumors of the vertebral bodies have previously been treated with total or subtotal excision in a piecemeal fashion (intralesional excision). Radiation therapy has been used to help control tumor growth. Recurrence rates with an intralesional, piecemeal removal of vertebral tumors have been unacceptably high. This study describes a method to excise a lumbar vertebra "en-bloc," and in the process, to perform a marginal (extralesional) resection of a primary tumor of the mobile lumbar spine that allows for a potential surgical cure. METHODS: A combined posterior-anterior procedure allows for an extralesional, marginal resection of the tumor and the involved vertebra. All posterior bony elements, including the pedicles and the adjacent intervertebral discs, are removed via a posterior approach. An anterior, retroperitoneal approach is then used to remove the vertebral body/tumor as a single specimen. The nerve roots at the involved levels are spared and the spine is instrumented and fused both posteriorly and anteriorly. RESULTS: Three patients successfully had combined posterior-anterior resections of lumbar vertebral chordomas. No permanent neurological complications occurred. Overall morbidity of the procedure was acceptable. At 31-month follow-up, no tumor recurrence has been detected. CONCLUSIONS: "En-bloc" resection of a primary vertebral tumor of the lumbar spine is technically demanding, but potentially curative. The alternative approaches-intralesional excision, radiation therapy, or a combination-are unable to cure these tumors. Long-term, 10-year follow-up will be necessary to confirm whether this en-bloc approach provides a surgical cure.     

Adaptive local learning techniques for multiple-step-ahead wind speed forecasting

A massive deployment of wind energy in power systems is expected in the near future. However, a still open issue is how to integrate wind generators into existing electrical grids by limiting their side effects on network operations and control. In order to attain this objective, accurate short and medium-term wind speed forecasting is required.This paper discusses and compares a physical (white-box) model (namely a limited-area non hydrostatic model developed by the European consortium for small-scale modeling) with a family of local learning techniques (black-box) for short and medium term forecasting. Also, an original model integrating machine learning techniques with physical knowledge modeling (grey-box) is proposed.A set of experiments on real data collected from a set of meteorological sensors located in the south of Italy supports the methodological analysis and assesses the potential of the different forecasting approaches.     

Long term metabolic effects of two dietary methods of treating hyperlipidaemia

OBJECTIVES: To compare the long term metabolic effects of two diets for treating hyperlipidaemia. DESIGN: Randomised controlled study: after three weeks of normal (control) diet, subjects were randomly allocated to one of two test diets and followed up for six months. SETTING: Lipid clinic of tertiary referral centre in Naples. SUBJECTS: 63 subjects with primary type IIa and IIb hyperlipoproteinaemia entered the study, and 44 completed it. Exclusion criteria were taking drugs known to influence lipid metabolism, evidence of cardiovascular disease, homozygous familial hypercholesterolaemia, and body mass index over 30. INTERVENTIONS: Two test diets with reduced saturated fat (8%) and cholesterol (approximately 200 mg/day): one was also low in total fat and rich in carbohydrate and fibre, and the other was low in carbohydrate and fibre and rich in polyunsaturated and monounsaturated fats. MAIN OUTCOME MEASURES: Fasting plasma lipid and lipoprotein concentrations; blood glucose, insulin, and triglyceride concentrations before and after a test meal. RESULTS: In comparison with the control diet, both test diets induced significant and similar decreases in low density lipoprotein cholesterol concentrations (by a mean of 0.72 (SE 0.15) mmol/l, P < 0.001, for low total fat diet; by 0.49 (0.18) mmol/l, P < 0.05, for high unsaturated fat diet) and plasma triglyceride concentrations (by 0.21 (0.09) mmol/l, P < 0.05, for low total fat diet; by 0.39 (0.15) mmol/l, P < 0.05, for high unsaturated fat diet), while high density lipoprotein cholesterol concentrations after fasting and plasma glucose and insulin concentrations during test meals were not modified by either diet. CONCLUSIONS: Both test diets are suitable (alone or in combination) for treatment of hypercholesterolaemia.     

Imaging of the expansion of femtosecond-laser-produced silicon plasma atoms by off-resonant planar laser-induced fluorescence

Planar laser-induced fluorescence measurements were used to investigate the expansion dynamics of a femtosecond laser-induced plasma. Temporally and spatially resolved measurements were performed to monitor the atoms that were ablated from a silicon target. A dye laser (lambda = 288.16 nm) was used to excite fluorescence signals. The radiation of an off-resonant transition (Si 390.55 nm) was observed at different distances from the target surface. This allowed easy detection of the ablated Si atoms without problems caused by scattered laser light. Abel inversion was applied to obtain the radial distribution of the Si atoms. The atom distribution in the plasma shows some peculiarities, depending on the crater depth.     

Imaging multispectral polarimetric sensor: single-pixel design,fabrication, and characterization

A discrete-component approach was taken to establish the operational feasibility of a novel, imaging, midinfrared, multispectral, polarimetric sensor for remote-sensing application. The sensor is designed to exploit the spectral and polarimetric characteristics of the scene as discriminants. Pixelated multispectral filters and polarization filters were designed and fabricated on sapphire and Si substrates, respectively, and both were characterized. A single-pixel spectropolarimetric composite filter was characterized by use of a Fourier transform infrared spectrometer and a Pt-Si thermal-imaging camera. The experimental results show excellent agreement with theoretical predictions.     

Application of femtosecond laser ablation time-of-flight mass spectrometry to in-depth multilayer analysis

A femtosecond laser system was used in combination with a time-of-flight mass spectrometer (TOF-MS) for in-depth profiling of semiconductor and metal samples. The semiconductor sample was a Co-implanted (10(17) ions/cm3) silicon wafer that had been carefully characterized by other established techniques. The total depth of the shallow implanted layer was 150 nm. As a second sample, a thin film metal standard had been used (NIST 2135c). This standard consisted of a silicon wafer with nine alternating Cr and Ni layers, each having a thickness of 56 and 57 nm, respectively. An orthogonal TOF-MS setup was implemented. This configuration was optimized until a sufficient mass resolution of 300 (m/delta m) and sensitivity was achieved. The experiments revealed that femtosecond-laser ablation TOF-MS is capable of resolving the depth profiles of these demanding samples. The poor precision of the measurements is discussed, and it is shown that this is due to pulse-to-pulse stability of the current laser system. Femtosecond-laser ablation TOF-MS is shown to be a promising technique for rapid in-depth profiling with a good lateral resolution of various multilayer thin film samples.