Operating regimes of GaAs-AlGaAs semiconductor ring lasers: experiment and model

Theory and experiments of single-mode ridge waveguide GaAs-AlGaAs semiconductor ring lasers are presented. The lasers are found to operate bidirectionally up to twice the threshold, where unidirectional operation starts. Bidirectional operation reveals that just above threshold, the lasers operate in a regime where the two counterpropagating modes are continuous wave. As the injected current is increased, a new regime appears where the intensities of the two counterpropagating modes undergo alternate sinusoidal oscillations with frequency in the tens of megahertz range. The regime with alternate oscillations was previously observed in ring lasers of the gas and dye type, and it is here reported and investigated in semiconductor ring lasers. A theoretical model based on a mean field approach for the two counterpropagating modes is proposed to study the semiconductor ring laser dynamics. Numerical results are in agreement with the regime sequence experimentally observed when the injected current is increased (i.e., bidirectional continuous-wave, bidirectional with alternate oscillations, unidirectional). The boundaries of the different regimes are studied as a function of the relevant parameters, which turn out to be the pump current and the conservative and dissipative scattering coefficients, responsible for an explicit linear coupling between the two counterpropagating field modes. By a fitting procedure, we obtain good numerical agreement between experiment and theory, and also an estimation for the otherwise unknown scattering parameters.     

Korrosionskennzeichnung von Kupferlegierungen - Polarisationswiderstände in Salzlösungen -

Characterization of the corrosion behaviour of copper alloys – polarisation resistances in salt solutions Experiments with electrolyte copper, Cu with 6% Fe and CuNi90/10 (with Fe or Cr) demonstrate that measured polarisation resistances enable on principle conclusions to be drawn with respect to the probable corrosion behaviour of Cu alloys. This applies in particular to aerated solutions where the negative influence of Cr and the positive influence of Fe can be clearly distinguished. The variation of polarisation resistance with time enables groupes of alloys to be differentiated which initially are characterized by identical kinetic parameters.     

An affordable multispectral imaging system for the digital museum

The use of multispectral imaging for the acquisition of the image content of a digital museum is proposed. The advantages of multispectral imaging over traditional RGB imaging are explained, and the two existing approaches to multispectral acquisition, based on narrowband and wideband sensors respectively, are detailed. The characteristics of wideband multispectral acquisition systems in view of their possible large-scale use for digital museum content acquisition are then discussed, and an example system assembled by the authors and tested in acquisitions of real artifacts is introduced. Finally, it is shown that multispectral representations collected with such systems can be used for several purposes, including reproduction with current and future devices and support for monitoring and restoration, making them a natural choice for master copies in cultural institutions archives.     

Risk factors for cervical presence of human papillomavirus DNA among women at risk for HIV infection. DIANAIDS Collaborative Study Group

Teleost retinas adapted to light show numerous spinules invaginated in the cone pedicles whereas darkness induces a reduction in the number of spinules. Horizontal cells show nematosomes whose size decreases as the number of spinules increases. We have investigated the involvement of actin filaments in spinule formation, by using cytochalasin D through intraocular injection into an eye. The ultrastructural analysis reveals that cytochalasin D impairs spinule formation and nematosome-size reduction in both treated and contralateral untreated retinas.     

Finite element analysis of steady-state nonlinear heat transfer problems

A method of analysis and the associated computer program are presented for the purpose of solving steady-state nonlinear heat transfer problems in two-dimensional structures. The nonlinearity arises from the dependence of the thermal conductivities on temperature as well as from the presence of rediative heat transfer between parts of the structure. The problem is formulated in terms of an integral of conductivity and solved in an iterative way via the finite element concept. Several examples are given to illustrate the validity and practicality of the suggested solution technique.     

Small fiber neuropathy and vasculitis

Vasculitis-associated neuropathy usually presents as multiple mononeuropathies or sensorimotor polyneuropathies that affect large nerve fibers; painful small fiber sensory neuropathy has not previously been described in association with vasculitis. This report describes 2 patients with small fiber neuropathy in whom vasculitis was found to be present. Patients with small fiber neuropathy for which no other cause has been identified should be evaluated for the presence of vasculitis.     

High 1,4-cis-polybutadiene by uranium catalyst. IV. Stretch induced crystallization and ultimate properties

Non-equilibrium tensile properties of high-cis-polybutadiene obtained from an uranium based catalyst are evaluated in comparison with other polybutadienes having lower sterical purity. The conditions for incipient stretch induced crystallization are described. Ultimate properties and strain induced crystallization are found strongly related and their dependence on cis-content is discussed. The higher sterical purity accounts for the best performance of uranium polybutadiene.     

The Association between Single Nucleotide Polymorphisms,including miR-499a Genetic Variants,and Dyslipidemia in Subjects Treated with Pharmacological or Phytochemical Lipid-Lowering Agents

Disorders of lipoprotein metabolism are among the major risk factors for cardiovascular disease (CVD) development. Single nucleotide polymorphisms (SNPs) have been associated with the individual variability in blood lipid profile and response to lipid-lowering treatments. Here, we genotyped 34 selected SNPs located in coding genes related to lipid metabolism, inflammation, coagulation, and a polymorphism in the MIR499 gene—a microRNA previously linked to CVD—to evaluate the association with lipid trait in subjects with moderate dyslipidemia not on lipid-lowering treatment (Treatment-naïve (TN) cohort, n = 125) and in patients treated with statins (STAT cohort, n = 302). We also explored the association between SNPs and the effect of a novel phytochemical lipid-lowering treatment in the TN cohort. We found that 6 SNPs (in the MIR499, TNFA, CETP, SOD2, and VEGFA genes) were associated with lipid traits in the TN cohort, while no association was found with the response to twelve-week phytochemical treatment. In the STAT cohort, nine SNPs (in the MIR499, CETP, CYP2C9, IL6, ABCC2, PON1, IL10, and VEGFA genes) were associated with lipid traits, three of which were in common with the TN cohort. Interestingly, in both cohorts, the presence of the rs3746444 MIR499 SNP was associated with a more favorable blood lipid profile. Our findings could add information to better understand the individual genetic variability in maintaining a low atherogenic lipid profile and the response to different lipid-lowering therapies.