Sensitivity of resonance properties of all-dielectric multilayers driven by statistical fluctuations.

In photonics and emerging fields of quantum and topological materials, increasing demands are placed upon the state and control of electromagnetic fields. Dielectric multilayer materials may be designed and optimized to possess extremely sharp spectral and angular photonic resonances allowing for the creation of fields orders of magnitude larger than the exciting field. With enhancements of 104 and higher, the extreme nature of these resonances places high constraints on the statistical properties of the physical and optical characteristics of the materials. To what extent the spectral and angular shifts occur as a result of fluctuations in the refractive indices and morphologies of the involved low-loss subdomains have not been considered previously. Here, we present how parameter variations such as those caused by fluctuations in deposition rate, yielding bias, random and compensated errors, may affect the resonance properties of low-loss all-dielectric stacks.

Effects of prolonged administration of ultralente insulin on fasting and postbreakfast beta-cell function in normal adults.

Treatment with small doses of subcutaneous insulin is being investigated as a possible approach to prevent type 1 diabetes in humans. The mechanism of prophylactic insulin therapy could involve the inhibition of beta-cell secretory activity and/or the initiation of an active immunoregulatory process. To evaluate the pure metabolic effect of exogenous insulin, the present study assessed whether daily subcutaneous administration of ultralente insulin alters beta-cell function in normal adults. Fourteen healthy adults were randomized to receive 0.2 U/kg x d ultralente insulin (Ultratard; Novo Nordisk, Bagsvaerd, Denmark) or placebo subcutaneously once daily for 30 days. Plasma glucose, C-peptide, and insulin concentrations were measured in the fasting state and 1 hour after a standardized breakfast, during treatment and during a recovery period of 10 days. Insulin administration induced a 15% to 40% decrease of fasting plasma C-peptide. In contrast, postbreakfast plasma C-peptide increased by 40% to 90% in subjects receiving insulin. Fasting and postbreakfast C-peptide concentrations were significantly different between groups during the injection period after adjustment for baseline concentrations (P < .05, ANOVA with repeated measures). These alterations disappeared 3 days after cessation of insulin treatment. The present regimen of exogenous insulin alters endogenous insulin secretion in normal subjects. Instead of the expected beta-cell rest, the effect appeared to be dual, with insulin secretion decreasing in the basal state and increasing after meals.

Comparison of different methods: static and dynamic headspace and solid-phase microextraction for the measurement of interactions between milk proteins and flavor compounds with an application to emulsions.

Interactions between 10 aroma compounds from different chemical classes and 5 mixtures of milk proteins have been studied using static or dynamic headspace gas chromatography and solid-phase microextraction (SPME). Static headspace analysis allows the quantification of the release of only the most abundant compounds. Dynamic headspace analysis does not allow the discrimination of flavor release from the different protein mixtures, probably due to a displacement of headspace equilibrium. By SPME analysis and quantification by GC-MS (SIM mode) all of the volatiles were quantified. This method was optimized to better discriminate aroma release from the different milk protein mixtures and then from oil/water emulsions made with these proteins. The highest difference between the release in different proteins was observed for ethyl hexanoate, which has a great affinity for beta-lactoglobulin. Ethyl hexanoate is thus less released from models and emulsions containing this protein.