Propagation of waves in metallic photonic crystals at low frequencies and some theoretical aspects of left-handed materials

An analytical theory of low frequency electromagnetic waves in metallic photonic crystals with a small volume fraction of a metal is presented. The evidence of the existence of such waves has been found recently via experiments and computations. We have obtained an exact dispersion equation for omega (k) and studied the cutoff frequency omega_0 = omega(0) as a function of parameters of the photonic crystal. An analytical expression for the permittivity epsilon is calculated. It is shown, that if the crystal is embedded into a medium with negative mu, it has no propagating modes at any frequency. Thus, such a compound system is not a left-handed material (LHM). The recent experimental results on the LHM are discussed.Comment: 8 pages, 3 figure

Diffraction theory and focusing of light by left-handed materials

A diffraction theory in a system consisting of left-handed and right-handed materials is proposed. The theory is based upon the Huygens's principle and the Kirchhoff's integral and it is valid if the wavelength is smaller than any relevant length of the system. The theory is applied to the calculation of the smearing of the foci of the Veselago lens due to the finite wavelength. We show that the Veselago lens is a unique optical instrument for the 3D imaging, but it is not a ``superlens'' as it has been claimed recently.Comment: 7 pages, 2 figure

Dielectric photonic crystal as medium with negative electric permittivity and magnetic permeability

We show that a two-dimensional photonic crystal (PC) made from a non-magnetic dielectric is a left-handed material in the sense defined by Veselago. Namely, it has negative values of both the electric permittivity $\epsilon$ and the magnetic permeability $\mu$ in some frequency range. This follows from a recently proven general theorem. The negative values of $\epsilon$ and $\mu$ are found by a numerical simulation. Using these values we demonstrate the Veselago lens, a unique optical device predicted by Veselago. An approximate analytical theory is proposed to calculate the values of $\epsilon$ and $\mu$ from the PC band structure. It gives the results that are close to those obtained by the numerical simulation. The theory explains how a non-zero magnetization arises in a non-magnetic PC.Comment: 11 pages 4 figure

The Effects of a Saffron Extract (affron®) on Menopausal Symptoms in Women during Perimenopause: A Randomised, Double-Blind, Placebo-Controlled Study

Objectives There is preliminary evidence suggesting saffron may effectively treat menopausal symptoms. The aim of this study was to examine the tolerability and efficacy of a standardised saffron extract (affron®) on menopausal complaints in perimenopausal women. Methods In this 12-week, parallel-group, double-blind, randomised controlled trial, 86 perimenopausal women experiencing menopausal complaints received either a placebo or 14 mg of a saffron extract (affron®), twice daily. Outcome measures included the Greene Climacteric Scale (GCS), Positive and Negative Affect Schedule (PANAS), and Short Form-36 Health Survey (SF-36). Results Based on data collected from 82 participants, saffron was associated with greater improvements in mood and psychological symptoms compared to the placebo. Results from the GCS revealed a significantly greater reduction in the GCS psychological score (P = 0.032), characterised by a 33% reduction in anxiety and a 32% reduction in depression scores from baseline to week 12. There was also a significantly greater reduction in the PANAS negative affect score (P = 0.043) compared to the placebo. However, compared to the placebo, saffron was not associated with greater improvements in vasomotor symptoms, somatic symptoms, or other quality of life measures. Saffron intake was well tolerated with no reported major adverse events. Conclusions The saffron extract, affron®, administered for 12 weeks at a dose of 14 mg twice daily was associated with greater improvements in psychological symptoms. Further studies in perimenopausal women presenting with varying severity of menopausal symptoms, using different doses of saffron will be useful to examine in future clinical trials

A randomized, double-blind, placebo-controlled, crossover study examining the hormonal and vitality effects of ashwagandha (Withania somnifera) in aging, overweight males

Ashwagandha ( Withania somnifera) is a herb commonly used in Ayurvedic medicine to promote youthful vigor, enhance muscle strength and endurance, and improve overall health. In this 16-week, randomized, double-blind, placebo-controlled, crossover study, its effects on fatigue, vigor, and steroid hormones in aging men were investigated. Overweight men aged 40-70 years, with mild fatigue, were given a placebo or an ashwagandha extract (Shoden beads, delivering 21 mg of withanolide glycosides a day) for 8 weeks. Outcome measures included the Profile of Mood States, Short Form (POMS-SF), Aging Males' Symptoms (AMS) questionnaire, and salivary levels of DHEA-S, testosterone, cortisol, and estradiol. Fifty-seven participants were enrolled, with 50 people completing the first 8-week period of the trial and 43 completing all 16 weeks. Improvements in fatigue, vigor, and sexual and psychological well-being were reported over time, with no statistically significant between-group differences. Ashwagandha intake was associated with an 18% greater increase in DHEA-S ( p = .005) and 14.7% greater increase in testosterone ( p = .010) compared to the placebo. There were no significant between-group differences in cortisol and estradiol. In conclusion, the intake of a standardized ashwagandha extract (Shoden beads) for 8 weeks was associated with increased levels of DHEA-S and testosterone, although no significant between-group differences were found in cortisol, estradiol, fatigue, vigor, or sexual well-being. Further studies with larger sample sizes are required to substantiate the current findings

The effects of Lutein and Zeaxanthin supplementation on cognitive function in Adults with Self-Reported mild cognitive complaints: A randomized, Double-Blind, Placebo-Controlled Study

Background: Lutein and zeaxanthin are fat-soluble, dietary carotenoids with high concentrations in human brain tissue. There have been a number studies confirming an association between lutein and zeaxanthin and cognitive function. Purpose: Examine the effects of lutein and zeaxanthin supplementation on cognitive function in adults with self-reported cognitive complaints. Study Design: Two-arm, parallel-group, 6-month, randomized, double-blind, placebo-controlled trial. Methods: Ninety volunteers aged 40–75 years received either 10 mg of lutein and 2 mg of zeaxanthin, once daily or a placebo. Outcome measures included computer-based cognitive tasks, the Cognitive Failures Questionnaire, Behavior Rating Inventory of Executive Function, Profile of Mood States, and the Patient-Reported Outcomes Measurement Information System-29. Results: Compared to the placebo, lutein and zeaxanthin supplementation was associated with greater improvements in visual episodic memory (p = 0.005) and visual learning (p = 0.001). However, there were no other statistically-significant differences in performance on the other assessed cognitive tests or self-report questionnaires. Lutein and zeaxanthin supplementation was well-tolerated with no reports of significant adverse effects. Conclusion: The results from this trial suggest that 6-months of supplementation with lutein and zeaxanthin may improve visual memory and learning in community-dwelling adults with self-reported cognitive complaints. However, it had no other effect on other computer-based measures of cognitive performance or self-report measures of cognition, memory, mood, or physical function

First results from the VIMOS-IFU survey of gravitationally lensing clusters at z~0.2

We present the on-going observational program of a VIMOS Integral Field Unit survey of the central regions of massive, gravitational lensing galaxy clusters at redshift z~0.2. We have observed six clusters using the low-resolution blue grism (R about 200), and the spectroscopic survey is complemented by a wealth of photometric data, including Hubble Space Telescope optical data and near infrared VLT data. The principal scientific aims of this project are: the study of the high-z lensed galaxies, the transformation and evolution of galaxies in cluster cores and the use of multiple images to constrain cosmography. We briefly report here on the first results from this project on the clusters Abell 2667 and Abell 68.Comment: 5 pages, 5 figures. To appear in "Sciences Perspectives for 3D Spectroscopy. ESO Astrophysics Symposia". Ed by M.Kissler-Patig, M.M. Roth and J.R. Wals