ABSTRACT
A reflection grating with a binary surface profile is presented that has high diffraction efficiency. The measured intensity for the + 1st diffracted order was 77%. The binary grating is composed of a minilattice with feature sizes comparable with the wavelength of the incident light. The overall structure is designed in such a way that it imitates a conventional blazed grating. The grating also has interesting polarization properties. The main part of the TE-polarized light is diffracted into the 1st diffracted order, and most of the TM-polarized light remains in the 0th diffracted order. The measurements of the grating are compared with rigorous diffraction theory and found to be in reasonable agreement.
ABSTRACT
We evaluated the effects of a single oral dose of 5 mg of isradipine compared to placebo in a randomized, double-blind, crossover study using gated radionuclide angiography at rest and during exercise in 20 patients with stable chronic angina. Isradipine improved both anginal symptomatology and ST-segment depression during exercise, with a concomitant favorable effect on the isotopic parameters exploring systolic and diastolic left ventricular function. There was a marked increase of the ejection fraction during exercise with isradipine compared to placebo (61 +/- 14% vs. 55 +/- 15%, respectively, p less than 0.001) as well as a significant improvement in the peak ejection rate and the peak filling rate at rest [2.56 +/- 0.62 vs. 2.16 +/- 0.54 end diastolic volume (EDV) per second and 2.14 +/- 0.59 vs. 1.87 +/- 0.37 EDV/s, respectively] and during exercise (3.49 +/- 0.97 vs. 3.10 +/- 1.07 EDV/s and 4.05 +/- 1.34 vs. 3.65 +/- 1.25 EDV/s, respectively). We conclude that isradipine has a beneficial effect on the clinical and electrocardiographic signs of exercise-induced ischemia, leading to a significant improvement of the systolic and diastolic parameters of left ventricular function. Therefore, isradipine is potentially a useful treatment for patients with exertional angina and hypertension, alone or associated with beta blocker medication.
Subject(s)
Angina Pectoris/drug therapy , Calcium Channel Blockers/therapeutic use , Dihydropyridines/therapeutic use , Exercise/physiology , Rest/physiology , Ventricular Function, Left/drug effects , Adult , Aged , Angina Pectoris/diagnostic imaging , Angina Pectoris/physiopathology , Angiocardiography , Blood Pressure/drug effects , Double-Blind Method , Echocardiography , Electrocardiography/drug effects , Female , Gated Blood-Pool Imaging , Heart/diagnostic imaging , Heart Rate/drug effects , Hemodynamics/drug effects , Humans , Isradipine , Male , Middle AgedABSTRACT
Zero-order gratings are grating structures with a period that is small compared with the wavelength of light. Only the directly transmitted or reflected light, the zero diffraction order, is nonevanescent and propagates in a distance from the grating. Thus the grating behaves like a slab of ordinary homogeneous material with an effective refractive index. By varying the material composition, i.e., by variation of the duty cycle of the grating, the effective refractive index can be changed. A grating with variable duty cycle therefore behaves like a material with distributed index. Based on such artificial materials, distributed-index elements are proposed. The physical principle is demonstrated with water waves.
