Occurrence Of Double Peaks Research Articles

Criticality of bistability phenomenon in deformed helix ferroelectric liquid crystal

The dynamics of bistability in deformed helix ferroelectric liquid crystal have been investigated by electro-optical method. The threshold value of the voltage required to switch the molecules of deformed helix ferroelectric liquid crystals (DHFLC) material has been studied by applying triangular wave pulse and texture observation under polarizing microscope. Two peaks have been observed in low and high frequency regimes on the application of triangular wave pulse to the sample. It has been proposed that the first peak is due to helix unwinding-winding process and the second is due to molecular reorientation process. The occurrence of double peak has been predicted to have close correlation with the observance of memory effect in DHFLC material, which is critically dependent on frequency and applied voltage, on the application of time delayed square wave pulse to the sample cell. The conditions for dynamic and static memory effects in DHFLC material have also been discussed in detail.

Latitude Dependence of the “Gnevyshev” Peaks and Gaps

The occurrence of double peaks near the maximum of sunspot activity was first emphasized by Gnevyshev (Solar Phys.1, 107, 1967) for the peak years of solar cycle 19 (1954 – 1964). In the present analysis, it is shown that double peaks in sunspot numbers were clearly visible in solar latitudes 10 – 30° N but almost absent in the southern latitudes, where some single peaks were observed out of phase by several months from any of the peaks in the northern latitudes. The spacing between the double peaks increased from higher to lower northern latitudes, hinting at latitudinal migration. In the next cycle 20 (1965 – 1976), which was of about half the strength of cycle 19, no clear-cut double peaks were seen, and the prominent peak in the early part of 1967 in the northern latitudes was seen a few months later in the southern latitudes. A direct relationship of Gnevyshev peaks with changes in the solar polar magnetic fields seems to be dubious. The commencements do not match.

Photoluminescence in high-quality a-Ge:H

We present quadrature frequency resolved spectroscopy (QFRS) measurements of photoluminescence (PL) in photoconductive and luminescent films of a-Ge:H with a defect density ≈ 1×10 16 cm −3 obtained from electron cyclotron resonance (ECR) plasma chemical vapor deposition (PCVD), together with a study of PL and PL excitation (PLE) spectra. A double-peak lifetime distribution is observed with a short lifetime at ≈ 1 μ s and a long one at ≈0.1 ms as observed in a-Si:H. The dependence of the two lifetimes and their corresponding relative quantum efficiencies on the e–h pair generation rate and temperature is also investigated. The occurrence of double peaks is attributed to the radiative recombination from singlet and triplet exciton states, and the exchange energy between singlet and triplet states is estimated to be ≈3.3 meV in a-Ge:H.

Acoustic characteristics of voice source for pathological voices: Some case studies.

The aim of this study is to examine the voice source signal of pathological voices. Pathological cases of vocal nodules, polyps, paralysis, malignancy, and laryngitis have been investigated. Some pre‐ and postoperative cases have also been studied. The sustained vowel /a/ of the subject has been recorded. The acoustic signal has been analyzed using an inverse filtering technique to obtain the voice source signal (derivative of glottal air flow). The voice source signal is displayed and marked for detailed examination. Acoustic recording, analysis, and marking is done using a VAGHMI system. For each type of pathology, certain consistent features deviating significantly from the normal cases have been noted in the voice source signal. For example, occurrence of double peak during the open phase, prolongation of the interval near glottal air flow peak, absence of clearly defined negative peak near epoch, etc. Interpretation of the voice source signal in terms of the vocal fold vibratory pattern and pathology has been attempted. Such an interpretation is validated against direct laryngoscopic observation where ever available. This on‐going study suggests the possibility of differential diagnosis of the vocal fold pathology by acoustic analysis of vowel sound.

Use of a pharmacokinetic model incorporating discontinuous gastrointestinal absorption to examine the occurrence of double peaks in oral concentration-time profiles.

Double peaks in the plasma concentration-time profile following oral administration have been reported for several compounds. A pharmacokinetic model incorporating discontinuous absorption was developed to simulate concentration-time profiles with double peaks. The gastrointestinal (GI) tract was divided into N compartments, with absorption occurring only from the second and Nth compartments. A two-compartment model was used to describe systemic drug disposition. The effect of gastric emptying and GI transit rate constants (Kl and K1, respectively), number of hypothetical gut compartments, and absorption rate constant at each site (Ka1, Ka2) on the time of occurrence of each peak (Tp1, Tp2), the theoretical fraction of the dose absorbed at each site (phi 1, phi 2), and the contribution of the second site to systemic drug exposure (expressed as phi 2rel) were examined. Simulated concentration-time profiles demonstrated that Tp2 was determined by Kt and N, while Tp1 was determined by K1 and Kt. Changes in Ka1 and Ka2 had no effect on Tp1 or Tp2. phi 1, phi 2, and phi 2rel were determined by Ka1, Ka2, and Kt, and simulations indicated that a secondary peak in the concentration-time profile will be evident only when phi 2rel is substantial. In addition, concentration-time data for ranitidine and cimetidine, which displayed double peaks, were fit with the model. The present model described both data sets well, and realistic pharmacokinetic and physiologic parameters (absorption rate constants, systemic bioavailabilities, GI residence times) were obtained.

Unusual Electrophoretic Patterns of Plasma Proteins in Human Subjects

Abstract Study of 313 plasma electrophoretic patterns from 158 hospitalized subjects revealed that 30 per cent of these patients exhibited a heterogeneity marked by occurrence of double peaks in the alpha-2 and 6 per cent in the beta globulin fraction. Occurrence of double peaks could not be related to any specific disease. Similar study of plasma from 18 normal adult subjects did not reveal double peaks in any of the protein fractions. Existence of prealbumin components, with mobilities greater than that of the albumin, has been observed in 6 of 158 pathological subjects. Mobilities and concentrations of components x1, x2, and x3 are reported.