Spectroscopic Diagnosis Research Articles

Spectroscopic diagnosis of cervical intraepithelial neoplasia (CIN) in vivo using laser‐induced fluorescence spectra at multiple excitation wavlengths

Background and Objective The diagnostic contribution of cervical tissue fluorescence spectra acquired in vivo at 380 and 460 nm excitation were analyzed using a general multivariate statistical algorithm. Materials and Methods The primary steps of the algorithm are to: (1) preprocess data to reduce interpatient and intrapatient variation of tissue spectra from the same diagnostic category, without a priori information, (2) dimensionally reduce the preprocessed spectral data using Principal Component Analysis, and (3) develop a probability based classification scheme based on logistic discrimination using the diagnostically useful principal components. The algorithm was tested on cervical tissue spectra acquired from 165 sites at 380 nm excitation and from 147 sites at 460 nm excitation. A retrospective and prospective estimate of the algorithm's performance was determined. Results At 460 nm excitation, (1) SILs can be differentiated from normal squamous tissues with an average sensitivity and specificity of 91% ± 1.3 and 75.5% ± 1, respectively; furthermore, (2) high grade SILs can be differentiated from low grade SILs with an average sensitivity and specificity of 80% ± 4 and 76% ± 5, respectively. In addition, using tissue spectra at 380 nm excitation, SILs can be differentiated from normal columnar epithelia and inflammation with an average sensitivity and specificity of 77% ± 1 and 72% ± 9, respectively. Conclusions Fluorescence spectra at multiple excitation wavelengths are essential for the detection and differential diagnosis of SILs at colposcopy. © 1996 Wiley-Liss, Inc.

Spectroscopic diagnosis of esophageal cancer: New classification model, improved measurement system

Laser-induced fluorescence spectroscopy was used to measure fluorescence emission of normal and malignant tissue during endoscopy in patients with esophageal cancer and volunteers with normal esophagus. The spectroscopy system consisted of a nitrogen-pumped dye-laser tuned at 410 nm for excitation source, an optical multichannel analyzer for spectrum analysis, and a fiberoptic probe designed for both the delivery of excitation light and the collection of fluorescence emission from tissue. The fluorescence lineshape of each spectrum was determined and sampled at 15-nm intervals from 430 to 716 nm. A calibration set of spectra from normal and malignant spectra was selected. Using stepwise discriminate analysis, significant wavelengths that separated normal from malignant spectra were selected. The intensities at these wavelengths were used to formulate a classification model using linear discriminate analysis. The model was then used to classify additional tissue spectra from 26 malignant and 108 normal sites into either normal or malignant spectra. A sensitivity of 100% and specificity of 98% were obtained. (Gastrointest Endosc 1995;41:577-81.)

Time-resolved Infrared Spectroscopic Diagnosis of a Bimolecular Chemical Reaction in Room Temperature Solution. The CCl3 Radical Produced from Photoexcited trans-Stilbene and Carbon Tetrachloride

Abstract The newly found photochemical reaction between trans-stilbene and carbon tetrachloride was examined with time-resolved infrared spectroscopy. On the photoexcitation of trans-stilbene in a carbon tetrachloride solution at room temperature, an intense infrared band was observed at 896 cm−1. This band is identified as a band from the trichloromethyl (CCl3) radical. It has been clarified that photoexcited trans-stilbene abstracts hydrogen from carbon tetrachloride to generate the CCl3 radical.

Spectroscopic diagnosis of vibrationally-hot N2

Electron-impact induced VUV emission measurements of the C'41 Sigma +u-X1 Sigma g+ and a1 Pi g-X1 Sigma g+ systems of N2 allow significant information about the vibrational character of an RF excited N2 beam to be obtained. The former system provides a rather accurate direct monitor of the v=0 population of the ground state whereas the latter allows conclusions to be drawn about the population in other states as well. The relative quantum efficiency of a CCD-based detection system used in some of the measurements is also established.

Spectroscopic diagnosis of long-scale-length exploding-foil plasma in the presence of an intense radiation field

An effective technique for measuring the local electron temperature and density of a laser-produced plasma involves analysis of the emission and/or absorption spectrum from an impurity dopant. However, when an intense high-energy radiation field is present the ionization balance, level population, and resulting spectrum produced by the impurity may be significantly perturbed. We are currently using several computer models to study the effects of such a radiation field for experimental conditions that could be obtained using the Nova laser facility, and are concentrating on the behavior of line intensity ratios that are typically used for density and temperature diagnosis. The goal of this work is to determine the feasibility of spectroscopic diagnosis when an intense high-energy radiation field is present.

Commission 14 : Atomic and Molecular Data (Donnees Atomiques et Moleculaires)

Since its creation, the Commission has been keen on activating the cross-discipline interaction between astrophysics and atomic and molecular physics. The need for a variety of atomic and molecular data has become more and more important for the recent past years. This need will certainly increase still more in the next years, due to the creation of new ground based instruments and to the launch of new space missions : they will produce large amounts of high resolution spectra from the X-rays to the infrared and millimeter wavelengths involving many atoms, ions and molecules. At the 1988 Baltimore meeting there was a general consensus that the aim of the Commission is to watch over the atomic and molecular spectral and structure data, together with the energy exchange processes in atomic and molecular physics relevant for astrophysics. In particular, the Commission is concerned by the interactions between photons and atoms (or ions or molecules), including wavelengths and line transition probabilities data, and by the interactions between particles, including atomic, molecular, ionic and electronic collision cross-sections, and by related phenomena, such as line broadening, collisional redistribution of radiation and line polarization. All these informations are essential for the interpretation of astronomical observations, such as spectroscopic diagnosis and theoretical modelling of astrophysical media.

Optical spectroscopic diagnosis of cancer and normal breast tissues: erratum

Optical spectroscopic diagnosis of cancer and normal breast tissues: erratum

Spectroscopic study of ablation in guided surface discharge plasmas

A spectroscopic study of gliding ablative discharges has been carried out on N(2), CO(2), and lasing mixtures of TEA CO(2) lasers. By spectroscopic plasma diagnosis techniques (local thermodynamic equilibrium assumed) we observed an inhomogeneous transversal distribution of the ablated elements. Electronic temperature and density transversal distributions are, however, fairly homogeneous. We also found a different ablation threshold for two ablated substrate elements. The ablation threshold seems to be related to the plasma current density. The results are of practical interest in the UV preionization of TEA CO(2) lasers.

Optical spectroscopic diagnosis of cancer and normal breast tissues

Steady-state fluorescence spectra and excitation spectra from native human normal and malignant tumor breast tissues have been measured and analyzed. Two types of spectra from normal tissues have been found and discussed. The statistics of the fluorescence results are given, and the reasons for false negative, false positive, and equivocal results are presented.

Chemical and Expansion Properties of Compact Planetary Nebulae in the Galactic Anti-Center Region

A spectroscopic diagnosis on M1-5, M1-9, K3-66, and K3-67 is presented. Our sample were chosen from the catalogue of radial velocities (Schneider et al 1983) by the reason of not only their kinetic peculiarity, but also apparently compact images. Main purpose is to analyze the chemical properties which should give us an information about galactic chemical abundance distribution in the direction of galactic anti-center region based upon kinetic peculiarity. Another one is to study on an expansion characteristics by which we can recognize intrinsically compact planetary nebulae in young phase.Spectroscopic observations were made at the Okayama Astrophysical Observatory (Shibata and Tamura 1985), the Steward Observatory, and Lick Observatory (Tamura and Shaw 1987).

Spectroscopic Diagnosis of SN1987A and Lesser Lights

AbstractSN 1987A gives a unique chance to study both the precursor star and the subsequent dynamical evolution of the explosion. Comparison of the light curves shows that either H0 ∼ 100 km/s/Mpc, or SN 1987A ejected significantly less 56Ni than ordinary Type II supernovae. Investigation of the stellar structure pertinent to SK -69 202 reveals multiple solutions. For given luminosity, effective temperature, core mass and core radius, there are two families of envelope mass, one with large envelope mass and one with small envelope mass. The small envelope mass solutions can be ruled out by considerations of kinematics and the light curve. Envelopes of moderate mass may avoid each of these problems, but must be helium rich to be structurally self-consistent.The spectrum in both the optical and the ultraviolet at about two days is fairly well represented by a hydrogen envelope with a power law density profile (ρ∝r-11 ) of one-quarter solar metallicity in LTE. Theoretical spectra at this early epoch tend to favor luminosities on the high side of observational estimates in order to ionize Ca II and prevent excessively strong lines at H and K and the infrared triplet, with some ramifications for distance estimates.The spectra of SN1987A present an interesting contrast to other SN II events. A McDonald Observatory spectrum of SN 1985H in NGC 3359 of uncertain epoch shows a very close resemblance to that of SN 1987A at about two month’s age, including the strong line at 607 nm attributed by Williams to Barium. SN 1985H may have been of the same class of event as SN 1987A.

Thomson scattering of laser light from a high pressure air arc discharge and its application to electron density measurement

Thomson scattering of laser light, which has been adopted for diagnosis of fusion plasmas, etc., is applied here to high pressure arc discharges as found in power circuit breakers, for measuring the electron density in the columns. The scattered light spectrum from the electrons in the high temperature air at 1 atm is theoretically calculated in the electron density range from 5.0*1019 to 1.8*1023 m-3. The notable aspect of light scattering under such high pressure conditions is that the scattered light spectrum has sharp satellite peaks on both sides of the incident laser wavelength, which are brought about by the plasma oscillation between electrons and ions. Actual measurements of the Thomson scattered light have been carried out on DC arcs of 10 to 40 A which are stabilised by axial air flow. The satellite peak is distinctly detected, as expected from calculations, at the wavelength 5.7 nm from the laser wavelength for 40 A arc current. The electron density around the arc axis is determined as 9.2*1022 m-3 from its profile analysis. This value of electron density shows a good agreement with that estimated from the spectroscopic diagnosis.

Use of Laue-geometry x-ray diffraction in the spectroscopy of laser plasmas

Laue x-ray crystal diffraction geometry offers a number of advantages for the spectroscopic diagnosis of laser plasmas. Applications of this diffraction configuration, such as absorption spectroscopy, time-resolved spectroscopy, and x-ray polarization measurements, are described.

High Resolution X-Ray Spectroscopy for Diagnostics of Single Tokamak Discharges

We report on an experiment which has been used to measure soft X-ray line emission spectra from highly charged impurity elements in the hot plasma of the Alcator C tokamak. These measurements shall serve as a diagnostic of plasma parameters: the temperature (of ions and electrons), the electron and impurity ion densities, and charge state distributions. Results from the initial measurements of the He- and H-like spectra of S and Cl are presented as well as spectra from molybdenum in charge states between Mo28+ and Mo32+. Dependencies of the measured spectra on plasma parameters are provided. The aim of this experiment is to conduct broad-band time-resolved spectroscopic diagnosis of tokamak plasmas. To this end we discuss pertinent requirements of spectrometer performance and the development of a new position sensitive X-ray detector system.

Collisional-radiative-equilibrium spectroscopic diagnosis of a compressed, optically thick neon plasma

By self-consistently calculating x-ray spectra from first principles, we have delineated the relationships between the spectrum and the state of compression and heating of a neon plasma in detail. A collisional-radiative model including Stark line profiles is used to determine the highly ionized high-density states of neon. One of our calculated spectra reproduces remarkably well an experimental spectrum obtained from laser implosion by Yaakobi et al. and indicates compression conditions significantly different from those obtained assuming the validity of local thermodynamic equilibrium. Implications of our calculations for spectroscopic diagnoses of fusion plasmas are discussed.

X-ray spectroscopic diagnosis of laser-produced plasmas, with emphasis on line broadening

A detailed account is given of the x-ray spectroscopic diagnosis of plasmas formed by exploding pusher microballoons. The measurements of the electron temperature from the shell and from the core is described. A method for self-consistently fitting all the observed lines of one state of ionization is shown, giving a diagnosis for the electron density and the opacity. Further, it is shown that the self-consistency is only achieved when full line-broadening calculations, taking into account the shifts and asymmetries dependent on the charge of the emitter, are used for the optically thin profiles. It is also shown that non-local-thermodynamic-equilibrium effects are important in the description of the radiation transfer.