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Biomedical subjects

G Pierre

Publications and source records attributed to G Pierre.

18 recordsLinked to original sources
PubMed2000

New Accurate Fit of an Extended Set of Saturation Data for the nu(3) Band of SF(6): Comparison of Hamiltonians in the Spherical and Cubic Tensor Formalisms.

An extended set of 321 frequencies of vibration-rotation lines of the nu(3) band of SF(6) has been measured by saturation spectroscopy using various isotopic species of CO(2). A least-squares fit of these data has been performed using an effective Hamiltonian written either with a spherical tensor or with a cubic tensor formalism. We have derived correspondence formulas between the parameters in the two approaches and checked that both formalisms give the same results up to the seventh order. Corrected parameters are given for the fit with a fifth-order Hamiltonian. An accurate representation of the band is obtained at the tenth order (standard deviation approximately 12 kHz) with a remarkable predictive power (better than 40 kHz) for J values </= 100. The convergence properties of the Hamiltonian power expansion are discussed. Copyright 2000 Academic Press.

Journal Article↗
PubMed2000

Simultaneous Analysis of the nu(2) Raman and nu(2) + nu(6) Infrared Spectra of the SF(6) Molecule.

High-resolution Raman spectra of the nu(2) band of SF(6) have been recorded at a temperature of 195 K (dry ice) and a pressure of 39 mbar. These spectra were analyzed using a new set of programs specially written for XY(6) molecules. These programs, called HTDS (highly spherical top data system) in reference to the set of programs called STDS (spherical top data system written for XY(4) molecules) can be freely accessible through ftp (user anonymous) at jupiter.u-bourgogne.fr or on the web at the URL http://www.u-bourgogne.fr/LPUB/shTDS.html. The study of nu(2) was made using a Hamiltonian developed through the third order. Four parameters were determined. The standard deviation obtained using about 559 data up to J < 61 is 0.0021 cm(-1). This result is used to refine by simultaneous analysis the nu(2) and nu(2) + nu(6) bands of SF(6). This new fit allows the determination for the first time of some nu(6) parameters. The values obtained for this band (forbidden in Raman and in infrared) will be used to study the infrared hot bands in the nu(3) and nu(4) regions. Copyright 2000 Academic Press.

Journal Article↗
PubMed1999

Analysis of the Infrared Fourier Transform Spectrum of the Spectra of Silane in the Range 2930-3300 cm(-1).

The infrared spectrum of (28)SiH(4) between 2930 and 3300 cm(-1) was recorded using the Laboratoire de Physique Moléculaire et Applications (LPMA.) Fourier transform spectrometer. The instrumental response function width chosen makes it possible to obtain a Doppler-limited spectrum. The observed spectrum belongs to the tetrad built with one quantum of stretching mode (nu(1) or nu(3)) and one quantum of bending mode (nu(2) or nu(4)). The excited states are formed from eight vibrational sublevels: nu(1) + nu(2)(E), nu(1) + nu(4)(F(2)), nu(2) + nu(3)(F(1) + F(2)), and nu(3) + nu(4)(A(1) + E + F(1) + F(2)). The intricacy of the upper states was resolved using the variations of the line strength between the 297 K and 209 K spectra and the precise knowledge of the ground state. For analysis with the vibrational extrapolation method, we used the previous results for the fundamental bending dyad (nu(2)/nu(4)) and the stretching dyad (nu(1)/nu(3)). The Hamiltonian is expanded through the sixth order of approximation for the ground and the bending states, the fifth order for the stretching states, and the fourth order for the tetrad states in the Amat-Nielsen classification. About 1033 pieces of data are used in the analysis and the weighted standard deviation obtained is 4.6 x 10(-3) cm(-1). Copyright 1999 Academic Press.

Journal Article↗
PubMed1998

High-Resolution Jet-Cooled Spectroscopy of SF6: The nu2 + nu6 Combination Band of 32SF6 and the nu3 Band of the Rare Isotopomers.

The Fourier transform infrared spectrum of SF6 was recorded in a supersonic expansion jet of an SF6/argon mixture. The SF6:Ar seeding ratio was 2:3. The instrumental bandwidth was 0.005 cm-1. A globar source and an MCT detector were used. A rotational temperature of approximately 30 K was achieved. The nu2 + nu6 combination band of 32SF6 was analyzed using a modified version of the spherical top data system (STDS) programs developed in Dijon. A very good fit was obtained for this band with an rms of 0.0036 cm-1. The effective Hamiltonian was developed up to fourth order for the nu2 + nu6 part, to second order for the nu2 and ground state parts, and to first order for the nu6 part. Five hundred twenty-one transitions were assigned, 40 of them reaching the F2u forbidden sublevel. The positions of the two F1u and F2u sublevels are found to be 991.276 and 989.487 cm-1, respectively. The nu3 band of the 33SF6 and 34SF6 isotopomers were also analyzed. Parameters and simulations are presented. A first detection of the nu3 Q branch of 36SF6 (0.02% natural abundance) is reported. Copyright 1998 Academic Press.

Journal Article↗
PubMed1997

Study of the v3 = 1 State of 80SeF6 by Fourier Transform Spectroscopy

The Fourier transform infrared spectrum of monoisotopic 80SeF6 has been recorded in the 760-792 cm-1 region with an effective resolution of ca. 2.3 x 10(-3) cm-1. The 80SeF6 sample was prepared by burning monoisotopic 80Se powder (99.2%) in an excess of fluorine. The analysis of infrared transitions of the nu3 band enabled the determination of parameters of the Hamiltonian developed up to the third order and the fourth order. The standard deviation obtained is equal to 4 x 10(-4) cm-1 for the third-order development and 3.2 x 10(-4) cm-1 for the fourth-order development. In the two analyses, 2900 lines were assigned and fitted. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1986

[Intermediate neurological development of 60 neonates weighing 1500 grams or less at birth. Predictive value of initial findings (clinical aspects, electroencephalograms and brain imaging)].

60 low birthweight (less than or equal to 1,500 g) are distributed according to existence or not, and intensity of brain disturbances, during the neonatal period; appreciated by neurological examinations, early EEG and brain imaging during the second month of life. At 18 months, at least, neurological outcome is normal for 46 children (but 6 had transient neuromotor anomalies), 14 have sequelae (7 mild, 7 major). All children with clinical neurological examination carried out during the neonatal period are normal at follow up. It is true also for the children without EEG anomaly and normal brain imaging. The early prediction of neurological outcome can be made easily with consideration of these three data. Standardised test are proposed, during the neonatal period, for these low birth weight infants.

Brain↗
PubMed1984

Precocious thymic involution manifest by epithelial injury in the acquired immune deficiency syndrome.

Thymuses from six heterosexual Haitian patients with the acquired immune deficiency syndrome (AIDS) were studied by light microscopy and the findings were compared with those from three control groups. The control groups included 1) five age-matched Haitian hospital patients; 2) ten age- and sex-matched Montreal patients who had died suddenly or had had brief illnesses; and 3) 20 middle-elderly Montreal patients who had experienced chronic, wasting illnesses or prolonged hospitalization. Thymuses from patients with AIDS demonstrated pronounced involution, effacement of the cortex and medulla, marked thymocyte depletion, variable degrees of plasma cell infiltration and fibrosis, and, above all, absence of Hassall's corpuscles. Thymuses from Haitian and Montreal control subjects who had died suddenly or had brief illnesses demonstrated minimal involution and abundant Hassall's corpuscles. Although thymuses from 12 of the chronically ill control subjects demonstrated marked involution, architectural effacement, and absence of Hassall's corpuscles, partial architectural preservation and variable numbers of Hassall's corpuscles were observed in eight of these subjects. Thus, the extent of thymic involution observed in patients with AIDS antedates that incurred with aging and supersedes that induced by sustained stress and inanition. The loss of Hassall's corpuscles in patients with AIDS suggests that the thymic epithelium either incurs a form of injury or undergoes precocious involution during the illness. Whether this lesion is central to the pathogenesis of AIDS or merely a reflection of intense, sustained stress coupled with accelerated physiologic involution is unknown. It is possible that the disappearance of Hassall's corpuscles may indicate important, although as yet cryptic events within the thymic microenvironment in this syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1983

[Clinical tolerance of hemodialysis sessions in children. Comparison of bicarbonate and acetate baths].

Hemodialysis tolerance was studied in 3 children during periods of respectively 6, 7 and 9 months comparing bicarbonate (B) versus acetate (A) with equivalent number of sessions. Parameters used for tolerance in these three cases were: hypotensive bouts, solutes perfused during sessions, mean alimentary intake, vomiting, headache, abdominal pain and benzodiazepine prescriptions, taking account of ultrafiltration and dry weight variations during this periods. Results with bicarbonate are following: Obs. n degrees 1 (11 year old female, cystinosis, A: 38 sessions, B: 44 sessions): significant improvement of hypotension episodes and reduction of solutes perfused (p less than 0,05), of vomiting (p less than 0,001), and increase of mean alimentary intake (p less than 0,001). Obs. n degrees 2 (11 year old male, glomerular nephropathy, A: 25 sessions, B: 27 sessions): non significant improvement of hypotension episodes, but improvement for mean alimentary intake (p less than 0,01). Obs. n degrees 3 (4 year old male, uropathy with renal hypoplasia): no significant improvement, but for this child A hemodialysis tolerance was better than for both others. B hemodialysis seems a good alternative for children with A intolerance.

Acetates↗
PubMed1981

Spirometric standards for healthy black adults.

Forced expiratory spirometric studies were performed on 512 nonsmoking black adult men and women with negative cardiorespiratory histories. Regression equations were calculated for forced vital capacity (FVC), percent vital capacity in 1 second (% FEV(1)), and forced midexpiratory flow rate FEF(25-75)%), using height and age. These equations resulted in predicted values 3.5 to 23 percent lower than commonly used standards. The wide range of variation means that a single correction factor is inadequate when considering ethnic differences. In contrast, FEV(1)/FVC was within the accepted range of normal for all ethnic groups. In the 30 percent of subjects in whom sitting height was measured, it was not significantly different from one half the standing height; thus, sitting height is also an inadequate correction factor. Tables of predicted values were constructed for easy reference, with the hope that use of racespecific standards for pulmonary function testing will become widespread.

Adult↗