Biomedical subjects

L Halonen

Publications and source records attributed to L Halonen.

8 recordsLinked to original sources

PubMed2006

Visual performance in night-time driving conditions.

This paper introduces an experimental multitechnique method which was developed to establish a basis for a task performance-based mesopic photometry. This approach considers night-time driving by dividing visual performance into three visual tasks, of which achromatic threshold and reaction time are presented. The performance of both visual tasks decreased with decreasing luminance level from 1 to 0.01 cd m(-2), showing the strong effect of light level on visual performance in driving. The behaviour of the achromatic contrast threshold and reaction time for low-contrast targets was similar in terms of spectral effects, the strongest effects occurring at the lower mesopic levels. Both measures showed the Purkinje shift with decreasing luminance levels. The experimental data were used to calculate mesopic performance measures with the new mesopic model. The results imply that compared with V(lambda), spectral sensitivity in night-time driving can be better described with a mesopic model based on visual performance measures.

Adult↗

PubMed2004

First stretching overtone of BiH3: an extreme local-mode case for XH3-type molecule?

The first stretching overtone region of short-lived, formerly inaccessible BiH3 near 3405 cm(-1) has been measured by Fourier-transform infrared spectroscopy with a resolution of 0.0066 cm(-1). Only the 2nu1(A1)/nu1+nu3(E) band system has been observed. Rotational analysis, with transitions reaching J'max=14, has revealed almost perfect local-mode behavior for the upper states denoted as (200A1/E) in the local-mode notation. Ratios of vibration-rotation interaction parameters q(eff)/alpha(eff)(BB) and r(eff)/alpha(eff)(BC), and the appropriate rotational constant differences, are in good agreement with theoretical local-mode limit values. A simple stretching vibrational model reproduces the observed vibrational term values well, and the potential parameters obtained are close to true values.

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PubMed1999

High-Resolution Infrared Spectrum of nu5, nu4, nu3, nu4 + nu5, and 2nu4 Band Systems of Deuterobromoacetylene.

High-resolution vibration-rotation spectra of gas-phase deuterobromoacetylene have been recorded in the 240-990 cm-1 infrared region. The analyzed band systems are rich in hot bands and have a high density of lines. Five band systems and a total of 124 vibration-rotation bands of the isotopic species DCC79Br and DCC81Br have been rotationally analyzed. Accurate rotational parameters and vibrational wavenumbers for 33 vibrational states of each species have been obtained from the rotational analysis. l doubling and rotational l resonance have been observed on some states and the respective resonance parameters have been obtained through nonlinear least-squares optimization. A Fermi resonance block model with perturbation terms has been used for the analysis of the vibrational states. With optimized parameters, the model produces root-mean-square deviations of observed - calculated wavenumbers of about 0.3 cm-1 for both isotopic species. Copyright 1999 Academic Press.

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PubMed1998

High-Resolution Photoacoustic Overtone Spectrum of Monobromoacetylene, HCCBr, above 11 600 cm-1

Photoacoustic overtone spectra of monobromoacetylene, HCCBr, have been recorded in the wavenumber region 11600-13400 cm-1 using a titanium:sapphire ring laser spectrometer. All together, eight overtone bands of HCC79Br and eight bands of HCC81Br have been observed in the rotational analysis. A Fermi resonance model based on conventional normal coordinate theory has been used to vibrationally assign the rotationally analyzed bands. The resonance model employed reproduces well the observed vibrational band origins and rotational constants. Copyright 1998 Academic Press. Copyright 1998Academic Press

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PubMed1998

High Resolution FTIR Study of the nu5 Bands of HSiD3 and H120SnD3

High resolution Fourier Transform spectra of HSiD3 and monoisotopic H120SnD3 have been recorded in the region of the nu5 fundamental at 850.68 and 646.90 cm-1 with a resolution of 3.3 and 2.8 x 10(-3) cm-1, respectively. About 2000 rovibrational transitions of each species have been assigned and fitted to two different reductions of the effective Hamiltonian, with sigma(Fit) = 1.2 x 10(-4) (HSiD3) and 1.4 x 10(-4) cm-1 (H120SnD3). The two sets of parameters were shown to be equivalent, and relations between parameters belonging to different reductions are perfectly fulfilled. Furthermore the ground state constants C0 and DK0 have been determined for the first time. For consistency the previously measured data belonging to the nu5 band of H70GeD3 have been refitted, sigma(Fit) = 1.6 x 10(-4) cm-1, on the basis of improved ground state parameters including the h'3 term accounting for the splitting of the K = 3 level. Copyright 1998 Academic Press.

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PubMed1997

High Resolution Study of the nu2 , 2nu1 , nu1 + nu3 , and 2nu3 Bands of Hydrogen Telluride: Determination of Equilibrium Rotational Constants and Structure

High resolution Fourier transform spectra of a natural and a 130 Te monoisotopic sample of H2 Te have been recorded at a resolution of 0.0022 cm-1 in the 11.6 μm spectral region, as well as a spectrum of a natural sample of H2 Te at a resolution of 0.0051 cm-1 in the 2.4 μm region. In the 11.6 μm region the main absorbing band is the nu2 band, the analysis of which was rather easy. On the other hand, in the 2.4 μm region three bands are absorbing, namely 2nu1 , nu1 + nu3 , and 2nu3 , the last being much weaker than the others. The analysis in this spectral domain was much more difficult because of resonances. Indeed it proved not possible to reproduce the observed lines without taking into account the Darling-Dennison interaction between the levels of the (200) and (002) states and the Coriolis interactions between the levels of (200) and (101) and between those of (101) and (002). Considering these interactions allowed us to calculate very satisfactorily all the experimental levels, and precise sets of vibrational energies and rotational and coupling constants were obtained for the seven most abundant H2 Te isotopic species, namely H2 130 Te, H2 128 Te, H2 126 Te, H2 125 Te, H2 124 Te, H2 123 Te, and H2 122 Te. For the most abundant species, H2 130 Te, the band centers in cm-1 are nu0 (nu2 ) = 860.6563, nu0 (2nu1 ) = 4062.8842, nu0 (nu1 + nu3 ) = 4063.3697, and nu0 (2nu3 ) = 4137.0454. These results, combined with those obtained for other vibrational states, have been used to derive the equilibrium rotational constants and their corrections. Finally, by neglecting the electronic corrections, the equilibrium structure of H2 130 Te was obtained as follows: r e (Te-H) = 1.65145(10) A, alphae (HTeH) = 90.2635(90)degrees.

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PubMed1997

High-Resolution FTIR and Photoacoustic Overtone Spectrum of HCCI

The first and second C-H overtone vibration-rotation absorption spectra of monoiodoacetylene (HCCI) have been recorded using an FTIR spectrometer with an instrument resolution of about 0.005 cm-1 (0.9/MOPD). The third overtone spectrum has been obtained using a titanium:sapphire ring laser spectrometer with a spectral resolution of about 0.02 cm-1. Due to anharmonic resonances like Fermi and Darling-Dennison resonances, accompanying bands can be observed close to the main overtone band. All the observed bands have been rotationally analyzed. Published vibrational data together with present results are used in a model which includes anharmonic resonances. Vibrational assignments of the observed bands are based on this calculation. The agreement between calculated and observed energy levels is good considering the amount of data available. Copyright 1997 Academic Press. Copyright 1997Academic Press

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PubMed1991

Sleep and cardiac rhythm in healthy men.

Cardiac rhythm during sleep was analysed in 168 healthy men aged 19 to 30 (mean 21.8) years using continuous nocturnal ECG recordings. Thirty five of the subjects were endurance athletes; 99 were recorded at home and 69 at a garrison during military service. The number of short term (less than one min) accelerations of heart rate of more than ten beats per minute ranged from 1.3 to 14.3 per hour; the number or accelerations (greater than one min) of more than 25 beats per minute typical of nocturnal restlessness ranged from zero to 6.1 per hour. The accelerations indicating nocturnal restlessness were more common during recordings done at the garrison than at home (2.2 per hour vs 1.3 per hour, P less than 0.01), whereas the short term accelerations were not (5.8 per hour vs 5.1 per hour, NS). Sinus pauses exceeding 2.00 sec occurred in 17 men (13 in athletes), occasional second degree atrioventricular block in 19 (eight in athletes) and ventricular premature beats in 37. Eighty-two per cent of sinus pauses, 83% of second degree atrioventricular blocks, and 81% of ventricular premature beats (when less than ten in the same subject) were associated with short term changes in heart rate. In conclusion, rapid changes in heart rate, presumably as a results of autonomic activation, are closely associated with most arrhythmias in healthy men during sleep, whereas changes in heart rate typical of nocturnal restlessness have little arrhythmogenic effect.

Adult↗