| 1. |
- Bengtsson, G. J, et al.
(författare)
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Natural Lifetimes of Excited-states of Neutral Nitrogen Determined By Time-resolved Laser Spectroscopy
- 1992
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 45:5, s. 2712-2715
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Tidskriftsartikel (refereegranskat)abstract
- Radiative lifetimes were determined for three quartet states of neutral nitrogen, and sequences of Rydberg states were studied using depletion spectroscopy. Free nitrogen atoms were generated by photodissociation of N2O using frequency-tripled dye-laser radiation that was two-photon resonant with the 2p(2)3p 4S or 4D states. Further quartet states were reached by a subsequent single-photon absorption. We obtain tau(2p(2)3p 4D7/2) = 44(2) ns, tau(2p(2)3p 4S3/2) = 26.0(1.5) ns, and tau(2p(2)6s4P5/2) = 41(7) ns.
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| 2. |
- Länne, T, et al.
(författare)
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Diameter and compliance in the male human abdominal aorta: influence of age and aortic aneurysm
- 1992
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Ingår i: European Journal of Vascular Surgery. - 0950-821X. ; 6:2, s. 178-184
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Tidskriftsartikel (refereegranskat)abstract
- In this study changes in the diameter and compliance of the distal abdominal aorta (76 healthy Caucasian males, 5-71 years old) were determined non-invasively and related to age by means of an ultrasound phase-locked echo-tracking system. The diameter of the aorta increased not only in the period between 5 and 25 years of age, but also by about 30% between the ages of 25 and 71. The pressure diameter curves at 25, 51 and 70 years were non-linear with flattening between 90 and 110 mmHg, and the slope of the curves declined with age. Thus, the pressure strain elastic modulus (Ep) and stiffness (beta) increased (i.e. compliance decreased) in an exponential manner according to age. A group of 37 males with aneurysmal widening of the distal abdominal aorta had a significant increase in Ep when compared to an age-matched control group. Furthermore, the ranges for both Ep and beta were much larger in the aneurysm group than in the control group, indicating diversity in the pathogenesis of the disease. The non-invasive ultrasonic method of phase-locked echo-tracking is an appropriate method for studying compliance in major arteries under a variety of pathophysiological conditions.
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| 3. |
- Länne, T, et al.
(författare)
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Noninvasive measurement of diameter changes in the distal abdominal aorta in man
- 1992
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Ingår i: Ultrasound in Medicine and Biology. - 0301-5629. ; 18:5, s. 451-457
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Tidskriftsartikel (refereegranskat)abstract
- An ultrasound phase-locked, echo-tracking system was used to determine the dynamic properties of the distal abdominal aorta in 10 Caucasian male subjects (mean age, 25 years). Recordings were made at rest and during the blood pressure increase resulting from isometric exercise. The pressure diameter curve was nonlinear with an inflection at about 90-110 mmHg. Above this pressure range, the vessel was stiffer (less compliant), but the pressure diameter relationship was roughly linear above as well as below the inflection. Individual pressure diameter curves showed hysteresis, i.e., the aorta had a smaller diameter during expansion than during retraction at corresponding pressures. The pressure strain elastic modulus (Ep) and stiffness (beta) were at rest [Mean Arterial Pressure (MAP), 81 mmHg] 0.70 10(5) N/m2 and 6.0, respectively. During isometric exercise (MAP, 122 mmHg), Ep increased significantly by 91% and stiffness (beta) nonsignificantly by 27%. The variability of the compliance determinations was 5% when the ultrasonic system was combined with intra-arterial blood pressure measurements and less than 7% when combined with auscultatory blood pressure measurements. It is concluded that the phase-locked, echo-tracking system fulfills clinical requirements for routine measurements of vascular compliance.
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| 4. |
- Bengtsson, H, et al.
(författare)
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Expansion pattern and risk of rupture of abdominal aortic aneurysms that were not operated on
- 1993
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Ingår i: European Journal of Surgery. - 1102-4151. ; 159:9, s. 461-467
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To analyse the outcome of selective management of patients with abdominal aortic aneurysms, the expansion patterns of the aneurysms, and the factors that influenced the rate of rupture. DESIGN: Retrospective study. SETTING: Malmo General Hospital, Lund University, Malmo, Sweden. SUBJECTS: 155 patients (96 men and 59 women) with abdominal aortic aneurysms who were not selected for operation for whatever reason were included in the study immediately after their first ultrasound scan. MAIN OUTCOME MEASURES: Mortality, expansion rate (mm/year) measured on ultrasound scan, and rate of rupture of aneurysm. RESULTS: Median aneurysmal diameter was 40 mm (range 20-80), and length (n = 106) 70 (range 28-140). The patients were followed up for a median of 3.4 years (range 0-10.2). A total of 107 patients died and in 21 the aneurysms ruptured (4 were operated on and survived). Thirteen patients were re-evaluated and operated on electively. Ultrasonography was repeated in 98 patients, the median expansion rates (mm/year) were 3.1 (diameter) and 1.9 (length). There was a significant linear relationship between initial size (diameter and length) and rate of expansion of diameter. The risk of rupture was greater in larger aneurysms that were expanding more quickly. The cumulative mortality was not affected by the 21 aneurysms that ruptured. CONCLUSION: Selective management of patients with aortic aneurysms is justified.
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| 5. |
- Bengtsson, H, et al.
(författare)
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Prevalence of abdominal aortic aneurysm in the offspring of patients dying from aneurysm rupture
- 1992
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Ingår i: British Journal of Surgery. - : Oxford University Press (OUP). - 1365-2168 .- 0007-1323. ; 79:11, s. 1142-1143
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Tidskriftsartikel (refereegranskat)abstract
- The prevalence of abdominal aortic aneurysm (AAA) is high in the brothers of patients with aneurysm. A genetic component in the development of AAA has, therefore, been postulated. In this study the offspring of patients who had died from AAA rupture were invited to undergo ultrasonography of the abdominal aorta. The attendance rate was 69 per cent. Thirty-nine sons of median age 60 (range 45-75) years and 23 daughters of median age 62 (range 42-80) years were examined. Abdominal aortic dilatation was found in eight men and one woman. The presence of aortic dilatation in these nine cases was not related to age, hypertension, smoking or symptoms of occlusive arterial disease. It is concluded that the sons of those who have died from ruptured AAA constitute a high-risk group for the development of this condition and should be considered for further screening.
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| 6. |
- Bengtsson, Lars, et al.
(författare)
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Water balance for landfills of different age
- 1994
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Ingår i: Journal of Hydrology. - 0022-1694 .- 1879-2707. ; 158:3-4, s. 203-217
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Tidskriftsartikel (refereegranskat)abstract
- Water-related processes in landfills are discussed with emphasis on internal processes such as field capacity, moisture variation in time and space, and macropore flow. Runoff production and evaporation from landfills in Sweden of different age are investigated. It is clarified in what ways and for how long a closed municipal landfill differs from an ordinary land area from a hydrological point of view.
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| 7. |
- Bengtsson, Per-Erik, et al.
(författare)
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Vibrational CARS thermometry in sooty flames: Quantitative evaluation of C2 absorption interference
- 1990
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Ingår i: Combustion and Flame. - 0010-2180. ; 82:2
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Tidskriftsartikel (refereegranskat)abstract
- The application of nitrogen vibrational CARS thermometry to sooty, premixed, atmospheric pressure flames has been investigated using a Nd:YAG laser based system. It was found that laser-produced C2 radicals strongly absorb part of the fundamental band peak in the CARS spectrum. This was the most severe interference to the CARS signal. A quantitative investigation of temperature errors caused by the C2 absorption effect is presented. The correlation between the absorption interference and the soot volume fraction was examined for different flame conditions. Also, the increase of the nonresonant susceptibility in sooty flame regions is clearly illustrated and its effect on thev evaluated temperature is quantitatively determined. The single-shot temperature standard deviation has also been investigated in flames with different soot loadings. Finally, other interference effects to the CARS signals in sooty flames are described and discussed.
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| 8. |
- Lycksell, P O, et al.
(författare)
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Sequence specific 1H-NMR assignments and secondary structure of a carboxy-terminal functional fragment of apolipoprotein CII.
- 1992
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Ingår i: European Journal of Biochemistry. - 0014-2956 .- 1432-1033. ; 205:1
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Tidskriftsartikel (refereegranskat)abstract
- The structural properties of a synthetic fragment of human apolipoprotein CII (apoCII) has been studied by circular dichroism and proton nuclear magnetic resonance. The fragment corresponds to the carboxy-terminal 30 amino acid residues and retains the ability of apoCII to activate lipoprotein lipase. Like native apoCII, the fragment has a tendency to self-associate in pure aqueous solution. Addition of 1,1,1,3,3,3-hexafluoro-2-isopropanol to aqueous solvent dissolves the aggregates and leads to an increase in the alpha-helical content of the peptide, probably by stabilizing transient helical structures. The resonances in the 1H-NMR spectrum of the fragment in 35% (CF3)2CHOH were assigned through standard procedures from nuclear Overhauser enhancement spectroscopy, correlated spectroscopy and total correlated spectroscopy experiments. The NMR data indicates the formation of a stable alpha helix spanning Ile66-Gly77. Another alpha helical turn may be formed between Lys55 and Ala59 and possibly span even further towards the carboxyl terminus. These structural elements are different from those previously predicted for this part of the sequence of apoCII.
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| 9. |
- Wu, Wen-Qi, et al.
(författare)
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Electrophysiological and behavioral responses of turnip moth males, Agrotis segetum to fluorinated pheromone analogs
- 1993
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Ingår i: Journal of Chemical Ecology. - 0098-0331. ; 19:1, s. 143-157
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Tidskriftsartikel (refereegranskat)abstract
- The electrophysiological and behavioral responses of male Agrotis segetum to fluorinated analogs of (Z)-5-decenyl acetate (Z5-10:OAc) were investigated. The single sensillum recordings showed that 4,4-difluoro-(Z)-5-decenyl acetate (4,4-F2), 7,7-difluoro-(Z)-5-decenyl acetate (7,7-F2), 10,10,10-trifluoro-(Z)-5-decenyl acetate (10,10,10-F3) and 7,7,8,8-tetrafluoro-(Z)-5-decenyl acetate (7,7,8,8-F4) were each 100-fold less active than the natural Z5-10 : OAc, whereas the 7,7,8,8,9,9,10,10,10-nonafluoro-(Z)-5-decenyl acetate (F9) analog was essentially inactive. A mixture of Z5-10 : OAc, Z7-12 : OAc, and Z9-14 : OAc on a filter paper dispenser was as attractive as female gland extracts when tested in a flight tunnel. With Z5-10:OAc omitted, the two-component mixture elicited a significantly lower male response. Four analogs, 7,7-F2, 10,10,10-F3, 7,7,8,8-F4, and F9, were added separately to the two-component mixture to replace Z5-10:OAc. The responses elicited by the mixtures containing the 7,7-F2, 10,10,10-F3, and 7,7,8,8-F4 analogs did not differ significantly from that of the natural three-component mixture and the two-component mixture, whereas the mixture containing F9 elicited a significantly lower male response, as low as the response to the two-component mixture. In a field test the mixtures containing 10,10,10-F3 and 7,7,8,8-F4 were significantly more active than the two-component mixture, but still less active than the natural three-component mixture. It appears that field tests provided greater discrimination among pheromone analogs in assessing their behavioral activity than the flight-tunnel test did. Structure-activity analyses demonstrate the importance of the lipophilic interaction between the terminal alkyl chain and the receptor site for the activity of the stimulus. The lipophobicity of the fluorinated analogs impedes a productive receptor interaction.
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