| 11. |
- Antoine, P, et al.
(författare)
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Polarization of high-order harmonics
- 1997
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 55:2, s. 1314-1324
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Tidskriftsartikel (refereegranskat)abstract
- We report measurements and calculations of the polarization state of high-order harmonics generated by a 790-nm Ti:sapphire laser. The problem of completely characterizing the polarization state of a partially polarized radiation in the XUV range is discussed in detail. The comparison between several gases, xenon, argon and neon, and different orders, from the 17th to the 33rd, shows that the rotation angle and ellipticity strongly depends on the position of the harmonic in the spectrum, and in particular, whether it is in the cutoff or in the plateau. In the plateau, the rotation angle is quite large, and the ellipticity follows that of the fundamental, remaining, however, smaller. The radiation is only partially polarized. In contrast, in the cutoff, both rotation angle and ellipticity remain small, independently of the laser ellipticity. Our experimental results compare well with theoretical predictions including the single-atom response and propagation effects.
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| 12. |
- Antoine, P, et al.
(författare)
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Theory of high-order harmonic generation by an elliptically polarized laser field
- 1996
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 53:3, s. 1725-1745
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Tidskriftsartikel (refereegranskat)abstract
- We generalize a recently formulated theory of high-order harmonic generation by low-frequency laser fields [Anne L'Huillier et al., Phys. Rev. A 48, R3433 (1993)] to the case of an elliptically polarized light. Our theoretical description includes both the single-atom response and propagation. Phase matching significantly modifies the results obtained in the single-atom response. The results of our calculations, including propagation for both the intensity and polarization properties of harmonics as a function of laser ellipticity, compare very well with recent experimental observations.
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| 13. |
- Costello Daly, C, et al.
(författare)
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Validation of the WHO diagnostic algorithm and development of an alternative scoring system for the management of women presenting with vaginal discharge in Malawi
- 1998
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Ingår i: Sexually Transmitted Infections. - : BMJ Publishing Group Ltd. - 1368-4973 .- 1472-3263. ; 74:Suppl 1, s. S50-S58
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the performance of the WHO algorithm for the detection of cervical infection in women presenting with vaginal discharge and modify the risk assessment score for optimum effectiveness in Malawi.METHODS: 550 consecutive women presenting with non-ulcerative genitourinary complaints were interviewed and examined. Cervical infection was defined as presence of Neisseria gonorrhoeae on culture and/or Chlamydia trachomatis by EIA. Other laboratory investigations included wet mount microscopy, serology for syphilis and HIV, LED testing of cervical and vaginal secretions, and pH testing of vaginal fluid. Sensitivity, specificity, and positive predictive values (PPV) of different algorithms were determined in the analysis.RESULTS: Cervical infection was identified in 19.5% of women (17.1% gonorrhoea, 3.7% chlamydial infection). The sensitivity/specificity/PPV of the WHO risk assessment were 43%/73%/28%, respectively by history and 62%/61%/27% with the addition of speculum examination. Using Malawi results to modify the risk assessment improved the performance to 61%/68%/31% respectively by history alone, which increased to 73%/64%/33% with bimanual examination and 72%/56%/29% with speculum examination.CONCLUSION: The sensitivity of the WHO risk assessment is low for the detection of cervical infection in Malawi. Although the Malawi risk assessment performed somewhat better on history alone, this study identified external and bimanual examination variables that improved the diagnostic performance of the algorithm in settings where speculum examination is not possible. Although the PPVs of the algorithms are low, country specific risk assessments can provide a framework for management until simple, affordable diagnostic tests for the definitive diagnosis of cervical infection are available.
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| 14. |
- Dallabetta, G, et al.
(författare)
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Specificity of dysuria and discharge complaints and presence of urethritis in male patients attending an STD clinic in Malawi
- 1998
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Ingår i: Sexually Transmitted Infections. - : BMJ Publishing Group Ltd. - 1368-4973 .- 1472-3263. ; 74:Suppl 1, s. S34-S37
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: This study evaluated the specificity of discharge and dysuria for laboratory confirmed urethritis in symptomatic men presenting to an urban STD clinic in Malawi for treatment and returning for follow up evaluation.METHODS: Clinical treatment trial where consecutive consenting men with urethritis were enrolled and administered a questionnaire, examined, tested, and given one of five urethritis treatments with an efficacy range of 33-95%. Men returning for follow up were questioned, examined, and tested.RESULTS: The presence of both discharge and dysuria were highly specific for laboratory confirmed urethritis (over 90%). Compared with men who had complaints of both discharge and dysuria, men with complaints of dysuria alone were more likely to have reported prior treatment, 72% v 48% (p = 0.003), and less likely to have had gonorrhoea, 64% v 83% (p = 0.04). Men with complaints of discharge or dysuria without evidence of discharge were rare but half of them had documented urethritis. Among men who returned for follow up, 72% had no symptoms of either discharge or dysuria. However, among the 238 men with no symptoms at follow up, laboratory documented gonorrhoea occurred in 9% and non-gonococcal urethritis in 21%.DISCUSSION: In this population of men discharge or dysuria were specific symptoms for urethritis. The symptom of dysuria should be added as an entry criterion for evaluation for urethritis in the World Health Organisation's treatment recommendations. The high prevalence of asymptomatic infection at follow up in a population of men who received suboptimal antimicrobial therapy suggests that the most effective therapy available should be given at the first visit.
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| 15. |
- Eriksson, B. K., et al.
(författare)
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Liver embolizations of patients with malignant neuroendocrine gastrointestinal tumors
- 1998
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Ingår i: Cancer. - 0008-543X .- 1097-0142. ; 83:11, s. 2293-2301
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND Patients with neuroendocrine gastrointestinal tumors usually present with inoperable metastatic disease and severe hormonal symptoms. Specific chemotherapy, interferon-alpha (IFN), and somatostatin analogs are established therapies for these patients, but all of them eventually fail. Hepatic arterial embolization can provide reduction of both hormonal symptoms and tumor burden in these patients. METHODS Between 1981 and 1995, a total of 55 liver embolizations with gel foam powder were performed on 41 patients with histopathologically verified neuroendocrine tumors; 29 had carcinoid tumors and 12 had endocrine pancreatic tumors (EPTs). All patients had received medical treatment, including chemotherapy (n = 18), IFN (n = 31), and octreotide (n = 19), and were experiencing treatment failure when liver embolization was performed at a median of 37 months after diagnosis of liver metastases. Medical treatment was continued after embolization. RESULTS An overall objective response was noted in 15 of 29 patients with carcinoid tumors (52%). The median duration of effect was 12 months in patients with midgut carcinoid tumors. An overall objective response was observed in 6 of 12 patients with EPTs (50%), with a median duration of effect of 10 months. Adverse events were observed, and, in agreement with earlier reports, the rate of serious complications was 10%. Survival analyses showed a median survival of 80 months and a 5-year survival rate of 60% from the performance of embolization on patients with midgut carcinoid tumors, whereas for patients with EPTs the median survival from embolization was only 20 months. CONCLUSIONS Liver embolizations performed relatively late in the clinical course in our series appeared to be as effective as "early" embolizations in other series of patients with carcinoid tumors. The results for those with EPTs were poorer, and earlier embolizations may result in better outcomes for these patients. Considering the morbidity associated with the procedure, it is imperative to select patients according to extent of liver involvement, severity of carcinoid heart disease, and somatostatin receptor status.
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| 16. |
- Gaarde, Mette, et al.
(författare)
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Theory of high-order sum and difference frequency mixing in a strong bichromatic laser field
- 1996
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 54:5, s. 4236-4248
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Tidskriftsartikel (refereegranskat)abstract
- We generalize the recently formulated theory of high-order harmonic generation by low-frequency laser fields to the case of high-order sum and difference frequency mixing in a two-color field of noncommensurate frequencies in the optical-infrared regime. Our theoretical description includes both the single-atom response and propagation. We observe a different behavior of the sum and difference frequency mixing processes, in the single-atom response as well as in the propagation results. The results of our calculations including propagation compare very well with recent experimental observations.
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| 17. |
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| 18. |
- Lewenstein, M, et al.
(författare)
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Phase of the Atomic Polarization In High-order Harmonic-generation
- 1995
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 52:6, s. 4747-4754
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Tidskriftsartikel (refereegranskat)abstract
- A recently formulated theory of high-order harmonic generation by low-frequency laser fields [Anne L'Huillier et al., Phys. Rev. A 48, R3433 (1993)] allows us to study the phase of the induced atomic dipole moment. We show that this phase exhibits a piecewise-linear dependence on the laser intensity. This dependence can be interpreted in quasiclassical terms, and is related to the action acquired by the electron during its motion in the laser held. The value of the phase, however, is also affected by the quantum effects of tunneling, diffusion, and interference. The phase of the dipole moment considerably influences the conversion efficiency, as well as the coherence properties, of the harmonics generated in macroscopic media.
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| 19. |
- Lynga, C, et al.
(författare)
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Temporal coherence of high-order harmonics
- 1999
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 60:6, s. 4823-4830
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Tidskriftsartikel (refereegranskat)abstract
- Systematic studies of the temporal coherence properties of high-order harmonic radiation are presented. These complement our previous investigations [Bellini et at, Phys. Rev. Lett. 81, 297 (1998)], where we showed the separation of the far-field pattern of high-order harmonics into two distinct spatial regions with different coherence times. Here we show how the coherence time of the inner and outer regions changes as a function of the harmonic order, the laser intensity, and the focusing conditions. Good agreement with the predictions of the semiclassical model of harmonic generation is obtained. [S1050-2947(99)10312-3].
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| 20. |
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