| 1. |
- Marinucci, A., et al.
(författare)
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Polarization constraints on the X-ray corona in Seyfert Galaxies : MCG-05-23-16
- 2022
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 516:4, s. 5907-5913
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first observation of a radio-quiet active galactic nucleus (AGN) in polarized X-rays: the Seyfert 1.9 galaxy MCG-05-23-16. This source was pointed at with the Imaging X-ray Polarimetry Explorer (IXPE) starting on 2022 May 14 for a net observing time of 486 ks, simultaneously with XMM-Newton (58 ks) and NuSTAR (83 ks). A polarization degree Π smaller than 4.7 per cent (at the 99 per cent confidence level) is derived in the 2–8 keV energy range, where emission is dominated by the primary component ascribed to the hot corona. The broad-band spectrum, inferred from a simultaneous fit to the IXPE, NuSTAR, and XMM-Newton data, is well reproduced by a power law with photon index Γ = 1.85 ± 0.01 and a high-energy cutoff EC = 120 ± 15 keV. A comparison with Monte Carlo simulations shows that a lamp-post and a conical geometry of the corona are consistent with the observed upper limit, a slab geometry is allowed only if the inclination angle of the system is less than 50°.
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| 2. |
- Habiba, M, et al.
(författare)
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Caesarean section on request: a comparison of obstetricians' attitudes in eight European countries
- 2006
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Ingår i: BJOG: An International Journal of Obstetrics & Gynaecology. - : Wiley. - 1471-0528 .- 1470-0328. ; 113:6, s. 647-656
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Tidskriftsartikel (refereegranskat)abstract
- Objective To explore the attitudes of obstetricians to performe a caesarean section on maternal request in the absence of medical indication. Design Cluster sampling cross-sectional survey. Setting Neonatal Intensive Care Unit (NICU) associated maternity units in eight European countries. Population Obstetricians with at least 6 months clinical experience. Methods NICU-associated maternity units were chosen by census in Luxembourg, Netherlands and Sweden and by geographically stratified random sampling in France, Germany, Italy, Spain and UK. An anonymous, self-administered questionnaire was used for data collection. Main outcome measures Obstetricians' willingness to perform a caesarean section on maternal request. Results One hundred and five units and 1530 obstetricians participated in the study (response rates of 70 and 77%,respectively). Compliance with a hypothetical woman's request for elective caesarean section simply because it was 'her choice' was lowest in Spain (15%), France (19%) and Netherlands (22%); highest in Germany (75%) and UK (79%) and intermediate in the remaining countries. Using weighted multivariate logistic regression, country of practice (P < 0.001), fear of litigation (P = 0.004) and working in a university-affiliated hospital (P = 0.001) were associated with physicians' likelihood to agree to patient's request. The subset of female doctors with children was less likely to agree (OR 0.29, 95% CI 0.20-0.42). Conclusions The differences in obstetricians' attitudes are not founded on concrete medical evidence. Cultural factors, legal liability and variables linked to the specific perinatal care organisation of the various countries play a role. Greater emphasis should be placed on understanding the motivation, values and fears underlying a woman's request for elective caesarean delivery.
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| 3. |
- Habiba, M., et al.
(författare)
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Late termination of pregnancy: a comparison of obstetricians' experience in eight European countries
- 2009
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Ingår i: BJOG: An International Journal of Obstetrics & Gynaecology. - : Wiley. - 1471-0528 .- 1470-0328. ; 116:10, s. 1340-1349
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Tidskriftsartikel (refereegranskat)abstract
- Objective To compare the experience and attitude of obstetricians in Europe towards late termination of pregnancy and the factors affecting their responses. Design Cluster sampling cross-sectional survey. All neonatal intensive care unit (NICU)-associated maternity units were recruited (census sampling) in Luxembourg, the Netherlands and Sweden. In France, Germany, Italy, Spain and the UK, units were selected at random. In every recruited unit, all obstetricians with at least 6 months' experience were invited to participate. Setting NICU-associated maternity units in eight European countries. Population Obstetricians with at least 6 months' clinical experience. Methods An anonymous, self-administered questionnaire was used. Multinomial logistic analysis was used to identify factors predicting the obstetricians' views about modifying the law governing late termination in their country. Main outcome measure Obstetricians' experience of late termination of pregnancy and views about national policies. Results One hundred and five units and 1530 obstetricians participated (response rates 70 and 77% respectively). The most common indications for late termination were congenital anomalies and women's physical health. Feticide was not common except in France, Luxembourg and the UK. Active euthanasia of a liveborn was practiced in France and the Netherlands. Obstetricians in Germany were more likely to feel that late termination should be more severely restricted, the opposite was true in Spain and the Netherlands. In Italy, there was dissatisfaction with current status, but opinion was divided, reflecting views on both sides of the debate. Conclusions This research outlines current practice in a difficult and sensitive area and suggests the need for more discussion and support for all those who were involved.
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| 4. |
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| 5. |
- Heyl, C. M., et al.
(författare)
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Noncollinear optical gating - A method for intra-cavity single attosecond pulse generation?
- 2019
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Ingår i: Proceedings 2015 European Conference on Lasers and Electro-Optics - European Quantum Electronics Conference, CLEO/Europe-EQEC 2015. - 9781467374750
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Konferensbidrag (refereegranskat)abstract
- The process of high-order harmonic generation requires laser intensities around 1014 W/cm2, most easily reached with laser pulses of high energy, thus implicitly limiting the repetition rate of attosecond sources. A route towards multi-MHz attosecond sources relies on HHG inside a passive enhancement cavity [1]. Although successfully demonstrated for attosecond pulse trains, the generation of single attosecond pulses (SAPs) inside a cavity remains an unsolved challenge, mainly limited by dispersion management and out-coupling problems. We recently proposed a new gating concept for SAP generation [2], noncollinear optical gating (NOG) which has the potential to facilitate SAP gating and efficient out-coupling at once. Similar to the recently introduced attosecond lighthouse [3] NOG employs attosecond angular streaking [4] and combines this concept with noncollinear HHG, proposed earlier [5] as out-coupling method for intra cavity HHG.
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| 6. |
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| 7. |
- Lorek, Eleonora, et al.
(författare)
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High-Order Harmonic Generation and Plasmonics
- 2015
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Ingår i: Nano-Structures for Optics and Photonics : Optical Strategies for Enhancing Sensing, Imaging, Communication and Energy Conversion - Optical Strategies for Enhancing Sensing, Imaging, Communication and Energy Conversion. - Dordrecht : Springer Netherlands. - 9789401791328 - 9789401791335 ; , s. 531-531
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Bokkapitel (refereegranskat)abstract
- Attosecond pulses allow for imaging of very fast processes, like electron dynamics. Stockman et al. suggested to use these pulses in connection with a Photoemission electron microscope (PEEM) to study the ultrafast dynamics of plasmons (Stockman et al. Nat Photonics 1:539–544, 2007). For efficient plasmon studies, the repetition rate of the attosecond pulses used needs to be higher than a few kHz (Mikkelsen et al. Rev Sci Instrum 80:123703, 2009). Attosecond pulses are produced in a process called high-order harmonic generation (HHG) (Paul et al. Science 292(5522):1689–1692, 2001; Ferray et al. J Phys B At Mol Opt Phys 21:L31–L35, 1988). In HHG, a strong laser field allows an electron to tunnel out, get accelerated and recombine with a high kinetic energy resulting in extreme ultraviolet attosecond pulses. The large intensity needed to drive the process normally limits the repetition rate of the laser to a few kHz. Using a tight focusing scheme (Heyl et al. Phys Rev Lett 107:033903, 2011; Vernaleken et al. Opt Lett 36:3428–3430, 2011), we, however, generate harmonics at a repetition rate of 200 kHz, both with a commercial turn-key laser and with an advanced laser system. Suitable nanostructures for a strong field enhancement are produced in-house and the field enhancement is studied with PEEM in a non-time resolved manner. With high-order harmonics produced at a high repetition rate, we hope to be able to follow also the ultrafast dynamics of plasmons in these structures (Mårsell et al. Ann der Phys 525:162–170, 2013).
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