| 1. |
- Pastorello, A., et al.
(author)
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INTERACTING SUPERNOVAE AND SUPERNOVA IMPOSTORS : SN 2009ip, IS THIS THE END?
- 2013
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 767:1, s. 1-
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Journal article (peer-reviewed)abstract
- We report the results of a three-year-long dedicated monitoring campaign of a restless luminous blue variable (LBV) in NGC 7259. The object, named SN 2009ip, was observed photometrically and spectroscopically in the optical and near-infrared domains. We monitored a number of erupting episodes in the past few years, and increased the density of our observations during eruptive episodes. In this paper, we present the full historical data set from 2009 to 2012 with multi-wavelength dense coverage of the two high-luminosity events between 2012 August and September. We construct bolometric light curves and measure the total luminosities of these eruptive or explosive events. We label them the 2012a event (lasting similar to 50 days) with a peak of 3x10(41) erg s(-1), and the 2012b event (14 day rise time, still ongoing) with a peak of 8 x 1042 erg s(-1). The latter event reached an absolute R-band magnitude of about -18, comparable to that of a core-collapse supernova (SN). Our historical monitoring has detected high-velocity spectral features (similar to 13,000 km s(-1)) in 2011 September, one year before the current SN-like event. This implies that the detection of such high-velocity outflows cannot, conclusively, point to a core-collapse SN origin. We suggest that the initial peak in the 2012a event was unlikely to be due to a faint core-collapse SN. We propose that the high intrinsic luminosity of the latest peak, the variability history of SN 2009ip, and the detection of broad spectral lines indicative of high-velocity ejecta are consistent with a pulsational pair-instability event, and that the star may have survived the last outburst. The question of the survival of the LBV progenitor star and its future fate remain open issues, only to be answered with future monitoring of this historically unique explosion.
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| 2. |
- Ivarson, Anders, et al.
(author)
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Oxidation dynamics of laser cutting of mild steel and the generation of striations on the cut edge
- 1994
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In: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 40:3-4, s. 359-374
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Journal article (peer-reviewed)abstract
- Over the past two decades CO2 laser cutting has grown from an obscure laboratory technique into an important branch of manufacturing engineering. The most commonly cut materials are steels and a great deal of industrial and scientific research has been carried out on the laser-material interactions that generate a cut. This paper concentrates on the phenomena which give rise to a cyclic cutting event when a CO2 laser in conjunction with an oxygen jet is used to cut mild steel. The nature of the cut edge striation produced by the cyclic oxidation reaction is explained thoroughly and a possible oxidation cycle is postulated. It is demonstrated that the key to understanding the cyclic nature of the cutting event is the self-limiting nature of the oxidation of the steel in the cut zone
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| 3. |
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| 4. |
- Knez, Rajna, 1969, et al.
(author)
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Medical residents' and teachers' perceptions of the digital format of nation-wide didactic courses for psychiatry residents in Sweden: a survey-based observational study
- 2023
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In: Bmc Medical Education. - : Springer Science and Business Media LLC. - 1472-6920. ; 23:1
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Journal article (peer-reviewed)abstract
- Background : This study aimed to explore residents' and teachers' perceptions of the digital format of Metis (a national education network in Sweden) didactic courses for psychiatry residents in Sweden to guide post-pandemic curriculum development.Methods : An online attitude survey was developed and sent out to 725 residents in psychiatry and 237 course directors/teachers. Data were examined descriptively and group differences were analysed with independent sample t-tests.Results : The survey was completed by 112 residents and 72 course directors/teachers. Perceptions of digital formats were quite similar between the two groups with some significant differences i.e., residents agreed more strongly than directors/teachers with the statement that Metis courses in digital format were of the same quality (or better) than the classroom-based format. Residents perceived the positive effects of using interactive tools more than directors/teachers. More than 40% of the responders in both groups preferred a return to classroom-based course meetings. Responders in both groups suggested that different forms of digital elements (e.g., video-based and sound-recorded lectures, digital-group discussions, virtual patients) could be incorporated into different phases in the courses.Conclusions : The study represents the current largest survey among residents in psychiatry and a teaching faculty in Sweden, to understand the impact of digitalization on the quality of residents' education during the pandemic. The results point towards applying a mixed format for training and education going forward, incorporating digital aspects into the national curriculum.
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| 5. |
- Powell, John, et al.
(author)
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International congress on applications of lasers and electro-opticsd
- 1992
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In: Proceedings of the laser materials processing symposium, ICALEO '92. - Orlando, Fla. : Laser institute of America. - 0912035498 ; , s. 433-442
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Conference paper (peer-reviewed)abstract
- This paper begins by describing the thermal inputs to the cut zone when cutting mild steel with oxygen as the assist gas. The investigation concentrates on the chemical thermo-dynamics in the cut zone and pays particular attention to the influence of oxygen dilution. A detailed experimental program has allowed the authors to theoretically clarify why the process is highly sensitive to small levels of contamination of the oxygen jet.
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| 6. |
- Powell, John, et al.
(author)
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Role of oxygen purity in laser cutting of mild steel
- 1992
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In: Proceedings of the laser materials processing symposium, ICALEO '92. - Orlando, fla : Laser institute of America. - 0912035498 ; , s. 433-442
-
Conference paper (peer-reviewed)abstract
- This paper begins by describing the thermal inputs to the cut zone when cutting mild steel with oxygen as the assist gas. The investigation concentrates on the chemical thermo-dynamics in the cut zone and pays particular attention to the influence of oxygen dilution. A detailed experimental program has allowed the authors to theoretically clarify why the process is highly sensitive to small levels of contamination of the oxygen jet.
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