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- de Jong, Roelof S., et al.
(författare)
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4MOST-4-metre Multi-Object Spectroscopic Telescope
- 2014
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Ingår i: Ground-based and Airborne Instrumentation for Astronomy V. - : SPIE. - 0277-786X .- 1996-756X. ; 9147
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Konferensbidrag (refereegranskat)abstract
- 4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO and from ground-based facilities like VISTA, VST, DES, LSST and SKA. The 4MOST baseline concept features a 2.5 degree diameter field-of-view with similar to 2400 fibres in the focal surface that are configured by a fibre positioner based on the tilting spine principle. The fibres feed two types of spectrographs; similar to 1600 fibres go to two spectrographs with resolution R> 5000 (lambda similar to 390-930 nm) and similar to 800 fibres to a spectrograph with R> 18,000 (lambda similar to 392-437 nm & 515-572 nm & 605-675 nm). Both types of spectrographs are fixed-configuration, three-channel spectrographs. 4MOST will have an unique operations concept in which 5 year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the southern sky. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept. 4MOST has been accepted for implementation by ESO with operations expected to start by the end of 2020. This paper provides a top-level overview of the 4MOST facility, while other papers in these proceedings provide more detailed descriptions of the instrument concept[1], the instrument requirements development[2], the systems engineering implementation[3], the instrument model[4], the fibre positioner concepts[5], the fibre feed[6], and the spectrographs[7].
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- De Jong, Roelof S., et al.
(författare)
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4MOST : The 4-metre Multi-Object Spectroscopic Telescope project at preliminary design review
- 2016
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Ingår i: Ground-Based and Airborne Instrumentation for Astronomy VI. - : SPIE. - 1996-756X .- 0277-786X. - 9781510601956 ; 9908
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Konferensbidrag (refereegranskat)abstract
- We present an overview of the 4MOST project at the Preliminary Design Review. 4MOST is a major new wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of ESO. 4MOST has a broad range of science goals ranging from Galactic Archaeology and stellar physics to the high-energy physics, galaxy evolution, and cosmology. Starting in 2021, 4MOST will deploy 2436 fibres in a 4.1 square degree field-of-view using a positioner based on the tilting spine principle. The fibres will feed one high-resolution (R∼20,000) and two medium resolution (R∼5000) spectrographs with fixed 3-channel designs and identical 6k x 6k CCD detectors. 4MOST will have a unique operations concept in which 5-year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept, showing that we can expect to observe more than 25 million objects in each 5-year survey period and will eventually be used to plan and conduct the actual survey.
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- Hamngren Blomqvist, Charlotte, 1984, et al.
(författare)
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Design and evaluation of a microfluidic system for inhibition studies of yeast cell signaling
- 2012
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Ingår i: Proceedings of SPIE. - : SPIE. - 0277-786X .- 1996-756X. - 9780819491756 ; , s. 84582K-
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Konferensbidrag (refereegranskat)abstract
- In cell signaling, different perturbations lead to different responses and using traditional biological techniques that result in averaged data may obscure important cell-to-cell variations. The aim of this study was to develop and evaluate a four-inlet microfluidic system that enables single-cell analysis by investigating the effect on Hog1 localization post a selective Hog1 inhibitor treatment during osmotic stress. Optical tweezers was used to position yeast cells in an array of desired size and density inside the microfluidic system. By changing the flow rates through the inlet channels, controlled and rapid introduction of two different perturbations over the cell array was enabled. The placement of the cells was determined by diffusion rates flow simulations. The system was evaluated by monitoring the subcellular localization of a fluorescently tagged kinase of the yeast "High Osmolarity Glycerol" (HOG) pathway, Hog1-GFP. By sequential treatment of the yeast cells with a selective Hog1 kinase inhibitor and sorbitol, the subcellular localization of Hog1-GFP was analysed on a single-cell level. The results showed impaired Hog1-GFP nuclear localization, providing evidence of a congenial design. The setup made it possible to remove and add an agent within 2 seconds, which is valuable for investigating the dynamic signal transduction pathways and cannot be done using traditional methods. We are confident that the features of the four-inlet microfluidic system will be a valuable tool and hence contribute significantly to unravel the mechanisms of the HOG pathway and similar dynamic signal transduction pathways.
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- Löfstrand, Anette, et al.
(författare)
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Sequential infiltration synthesis and pattern transfer using 6 nm half-pitch carbohydrate-based fingerprint block copolymer
- 2021
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Ingår i: Advances in Patterning Materials and Processes XXXVIII. - : SPIE. - 1996-756X .- 0277-786X. - 9781510640573 - 9781510640580 ; 11612
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Konferensbidrag (refereegranskat)abstract
- This study presents how sequential infiltration synthesis of trimethyl aluminium and water into a carbohydrate-based block copolymer was used to enable pattern transfer of 6 nm half-pitch horizontal cylinders into silicon. Specular neutron reflectometry measurements of poly(styrene)-block-maltoheptaose self-assembled into horizontal cylinders indicate an increasing content of alumina after each sequential infiltration cycle, comparing 0, 1, 2, and 4 cycles, with alumina content reaching 2.4 vol% after four infiltrations cycles. Dry etching processes in inductively coupled plasma reactive ion etching for sub-10 nm patterns were developed, using a two-step technique: O2-plasma for polymer removal and a reactive ion etching of Si using a mixture of SF6 and C4F8 gases. Etch selectivity of more than 2:1 of silicon over alumina-like etch mask material was achieved. To evaluate the etching process, the etched Si structures were measured and characterized by scanning electron microscopy. These results are expected to be of use for nanofabrication and applications in the sub-10 nm regime.
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- Paladini, C., et al.
(författare)
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To be or not to be asymmetric? VLTI and the mass loss geometry of red giants
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819491466 ; 8445, s. Art. no. 84451R-
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Konferensbidrag (refereegranskat)abstract
- The mass-loss process is a key ingredient for our understanding in many fields of astrophysics, including stellar evolution and the enrichment of the interstellar medium (ISM) via stellar yields. We combined the capability of the VLTI/MIDI and VLT/VISIR instruments with very recent Herschel/PACS observations to characterize the geometry of mass loss from evolved red giants on the Asymptotic Giant Branch (AGB) at various scales. This paper describes the sample of objects, the observing strategy, the tool for the interpretation, and preliminary MIDI results for two targets: U Ant and θ Aps.
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| 9. |
- Söderberg, Per G, et al.
(författare)
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Evaluation of response variables in computer simulated virtual reality cataract surgery
- 2006
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - San José, CA : SPIE. - 0277-786X .- 1996-756X. ; 6138, s. 131-139
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a virtual reality (VR) simulator for phacoemulsification (phaco) surgery. The current work aimed atevaluating the precision in the estimation of response variables identified for measurement of the performance of VRphaco surgery. We identified 31 response variables measuring; the overall procedure, the foot pedal technique, thephacoemulsification technique, erroneous manipulation, and damage to ocular structures. Totally, 8 medical oroptometry students with a good knowledge of ocular anatomy and physiology but naive to cataract surgery performedthree sessions each of VR Phaco surgery. For measurement, the surgical procedure was divided into a sculpting phaseand an evacuation phase. The 31 response variables were measured for each phase in all three sessions. The variancecomponents for individuals and iterations of sessions within individuals were estimated with an analysis of varianceassuming a hierarchal model. The consequences of estimated variabilities for sample size requirements weredetermined. It was found that generally there was more variability for iterated sessions within individuals formeasurements of the sculpting phase than for measurements of the evacuation phase. This resulted in larger requiredsample sizes for detection of difference between independent groups or change within group, for the sculpting phase ascompared to for the evacuation phase. It is concluded that several of the identified response variables can be measuredwith sufficient precision for evaluation of VR phaco surgery.
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| 10. |
- Söderberg, Per G, et al.
(författare)
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Measuring performance in virtual relaity phacoemulsification surgery
- 2008
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - San José, CA : SPIE. - 0277-786X .- 1996-756X. ; 6844, s. 13:1-13:9
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a virtual reality (VR) simulator for phacoemulsification surgery. The current work aimed atdeveloping a relative performance index that characterizes the performance of an individual trainee. We recordedmeasurements of 28 response variables during three iterated surgical sessions in 9 experienced cataract surgeons,separately for the sculpting phase and the evacuation phase of phacoemulsification surgery and compared their outcometo that of a reference group of naive trainees. We defined an individual overall performance index, an individual classspecific performance index and an individual variable specific performance index. We found that on an average theexperienced surgeons performed at a lower level than a reference group of naive trainees but that this was particularlyattributed to a few surgeons. When their overall performance index was further analyzed as class specific performanceindex and variable specific performance index it was found that the low level performance was attributed to a behaviorthat is acceptable for an experienced surgeon but not for a naive trainee. It was concluded that relative performanceindices should use a reference group that corresponds to the measured individual since the definition of optimal surgerymay vary among trainee groups depending on their level of experience.
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