| 1. |
- Fomalont, E. B., et al.
(författare)
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THE 2014 ALMA LONG BASELINE CAMPAIGN: AN OVERVIEW
- 2015
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 808:1
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Tidskriftsartikel (refereegranskat)abstract
- A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to similar to 15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from 2014 September to late November, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at similar to 350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.
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| 2. |
- Wilke, T., et al.
(författare)
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Deep drilling reveals massive shifts in evolutionary dynamics after formation of ancient ecosystem
- 2020
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 6:40
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Tidskriftsartikel (refereegranskat)abstract
- The scarcity of high-resolution empirical data directly tracking diversity over time limits our understanding of speciation and extinction dynamics and the drivers of rate changes. Here, we analyze a continuous species-level fossil record of endemic diatoms from ancient Lake Ohrid, along with environmental and climate indicator time series since lake formation 1.36 million years (Ma) ago. We show that speciation and extinction rates nearly simultaneously decreased in the environmentally dynamic phase after ecosystem formation and stabilized after deep-water conditions established in Lake Ohrid. As the lake deepens, we also see a switch in the macroevolutionary trade-off, resulting in a transition from a volatile assemblage of short-lived endemic species to a stable community of long- lived species. Our results emphasize the importance of the interplay between environmental/climate change, ecosystem stability, and environmental limits to diversity for diversification processes. The study also provides a new understanding of evolutionary dynamics in long-lived ecosystems.
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| 3. |
- Asaki, Yoshiharu, et al.
(författare)
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ALMA High-frequency Long Baseline Campaign in 2021 : Highest Angular Resolution Submillimeter Wave Images for the Carbon-rich Star R Lep
- 2023
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Ingår i: Astrophysical Journal. - : Institute of Physics (IOP). - 0004-637X .- 1538-4357. ; 958:1
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Tidskriftsartikel (refereegranskat)abstract
- The Atacama Large Millimeter/submillimeter Array (ALMA) was used in 2021 to image the carbon-rich evolved star R Lep in Bands 8-10 (397-908 GHz) with baselines up to 16 km. The goal was to validate the calibration, using band-to-band (B2B) phase referencing with a close phase calibrator J0504-1512, 1.degrees 2 from R Lep in this case, and the imaging procedures required to obtain the maximum angular resolution achievable with ALMA. Images of the continuum emission and the hydrogen cyanide (HCN) maser line at 890.8 GHz, from the J = 10-9 transition between the (1110) and (0400) vibrationally excited states, achieved angular resolutions of 13, 6, and 5 mas in Bands 8-10, respectively. Self-calibration (self-cal) was used to produce ideal images to compare with the B2B phase referencing technique. The continuum emission was resolved in Bands 9 and 10, leaving too little flux for the self-cal of the longest baselines, so these comparisons are made at coarser resolution. Comparisons showed that B2B phase referencing provided phase corrections sufficient to recover 92%, 83%, and 77% of the ideal image continuum flux densities. The HCN maser was sufficiently compact to obtain self-cal solutions in Band 10 for all baselines (up to 16 km). In Band 10, B2B phase referencing as compared to the ideal images recovered 61% and 70% of the flux density for the HCN maser and continuum, respectively.
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| 4. |
- AYASSE, M, et al.
(författare)
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ARE THERE PHEROMONAL DOMINANCE SIGNALS IN THE BUMBLEBEE BOMBUS-HYPNORUM L (HYMENOPTERA, APIDAE)
- 1995
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Ingår i: APIDOLOGIE. - : EDITIONS SCIENTIFIQUES ELSEVIER. - 0044-8435. ; 26:3, s. 163-180
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In the bumblebee Bombus hypnorum (Apidae) 132 chemical compounds could be identified by GC/MS and coinjection. The behavior of individual workers was observed to characterize them as dominant, subordinate or foragers. Queens, dominance groups of workers a
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| 5. |
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| 6. |
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| 7. |
- Tengo, J., et al.
(författare)
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(S)-(+)-linalool, a mate attractant pheromone component in the bee Colletes cunicularius
- 2003
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Ingår i: Journal of Chemical Ecology. - : Springer. - 0098-0331 .- 1573-1561. ; 29:1, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Enantiomerically pure (S)-(+)- linalool was the main constituent in the extracts of the cephalic secretions of virgin females, mated females, freshly emerged males, and patrolling males of the solitary bee Colletes cunicularius. After copulation, the content of (S)-(+)- linalool emitted by the female was strongly reduced. Electrophysiological experiments revealed that both enantiomers of linalool elicited responses from the antennae of the males. Field tests using the pure enantiomers and the racemate of linalool showed that the number of male bees attracted was highest for (S)-(+)- linalool. The search flight activity in the mating flight area increased dramatically when patrolling males were presented with (S)-(+)- linalool vs (R)-(+)- linalool. Taken together, these data indicate a mate attractant pheromone function of (S)-(+)- linalool.
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| 8. |
- Thunberg, S., et al.
(författare)
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Dose reduction in mammography with photon counting imaging
- 2004
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. ; , s. 457-465
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Konferensbidrag (refereegranskat)abstract
- The purpose of this study was to investigate if the glandular dose to the breast in mammography can significantly be reduced without compromising image quality, when using photon counting technology, in a multi-slit scanning photon counting detector, compared to a conventional film mammography system and commercial available digital mammography systems with TFT-array detectors. A CDMAM phantom study, with two different thicknesses of additional PMMA absorber, 4 cm and 7 cm respectively, has shown that multi-slit scanning photon counting detector technology can reduce the dose, without reducing the image quality. This comparison was made to two commercial available digital mammography systems Senographe 2000D (from GEMS) and Selenia (from Lorad). The results show that dose can be reduced with 63% to 77%, depending on object thickness, when using XCT for mammography. This dose reduction has also been verified clinically through a small pilot study with patients and specimen, where the comparison was made between XCT and film.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Baker, T. C., et al.
(författare)
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Identification and bioassay of sex pheromone components of carob moth, Ectomyelois ceratoniae (Zeller)
- 1991
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Ingår i: Journal of Chemical Ecology. - 0098-0331. ; 17:10, s. 1973-1988
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Tidskriftsartikel (refereegranskat)abstract
- Three sex pheromone components of the carob moth were isolated and identified from the extract of female pheromone glands, using a variety of techniques including coupled gas chromatographic-electroantennographic recordings, coupled gas chromatographic-mass spectrometric analysis, microozonolysis, electroantennographic assays of monounsaturated standards, wind-tunnel bioassays, and field trials. The major component was identified as (Z,E)-9,11,13-tetradecatrienal, a novel lepidopterous pheromone component structure. Two minor components, either one of which improves the upwind flight response of males when blended with the major component, were identified as (Z,E)-9,11-tetradecadienal, and (Z)-9-tetra-decenal.
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| 13. |
- Baker, T. C., et al.
(författare)
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Isolation, identification and synthesis of sex pheromone components of the carob moth, Ectomyelois ceratoniae
- 1989
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Ingår i: Tetrahedron Letters. - 0040-4039. ; 30:22, s. 2901-2902
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Tidskriftsartikel (refereegranskat)abstract
- The sex pheromone of females of the carob moth, Ectomyelois ceratoniae, was identified to be a mixture of (Z,E)-9,11,13-tetradecatrienal, (Z,E)-9,11-tetradecadienal and (Z)-9-tetradecenal in the ratio of 10:1:1. A synthetic blend proved to be attractive. GC/EAD + GC/MS investigations showed (Z,E)-9,11,13-tetradecatrienal, (Z,E)-9,11-tetradecadienal and (Z)-9-tetradecenal to be the sex pheromone of the carob moth. Blends of synthetic compounds are active.
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| 14. |
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| 16. |
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| 17. |
- Carlson, P., et al.
(författare)
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Beyond the RICH : innovative photosensitive gaseous detectors for new fields of applications
- 2003
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 502:1, s. 189-194
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Tidskriftsartikel (refereegranskat)abstract
- We have developed and successfully used several innovative designs of detectors with solid photocathodes. The main advantage of these detectors is that rather high gains (> 10(4)) can be achieved in a single multiplication step. This is possible by, for instance, exploiting the secondary electron multiplication and limiting the energy of the steamers by distributed resistivity. The single step approach also allows a very good position resolution to be achieved in some devices: 50 mum on line without applying any treatment method (like center of gravity). The main focus of our report is new fields of applications for these detectors and the optimization of their designs for such purposes.
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| 18. |
- Carlson, P., et al.
(författare)
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Gaseous photomultipliers with solid photocathodes for the detection of sparks, flames and dangerous gases
- 2003
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 505:02-jan, s. 207-210
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Tidskriftsartikel (refereegranskat)abstract
- In many applications, it is necessary to detect sparks or flames in daylight conditions or in illuminated areas. Most flames emit strongly in the ultraviolet spectrum (180-280 nm), and this property can be used for reliable identification of flames. We have developed new spark and flame detectors based on gaseous photomultipliers with CsI, CuI or CsTe photocathodes. A modified version of the detector can also detect smoke and dangerous vapors. These detectors are able to perform complex monitoring and detection functions. Some of their advantages are: low cost, high sensitivity, large output signal and operation under battery power. Gaseous photomultipliers can be position sensitive and, if necessary, be used in combination with various optical systems, for example for monitoring flames from space.
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| 19. |
- Danielsson, Mats, et al.
(författare)
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Novel gaseous detectors for medical imaging
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 518:1-2, s. 406-410
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Tidskriftsartikel (refereegranskat)abstract
- We have developed and successfully tested prototypes of two new types of gaseous detectors for medical imaging purposes. The first one is called the Electronic Portal Imaging Device (EPID). It is oriented on monitoring and the precise alignment of the therapeutic cancer treatment beam (pulsed gamma radiation) with respect to the patient's tumor position. The latest will be determined from an X-ray image of the patient obtained in the time intervals between the gamma pulses. The detector is based on a sandwich of hole-type gaseous detectors (GEM and glass microcapillary plates) with metallic gamma and X-ray converters coated with CsI layers. The second detector is an X-ray image scanner oriented on mammography and other radiographic applications. It is based on specially developed by us high rate RPCs that are able to operate at rates of 10(5) HZ/mm(2) with a position resolution better than 50 mum at 1 atm. The quality of the images obtained with the latest version of this device were in most cases more superior than those obtained from commercially available detectors.
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| 20. |
- Francke, T, et al.
(författare)
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High rate (up to 10(5) Hz/cm(2)), high position resolution (30 mu m) photosensitive RPCs
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 533:1-2, s. 163-168
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Tidskriftsartikel (refereegranskat)abstract
- In many applications there is a need for high position resolution VUV and UV imagers. For these applications we have developed and successfully tested 1D and 2D VUV imaging detectors based on microgap RPCs. Two versions of these detectors were extensively tested: one filled with photosensitive vapours and the other one with the GaAs cathode coated by a 400 nm thick CsI layer. The main feature of these detectors is the high position resolution-30 mum in digital form. Additionally, it is spark-protected and can operate at high counting rates (up to 10(5) Hz/cm(2)). In this study the results in application for these detectors for spectroscopy are presented.
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| 21. |
- Francke, T, et al.
(författare)
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Photosensitive gaseous detectors and their applications
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 525:1-2, s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- This paper reviews a large and important class of position sensitive detectors called photosensitive gaseous detectors (PGDs). Their main application rests in the imaging of UV photons. There are however, successful efforts to extend their sensitivity to visible light. With some modifications, PGDs can also be used in the imaging of X-rays and particles.
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| 22. |
- Iacobaeus, C., et al.
(författare)
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A high position resolution X-ray detector : An Edge on illuminated capillary plate combined with a gas amplification structure
- 2006
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Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 53:2, s. 554-561
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Tidskriftsartikel (refereegranskat)abstract
- We have developed and successfully tested a prototype of a new high position resolution hybrid X-ray detector. It contains a thin-wall lead glass capillary plate converter of X-rays combined with a microgap parallel-plate avalanche chamber operating in various gas mixtures at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0-90 degrees. The detection efficiency, depending on the geometry, photon's energy, incident angle and the mode of operation was between 5-30% in single step mode and up to 50% in a multi-layered combination. Depending on the capillary's geometry, the position resolution achieved was between 50-250 mu m in digital form and was practically independent of the photon's energy or gas mixture. The usual lead glass capillary plates operated without noticeable charging up effects at counting rates of 50 Hz/mm(2) and hydrogen treated capillaries-up to 10(5) Hz/mm(2). The developed detector has several important potential advantages over the exciting X-ray detectors and may open new possibilities for medical imaging, for example in mammography, portal imaging, radiography (including security devices), as well as many other applications.
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| 23. |
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| 24. |
- Iacobaeus, C., et al.
(författare)
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Advances in capillary-based gaseous UV imaging detectors
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 525:02-jan, s. 42-48
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Tidskriftsartikel (refereegranskat)abstract
- We studied gain and position resolution of gaseous UV-photon detectors combining single- and cascaded-glass capillary-plate multipliers and CsI photocathodes. Two modes of operation were investigated: a conventional one, where the main amplification occurs within capillary holes and a parallel-plate amplification mode, where the main amplification occurs between the capillary plate and the readout anode. Results of these studies demonstrate that in the parallel-plate amplification mode one can reach both high gains (> 10(5)) and good position resolutions (similar to 100 mum) even with a single-element multiplier. This offers a compact amplification structure, which can be used in many applications.
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| 25. |
- Iacobaeus, C., et al.
(författare)
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An X-ray scanner based on an "edge on" illuminated capillary plate combined with a gas amplification structure
- 2004
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Ingår i: 2004 IEEE Nuclear Science Symposium Conference Record. ; , s. 489-492
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Konferensbidrag (refereegranskat)abstract
- We have developed and successfully tested a prototype of a new type of high position resolution X-ray scanner. It contains a thin wall lead glass capillary plate converter of X-rays combined with a microgap parallel-plate avalanche chamber operating in various gas mixtures at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0-90°. The detection efficiency, depending on the geometry, photon's energy, incident angle and the mode of operation, was between 5-30% in a single step mode and up to 50% in a multi-layered combination. Depending on the capillary's geometry, the position resolution achieved was between 50-250 μm in digital form and was practically independent of the photon's energy or gas mixture. The usual lead glass capillary plates operated without noticeable charging up effects at counting rates of 50 Hz/mm2, and hydrogen treated capillaries up to 10 5 Hz/mm2. Finally, a prototype of the X-ray scanner based on an "edge-on" illumination capillary plate was built and tested. The developed detector open new possibilities for medical imaging, for example in mammography, portal imaging, radiography (including security devices), crystallography and many other applications.
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