| 1. |
- Fattibene, P, et al.
(författare)
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The 4th international comparison on EPR dosimetry with tooth enamel Part 1: Report on the results
- 2011
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Ingår i: Radiation Measurements. - : Elsevier. - 1350-4487 .- 1879-0925. ; 46:9, s. 765-771
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of the 4th International Comparison of in vitro electron paramagnetic resonance dosimetry with tooth enamel, where the performance parameters of tooth enamel dosimetry methods were compared among sixteen laboratories from all over the world. The participating laboratories were asked to determine a calibration curve with a set of tooth enamel powder samples provided by the organizers. Nine molar teeth extracted following medical indication from German donors and collected between 1997 and 2007 were prepared and irradiated at the Helmholtz Zentrum Munchen. Five out of six samples were irradiated at 0.1, 0.2, 0.5, 1.0 and 1.5 Gy air kerma; and one unirradiated sample was kept as control. The doses delivered to the individual samples were unknown to the participants, who were asked to measure each sample nine times, and to report the EPR signal response, the mass of aliquots measured, and the parameters of EPR signal acquisition and signal evaluation. Critical dose and detection limit were calculated by the organizers on the basis of the calibration-curve parameters obtained at every laboratory. For calibration curves obtained by measuring every calibration sample three times, the mean value of the detection limit was 205 mGy, ranging from 56 to 649 mGy. The participants were also invited to provide the signal response and the nominal dose of their current dose calibration curve (wherever available), the critical dose and detection limit of which were also calculated by the organizers.
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| 2. |
- Dhanaya, M. B., et al.
(författare)
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Proton entry into the near-lunar plasma wake for magnetic field aligned flow
- 2013
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 40:2, s. 2913-2917
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Tidskriftsartikel (refereegranskat)abstract
- We report the first observation of protons in the near-lunar (100–200 km from the surface) and deeper (near anti-subsolar point) plasma wake when the interplanetary magnetic field (IMF) and solar wind velocity (vsw) are parallel (aligned flow; angle between IMF and vsw≤10°). More than 98% of the observations during aligned flow condition showed the presence of protons in the wake. These observations are obtained by the Solar Wind Monitor sensor of the Sub-keV Atom Reflecting Analyser experiment on Chandrayaan-1. The observation cannot be explained by the conventional fluid models for aligned flow. Back tracing of the observed protons suggests that their source is the solar wind. The larger gyroradii of the wake protons compared to that of solar wind suggest that they were part of the tail of the solar wind velocity distribution function. Such protons could enter the wake due to their large gyroradii even when the flow is aligned to IMF. However, the wake boundary electric field may also play a role in the entry of the protons into the wake.
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| 3. |
- Ainsbury, E A, et al.
(författare)
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REVIEW OF RETROSPECTIVE DOSIMETRY TECHNIQUES FOR EXTERNAL IONISING RADIATION EXPOSURES.
- 2011
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 147:4, s. 573-592
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Tidskriftsartikel (refereegranskat)abstract
- The current focus on networking and mutual assistance in the management of radiation accidents or incidents has demonstrated the importance of a joined-up approach in physical and biological dosimetry. To this end, the European Radiation Dosimetry Working Group 10 on 'Retrospective Dosimetry' has been set up by individuals from a wide range of disciplines across Europe. Here, established and emerging dosimetry methods are reviewed, which can be used immediately and retrospectively following external ionising radiation exposure. Endpoints and assays include dicentrics, translocations, premature chromosome condensation, micronuclei, somatic mutations, gene expression, electron paramagnetic resonance, thermoluminescence, optically stimulated luminescence, neutron activation, haematology, protein biomarkers and analytical dose reconstruction. Individual characteristics of these techniques, their limitations and potential for further development are reviewed, and their usefulness in specific exposure scenarios is discussed. Whilst no single technique fulfils the criteria of an ideal dosemeter, an integrated approach using multiple techniques tailored to the exposure scenario can cover most requirements.
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| 4. |
- Brinkfeldt, Klas, et al.
(författare)
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Microshutters for MEMS-based time-of-flight measurements in space
- 2011
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Ingår i: Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS). - 1084-6999. - 9781424496327 ; , s. 597-600
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Konferensbidrag (refereegranskat)abstract
- This paper reports on the fabrication, integration and first operation of a mechanical microshutter in a time-of-flight (TOF) based ion detector in space. The microshutter is fabricated from a silicon on insulator (SOI) wafer and operated in a resonance mode, 306 kHz. Open time of the shutter is 100 ns. The microshutters are integrated in the PRIMA instrument, which is part of the payload on the Swedish PRISMA mission. PRISMA was successfully launched into low Earth orbit on June 15, 2010.
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| 5. |
- Brinkfelt, Klas, 1976, et al.
(författare)
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Microshutters for space physics time of flight applications
- 2010
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Ingår i: 21st Micromechanics and Micro systems Europe workshop, 26-29 September 2010, Enschede, The Netherlands. ; , s. 140-143
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Konferensbidrag (refereegranskat)abstract
- In present time-of-flight (TOF) mass and energy spectrometers in experimental space plasmaphysics applications, the resolution is limited by the fact that the particle to be measured loses part of its energyin the generation of the start pulse. To improve the resolution, a fast micromechanical shutter system togenerate the start signal has been developed. The microshutter is included in the PRIMA (PRIsma MassAnalyzer) ion detector on-board the Swedish PRISMA mission, which will be launched into low Earth orbit onJune 15, 2010.
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| 6. |
- Fattibene, Paola, et al.
(författare)
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EPR dosimetry intercomparison using smart phone touch screen glass
- 2014
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Ingår i: Radiation and Environmental Biophysics. - : Springer-Verlag New York. - 0301-634X .- 1432-2099. ; 53:2, s. 311-320
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of an interlaboratory comparison of retrospective dosimetry using the electron paramagnetic resonance method. The test material used in this exercise was glass coming from the touch screens of smart phones that might be used as fortuitous dosimeters in a large-scale radiological incident. There were 13 participants to whom samples were dispatched, and 11 laboratories reported results. The participants received five calibration samples (0, 0.8, 2, 4, and 10 Gy) and four blindly irradiated samples (0, 0.9, 1.3, and 3.3 Gy). Participants were divided into two groups: for group A (formed by three participants), samples came from a homogeneous batch of glass and were stored in similar setting; for group B (formed by eight participants), samples came from different smart phones and stored in different settings of light and temperature. The calibration curves determined by the participants of group A had a small error and a critical level in the 0.37-0.40-Gy dose range, whereas the curves determined by the participants of group B were more scattered and led to a critical level in the 1.3-3.2-Gy dose range for six participants out of eight. Group A were able to assess the dose within 20 % for the lowest doses (< 1.5 Gy) and within 5 % for the highest doses. For group B, only the highest blind dose could be evaluated in a reliable way because of the high critical values involved. The results from group A are encouraging, whereas the results from group B suggest that the influence of environmental conditions and the intervariability of samples coming from different smart phones need to be further investigated. An alongside conclusion is that the protocol was easily transferred to participants making a network of laboratories in case of a mass casualty event potentially feasible.
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| 7. |
- Flohr, E. L. R., et al.
(författare)
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THE FATE OF THE INNER NOSE : ODOR IMAGERY IN PATIENTS WITH OLFACTORY LOSS
- 2014
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522 .- 1873-7544. ; 268, s. 118-127
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral activations during olfactory mental imagery are fairly well investigated in healthy participants but little attention has been given to olfactory imagery in patients with olfactory loss. To explore whether olfactory loss leads to deficits in olfactory imagery, neural responses using functional magnetic resonance imaging (fMRI) and self-report measures were investigated in 16 participants with acquired olfactory loss and 19 control participants. Participants imagined both pleasant and unpleasant odors and their visual representations. Patients reported less vivid olfactory but not visual images than controls. Results from neuroimaging revealed that activation patterns differed between patients and controls. While the control group showed stronger activation in olfactory brain regions for unpleasant compared to pleasant odors, the patient group did not. Also, activation in critical areas for olfactory imagery was correlated with the duration of olfactory dysfunction, indicating that the longer the duration of dysfunction, the more the attentional resources were employed. This indicates that participants with olfactory loss have difficulties to perform olfactory imagery in the conventional way. Regular exposure to olfactory information may be necessary to maintain an olfactory imagery capacity.
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| 8. |
- Futaana, Y, et al.
(författare)
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Remote energetic neutral atom imaging of electric potential over a lunar magnetic anomaly
- 2013
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Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 40:2, s. 262-266
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Tidskriftsartikel (refereegranskat)abstract
- The formation of electric potential over lunar magnetized regions is essential for understanding fundamental lunar science, for understanding the lunar environment, and for planning human exploration on the Moon. A large positive electric potential was predicted and detected from single point measurements. Here, we demonstrate a remote imaging technique of electric potential mapping at the lunar surface, making use of a new concept involving hydrogen neutral atoms derived from solar wind. We apply the technique to a lunar magnetized region using an existing dataset of the neutral atom energy spectrometer SARA/CENA on Chandrayaan-1. Electrostatic potential larger than +135 V inside the Gerasimovic anomaly is confirmed. This structure is found spreading all over the magnetized region. The widely spread electric potential can influence the local plasma and dust environment near the magnetic anomaly. Citation: Futaana, Y., S. Barabash, M. Wieser, C. Lue, P. Wurz, A. Vorburger, A. Bhardwaj, and K. Asamura (2013), Remote energetic neutral atom imaging of electric potential over a lunar magnetic anomaly, Geophys. Res. Lett., 40, 262-266, doi:10.1002/grl.50135.
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| 9. |
- Gunell, H., et al.
(författare)
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Waves in high-speed plasmoids in the magnetosheath and at the magnetopause
- 2014
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 32:8, s. 991-1009
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Tidskriftsartikel (refereegranskat)abstract
- Plasmoids, defined here as plasma entities with a higher anti-sunward velocity component than the surrounding plasma, have been observed in the magnetosheath in recent years. During the month of March 2007 the Cluster spacecraft crossed the magnetopause near the subsolar point 13 times. Plasmoids with larger velocities than the surrounding magnetosheath were found on seven of these 13 occasions. The plasmoids approach the magnetopause and interact with it. Both whistler mode waves and waves in the lower hybrid frequency range appear in these plasmoids, and the energy density of the waves inside the plasmoids is higher than the average wave energy density in the magnetosheath. When the spacecraft are in the magnetosphere, Alfvenic waves are observed. Cold ions of ionospheric origin are seen in connection with these waves, when the wave electric and magnetic fields combine with the Earth's dc magnetic field to yield an E x B/B-2 drift speed that is large enough to give the ions energies above the detection threshold.
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| 10. |
- Lue, Charles, et al.
(författare)
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Strong influence of lunar crustal fields on the solar wind flow
- 2011
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 38:3
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Tidskriftsartikel (refereegranskat)abstract
- We discuss the influence of lunar magnetic anomalies on the solar wind and on the lunar surface, based on maps of solar wind proton fluxes deflected by the magnetic anomalies. The maps are produced using data from the Solar WInd Monitor (SWIM) onboard the Chandrayaan-1 spacecraft. We find a high deflection efficiency (average ∼10%, locally ∼50%) over the large-scale (>1000 km) regions of magnetic anomalies. Deflections are also detected over weak (<3 nT at 30 km altitude) and small-scale (<100 km) magnetic anomalies, which might be explained by charge separation and the resulting electric potential. Strong deflection from a wide area implies that the magnetic anomalies act as a magnetosphere-like obstacle, affecting the upstream solar wind. It also reduces the implantation rate of the solar wind protons to the lunar surface, which may affect space weathering near the magnetic anomalies.
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