Browsing by Author "Hoekstra, S."
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- Test of Lorentz invariance in beta decay of polarized Na-20Publication . Sytema, A.; van den Berg, J. E.; Boll, O.; Chernowitz, D.; Dijck, E. A.; Grasdijk, J. O.; Hoekstra, S.; Jungmann, K.; Mathavan, S. C.; Meinema, C.; Mohanty, A.; Muller, S. E.; Noordmans, J. P.; Portela, M. Nunez; Onderwater, C. J. G.; Pijpker, C.; Timmermans, R. G. E.; Vos, K. K.; Willmann, L.; Wilschut, H. W.Background: Lorentz invariance is key in our understanding of nature, yet relatively few experiments have tested Lorentz invariance in weak interactions.Purpose: Our goal is to obtain limits on Lorentz-invariance violation in weak interactions, in particular rotational invariance in beta decay.Method: We search for a dependence of the lifetime of Na-20 nuclei on the nuclear spin direction. Such directional dependence would be evidence for Lorentz-invariance violation in weak interactions. A difference in lifetime between nuclei that are polarized in the east and west direction is searched for. This difference is maximally sensitive to the rotation of the Earth, while the sidereal dependence is free from most systematic errors.Results: The experiment sets a limit of 2 x 10(-4) at 90% C.L. on the amplitude of the sidereal variation of the relative lifetime differences, an improvement by a factor 15 compared to an earlier result.Conclusions: No significant violation of Lorentz invariance is found. The result sets limits on parameters of theories describing Lorentz-invariance violation.
- Updated global conservation status and priorities for marine turtlesPublication . Wallace, B. P.; Bandimere, A. N.; Abreu-Grobois, F. A.; Acosta, H.; Akiti, J.; Akomedi, M.; Alfaro-Shigueto, J.; Allen, C. D.; Angenda, D.; Ayissi, I.; Ricardo, J. Azanza; Barrientos-Muñoz, K. G.; Barrios-Garrido, H.; Bjorndal, K. A.; Vargas, E. Bretón; Broderick, A. C.; Peña, R. Calderón; Carreras, C.; Ceriani, S. A.; Colman, L. P.; Cortés-Gómez, A. A.; Crespo, L.; Cuevas, E.; Dah, A.; Groene, A de; Trejo, C. Delgado; Demetropoulos, S.; Dias, A.; Diez, C.; Santos, N. A. dos; Bodjrenou, J. S. Dossou; Capistrán, M. M. Early; Eckert, K. L.; Eizaguirre, C.; Ekanayake, L.; Mondragón, M. Escobedo; Esteban, N.; Feliciano, D.; Fernandes, R. S.; Ferreira-Airaud, Betânia; Foley, A.; Fonseca, L. G.; Martín-Viaña, Y. Forneiro; Fossette, S.; Fuentes, M. M. P. B.; Gaglo, J.; Gaos, A. R.; Gidsicki, D.; Giffoni, B.; Girard, A.; Girondot, M.; Godfrey, M. H.; Godley, B. J.; Mirón, R. J. González Díaz; Hamann, M.; Hancock, J. M.; Hart, C. E.; Hays, G. C.; Herrera, R.; Hochscheid, S.; Hoekstra, S.; Huerta-Rodríguez, P.; Inteca, G.; Ishihara, T.; Jensen, M. P.; Jribi, I.; Kale, N.; Kaska, Y.; Kelez, S.; Kelly, I. K.; Köhnk, S.; Lara, P.; Lasfargue, M.; Lauritsen, A. M.; Gouvello, D. Z. M. Le; Liusamoa, A.; López, M.; López-Castro, M. C.; Lopez-Mendilaharsu, M.; Louro, C. M. M.; Luna, T.; Madden, C. A.; Mahabir, D.; Mancini, A.; Manoharakrishnan, M.; Marcovaldi, M. A.; Martínez-Portugal, R. C.; Mastrogiacomo, A.; Matilde, E. I. O. P.; Adzagba, B. Mawunyo; Mbungu, S.; Miranda, C.; Moncada, F.; Morales-Mérida, B. A.; Mortimer, J. A.; Murakawa, S. K. K.; Nalovic, M. A.; Nel, R.; Ngafack, R.; Nishizawa, H.; Ogou, M.; Panagopoulou, A.; Patricio, A. R.; Buendía, E. Peralta; Phillott, A. D.; Pilcher, N. J.; Polyak, M. M. R.; Prince, R. I. T.; Raynus, E. H.; Reina, R. D.; Rguez-Baron, J. M.; Robbins, A. E.; Santos, A. S.; Sarti-Martínez, A. L.; Schofield, G.; Seminoff, J. A.; Serrano, I.; Shamblin, B. M.; Shanker, K.; Stacy, B. A.; Stahelin, G.; Staman, M. K.; Stelfox, M.; Stewart, K. R.; Taxonera, A.; Tucker, A. D.; Turkozan, O.; Dam, R. P. van; Geer, C. H .van de; Viera, S.; West, L.; Whiting, A. U.; Whiting, S. D.; Wienand, L.; Wijntuin, S. R.; Wildermann, N.; Zárate, P. M.; Casale, P.; DiMatteo, A.; Hurley, B. J.; Hutchinson, B. J.; Maxwell, S. M.; Posnik, Z. A.; Rodriguez, I.; Mast, R. B.Assessing conservation status and pursuing applicable management priorities for marine megafauna across multiple scales pose significant challenges. Because marine turtles exemplify these challenges, the IUCN Marine Turtle Specialist Group (MTSG) developed the 'conservation priorities portfolio' (CPP) framework in 2011 to evaluate population risk and threats for regional management units (RMUs). Here, the MTSG has updated the 2011 CPP framework through an inclusive assessment process. Expert elicitation results involving 145 individuals from 50 countries suggests that marine turtle conservation status appears to be improving, but significant challenges remain. Since the previous assessment, long-term abundance trends increased on average, and threat impact scores improved for nearly twice as many RMUs (53%) as worsened (28%) (>= 10% threshold for changes in numeric scores). While expert-assessed threat impacts have generally decreased, fisheries bycatch remains the highest scored threat across regions and species. Risk-threat staus improved for most (54%) RMUs. Over 40% of RMUs were scored as low risk-low threats, of which 8 were green turtles Chelonia mydas RMUs. Less than 20% of RMUs were scored as high risk-high threats, of which 4 were leatherback turtles Dermochelys coriacea. Most high risk-high threats RMUs were in the Pacific Ocean, while most low risk-low threats RMUs were in the Atlantic Ocean. Eleven RMUs were evaluated as having critical data needs. Our results-also provided through an interactive data dashboard-underscore the importance of context-specific planning to effectively target limited conservation resources. Future assessments should further prioritize inclusion of under-represented topics, researchers, and regions to better address multi-faceted conservation challenges. Macroalgae;