Coleg Gwyddoniaeth a Pheirianneg

  1. Erthygl › Ymchwil › Adolygwyd gan gymheiriaid
  2. Cyhoeddwyd

    Moving the Goalposts: Possible Effects of Changes in Opportunity Costs on Conservation Triage

    Woodcock, P. & Hayward, M., 28 Medi 2016, Yn: Frontiers in Ecology and Evolution. 4, 113

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  3. Cyhoeddwyd

    Mre11 exonuclease activity removes the chain-terminating nucleoside analog gemcitabine from the nascent strand during DNA replication

    Böckemeier, L., Kraehenbuehl, R., Keszthelyi, A., Gasasira, M. U., Vernon, E., Beardmore, R., Broberg Vågbø, C., Chaplin, D., Collins, S., Krokan, H. E., Lambert, S. A. E., Paisz, B. & Hartsuiker, E., 29 Mai 2020, Yn: Science Advances. 6, 22, 9 t., eaaz4126.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  4. Cyhoeddwyd

    Mud crab pen culture: replacement of fish feed requirement and impacts on mangrove community structure.

    Primavera, J. H., Binas, J. B., Samonte-Tan, G. P., Lebata, M. J., Alava, V. R., Walton, M. & Le Vay, L., 1 Gorff 2010, Yn: Aquaculture Research. 41, 8, t. 1211-1220

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  5. Cyhoeddwyd

    Multi Locus Sequence Typing scheme for Acidithiobacillus caldus strain evaluation and differentiation

    Nuñez, H., Loyola, D., Cárdenas, J. P., Holmes, D. S., Johnson, D. & Quantrini, R., Tach 2014, Yn: Research in Microbiology. 165, 9, t. 735-742

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  6. Cyhoeddwyd

    Multi stress testing of OPV modules for accurate predictive ageing and reliability predictions

    Stoichkov, V., Kumar, D., Tyagi, P. & Kettle, J., Gorff 2018, Yn: IEEE Journal of Photovoltaics. 8, 4, t. 1058-1065

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  7. Cyhoeddwyd

    Multi-Constraint Gerchberg-Saxton Iteration Algorithms for Linearizing IM/DD Transmission Systems

    Hu, S., Zhang, J., Tang, J., Jin, T., Jin, W., Liu, Q., Zhong, Z., Giddings, R., Hong, Y., Xu, B., Yi, X. & Qiu, K., 14 Maw 2022, Yn: Optics Express. 30, 6, t. 10019-10031 13 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  8. Cyhoeddwyd

    Multi-Level Subcarrier Index-Power Modulated Optical OFDM with Adaptive Bit Loading for IMDD PON Systems

    Al Halabi, F., Chen, L., Giddings, R., Tang, J. & Hamie, A., 11 Tach 2016, Yn: IEEE Photonics Journal. 99

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  9. Cyhoeddwyd

    Multi-band carrier-less amplitude and phase modulation for bandlimited visible light communications systems

    Haigh, P. A., Le, S. T., Zvanovec, S., Ghassemlooy, Z., Luo, P., Xu, T., Chvojka, P., Kanesan, T., Giacoumidis, E., Canyelles-Pericas, P., Le Minh, H., Popoola, W., Rajbhandari, S., Papakonstantinou, I. & Darwazeh, I., 1 Ebr 2015, Yn: IEEE Wireless Communications. 22, 2, t. 46 - 53

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  10. Cyhoeddwyd

    Multi-century impacts of ice sheet retreat on sea level and ocean tides in Hudson Bay

    Hayden, A-M., Gomez, N., Wilmes, S-B. & Green, M., Tach 2020, Yn: Journal of Geophysical Research: Oceans. 125, 11

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  11. Cyhoeddwyd

    Multi-decadal change in summer mean water temperature in Lake Konnevesi, Finland (1984–2021)

    Noori, R., Woolway, R. I., Jun, C., Bateni, S. M., Naderian, D., Partani, S., Maghrebi, M. & Pulkkanen, M., 1 Rhag 2023, Yn: Ecological Informatics. 78, 102331.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  12. Cyhoeddwyd

    Multi-dimensional Hermite polynomials in quantum optics.

    Kok, P. & Braunstein, S. L., 10 Awst 2001, Yn: Journal of Physics A - Mathematical and General. 34, 31, t. 6185-6195

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  13. Cyhoeddwyd

    Multi-interface roughness effects on electron mobility in a Ga0.5In0.5P/GaAs multisubband coupled quantum well structure.

    Sahu, T. & Shore, K. A., 1 Medi 2009, Yn: Semiconductor Science and Technology. 24, 9, t. 095021

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  14. Cyhoeddwyd

    Multi-locus phylogeny and species delimitation of Australo-Papuan blacksnakes(Pseudechis Wagler, 1830: Elapidae: Serpentes)

    Maddock, S., Childerstone, A., Fry, B. G., Williams, D. J., Barlow, A. & Wüster, W., 1 Chwef 2017, Yn: Molecular Phylogenetics and Evolution. 107, February, t. 48-55

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  15. Cyhoeddwyd

    Multi-mode self-pulsation in laser diodes with epitaxially integrated saturable absorbers: mode competition and carrier dynamics.

    Pierce, I., Summer, H. D., Rees, P. & Jones, D. R., 1 Ebr 2003, Yn: IEE Proceedings: Optoelectronics. 150, 2, t. 159-162

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  16. Cyhoeddwyd

    Multi-model projections of future evaporation in a sub-tropical lake

    La Fuente, S., Jennings, E., Gal, G., Kirillin, G., Shatwell, T., Ladwig, R., Moore, T., Couture, R-M., Cote, M., Vinna, C. L. R. & Woolway, R. I., Rhag 2022, Yn: Journal of Hydrology. 615, 128729.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  17. Cyhoeddwyd

    Multi-scale assessment of distribution and density of procellariiform seabirds within the Northern Antarctic Peninsula marine ecosystem

    Warwick-Evans, V., Santora, J., Waggitt, J. & Trathan, P., 1 Awst 2021, Yn: ICES Journal of Marine Science. 78, 4, t. 1324-1339

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  18. Cyhoeddwyd

    Multi-scale pedestrian intent prediction using 3D joint information as spatio-temporal representation

    Ahmed, S., Al Bazi, A., Saha, C., Rajbhandari, S. & Huda, M. N., 1 Medi 2023, Yn: Expert Systems with Applications. 225, 120077.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  19. Cyhoeddwyd

    Multi-view autostereoscopic system for 3D visualization in anatomy

    Magalhães, D. S. F., Mansoor, S., Weng, Y., Ghizoni, E., Barbosa, T., Silveira, F. D. A., Toledo, R. S. & Li, L. M., 2018, Yn: Research on Biomedical Engineering. 34, 3, t. 279-283

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  20. Cyhoeddwyd

    Multi-year observations on the gametogenic ecology of the Antarctic seastar Odontaster validus

    Grange, L. J., Tyler, P. A. & Peck, L. S., Tach 2007, Yn: Marine Biology. 153, 1, t. 15-23

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  21. Cyhoeddwyd

    Multi-year observations on the gametogenic ecology of the Antarctic seastar Odontaster validus (vol 153, pg 15, 2007)

    Grange, L. J., Tyler, P. A. & Peck, L. S., Gorff 2011, Yn: Marine Biology. 158, 7, t. 1681-1681

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  22. Cyhoeddwyd

    Multifunctional properties of Z-beta-(N-hexadecyl-4-quinolinium)-alpha-cyano-4-styryldicyanomethanide: a molecular rectifier, optically non-linear dye, and ammonia sensor

    Ashwell, G. J. & Paxton, G. A., 1 Ion 2002, Yn: Australian Journal of Chemistry. 55, 3, t. 199-204

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  23. Cyhoeddwyd

    Multifunctional thermally transitioning oligopeptides prepared by ring-opening metathesis polymerization

    Roberts, S. K., Roberts, K. S., Chilkoti, A. & Setton, L. A., 1 Ion 2007, Yn: Biomacromolecules. 8, 8, t. 2618-2621

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  24. Cyhoeddwyd

    Multilevel comparison of Indian Naja venoms and their cross-reactivity with Indian polyvalent antivenoms

    Deka, A., Bhatia, S., Santra, V., Bharti, O., Lalremsanga, H., Martin, G., Wüster, W., Owens, J. B., Graham, S., Doley, R. & Malhotra, A., 1 Ebr 2023, Yn: Toxins. 15, 4, 24 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  25. Cyhoeddwyd

    Multilocus phylogeny, species age and biogeography of the Lesser Antillean anoles

    Thorpe, R., Barlow, A., Surget-Groba, Y. & Malhotra, A., Hyd 2018, Yn: Molecular Phylogenetics and Evolution. 127, t. 682-695

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  26. Cyhoeddwyd

    Multilocus phylogeography of the brown-spotted pitviper Protobothrops mucrosquamatus (Reptilia: Serpentes: Viperidae) sheds a new light on the diversification pattern in Asia

    Guo, P., Liu, Q., Zhu, F., Zhong, G. H., Che, J., Wang, P., Xie, Y. L., Murphy, R. W. & Malhotra, A., Ebr 2019, Yn: Molecular Phylogenetics and Evolution. 133, t. 82-91

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  27. Cyhoeddwyd

    Multilocus sequence typing provides insights into the population structure and evolutionary potential of Brenneria goodwinii, associated with acute oak decline

    Kaczmarek, M., Mullett, M. S., McDonald, J. & Denman, S., 1 Meh 2017, Yn: PLoS ONE. 12, 6, e0178390.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  28. Cyhoeddwyd

    Multimodal correlative imaging and modelling of phosphorus uptake from soil by hyphae of mycorrhizal fungi

    Keyes, S., van Veelen, A., Fletcher, D. M., Scotson, C., Koebernick, N., Petroselli, C., Williams, K., Ruiz, S., Cooper, L., Mayon, R., Duncan, S., Dumont, M., Jakobsen, I., Oldroyd, G., Tkacz, A., Poole, P., Mosselmans, F., Borca, C., Huthwelker, T., Jones, D. L. & Roose, T., 1 Ebr 2022, Yn: New Phytologist. 234, 2, t. 688-703 16 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  29. Cyhoeddwyd

    Multimode dynamics in laser diodes with optical feedback.

    Pierce, I., Rees, P. & Spencer, P. S., 1 Mai 2000, Yn: Physical Review A. 61, 5, t. 053801

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  30. Cyhoeddwyd

    Multiphysics modelling and simulation of dry laser cleaning of micro-slots with particle contaminants

    Yue, L., Wang, Z. & Li, L., 12 Maw 2012, Yn: Journal of Physics D: Applied Physics. 45, 13, t. 135401

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  31. Cyhoeddwyd

    Multiple Channel Interference Cancellation of Digital Filter Multiple Access PONs

    Dong, Y., Al-Rawachy, E., Giddings, R. P., Jin, W., Nesset, D. & Tang, J., Ion 2017, Yn: Journal of Lightwave Technology. 35, 1, t. 34-44

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  32. Cyhoeddwyd

    Multiple Views: different meanings and collocated words

    Roberts, J. C., Al-Maneea, H. M. A., Butcher, P., Lew, R., Rees, G., Sharma, N. & Frankenberg-Garcia, A., Meh 2019, Yn: Computer Graphics Forum. 38, 3, t. 79-93 14 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  33. Cyhoeddwyd

    Multiple causation of phylogeographical pattern as revealed by nested clade analysis of the bamboo viper (Trimeresurus stejnegeri) within Taiwan.

    Creer, S., Malhotra, A., Thorpe, R. S. & Chou, W. H., 1 Awst 2001, Yn: Molecular Ecology. 10, 8, t. 1967-1981

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  34. Cyhoeddwyd

    Multiple drivers of decline in the global status of freshwater crayfish (Decapoda: Astacidea)

    Richman, N., Richman, N. I., Bohm, M., Adams, S. B., Alvarez, F., Bergey, E. A., Bunn, J. S., Burnham, Q., Cordeiro, J., Coughran, J., Crandall, K. A., Dawkins, K. L., DiStefano, R. J., Doran, N. E., Edsman, L., Eversole, A. G., Fureder, L., Furse, J. M., Gherardi, F., Hamr, P., Holdich, D. M., Horwitz, P., Johnston, K., Jones, C. M., Jones, J. P., Jones, R. L., Jones, T. G., Kawai, T., Lawler, S., Lopez-Mejia, M., Miller, R. M., Padraza-Lara, C., Reynolds, J. D., Richardson, A. M., Schultz, M. B., Schuster, G. A., Sibley, P. J., Souty-Grosset, C., Taylor, C. A., Thoma, R. F., Walls, J., Walsh, T. S. & Collen, B., 5 Ion 2015, Yn: Philosophical Transactions of the Royal Society B. 370, 1662

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  35. Cyhoeddwyd

    Multiple linker Half-squarylium Dyes for Dye-Sensitized Solar Cells; Are Two Linkers Better than One?

    Furnell, L. W., Kershaw, C. P., Connell, A., Holliman, P. J., Jones, E. W., Furnell, L., Kershaw, C., Davies, M. L., Gwenin, C. D., Pitak, M. B., Coles, S. J. & Cooke, G., 16 Rhag 2014, Yn: Journals of Materials Chemistry A. 3, 6, t. 2883-2894

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  36. Cyhoeddwyd

    Multiple origins of viviparity, or reversal from viviparity to oviparity? The European common lizard (Zootoca vivipara, Lacertidae) and the evolution of parity.

    Surget-Groba, Y., Heulin, B., Guillaume, C. P., Puky, M., Semenov, D., Orlova, V., Kupriyanova, L., Ghira, I. & Smajda, B., 1 Ion 2006, Yn: Biological Journal of the Linnean Society. 87, 1, t. 1-11

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  37. Cyhoeddwyd

    Multiple paths to aquatic specialisation in four species of Central American Anolis lizards

    Munoz, M. M., Crandell, K. E., Campbell-Staton, S. C., Fenstermacher, K., Frank, H. K., Van Middlesworth, P., Sasa, M., Losos, J. B. & Herrel, A., 26 Gorff 2015, Yn: Journal of Natural History. 49, 27-28, t. 1717-1730

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  38. Cyhoeddwyd

    Multiple stressors facilitate the spread of a non-indigenous bivalve in the Mediterranean Sea

    Mangano, M., Sara, G., Porporato, E. M. D. & Mieszkowska, N., 17 Chwef 2018, Yn: Journal of Biogeography.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  39. Cyhoeddwyd

    Multiple trait dimensions mediate stress gradient effects on plant biomass allocation, with implications for coastal ecosystem services.

    de Battisti, D., Fowler, M. S., Jenkins, S., Skov, M., Bouma, T. J., Neyland, P. J. & Griffin, J., Gorff 2020, Yn: Journal of Ecology. 108, 4, t. 1227-1240

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  40. Cyhoeddwyd

    Multiplex chaos synchronization in semiconductor lasers with multiple optoelectronic feedbacks

    Shahverdiev, E., Shahverdiev, E. M. & Shore, K. A., 1 Meh 2013, Yn: Optik - International Journal for Light and Electron Optics. 124, 12, t. 1350-1353

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  41. Cyhoeddwyd

    Multisensor Acoustic Tracking of Fish and Seabird Behavior Around Tidal Turbine Structures in Scotland

    Williamson, B. J., Fraser, S., Blondel, P., Bell, P. S., Waggitt, J. J. & Scott, B. E., 17 Ion 2017, Yn: IEEE JOURNAL OF OCEANIC ENGINEERING. 42, 4, t. 948-965

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  42. Cyhoeddwyd

    Multivalent glycoconjugates as anti-pathogenic agents

    Bernardi, A., Jimenez-Barbero, J., Casnati, A., De Castro, C., Darbre, T., Fieschi, F., Finne, J., Funken, H., Jaeger, K-E., Lahmann, M., Lindhorst, T. K., Marradi, M., Messner, P., Molinaro, A., Murphy, P. V., Nativi, C., Oscarson, S., Penades, S., Peri, F., Pieters, R. J., Renaudet, O., Reymond, J-L., Richichi, B., Rojo, J., Sansone, F., Schaeffer, C., Turnbull, W. B., Velasco-Torrijos, T., Vidal, S., Vincent, S., Wennekes, T., Zuilhof, H. & Imberty, A., 2013, Yn: Chemical Society Reviews. 42, 11, t. 4709-4727

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  43. Cyhoeddwyd

    Multivariate Approach for Studying the Degradation of Perovskite Solar Cells.

    Kettle, J., Tyagi, P., David, T. & Stoichkov, V., 15 Tach 2019, Yn: Solar Energy. 193, t. 12-19

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  44. Cyhoeddwyd

    Multivariate statistical methods in Environmental Forensics

    Mudge, S. M., 1 Maw 2007, Yn: Environmental Forensics. 8, 1-2, t. 155-163

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  45. Cyhoeddwyd

    Multiyear trend in reproduction underpins interannual variation in gametogenic development of an Antarctic urchin.

    De Leij, R., Peck, L. S. & Grange, L., 22 Medi 2021, Yn: Scientific Reports. 11, 1, 18868.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  46. Cyhoeddwyd

    Museum DNA reveals a new, potentially extinct species of rinkhals (Serpentes: Elapidae: Hemachatus) from the Eastern Highlands of Zimbabwe

    Major, T., Renk, P., Reissig, J., Paijmans, J., Morris, E., Hofreiter, M., Barlow, A., Broadley, D. G. & Wüster, W., 27 Medi 2023, Yn: PLoS ONE. 18, 9, 19 t., e0291432.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  47. Cyhoeddwyd

    Mutation in a "tesB-like" hydroxyacyl-coenzyme A-specific thioesterase gene causes hyperproduction of extracelluar polyhydroxyalkanoates by Alcanivorax orkumensis SK2.

    Golyshin, P., Sabirova, J. S., Ferrer, M., Lunsdorf, H., Wray, V., Kalscheuer, R., Steinbuchel, A., Timmis, K. N. & Golyshin, P. N., 1 Rhag 2006, Yn: Journal of Bacteriology. 188, 24, t. 8452-8459

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  48. Cyhoeddwyd

    Mutational Meltdown in Primary Endosymbionts: Selection Limits Muller's Ratchet.

    Allen, J. M., Light, J. E., Perotti, M. A., Braig, H. R. & Reed, D. L., 23 Maw 2009, Yn: PLoS ONE. 4, 3, t. e4969

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  49. Cyhoeddwyd

    Mutational analysis of the critical bases involved in activation of the AreR-regulated sigma(54)-dependent promoter in Acinetobacter sp strain ADP1.

    Jones, R. M. & Williams, P. A., 1 Medi 2003, Yn: Applied and Environmental Microbiology. 69, 9, t. 5627-5635

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  50. Cyhoeddwyd

    Mycobacterium alvei (ω-1)-methoxy mycolic acids: Absolute stereochemistry and synthesis

    Alhuwaymil, Z. S., Al-araj, I. Q. M., Dulayymi, A. R. A., Jones, A., Gates, P. J., Valero-Guillén, P. L., Baird, M. S. & Dulayymi, J. R. A., Tach 2020, Yn: Chemistry and Physics of Lipids. 233, 1 t., 104977.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  51. Cyhoeddwyd

    Mycobacterium tuberculosis-associated synthetic mycolates differentially exert immune stimulatory adjuvant activity

    Smet, M., Pollard, C., De Beuckelaer, A., Van Hoecke, L., Beken, S. V., De Koker, S., Al-Dulayymi, J. R., Huygen, K., Verschoor, J., Baird, M. & Grooten, J., 7 Medi 2016, Yn: European Journal of Immunology. 46, t. 2149-2154 6 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid