Ysgol Gwyddorau Eigion

  1. Pennod › Ymchwil › Heb ei adolygu gan gymheiriaid
  2. Cyhoeddwyd

    The phase lag of turbulent dissipation in tidal flow.

    Simpson, J. H., Rippeth, T. P., Campbell, A. R. & Yanagi, T. (gol.), 1 Ion 2000, Interactions between Estuaries: Coastal Seas and Shelf Seas. 2000 gol. Terra Scientific Publishing, t. 57-67

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  3. Cyhoeddwyd

    The reefs of Mauritius

    Turner, J. R., Hardman, E., Klaus, R., Fagoonee, I., Daby, D., Baghooli, R., Persands, S., Souter, D. (gol.), Obura, D. (gol.) & Linden, O. (gol.), 1 Ion 2000, Coral Reef Degradation in the Indian Ocean. 2000 gol. Stockholm University, CORDIO, t. 94-107

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  4. Cyhoeddwyd

    The reefs of the granitic islands of the Seychelles

    Turner, J. R., Klaus, R., Engelhardt, U., Souter, D. (gol.), Obura, D. (gol.) & Linden, O. (gol.), 1 Ion 2000, Coral Reef Degradation in the Indian Ocean. 2000 gol. Stockholm University, CORDIO, t. 77-86

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  5. Cyhoeddwyd

    The statistical design of feeding experiments

    Ruohonen, K., Kettunen, J., King, J. W., Houlihan, D. (gol.), Boujard, T. (gol.) & Jobling, M. (gol.), 1 Ion 2001, Feed Intake in Fish. 2001 gol. Blackwell Scientific, t. 88-107

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  6. Cyhoeddwyd

    Tidal Stream Energy

    Ward, S., 2022, Comprehensive Renewable Energy. 2 gol. Oxford: Elsevier, Cyfrol 8. t. 104-122 (Comprehensive Renewable Energy).

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  7. Cyhoeddwyd

    Tides

    Ward, S., 2021, 30-Second Oceans: 50 key ideas about the sea's importance to life on earth. Green, M. & Lenn, Y-D. (gol.). The Ivy Press

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  8. Cyhoeddwyd

    UWB 1DV sand transport model

    Malarkey, J., Van Rijn, L. C. (gol.), Soulsby, R. L. (gol.), Hoekstra, P. (gol.) & Davies, A. G. (gol.), 1 Ion 2005, SANDPIT: Sand Transport and Morphology of Offshore Sand Mining Pits. 2005 gol. Aqua Publications, t. 1-8

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  9. Cyhoeddwyd

    Variation in sea trout (Salmo trutta) abundance and life histories in the Irish Sea

    Milner, N., Potter, E., Roche, W., Tysklind, N., Davidson, I., King, J., Coyne, J. & Davies, C., Tach 2017, Sea Trout: Science and Management: Proceedings of the 2nd International Sea Trout Symposium. Harris, G. (gol.). Kibworth Beauchamp: Matador, t. 96-128 32 t. 5

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  10. Cyhoeddwyd

    Watermill Cove.

    Scourse, J. D., Rhodes, E. J. & Scourse, J. D. (gol.), 1 Ion 2006, The Isles of Scilly: Field Guide. 2006 gol. Quaternary Research Association, London, t. 66-72

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  11. Cyhoeddwyd

    Why is there a tide?

    Ward, S., Bowers, D., Green, M. & Wilmes, S-B., 7 Hyd 2022, A Journey Through Tides. Green, M. & Duarte, J. (gol.). Elsevier, t. 81-113

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  12. Cyhoeddwyd

    Workshop on the Celtic Seas Ecoregion Aquaculture Overview

    O'Biern, F. (gol.), Ojaveer, H. (gol.), Boyd, A., Capuzzo, E., Devine, G., Moore, H., O'Carroll, J., Dennis, J., King, J., Falconer, L., Ellis, T. & Telfor, T., 5 Hyd 2022, ICES Scientific Reports. 57 gol. Copenhagen, Cyfrol 4. 126 t. (ICES Scientific Reports; Cyfrol 4, Rhif 57).

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  13. Rhifyn Arbennig › Ymchwil › Adolygwyd gan gymheiriaid
  14. Cyhoeddwyd

    The Hominin sites and Palaeolakes Drilling Project: testing hypotheses of climate-driven human evolution and dispersal at Chew Bahir, Ethiopia

    Lamb, H., Cohen, A., Schabitz, F., Asrat, A., Bates, R., Davies, S., Deino, A., Forster, V., Grove, M., Huws, D., Junginger, A., Konrad-Schmolke, M., Lane, C., Leng, M., Mark, D., Martin-Jones, E., Pearce, N., Pearson, E., Ramsey, C., Raub, T., Rethemeyer, J., Roberts, H., Rogass, C., Trauth, M., Viehberg, F., Wagner, B. & Woldegabriel, G., 6 Meh 2016, Yn: Quaternary International. 404, Part B, t. 209 1 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynRhifyn Arbennigadolygiad gan gymheiriaid

  15. Cyhoeddwyd

    Tidal energy extraction in three-dimensional ocean models

    Goward Brown, A., Neill, S. & Lewis, M., Rhag 2017, Yn: Renewable Energy. 114, A, t. 244/257

    Allbwn ymchwil: Cyfraniad at gyfnodolynRhifyn Arbennigadolygiad gan gymheiriaid

  16. Golygyddiad › Ymchwil › Adolygwyd gan gymheiriaid
  17. Cyhoeddwyd

    Rethinking coral reef functional futures

    Williams, G. J. & Graham, N. A. J., 7 Meh 2019, Yn: Functional Ecology. 33, 6, t. 942-947

    Allbwn ymchwil: Cyfraniad at gyfnodolynGolygyddiadadolygiad gan gymheiriaid

  18. Cyhoeddwyd

    Wastewater-Based Epidemiology: Global Collaborative to Maximize Contributions in the Fight Against COVID-19

    Bivins, A., North, D., Ahmad, A., Ahmed, W., Alm, E., Been, F., Bhattacharya, P., Bijlsma, L., Boehm, A. B., Brown, J., Buttiglieri, G., Calabro, V., Carducci, A., Castiglioni, S., Gurol, Z. C., Chakraborty, S., Costa, F., Curcio, S., de los Reyes, F. L. . III., Vela, J. D., Farkas, K., Fernandez-Casi, X., Gerba, C., Gerrity, D., Girones, R., Gonzalez, R., Haramoto, E., Harris, A., Holden, P. A., Islam, M. T., Jones, D. L., Kasprzyk-Hordern, B., Kitajima, M., Kotlarz, N., Kumar, M., Kuroda, K., La Rosa, G., Malpei, F., Mautus, M., McLellan, S. L., Medema, G., Meschke, J. S., Mueller, J., Newton, R. J., Nilsson, D., Noble, R. T., van Nuijs, A., Peccia, J., Perkins, T. A., Pickering, A. J., Rose, J., Sanchez, G., Smith, A., Stadler, L., Stauber, C., Thomas, K., van der Voorn, T., Wigginton, K., Zhu, K. & Bibby, K., 7 Gorff 2020, Yn: Environmental Science and Technology. 54, 13, t. 7754-7757

    Allbwn ymchwil: Cyfraniad at gyfnodolynGolygyddiadadolygiad gan gymheiriaid

  19. Sylw/Dadl › Ymchwil › Adolygwyd gan gymheiriaid
  20. Cyhoeddwyd

    Comment on: “Is ‘re-mobilisation’ nature restoration or nature destruction? A commentary”, by Delgado-Fernandez et al.

    Austin, M. & Walker-Springett, G., 13 Ion 2021, Yn: Journal of Coastal Conservation. 25, 1, 10.

    Allbwn ymchwil: Cyfraniad at gyfnodolynSylw/Dadladolygiad gan gymheiriaid

  21. Cyhoeddwyd

    Important Shark Areas: rationale and need

    Moore, A. & Fowler, S., 1 Ebr 2022, Yn: Aquatic Conservation: Marine and Freshwater Ecosystems. 32, 4, t. 710-711 2 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynSylw/Dadladolygiad gan gymheiriaid

  22. Llythyr › Ymchwil › Adolygwyd gan gymheiriaid
  23. Cyhoeddwyd

    Artificial skyglow disrupts celestial migration at night

    Torres, D., Tidau, S., Jenkins, S. & Davies, T., 22 Meh 2020, Yn: Current Biology. 30, 12, t. PR696-R697

    Allbwn ymchwil: Cyfraniad at gyfnodolynLlythyradolygiad gan gymheiriaid

  24. Cyhoeddwyd

    Eco-imperialism

    Sheppard, C. & Turner, J., 21 Maw 2009, Yn: New Scientist. 201, 2700, t. 22-22

    Allbwn ymchwil: Cyfraniad at gyfnodolynLlythyradolygiad gan gymheiriaid

  25. Cyhoeddwyd

    Ocean community warming responses explained by thermal affinities and temperature gradients

    Burrows, M. T., Bates, A. E., Costello, M. J., Edwards, M., Edgar, G. J., Fox, C. J., Halpern, B. S., Hiddink, J. G., Pinsky, M. L., Batt, R. D., Molinos, J. G., Payne, B., Schoeman, D., Stuart-Smith, R. D. & Poloczanska, E. S., 25 Tach 2019, Yn: Nature Climate Change. 9, 12, t. 959-963

    Allbwn ymchwil: Cyfraniad at gyfnodolynLlythyradolygiad gan gymheiriaid

  26. Cyhoeddwyd

    Selective foraging behavior of seabirds in small-scale slicks

    Lieber, L., Füchtencordsjürgen, C., Hilder, R. L., Revering, P. J., Siekmann, I., Langrock, R. & Nimmo-Smith, W. A. M., Ebr 2023, Yn: Limnology and Oceanography Letters. 8, 2, t. 286-294 9 t., 10289.

    Allbwn ymchwil: Cyfraniad at gyfnodolynLlythyradolygiad gan gymheiriaid

  27. Cyhoeddwyd

    Turbulent Dissipation of Coastal Seas: Response to article: Observations of Biologically Generated Turbulence in a Coastal Inlet. Kunze, E., Dower, J.F., Beveridge, R., & Bartlett, K.P. (2007) Science 313, 5794, 1768-1770

    Rippeth, T., Gascoigne, J., Green, M., Inall, M., Palmer, M., Wiles, P. & Simpson, J., 7 Meh 2007, Yn: Science. 313, 5794

    Allbwn ymchwil: Cyfraniad at gyfnodolynLlythyradolygiad gan gymheiriaid

  28. Erthygl › Ymchwil › Adolygwyd gan gymheiriaid
  29. Wedi ei Dderbyn / Yn y wasg

    "you just look at rocks, and have beards" Perceptions of geology from the UK: a qualitative analysis from an online survey.

    Rogers, S. L., Giles, S., Dowey, N., Greene, S. E., Bhatia, R., Van Landeghem, K. & King, C., 17 Ion 2024, (Wedi ei Dderbyn / Yn y wasg) Yn: Earth Science, Systems and Society.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  30. Cyhoeddwyd

    'Heavy metal' - time to move on from semantics to pragmatics?

    Hubner, R., Astin, K. B. & Herbert, R. J., 8 Gorff 2010, Yn: Journal of Environmental Monitoring. 12, t. 1511-1514

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  31. Cyhoeddwyd

    150,000-year palaeoclimate record from northern Ethiopia supports early, multiple dispersals of modern humans from Africa

    Lamb, H., Bates, R., Bryant, C., Davies, S., Huws, D., Marshall, M. & Roberts, H., 18 Ion 2018, Yn: Scientific Reports. 8, 1077.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  32. Cyhoeddwyd

    2DV modelling of sediment transport processes over full-scale ripples in regular asymmetric oscillatory flow.

    Van Der Werf, J. J., Magar, V., Malarkey, J., Guizien, K. & O'Donoghue, T., 15 Mai 2008, Yn: Continental Shelf Research. 28, 8, t. 1040-1056

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  33. Cyhoeddwyd

    36 year trends in dissolved organic carbon export from Finnish rivers to the Baltic Sea

    Raike, A., Kortelainen, P., Mattsson, T. & Thomas, D. N., 1 Hyd 2012, Yn: Science of the Total Environment. 435, t. 188-201

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  34. Cyhoeddwyd

    A 26,000-year integrated record of marine and terrestrial environmental change off Gabon, west equatorial Africa

    Kim, S. Y., Scourse, J. D. & Marret, F., 1 Ion 2010, Yn: Palaeogeography, Palaeoclimatology, Palaeoecology. 297, t. 428-438

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  35. Cyhoeddwyd

    A 30,000 yr record of land–ocean interaction in the eastern Gulf of Guinea

    Marret, F., Kim, S. Y. & Scourse, J. D., 1 Gorff 2013, Yn: Quarternary Research. 80, 1, t. 1-8

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  36. Cyhoeddwyd

    A Comparison of Stochastic and Deterministic Downscaling in Eddy Resolving Ocean Modelling: The Lakshadweep Sea Case Study

    Shapiro, G., Ondina, J., Poovadiyil, S. & Tu, J., 6 Chwef 2023, Yn: Journal of Marine Science and Engineering . 11, 2

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  37. Cyhoeddwyd

    A Comparison of Tidal Conversion Parameterizations for Tidal Models

    Green, J. A. & Nycander, J., 1 Ion 2013, Yn: Journal of Physical Oceanography. 43, 1, t. 104-119

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  38. Cyhoeddwyd

    A Comprehensive Assessment of Climate Change and Coastal Inundation through Satellite-Derived Datasets: A Case Study of Sabang Island, Indonesia

    Kantamaneni, K., Christie, D., Lyddon, C., Huang, P., Nizar, M., Balasubramani, K., Ravichandran, V., Prasad, K. A., Pushparaj, R. R. B., Robins, P. & Panneer, S., 15 Meh 2022, Yn: Remote Sensing. 14, 12, 2857.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  39. Cyhoeddwyd

    A Gel Filtration-Based Method for the Purification of Infectious Rotavirus Particles for Environmental Research Applications

    Farkas, K., Pang, L., Lin, S., Williamson, W., Easingwood, R., Fredericks, R., Jaffer, M. A. & Varsani, A., 1 Rhag 2013, Yn: Food and Environmental Virology. 5, 4, t. 231-235

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  40. Cyhoeddwyd

    A Heart That Beats for 500 Years: Age-Related Changes in Cardiac Proteasome Activity, Oxidative Protein Damage and Expression of Heat Shock Proteins, Inflammatory Factors, and Mitochondrial Complexes in Arctica islandica, the Longest-Living Noncolonial Animal

    Sosnowska, D., Richardson, C. A., Sonntag, W. E., Csiszar, A., Ungvari, Z. & Ridgway, I. D., 17 Rhag 2013, Yn: Journals of Gerontology, Series A. 69, 12, t. 1448-1461

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  41. Cyhoeddwyd

    A Late Pleistocene channelized subglacial meltwater system on the Atlantic continental shelf south of Ireland

    Giglio, C., Benetti, S., Sacchetti, F., Lockhart, E. A., Clarke, J. H., Plets, R., Van Landeghem, K., Ó Cofaigh, C., Scourse, J. & Dunlop, P., Ion 2022, Yn: Boreas. 51, 1, t. 118-135

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  42. Cyhoeddwyd

    A Multi-disciplinary Approach to the Archaeological Investigation of a Bedrock-Dominated Shallow-Marine Landscape: An example from the Bay of Firth, Orkney, UK

    Bates, M., Nayling, N., Bates, R., Dawson, S., Huws, D. & wickham-jones, C. R., 2 Hyd 2012, Yn: The International Journal of Nautical Archaeology. 42, 1, t. 24 20 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  43. Cyhoeddwyd

    A PRESCRIPTIVE MODEL OF STRATIFICATION INDUCED BY FRESH-WATER RUNOFF

    Simpson, J., Sharples, J. & Rippeth, T., 1 Gorff 1991, Yn: Estuarine, Coastal and Shelf Science. 33, 1, t. 23-35

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  44. Cyhoeddwyd

    A Path to a Sustainable Trawl Fishery in Southeast Asia

    Suuronen, P., Pitcher, C. R., McConnaughey, R. A., Kaiser, M., Hiddink, J. G. & Hilborn, R., 1 Hyd 2020, Yn: Reviews in Fisheries Science & Aquaculture. 28, 4, t. 499-517 19 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  45. Cyhoeddwyd

    A Self-Contained Subsea Platform for Acoustic Monitoring of the Environment Around Marine Renewable Energy Devices-Field Deployments at Wave and Tidal Energy Sites in Orkney, Scotland

    Williamson, B. J., Blondel, P., Armstrong, E., Bell, P. S., Hall, C., Waggitt, J. J. & Scott, B. E., Ion 2016, Yn: IEEE JOURNAL OF OCEANIC ENGINEERING. 41, 1, t. 67-81

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  46. Cyhoeddwyd

    A behavior-based modeling approach to reducing shorebird-shellfish conflicts

    Caldow, R. W., Beadman, H. A., McGrorty, S., Stillman, R. A., Goss-Custard, J. D., Durell, S. E., West, A. D., Kaiser, M. J., Mould, K. & Wilson, A., 1 Hyd 2004, Yn: Ecological Applications. 14, 5, t. 1411-1427

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  47. Cyhoeddwyd

    A checklist of the corals of the island state of Rodrigues, Mauritius.

    Fenner, D., Clark, T. H., Turner, J. R. & Chapman, B., 1 Rhag 2004, Yn: Journal of Natural History. 38, 23-24, t. 3091-3102

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  48. Cyhoeddwyd

    A classification system for global wave energy resources based on multivariate clustering

    Fairley, I., Lewis, M., Robertson, B., Hermer, M., Masters, I., Horrillo-Caraballo, J., Karunarathna, H. & Reeve, D. E., 15 Maw 2020, Yn: Applied Energy. 262, 114515.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  49. Cyhoeddwyd

    A comparison of VMS and AIS data: the effect of data coverage and vessel position recording frequency on estimates of fishing footprints

    Shepperson, J., Hintzen, N. T., Szostek, C., Bell, E., Murray, L. & Kaiser, M., 1 Mai 2018, Yn: ICES Journal of Marine Science. 75, 3, t. 988-998

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  50. Cyhoeddwyd

    A comparison of population differentiation in two shore crab species with contrasting distribution along the Portuguese coast, using two morphological methodologies.

    Silva, I. C., Hawkins, S. J. & Paula, J., 27 Awst 2009, Yn: Marine and Freshwater Research. 60, 8, t. 833-844

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  51. Cyhoeddwyd

    A comparison of precipitation and filtration-based SARS-CoV-2 recovery methods and the influence of temperature, turbidity, and surfactant load in urban wastewater

    Kevill, J. L., Pellett, C., Farkas, K., Brown, M. R., Bassano, I., Denise, H., McDonald, J. E., Malham, S. K., Porter, J., Warren, J., Evens, N. P., Paterson, S., Singer, A. C. & Jones, D. L., 20 Chwef 2022, Yn: Science of the Total Environment. 808, 151916.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  52. Cyhoeddwyd

    A comparison of the diel variability in epilimnetic temperature for five lakes in the English Lake District

    Woolway, R. I., Jones, I. D., Feuchtmayr, H. & Maberly, S. C., 20 Ebr 2015, Yn: INLAND WATERS. 5, 2, t. 139-154

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  53. Cyhoeddwyd

    A comparison of two techniques for the rapid assessment of marine habitat complexity

    Lambert, G. I., Jennings, S., Hinz, H., Murray, L. G., Lael, P., Kaiser, M. J. & Hiddink, J. G., Maw 2013, Yn: Methods in Ecology and Evolution. 4, 3, t. 226-235

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  54. Cyhoeddwyd

    A continental scale evaluation of the role of limpet grazing on rocky shores.

    Coleman, R. A., Underwood, A. J., Benedetti-Cecchi, L., Aberg, P., Arena, F., Arrontes, J., Castro, J., Hartnoll, R. G., Jenkins, S. R., Paula, J., Della Santina, P. & Hawkins, S. J., 1 Maw 2006, Yn: Oecologia. 147, 3, t. 556-564

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  55. Cyhoeddwyd

    A coupled tide-wave model for the NW European shelf seas

    Hashemi, R. M., Neill, S. P. & Davies, A. G., 14 Awst 2014, Yn: Geophysical and Astrophysical Fluid Dynamics.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  56. Cyhoeddwyd

    A critical review of the glaciomarine model for Irish sea deglaciation: evidence from southern Britain, the Celtic shelf and adjacent continental slope.

    Scourse, J. D. & Furze, M. F., 1 Gorff 2001, Yn: Quaternary Science. 16, 5, t. 419-434

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid