Ysgol Gwyddorau Amgylcheddol a Naturiol

  1. Cyhoeddwyd

    Natural capital and ecosystem services, developing an appropriate soils framework as a basis for valuation

    Robinson, D. A., Hockley, N., Cooper, D. M., Emmett, B. A., Keith, A. M., Lebron, I., Reynolds, B., Tipping, E., Tye, A. M., Watts, C. W., Whalley, W. R., Black, H. I., Warren, G. P. & Robinson, J. S., 15 Maw 2013, Yn: Soil Biology and Biochemistry. 57, t. 1023-1033

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  2. Cyhoeddwyd

    Natural History Notes: Crotalus scutulatus (Mohave rattlesnake). Maximum size.

    Mrinalini, [. V., Hicks, J. J. & Wüster, W., 1 Meh 2015, Yn: Herpetological Review. 46, 2, t. 271 1 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  3. Cyhoeddwyd

    Natural History Notes. Scolecophis atrocinctus (Black-banded Snake). Reproduction / Combat Behaviour

    Chernov, E., Hoffmann, E. P. & Wüster, W., 1 Medi 2020, Yn: Herpetological Review. 51, 3, t. 628-629 2 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  4. Cyhoeddwyd

    Natural History Notes. Naja kaouthia (monocled cobra). Behavior / Spitting.

    Santra, V. & Wüster, W., 1 Meh 2017, Yn: Herpetological Review. 48, 2, t. 455-456 2 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  5. Cyhoeddwyd

    Natural Herbicides from a Renewable Feedstock

    Wright, S., Tverezovskiy, V., Williamson, C., Braganca, R. & Gould, M., 4 Meh 2016. 1 t.

    Allbwn ymchwil: Cyfraniad at gynhadleddPapuradolygiad gan gymheiriaid

  6. Cyhoeddwyd

    Natural Capital, Ecosystem Services, and Soil Change: Why Soil Science Must Embrace an Ecosystems Approach

    Robinson, D. A., Hockley, N., Dominati, E., Lebron, I., Scow, K. M., Reynolds, B., Emmett, B. A., Keith, A. M., de Jong, L. W., Schjønning, P., Moldrup, P., Jones, S. B. & Tuller, M., 1 Chwef 2012, Yn: Vadose Zone Journal. 11, 1

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  7. Cyhoeddwyd

    National-scale antimicrobial resistance surveillance in wastewater: A comparative analysis of HT qPCR and metagenomic approaches

    Knight, M. E., Webster, G., Perry, W. B., Baldwin, A., Rushton, L., Pass, D. A., Cross, G., Durance, I., Muziasari, W., Kille, P., Farkas, K., Weightman, A. J. & Jones, D. L., 15 Medi 2024, Yn: Water research. 262, t. 121989

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  8. Cyhoeddwyd

    National scale mapping of supply and demand for recreational ecosystem services

    Hooftman, D., Ridding, L., Redhead, J. & Willcock, S., Hyd 2023, Yn: Ecological Indicators. 154, 20 t., 110779.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  9. Cyhoeddwyd

    Nanosecure: Advanced nanotechnological detection and detoxification of harmful airborne substances for improved public security

    Barrault, J., Bedel, L., Charikane, E., Gunnarsen, L., Gwenin, C. D., Jones, J., Lieberzeit, P., Rowley, A., Soto, T., Thollon, S., Thorstensen, B., Traberg-Borup, S. & Wright, N., 1 Hyd 2013, Yn: L'Actualité Chimique. 378-379, t. 27-34

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  10. Cyhoeddwyd

    Nanopore environmental DNA sequencing of catch water for estimating species composition in demersal bottom trawl fisheries

    Maggini, S., Jacobsen, M. W., Urban, P., Hansen, B. K., Kielgast, J., Bekkevold, D., Jardim, E., Martinsohn, J. T., Carvalho, G., Nielsen, E. E. & Papadopulos, A. S. T., 20 Mai 2024, Yn: Environmental DNA. 6, 3, e555.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  11. Cyhoeddwyd

    Nanohaloarchaea as beneficiaries of xylan degradation by haloarchaea

    La Cono, V., Messina, E., Reva, O., Smedile, F., La Spada, G., Crisafi, F., Marturano, L., Miguez, N., Ferrer, M., Selivanova, E. A., Golyshina, O., Golyshin, P., Rohde, M., Krupovic, M., Merkel, A. Y., Sorokin, D. Y., Hallsworth, J. E. & Yakimov, M., Medi 2023, Yn: Microbial Biotechnology. 16, 9, t. 1803-1822 20 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  12. Cyhoeddwyd

    Nano-Sized and Filterable Bacteria and Archaea: Biodiversity and Function

    Ghuneim, L.-A., Jones, D. L., Golyshin, P. & Golyshina, O., 21 Awst 2018, Yn: Frontiers in Microbiology. 9, 1971.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  13. Cyhoeddwyd

    Naming and recognition of species in participatory biodiversity inventory.

    Wong, J., Lysinge, R., Kenfack, D., Healey, J. R. & Hall, J. B., 7 Ion 2002, t. 8.

    Allbwn ymchwil: Cyfraniad at gynhadleddPapur

  14. Cyhoeddwyd

    Naming and recognition of species in participatory biodiversity inventory.

    Wong, J., Lysinge, R., Kenfack, D., Healey, J. R., Hall, J. B. & Lawrence, A., 1 Ion 2002

    Allbwn ymchwil: Ffurf annhestunolSafe Gwe / Cyhoeddiad Gwe

  15. Cyhoeddwyd

    Naja naja Reproduction

    Kuttalam, S. R., Owens, J. B., Das, B., Koley, A. & Santra, V., 2 Mai 2023, Yn: Herpetological Review. 54, 1, t. 141 1 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  16. Cyhoeddwyd

    NMR study of hydroxy protons of di- and trimannosides, substructures of Man-9

    Hakkarainen, B., Kenne, L., Lahmann, M., Oscarson, S. & Sandstrom, C., 1 Rhag 2007, Yn: Magnetic Resonance in Chemistry. 45, 12, t. 1076-1080

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  17. Cyhoeddwyd

    NEW BIS ESTERS OF IVY SAPOGENINS FOR RUMINANTS

    Al-Dulayymi, J. (Dyfeisiwr), Bouillon, M. (Dyfeisiwr), Braganca, R. (Dyfeisiwr), Preskett, D. (Dyfeisiwr) & Lahmann, M. (Dyfeisiwr), 10 Hyd 2018, Rhif y patent WO/2016/193309

    Allbwn ymchwil: Patent

  18. Cyhoeddwyd

    N2 fixation and cycling in Alnus glutinosa, Betula pendula and Fagus sylvatica woodland exposed to free air CO2 enrichment

    Millett, J., Godbold, D., Smith, A. R. & Grant, H., 18 Rhag 2011, Yn: Oecologia. 169, 2, t. 541-52 12 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  19. Cyhoeddwyd

    N-carbamate protected amino acid derived guanidine organocatalysts

    Al-Taie, Z. S., Anderson, J. M., Bischoff, L., Christensen, J., Coles, S. J., Froom, R., Gibbard, M. E., Jones, L. F., de Kleijne, F. F. J., Murphy, P. & Thompson, E., 4 Meh 2021, Yn: Tetrahedron. 89, 132093.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  20. Cyhoeddwyd

    N-Acetylglucosaminidase activities in wetlands: a global survey

    Kang, H. J., Freeman, C., Park, S. S. & Chun, J., 1 Ion 2005, Yn: Hydrobiologia. 532, t. 103-110

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  21. Cyhoeddwyd

    N-2 Fixation in Feather Mosses is a Sensitive Indicator of N Deposition in Boreal Forests

    Ackermann, K., Zackrisson, O., Rousk, J., Jones, D. L. & DeLuca, T. H., Medi 2012, Yn: Ecosystems. 15, 6, t. 986-998

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  22. Cyhoeddwyd

    N-15-amino sugar stable isotope probing (N-15-SIP) to trace the assimilation of fertiliser-N by soil bacterial and fungal communities

    Reay, M. K., Charteris, A. F., Jones, D. L. & Evershed, R. P., Tach 2019, Yn: Soil Biology and Biochemistry. 138, 107599.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  23. Cyhoeddwyd

    Mycorrhizas.

    Godbold, D. L., Sharrock, R. A., Schroth, G. (Golygydd) & Sinclair, F. L., 1 Ion 2003, Trees: crops and soil fertility: concepts and research methods. 2003 gol. CAB International, t. 271-287

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  24. Cyhoeddwyd

    Mycorrhizas improve the absorption of non-available phosphorus by the green manure Tithonia diversifolia in poor soils

    Scrase, F. M., Sinclair, F. L., Farrar, J. F., Pavinato, P. S. & Jones, D. L., Maw 2019, Yn: Rhizosphere. 9, t. 27-33 7 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  25. Cyhoeddwyd

    Mycorrhizal hyphal turnover as a dominant process for carbon input into soil organic matter.

    Godbold, D. L., Hoosbeek, M. R., Lukac, M., Cotrufo, M. F., Janssens, I. A., Ceulemans, R., Polle, A., Velthorst, E. J., Scarascia-Mugnozza, G., De Angelis, P., Miglietta, F. & Peressotti, A., 1 Maw 2006, Yn: Plant and Soil. 281, 1-2, t. 15-24

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  26. Cyhoeddwyd

    Mycorrhizae.

    Godbold, D. L., Burley, J. (Golygydd), Evans, J. (Golygydd) & Youngquist, J. A. (Golygydd), 1 Ion 2004, Encyclopedia of forest sciences. 2004 gol. Elsevier, t. 1663-1640

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  27. Cyhoeddwyd

    Mycolyl arabino glycerols from synthetic mycolic acids

    Mohammed, M. O., Baird, M. S. & Al-Dulayymi, J., 16 Ion 2015, Yn: Tetrahedron Letters. 56, 23, t. 3268–3272

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  28. Cyhoeddwyd

    Mycolates of Mycobacterium tuberculosis modulate the flow of cholesterol for bacillary proliferation in murine macrophages

    Vermeulen, I., Baird, M., Al-Dulayymi, J., Smet, M., Verschoor, J. & Grooten, J., 1 Ebr 2017, Yn: Journal of Lipid Research. 58, 4, t. 709-718 9 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  29. 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

  30. 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

  31. Cyhoeddwyd

    My Woodland Heritage

    Walmsley, J., 1 Medi 2024, Woodland Heritage Annual Journal 2024, 2024, t. 56-59 4 t.

    Allbwn ymchwil: Cyfraniad at gyhoeddiad arbenigolErthygl

  32. 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

  33. 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

  34. 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

  35. 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

  36. Cyhoeddwyd

    Multivariate analysis of infrared spectra for the prediction of the mechanical performance and dimensional stability of thermally modified wood.

    Gonzalez-Pena, M. & Hale, M. D., 1 Ion 2007, 2007 gol. Unknown.

    Allbwn ymchwil: Llyfr/AdroddiadAdroddiad Comisiwn

  37. 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

  38. 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

  39. 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

  40. 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

  41. 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

  42. 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

  43. 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

  44. Cyhoeddwyd

    Multimodal Capstone Project, Biosciences

    Winder, I. C., 18 Ebr 2024, Multimodal Learning: A Practitioner Guide. Advance HE, t. 25-26 2 t.

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddCyfraniad Pennod Aralladolygiad gan gymheiriaid

  45. 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

  46. 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

  47. 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

  48. 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

  49. 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

  50. 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