Ysgol Gwyddorau Amgylcheddol a Naturiol

  1. Cyhoeddwyd

    Estimating the prevalence of food risk increasing behaviours in UK kitchens

    Jones, A. K., Cross, P., Burton, M., Millman, C., O’Brien, S. J. & Rigby, D., 28 Meh 2017, Yn: PLoS ONE. 12, 6, t. e0175816

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  2. Cyhoeddwyd

    Estimating the potential of beekeeping to alleviate household poverty in rural Uganda

    Amulen, D. R., D’Haese, M., D'Haene, E., Okwee Acai, J., Agea, J. G., Smagghe, G. & Cross, P., 27 Maw 2019, Yn: PLoS ONE. 14, 3, t. e0214113

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  3. Cyhoeddwyd

    Estimating the population density of the Asian Tapir Tapirus indicus from a selectively logged forest in Peninsular Malaysia

    Rayan, D. M., Mohamad, S. W., Dorward, L., S.A., A., Clements, R. B., Wong, C., Traeholt, C. & Magintan, D., Rhag 2012, Yn: Integrative Zoology. 7, 4, t. 373-380

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  4. Cyhoeddwyd

    Estimating the energetic cost of fighting in shore crabs by noninvasive monitoring of heartbeat rate

    Rovero, F., Hughes, R. N., Whiteley, N. & Chelazzi, G., 1 Ebr 2000, Yn: Animal Behaviour. 59, 4, t. 705-713

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  5. Cyhoeddwyd

    Estimating the dwarfing rate of an extinct Sicilian elephant

    Baleka, S., Herridge, V. L., Catalano, G., Lister, A. M., Dickinson, M. R., Di Patti, C., Barlow, A., Penkman, K., Hofreiter, M. & Paijmans, J., 23 Awst 2021, Yn: Current Biology.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  6. Cyhoeddwyd

    Estimating the component of soil respiration not dependent on living plant roots: comparison of the indirect y-intercept regression approach and direct bare plot approach.

    Koerber, G. R., Hill, P. W., Edwards-Jones, G. & Jones, D. L., 1 Hyd 2010, Yn: Soil Biology and Biochemistry. 42, 10, t. 1835-1841

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  7. Cyhoeddwyd

    Estimating the Extent of CITES Noncompliance among Traders and End-Consumers: Lessons from the Global Orchid Trade

    Hindsley, A., Nuno, A., Ridout, M. & St John, F. A. V., Medi 2017, Yn: Conservation Letters. 10, 5, t. 602-609

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  8. Cyhoeddwyd

    Estimating rates of gene flow in endemic butterfly races: the effect of metapopulation dynamics.

    Taneyhill, D., Mallet, J., Wynne, I., Burke, S., Pullin, A. S., Wilson, R. J., Butlin, R. K., Hatcher, M. J., Shorrocks, B., Thomas, C. D., Hails, R. (gol.), Beringer, J. (gol.) & Godfray, H. C. (gol.), 1 Ion 2001, Genes in the environment. 2001 gol. Cambridge University Press, t. 3-25

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennod

  9. Cyhoeddwyd

    Estimating greenhouse gases emissions from horticultural peat soils using a DNDC modelling approach

    Taft, H. E., Cross, P. A., Hastings, A., Yeluripati, J. & Jones, D. L., 1 Maw 2019, Yn: Journal of Environmental Management. 233, t. 681-694 14 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  10. Cyhoeddwyd

    Estimating genetic variability in non-model taxa: a general procedure for discriminating sequence errors from actual variation.

    Dawson, K., Thorpe, R. S. & Malhotra, A., 6 Rhag 2010, Yn: PLoS ONE. 15, 12, t. e15204

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  11. Cyhoeddwyd

    Estimating feed intake of browse species in biodiverse silvopastoral systems.

    Cajas-Giron, Y. S., Mayes, R. W. & Sinclair, F. L., 2 Ebr 2001, t. 280-284.

    Allbwn ymchwil: Cyfraniad at gynhadleddPapur

  12. Cyhoeddwyd

    Estimating charcoal content in forest mineral soils.

    Kurth, V. J., MacKenzie, M. D. & DeLuca, T. H., 31 Rhag 2006, Yn: Geoderma. 137, 1-2, t. 135-139

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  13. Cyhoeddwyd

    Establishment of local wastewater-based surveillance programmes in response to the spread and infection of COVID-19-case studies from South Africa, the Netherlands, Turkey and England

    Tlhagale, M., Liphadzi, S., Bhagwan, J., Naidoo, V., Jonas, K., van Vuuren, L., Medema, G., Andrews, L., Been, F., Ferreira, M. L., Saatci, A. M., Kocamemi, B. A., Hassard, F., Singer, A. C., Bunce, J. T., Grimsley, J. M. S., Brown, M. & Jones, D. L., 1 Chwef 2022, Yn: Journal of Water and Health. 20, 2, t. 287-299

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  14. Cyhoeddwyd

    Establishment of background water quality conditions in the Great Zab River catchment: influence of geogenic and anthropogenic controls on developing a baseline for water quality assessment and resource management

    Ismaiel, I. A., Bird, G., McDonald, M., Perkins, W. & Jones, T., Ion 2018, Yn: Environmental Earth Sciences. 77, 2, 50.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  15. Cyhoeddwyd

    Establishment of Clethra occidentalis (L.) Kuntze on stems of the tree-fern Cyathea pubescens Mett. ex Kuhn in a Jamaican montane rainforest

    Newton, A. C. & Healey, J., 1989, Yn: Journal of Tropical Ecology. 5, 4, t. 441-445

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  16. Cyhoeddwyd

    Establishment and expansion of Lake Malawi rock fish populations after a dramatic Late Pleistocene lake level rise.

    Genner, M. J., Knight, M. E., Haeslers, M. P. & Turner, G. F., 1 Ion 2010, Yn: Molecular Ecology. 19, 1, t. 170-182

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  17. Cyhoeddwyd

    Essentials in the use of mycolic acid biomarkers for tuberculosis detection: response to “High-throughput mass spectrometric analysis of 1400-year-old mycolic acids as biomarkers for ancient tuberculosis infection” by Mark et al., 2010

    Minnikin, D. E., Lee, O. Y., Pitts, M., Baird, M. S. & Besra, G. S., 1 Hyd 2010, Yn: Journal of Archaeological Science. 37, 10, t. 2407-2412

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  18. Cyhoeddwyd

    Escherichia coli O157: comparing awareness of rural residents and visitors in livestock farming areas

    Jones, C. D., Hunter, C., Williams, A. P., Strachan, N. J. & Cross, P., 7 Ion 2011, Yn: Epidemiology and Infection. 139, 10, t. 1522-1530

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  19. Cyhoeddwyd

    Escherichia coli O157 survival following the surface and sub-surface application of human pathogen contaminated organic waste to soil.

    Avery, L. M., Hill, P. W., Killham, K. & Jones, D. L., 1 Rhag 2004, Yn: Soil Biology and Biochemistry. 36, 12, t. 2101-2103

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  20. Cyhoeddwyd

    Equilibrium moisture content and moisture exclusion efficiency of Acetylated Rattan (Calamus Manan)

    Hisham, H. N., Hale, M. D. & Norasikin, A. L., 1 Ion 2014, Yn: Journal of Tropical Forest Science. 26, 1, t. 32-40

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  21. Cyhoeddwyd

    Epoxide rearrangements using dilithiated aminoalcohols as chiral bases.

    Brookes, P. C., Milne, D. J., Murphy, P. J. & Spolaore, B., 3 Meh 2002, Yn: Tetrahedron. 58, 23, t. 4675-4680

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  22. Cyhoeddwyd

    Epizoic Barnacles Act as Pathogen Reservoirs on Shellfish Beds

    Clements, K., Gimenez Noya, L., Jones, D., Wilson, J. & Malham, S. K., Awst 2013, Yn: Journal of Shellfish Research. 32, 2, t. 533-538

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  23. Cyhoeddwyd

    Epistatic regulation of growth in Atlantic salmon revealed: a QTL study performed on the domesticated-wild interface

    Besnier, F., Solberg, M. F., Harvey, A., Carvalho, G., Bekkevold, D., Taylor, M. I., Creer, S., Nielsen, E. E., Skaala, O., Ayllon, F., Dahle, G. & Glover, K. A., 7 Chwef 2020, Yn: BMC Genetics. 21, 1, 13.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  24. Cyhoeddwyd

    Epigenetic divergence during early stages of speciation in an African crater lake cichlid fish

    Vernaz, G., Hudson, A. G., Santos, M. E., Fischer, B., Carruthers, M., Shechonge, A. H., Gabagambi, N. P., Tyers, A. M., Ngatunga, B. P., Malinsky, M., Durbin, R., Turner, G. F., Genner, M. J. & Miska, E. A., Rhag 2022, Yn: Nature Ecology and Evolution. 6, 12, t. 1940-1951 12 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  25. Cyhoeddwyd

    Enzymes from Extreme Environments

    Cowan, D. A., Kirby, B. B., Ferrer, M., Guazzaroni, M-E., Golyshina, O. & Golyshin, P., 25 Maw 2010, Manual of Industrial Microbiology and Biotechnology, 3rd Ed. ASM Press, t. 43-61

    Allbwn ymchwil: Pennod mewn Llyfr/Adroddiad/Trafodion CynhadleddPennodadolygiad gan gymheiriaid

  26. Cyhoeddwyd

    Enzymes for consumer products to achieve climate neutrality

    Molina-Espeja, P., Sanz-Aparicio, J., Golyshin, P., Robles-Martin, A., Guallar, V., Beltrametti, F., Muller, M., Yakimov, M., Modregger, J., van Logchem, M., Corvini, P., Shahgaldian, P., Degering, C., Wieland, S., Timm, A., de Carvalho, C. C. C. R., Re, I., Daniotti, S., Thies, S., Jaeger, K-E., Chow, J., Streit, W. R., Lottenbach, R., Rosch, R., Ansari, N. & Ferrer, M., 29 Ebr 2023, Yn: Oxford Open Climate Change. 3, 1, kgad003.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygl adolyguadolygiad gan gymheiriaid

  27. Cyhoeddwyd

    Enzyme adaptation to habitat thermal legacy shapes the thermal plasticity of marine microbiomes

    Marasco, R., Fusi, M., Coscolín, C., Borozzi, A., Almendral, D., Bargiela, R., Gohlke neé Nutschel, C., Dittrich, J., Gohlke, H., Matesanz, R., Sanchez-Carrillo, S., Mapelli, F., Chernikova, T., Golyshin, P., Ferrer, M. & Daffonchio, D., 24 Chwef 2023, Yn: Nature Communications. 14, 1, 1045.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  28. Cyhoeddwyd

    Envisioning the future with 'compassionate conservation': An ominous projection for native wildlife and biodiversity

    Callen, A., Hayward, M. W., Klop-Toker, K., Allen, B. L., Ballard, G., Beranek, C. T., Broekhuis, F., Bugir, C. K., Clarke, R. H., Clulow, J., Clulow, S., Daltry, J. C., Davies-Mostert, H. T., Di Blanco, Y. E., Dixon, V., Fleming, P. J. S., Howell, L. G., Kerley, G. I. H., Legge, S. M., Lenga, D. J., Major, T., Montgomery, R. A., Moseby, K., Meyer, N., Parker, D. M., Periquet, S., Read, J., Scanlon, R. J., Shuttleworth, C., Tamessar, C. T., Taylor, W. A., Tuft, K., Upton, R. M. O., Valenzuela, M., Witt, R. R. & Wuster, W., Ion 2020, Yn: Biological Conservation. 241, 108365.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  29. Cyhoeddwyd

    Environmental, Biogeographic, and Biochemical Patterns of Archaea of the Family Ferroplasmaceae

    Golyshina, O. V., 17 Meh 2011, Yn: Applied and Environmental Microbiology. 77, 15, t. 5071-5078

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygl adolyguadolygiad gan gymheiriaid

  30. Cyhoeddwyd

    Environmental tolerances of Gammarid amphipods: Lessons from myosin heavy chain genes.

    Whiteley, N. M., Rock, J., Magnay, J., Beech, S., El Haj, A. & Goldspink, G., 1 Gorff 2008, Yn: Comparative Biochemistry and Physiology A - Molecular and Integrative Physiology. 150, 3, t. S159-S160

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  31. Cyhoeddwyd

    Environmental selection on transcriptome-derived SNPs in a high gene flow marine fish, the Atlantic herring (Clupea harengus)

    De Bruyn, M., Limborg, M. T., Helyar, S. J., DeBruyn, M., Taylor, M. I., Nielson, E. E., Ogden, R., Carvalho, G. R. & Bekkevold, D., 1 Awst 2012, Yn: Molecular Ecology. 21, 15, t. 3686-3703

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  32. Cyhoeddwyd

    Environmental metabarcoding reveals heterogeneous drivers of microbial eukaryote diversity in contrasting estuarine ecosystems

    Lallias, D. S., Lallias, D., Hiddink, J. G., Fonseca, V. G., Gaspar, J. M., Sung, W., Neill, S. P., Barnes, N., Ferrero, T., Hall, N., Lambshead, P. J., Packer, M., Thomas, W. K. & Creer, S., 25 Tach 2014, Yn: The ISME Journal. 9, t. 1208-1221

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  33. Cyhoeddwyd

    Environmental manipulation treatment effects on the reactivity of water-soluble phenolics in a subalpine tundra ecosystem

    Thoss, V., Shevtsova, A. & Nilsson, M. C., 1 Ion 2004, Yn: Plant and Soil. 259, 1-2, t. 355-365

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  34. Cyhoeddwyd

    Environmental impacts of agricultural plastic film mulch: Fate, consequences, and solutions

    Ding, F., Jones, D. L., Chadwick, D. R., Kim, P. J., Jiang, R. & Flury, M., 25 Awst 2022, Yn: Science of the Total Environment. 836

    Allbwn ymchwil: Cyfraniad at gyfnodolynGolygyddiadadolygiad gan gymheiriaid

  35. Cyhoeddwyd

    Environmental factors affecting kid mortality in Shami goats.

    Omed, H., Al-Najjar, K., Salhab, S., Al-Merestani, R., Kasem, R., Al-Azzawi, W., Dawa, M., Omed, H. M. & Saatci, M., 1 Ion 2010, Yn: Kafkas Universitesi Veteriner Fakultesi Dergisi. 16, 3, t. 431-435

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  36. Cyhoeddwyd

    Environmental enrichment in captive juvenile thornback rays, Raja clavata (Linnaeus 1758)

    Greenway, E., Jones, K. & Cooke, G., Medi 2016, Yn: Applied Animal Behaviour Science. 182, t. 86-93

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  37. Cyhoeddwyd

    Environmental effects and consumer considerations of consuming lettuce in the UK winter.

    Milà i Canals, L., Hospido, A., Clift, R., Truninger, M., Hounsome, B. & Edwards-Jones, G., 1 Ion 2007.

    Allbwn ymchwil: Cyfraniad at gynhadleddPapur

  38. Cyhoeddwyd

    Environmental correlates of population differentiation in Atlantic herring

    Bekkevold, D., Aandre, C., Dahlgren, T. G., Clausen, L. A., Torstensen, E., Mosegaard, H., Carvalho, G. R., Christensen, T. B., Norlinder, E. & Ruzzante, D. E., 1 Rhag 2005, Yn: Evolution. 59, 12, t. 2656-2668

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  39. Cyhoeddwyd

    Environmental contaminants of honeybee products in Uganda detected using LC-MS/MS and GC-ECD

    Amulen, D. R., Spanoghe, P., Houbraken, M., Tamale, A., de Graaf, D. C., Cross, P. & Smagghe, G., 1 Meh 2017, Yn: PLoS ONE. 12, 6, t. e0178546

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  40. Cyhoeddwyd

    Environmental balance of the UK biogas sector: An evaluation by consequential life cycle assessment

    Styles, D., Dominguez, E. M. & Chadwick, D., 1 Awst 2016, Yn: Science of the Total Environment. 560-561, t. 241-253

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  41. Cyhoeddwyd

    Environmental assessment of small-scale vegetable farming systems in peri-urban areas of the Yangtze River delta region, China.

    Huang, B., Shi, X., Yu, D., Oborn, I., Blomback, K., Pagella, T. F., Wang, H., Sun, W. & Sinclair, F. L., 1 Maw 2006, Yn: Agriculture, Ecosystems and Environment. 112, 4, t. 391-402

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  42. Cyhoeddwyd

    Environmental and socio-economic effects on species-area relationships of sixteen plant and animal taxa

    Weissflog, A., 16 Gorff 2019.

    Allbwn ymchwil: Cyfraniad at gynhadleddPapur

  43. Cyhoeddwyd

    Environmental and land use consequences of replacing milk and beef with plant-based alternatives

    Porto Costa, M., Saget, S., Zimmermann, B., Petig, E., Rees, R. M., Chadwick, D., Gibbons, J., Shrestha, S., Williams, M. & Styles, D., 1 Hyd 2023, Yn: Journal of Cleaner Production. 424, 138826.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  44. Cyhoeddwyd

    Environmental DNA size sorting and degradation experiment indicates the state of Daphnia magna mitochondrial and nuclear eDNA is subcellular

    Moushomi, R., Wilgar, G., Carvalho, G., Creer, S. & Seymour, M., 29 Awst 2019, Yn: Scientific Reports. 9, 12500 (2019.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  45. Cyhoeddwyd

    Environmental DNA reveals links between abundance and composition of airborne grass pollen and respiratory health

    Rowney, F. M., Brennan, G. L., Skjoth, C. A., Griffith, G. W., McInnes, R. N., Clewlow, Y., Adams-Groom, B., Barber, A., De Vere, N., Economou, T., Hegarty, M., Hanlon, H. M., Jones, L., Kurganskiy, A., Petch, G. M., Potter, C., Munawar Rafiq, A., Warner, A., The PollerGEN Consortium, Wheeler, B. W., Osborne, N. J. & Creer, S., 10 Mai 2021, Yn: Current Biology. 31, 9, t. 1995-2003 9 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  46. Cyhoeddwyd

    Environmental DNA provides higher resolution assessment of riverine biodiversity and ecosystem function via spatio-temporal nestedness and turnover partitioning

    Seymour, M., Edwards, F. K., Cosby, B. J., Bista, I., Scarlett, P. M., Brailsford, F., Glanville, H., de Bruyn, M., Carvalho, G. & Creer, S., 3 Mai 2021, Yn: Communications Biology. 4, 1, 512.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  47. Cyhoeddwyd

    Environmental DNA monitoring of oncogenic viral shedding and genomic profiling of sea turtle fibropapillomatosis reveals unusual viral dynamics

    Farrell, J. A., Yetsko, K., Whitmore, L., Whilde, J., Eastman, C. B., Ramia, D. R., Thomas, R., Linser, P., Creer, S., Burkhalter, B., Schnitzler, C. & Duffy, D. J., 12 Mai 2021, Yn: Communications Biology. 4, 1, t. 565 1 t.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  48. Cyhoeddwyd

    Environmental DNA metabarcoding for fish diversity assessment in a macrotidal estuary: A comparison with established fish survey methods

    Gibson, T., Carvalho, G., Ellison, A., Gargiulo, E., Hatton-Ellis, T., Handley, L. L., Mariani, S., Collins, R. A., Sellers, G., Distaso, M., Zampieri, C. & Creer, S., 1 Tach 2023, Yn: Estuarine, Coastal and Shelf Science. 294, 108522.

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  49. Cyhoeddwyd

    Environmental DNA metabarcoding: transforming how we survey animal and plant communities

    Deiner, K., Bik, H. M., Machler, E., Seymour, M., Lacoursiere-Roussel, A., Altermatt, F., Creer, S., Bista, I. & Lodge, D. M., Tach 2017, Yn: Molecular Ecology Resources. 26, 21, t. 5872-5895

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid

  50. Cyhoeddwyd

    Environmental DNA for Wildlife Biology and Biodiversity Monitoring

    Evans, A. R., Bohmann, K., Evans, A., Gilbert, M. T., Carvalho, G. R., Creer, S., Knapp, M., Yu, D. W. & De Bruyn, M., 10 Mai 2014, Yn: Trends in Ecology and Evolution. 29, 6, t. 358-367

    Allbwn ymchwil: Cyfraniad at gyfnodolynErthygladolygiad gan gymheiriaid