Professor Sam Oliver
Athro mewn Gwyddorau Chwaraeon ac Ymarfer Corff
Contact info
Position: Professor
Email: s.j.oliver@bangor.ac.uk
Phone: (01248) 38 3965
Location: Room 301, George Building, Normal Site
To book a student tutorial please visit: https://outlook.office365.com/owa/calendar/SHESStaffTutorialandDropInHours@bangoroffice365.onmicrosoft.com/bookings/
- Erthygl › Ymchwil › Adolygwyd gan gymheiriaid
- Cyhoeddwyd
A comparison of heat acclimation by post-exercise hot water immersion and exercise in the heat
McIntyre, R., Mee, J., Zurawlew, M., Oliver, S., Cox, A. & Walsh, N., 1 Awst 2021, Yn: Journal of Science and Medicine in Sport. 24, 8, t. 729-734Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
A comparison of medium-term heat acclimation by post-exercise hot water immersion or exercise in the heat: Adaptations, overreaching, and thyroid hormones
McIntyre, R., Zurawlew, M., Mee, J., Walsh, N. & Oliver, S., 1 Tach 2022, Yn: American Journal of Physiology - Regulatory Integrative and Comparative Physiology. 323, 5, t. R601-R615Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
A randomized trial to assess the potential of different beverages to affect hydration status: development of a beverage hydration index
Maughan, R. J., Watson, P., Cordery, P. A. A., Walsh, N. P., Oliver, S. J., Dolci, A., Rodriguez-Sanchez, N. & Galloway, S. D. R., Maw 2016, Yn: American Journal of Clinical Nutrition. 103, 3, t. 717-723Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Anxiety and motor performance: More evidence for the effectiveness of holistic process goals as a solution to the process goal paradox
Mullen, R., Jones, E., Oliver, S. & Hardy, L., 1 Tach 2016, Yn: Psychology of Sport and Exercise. 27, November 2016, t. 142 149 t., 27.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Baroreflex Control of Sympathetic Vasomotor Activity and Resting Arterial Pressure at High Altitude: Insight from Lowlanders and Sherpa
Simpson, L., Busch, S., Oliver, S., Ainslie, P., Stembridge, M., Steinback, C. & Moore, J., 1 Mai 2019, Yn: Journal of Physiology. 597, 9, t. 2379-2390 12 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Beetroot Juice Does Not Enhance Altitude Running Performance in Well-Trained Athletes
Arnold, J. T., Oliver, S. J., Lewis-Jones, T. M., Wylie, L. J. & Macdonald, J. H., 4 Chwef 2015, Yn: Applied Physiology, Nutrition, and Metabolism.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Bilateral regional extracranial blood flow regulation to hypoxia and unilateral duplex ultrasound measurement error
Friend, A., Rogan, M., Rossetti, G., Lawley, J., Mullins, P., Sandoo, A., Macdonald, J. & Oliver, S., 1 Gorff 2021, Yn: Experimental Physiology. 106, 7, t. 1535-1548 14 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Body composition at high altitude: a randomized placebo-controlled trial of dietary carbohydrate supplementation.
Macdonald, J. H., Oliver, S. J., Hillyer, K., Sanders, S., Smith, Z., Williams, C., Yates, D., Ginnever, H., Scanlon, E., Roberts, E., Murphy, D., Lawley, J. & Chichester, E., 1 Tach 2009, Yn: American Journal of Clinical Nutrition. 90, 5, t. 1193-1202Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Carbohydrate Supplementation and Exercise Performance at High Altitude: A Randomized Controlled Trial
Oliver, S. J., Golja, P. & Macdonald, J. H., 19 Maw 2012, Yn: High Altitude Medicine and Biology. 13, 1, t. 22-31Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Control of blood pressure in the cold: Differentiation of skin and skeletal muscle vascular resistance
Mugele, H., Marume, K., Amin, S., Possnig, C., Kuhn, L., Riehl, L., Pieper, R., Schabbehard, E.-L., Oliver, S., Gagnon, D. & Lawley, J., 1 Ion 2023, Yn: Experimental Physiology. 108, 1, t. 38-49 12 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Development of a hydration index: a randomized trial to assess the potential of different beverages to affect hydration status
Oliver, S. J., Walsh, N. P., Maughan, R. J., Watson, P., Cordery, P. A., Dolci, A., Rodriguez-Sanchez, N. & Galloway, S. D., Rhag 2015, Yn: Nutricion Hospitalaria. 32, 2, t. 7Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Dietary nitrate supplementation effect on dynamic cerebral autoregulation in normoxia and acute hypoxia
Horiuchi, M., Rossetti, G. & Oliver, S., Maw 2022, Yn: Journal of Cerebral Blood Flow and Metabolism. 42, 3, t. 486-494Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Dietary nitrate supplementation increases acute mountain sickness severity and sense of effort during hypoxic exercise
Rossetti, G., Macdonald, J., Wylie, L. J., Little, S., Newton, V., Wood, B., Hawkins, K., Beddoe, R., Davies, H. E. & Oliver, S., Hyd 2017, Yn: Journal of Applied Physiology. 123, 4, t. 983-992Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Endurance running performance after 48 hours of restricted fluid and/or energy intake
Oliver, S. J., Laing, S., Wilson, S., Bilzon, J. L. & Walsh, N. P., 1 Chwef 2007, Yn: Medicine and Science in Sports and Exercise. 39, 2, t. 316-322Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Evidence for a physiological role of pulmonary arterial baroreceptors in sympathetic neural activation in healthy humans
Simpson, L., Meah, V., Steele, A., Thapamagar, S., Gasho, C., Anholm, J., Drane, A., Dawkins, T., Busch, S., Oliver, S., Lawley, J., Tymko, M., Ainslie, P., Steinback, C., Stembridge, M. & Moore, J., Maw 2020, Yn: Journal of Physiology. 598, 5, t. 955-965Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Exercise, immune function and respiratory infection: An update on the influence of training and environmental stress
Walsh, N. P. & Oliver, S. J., 8 Rhag 2015, Yn: Immunology and Cell Biology. 94, 2, t. 132-139Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Five days of tart cherry supplementation improves exercise performance in normobaric hypoxia
Horiuchi, M., Fukuoka, Y., Koyama, K. & Oliver, S., 12 Ion 2023, Yn: Nutrients. 15, 2, 388.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Global REACH 2018: Andean highlanders, chronic mountain sickness and the integrative regulation of resting blood pressure
Simpson, L., Meah, V., Steele, A., Gasho, C., Howe, C., Dawkins, T., Busch, S., Oliver, S., Moralez, G., Lawley, J., Tymko, M., Vizcardo-Galindo, G. A., Figueroa-Mujíca , R. J., Villafuerte, F., Ainslie, P., Stembridge, M., Steinback, C. & Moore, J., 1 Ion 2021, Yn: Experimental Physiology. 106, 1, t. 104-116Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Good perceived sleep quality protects against the raised risk of respiratory infection during sleep restriction in young adults
Walsh, N., Kashi, D. S., Edwards, J., Richmond, C., Oliver, S., Roberts, R., Izard, R., Jackson, S. & Greeves, J., Ion 2023, Yn: SLEEP. 46, 1, zsac222.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Greater post-exercise hypotension in healthy young untrained men after exercising in a hot compared to a temperate environment
Horiuchi, M. & Oliver, S., Hyd 2023, Yn: Journal of Thermal Biology. 117, 103683.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
High altitude impairs in vivo immunity in humans
Smith, A. D., Oliver, S. J., Macdonald, J. H., Harper Smith, A. D., Lawley, J. S., Gallagher, C. A., Di Felice, U. & Walsh, N. P., 24 Meh 2013, Yn: High Altitude Medicine and Biology. 14, 2, t. 144-149Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Wedi ei Dderbyn / Yn y wasg
Hormonal contraceptive use and physical performance, body composition, and musculoskeletal injuries during military training
O'Leary, T. J., Evans, H., Close, M.-E., Izard, R. M., Walsh, N., Coombs, C., Carswell, A., Oliver, S., Tang, J. C. Y., Fraser, W. & Greeves, J. P., 11 Hyd 2024, (Wedi ei Dderbyn / Yn y wasg) Yn: Medicine and Science in Sports and Exercise.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Hydration marker diagnostic accuracy to identify mild intracellular and extracellular dehydration
Owen, J. A., Fortes, M. B., Ur Rahman, S., Jibani, M., Walsh, N. P. & Oliver, S. J., Tach 2019, Yn: International Journal of Sport Nutrition and Exercise Metabolism. 29, 6, t. 604-611 23 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Hypoxia alters posterior cingulate cortex metabolism during a memory task: a 1H fMRS study
Rogan, M., Friend, A., Rossetti, G. M. K., Edden, R. A. E., Mikkelsen, M., Oliver, S., Macdonald, J. & Mullins, P., 15 Hyd 2022, Yn: Neuroimage. 260, 119397.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Hypoxia-induced endothelial dysfunction: Could targeting oxidative stress provide protection?
Rossetti, G., Oliver, S., Sandoo, A. & Macdonald, J., 26 Mai 2023, Yn: Experimental Physiology. 108, 8, t. 1026-1028 3 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Increased Risk of Upper Respiratory Infection in Military Recruits Who Report Sleeping Less Than 6 h per night
Wentz, L. M., Ward, M. D., Potter, C., Oliver, S. J., Jackson, S., Izard, R. M., Greeves, J. P. & Walsh, N. P., Tach 2018, Yn: Military Medicine. 183, 11-12, t. e699–e704 22 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Influence of Vitamin D Supplementation by Simulated Sunlight or Oral D3 on Respiratory Infection during Military Training
Harrison, S., Oliver, S., Kashi, D., Carswell, A., Edwards, J., Wentz, L., Roberts, R., Tang, J., Izard, R., Jackson, S., Allan, D., Rhodes, L., Fraser, W., Greeves, J. & Walsh, N., 1 Gorff 2021, Yn: Medicine and Science in Sports and Exercise. 53, 7, t. 1505-1516 12 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Influence of fluid intake on soccer performance in a temperate environment
Owen, J. A., Kehoe, S. J. & Oliver, S. J., 5 Medi 2012, Yn: Journal of Sports Sciences. 31, 1Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Influence of timing of postexercise carbohydrate-protein ingestion on selected immune indices
Costa, R. J. S., Oliver, S. J., Laing, S. J., Waiters, R., Bilzon, J. L. J. & Walsh, N. P., Awst 2009, Yn: International Journal of Sport Nutrition and Exercise Metabolism. 19, 4, t. 366-384 19 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Influence of vitamin D supplementation by sunlight or oral D3 on exercise performance
Carswell, A. T., Oliver, S. J., Wentz, L. M., Kashi, D. S., Roberts, R., Tang, J. C., Izard, R. M., Jackson, S., Allan, D., Rhodes, L. E., Fraser, W. D., Greeves, J. P. & Walsh, N. P., Rhag 2018, Yn: Medicine and Science in Sports and Exercise. 50, 12, t. 2555-2564Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Integrative crosstalk between hypoxia and the cold: old data and new opportunities
Mugele, H., Oliver, S., Gagnon, D. & Lawley, J., 1 Ion 2021, Yn: Experimental Physiology. 106, 1, t. 350-358Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Investigation of whole-brain white matter identifies altered water mobility in the pathogenesis of high-altitude headache
Lawley, J., Oliver, S. J., Mullins, P. G. & Macdonald, J. H., 1 Awst 2013, Yn: Journal of Cerebral Blood Flow and Metabolism. 33, 8, t. 1286-1294Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- E-gyhoeddi cyn argraffu
Iron status is associated with tibial structure and vitamin D metabolites in healthy young men
O'Leary, T. J., Jackson, S., Izard, R. M., Walsh, N. P., Carswell, A. T., Oliver, S., Tang, J., Fraser, W. & Greeves, J. P., 3 Meh 2024, (E-gyhoeddi cyn argraffu) Yn: Bone. 186Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Is This Elderly Patient Dehydrated? Diagnostic Accuracy of Hydration Assessment Using Physical Signs, Urine, and Saliva Markers
Fortes, M. B., Owen, J. A., Raymond-Barker, P., Bishop, C., Elghenzai, S., Oliver, S. J. & Walsh, N. P., 22 Hyd 2014, Yn: Journal of the American Medical Directors Association. 16, 3, t. 221-228Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Lets go Surfing now, everybody's learning how; attentional strategies on expert and novice surfing performance under both practice and competition conditions
Lawrence, G. P., Virian, J., Oliver, S. J. & Gottwald, V. M., 2020, Yn: European Journal of Sport Science. 20, 2, t. 229-239 11 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
MEDEX2015: Greater sea-level fitness is associated with lower sense of effort during Himalayan trekking without worse Acute Mountain Sickness
Rossetti, G., Macdonald, J., Smith, M., Jackson, A., Callender, N., Newcombe, H. K., Storey, H., Willis, S., van den Beukel, J., Woodward, J., Pollard, J., Wood, B., Newton, V., Virian, J., Haswell, O. & Oliver, S., 1 Meh 2017, Yn: High Altitude Medicine and Biology. 18, 2, t. 152-162Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Neutrophil-degranulation and lymphocyte-subset response after 48 hr of fluid and/or energy restriction
Laing, S. J., Oliver, S. J., Wilson, S., Walters, R., Bilzon, J. L. J. & Walsh, N. P., Hyd 2008, Yn: International Journal of Sport Nutrition and Exercise Metabolism. 18, 5, t. 443-56 14 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
No effect of a 30 h period of sleep deprivation on leukocyte trafficking, neutrophil degranulation and saliva IgA responses to exercise.
Laing, S., Costa, R. J., Cartner, L., Oliver, S. J., Laing, S. J., Walters, R., Bilzon, J. L. & Walsh, N. P., 1 Chwef 2009, Yn: European Journal of Applied Physiology. 105, 3, t. 499-504Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Normobaric hypoxia and symptoms of acute mountain sickness: Elevated brain volume and intracranial hypertension
Lawley, J. S., Alperin, N., Bagci, A. M., Lee, S. H., Mullins, P. G., Oliver, S. J. & Macdonald, J. H., 20 Mai 2014, Yn: Annals of Neurology. 75, 6, t. 890-898Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
One night of sleep deprivation decreases treadmill endurance performance.
Laing, S., Oliver, S. J., Costa, R. J., Laing, S. J., Bilzon, J. L. & Walsh, N. P., 1 Medi 2009, Yn: European Journal of Applied Physiology. 107, 2, t. 155-161Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Optic Nerve Sheath Diameter Is Not Related to High Altitude Headache: A Randomized Controlled Trial
Lawley, J. S., Oliver, S. J., Mullins, P. G., Morris, D., Junglee, N. A., Jelleyman, C. & Macdonald, J. H., 1 Medi 2012, Yn: High Altitude Medicine and Biology. 13, 3, t. 193-199Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Physiological and Psychological Illness Symptoms at High Altitude and Their Relationship With Acute Mountain Sickness: A Prospective Cohort Study
Hardy, L. J., Arthur, C. A., Roberts, R. J., Oliver, S. J., Sanders, S. J., Williams, C. J., Smith, Z. A., Lloyd-Davies E.*, [. V., Roberts, R., Arthur, C., Hardy, L. & Macdonald, J. H., 1 Gorff 2012, Yn: Journal of Travel Medicine. 19, 4, t. 210-219Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Portable prehospital methods to treat near-hypothermic shivering cold casualties
Raymond-Barker, P., Dolci, A., Oliver, S. J., Brierley, J. L., Raymond-Barker, P. C., Doci, A. & Walsh, N. P., 1 Maw 2016, Yn: Wilderness and Environmental Medicine. 27, 1, t. 125-130Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Position statement. Part two: Maintaining immune health
Walsh, N. P., Gleeson, M., Pyne, D. B., Nieman, D. C., Dhabhar, F. S., Shephard, R. J., Oliver, S. J., Bermon, S. & Kajeniene, A., 2011, Yn: Exercise Immunology Review. 17, t. 64-103 40 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Wedi ei Dderbyn / Yn y wasg
Post-exercise hypotension after exercising in hypoxia with and without tart cherry supplementation
Horiuchi, M. & Oliver, S., 26 Hyd 2024, (Wedi ei Dderbyn / Yn y wasg) Yn: High Altitude Medicine and Biology.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Prolonged (9 h) poikilocapnic hypoxia (12% O2) augments cutaneous thermal hyperaemia in healthy humans
Lawley, J. S., Oliver, S. J., Mullins, P. G., Macdonald, J. H. & Moore, J. P., 1 Meh 2014, Yn: Experimental Physiology. 99, t. 909-920Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Re: Luteinizing hormone-releasing hormone agonist effects on skeletal muscle: How hormonal therapy in prostate cancer affects muscular strength
Marcora, S., Oliver, S. J., Callow, N., Lemmey, A. & Stuart, N., 1 Tach 2005, Yn: Journal of Urology. 174, 5, t. 2068-2069Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Response to the Letter to the Editor by Aaron Spital, “Is This Elderly Patient Dehydrated? Diagnostic Accuracy of Hydration Assessment Using Physical Signs, Urine, and Saliva Markers”
Fortes, M., Owen, J., Oliver, S. & Walsh, N. P., 1 Awst 2015, Yn: Journal of the American Medical Directors Association. 16, 8, t. 708Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Reversal of neurovascular coupling in the default mode network: Evidence from hypoxia
Rossetti, G., d'Avossa, G., Rogan, M., Macdonald, J., Oliver, S. & Mullins, P., Ebr 2021, Yn: Journal of Cerebral Blood Flow and Metabolism. 41, 4, t. 805–818 14 t.Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid
- Cyhoeddwyd
Saliva indices track hypohydration during 48 h of fluid restriction or combined fluid and energy restriction.
Oliver, S. J., Laing, S., Wilson, S., Bilzon, J. L. & Walsh, N., 1 Hyd 2008, Yn: Archives of Oral Biology. 53, 10, t. 975-980Allbwn ymchwil: Cyfraniad at gyfnodolyn › Erthygl › adolygiad gan gymheiriaid