Skip to menu Skip to content Skip to footer

Find an expert

1 - 18 of 18 results

Professor Ammar Abdul Aziz

Affiliate of Centre for Nutrition and Food Sciences
Centre for Nutrition and Food Sciences
Queensland Alliance for Agriculture and Food Innovation
Professor & School Director, Higher Degree Research
School of Agriculture and Food Sustainability
Faculty of Science
Availability:
Not available for supervision
Ammar Abdul Aziz
Ammar Abdul Aziz

Associate Professor Paul Dennis

Affiliate of Centre for Marine Science
Centre for Marine Science
Faculty of Science
Affiliate Associate Professor of School of Agriculture and Food Sustainability
School of Agriculture and Food Sustainability
Faculty of Science
Associate Professor in Env Science
School of the Environment
Faculty of Science
Availability:
Available for supervision

Paul Dennis leads an exciting research group that applies cutting-edge technologies to understand the roles of microorganisms and their responses to environmental change.

He is also a passionate educator and public speaker who advocates for the importance of biological diversity and evidence-based environmental awareness. He has talked about his research on ABC Radio and a range of other media outlets.

His teaching covers aspects of ecology, microbiology, plant and soil science, and climatology. He considers these topics to be of fundamental importance for the development of more sustainable societies and takes pride in helping others to obtain the knowledge and skills they need to build a better future.

Paul's research has taken him to Antarctica, the Amazon Rainforest, high mountains and oceans. The approaches used in his lab draw on a wide range of expertise in molecular biology, ecology, statistics, computer science, advanced imaging and soil science. He applies these skills to a wide-range of topics and systems including plant-microbe interactions, Antarctic marine and terrestrial ecology, biogeography, pollution and human health.

Paul Dennis
Paul Dennis

Professor Mansour Edraki

Professorial Research Fellow
Centre for Water in the Minerals Industry
Faculty of Engineering, Architecture and Information Technology
Availability:
Available for supervision
Media expert

Dr Mansour Edraki is a geo-environmental scientist specialising in the field of inorganic geochemistry. He joined UQ in 2000 following completion of his PhD at University of New England. Prior to that, and before immigrating to Australia, he was a lecturer in earth sciences. Since joining UQ, Dr Edraki has focused on developing innovative techniques for understanding and predicting geochemical processes which underpin sustainable management of mine waste and mine water, particularly acid and metalliferous drainage. Mansour’s research has direct applications for the resources and energy industries and the impact of his work is evident in a continuous flow of industry-funded projects in the last decade. Dr Edraki has initiated research collaborations in many international locations including Indonesia (South Kalimantan and Freeport), Iran (Mehdiabad Zinc) Papua New Guinea (Ok Tedi), Philippines (USEP and Mindanao Development Authority), Korea (MIRECO and KIGAM), Peru (INGEMET), and Chile (Fundación Chile, Universidad de Concepción). Dr Edraki represents SMI-UQ at International Network for Acid Prevention (INAP), which is a global alliance for managing the issue of acid and metalliferous drainage. He leads SMI's Environmental Geochemistry Group.

Mansour Edraki
Mansour Edraki

Dr Valerie Hagger

Affiliate of Centre for Biodiversity and Conservation Science
Centre for Biodiversity and Conservation Science
Faculty of Science
Research Fellow
School of the Environment
Faculty of Science
Availability:
Available for supervision

Valerie’s research focusses on coastal ecosystem conservation and restoration. She holds an AXA-UNESCO research fellowship on mangrove community forestry for resilient coastal livelihoods, endorsed as an action of the UN Ocean Decade. She co-leads a National Environmental Science Program (NESP) project on carbon abatement and biodiversity enhancements from controlling feral ungulates in wetlands in Australia and is developing a framework to measure verified biodiversity benefits in coastal wetland restoration projects in partnership with CSIRO. She recently led a NESP project on coastal wetland restoration opportunities in Australia for blue carbon and co-benefits for biodiversity, fisheries, water quality, and coastal protection and an Australian Research Council linkage project to identify social and ecological conditions that enable effective mangrove conservation over global and regional scales with partners at The Nature Conservancy and Healthy Land and Water. She has published research on the drivers of global mangrove losses and gains and coastal wetland restoration opportunities. She has co-authored international guidelines on mangrove restoration with Conservation International and incorporation of coastal wetlands into national greenhouse gas inventories with the Australian Government International Blue Carbon Partnerships. Valerie is an experienced ecologist and is a board member of the Society of Ecological Restoration Australasia and a representative of Australia’s Restoration Decade Alliance.

Valerie Hagger
Valerie Hagger

Dr Anthony Halog

Lecturer
School of the Environment
Faculty of Science
Availability:
Available for supervision
Media expert

Dr. Anthony Halog: A Pioneer in Sustainable Systems and Circular Economy

Dr. Anthony Halog is a leading authority in sustainable systems engineering and circular economy, with over 22 years of post-PhD experience in academia and research. His work focuses on integrating life cycle assessment (LCA), systems thinking, and industrial ecology to advance global sustainability efforts. Dr. Halog has successfully led numerous research projects in industrial ecology and sustainable supply chain management, contributing significantly to the United Nations Sustainable Development Goals (UNSDGs) and Planetary Boundaries frameworks.

His prolific career includes over 125 publications that have been widely cited and referenced in policy documents by international bodies such as the United Nations and the European Union. With a strong commitment to mentoring, Dr. Halog has guided numerous PhD candidates and postdoctoral researchers, fostering the next generation of sustainability experts. Since completing his PhD, he has examined numerous theses from various universities in Australia, North America, Africa, and Asia. His experience also extends to reviewing several grant proposals for prestigious funding bodies, including the National Science Foundation in the USA and European funding schemes.

Dr. Anthony Halog has received numerous fellowships and awards throughout his career. Notably, he was awarded fellowships from prestigious institutions such as the OECD, DAAD, and the Japan Society for the Promotion of Science (JSPS). He has held visiting fellowships across the globe, including in the UK, Germany, Japan, and Saudi Arabia, focusing on areas like Circular Economy, Green Hydrogen Policy, and Life Cycle Assessment. Dr. Halog's accolades also include early career fellowships from NSERC (Canada) and JSPS, along with several international research grants and academic scholarships, reflecting his global recognition in sustainability science and engineering.

Key areas of expertise include circular economy, bioeconomy, LCA, sustainable supply chain management, and the application of operations research and optimization in engineering sustainable systems. Dr. Halog’s interdisciplinary approach and international collaborations have positioned him as a thought leader in transitioning to a low-carbon, circular economy.

Anthony Halog
Anthony Halog

Professor Longbin Huang

Program Leader/Prof Res Fellow
Centre for Mined Land Rehabilitation
Faculty of Engineering, Architecture and Information Technology
Availability:
Available for supervision
Media expert

Science and technology of ecological engineering of ferrous and base metal mine tailings (e.g., magnetite tailings, bauxite residues (or red mud), Cu/Pb-Zn tailings) into functional technosols and hardpan-based soil systems for sustainable tailings rehabilitation: geo-microbial ecology, mineral bioweathering, geo-rhizosphere biology, technosol-plant relations in mined environments. Championing nature-based solutions to global mine wastes challenges.

Longbin Huang is a full professor and a Program leader in The University of Queensland, leading a research program of "Ecological Engineering in Mining" to develop naure-based methdology and technology, for assisting the world's mining industry to meet the global tailings challenge. Driven by the passion to translate leading knowledge into industry solutions, Longbin has pioneered transformative concepts and approach to tackle rehabilitation of mine wastes (e.g., tailings, acidic and metalliferous waste rocks). Recent success includes the "ecological engineering of Fe-ore tailings and bauxite residue" into soil, for overcoming the topsoil deficit challenge facing the mining industry. Scaled up field trials have been going on to deliver the much-needed technology into field operations. Long-term and multi-site based field trials have demonstrated for the first time, the field-feasibility to accelerate nature-based soil formaiton processes for developing tailings into adaptive and sustainable soil (or technosol) capable of sustaining plant community growth and development (https://www.youtube.com/watch?v=6VzfiWL-8UI&t=4s).

The program consists of a group of researchers with leading knowledge and research skills on: soil/geo-microbial ecology, environmental mineralogy, bioweathering of minerals, native plant rhizosphere (micro)biology, soil-plant relations, and environmental materials (such as biochar and environmental geopolymers). It aims to deliver transformative knowledge and practices (i.e., technologies/methdologies) in the rehabilitation of mine wastes (e.g., tailings, mineral residues, spoils, waste rocks) and mined landscapes for non-polluting and ecologically and financially sustainable outcomes.

In partnership with leading mining companies, Longbin and his team have been focusing on developing game-changing knowledge and technologies of tailings valorisation for achieving non-polluting and ecologically sustainable rehabilitation of, for example, coal mine spoils and tailings, Fe-ore tailings, bauxite residues (or red mud), and Cu/Pb-Zn tailings. Leading the global progress in bauxite rehabilitation, Longbin and his team are currently taking on field-scale research projects on bauxite residue rehabilitation technologies at alumina refineries in Queensland (QAL- and Yarwun refineries) and Northern Territory (Gove refinery).

Longbin's industry-partnered research was recognised in 2019 UQ’s Partners in Research Excellence Award (Resilient Environments) (Rio Tinto and QAL).

Membership of Board, Committee and Society

Professional associations and societies

2010 – Present Australian Soil Science Society.

2016 – Present Soil Science Society of America

2015 – Present American Society of Mining and Reclamation (ASMR)

Editorial boards/services

2018 - present: Member of Editorial Board, BIOCHAR

2013 – present: coordinating editor, Environmental Geochemistry and Health

Awards & Patent

2019 UQ’s Partners in Research Excellence Award (Resilient Environments) (Rio Tinto and QAL)

2017 SMI-Industry Engagement Award, University of Queensland

2015 SMI-Inaugural Bright Research Ideas Forum Award, University of Queensland

2014 SMI-RHD Supervision Award, University of Queensland

2015 Foliar fertilizer US 20150266786. In. (Google Patents). Huang L, Nguyen AV, Rudolph V, Xu G (equal contribution)

Longbin Huang
Longbin Huang

Dr Julius Kotir

Adjunct Senior Fellow
School of Agriculture and Food Sustainability
Faculty of Science
Lecturer
School of Agriculture and Food Sustainability
Faculty of Science
Availability:
Available for supervision
Media expert

Dr Julius Kotir is a Senior Scientist with the Queensland Government Department of Agriculture and Fisheries and also an Adjunct Senior Fellow in the School of Agriculture and Food Sustainability. His academic and research interest is focused on understanding and managing the complex and long-term sustainability of coupled socio-economic-environmental systems. A particular interest is how to use this understanding to design decision support tools in the form of models to evaluate the impact of different options under an uncertain global future. His work takes an interdisciplinary approach, combining participatory co-design and field-based methods with systems thinking tools and system dynamics modelling to develop qualitative and quantitative simulation models that can support decision making. Julius has is currently using these tools and methods to address a wide range of complex agri-environmental problems including international and rural development issues, food security, economics of farming systems, agrifood and digital twin supply chains, climate-smart agriculture, water resources management, farmer adoption of new practices, and agribusiness policy design and analysis.

Julius Kotir
Julius Kotir

Associate Professor Nina Lansbury

Affiliate of Centre of Architecture, Theory, Culture, and History
Centre of Architecture, Theory, Criticism and History
Faculty of Engineering, Architecture and Information Technology
Associate Professor
School of Public Health
Faculty of Health, Medicine and Behavioural Sciences
Availability:
Available for supervision
Media expert

Associate Professor Nina Lansbury (also published as Nina Hall) is an environmental public health research and teaching academic at The University of Queensland’s School of Public Health. Her current research at UQ examines environmental health aspects that support the health and wellbeing of remote Indigenous community residents on both mainland Australia and in the Torres Strait in terms of housing, water and sanitation, and women's health. She also investigates the impacts of climate change on human health, and this involved a role as Lead Author on the Intergovernmental Panel on Climate Change (IPCC AR6 WG II). Within the research sector, she was previously a senior research scientist at CSIRO, manager of the Sustainable Water program at The University of Queensland, and senior research consultant at the Institute for Sustainable Futures, UTS. Within the non-government sector, she was previously the director of the Climate Action Network Australia and research coordinator at the Mineral Policy Institute.

Nina Lansbury
Nina Lansbury

Dr Marguerite Renouf

Honorary Associate Professor
School of Chemical Engineering
Faculty of Engineering, Architecture and Information Technology
Availability:
Not available for supervision

Marguerite Renouf BSc(Hons)/BA, PhD (Env Man) UQ is a Research Fellow at the School of Chemical Engineering's Water-Energy-Carbon Research Group (www.chemeng.uq.edu.au/water-energy-carbon).

She has worked in environmental research at UQ for 20 years, with a particular interest in the environmental evaluation of production systems and urban systems using environmental life cycle assessment (LCA), urban metabolism evaluation and eco-efficiency analysis. She is interested how we can produce and consume with less drain on the environment.

Since completing a PhD in 2011, she has driven a stream of research that evaluates the environmental performance of agri-based product supply chains and products (bio-fuels, bio-materials, food, beverages) using LCA. She has collaborated with industries and researchers in Australia and overseas to develop LCA tools for industry to support the identification of more environmentally-friendly production practices and processes.

Prior to this, her research was concerned with eco-efficiency in manufacturing industries (food processing, metal industries, retail and tourism sectors) and was a long-term contributor to UQ’s Working Group for Cleaner Production (now operating as the Eco-Efficienc Group), and its Director for three years (2009-2012).

Currently, Marguerite is a lead researcher with the CRC for Water Sensitive Cities, develop methods and metrics for quantifiying the water water-sensitive performance of Australian cities, using urban metabolism approaches. In this work she collaborates cloesely with urban planners, water manager and architects.

Marguerite Renouf
Marguerite Renouf

Dr April Reside

Affiliate of Centre for Biodiversity and Conservation Science
Centre for Biodiversity and Conservation Science
Faculty of Science
Senior Lecturer in AgroEcology
School of Agriculture and Food Sustainability
Faculty of Science
Senior Lecturer in AgroEcology
School of the Environment
Faculty of Science
Availability:
Available for supervision
Media expert

April Reside is a lecturer in the School of the Environment and School of Agriculture and Food Sustainability, affiliated with the Centre for Biodiversity and Conservation Science.

Dr Reside's research encompasses ecology, conservation, and policy; investigating refuges and refugia; and recovery actions and their costs for Australia’s threatened species. April also works on conservation of woodland bird communities, the impact of climate change on biodiversity, and strategies for climate change adaptation. This work has involved applying conservation planning frameworks to identify spatial priorities for climate change adaptation for biodiversity and carbon sequestration.

April has a particular fascination of flying vertebrates, and has worked on bats on three continents and nine countries. She worked as a field ecologist for non-government organisations before her PhD on understanding potential impacts of climate change on Australian tropical savanna birds. She adapted species distribution modelling techniques to account for temporal and spatial variability in the distributions of highly vagile bird species. These dynamic species distribution models take into account species’ responses to fluctuations in weather and short-term climatic conditions rather than long-term climate averages. In her first postdoctoral position, Dr Reside modelled the distribution of c.1700 vertebrates across Australia at a fine resolution, and located the future location of suitable climate for all these species for each decade until 2085. From this, she identified hotspots across Australia where species were moving to in order to track their suitable climate, informing the IUCN SSC Guidelines for Assessing Species’ Vulnerability to Climate Change by the IUCN Species Survival Commission.

April has been involved in conservation of the Black-throated Finch for over 12 years, and is Chair of the Black-throated Finch Recovery Team. She has served on Birdlife Australia's Research and Conservation Committee and Threatened Species Committee; and the Science Committee for the Invasive Species Council.

April Reside
April Reside

Associate Professor Chris Roelfsema

Affiliate of Centre for Marine Science
Centre for Marine Science
Faculty of Science
Affiliate of Centre for Biodiversity and Conservation Science
Centre for Biodiversity and Conservation Science
Faculty of Science
Associate Professor
School of the Environment
Faculty of Science
Availability:
Available for supervision
Media expert

Research interest: Monitoring ecosystem health of coral reefs and seagrass habitats, integrating field and remote sensing image datasets, and the developing applied cost-effective mapping and monitoring approaches. Developed approaches have been adopted as standard practice globally, making a difference in conservation of these valuable habitats. The long term monitoring studies at Heron and Moreton Bay formed the basis for the development of mapping and monitoring over time and space at local to global scale. See here major research impact

Major projects:

  • Long term monitoring of benthic composition at Heron Reef (2002-ongoing).
  • Long term monitoring of seagrass composition and abundance in Moreton bay Marine Park (2000-ongoing).
  • Smart Sat CRC Hyperspectral Remote Sensing of Seagrass and Coral Reefs 2023-2027.
  • Developement of Underwater Field Spectrometry and Benthic Photo Collection and Analysis
  • 3D GBR Habitat Mapping Project 2015 - ongoing:
  • Global habitat mapping project 2019-2023 Allen Coral Atlas .

Current position: Associate Professior in Marine Remote Sensing leading the Marine Ecosystem Monitoring Lab. . Academic Director Heron Island Research Station and affiliated researchers with Centre for Marine Science and Centre for Biodiversity and Conservation Science

Capacity Building and Citizen Science: Capacity: under/post graduate courses; Msc/PhD supervision, workshops/courses; Remote Sensing Educational Toolkit, and online courses (e.g. TNC).Strong supporter of citizen science based projects, as trainer, organiser and advisor for Reef Check Australia, CoralWatch, Great Reef Census and UniDive.

Chris Roelfsema
Chris Roelfsema

Miss Katerina Savinova

Research Fellow
W.H. Bryan Mining and Geology Research Centre
Faculty of Engineering, Architecture and Information Technology
Availability:
Available for supervision

Katerina is a geologist with a specialization in hyperspectral data analysis as applied to mineral identification and interpretation, with big data integration. She has 15 years of hands-on experience working on both ground-breaking research and commercial activities for greenfield, brownfield and mining projects of various scales around the world. While with Corescan, she pioneered innovation in hyperspectral data acquisition, interpretation, and presentation. She developed and interpreted the results of complex algorithms associated with various mineral hyperspectral signatures. As part of her work, she contributed to geochemical and geotechnical research as applied to hydrothermal mineral alteration patterns associated with several world-class deposits, deposit delineation initiatives, new exploration projects, as well as geoenvironmental studies of acid-rock drainage and mining waste characterization. In her earlier roles, as an exploration geologist, she worked on uranium deposits in Canada, the USA, and Australia, with a focus on the system controls and definition of hydrothermal alteration mineral zonation and spatial patterns. Currently, Katerina is collaborating on several long-term projects with different challenges related to geological and mining industries at the W.H. Bryan Mining and Geology Research Centre, SMI including critical minerals research, mineral and textural characterization as applied to mine waste and tailings, as well as development of educational material and short-course delivery. Specific areas of research and interest include:

  • Hydrothermal alteration mineralogy and its characterization using high-resolution hyperspectral data in combination with other micro-analytical techniques
  • Remote sensing techniques and data interpretation
  • Detailed investigation of a variety of geological environments and mineral deposit settings including epithermal, unconformity-associated uranium, orogenic gold, porphyry, skarn, as well as IOCG
  • Minerals and mineral groups, their chemical composition and variations, recognizing hydrothermal alteration patterns and identifying vectors to mineralization
  • Establishment of new mineralogical and hyperspectral reflectance tools for drill core characterization for various mining applications
Katerina Savinova
Katerina Savinova

Dr Tina Skinner

Postdoctoral Research Fellow
School of the Environment
Faculty of Science
Availability:
Not available for supervision
Media expert
Tina Skinner
Tina Skinner

Associate Professor Laura Sonter

Affiliate of Centre for Biodiversity and Conservation Science
Centre for Biodiversity and Conservation Science
Faculty of Science
Adjunct Associate Professor
School of the Environment
Faculty of Science
Availability:
Available for supervision
Media expert

Reconciling biodiversity conservation with development pressures is one of the world’s greatest sustainability challenges. This is particularly true given the myriad ways that human wellbeing directly depends on well-functioning ecosystems. My research seeks to understand where, when and how to manage and conserve landscapes, so as to beneift both nature and people. I use land use change models, coupled with remote sensing and GIS datasets, to predict how future development projects (e.g. mines, hydropower dams, transportation infrastructure) will impact biodiversity and ecosystem services. This information allows us to compare the costs and benefits of alternative management interventions and, ultimately, provides the knowledge needed to make more informed decisions. My research benefits from collaborating across disciplines (ecology, economics, engineering) and working alongside government and non-government organizations. I am currently conducting projects in Australia, Brazil and the USA.

Laura Sonter
Laura Sonter

Dr Ryan Turner

Senior Research Fellow
School of the Environment
Faculty of Science
Availability:
Available for supervision
Media expert

Associate Professor Ryan Turner is the Director of the Reef Catchments Science Partnership at the University of Queensland (a partnership with the Department of the Environment, Tourism, Science and Innovation). Ryan was previously the Department's Principal Scientist for Water Quality and Investigations and held an Adjunct Associate Professor role at Queensland University of Technology in the Managing for Resilient Landscapes, Institute for Future Environments. For 14 years, Ryan managed multimillion-dollar water quality monitoring programs assessing the impacts of sediments, nutrients, and pesticides in numerous catchments along the Queensland coast discharging to the Great Barrier Reef and Moreton Bay. Ryan has been on several steering committees and technical advisory panels, such as the Great Barrier Reef Foundations Technical Advisory Panel. He has published extensively (>80 papers and reports) and led several Queensland Government – Academic collaborative research projects. Ryan previously supervised analytical chemistry and microbiology laboratories in the private and public sectors. Ryan has developed numerous methodologies and standard operating procedures for analytical and monitoring techniques (water quality, sediments and soils). Ryan’s passion for the future of water security is what keeps him striving forward.

Ryan Turner
Ryan Turner

Dr Franzisca Weder

Honorary Senior Research Fellow
School of Communication and Arts
Faculty of Humanities, Arts and Social Sciences
Availability:
Available for supervision
Media expert

Assoc. Prof. Dr. habil Franzisca Weder, Senior Lecturer at the University of Queensland, Brisbane (Australia), is researching, writing and teaching in the areas of Organizational Communication and Public Relations with a specific focus on Sustainability Communication and Corporate Social Responsibility.

She worked as Guest Professor at University of Alabama (USA), University of Eichstätt-Ingolstadt (GER), University of Waikato (NZ), RMIT (Melbourne, AUS) and University of Ilmenau (GER).

Franzisca Weder is Chair of the International Environmental Communication Association (IECA) -> check this out (and become a member :-): https://www.theieca.org

Curious about her work? check…

  • her eco-culture jamming
  • her sustainability related conversations with artists and campaigners
  • one of her papers on Sustainability and Storytelling
  • one of her books
    • on Sustainability Communication: THE SUSTAINABILITY COMMUNICATION READER
    • on integrated CSR Communication: INTEGRATED CSR COMMUNICATION
    • or (in case you speak German..) on Organizational Communication and PR
  • or other recent papers:
    • on how (much) Covid made us more sustainable
    • on sustainability as cognitive friction https://www.frontiersin.org/articles/10.3389/fcomm.2020.00008/full
    • or on antagonistic framing and CSR Communication https://www.emerald.com/insight/content/doi/10.1108/CCIJ-01-2018-0014/full/html
    • or (in case you speak German), her ideas on cultures of sustainability
Franzisca Weder
Franzisca Weder

Dr Shuanglei Wu

Honorary Research Fellow
School of the Environment
Faculty of Science
Availability:
Available for supervision
Shuanglei Wu

Dr Jennifer Yarnold

Senior Research Fellow
Centre for Policy Futures
Faculty of Humanities, Arts and Social Sciences
Availability:
Available for supervision

Jennifer's research focuses on the intersection between policy, social and technology solutions for system transitions including decarbonisation and circular economy.

In addition to traditional research, Jennifer leads two programs within the Centre for Policy Futures – the Policy Impact Program (PIP) and the Policy Engagement Program (PEP). The PIP is a collaboration between UQ and the Winston Churchill Memorial Trust which curates a selection of the best ideas from Churchill Fellows that have the potential to guide best-practice policy reform in Australia. Its flagship piece is the Policy Futures: A Reform Agenda publication. Through the PEP, experts on a policy-priority topics are engaged in roundtable discussions to guide the development of the Centre’s Policy Futures Think Piece series - designed to unpack complex topics for policy makers.

Jennifer is currently collaborating on projects including organics recycling innovations and carbon market opportunities in north Queensland; policy protections and social safeguards for critical minerals development; and a comparative analysis of state-based circular economy policies.

Jennifer is an environmental scientist by training with expertise in environmental microbiology, plant science and phycology, photosynthesis, mathematical modelling and systems modelling. Interests include sustainable food systems, carbon sequestration, environmental markets, renewable energy, bioeconomy, circular business models and UN Sustainable Development Goals.

Jennifer Yarnold
Jennifer Yarnold