disease, although some suggest further research might still be useful. In a 2009 report about "Rural Wind Farms", a Standing Committee of the Parliament of New South Wales, Australia, recommended a minimum setback of two kilometres between wind turbines and neighboring houses (which can be waived by the affected neighbor) as a precautionary approach. A 2014 paper suggests that the 'Wind Turbine Syndrome' is mainly caused by the nocebo effect and other psychological mechanisms. Australian science magazine Cosmos states that although the symptoms are real for those who suffer from the condition, doctors need to first eliminate known causes (such as pre-existing cancers or thyroid disease) before reaching definitive conclusions with the caveat that new technologies often bring new, previously unknown health risks. Effect on power grid Utility-scale wind farms must have access to transmission lines to transport energy. The wind farm developer may be obliged to install extra equipment or control systems in the wind farm to meet the technical standards set by the operator of a transmission line. The intermittent nature of wind power can pose complications for maintaining a stable power grid when wind farms provide a large percentage of electricity in any one region. Ground radar interference Wind farms can interfere with ground radar systems used for military, weather and air traffic control. The large, rapidly moving blades of the turbines can return signals to the radar that can be mistaken as an aircraft or weather pattern. Actual aircraft and weather patterns around wind farms can be accurately detected, as there is no fundamental physical constraint preventing that. But aging radar infrastructure is significantly challenged with the task. The US military is using wind turbines on some bases, including Barstow near the radar test facility. Effects The level of interference is a function of the signal processors used within the radar, the speed of the aircraft and the relative orientation of wind turbines/aircraft with respect to the radar. An aircraft flying above the wind farm's turning blades could become impossible to detect because the blade tips can be moving at nearly aircraft velocity. Studies are currently being performed to determine the level of this interference and will be used in future site planning. Issues include masking (shadowing), clutter (noise), and signal alteration. Radar issues have stalled as much as 10,000 MW of projects in USA. Some very long range radars are not affected by wind farms.