[lemma=amount] [lemma=of] [lemma=time] [□] □
[lemma=amount] [lemma=of] [lemma=time] [□=□] □
[lemma=amount] [lemma=of] [lemma=time] [!□] □
There are ecological as well as economic advantages to increasing the amount of time the land is used for production . These personal exposure measurements reflect the average magnitude of the magnetic field produced by the various EMF sources and the amount of time the worker spent in the fields . For example , the gains from virtual endoscopy almost certainly need to take into account the amount of time the surgeon or radiographer spends conducting the inspection . Such measurements do not necessarily reflect a worker 's personal EMF exposure because they are not always taken at a distance from the source that approximates the worker 's location , they generally do n't account for the amount of time the worker is actually there , and exposure may be different at other times during the day . This is however the only way to collect high signal to noise calibrations , hence special automatic tools have been developed to optimize the number of frames acquired in the short amount of time the sky brightness is within the right range .