at the front of

An allee effect at the front of a plant invasion: Spartina in a Pacific estuary.
Electron acceleration by a short relativistic laser pulse at the front of solid targets.
Current Losses at the Front of Silicon Heterojunction Solar Cells
Life at the front of an expanding population
Submarine silicic caldera at the front of the Izu-Bonin Arc, Japan : Voluminous seafloor eruptions of rhyolite pumice
Concerning the maximum energy of ions accelerated at the front of a relativistic electron cloud expanding into vacuum
Increases in the low-energy cosmic ray intensity at the front of propagating interplanetary shock waves
Tectonic erosion at the front of the Japan Trench convergent margin
Tectonics and volcanism of Sierra Chichinautzin: extension at the front of the Central Trans-Mexican Volcanic belt
Foredeep geometries at the front of the Apennines in the Ionian Sea (central Mediterranean)