An electrically charged point particle with a mass of 1.85 x 10-6 kg is launched horizontally into a uniform electric field with a magnitude of 925 N/C. The particle's initial velocity is 6.82 m/s, directed eastward, and the external electric field is also directed eastward. A short time after being launched, the particle is 9.18 x 10-3 m below and 0.142 m east of its initial position. Determine the net charge carried by the particle, including the algebraic sign ( or -).