bp_core_new_user_activity( array $user )

function bp_core_new_user_activity( $user ) {
	if ( empty( $user ) ) {
		return false;
	}

	if ( is_array( $user ) ) {
		$user_id = $user['user_id'];
	} else {
		$user_id = $user;
	}

	if ( empty( $user_id ) ) {
		return false;
	}

	bp_activity_add( array(
		'user_id'   => $user_id,
		'component' => buddypress()->members->id,
		'type'      => 'new_member'
	) );
}