def overlaps(particle, cell):
    """Check presence of overlaps between particles."""
    x = []
    for i, pi in enumerate(particle):
        for j, pj in enumerate(particle):
            if j <= i:
                continue
            d = sum(pi.distance(pj, cell) ** 2) ** 0.5
            if d < pi.radius + pj.radius:
                x.append((i, j))
    return len(x) > 0, x
