min_temp = 1
    max_temp = 1e5

    # Create temperature array based on number of workers (excluding master)
    temps = np.logspace(np.log10(min_temp), np.log10(max_temp), num_chains-1)

    rate_step_sizes = np.logspace(np.log10(5e-4), np.log10(5e-2),
                                  num_chains-1)
    scaling_step_sizes = np.logspace(np.log10(1e-4), np.log10(1e-2),
                                     num_chains-1)

    # Initialize the MCMC arguments
    b = args['builder']
    opts = MCMCOpts()
    opts.model = b.model
    opts.tspan = args['time']
    opts.estimate_params = b.estimate_params
    opts.initial_values = b.random_initial_values()
    opts.nsteps = args['nsteps']

    #opts.norm_step_size = np.array([0.01] + \
    #                    ([0.05] * (len(opts.estimate_params)-1)))
    # FIXME not correct ordering
    #opts.norm_step_size = np.array([scaling_step_sizes[rank-1]] + \
    #                    ([rate_step_sizes[rank-1]] *
    #                     (len(opts.estimate_params)-1)))
    #print "Step size: %g" % (opts.norm_step_size[1])
    opts.norm_step_size = 0.05

    opts.sigma_step = 0 # Don't adjust step size
    #opts.sigma_max = 50
    # Frequency for proposing swaps
    swap_period = 5
    # Temperature range
    min_temp = 1
    max_temp = 1e5

    # Create temperature array based on number of workers (excluding master)
    temps = np.logspace(np.log10(min_temp), np.log10(max_temp), num_chains-1)

    rate_step_sizes = np.logspace(np.log10(5e-4), np.log10(5e-2), num_chains-1)
    scaling_step_sizes = np.logspace(np.log10(1e-4), np.log10(1e-2), num_chains-1)

    # Initialize the MCMC arguments
    opts = MCMCOpts()
    opts.model = model
    opts.tspan = nbd.time_other
    opts.estimate_params = builder.estimate_params
    opts.initial_values = builder.random_initial_values()
    opts.nsteps = nsteps

    #opts.norm_step_size = np.array([0.01] + \
    #                    ([0.05] * (len(opts.estimate_params)-1)))
    opts.norm_step_size = np.array([scaling_step_sizes[rank-1]] + \
                        ([rate_step_sizes[rank-1]] * (len(opts.estimate_params)-1)))
    print "Step size: %g" % (opts.norm_step_size[1])

    opts.sigma_step = 0 # Don't adjust step size
    opts.sigma_max = 50
    opts.sigma_min = 0.01
    opts.accept_rate_target = 0.23
    opts.accept_window = 100