我必须找到数据集中最陡坡度的起点和终点。数据集显示了实验过程中的温度变化。冷却从大约420帧开始，到大约500帧结束。有人能帮我计算这些分数吗？

y = [308.09262874940794, 308.1216944088393, 308.2620809214068, 308.2185299674233, 308.0441705852154, 308.06355616177564, 307.9374947672655, 308.15075314506964, 308.0684020743851, 307.9859953521339, 308.0974735069697, 308.1265380121872, 308.09262874940794, 308.0780933219296, 307.9859953521339, 308.0247819257457, 308.0005417638036, 308.1555955950364, 308.09262874940794, 308.0780933219296, 308.17496347364175, 308.2185299674233, 308.20400953030344, 308.2378878644666, 308.2524042737181, 308.22336972940053, 308.3056163523782, 308.3829743977657, 308.34913627709466, 308.08778379939605, 308.3636394757246, 308.3636394757246, 308.3636394757246, 308.4844326170746, 308.4361296746482, 308.5375438416535, 308.460283529643, 308.5761557193945, 308.64852019740135, 308.69673945106905, 308.53271650065454, 308.6919183792268, 308.63405072092854, 308.55202472271446, 308.585806786816, 308.6533429765644, 308.6822756666845, 308.7690327906589, 308.64852019740135, 308.735301202496, 308.8364681549037, 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在我的第一次尝试中，我使用了最大累积：

i = np.argmax(np.maximum.accumulate(y) - y)
j = np.argmax(y[:i])
plt.plot(y)
plt.plot([i, j], [y[i], y[j]], 'o', color='Red', markersize=10)

它发现降幅最大，但不是最陡的