brachistochrone.The growth of maize, sugarcane and sorghum 高粱....For most of the time that photosynthetic cells that turn sunlight into food have existed,

 The growth of maize, sugarcane and sorghum has been greatly boosted by modifying the plants to take advantage of higher carbon dioxide levels now found in the air.

This was done by simply increasing the activity of two genes, says Coralie Salesse-Smith at the University of Illinois. The finding should lead to the creation of new varieties whose yields go up as CO2 levels continue to rise.

For most of the time that photosynthetic cells that turn sunlight into food have existed, atmospheric levels of CO2 have been much higher (and the planet has been much hotter). As CO2 levels fell particularly low from about 35 million years ago, it exacerbated a fundamental flaw in photosynthesis that involves probably the most abundant protein on the planet, called rubisco.

透過改造植物以利用空氣中較高的二氧化碳含量，玉米、甘蔗和高粱的生長得到了極大的促進。

伊利諾大學的 Coralie Salesse-Smith 說，這是透過簡單地增加兩個基因的活性來實現的。這項發現應該會導致新品種的誕生，其產量會隨著二氧化碳水平的持續上升而上升。

在將陽光轉化為食物的光合細胞存在的大部分時間裡，大氣中二氧化碳的含量要高得多（而且地球也更熱）。由於二氧化碳水平從大約 3500 萬年前開始下降得特別低，它加劇了光合作用的一個基本缺陷，該缺陷涉及可能是地球上最豐富的蛋白質，稱為 rubisco。

梁國淦

4分鐘  · 

普物，學期初有安排

為同學準備數學知識的幾堂課。

力學、統物、和熱物則是在進行中

抓出重要的課題面對之。

這很正常。

但因為不是數學課，也要衡量

學生背景的不齊、

和課程時間的限制。

需要盡量一刀中的，不執著於數學，不昧於物理。

幾年下來，

發現 Felix Klein 在

《Elementary Mathematics from a Higher Standpoint》

這套書裡採用的一些觀點，

和我最終選擇的切入點有越來越多的重合。

深入思索，

才感受到他當時寫這套書的構思。

對的事有無限多種對的觀點；

能了解越多，當然可能使人的眼界和想像空間擴大，

但時間精力不夠時，

也可以參考名家指引的 brachistochrone。

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A brachistochrone is a curve that connects two points at different heights, and is the fastest path for an object to travel between them. The word comes from the Greek words brachistos which means "shortest" and chronos which means "time".