Archive for the ‘科學’ Category

wolfram alpha

五月 20, 2009

研發 Mathematica 軟件的 Wolfram 最近推出了一個全新的 search engine : Wolfram Alpha.

起 初不怎看好,因為我對 mathematica 的不滿與日俱增,實在不明白為何每個 release 都變得比之前難用,加些無無謂謂的 fancy feacture,user interface 越來越糟糕。現在我寫 program 是為 get things done,早就不再和 mathematica 折騰了。

不過 wolfram alpha 的確幾好玩,不能說可以整死 google,不過肯定能殺出條血路。

true mathematica fashion..!:

moz-screenshot-2

流感數字

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估唔到連終極問題都難佢唔到….:

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廣告

豬流感

五月 3, 2009

Flu Cases Increase, but There Is Some Optimism – NYTimes.com

“Very few confirmed are over 50,” Dr. Schuchat said. “They tend to be younger. Whether it will pan out in the weeks ahead we don’t know, but it is a pattern that looks different from seasonal influenza.”

最近常聽到一個論調說豬流感是傳媒炒作,其實和一般的流感沒有兩樣。這樣說是因為在數字上,每年死於普通流感的人數比這次豬流感多了。

但這個論調忽略了受感染者的年齡分布。一般流感死者大多數是抵抗力低的嬰兒和老年人,而老人死亡或多或少可以說是比較「自然」的死亡--年老力衰後,不少人是病死的。

至於這個新病毒,受感染者不分年齡,全人類都沒有抵抗這病毒的抗體。數學模型告訢我們,一旦受感染人數到了一個數目,病毒就能迅速擴散到整個社群。這時候,即使豬流感的殺傷力只是和普通的流感一樣(如幾個 % 死亡率),也將會是一個相當大的數目。

所以,不要把殺傷力和感染力混為一談。

隱形肢體

四月 15, 2009

The Mind-Body Problem: Scientific American

In Annals of Neurology, the researchers, led by Asaid Khateb, report the case a 64 year-old librarian who began to experience a supernumerary phantom limb four days after being hospitalized with a stroke. The phantom, she said, started from the elbow of her left arm (which had been paralyzed by the stroke) and felt “just like a real hand," but was “weightless." “transparent" and “thinner" than her actual arms. The patient also told the doctors that the phantom was not experienced permanently, but only when she intentionally “triggered" it. Furthermore, it was anatomically correct and functional—she said that it had flexible, independently moveable joints at the elbow, wrist and fingers, and claimed that she could not only see it, but also feel it and purposefully move it.

The doctors placed her into a brain scanner, and asked her to scratch her cheek with her phantom limb. Remarkably, the scan confirmed the patient’s subjective reports. When she willed the phantom limb into action, the doctors observed an increase in the activity of the right motor cortex. When she said that the phantom was approaching her face, they observed an increase in visual cortical activity. And when she told them that the limb had made contact, they observed increased activity in the region of somatosensory cortex corresponding to the cheek. The patient’s brain had generated a virtual simulation of a fully functional arm, which had been incorporated into the body image and which ran alongside the neural representations of her real arms. In her mind, this virtual arm was just as real as her actual arms.

interesting

重覆

二月 17, 2009

從前有個前輩告訢我,不要怕做自己份外的事情。他說,干的時侯或許不覺得有什麼用,後來自然會發現好處。他比較幸運:一件份外的事情,令他能從事一項研究,從而使他找到一份很好的工作。

我也有著很多這樣的經歷。有時是興之所致,想玩玩試試;有時是純是危機感,想多學一些東西。

我覺得收獲最大的,是在讀博士時,我的論文是理論和電腦計算為主,但我在最後兩年做了不少實驗。很多做理論的人都不喜歡做實驗。他們不喜歡與實驗儀器和化學品打交道,有些是動手能力不足,有些是只愛動腦不愛動手(做實驗比做理論的體力和時間要求多很多),也有些理論家覺得自己比實驗工作者懂得多,不屑與之為伍。

我從理論起家,後來學做實驗,當時覺得理論最終都是為解釋和預測實驗結果,如果自己不做,沒有接觸過,很不實在。而且實驗技巧對將來找工作有幫助。

到現在,我從實驗上學到,最受用的本領是不斷地重覆做一件事的能耐。重復實驗是很枯燥無味的,但有趣地不少實驗科學家都很喜歡做實驗,而且是日以繼夜不停地做。我以前只做理論時不明白,但做過實驗後就明白了。重複練習一種技巧,手工完美,感覺比做理論實在得多了。

evolutionary psychology

十二月 27, 2008

Evolution of the Mind: 4 Fallacies of Psychology: Scientific American

有趣地看到這篇文章,和我上文的看法很相近,是對 evolutionary psychology 整個學派的評擊。我看是言之有理。

不過 Scientific American 應該邀請該學派另寫一文回應,好讓讀者知道雙方的理據。

這文受到不少反擊是意料中事。這學派教出來的學者一定不會同意這些觀點 (我看不到學術界有多少獨立思考的人)。更重要的是,被 Sciam 這相有份量的雜誌登出對這學派的質疑,以後這些研究組要拿 funding 就難得多了。沒有錢就沒有學生、沒有研究的基礎,好快玩完。

說到底,我是覺得這些「進化解釋」很吹水,完全是 speculation,寫下書寫下 blog 就可以。這些所謂知識和 hard science有本質上的區別。

進化解釋

十二月 22, 2008

The Scientist : No peace without biology [19th December 2008 02:18 PM GMT]

Investigating human nature | Of music, murder and shopping | The Economist

如果要我舉出一種似是而非的論據,莫過於所謂的 evolutionary explanation,即用「進化論」來解釋一種行為為何存在。

幾乎每一種和人有關的現像,從「為何人有上進心」,到「為何有戰爭」,都是進化的必然結果。

我不反對這些觀點,我關心的是如何證明?如果理論無從證實,只是聽起來 make sense,好聽叫 hand-waving argument,唔好聽叫吹水。

外星生物

十一月 27, 2008

有人發現,好遠好遠的星球有二氧化碳:

http://www.nature.com/news/2008/081121/full/news.2008.1248.html

他們認為,二氧化碳是生命出現的先決條件,是四大 biomarker 之一。

是,不過只是基於觀察一個樣本(地球)的結論。

我偏向認為,組成生命體的物質不重要,結構更重要。如果這些結構能夠以其他物質組成,生命就能實現了。

現在只知道一個樣本,在什麼環境下才能存在生物還是說不準吧。