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1 天前 · The resistivity can be expressed using the SI unit ohm metre (Ω⋅m) — i.e. ohms multiplied by square metres (for the cross-sectional area) then divided by metres (for the length).Both resistance and resistivity describe how difficult it is to make electrical current flow through a material, but unlike resistance, resistivity is an intrinsic property and does not depend on geometric ...
1 天前 · Richard Phillips Feynman (/ ˈ f aɪ n m ə n /; May 11, 1918 – February 15, 1988) was an American theoretical physicist, known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics, the physics of the superfluidity of supercooled liquid helium, as well as his work in particle physics for which he proposed the parton model.
2 天前 · Joseph Eugene Stiglitz ( / ˈstɪɡlɪts /; born February 9, 1943) is an American New Keynesian economist, [2] a public policy analyst, and a full professor at Columbia University. He is a recipient of the Nobel Memorial Prize in Economic Sciences (2001) [3] and the John Bates Clark Medal (1979). [4] He is a former senior vice president and ...
2 天前 · Principal component analysis (PCA) is a linear dimensionality reduction technique with applications in exploratory data analysis, visualization and data preprocessing. The data is linearly transformed onto a new coordinate system such that the directions (principal components) capturing the largest variation in the data can be easily identified.
3 天前 · Pearson correlation coefficient. Several sets of ( x , y) points, with the correlation coefficient of x and y for each set. The correlation reflects the strength and direction of a linear relationship (top row), but not the slope of that relationship (middle), nor many aspects of nonlinear relationships (bottom).
3 天前 · Dymaxion map of the world with the 30 largest countries and territories by area This is a list of the world's countries and their dependencies by land, water, and total area, ranked by total area.The entries in this list include, but are not limited to, those in the ISO 3166-1 standard, which includes sovereign states and dependent territories.
3 天前 · Leo Tolstoy at age 20, c. 1848. Tolstoy was born at Yasnaya Polyana, a family estate 12 kilometres (7.5 mi) southwest of Tula, and 200 kilometres (120 mi) south of Moscow. He was the fourth of five children of Count Nikolai Ilyich Tolstoy (1794–1837), a veteran of the Patriotic War of 1812, and Princess Mariya Tolstaya (née Volkonskaya; 1790 ...
