32 research outputs found
A high fibered power of a family of varieties of general type dominates a variety of general type
We prove the following theorem:
Fibered Power Theorem: Let X\rar B be a smooth family of positive
dimensional varieties of general type, with irreducible. Then there exists
an integer , a positive dimensional variety of general type , and a
dominant rational map X^n_B \das W_n.Comment: Latex2e (in latex 2.09 compatibility mode). To get a fun-free version
change the `FUN' variable to `n' on the second line (option dedicated to my
friend Yuri Tschinkel). Postscript file with color illustration available on
http://math.bu.edu/INDIVIDUAL/abrmovic/fibered.p
Sur la p-dimension des corps
Let A be an excellent integral henselian local noetherian ring, k its residue
field of characteristic p>0 and K its fraction field. Using an algebraization
technique introduced by the first named author, and the one-dimension case
already proved by Kazuya KATO, we prove the following formula: cd_p(K) = dim(A)
+ p-rank(k), if k is separably closed and K of characteristic zero. A similar
statement is valid without those assumptions on k and K
Aza Cope Rearrangement of Propargyl Enammonium Cations Catalyzed By a Self-Assembled “Nanozyme”
Biodegradation of polyfluorinated biphenyl in bacteria
Fluorinated aromatic compounds are significant environmental pollutants, and microorganisms play important roles in their biodegradation. The effect of fluorine substitution on the transformation of fluorobiphenyl in two bacteria was investigated. Pseudomonas pseudoalcaligenes KF707 and Burkholderia xenovorans LB400 used 2,3,4,5,6-pentafluorobiphenyl and 4,4′-difluorobiphenyl as sole sources of carbon and energy. The catabolism of the fluorinated compounds was examined by gas chromatography–mass spectrometry and fluorine-19 nuclear magnetic resonance spectroscopy (19F NMR), and revealed that the bacteria employed the upper pathway of biphenyl catabolism to degrade these xenobiotics. The novel fluorometabolites 3-pentafluorophenyl-cyclohexa-3,5-diene-1,2-diol and 3-pentafluorophenyl-benzene-1,2-diol were detected in the supernatants of biphenyl-grown resting cells incubated with 2,3,4,5,6-pentafluorobiphenyl, most likely as a consequence of the actions of BphA and BphB. 4-Fluorobenzoate was detected in cultures incubated with 4,4′-difluorobiphenyl and 19F NMR analysis of the supernatant from P. pseudoalcaligenes KF707 revealed the presence of additional water-soluble fluorometabolites.Author has checked copyrightAM