Simple and efficient production of (Z)-4-hydroxytamoxifen, a potent estrogen receptor modulator

A McMurry coupling reaction and selective crystallization were used to develop a simple and efficient two-step synthesis of (Z)-4-hydroxytamoxifen (2a). This compound is an active metabolite of tamoxifen, a selective estrogen receptor (ER) modulator widely used to treat breast cancer. The synthesis employed 1,1-bis(4-hydroxyphenyl)-2-phenylbut-1-ene (1) as a useful building block.     

DFT prediction and experimental observation of substrate-induced catalyst decomposition in ruthenium-catalyzed olefin metathesis

Ruthenacyclobutane decomposition, involving competitive beta-hydride transfer to Ru and reductive olefin elimination during ruthenium-catalyzed olefin metathesis, is predicted by density functional theory calculations and experimentally confirmed by propene and butene formation during degenerate Ru-methylidene-catalyzed metathesis of ethylene. The results provide new focus on the nature of ruthenium metathesis catalyst decomposition under catalytic conditions.     

The Euler Characteristic Is the Unique Locally Determined Numerical Invariant of Finite Simplicial Complexes which Assigns the Same Number to Every Cone

We show that a proof given by Levitt in [L] suffices to prove the stronger theorem stated in the title. Received April 2, 1999, and in revised form October 6, 1999.     

Transform-Limited Pulses Are Not Optimal for Resonant Multiphoton Transitions

Maximizing nonlinear light-matter interactions is a primary motive for compressing laser pulses to achieve ultrashort transform limited pulses. Here we show how, by appropriately shaping the pulses, resonant multiphoton transitions can be enhanced significantly beyond the level achieved by maximizing the pulse's peak intensity. We demonstrate the counterintuitive nature of this effect with an experiment in a resonant two-photon absorption, in which, by selectively removing certain spectral bands, the peak intensity of the pulse is reduced by a factor of 40, yet the absorption rate is doubled. Furthermore, by suitably designing the spectral phase of the pulse, we increase the absorption rate by a factor of 7.     

Anisotropic scaling of magnetohydrodynamic turbulence

We present a quantitative estimate of the anisotropic power and scaling of magnetic field fluctuations in inertial range magnetohydrodynamic turbulence, using a novel wavelet technique applied to spacecraft measurements in the solar wind. We show for the first time that, when the local magnetic field direction is parallel to the flow, the spacecraft-frame spectrum has a spectral index near 2. This can be interpreted as the signature of a population of fluctuations in field-parallel wave numbers with a k(-2)_(||) spectrum but is also consistent with the presence of a "critical balance" style turbulent cascade. We also find, in common with previous studies, that most of the power is contained in wave vectors at large angles to the local magnetic field and that this component of the turbulence has a spectral index of 5/3.     

Discrete morse theory and the cohomology ring

In [5], we presented a discrete Morse Theory that can be applied to general cell complexes. In particular, we defined the notion of a discrete Morse function, along with its associated set of critical cells. We also constructed a discrete Morse cocomplex, built from the critical cells and the gradient paths between them, which has the same cohomology as the underlying cell complex. In this paper we show how various cohomological operations are induced by maps between Morse cocomplexes. For example, given three discrete Morse functions, we construct a map from the tensor product of the first two Morse cocomplexes to the third Morse cocomplex which induces the cup product on cohomology. All maps are constructed by counting certain configurations of gradient paths. This work is closely related to the corresponding formulas in the smooth category as presented by Betz and Cohen [2] and Fukaya [11], [12].