A new free recoverable and reusable mono-alkaloid-type ligand and its use in preparation of ethyl （2R,3S）-2,3-dihydroxy-3-phenylpropionate

A new free recoverable and reusable mono-alkaloid-type ligand has been synthesized by a simple method.With highly polar groups,the ligand can be recycled and reused eight times to prepare ethyl(2R,3S)-2,3-dihydroxy-3-phenylpropionate with high yield and ee via asymmetric dihydroxylation(AD) reaction.     

Multiphoton path entanglement by nonlocal bunching

Multiphoton path entanglement is created without applying postselection, by manipulating the state of stimulated parametric down-conversion. A specific measurement on one of the two output spatial modes leads to the nonlocal bunching of the photons of the other mode, forming the desired multiphoton path entangled state. We present experimental results for the case of a heralded two-photon path entangled state and show how to extend this scheme to higher photon numbers.     

Phase-restricted heterogeneous correlation

We introduce a new phase-restricted algorithm for producing a heterogeneous correlation filter that permits new in-class members to be added without changing the phase of the filter. This heterogeneous correlation filter uses amplitude modulation both to enhance in-class cross correlations and to suppress selected out-of-class correlations. This new algorithm should substantially improve the performance of existing class-associative correlators and improve their operation.     

Oligomers from biphenyl,biphenyl-d10, or p-terphenyl with aluminium chloride-cupric chloride: Mechanism,ESR, and conductivity

Biphenyl and biphenyl-d₁₀ were coupled by aluminum chloride-cupric chloride. For the two systems, the yields of p-quaterphenyl, p-sexiphenyl, and sublimation residue were compared. The results, which have mechanistic significance, are similar to those reported earlier for benzene versus benzene-d₆; that is, a decrease in DP for the deuterated substrate. p-Sexiphenyl, obtained from biphenyl or p-terphenyl and aluminum chloride-cupric chloride, displayed a concentration of 3 × 10¹⁷ spins/g in ESR. There was little or no change in spin density after sublimation or crystallization. Even after drastic purification by a variety of techniques the radical character persisted. Biphenyl was polymerized by aluminum chloride-cupric chloride at temperatures in the 50–155°C range. Processable polymers with m- and p-phenylene linkages were produced. When doped with AsF₅, the highest conductivity obtained was 7.3 × 10^?2 Ω^?1 cm^?1.     

Properties of poly(p-phenylene)s and the perdeuterated analog

ESR data for poly(p-phenylene) (PPP) prepared from benzene and catalyst-oxidant systems were compared with data for PPP obtained by a variety of other methods. The results were similar, except for the Yamamoto preparation, and comparable to the spin densities for heterocyclic polymers of thiophene, pyrrole, and selenophene. Deuterated PPP from C₆D₆ showed significant differences in properties, in comparison to ordinary PPP, in relation to molecular weight, color, solubility, and spins/g in electron spin resonance (ESR). The implications are discussed with regard to the mechanism of benzene polymerization by AlCl₃-CuCl₂.     

Chameleon fields: awaiting surprises for tests of gravity in space

We present a novel scenario where a scalar field acquires a mass which depends on the local matter density: the field is massive on Earth, where the density is high, but is essentially free in the solar system, where the density is low. All existing tests of gravity are satisfied. We predict that near-future satellite experiments could measure an effective Newton's constant in space different from that on Earth, as well as violations of the equivalence principle stronger than currently allowed by laboratory experiments.     

The Integration of Genomics into Public Health Research, Policy and Practice in the United States

Objectives: To examine the opportunities for and responsibilities of the public health community in bridging the gap between gene discovery and the application of genetic information to improve health and prevent disease. Methods: We developed genetics-related definitions for the core functions and essential services of public health. We combined these definitions with a visual model to create one possible 'blueprint' for integrating genomics into public health activities. Results: The proposed blueprint and accompanying examples illustrate the important role for genomics throughout public health research, policy and practice. Further refinement and implementation of this blueprint represents an ambitious public health leadership agenda. Conclusions: Opportunities for immediate action include strategic planning for the integration of genomics across programs, developing genomics competencies among health professionals, enhancing surveillance and epidemiologic capacity to aid evidence-based policy making, building partnerships and seeking input from stakeholders and incorporating information about genomics into health communications. Copyright 2001 S. Karger AG, Basel     

Weak disorder: anomalous transport and diffusion are normal yet again

We carry out a detailed study of the motion of particles driven by a constant external force over a landscape consisting of a periodic potential corrugated by a small amount of spatial disorder. We observe anomalous behavior in the form of subdiffusion and superdiffusion and even subtransport over very long time scales. Recent studies of transport over slightly random landscapes have focused only on parameters leading to normal behavior, and while enhanced diffusion has been identified when the external force approaches the critical value associated with the transition from locked to running solutions, the regime of anomalous behavior had not been recognized. We provide a qualitative explanation for the origin of these anomalies, and make connections with a continuous time random walk approach.