119,149 research outputs found
A dual catalytic strategy for carbon-phosphorus cross-coupling via gold and photoredox catalysis.
A new method for the P-arylation of aryldiazonium salts with H-phosphonates via dual gold and photoredox catalysis is described. The reaction proceeds smoothly at room temperature in the absence of base and/or additives, and offers an efficient approach to arylphosphonates. The reaction is proposed to proceed through a photoredox-promoted generation of an electrophilic arylgold(III) intermediate that undergoes coupling with the H-phosphonate nucleophile
Reply To "Comment on 'Quantum String Seal Is Insecure' "
In Phys. Rev. A. 76, 056301 (2007), He claimed that the proof in my earlier
paper [Phys. Rev. A 75, 012327 (2007)] is insufficient to conclude the
insecurity of all quantum string seals because my measurement strategy cannot
obtain non-trivial information on the sealed string and escape detection at the
same time. Here, I clarify that our disagreement comes from our adoption of two
different criteria on the minimum amount of information a quantum string seal
can reveal to members of the public. I also point out that He did not follow my
measurement strategy correctly.Comment: 2 page
Comment on "Constraint Quantization of Open String in Background B field and Noncommutative D-brane"
In the paper "Constraint Quantization of Open String in Background field
and Noncommutative D-brane", it is claimed that the boundary conditions lead to
an infinite set of secondary constraints and Dirac brackets result in a
non-commutative Poisson structure for D-brain. Here we show that contrary to
the arguments in that paper, the set of secondary constraints on the boundary
is finite and the non-commutativity algebra can not be obtained by evaluating
the Dirac brackets.Comment: minor corrections, to appear in Phys.Lett.
Centers and Cocenters of -Hecke algebras
In this paper, we give explicit descriptions of the centers and cocenters of
-Hecke algebras associated to finite Coxeter groups.Comment: 13 pages, a mistake in 4.2 is correcte
Estimating species abundance from occurrence
The number of individuals, or the abundance, of a species
in an area is a fundamental ecological parameter and a
critical consideration when making management and conservation decisions (Andrewartha and Birch 1954; Krebs
1978; Gaston 1994; Caughley and Gunn 1996). However,
unless the scale is very fine or localized (e.g., in a measurable habitat or a forest stand), abundance is not readily determined. At coarse or regional scales for many species, information on commonness and rarity is, at best, limited to a map of their presence or absence from recording units in a specified time frame. Various species data at large scales are increasingly documented in this presence/absence forma
Occupancy, spatial variance, and the abundance of species
A notable and consistent ecological observation known for
a long time is that spatial variance in the abundance of a
species increases with its mean abundance and that this relationship typically conforms well to a simple
power law (Taylor 1961). Indeed, such models can be
used at a spectrum of spatial scales to describe spatial
variance in the abundance of a single species at different
times or in different regions and of different species across the same set of areas (Taylor et al. 1978; Taylor and Woiwod 1982)
A concentrator for static magnetic field
We propose a compact passive device as a super-concentrator to create an
extremely high uniform static magnetic field over 50T in a large
two-dimensional free space from a weak background magnetic field. Such an
amazing thing becomes possible for the first time, thanks to space-folded
transformation and metamaterials for static magnetic fields. Finite element
method (FEM) is utilized to verify the performance of the proposed device
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