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

Transforming magnets

Based on the form-invariant of Maxwell's equations under coordinate transformations, we extend the theory of transformation optics to transformation magneto-statics, which can design magnets through coordinate transformations. Some novel DC magnetic field illusions created by magnets (e.g. shirking magnets, cancelling magnets and overlapping magnets) are designed and verified by numerical simulations. Our research will open a new door to designing magnets and controlling DC magnetic fields

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

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

Cocommutative Calabi-Yau Hopf algebras and deformations

The Calabi-Yau property of cocommutative Hopf algebras is discussed by using the homological integral, a recently introduced tool for studying infinite dimensional AS-Gorenstein Hopf algebras. It is shown that the skew-group algebra of a universal enveloping algebra of a finite dimensional Lie algebra \g with a finite subgroup $G$ of automorphisms of \g is Calabi-Yau if and only if the universal enveloping algebra itself is Calabi-Yau and $G$ is a subgroup of the special linear group SL(\g). The Noetherian cocommutative Calabi-Yau Hopf algebras of dimension not larger than 3 are described. The Calabi-Yau property of Sridharan enveloping algebras of finite dimensional Lie algebras is also discussed. We obtain some equivalent conditions for a Sridharan enveloping algebra to be Calabi-Yau, and then partly answer a question proposed by Berger. We list all the nonisomorphic 3-dimensional Calabi-Yau Sridharan enveloping algebras

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 $B$ 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.