MODELING THE EFFECTS OF PREDATOR EXCLOSURES ON A WESTERN SNOWY PLOVER POPULATION

Abstract In Humboldt County, California, nest exclosures were used between 2001 and 2006 to reduce the predation of eggs aiding in the recovery of a threatened population segment of western snowy plovers (Charadrius nivosus). Due to a sudden increase in adult mortality in 2006, field biologists abandoned the use of nest exclosures. This paper describes a discrete‐time stochastic model designed to compare two different management strategies (with and without exclosures) to predict the change in the plover population. The model uses beta distributions to model demographic parameters, and whenever possible, these distributions were fit to survey data of these populations. The model shows nest exclosures to be effective in increasing chick fledging rates. However, the model also shows that an increase in adult mortality potentially caused by the nest exclosures would counteract this increase in fledging rates. The model predicts that there will be a net negative effect on the population if these exclosures reduce adult survival to 90% of its unexclosed rate. The model also demonstrates that the population is dependent on immigration.     

All-derivable points in continuous nest algebras

Let be an operator algebra on a Hilbert space. We say that an element is an all-derivable point of for the strong operator topology if every strong operator topology continuous derivable linear mapping φ at G (i.e. φ(ST)=φ(S)T+Sφ(T) for any with ST=G) is a derivation. Let be a continuous nest on a complex and separable Hilbert space H. We show in this paper that every orthogonal projection operator P(M) () is an all-derivable point of for the strong operator topology.     

Elementary maps on nest algebras

Let A₁, A₂ be algebras and let M:A₁→A₂, M^∗:A₂→A₁ be maps. An elementary map of A₁×A₂ is an ordered pair (M,M^∗) such that

     

套代数上保秩一幂零性的可加映射

${\cal N}$和${\cal M}$分别是实或复Banach空间$X$ ($\dim X >5$)和$Y$中的两个套且Alg${\cal N}$和Alg${\cal M}$分别是与套${\cal N}$和${\cal M}$相关的套代数.符号Alg加映射;秩一幂零算子;套代数Additive map,Rank one nilpotent operator,Nest algebra国家自然科学基金;清华大学校科研和教改项目;教育部高等学校博士点教育基金;国家自然科学基金;山西省自然科学基金2005-02-082007年4月25日${\cal N}$和${\cal M}$分别是实或复Banach空间$X$ ($\dim X >5$)和$Y$中的两个套且Alg${\cal N}$和Alg${\cal M}$分别是与套${\cal N}$和${\cal M}$相关的套代数.符号Alg加映射;秩一幂零算子;套代数Additive map,Rank one nilpotent operator,Nest algebra国家自然科学基金;清华大学校科研和教改项目;教育部高等学校博士点教育基金;国家自然科学基金;山西省自然科学基金2005-02-082007年4月25日令N和M分别是实或复Banach空间X(dim X>5)和Y中的两个套且AlgN和AlgM分别是与套N和M相关的套代数．符号AlgFN表示AlgN中所有有限秩算子全体．设Φ:AlgFN→AlgFM是可加映射,且值域包含AlgFM中的所有秩一幂零元．如果Φ-双边保秩一幂零性,作者证明了存在一个域自同构τ及τ-线性算子A和C使得要么对所有的秩一幂零元x(?)f∈AlgFN,Φ(x(?)f)=Ax(?)Cf,要么对所有的秩一幂零元x(?)f∈AlgFN,Φ(x(?)f)=Af(?)Cx．特别地,当X和Y是Hilbert空间且Φ是连续映射时,作者得到这类可加映射Φ的完全刻画．     

套代数上自同构的刻画

本文给出套代数上保零积或者保多项式零化线性映射的刻画,从而得到其上自同构的一些新特征和原子套代数上保零积可加映射的完全分类.     

Nest代数的Jacobson根的μ-核值保持映射

设算子代数Ａ　Ｂ（Ｈ），μ（Ａ）表示Ａ中的部分等距算子全体，若ｐ是Ａ到Ｂ（Ｈ）的线性映射，且对任意的ＵＥｕ（Ａ），有叫Ｕ）（ｋｅｃＵ）Ｇｒ“ｈＣｒ，则称　是Ａ上的μ－核值保持映射。本文将证明：Ｎｅｓｔ代数的Ｊａｃｏｂｓｏｎ根上的范数拓扑连续的μ－核值保持映射是广义内导子。     

Lie Triple Derivable Mappings on Rings

Let ? be a ring containing a nontrivial idempotent. In this article, under a mild condition on ?, we prove that if δ is a Lie triple derivable mapping from ? into ?, then there exists a Z _{A, B} (depending on A and B) in its centre 𝒵(?) such that δ(A + B) = δ(A) + δ(B) + Z _{A, B} . In particular, let ? be a prime ring of characteristic not 2 containing a nontrivial idempotent. It is shown that, under some mild conditions on ?, if δ is a Lie triple derivable mapping from ? into ?, then δ = D + τ, where D is an additive derivation from ? into its central closure T and τ is a mapping from ? into its extended centroid 𝒞 such that τ(A + B) = τ(A) + τ(B) + Z _{A, B} and τ([[A, B], C]) = 0 for all A, B, C ∈ ?.     

Linear Maps Preserving Idempotence on Nest Algebras

In this paper, we discuss the rank-l-preserving linear maps on nest algebras of Hilbertspace operators. We obtain several characterizations of such linear maps and apply them to show that a weakly continuous linear hijection on an atomic nest algebra is idempotent preserving if and only if it is a Jordan homomorphism, and in turn, if and only if it is an automorphism or an anti-automorphism.     

套代数理想的距离公式

设Ｎ是Ｈｉｌｂｅｒｔ空间Ｈ上的一个完备套,是Ｎ上的标准谱测度．本文给出了Ｈ上任一有界线性算子Ｔ到套代数Ａｌｇ　Ｎ的Ｌａｒｓｏｎ理想ＲＮ的距离公式为ＡｌｇＮ的半根理想,则ｄ（Ｔ,ＲＮ）＝ｓｕｐ｛ｉＮ（Ｔ）：Ｎ｝．     

套代数上的Jordan导子

本文主要研究套代数上的Ｊｏｒｄａｎ导子．证明了套代数上的任一Ｊｏｒｄａｎ导子都是内导子；作为应用最后讨论了套代数上的Ｊｏｒｄａｎ自同构．