bluuebunny/crossref_metadata_2025 huggingface dataset:
Resultants and the algebraicity of the join pairing on Chow varieties
Authors: Plümer Judith
Published: July 2002

The Chow/Van der Waerden approach to algebraic cycles via resultants is used to give a purely algebraic proof for the algebraicity of the complex suspension. The algebraicity of the join pairing on Chow varieties then follows. The approach implies a more algebraic proof of Lawson’s complex suspension theorem in characteristic 0. The continuity of the action of the linear isometries operad on the group completion of the stable Chow variety is a consequence.
A four-dimensional deformation of a numerical Godeaux surface
Authors: Werner Caryn
Published: July 2002

A numerical Godeaux surface is a surface of general type with invariants

p
g

=
q
=
0

p_g =q =0

and

K
2

=
1

K^2 =1

. In this paper the moduli space of a numerical Godeaux surface with order two torsion is computed to be eight-dimensional; whether or not the moduli space of such a surface is irreducible is still unknown. The surface in this paper is constructed as one member of a four parameter family of double planes. There is a natural involution on the surface, inherited from the double plane construction, which acts on the moduli space. We show that the invariant subspace is four-dimensional and coincides with the family of double planes.
Extensions of modules over Weyl algebras
Authors: Coutinho S.
Published: July 2002

In this paper we calculate some

E
x
t

\mathrm {Ext}

groups of singular modules over the complex Weyl algebra

A

n

A_{n}

. In particular we determine conditions under which

E
x
t

\mathrm {Ext}

is an infinite dimensional vector space when

n
=
2

n =2

or

3
3

.
𝐿²-homology over traced *-algebras
Authors: Paschke William
Published: July 2002

Given a unital complex *-algebra

A
A

, a tracial positive linear functional

τ
\tau

on

A
A

that factors through a *-representation of

A
A

on Hilbert space, and an

A
A

-module

M
M

possessing a resolution by finitely generated projective

A
A

-modules, we construct homology spaces

H
k

(
A
,
τ
,
M
)

H_k(A,\tau ,M)

for

k
=
0
,
1
,
…

k = 0, 1, \ldots

. Each is a Hilbert space equipped with a *-representation of

A
A

, independent (up to unitary equivalence) of the given resolution of

M
M

. A short exact sequence of

A
A

-modules gives rise to a long weakly exact sequence of homology spaces. There is a Künneth formula for tensor products. The von Neumann dimension which is defined for

A
A

-invariant subspaces of

L
2

(
A
,
τ

)
n

L^2(A,\tau )^n

gives well-behaved Betti numbers and an Euler characteristic for

M
M

with respect to

A
A

and

τ
\tau

.
Invariant cocycles, random tilings and the super-𝐾 and strong Markov properties
Authors: Schmidt Klaus
Published: July 2002

We consider

1
1

-cocycles with values in locally compact, second countable abelian groups on discrete, nonsingular, ergodic equivalence relations. If such a cocycle is invariant under certain automorphisms of these relations, we show that the skew product extension defined by the cocycle is ergodic. As an application we obtain an extension of many recent results of the author and K. Petersen to higher-dimensional shifts of finite type, and prove a transitivity result concerning rearrangements of certain random tilings.
A combinatorial correspondence related to Göllnitz’ (big) partition theorem and applications
Authors: Alladi Krishnaswami
Published: July 2002

In recent work, Alladi, Andrews and Gordon discovered a key identity which captures several fundamental theorems in partition theory. In this paper we construct a combinatorial bijection which explains this key identity. This immediately leads to a better understanding of a deep theorem of Göllnitz, as well as Jacobi’s triple product identity and Schur’s partition theorem.
Liouville type theorems for fourth order elliptic equations in a half plane
Authors: Friedman Avner , Velázquez Juan
Published: July 2002

Consider an elliptic equation

ω
Δ
φ
−

Δ
2

φ
=
0

\omega \Delta \varphi -\Delta ^2\varphi =0

in the half plane

{
(
x
,

y
)
,

−
∞
>
x
>
∞
,

y
>
0
}

\{(x,\,y),\,-\infty >x>\infty ,\,y>0\}

with boundary conditions

φ
=

φ
y

=
0

\varphi =\varphi _y=0

if

y
=
0
,

x
>
0

y=0,\,x>0

and

B
j

φ
=
0

B_j\varphi =0

if

y
=
0
,

x
>
0

y=0,\,x>0

where

B
j

B_j

(
j
=
2
,
3
)

(j=2,3)

are second and third order differential operators. It is proved that if

R
e

ω
≥
0
,

ω
≠
0

Re\,\omega \geq 0,\,\omega \neq 0

and, for some

ε
>
0

\varepsilon >0

,

|

φ

|

≤
C

r
α

|\varphi |\leq Cr^\alpha

if

r
=

x
2

+

y
2

→
∞
,

|

φ

|

≤
C

r
β

r=\sqrt {x^2+y^2}\to \infty ,\quad |\varphi |\leq Cr^\beta

if

r
→
0

r\to 0

where

α
=
n
+

1
2

−
ε

,

β
=
n
+

1
2

+
ε

\alpha =n+\frac {1}{2}-\varepsilon \,,\quad \beta =n+\frac {1}{2}+\varepsilon

for some nonnegative integer

n
n

, then

φ
≡
0

\varphi \equiv 0

. Results of this type are also established in case

ω
=
0

\omega =0

under different conditions on

α
\alpha

and

β
\beta

; furthermore, in one case

B
3

φ

B_3\varphi

has a lower order term which depends nonlocally on

φ
\varphi

. Such Liouville type theorems arise in the study of coating flow; in fact, they play a crucial role in the analysis of the linearized version of this problem. The methods developed in this paper are entirely different for the two cases (i)

R
e

ω
≥
0
,

ω
≠
0

Re\,\omega \geq 0,\,\omega \neq 0

and (ii)

ω
=
0

\omega =0

; both methods can be extended to other linear elliptic boundary value problems in a half plane.
A homotopy classification of certain 7-manifolds
Authors: Kruggel Bernd
Published: July 2002

This paper gives a homotopy classification of Wallach spaces and a partial homotopy classification of closely related spaces obtained by free

S
1

S^1

-actions on

S
U
(
3
)

SU(3)

and on

S
3

×

S
5

S^3\times S^5

.
Approximation by harmonic functions
Authors: Poletsky Evgeny
Published: July 2002

For a compact set

X
⊂

R

n

X\subset \mathbb R^n

we construct a restoring covering for the space

h
(
X
)

h(X)

of real-valued functions on

X
X

which can be uniformly approximated by harmonic functions. Functions from

h
(
X
)

h(X)

restricted to an element

Y
Y

of this covering possess some analytic properties. In particular, every nonnegative function

f
∈
h
(
Y
)

f\in h(Y)

, equal to 0 on an open non-void set, is equal to 0 on

Y
Y

. Moreover, when

n
=
2

n=2

, the algebra

H
(
Y
)

H(Y)

of complex-valued functions on

Y
Y

which can be uniformly approximated by holomorphic functions is analytic. These theorems allow us to prove that if a compact set

X
⊂

C

X\subset \mathbb C

has a nontrivial Jensen measure, then

X
X

contains a nontrivial compact set

Y
Y

with analytic algebra

H
(
Y
)

H(Y)

.
Nonsymmetric systems on nonsmooth planar domains
Authors: Verchota G. , Vogel A.
Published: July 2002

We study boundary value problems, in the sense of Dahlberg, for second order constant coefficient strongly elliptic systems. In this class are systems without a variational formulation, viz. the nonsymmetric systems. Various similarities and differences between this subclass and the symmetrizable systems are examined in nonsmooth domains.
Sur la multiplicité de la première valeur propre de l’opérateur de Schrödinger avec champ magnétique sur la sphère
Authors: Besson Gérard , Colbois Bruno , Courtois Gilles
Published: July 2002

L’objet de cet article est d’étudier la multiplicité de la première valeur propre de l’opérateur de Schrödinger avec champ magnétique sur la sphère

S

2

S^{2}

, et, répondant en cela à une question posée par Y. Colin de Verdière, de montrer d’une part que cette multiplicité peut être arbitrairement grande, mais que, d’autre part, elle est toujours bornée en fonction de la courbure de la connexion associée. Abstract. The purpose of this text is to study the first eigenvalue of the Schrödinger operator with magnetic field on the 2-sphere and to show that its multiplicity can be arbitrarily high. We also show that this multiplicity is bounded in terms of the curvature of the corresponding connection. This answers a question asked by Y. Colin de Verdière.
Quantum cohomology of projective bundles over ℙⁿ
Authors: Qin Zhenbo , Ruan Yongbin
Published: July 2002

In this paper we study the quantum cohomology ring of certain projective bundles over the complex projective space

P

n

\mathbb {P}^{n}

. Using excessive intersection theory, we compute the leading coefficients in the relations among the generators of the quantum cohomology ring structure. In particular, Batyrev’s conjectural formula for quantum cohomology of projective bundles associated to direct sum of line bundles over

P

n

\mathbb {P}^{n}

is partially verified. Moreover, relations between the quantum cohomology ring structure and Mori’s theory of extremal rays are observed. The results could shed some light on the quantum cohomology for general projective bundles.
Galois rigidity of pro-𝑙 pure braid groups of algebraic curves
Authors: Nakamura Hiroaki , Takao Naotake
Published: July 2002

In this paper, Grothendieck’s anabelian conjecture on the pro-llfundamental groups of configuration spaces of hyperbolic curves is reduced to the conjecture on those of single hyperbolic curves. This is done by estimating effectively the Galois equivariant automorphism group of the pro-llbraid group on the curve. The process of the proof involves the complete determination of the groups of graded automorphisms of the graded Lie algebras associated to the weight filtration of the braid groups on Riemann surfaces.
On Non-hyperbolic Quasi-convex Spaces
Authors: Ruggiero Rafael
Published: July 2002

We show that if the universal covering of a compact Riemannian manifold with no conjugate points is a quasi-convex metric space then the following assertion holds: Either the universal covering of the manifold is a hyperbolic geodesic space or it contains a quasi-isometric immersion of

Z
×
Z

Z\times Z

.
On the enhancement of diffusion by chaos, escape rates and stochastic instability
Authors: Collet Pierre , Martínez Servet , Schmitt Bernard
Published: July 2002

We consider stochastic perturbations of expanding maps of the interval where the noise can project the trajectory outside the interval. We estimate the escape rate as a function of the amplitude of the noise and compare it with the purely diffusive case. This is done under a technical hypothesis which corresponds to stability of the absolutely continuous invariant measure against small perturbations of the map. We also discuss in detail a case of instability and show how stability can be recovered by considering another invariant measure.
Forcing minimal extensions of Boolean algebras
Authors: Koszmider Piotr
Published: July 2002

We employ a forcing approach to extending Boolean algebras. A link between some forcings and some cardinal functions on Boolean algebras is found and exploited. We find the following applications: 1) We make Fedorchuk’s method more flexible, obtaining, for every cardinal

λ
\lambda

of uncountable cofinality, a consistent example of a Boolean algebra

A

λ

A_{\lambda }

whose every infinite homomorphic image is of cardinality

λ
\lambda

and has a countable dense subalgebra (i.e., its Stone space is a compact S-space whose every infinite closed subspace has weight

λ
\lambda

). In particular this construction shows that it is consistent that the minimal character of a nonprincipal ultrafilter in a homomorphic image of an algebra

A
A

can be strictly less than the minimal size of a homomorphic image of

A
A

, answering a question of J. D. Monk. 2) We prove that for every cardinal of uncountable cofinality it is consistent that

2

ω

=
λ

2^{\omega }=\lambda

and both

A

λ

A_{\lambda }

and

A

ω

1

A_{\omega _{1}}

exist. 3) By combining these algebras we obtain many examples that answer questions of J.D. Monk. 4) We prove the consistency of MA +

¬
\neg

CH + there is a countably tight compact space without a point of countable character, complementing results of A. Dow, V. Malykhin, and I. Juhasz. Although the algebra of clopen sets of the above space has no ultrafilter which is countably generated, it is a subalgebra of an algebra all of whose ultrafilters are countably generated. This proves, answering a question of Arhangel

′

’

skii, that it is consistent that there is a first countable compact space which has a continuous image without a point of countable character. 5) We prove that for any cardinal

λ
\lambda

of uncountable cofinality it is consistent that there is a countably tight Boolean algebra

A
A

with a distinguished ultrafilter

∞
\infty

such that for every

a
∌
∞

a\not \ni \infty

the algebra

A

|

a

A|a

is countable and

∞
\infty

has hereditary character

λ
\lambda

.
Steady-state bifurcation with Euclidean symmetry
Authors: Melbourne Ian
Published: July 2002

We consider systems of partial differential equations equivariant under the Euclidean group

E

(
n
)

\mathbf {E}(n)

and undergoing steady-state bifurcation (with nonzero critical wavenumber) from a fully symmetric equilibrium. A rigorous reduction procedure is presented that leads locally to an optimally small system of equations. In particular, when

n
=
1

n=1

and

n
=
2

n=2

and for reaction-diffusion equations with general

n
n

, reduction leads to a single equation. (Our results are valid generically, with perturbations consisting of relatively bounded partial differential operators.) In analogy with equivariant bifurcation theory for compact groups, we give a classification of the different types of reduced systems in terms of the absolutely irreducible unitary representations of

E

(
n
)

\mathbf {E}(n)

. The representation theory of

E

(
n
)

\mathbf {E}(n)

is driven by the irreducible representations of

O

(
n
−
1
)

\mathbf {O}(n-1)

. For

n
=
1

n=1

, this constitutes a mathematical statement of the ‘universality’ of the Ginzburg-Landau equation on the line. (In recent work, we addressed the validity of this equation using related techniques.) When

n
=
2

n=2

, there are precisely two significantly different types of reduced equation: scalar and pseudoscalar, corresponding to the trivial and nontrivial one-dimensional representations of

O

(
1
)

\mathbf {O}(1)

. There are infinitely many possibilities for each

n
≥
3

n\ge 3

.
Spin 𝐿-functions on 𝐺𝑆𝑝₈ and 𝐺𝑠𝑝₁₀
Authors: Bump Daniel , Ginzburg David
Published: July 2002

The “spin” L-function of an automorphic representation of

G
S

p

2
n

GSp_{2n}

is an Euler product of degree

2

n

2^{n}

associated with the spin representation of the L-group

G
S
p
i
n

(
2
n
+
1
)

\mathrm {GSpin}(2n+1)

. If

n
=
4

n=4

or

5
5

, and the automorphic representation is generic in the sense of having a Whittaker model, the analytic properties of these L-functions are studied by the Rankin-Selberg method.
Weight distributions of geometric Goppa codes
Authors: Duursma Iwan
Published: July 2002

The in general hard problem of computing weight distributions of linear codes is considered for the special class of algebraic-geometric codes, defined by Goppa in the early eighties. Known results restrict to codes from elliptic curves. We obtain results for curves of higher genus by expressing the weight distributions in terms of

L
L

-series. The results include general properties of weight distributions, a method to describe and compute weight distributions, and worked out examples for curves of genus two and three.
Scrambled sets of continuous maps of 1-dimensional polyhedra
Authors: Mai Jiehua
Published: July 2002

Let

K
K

be a 1-dimensional simplicial complex in

R
3

R^3

without isolated vertexes,

X
=

|

K

|

X = |K|

be the polyhedron of

K
K

with the metric

d
K

d_K

induced by

K
K

, and

f
:
X
→
X

f:X\rightarrow X

be a continuous map. In this paper we prove that if

K
K

is finite, then the interior of every scrambled set of

f
f

in

X
X

is empty. We also show that if

K
K

is an infinite complex, then there exist continuous maps from

X
X

to itself having scrambled sets with nonempty interiors, and if

X
=
R

X = R

or

R
+

R_+

, then there exist

C
∞

C^\infty

maps of

X
X

with the whole space

X
X

being a scrambled set.
Closed incompressible surfaces in knot complements
Authors: Finkelstein Elizabeth , Moriah Yoav
Published: July 2002

In this paper we show that given a knot or link

K
K

in a

2
n

2n

-plat projection with

n
≥
3

n\ge 3

and

m
≥
5

m\ge 5

, where

m
m

is the length of the plat, if the twist coefficients

a

i
,
j

a_{i,j}

all satisfy

|

a

i
,
j

|

>
1

|a_{i,j}|>1

then

S
3

−
N
(
K
)

S^3-N(K)

has at least

2
n
−
4

2n-4

nonisotopic essential meridional planar surfaces. In particular if

K
K

is a knot then

S
3

−
N
(
K
)

S^3-N(K)

contains closed incompressible surfaces. In this case the closed surfaces remain incompressible after all surgeries except perhaps along a ray of surgery coefficients in

Z

⊕

Z

\mathbb {Z}\oplus \mathbb {Z}

.
Left-symmetric algebras for 𝔤𝔩(𝔫)
Authors: Baues Oliver
Published: July 2002

We study the classification problem for left-symmetric algebras with commutation Lie algebra

g
l

(
n
)

{\mathfrak {gl}}(n)

in characteristic

0
0

. The problem is equivalent to the classification of étale affine representations of

g
l

(
n
)

{\mathfrak {gl}}(n)

. Algebraic invariant theory is used to characterize those modules for the algebraic group

SL
⁡
(
n
)

\operatorname {SL}(n)

which belong to affine étale representations of

g
l

(
n
)

{\mathfrak {gl}}(n)

. From the classification of these modules we obtain the solution of the classification problem for

g
l

(
n
)

{\mathfrak {gl}}(n)

. As another application of our approach, we exhibit left-symmetric algebra structures on certain reductive Lie algebras with a one-dimensional center and a non-simple semisimple ideal.
Bilipschitz homogeneous Jordan curves
Authors: Ghamsari Manouchehr , Herron David
Published: July 2002

We characterize bilipschitz homogeneous Jordan curves by utilizing quasihomogeneous parameterizations. We verify that rectifiable bilipschitz homogeneous Jordan curves satisfy a chordarc condition. We exhibit numerous examples including a bilipschitz homogeneous quasicircle which has lower Hausdorff density zero. We examine homeomorphisms between Jordan curves.
A quantum octonion algebra
Authors: Benkart Georgia , Pérez-Izquierdo José
Published: July 2002

Using the natural irreducible 8-dimensional representation and the two spin representations of the quantum group

U

q

U_{q}

(D

4

_{4}

) of D

4

_{4}

, we construct a quantum analogue of the split octonions and study its properties. We prove that the quantum octonion algebra satisfies the q-Principle of Local Triality and has a nondegenerate bilinear form which satisfies a q-version of the composition property. By its construction, the quantum octonion algebra is a nonassociative algebra with a Yang-Baxter operator action coming from the R-matrix of

U

q

U_{q}

(D

4

_{4}

). The product in the quantum octonions is a

U

q

U_{q}

(D

4

_{4}

)-module homomorphism. Using that, we prove identities for the quantum octonions, and as a consequence, obtain at

q
=
1

q = 1

new “representation theory” proofs for very well-known identities satisfied by the octonions. In the process of constructing the quantum octonions we introduce an algebra which is a q-analogue of the 8-dimensional para-Hurwitz algebra.
On minimal parabolic functions and time-homogeneous parabolic ℎ-transforms
Authors: Burdzy Krzysztof , Salisbury Thomas
Published: July 2002

Does a minimal harmonic function

h
h

remain minimal when it is viewed as a parabolic function? The question is answered for a class of long thin semi-infinite tubes

D
⊂

R

d

D\subset \mathbb {R}^{d}

of variable width and minimal harmonic functions

h
h

corresponding to the boundary point of

D
D

“at infinity.” Suppose

f
(
u
)

f(u)

is the width of the tube

u
u

units away from its endpoint and

f
f

is a Lipschitz function. The answer to the question is affirmative if and only if

∫

∞

f

3

(
u
)
d
u
=
∞

\int ^{\infty }f^{3}(u)du = \infty

. If the test fails, there exist parabolic

h
h

-transforms of space-time Brownian motion in

D
D

with infinite lifetime which are not time-homogenous.
Spectra of 𝐵𝑃-linear relations, 𝑣_{𝑛}-series, and 𝐵𝑃 cohomology of Eilenberg-Mac Lane spaces
Authors: Tamanoi Hirotaka
Published: July 2002

On Brown-Peterson cohomology groups of a space, we introduce a natural inherent topology, BP topology, which is always complete Hausdorff for any space. We then construct a spectra map which calculates infinite BP-linear sums convergent with respect to the BP topology, and a spectrum which describes infinite sum BP-linear relations in BP cohomology. The mod

p
p

cohomology of this spectrum is a cyclic module over the Steenrod algebra with relations generated by products of exactly two Milnor primitives. We show a close relationship between BP-linear relations in BP cohomology and the action of the Milnor primitives on mod

p
p

cohomology. We prove main relations in the BP cohomology of Eilenberg–Mac Lane spaces. These are infinite sum BP-linear relations convergent with respect to the BP topology. Using BP fundamental classes, we define

v

n

v_{n}

-series which are

v

n

v_{n}

-analogues of the

p
p

-series. Finally, we show that the above main relations come from the

v

n

v_{n}

-series.
On the homotopy of simplicial algebras over an operad
Authors: Fresse Benoit
Published: July 2002

According to a result of H. Cartan, the homotopy of a simplicial commutative algebra is equipped with divided power operations. In this article, we show how to extend this result to other kinds of algebras. For instance, we prove that the homotopy of a simplicial Lie algebra is equipped with the structure of a restricted Lie algebra.
Products and duality in Waldhausen categories
Authors: Weiss Michael , Williams Bruce
Published: July 2002

The natural transformation

Ξ
\Xi

from

L

\mathbf {L}

–theory to the Tate cohomology of

Z

/

2

\mathbb {Z} /2

acting on

K

\mathbf {K}

–theory commutes with external products. Corollary: The Tate cohomology of

Z

/

2

\mathbb {Z} /2

acting on the

K

\mathbf {K}

–theory of any ring with involution is a generalized Eilenberg–Mac Lane spectrum, and it is 4–periodic.
A hereditarily indecomposable tree-like continuum without the fixed point property
Authors: Minc Piotr
Published: July 2002

A hereditarily indecomposable tree-like continuum without the fixed point property is constructed. The example answers a question of Knaster and Bellamy.
Large Sophie Germain primes
Authors: Dubner Harvey
Published: July 2002

If

P
P

is a prime and

2
P
+
1

2P+1

is also prime, then

P
P

is a Sophie Germain prime. In this article several new Sophie Germain primes are reported, which are the largest known at this time. The search method and the expected search times are discussed.
Quadrature formulae using zeros of Bessel functions as nodes
Authors: Ben Ghanem Riadh
Published: July 2002

A gaussian type quadrature formula, where the nodes are the zeros of Bessel functions of the first kind of order

α
\alpha

(

ℜ
(
α
)
>
−
1

\Re (\alpha ) > -1

), was recently proved for entire functions of exponential type. Here we relax the restriction on

α
\alpha

as well as on the function. Some applications are also given.
Lectures on affine Hecke algebras and Macdonald’s conjectures
Authors: Kirillov Alexander
Published: July 2002

This paper gives a review of Cherednik’s results on the representation-theoretic approach to Macdonald polynomials and related special functions. Macdonald polynomials are a remarkable 2-parameter family of polynomials which can be associated to every root system. As special cases, they include the Schur functions, theqq-Jacobi polynomials, and certain spherical functions on real andpp-adic symmetric spaces. They have a number of elegant combinatorial properties, which, however, are extremely difficult to prove. In this paper we show that a natural setup for studying these polynomials is provided by the representation theory of Hecke algebras and show how this can be used to prove some of the combinatorial identities for Macdonald polynomials.
Sum1, a Component of the Fission Yeast eIF3 Translation Initiation Complex, Is Rapidly Relocalized During Environmental Stress and Interacts with Components of the 26S Proteasome
Authors: Dunand-Sauthier Isabelle , Walker Carol , Wilkinson Caroline , Gordon Colin , Crane Richard , Norbury Chris , Humphrey Tim
Published: July 2002

Eukaryotic translation initiation factor 3 (eIF3) is a multisubunit complex that plays a central role in translation initiation. We show that fission yeast Sum1, which is structurally related to known eIF3 subunits in other species, is essential for translation initiation, whereas its overexpression results in reduced global translation. Sum1 is associated with the 40S ribosome and interacts stably with Int6, an eIF3 component, in vivo, suggesting that Sum1 is a component of the eIF3 complex. Sum1 is cytoplasmic under normal growth conditions. Surprisingly, Sum1 is rapidly relocalized to cytoplasmic foci after osmotic and thermal stress. Int6 and p116, another putative eIF3 subunit, behave similarly, suggesting that eIF3 is a dynamic complex. These cytoplasmic foci, which additionally comprise eIF4E and RNA components, may function as translation centers during environmental stress. After heat shock, Sum1 additionally colocalizes stably with the 26S proteasome at the nuclear periphery. The relationship between Sum1 and the 26S proteasome was further investigated, and we find cytoplasmic Sum1 localization to be dependent on the 26S proteasome. Furthermore, Sum1 interacts with the Mts2 and Mts4 components of the 26S proteasome. These data indicate a functional link between components of the structurally related eIF3 translation initiation and 26S proteasome complexes.
Function of the Tetraspanin CD151–α6β1 Integrin Complex during Cellular Morphogenesis
Authors: Zhang Xin A. , Kazarov Alexander R. , Yang Xiuwei , Bontrager Alexa L. , Stipp Christopher S. , Hemler Martin E.
Published: July 2002

Upon plating on basement membrane Matrigel, NIH3T3 cells formed an anastomosing network of cord-like structures, inhibitable by anti-α6β1 integrin antibodies. For NIH3T3 cells transfected with human CD151 protein, the formation of a cord-like network was also inhibitable by anti-CD151 antibodies. Furthermore, CD151 and α6β1 were physically associated within NIH3T3 cells. On removal of the short 8-amino acid C-terminal CD151 tail (by deletion or exchange), exogenous CD151 exerted a dominant negative effect, as it almost completely suppressed α6β1-dependent cell network formation and NIH3T3 cell spreading on laminin-1 (an α6β1 ligand). Importantly, mutant CD151 retained α6β1 association and did not alter α6β1-mediated cell adhesion to Matrigel. In conclusion, the CD151–α6β1 integrin complex acts as a functional unit that markedly influences cellular morphogenesis, with the CD151 tail being of particular importance in determining the “outside-in” functions of α6β1-integrin that follow ligand engagement. Also, antibodies to α6β1 and CD151 inhibited formation of endothelial cell cord-like networks, thus pointing to possible relevance of CD151–α6β1 complexes during angiogenesis.
The Localization of the Integral Membrane Protein Cps1p to the Cell Division Site is Dependent on the Actomyosin Ring and the Septation-Inducing Network inSchizosaccharomyces pombe
Authors: Liu Jianhua , Tang Xie , Wang Hongyan , Oliferenko Snezhana , Balasubramanian Mohan K.
Published: July 2002

Schizosaccharomyces pombe cells divide by medial fission through the use of an actomyosin-based contractile ring. Constriction of the actomyosin ring is accompanied by the centripetal addition of new membranes and cell wall material. In this article, we characterize the mechanism responsible for the localization of Cps1p, a septum-synthesizing 1,3-β-glucan synthase, to the division site during cytokinesis. We show that Cps1p is an integral membrane protein that localizes to the cell division site late in anaphase. Neither F-actin nor microtubules are essential for the initial assembly of Cps1p to the medial division site. F-actin, but not microtubules, is however important for the eventual incorporation of Cps1p into the actomyosin ring. Assembly of Cps1p into the cell division ring is also dependent on the septation-inducing network (SIN) proteins that regulate division septum formation after assembly of the actomyosin ring. Fluorescence-recovery after-photobleaching experiments reveal that Cps1p does not diffuse appreciably within the plasma membrane and is retained at the division site by a mechanism that does not depend on an intact F-actin cytoskeleton. We conclude that the actomyosin ring serves as a spatial cue for Cps1p localization, whereas the maintenance of Cps1p at the division site occurs by a novel F-actin– and microtubule-independent mechanism. Furthermore, we propose that the SIN proteins ensure localization of Cps1p at the appropriate point in the cell cycle.
Representation of functional information in the SWISS-PROT Data
Bank
Authors: L.Junker V. , Apweiler R. , Bairoch A.
Published: July 2002

Summary: Functional information in SWISS-PROT results, primarily, from assessment of articles reporting characterization. Predicted information is labeled with flags describing the evidence level (e.g. potential, probable, by similarity).

Availability: SWISS-PROT can be accessed via http://www.expasy.ch/sprotand http://www.ebi.ac.uk/swissprot/

Contact: junker@ebi.ac.uk
Modeling splice sites with Bayes networks
Authors: Cai Deyou , Delcher Arthur , Kao Ben , Kasif Simon
Published: July 2002

Motivation: The main goal in this paper is to develop accurate probabilistic models for important functional regions in DNA sequences (e.g. splice junctions that signal the beginning and end of transcription in human DNA). These methods can subsequently be utilized to improve the performance of gene-finding systems. The models built here attempt to model long-distance dependencies between non-adjacent bases.

Results: An efficient modeling method is described which models biological data more accurately than a first-order Markov model without increasing the number of parameters. Intuitively, a small number of parameters helps a learning system to avoid overfitting. Several experiments with the model are presented, which show a small improvement in the average accuracy as compared with a simple Markov model. These experiments suggest that single long distance dependencies do not help the recognition problem, thus confirming several previous studies which have used more heuristic modeling techniques.

Availability: This software is available for download and as a web resource at http://www.ai.uic.edu/software

Contact: kasif@eecs.uic.edu
Stock Market Wealth and Consumer Spending
Authors: Starr‐McCluer Martha
Published: July 2002

This article investigates the effects of stock market wealth on consumer spending. Traditional macroeconometric models estimate that a dollar's increase in stock wealth boosts consumption by three to seven cents. With the substantial 1990s rise in stock prices, the nature and magnitude of this “wealth effect” have been much debated. After describing the issues and previous research, I present new evidence from a well‐known consumer survey. The results are broadly consistent with life‐cycle saving and a modest wealth effect: most stockholders reported no appreciable effect of stock prices on their saving or spending, but many mentioned “retirement saving” in explaining their behavior.
A REEXAMINATION OF RESOURCE ALLOCATION RESPONSES TO THE 65‐MPH SPEED LIMIT
Authors: Greenstone Michael
Published: July 2002

In a recent issue of Economic Inquiry (35[3]: 614–20) Lave and Elias (1997) contend that the 1987 increase in speed limits to 65 mph on rural interstate roads caused a reduction in statewide fatality rates. They argue that increased fatality rates on rural interstates were counterbalanced by declines on other roads due to compensatory reallocations of drivers and state police. This article is unable to find any empirical evidence of these reallocations. This removes the empirical basis for their hypothesis and implies that the effect of the 65‐mph speed limit can be inferred from an analysis of rural interstates only. On these roads, fatality rates increased dramatically.
Microalbumin measurement alone or calculation of the albumin/creatinine ratio for the screening of hypertension patients?
Authors: Derhaschnig Ulla , Kittler Harald , Woisetschläger Christian , Bur Andreas , Herkner Harald , Hirschl Michael M.
Published: July 2002

Background. Spot urine sampling seems to be a reliable screening method for the detection of microalbuminuria in hypertensive patients. It remains unclear whether microalbumin measurement alone or calculation of the albumin/creatinine ratio (ACR) are more reliable for the detection of microalbuminuria in non-selected hypertensive patients.

Methods. Following collection of a spot, midstream urine sample, urine was collected for 24 h for the measurement of microalbumin in 264 hypertensive patients. We compared microalbumin concentration in the spot urine with microalbumin measured in the 24-h urine sample and examined the utility of the ACR in evaluating microalbuminuria in hypertensive patients. Pathologic microalbuminuria was assumed when the microalbumin concentration exceeded 30 mg/l in the 24-h urine sample. Diagnostic performance is expressed in terms of specificity, sensitivity, positive (PPV) and negative predictive value (NPV), and area under receiver operating characteristics curve (AUC).

Results. A total of 47 samples (17.8%) showed pathologic microalbuminuria in the 24-h urine sample. The diagnostic performance expressed as AUC was 0.94 (95% CI 0.90–0.98) for microalbumin measurement alone and 0.94 (95% CI 0.89–0.97) for ACR. The PPV and NPV were 44.2 and 97.9% for microalbumin measurement alone. ACR revealed a PPV of 29.3% and a NPV of 96.2% for males and 42.9 and 98% for females, if a cut-off value of 2.5 mg/mmol for males and of 4.0 mg/mmol for females was used.

Conclusions. The ACR did not provide any advantage compared with microalbumin measurement alone, but requires an additional determination of creatinine and the use of gender-specific cut-off values. Therefore, measurement of microalbuminuria alone in the spot urine sample is more convenient in daily clinical practice and should be used as the screening method for hypertensive patients.
A gain of function p53 mutant promotes both genomic instability and cell survival in a novel p53‐null mammary epithelial cell mode.
Authors: Murphy Kristen L. , Dennis Andrew P. , Rosen Jeffrey M.
Published: July 2002

ABSTRACT Approximately 40% of human breast cancers contain alterations in the tumor suppressor p53. The p53 172R‐H gain‐of‐function mutant (equivalent to the common 175R‐H human breast cancer mutant) has been shown to promote aneuploidy and tumorigenesis in the mammary gland in transgenic mice and may affect genomic stability in part by causing centrosome abnormalities. The precise mechanism of action of these gain‐of‐function mutants is not well understood. and has been studied primarily in fibroblast cell lines. A novel p53‐null mouse mammary epithelial cell line developed from p53‐null mice has been used in adenovirus‐mediated transient transfection experiments to study the properties of this p53 mutant. Marked centrosome amplification and an increased frequency of aberrant mitoses were observed within 72 h of introduction of p53 172R‐H. However. few cells with aberrant centrosome numbers were observed in cells stably expressing the p53 172R‐H mutant. Furthermore. stable expression of this p53 mutant reduced both basal and DNA damage‐induced apoptosis. This result may be mediated in part through abrogation of p73 function. The p53 172R‐H mutant. therefore. appears to influence tumorigenesis at the molecular level in two distinct ways: promoting the development of aneuploidy in cells while also altering their apoptotic response after DNA damage.—Murphy. K. L.. Dennis. A. P.. Rosen. J. M. A gain of function p53 mutant promotes both genomic instability and cell survival in a novel p53‐null mammary epithelial cell model. FASEB J. 14. 2291‐2302 (2000)
Preconditioning regulation of bcl‐2 and p66shc by human NOS1 enhances tolerance to oxidative stress
Authors: Andoh Tsugunobu , Lee Sang Yong , Chiueh Chuang Chin
Published: July 2002

Preconditioning regulation of bcl‐2 and p66shc by human NOS1 enhances tolerance to oxidative stress
Functional and protein chemical characterization of the N‐terminal domain of the rat corticotropin‐releasing factor receptor 1
Authors: Hofmann Bernhard A. , Sydow Sabine , Jahn Olaf , Van Werven Lars , Liepold Thomas , Eckart Klaus , Spiess Joachim
Published: July 2002

Rat corticotropin‐releasing factor receptor 1 (rCRFR1) was produced either in transfected HEK 293 cells as a complex glycosylated protein or in the presence of the mannosidase I inhibitor kifunensine as a high mannose glycosylated protein. The altered glycosylation did not influence the biological function of rCRFR1 as demonstrated by competitive binding of rat urocortin (rUcn) or human/rat corticotropin‐releasing factor (h/rCRF) and agonist‐induced cAMP accumulation. The low production rate of the N‐terminal domain of rCRFR1 (rCRFR1‐NT) by transfected HEK 293 cells, was increased by a factor of 100 in the presence of kifunensine. The product, rCRFR1‐NT‐Kif, bound rUcn specifically (KD = 27 nM) and astressin (KI = 60 nM). This affinity was 10‐fold lower than the affinity of full length rCRFR1. However, it was sufficiently high for rCRFR1‐NT‐Kif to serve as a model for the N‐terminal domain of rCRFR1. With protein fragmentation, Edman degradation, and mass spectrometric analysis, evidence was found for the signal peptide cleavage site C‐terminally to Thr23 and three disulfide bridges between precursor residues 30 and 54, 44 and 87, and 68 and 102. Of all putative N‐glycosylation sites in positions 32, 38, 45, 78, 90, and 98, all Asn residues except for Asn32 were glycosylated to a significant extent. No O‐glycosylation was observed.
A partially folded intermediate conformation is induced in pectate lyase C by the addition of 8‐anilino‐1‐naphthalenesulfonate (ANS)
Authors: Kamen Douglas E. , Woody Robert W.
Published: July 2002

Addition of 8‐anilino‐1‐naphthalenesulfonate (ANS) to acid‐denatured pectate lyase C (pelC) leads to a large increase in the fluorescence quantum yield near 480 nm. The conventional interpretation of such an observation is that the ANS is binding to a partially folded intermediate such as a molten globule. Far‐ultraviolet circular dichroism demonstrates that the enhanced fluorescence results from the induction of a partially folded protein species that adopts a large fraction of native‐like secondary structure on binding ANS. Thus, ANS does not act as a probe to detect a partially folded species, but induces such a species. Near‐ultraviolet circular dichroism suggests that ANS is bound to the protein in a specific conformation. The mechanism of ANS binding and structure induction was probed. The interaction of acid‐unfolded pelC with several ANS analogs was investigated. The results strongly indicate that the combined effects of hydrophobic and electrostatic interactions account for the relatively high binding affinity of ANS for acid‐unfolded pelC. These results demonstrate the need for caution in interpreting enhancement of ANS fluorescence as evidence for the presence of molten globule or other partially folded protein intermediates.
Film dosimetry for intensity modulated radiation therapy: Dosimetric evaluation
Authors: Ju Sang Gyu , Ahn Yong Chan , Huh Seung Jae , Yeo Inhwan Jason
Published: July 2002

X‐ray film has been used for the dosimetry of intensity modulated radiation therapy (IMRT). However, the over‐response of the film to low‐energy photons is a significant problem in photon beam dosimetry, especially in regions outside penumbra. In IMRT, the radiation field consists of multiple small fields and their outside‐penumbra regions; thus, the film dosimetry, for it involves the source of over‐response in its radiation field. In this study we aim to verify and possibly improve film dosimetry for IMRT. Two types of modulated beams were constructed by combining five to seven different static radiation fields using 6 MV x rays. For verifying film dosimetry, x‐ray films and an ion chamber were used to measure dose profiles at various depths in a phantom. The film setups include both parallel and perpendicular arrangements against the beam incident direction. In addition, to reduce an over‐response, we placed 0.01 in. (0.25 mm) thick lead filters on both sides of the film. Compared with ion‐chamber measurement, measured dose profiles showed the film over‐response at outside‐penumbra and low‐dose regions. The error increased with depths and approached 15% as a maximum for the field size of at 10 cm depth. The use of filters reduced the error down to 3%. In this study we demonstrated that film dosimetry for IMRT involves sources of error due to its over‐response to low‐energy photons, with the error most transparent in the low‐dose region. The use of filters could enhance the accuracy in film dosimetry for IMRT. In this regard, the use of an optimal filter condition is recommended.
Is the indicator dilution theory really the adequate base of many blood flow measurement techniques?
Authors: Doriot P.‐A. , Dorsaz P.‐A. , Dorsaz L. , Rutishauser W. J.
Published: July 2002

The indicator dilution theory is the underlying model of many blood flow measurement techniques used daily in hospitals, for instance in cardiac catheterization laboratories. The basic version of this theory applies to a “stationary” flow system with one inlet and one outlet, into which a small amount of indicator is injected “suddenly” at time at the inlet. The quintessence of the theory consists in three equations, which themselves result from some apparently simple assumptions about the considered flow systems. The first equation states that the (constant) flow through the system can be calculated by use of the known amount of indicator, and of the indicator concentration‐time curve recorded at the outlet. The second one allows the calculation of the “mean transit time” of fluid and indicator particles through the system from the curve The third equation, yields the system volume It is generally believed that these three equations would be absolutely valid if the assumptions of the theory could be perfectly fulfilled. We show, by considering a simple model, that all three equations are actually incorrect for most flow systems when the detector used to record the curve is of the “trans‐illumination” type, as is the case for instance in dye dilution methods and in many angiographic or CT techniques. A further consequence is that which is truly the “center of mass” of the concentration‐time curve does not have the well known property of being the adequate parameter for flow determinations. Many flow measurement techniques thus appear to have no theoretical base.
Time-domain simulation of damped impacted plates. I. Theory and experiments
Authors: Chaigne Antoine , Lambourg Christophe
Published: July 2002

A time-domain formulation for the flexural vibrations in damped rectangular isotropic and orthotropic plates is developed, in order to investigate transient excitation of plates by means of sound synthesis. The model includes three basic mechanisms of damping (thermoelasticity, viscoelasticity and radiation) using a general differential operator. The four rigidity factors of the plate are modified by perturbation terms, each term corresponding to one specific damping mechanism. The first damping term is derived from the coupling between the thermoelastic stress–strain relations and the heat diffusion equation. The second term is obtained from the general differential formulation of viscoelasticity. The third term is obtained through a Padé approximation of the damping factor which governs the coupling of the plate with the surrounding air. The decay factors predicted by the model reproduce adequately the dependence on both dimensions and frequency of the decay factors measured on rectangular plates of various sizes and thicknesses made of four different materials (aluminum, glass, carbon fiber, and wood). The numerical resolution of the complete problem, including initial and boundary conditions, and the comparison between real and simulated sounds are presented in a companion paper [J. Acoust. Soc. Am. 109, 1433–1447 (2000)].
Application of three-dimensional resonant acoustic spectroscopy method to rock and building materials
Authors: Ostrovsky Lev , Lebedev Andrey , Matveyev Alexander , Potapov Andrey , Sutin Alexander , Soustova Irina , Johnson Paul
Published: July 2002

This paper presents the experimental and theoretical results of applying resonant acoustic spectroscopy (RAS) to determine elastic parameters and losses in such consolidated granular materials as rock and building bricks. First, the theoretical aspects of the RAS method are outlined. A computer code for the rectangular and cylindrical samples was developed and tested. The results of experiments on specimens of rock and ceramic brick are then described. Finally, a modification of the previously published RUS algorithm is presented which permits a significant reduction in computing time for elongated samples.
Aircraft flight parameter estimation based on passive acoustic techniques using the polynomial Wigner–Ville distribution
Authors: Reid David C. , Zoubir Abdelhak M. , Boashash Boualem
Published: July 2002

The acoustic signal from an overflying aircraft, as heard by a stationary observer, is used to estimate an aircraft’s constant height, ground speed, range, and acoustic frequency. Central to the success of this flight parameter estimation scheme is the need for an accurate estimate of the instantaneous frequency of the observed acoustic signal. In this paper, the polynomial Wigner–Ville distribution is used in this application as the instantaneous frequency estimator. Its performance and the issue of the optimal time domain window length are addressed.
Acoustic wave propagation through porous media: Theory and experiments
Authors: Geerits Tim W. , Kelder Oscar
Published: July 2002

A new lossless poroelastic wave propagation theory is verified by means of ultrasonic transmission measurements on artificial rock samples in a water-filled tank. The experiments involved are similar to those performed by Plona [Appl. Phys. Lett. 36, 259–261 (1980)]. In this physically and mathematically mutual consistent new theory the coupling terms between the fluid and solid phase of the porous medium are completely determined by the measured wave speeds and the mass densities and constitutive parameters of both constituting phases. Verification of the amplitudes of the received bulk waves in both the time domain and frequency domain provide information on the validity of the combined effect of propagation characteristics and new macroscopic fluid/fluid-saturated-rock boundary conditions resulting from this theory. The comparison technique between theory and experiments is based on the Fraunhofer diffraction theory, and is first tested in a perfectly elastic medium transmission configuration. Subsequently, this comparison technique is used for the poroelastic medium. It is shown that this technique is very accurate and reliable. The experimental results for the compressional wave and the shear wave in the perfectly elastic medium are in excellent agreement with the theoretical predictions. For the fluid-saturated porous samples, good agreement is found only for the fast compressional wave. For both the shear wave and the slow compressional, it is obvious that there is some kind of loss mechanism involved, which cannot be explained by the current theory. Despite the fact that the bulk losses in the porous medium can be explained qualitatively by the full frequency range Biot theory, it is conjectured that even a quantitative fit is feasible if Johnson’s loss model [D. L. Johnson et al., J. Fluid Mech. 176, 379–402 (1987)] is applied in the lossy counterpart of the current theory [T. W. Geerits, J. Acoust. Soc. Am. 100, 2949–2959 (1996)].