bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimizing the Setup of the BRISP Spectrometer by Upgraded McStas Simulations
Authors: Venturi G. , Guarini E. , Formisano F. , Orecchini A. , Cunsolo A. , Petrillo C. , Sacchetti F. , Barocchi F.
Published: April 2004

Here we report on new results obtained by ad hoc developed McStas simulations of the time-of-flight thermal neutron Brillouin spectrometer BRISP, presently under construction at the ILL. In such a spectrometer a double-curvature focusing monochromator is combined with a multi-beam converging collimator. This configuration, first exploited for BRISP, has been carefully analyzed by developing new specific McStas codes which enable a reliable simulation of the real components, including the detailed features of the monochromator, the background disk-chopper and the honeycomb converging collimator. The present McStas calculations are also used as a guide to refine technical details, such as the optimal arrangement of the crystals on the monochromator surface as a function of the measured mosaic spread. The simulation results are consistent with the expected estimates of both intensity and resolution, and show that BRISP can provide new opportunities for advanced investigations of the low-Q dynamics of disordered and magnetic systems.
Verbal Deficits and Disruptive Behavior Disorders among Children of Opiate‐Dependent Parents
Authors: Wilson Jeffrey J. , Nunes Edward V. , Greenwald Steven , Weissman Myrna
Published: April 2004

In order to explore the association between verbal deficits and disruptive behavior disorders among children of addicted parents, 283 6—17‐year‐old children and their opiate‐dependent parents completed diagnostic interviews and standardized measures of vocabulary. Unexpectedly, racial differences in the scores confounded the exploration of the relationship between cognitive scores and disruptive behavior disorders. An interaction between disruptive behavior disorder and race is explored; among Caucasian youths, low verbal scores are associated with disruptive behavior disorders, but this association was not found among African‐ and Hispanic‐American youths. Further analysis and research are needed to understand the clinical significance of relationships between verbal deficits and disruptive behavior disorders within racially diverse groups. (Am J Addict 2004;13:202–212)
Boundedness and oscillation for nonlinear dynamic equations on a time scale
Authors: Erbe Lynn , Peterson Allan
Published: April 2004

We obtain some boundedness and oscillation criteria for solutions to the nonlinear dynamic equation
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="left-parenthesis p left-parenthesis t right-parenthesis x Superscript normal upper Delta Baseline left-parenthesis t right-parenthesis right-parenthesis Superscript normal upper Delta Baseline plus q left-parenthesis t right-parenthesis left-parenthesis f ring x Superscript sigma Baseline right-parenthesis equals 0 comma">

(
p
(
t
)

x

Δ

(
t
)

)

Δ

+
q
(
t
)
(
f
∘

x

σ

)
=
0
,

(p(t)x^{\Delta }(t))^{\Delta }+q(t)(f\circ x^{\sigma })=0,

\]
on time scales. In particular, no explicit sign assumptions are made with respect to the coefficient

q
(
t
)

q(t)

. We illustrate the results by several examples, including a nonlinear Emden–Fowler dynamic equation.
The Cauchy problem for a class of Kovalevskian pseudo-differential operators
Authors: Agliardi Rossella , Cicognani Massimo
Published: April 2004

We prove the

H

∞

H^{\infty }

well-posedness of the forward Cauchy problem for a pseudo-differential operator

P
P

of order

m
≥
2

m\geq 2

with the Log-Lipschitz continuous symbol in the time variable. The characteristic roots

λ
k

\lambda _k

of

P
P

are distinct and satisfy the necessary Lax-Mizohata condition Im

λ
k

≥
0

\lambda _k\geq 0

. The Log-Lipschitz regularity has been tested as the optimal one for

H

∞

H^{\infty }

well-posedness in the case of second-order hyperbolic operators. Our main aim is to present a simple proof which needs only a little of the basic calculus of standard pseudo-differential operators.
Approximate fixed point sequences and convergence theorems for Lipschitz pseudocontractive maps
Authors: Chidume C. , Zegeye H.
Published: April 2004

Let

K
K

be a nonempty closed convex subset of a real Banach space

E
E

and

T
T

be a Lipschitz pseudocontractive self-map of

K
K

with

F
(
T
)
:=
{
x
∈
K
:
T
x
=
x
}
≠
∅

F(T):=\{x\in K:Tx=x\}\neq \emptyset

. An iterative sequence

{

x
n

}

\{x_n\}

is constructed for which

|

|

x
n

−
T

x
n

|

|

→
0

||x_n-Tx_n||\rightarrow 0

as

n
→
∞

n\rightarrow \infty

. If, in addition,

K
K

is assumed to be bounded, this conclusion still holds without the requirement that

F
(
T
)
≠
∅
.

F(T)\neq \emptyset .

Moreover, if, in addition,

E
E

has a uniformly Gâteaux differentiable norm and is such that every closed bounded convex subset of

K
K

has the fixed point property for nonexpansive self-mappings, then the sequence

{

x
n

}

\{x_n\}

converges strongly to a fixed point of

T
T

. Our iteration method is of independent interest.
2𝑆₄*𝑄₈-extensions in characteristic 3
Authors: Crespo Teresa
Published: April 2004

We present an explicit construction of the complete family of Galois extensions of a field

K
K

of characteristic 3 with Galois group the central product

2

S
4

∗

Q
8

2S_4* Q_8

of a double cover

2

S
4

2S_4

of the symmetric group

S
4

S_4

and the quaternion group

Q
8

Q_8

, containing a given

S
4

S_4

-extension of the field

K
K

.
On the invariance of classes Φ𝐵𝑉,Λ𝐵𝑉 under composition
Authors: Pierce Pamela , Waterman Daniel
Published: April 2004

The necessary and sufficient condition for

g
∘
f

g \circ f

to be in the class

Φ
B
V
,
Λ
B
V

\Phi BV, \Lambda BV

for every

f
f

of that class whose range is in the domain of

g
g

is that

g
g

be in

Lip
⁡
1

\operatorname {Lip}1

.
Biliaison classes of curves in 𝐏³
Authors: Strano Rosario
Published: April 2004

We characterize the curves in

P

3

{\mathbf {P}}^{3}

that are minimal in their biliaison class. Such curves are exactly the curves that do not admit an elementary descending biliaison. As a consequence we have that every curve in

P

3

{\mathbf {P}}^{3}

can be obtained from a minimal one by means of a finite sequence of ascending elementary biliaisons.
Symmetric word equations in two positive definite letters
Authors: Hillar Christopher , Johnson Charles
Published: April 2004

For every symmetric (“palindromic") word

S
(
A
,
B
)

S(A,B)

in two positive definite letters and for each fixed

n
n

-by-

n
n

positive definite

B
B

and

P
P

, it is shown that the symmetric word equation

S
(
A
,
B
)
=
P

S(A,B) = P

has an

n
n

-by-

n
n

positive definite solution

A
A

. Moreover, if

B
B

and

P
P

are real, there is a real solution

A
A

. The notion of symmetric word is generalized to allow non-integer exponents, with certain limitations. In some cases, the solution

A
A

is unique, but, in general, uniqueness is an open question. Applications and methods for finding solutions are also discussed.
Robust transitivity and topological mixing for 𝐶¹-flows
Authors: Abdenur Flavio , Avila Artur , Bochi Jairo
Published: April 2004

We prove that nontrivial homoclinic classes of

C
r

C^r

-generic flows are topologically mixing. This implies that given

Λ
\Lambda

, a nontrivial

C
1

C^1

-robustly transitive set of a vector field

X
X

, there is a

C
1

C^1

-perturbation

Y
Y

of

X
X

such that the continuation

Λ
Y

\Lambda _Y

of

Λ
\Lambda

is a topologically mixing set for

Y
Y

. In particular, robustly transitive flows become topologically mixing after

C
1

C^1

-perturbations. These results generalize a theorem by Bowen on the basic sets of generic Axiom A flows. We also show that the set of flows whose nontrivial homoclinic classes are topologically mixing is not open and dense, in general.
Nonnegative unitary operators
Authors: Förster K.-H. , Nagy B.
Published: April 2004

Unitary operators in Hilbert space map an orthonormal basis onto another. In this paper we study those that map an orthonormal basis onto itself. We show that a sequence of cardinal numbers is a complete set of unitary invariants for such an operator. We obtain a characterization of these operators in terms of their spectral properties. We show how much simpler the structure is in finite-dimensional space, and also describe the structure of certain isometries in Hilbert space.
Commutants of Bol loops of odd order
Authors: Kinyon Michael , Phillips J.
Published: April 2004

In this note we show that the commutant of a Bol loop of odd order is a subloop.
An estimate for the number of bound states of the Schrödinger operator in two dimensions
Authors: Stoiciu Mihai
Published: April 2004

For the Schrödinger operator

−
Δ
+
V

-\Delta + V

on

R

2

\mathbb R ^2

let

N
(
V
)

N(V)

be the number of bound states. One obtains the following estimate:
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper N left-parenthesis upper V right-parenthesis less-than-or-equal-to 1 plus integral Underscript double-struck upper R squared Endscripts integral Underscript double-struck upper R squared Endscripts StartAbsoluteValue upper V left-parenthesis x right-parenthesis EndAbsoluteValue StartAbsoluteValue upper V left-parenthesis y right-parenthesis EndAbsoluteValue StartAbsoluteValue upper C 1 ln EndAbsoluteValue x minus y StartAbsoluteValue plus upper C 2 EndAbsoluteValue squared d x d y">

N
(
V
)
≤
 
1
 
+

∫

R

2

∫

R

2

|

V
(
x
)

|

 

|

V
(
y
)

|

 

|

C
1

ln
⁡

|

x
−
y

|

+

C
2

|

2

 
d
x

d
y

N(V) \leq \ 1 \ + \int _{\mathbb R ^2} \int _{\mathbb R ^2} |V(x)| \ |V(y)| \ |C_1 \ln |x-y| + C_2|^2 \ dx\,dy

\]
where

C
1

=
−

1

2
π

C_1 = -\frac {1}{2\pi }

and

C
2

=

ln
⁡
2
−
γ

2
π

C_2 = \frac {\ln 2 - \gamma }{2 \pi }

(

γ
\gamma

is the Euler constant). This estimate holds for all potentials for which the previous integral is finite.
Dendrites and light mappings
Authors: Charatonik Janusz , Krupski Paweł
Published: April 2004

It is shown that a metric continuum

X
X

is a dendrite if and only if for every compact space (continuum)

Y
Y

and for every light confluent mapping

f
:
Y
→
f
(
Y
)

f: Y \to f(Y)

such that

X
⊂
f
(
Y
)

X \subset f(Y)

there is a copy

X
′

X’

of

X
X

in

Y
Y

for which the restriction

f

|

X
′

:

X
′

→
X

f|X’: X’ \to X

is a homeomorphism. As a corollary it follows that only dendrites have the lifting property with respect to light confluent mappings. Other classes of mappings

f
f

are also discussed. This is a continuation of a previous study by the authors (2000), where open mappings

f
f

were considered.
On some special polynomials
Authors: Karachik V.
Published: April 2004

New special functions called

G
G

-functions are introduced. Connections of

G
G

-functions with the known Legendre, Chebyshev and Gegenbauer polynomials are given. For

G
G

-functions the Rodrigues formula is obtained.
Sebestyén moment problem: The multi-dimensional case
Authors: Popovici Dan , Sebestyén Zoltán
Published: April 2004

Given a family

{

h

n

}

n

∈

Z

+
Ω

\{h_{\mathbf {n}}\}_{\mathbf {n}\in \mathbb {Z}_+^\Omega }

of vectors in a Hilbert space

H

\mathcal {H}

we characterize the existence of a family of commuting contractions

T

=
{

T
ω

}

w
∈
Ω

\mathbf {T}=\{T_\omega \}_{w\in \Omega }

on

H

\mathcal {H}

having regular dilation and such that

h

n

=

T

n

h

0

,

n

∈

Z

+
Ω

.

\begin{equation*} h_{\mathbf {n}}=\mathbf {T} ^{\mathbf {n}} h_{\mathbf {0}},\quad \mathbf {n}\in \mathbb {Z}_+^\Omega . \end{equation*}

The theorem is a multi-dimensional analogue for some well-known operator moment problems due to Sebestyén in case

|

Ω

|

=
1

|\Omega |=1

or, recently, to Găvruţă and Păunescu in case

|

Ω

|

=
2

|\Omega |=2

.
Superdecomposable pure-injective modules exist over some string algebras
Authors: Puninski Gena
Published: April 2004

We prove that over every non-domestic string algebra over a countable field there exists a superdecomposable pure-injective module.
Primes generated by elliptic curves
Authors: Everest Graham , Miller Victor , Stephens Nelson
Published: April 2004

For a rational elliptic curve in Weierstrass form, Chudnovsky and Chudnovsky considered the likelihood that the denominators of the

x
x

-coordinates of the multiples of a rational point are squares of primes. Assuming the point is the image of a rational point under an isogeny, we use Siegel’s Theorem to prove that only finitely many primes will arise. The same question is considered for elliptic curves in homogeneous form, prompting a visit to Ramanujan’s famous taxi-cab equation. Finiteness is provable for these curves with no extra assumptions. Finally, consideration is given to the possibilities for prime generation in higher rank.
Zero product preserving maps of operator-valued functions
Authors: Ke Wen-Fong , Li Bing-Ren , Wong Ngai-Ching
Published: April 2004

Let

X
,
Y

X,Y

be locally compact Hausdorff spaces and

M

{\mathcal M}

,

N

{\mathcal N}

be Banach algebras. Let

θ
:

C
0

(
X
,

M

)
→

C
0

(
Y
,

N

)

\theta : C_0(X,{\mathcal M}) \to C_0(Y, {\mathcal N})

be a zero product preserving bounded linear map with dense range. We show that

θ
\theta

is given by a continuous field of algebra homomorphisms from

M

{\mathcal M}

into

N

{\mathcal N}

if

N

{\mathcal N}

is irreducible. As corollaries, such a surjective

θ
\theta

arises from an algebra homomorphism, provided that

M

{\mathcal M}

is a

W
∗

W^*

-algebra and

N

{\mathcal N}

is a semi-simple Banach algebra, or both

M

{\mathcal M}

and

N

{\mathcal N}

are

C
∗

C^*

-algebras.
Reflection symmetries and absence of eigenvalues for one-dimensional Schrödinger operators
Authors: Damanik David , Hundertmark Dirk
Published: April 2004

We prove a criterion for absence of decaying solutions for one-dimensional Schrödinger operators. As necessary input, we require infinitely many centers of local reflection symmetry and upper and lower bounds for the traces of the associated transfer matrices.
Diffusions, exit time moments and Weierstrass theorems
Authors: de la Peña Victor , McDonald Patrick
Published: April 2004

Let

X
t

X_t

be a one-dimensional diffusion with infinitesimal generator given by the operator

L
=

1
2

(
a
(
x
)

d

d
x

)
2

+
b
(
x
)

d

d
x

L = \frac 12 (a(x) \frac {d}{dx})^2 + b(x) \frac {d}{dx}

where

a
(
x
)

a(x)

is a smooth, positive real-valued function and the ratio of

a
(
x
)

a(x)

and

b
(
x
)

b(x)

is a constant. Given a compact interval, we prove a Weierstrass-type theorem for the exit time moments of

X
t

X_t

and their corresponding (naturally weighted) first derivatives, and we provide an algorithm that produces uniform approximations of arbitrary continuous functions by exit time moments. We investigate analogues of these results in higher-dimensional Euclidean spaces. We give expansions for several families of special functions in terms of exit time moments.
Exponents of class groups of real quadratic function fields
Authors: Chakraborty Kalyan , Mukhopadhyay Anirban
Published: April 2004

We show that there are

≫

q

l

/

(
2
g
)

\gg q^{l/(2g)}

polynomials

D
∈

F

q

[
t
]

D\in \mathbb {F}_q[t]

with

deg
⁡
(
D
)
≤
l

\deg (D)\le l

such that the ideal class group of the real quadratic extensions

F

q

(
t
,

D

)

\mathbb {F}_q(t,\sqrt D)

has an element of order

g
g

.
The hereditary discrepancy is nearly independent of the number of colors
Authors: Doerr Benjamin
Published: April 2004

We investigate the discrepancy (or balanced coloring) problem for hypergraphs and matrices in arbitrary numbers of colors. We show that the hereditary discrepancy in two different numbers

a
,
b
∈

N

≥
2

a, b \in {\mathbb N} _{\ge 2}

of colors is the same apart from constant factors, i.e.,
\[

herdisc
⁡
(
⋅
,

b

)
=
Θ
(
herdisc
⁡
(
⋅
,

a

)
)
.

\operatorname {herdisc}(\cdot ,{b}) = \Theta ( \operatorname {herdisc}(\cdot ,{a})).

\]
This contrasts the ordinary discrepancy problem, where no correlation exists in many cases.
On the norm of an idempotent Schur multiplier on the Schatten class
Authors: Banks William , Harcharras Asma
Published: April 2004

We show that if the norm of an idempotent Schur multiplier on the Schatten class

S
p

S^p

lies sufficiently close to

1
1

, then it is necessarily equal to 

1
1

. We also give a simple characterization of those idempotent Schur multipliers on

S
p

S^p

whose norm is

1
1

.
On cleavability of continua over LOTS
Authors: Buzyakova Raushan
Published: April 2004

It is shown that any continuum cleavable over a LOTS

L
L

is embeddable into

L
L

.
Domaine numérique du produit et de la bimultiplication 𝑀_{2,𝐴,𝐵}
Authors: Kaadoud Mohamed
Published: April 2004

In this paper, we present an extension of Bouldin’s result (1970) concerning the numerical range

W
(
A
B
)

W(AB)

of the product of two operators

A
A

and

B
B

that are commuting and for which one of the set

W
(
A
)

W(A)

or

W
(
B
)

W(B)

consists of positive numbers. We also prove that if

A
A

or

B
B

is a subnormal operator on a separable Hilbert space, then
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="ModifyingAbove upper W left-parenthesis upper M Subscript 2 comma upper A comma upper B Baseline right-parenthesis With bar equals ModifyingAbove c o left-bracket upper W left-parenthesis upper A right-parenthesis upper W left-parenthesis upper B right-parenthesis right-bracket With bar comma">

W
(

M

2
,
A
,
B

)

¯

=

c
o

[
W
(
A
)
W
(
B
)
]

¯

,

\begin{equation*} \overline {W(M_{2,A,B})}=\overline {co\left [ W(A)W(B)\right ] }, \end{equation*}

where

M

2
,
A
,
B

M_{2,A,B}

is the operator bimultiplication and

c
o

co

is the convex hull. Résumé. Dans ce travail, nous améliorons un résultat de Bouldin (1970) concernant la localisation de

W
(
A
B
)
,

W(AB),

le domaine numérique du produit de deux opérateurs

A
A

et

B
B

sur un espace de Hilbert lorsque

A
A

et

B
B

commutent et

W
(
A
)

W(A)

est constitué de réels strictement positifs. Dans le cas où

A
A

ou

B
B

est un opérateur sous normal sur un espace de Hilbert séparable, nous montrons que
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="ModifyingAbove upper W left-parenthesis upper M Subscript 2 comma upper A comma upper B Baseline right-parenthesis With bar equals ModifyingAbove c o left-bracket upper W left-parenthesis upper A right-parenthesis upper W left-parenthesis upper B right-parenthesis right-bracket With bar comma">

W
(

M

2
,
A
,
B

)

¯

=

c
o

[
W
(
A
)
W
(
B
)
]

¯

,

\begin{equation*} \overline {W(M_{2,A,B})}=\overline {co\left [ W(A)W(B)\right ] }, \end{equation*}

où

M

2
,
A
,
B

M_{2,A,B}

est l’opérateur produit ou bimultiplication et

c
o

co

est l’enveloppe convexe.
Functional analysis proofs of Abel’s theorems
Authors: Karaev M.
Published: April 2004

We give alternative proofs to the classical theorems of Abel, using the concept of Berezin symbol.
A strong Lebesgue point property for Sobolev functions
Authors: Latvala Visa
Published: April 2004

We show that first-order Sobolev functions fulfill a Wiener integral type Lebesgue point property outside a set of Sobolev capacity zero. Our condition is stronger than the standard Lebesgue point property, but the exceptional set is slightly larger.
Mycielski ideal and the perfect set theorem
Authors: Repický Miroslav
Published: April 2004

We make several observations on the Mycielski ideal and prove a version of the perfect set theorem concerning this ideal for analytic sets: If

A
⊆

ω

2

A\subseteq {}^\omega 2

is an analytic set all projections of which are uncountable, then there is a perfect set

B
⊆
A

B\subseteq A

a projection of which is the whole space. We also prove that (a modification of) an infinite game of Mycielski is determined for analytic sets.
Fixed point formula for holomorphic functions
Authors: Tarkhanov Nikolai
Published: April 2004

We show a Lefschetz fixed point formula for holomorphic functions in a bounded domain

D

\mathcal {D}

with smooth boundary in the complex plane. To introduce the Lefschetz number for a holomorphic map of

D

\mathcal {D}

, we make use of the Bergman kernel of this domain. The Lefschetz number is proved to be the sum of the usual contributions of fixed points of the map in

D

\mathcal {D}

and contributions of boundary fixed points, these latter being different for attracting and repulsing fixed points.
Maximal invariant subspaces for 𝐴²_{𝛼}(𝐷)
Authors: Trent Tavan
Published: April 2004

We find the maximal invariant subspaces for

M
z

M_z

on

C

n

\mathbb {C}^n

-valued Bergman-type spaces.
The numerical range of a nilpotent operator on a Hilbert space
Authors: Karaev Mubariz
Published: April 2004

We prove that the numerical range

W

(
N
)

W\left ( N\right )

of an arbitrary nilpotent operator

N
N

on a complex Hilbert space

H
H

is a circle (open or closed) with center at

0
0

and radius not exceeding

‖
N
‖

cos
⁡

π

n
+
1

,

\left \| N\right \| \cos \frac {\pi }{n+1},

where

n
n

is the power of nilpotency of

N
.

N.
The positivity of linear functionals on Cuntz algebras associated to unit vectors
Authors: Lee Jung-Rye , Shin Dong-Yun
Published: April 2004

We study the linear functional

ρ
\rho

on the Cuntz algebra

O

n

\mathcal {O}_{n}

associated to a sequence

⟨

η

m

⟩

\langle \eta _{m} \rangle

of unit vectors

η

m

\eta _{m}

in

C

n

\mathbb {C}^{n}

that is a generalization of the Cuntz state. We prove that

ρ
\rho

is positive if and only if

⟨

η

m

⟩

\langle \eta _{m} \rangle

is a constant sequence.
Euler number of the moduli space of sheaves on a rational nodal curve
Authors: Wu Baosen
Published: April 2004

In this paper, we use finite group actions to compute the Euler number of the moduli space of rank 2 stable sheaves on a rational nodal curve.
On the discrete groups of Moonshine
Authors: Conway John , McKay John , Sebbar Abdellah
Published: April 2004

We characterize the 171 discrete subgroups of

PSL

2

(

R

)

\mbox {PSL}_2(\mathbb {R})

occurring in Monstrous Moonshine in terms of their group-theoretic properties alone.
Extensions contained in ideals
Authors: Kucerovsky Dan
Published: April 2004

We prove a Weyl-von Neumann type absorption theorem for extensions which are not full, and give a condition for constructing infinite repeats contained in an ideal. We also clear up some questions associated with the purely large criterion for full extensions to be absorbing.
Metrical diophantine approximation for continued fraction like maps of the interval
Authors: Haas Andrew , Molnar David
Published: April 2004

We study the metrical properties of a class of continued fraction-like mappings of the unit interval, each of which is defined as the fractional part of a Möbius transformation taking the endpoints of the interval to zero and infinity.
Combinatorial properties of Thompson’s group 𝐹
Authors: Cleary Sean , Taback Jennifer
Published: April 2004

We study some combinatorial consequences of Blake Fordham’s theorems on the word metric of Thompson’s group

F
F

in the standard two generator presentation. We explore connections between the tree pair diagram representing an element

w
w

of

F
F

, its normal form in the infinite presentation, its word length, and minimal length representatives of it. We estimate word length in terms of the number and type of carets in the tree pair diagram and show sharpness of those estimates. In addition we explore some properties of the Cayley graph of

F
F

with respect to the two generator finite presentation. Namely, we exhibit the form of “dead end” elements in this Cayley graph, and show that it has no “deep pockets”. Finally, we discuss a simple method for constructing minimal length representatives for strictly positive or negative words.
Maps between non-commutative spaces
Authors: Smith S.
Published: April 2004

Let

J
J

be a graded ideal in a not necessarily commutative graded

k
k

-algebra

A
=

A
0

⊕

A
1

⊕
⋯

A=A_0 \oplus A_1 \oplus \cdots

in which

dim
k

⁡

A
i

>
∞

\dim _k A_i > \infty

for all

i
i

. We show that the map

A
→
A

/

J

A \to A/J

induces a closed immersion

i
:

Proj

n
c

⁡
A

/

J
→

Proj

n
c

⁡
A

i:\operatorname {Proj}_{nc} A/J \to \operatorname {Proj}_{nc}A

between the non-commutative projective spaces with homogeneous coordinate rings

A
A

and

A

/

J

A/J

. We also examine two other kinds of maps between non-commutative spaces. First, a homomorphism

ϕ
:
A
→
B

\phi :A \to B

between not necessarily commutative

N

\mathbb {N}

-graded rings induces an affine map

Proj

n
c

⁡
B
⊃
U
→

Proj

n
c

⁡
A

\operatorname {Proj}_{nc} B \supset U \to \operatorname {Proj}_{nc} A

from a non-empty open subspace

U
⊂

Proj

n
c

⁡
B

U \subset \operatorname {Proj}_{nc} B

. Second, if

A
A

is a right noetherian connected graded algebra (not necessarily generated in degree one), and

A

(
n
)

A^{(n)}

is a Veronese subalgebra of

A
A

, there is a map

Proj

n
c

⁡
A
→

Proj

n
c

⁡

A

(
n
)

\operatorname {Proj}_{nc} A \to \operatorname {Proj}_{nc} A^{(n)}

; we identify open subspaces on which this map is an isomorphism. Applying these general results when

A
A

is (a quotient of) a weighted polynomial ring produces a non-commutative resolution of (a closed subscheme of) a weighted projective space.
Universal covers for Hausdorff limits of noncompact spaces
Authors: Sormani Christina , Wei Guofang
Published: April 2004

We prove that if

Y
Y

is the Gromov-Hausdorff limit of a sequence of complete manifolds,

M
i
n

M^n_i

, with a uniform lower bound on Ricci curvature, then

Y
Y

has a universal cover.
Dynamical approach to some problems in integral geometry
Authors: Paneah Boris
Published: April 2004

As is well known, the main problem in integral geometry is to reconstruct a function in a given domain

D
D

, where its integrals over a family of subdomains in

D
D

are known. Such a problem is interesting not only as an object of pure analysis, but also in connection with various applications in practical disciplines. The most remarkable example of such a connection is the Radon problem and tomography. In this paper we solve one of these problems when

D
D

is a bounded domain in

R

2

{\mathbb {R}}^2

with a piecewise smooth boundary. Some intermediate results related to dynamical systems with two generators and to some functional-integral equations are new and interesting per se. As an application of the results obtained we briefly study a boundary problem for a general third order hyperbolic partial differential equation in a bounded domain

D
⊂

R

2

D\subset {\mathbb {R}}^2

with data on the whole boundary

∂
D

\partial D

.
Sums of squares in real rings
Authors: Fernando José , Ruiz Jesús , Scheiderer Claus
Published: April 2004

Let

A
A

be an excellent ring. We show that if the real dimension of

A
A

is at least three then

A
A

has infinite Pythagoras number, and there exists a positive semidefinite element in

A
A

which is not a sum of squares in

A
A

.
Character degree graphs and normal subgroups
Authors: Isaacs I.
Published: April 2004

We consider the degrees of those irreducible characters of a group

G
G

whose kernels do not contain a given normal subgroup

N
N

. We show that if

N
⊆

G
′

N \subseteq G’

and

N
N

is not perfect, then the common-divisor graph on this set of integers has at most two connected components. Also, if

N
N

is solvable, we obtain bounds on the diameters of the components of this graph and, in the disconnected case, we study the structure of

N
N

and of

G
G

.
Riemann’s zeta function and beyond
Authors: Gelbart Stephen , Miller Stephen
Published: April 2004

In recent yearsLL-functions and their analytic properties have assumed a central role in number theory and automorphic forms. In this expository article, we describe the two major methods for proving the analytic continuation and functional equations ofLL-functions: the method of integral representations, and the method of Fourier expansions of Eisenstein series. Special attention is paid to technical properties, such as boundedness in vertical strips; these are essential in applying the converse theorem, a powerful tool that uses analytic properties ofLL-functions to establish cases of Langlands functoriality conjectures. We conclude by describing striking recent results which rest upon the analytic properties ofLL-functions.
The wave maps equation
Authors: Tataru Daniel
Published: April 2004

The wave maps equation has become a very popular topic in recent years. The aim of these expository notes is to present a non-technical survey of the ideas and methods which have proved useful in the study of wave maps, leading up to the latest results. The remaining open problems are also stated and explained.
Completing Lie algebra actions to Lie group actions
Authors: Kamber Franz , Michor Peter
Published: April 2004

For a finite-dimensional Lie algebrag\mathfrak {g}of vector fields on a manifoldMMwe show thatMMcan be completed to aGG-space in a universal way, which however is neither Hausdorff norT1T_1in general. HereGGis a connected Lie group with Lie-algebrag\mathfrak {g}. For a transitiveg\mathfrak {g}-action the completion is of the formG/HG/Hfor a Lie subgroupHHwhich need not be closed. In general the completion can be constructed by completing eachg\mathfrak {g}-orbit.
Endoscopic decomposition of characters of certain cuspidal representations
Authors: Kazhdan David , Varshavsky Yakov
Published: April 2004

We construct an endoscopic decomposition for local

L
L

-packets associated to irreducible cuspidal Deligne-Lusztig representations. Moreover, the obtained decomposition is compatible with inner twistings.
Impaired Vascular Reactivity of Isolated Rat Middle Cerebral Artery after Cortical Spreading Depression in Vivo
Authors: Seitz Iris , Dirnagl Ulrich , Lindauer Ute
Published: April 2004

Cortical spreading depression (CSD) is accompanied by hyperemia followed by long-lasting hypoperfusion and impaired cerebrovascular reactivity. The authors show that vasodilation to extraluminal acidosis (pH 7.0) and increased concentrations of extraluminal potassium (12, 20, 40 mmol/L) was significantly reduced in isolated rat middle cerebral arteries after CSD in vivo before the artery was isolated, compared with sham-operated controls. Application of 80-mmol/L potassium induced vasoconstriction after CSD. Therefore, the impairment of vascular reactivity after CSD in vivo occurs, at least in part, at the vascular level itself.
Characterization of BrdU-Positive Neurons Induced by Transient Global Ischemia in Adult Hippocampus
Authors: Kawai Takayuki , Takagi Norio , Miyake-Takagi Keiko , Okuyama Noriko , Mochizuki Nobuyuki , Takeo Satoshi
Published: April 2004

Neurogenesis in the brain continues throughout life and is promoted by brain insults including ischemia. There is no critical conclusion, however, about whether proliferated cells acquire neuronal function after ischemia. Transient global ischemia was produced by a four-vessel occlusion procedure in rats (n = 54). To label proliferative cells, rats were administrated with a single dose of 5-bromo-2’-deoxyuridine (BrdU) at 4, 6, 8, 10, 13, or 15 days after ischemia. Increases in BrdU-positive cells were detected in the hippocampal dentate gyrus at 5, 7, and 9 days after ischemia. To determine the phenotype of BrdU-positive cells, BrdU was administrated twice daily for 3 consecutive days during 6 to 8 days after ischemia. A basic helix–loop–helix transcription factor NeuroD at 7 and 14 days and an immature migrating neuronal marker doublecortin at 14 days after ischemia were expressed transiently in proliferative cells. These proliferative cells after ischemia differentiated to the phenotype of neuron at 28 days after ischemia. Furthermore, BrdU-positive neurons showed phosphorylation of extracellular signal-regulated kinase (ERK) by intracerebroventricular injection of N-methyl-D-aspartate (NMDA) at 28 and 56 days after ischemia as seen in surrounding mature neurons. The number of BrdU-positive neurons, which responded to NMDA stimulation, increased with time after ischemia and was greater than that of sham-operated animals. The present study provides evidence for in vivo ERK phosphorylation in response to NMDA stimulation of BrdU-positive neurons in the adult hippocampus after transient forebrain ischemia.
Sensor integration in task‐level programming and industrial robotic task execution control
Authors: Johansson Rolf , Robertsson Anders , Nilsson Klas , Brogårdh Torgny , Cederberg Per , Olsson Magnus , Olsson Tomas , Bolmsjö Gunnar
Published: April 2004

Presents an approach to improved performance and flexibility in industrial robotics by means of sensor integration and feedback control in task‐level programming and task execution. Also presents feasibility studies in support of the ideas. Discusses some solutions to the problem using six degrees of freedom force control together with the ABB S4CPlus system as an illustrative example. Consider various problems in the design of an open sensor interface for industrial robotics and discusses possible solutions. Finally, presents experimental results from industrial force controlled grinding.
Control in collaborative research and technology development
Authors: Hoecht Andreas
Published: April 2004

It is widely accepted that companies operating in research‐intensive industries need to pursue an “outward‐looking”, collaborative research and technology development strategy. Research collaboration, however, always carries risks, in particular, the risk of sensitive information leakage, be it as a result of purposeful betrayal by collaborators or accidental disclosure. It has been shown that traditional legal and bureaucratic control mechanisms are not able to deal with this problem adequately and that the more “outward‐looking” the research strategy that a company follows, the more it has to rely on social control mechanisms such as reputational concerns of key researchers and the incremental development of higher levels of trust among individuals. This paper analyses the relationship between management control and social control in collaborative research and development in more detail and introduces the results of a small‐scale interview‐based study of the trust‐building and control processes in fine fragrance research.
The depowerment of European middle managers
Authors: Holden Len , Roberts Ian
Published: April 2004

This paper is based on the research of middle managers in three countries (The Netherlands, Sweden, and the UK) in public and private sector organisations. The findings indicate that increasing pressures on managers to perform within a surge of management initiatives and policy moves to make organisations more profitable (in the private sector) and more “efficient” and accountable (in the public sector) invariably lead to contradictions in their performance and perceived roles. In the context of the oxymoron that “they are to do more with less”, this will lead to increased stresses and strains on those performing this pivotal operational role. Terminologically, middle managers are becoming increasingly “depowered”.
How well are corporate ethics codes and policies applied in the trenches?
Authors: von der Embse Thomas J. , Desai Mayur S. , Desai Seema
Published: April 2004

Assesses the extent to which organizational ethics codes, credos and policies are implemented by managers and supervisors in their work. Further identifies and assesses the principal factors that determined the level of consonance between stated ethical policies and values, and their actual practice. Supports and extends previous observations that simply having ethical codes and policies does not guarantee ethical practices throughout the organization. To become a genuinely ethical organization – an important success factor in today's environment – a comprehensive approach and investment in ethical safeguards is needed and should be regarded as a dimension of decision making alongside quality standards, performance, profitability and other strategic considerations.
Use of performance measurement in V2C activity
Authors: Jungman Hannu , Okkonen Jussi , Rasila Tommi , Seppä Marko
Published: April 2004

The sizes, and thereby minimum investments, of venture capital funds grew phenomenally during 1995‐2000. Simultaneously, business started to transform from capital to knowledge intensive and a new gap emerged between venture and capital. A diverse group of actors referred to herein as Venture‐to‐Capital or V2C players help entrepreneurs gross this gap. While incubators, business angels, and various other types of V2C players serve an important role in the emerging knowledge economy, research on their operation has been scarce. The objective of this exploratory study is to define the usability of performance measurement (PM) in the V2C context. Also in the V2C context, PM should be carried out by using a balanced set of measures from several perspectives. Herein, V2C operating models are examined, and critical success‐factors searched‐for, from the perspectives of both entrepreneur and venture capitalist. We suggest nine success factors, several underlying measures, and directions for further research.
The effect of bloodless pump prime on cerebral oxygenation in paediatric patients
Authors: Han S. H. , Kim C. S. , Kim S. D. , Bahk J. H. , Park Y. S.
Published: April 2004

Background:  In paediatric patients, crystalloid prime for cardiopulmonary bypass (CPB) causes further haemodilution in comparison with blood‐containing prime. Thus it may affect the cerebral oxygen supply/demand balance. The purpose of the study was to compare the effect of bloodless pump prime with that of blood‐containing prime on cerebral oxygenation in children.

Methods:  Thirty‐six paediatric patients scheduled for elective repair of atrial or ventricular septal defect were enrolled. In Group C (n = 18), the CPB circuit was primed only with crystalloid. In Group B (n = 18), red blood cells were added to achieve a haematocrit (Hct) of 20% during CPB. The regional cerebral oxygen saturation (rSO2) value measured by near‐infrared spectroscopy was compared between the two groups.

Results:  In both groups, rSO2 decreased below baseline at the start of CPB and during rewarming (P < 0.001, for both groups during each period). At the start of CPB, haemodilution was greater in Group C than in Group B (Hct 16.1 ± 0.7% vs. 20.7 ± 0.5%; P < 0.01), and there was a greater reduction in rSO2 in Group C (49.0 ± 5.4% vs. 59.2 ± 7.0%; P < 0.01). During rewarming, rSO2 was significantly lower in Group C than in Group B (57.8 ± 5.3% vs. 62.8 ± 6.2%; P < 0.01).

Conclusions:  In paediatric patients, the haemodilution associated with crystalloid priming causes a greater reduction in rSO2 than with blood‐containing prime at the starting period of CPB and the rewarming period.
Effects of volatile anesthetics on cardiac ion channels
Authors: Hüneke R. , Faßl J. , Rossaint R. , Lückhoff A.
Published: April 2004

The focus of the present review is on how interference with various ion channels in the heart may be the molecular basis for cardiac side‐effects of gaseous anesthetics. Electrophysiological studies in isolated animal and human cardiomyocytes have identified the L‐type Ca2+ channel as a prominent target of anesthetics. Since this ion channel is of fundamental importance for the plateau phase of the cardiac action potential as well as for Ca2+‐mediated electromechanical coupling, its inhibition may facilitate arrhythmias by shortening the refractory period and may decrease the contractile force. Effective inhibition of this ion channel has been shown for clinically used concentrations of halothane and, to a lesser extent, of isoflurane and sevoflurane, whereas xenon was without effect. Anesthetics furthermore inhibit several types of voltage‐gated K+ channels. Thereby, they may disturb the repolarization and bear a considerable risk for the induction of ventricular tachycardia in predisposed patients. In future, an advanced understanding of cardiac side‐effects of anesthetics will derive from more detailed analyses of how and which channels are affected as well as from a better comprehension of how altered channel function influences heart function.
Competing Conceptions of the First Ladyship: Public Responses to Betty Ford's 60 Minutes Interview
Authors: BORRELLI MARYANNE
Published: April 2004

Has the debate about women's roles in U.S. society allowed first ladies greater latitude in choosing the role(s) they will perform? To answer this question, two points on the spectrum of possible first lady roles–“first political wife” and “wife”–were identified. Public correspondence responding to Betty Ford's 60 Minutes interview was then studied. Ford's critics and supporters each articulated coherent ideologies of gender and presidential power, which were congruent with the theoretical constructs of first political wife and wife. In this instance, the role of first political wife mobilized more critics than supporters and influenced campaign strategies throughout the second half of the Ford administration.
The White House Office of Presidential Personnel
Authors: PATTERSON BRADLEY H. , PFIFFNER JAMES P.
Published: April 2004

One of the greatest challenges of a new presidential administration is recruiting and bringing on board the political appointees who will help the new president lead the executive branch. The people who carry out this task for the president work in the Office of Presidential Personnel (OPP). This article presents an overview of the OPP and how it functions during the transition and early months of a new administration. It first sets out the scope of the job by specifying the number and types of political appointments for which the OPP is responsible. Next, an account of how the office has developed will be presented along with the predictable challenges from pressures for appointments from the Hill, the campaign, and cabinet secretaries. Finally, obligations of the OPP after initial recruitment has been accomplished will be examined.
Studying the Polarized Presidency
Authors: Cameron Charles M.
Published: April 2004

For reasons that political scientists do not fully understand, American political elites are now more ideologically polarized than they have been since the end of World War I. This polarization–in combination with the rise of divided party government–has sweeping implications for the presidency. No aspect of executive‐legislative relations is untouched. But also deeply affected are relations with the media, with thejudiciary, with the bureaucracy, and even the organization of the president's own staff. Presidential scholars are just beginning to grasp these changes. We face an enormous challenge but also a remarkable opportunity. The polarized presidency makes us confront a broader range of the institution's possibilities–and those of American democracy.
Presidential Power and the Research Agenda
Authors: Neustadt Richard E.
Published: April 2004

Presidential Power (1990 edition) contains a pkthora of propositions which ought to be tested against the best evidence that archives in the burgeoning array of presidential libraries provide. More importantly, those also are sources for testing hypotheses in contemporary theories. Theoreticians and historically minded researchers ought to get together and divide up the work. There's lots to do. Incidentally, they might agree on terms of art in presidential studies.
The Polls: Policy‐Specific Presidential Approval, Part 2
Authors: Cohen Jeffrey E.
Published: April 2004

Extant research suggests the primacy of economics over foreign policy in determining public evaluations of the president despite the higher degree of presidential responsibility for foreign, as opposed to economic, policy. Lack of good data on foreign policy attitudes has limited the incorporation of that aspect of public opinion in the study of presidential approval. In this article, I utilize both foreign and economic policy monthly approval times series that span the two terms of the Clinton administration to study the comparative impact of foreign and economic policy thinking on public approval. Results find, first, that the specific approval series granger cause general presidential approval. Second, economic and foreign policy approval seems to have similar impacts on general presidential approval. Implications for understanding public opinion toward the president and directions for future research are discussed.
Sevoflurane depolarizes pre‐synaptic mitochondria in the central nervous system
Authors: Moe M. C. , Bains R. , Vinje M. L. , Larsen G. A. , Kampenhaug E. B. , Berg‐Johnsen J.
Published: April 2004

Background:  Volatile anaesthetics protect the heart from ischaemic injury by activating mitochondrial signalling pathways. The aim of this study was to test whether sevoflurane, which is increasingly used in neuroanaesthesia, affects mitochondrial function in the central nervous system by altering the mitochondrial membrane potential (ΔΨm).

Methods:  In order to correlate free cytosolic Ca2+ ([Ca2+]i) and ΔΨm, rat neural presynaptic terminals (synaptosomes) were loaded with the fluorescent probes fura‐2 and JC‐1. During sevoflurane exposure, 4‐aminopyridine (4‐AP) 500 µM to induce pre‐synaptic membrane depolarization or carbonylcyanide‐p‐(trifluoromethoxy)‐phenylhydrazone (FCCP) 1 µM to induce maximum mitochondrial depolarization was added. In order to block mitochondrial ATP‐regulated K+‐channels (mitoKATP), the antagonist 5‐hydroxydecanoate (5‐HD) 500 µM was added.

Results:  In Ca2+‐containing medium, both sevoflurane 1 and 2 MAC gradually decreased the normalized JC‐1 ratio from 0.96 ± 0.01 in control to 0.92 ± 0.01 and 0.89 ± 0.01, representing a depolarization of ΔΨm (n = 9, P < 0.05). Sevoflurane 2 MAC increased [Ca2+]i. In Ca2+‐depleted medium, sevoflurane 1 and 2 MAC depolarized ΔΨm, while [Ca2+]i remained unaltered. Sevoflurane 2 MAC attenuated the 4‐AP‐induced depolarization of ΔΨm. When mitoKATP was blocked, the sevoflurane‐induced depolarization of ΔΨm was attenuated, but not blocked. The depolarizing effect of sevoflurane on ΔΨm compared with FCCP was calculated to 13.2 ± 1.3% in Ca2+‐containing and 15.1 ± 1.2% in Ca2+‐depleted medium (n = 7).

Conclusions:  Sevoflurane depolarizes ΔΨm in rat synaptosomes, and the effect is not dependent on Ca2+‐influx to the cytosol. Opening of mitoKATP is partly responsible for the depolarizing effect of sevoflurane.
Variation and Repeatability of Female Choice in a Chorusing Katydid, Ephippiger ephippiger: an Experimental Exploration of the Precedence Effect
Authors: Greenfield Michael D. , Siegfreid Eric , Snedden W. Andrew
Published: April 2004

Female choice in various species of acoustic insects and anurans entails a psychoacoustic preference for male calls that lead their neighbors by a brief time interval. This discrimination, which can be termed a precedence effect, may select for various mechanisms with which males adjust call rhythm and thus reduce their incidence of ineffective following calls. At a collective level, alternating and synchronous choruses may emerge from these call timing mechanisms. Using playback experiments, we characterized the precedence effect in females of the katydid Ephippiger ephippiger, an alternating choruser in which males use a rhythm adjustment mechanism that prevents calling during brief intervals following their neighbors’ calls. E. ephippiger females oriented toward leading male calls in >75% of trials when relatively young (<40 d old) and when playbacks were timed so that following calls began within 100–250 ms of the leading ones. However, this preference declined to below 60% as females aged and the interval separating leading and following call onsets increased. The strength of this precedence effect varied greatly between females, but within broad age classes the effect in a given female was statistically repeatable. Such repeatability indicates the possibility that additive genetic variance could be a significant component of variation in the precedence effect. We discuss the implications of our findings and inference on genetic variance for evolution of the precedence effect and for chorusing.