bluuebunny/crossref_metadata_2025 huggingface dataset:
Folate Transport by Prawn Hepatopancreas Brush-Border Membrane Vesicles
Authors: Blaya J. A. , Muriana F. J. G. , Ruiz-Gutierrez V. , Vazquez C. M. , Bolufer J.
Published: March 2003

The transport system of folic acid (Pte-Glu) by brush-border membrane vesicles (BBMV) isolated from prawn (Penaeus japonicm) hepatopancreas, was studied by measuring the uptake of Pte-Glu. This uptake was found to have two components, intravesicular transport and membrane binding. Membrane binding was not affected by the presence of a transmembrane pH-gradient at a short incubation period. However, a transmembrane pH-gradient increased membrane binding at 60 min. The transport of Pte-Glu appeared to be carrier-mediated, was stimulated by an inwardly proton gradient (pH 5.5 outside, 7.4 inside) and was unaffected by a sodium-gradient. The relationship between pH gradient-driven Pte-Glu uptake and medium Pte-Glu concentration followed saturating Michaelis–Menten kinetics. Eadie–Hofstee representation of the pH gradient-driven Pte-Glu uptake indicated a single transport system with a Km of 0.37 μM and Vmax of 1.06 pmol/mg protein/15 s. These findings indicate that BBMV isolated from prawn hepatopancreas possesses a Pte-Glu transport system similar to that described in mammalian intestine.
Adjustment Problems and Emerging Personality Characteristics from Early to Late Adolescence
Authors: Ge Xiaojia , Conger Rand D.
Published: March 2003

This 6‐year longitudinal study extended earlier findings of contextual influences on adolescent adjustment problems by examining relationships between adolescent emotional and behavioral problems and late adolescent personality among more than 400 youths who were followed from 7th grade to the last year of high school. Results suggest that psychological distress and behavioral problems experienced during the adolescent years (7th–10th grades) are significantly related to personality structure during the final year of high school (12th grade). Psychological distress in adolescence was primarily related to the Multidimensional Personality Questionnaire (MPQ) superfactors of negative and positive emotionality, whereas delinquency and substance use problems were primarily related to the MPQ superfactor of constraint. These relationships remained significant even when personality characteristics in 9th grade were taken into account. That is, emotional and behavioral problems predicted change in personality traits during the adolescent years. Moreover, both initial level and change in distress and problem behaviors were predictive of late adolescent or early adult personality. This finding suggests that personality formation is a dynamic process, dependent on the growth or decline, as well as the magnitude of earlier developmental problems. Because earlier research has shown that these developmental problems are affected by both distal and proximal environmental contexts as well as by the formative nature of adolescence, intervention efforts aimed at the reduction of maladjustment and the enhancement of healthy personality development should target early adolescent social contexts. Other theoretical implications of the findings also are discussed.
The Program Environment Scale: Assessing Client Perceptions of Community‐Based Programs for the Severely Mentally Ill
Authors: Burt Martha R. , Duke Amy-Ellen , Hargreaves William A.
Published: March 2003

The Program Environment Scale (PES) was developed for use with clients of community‐based programs for the severely mentally ill. It is intended to fill the gap in available tools for assessing clients' perceptions of program functioning as it affects their “quality of life” in a program. Formal pretests were conducted with 121 clients at 12 randomly selected programs near Washington, DC. The final field test used a revised form (29 domains; 129 items) with 221 clients in 22 programs selected randomly throughout the U.S., including Clubhouse, day treatment, psychosocial rehabilitation, and social club programs. Twenty‐three subscales met at least five of eight psychometric criteria for internal consistency and discriminant validity. A 24th subscale was retained because of its substantive importance. Successful subscales cover program atmosphere and interactions (program cares about me, energy level, friendliness, openness, staff‐client and client‐client respect, reasonable rules, availability of positive physical contact, protection from bad touch, staff investment in their jobs, and confidentiality), client empowerment/staff‐client equality (program and treatment empowerment, egalitarian space use), and service components (support for paid work, work importance, emergency access, family activities, housing, public benefits, community activities, medications, substance abuse, and continuity). Subscale validity is indicated by associations of specific service offerings with scores on scales measuring client perceptions of those services, and by an ability to differentiate among program models (i.e., Clubhouses, day treatment programs, and psychosocial rehabilitation programs look different from each other). Subscale scores were not influenced by client characteristics (gender, race, age, diagnosis, number of hospitalizations, length of time in program). The final scale has 97 items and takes about 25 minutes to complete. The PES succeeds in measuring different aspects of programs as clients perceive them. In the programs we visited, directors felt the PES covers the important things they want to know about how clients perceive their program. The PES should become a useful tool both for researchers interested in how client responses to programs may influence their therapeutic outcomes, and for practitioners interested in improving their clients' program experiences and/or increasing convergence of staff and client views of their program.
Adolescent Development and Juvenile Justice
Authors: Reppucci N. Dickon
Published: March 2003

The central question examined in this address is, “Do children's crimes make them adults?” I begin by focusing on the concept and history of adolescence in our society, I then examine the development and philosophy of the juvenile justice system. Adolescent development and juvenile justice are brought together around the concepts of maturity, judgment, and competence, followed by a brief introduction to some current research that we are engaged in regarding the issues of adjudicatory and culpability competence. I conclude with suggested directions for future work.
The Identification of Early Risk Factors for Severe Emotional Disturbances and Emotional Handicaps: An Epidemiological Approach
Authors: Mason Craig A. , Chapman Derek A. , Scott Keith G.
Published: March 2003

Epidemiological methodology is used to examine the relationship between early childhood risk factors and future identification as having a Severe Emotional Disturbance or as having an Emotional Handicap (SED/EH) at age 13. Data were obtained from 1979/1980 Florida birth records that were electronically linked with 1992/1993 Florida school records. An epidemiological perspective was chosen due to its ability to model both individual and community‐level risk. In regards to increasing an individual's risk of SED/EH, two factors, gender (being male) and low maternal education (mother not completing high school at the time of the child's birth), were found to have particularly strong effects. When examining effects of these risk factors upon overall rates of SED/EH in the community, maternal education and marital status (being unmarried at the time of the child's birth) were associated with a large proportion of the cases. Health/biological markers were moderately associated with SED/EH on the individual level, but were related to a relatively small percentage of cases in the population. In addition, effects varied based upon ethnic/cultural heritage. Researchers are encouraged to consider using an epidemiological perspective and its potential utility in the field of community psychology and public policy is discussed.
“Nothing About Me, Without Me”: Participatory Action Research with Self‐Help/Mutual Aid Organizations for Psychiatric Consumer/Survivors
Authors: Nelson Geoffrey , Ochocka Joanna , Griffin Kara , Lord John
Published: March 2003

Participatory action research with self‐help/mutual aid organizations for psychiatric consumer/survivors is reviewed. We begin by tracing the origins of and defining both participatory action research and self‐help/mutual aid. In so doing, the degree of correspondence between the assumptions/values of participatory action research and those of self‐help/mutual aid for psychiatric consumer/survivors is examined. We argue that participatory action research and self‐help/mutual aid share four values in common: (a) empowerment, (b) supportive relationships, (c) social change, and (d) learning as an ongoing process. Next, selected examples of participatory action research with psychiatric consumer/survivor‐controlled self‐help/mutual aid organizations which illustrate these shared values are provided. We conclude with recommendations of how the key values can be promoted in both the methodological and substantive aspects of future participatory action research with self‐help/mutual aid organizations for psychiatric consumer/survivors.
Potentiation of liver X receptor transcriptional activity by peroxisome-proliferator-activated receptor gamma co-activator 1alpha
Authors: OBERKOFLER Hannes , SCHRAML Elisabeth , KREMPLER Franz , PATSCH Wolfgang
Published: March 2003

Peroxisome-proliferator-activated receptor (PPAR) γ co-activator 1α (PGC-1α/PPARGC1) plays an important role in energy metabolism by co-ordinating transcriptional programmes of mitochondrial biogenesis, adaptive thermogenesis and fatty acid β-oxidation. PGC-1α has also been identified to play a role in the intermediary metabolism by co-activating key transcription factors of hepatic gluconeogenesis and glucose uptake in muscles. In the present study, we show that PGC-1α serves as a co-activator for the liver X receptor (LXR) α, known to contribute to the regulation of cellular cholesterol homoeostasis. In transient transfection studies, PGC-1α amplified the LXR-mediated autoregulation of the LXRα promoter in a human brown adipocyte line and in 3T3-L1 cells via an LXR response element described previously. LXR-mediated transactivation via a natural LXR response element from the cholesteryl ester transfer-protein gene promoter was also enhanced by PGC-1α in a ligand-dependent manner. Mutational analysis showed that the LXXLL signature motif (L2) of PGC-1α was essential for co-activation of LXR-mediated transcriptional responses. This motif is located in the vicinity of the binding region for a putative repressor described previously. The repressor sequesters PGC-1α from PPARα and the glucocorticoid receptor, and this repressor did not interfere with PGC-1α-mediated co-activation of LXR-dependent gene transcription. Moreover, inhibition of p38 mitogen-activated protein kinase signalling, shown to abolish the co-activation of PPARα by PGC-1α, had only a moderate inhibitory effect on the co-activation of LXR. These results identify PGC-1α as a bona fide LXR co-activator and implicate distinct interfaces of PGC-1α and/or additional cofactors in the modulation of LXR and PPARα transcriptional activities.
Comprehensive mapping of HLA-A*0201-restricted CD8 T-cell epitopes on PDC-E2 in primary biliary cirrhosis
Authors: Matsumura Shuji , Kita Hiroto , He Xiao-Song , Ansari Aftab A. , Lian Zhe-Xiong , van de Water Judy , Yamamoto Kazuhide , Tsuji Takao , Coppel Ross L. , Kaplan Marshall , Gershwin Eric M.
Published: March 2003

Growing evidence has implicated the involvement of autoreactive T lymphocytes in the pathogenesis of primary biliary cirrhosis (PBC). We have recently taken advantage of motif prediction analysis of HLA-A*0201 and identified the first major histocompatibility complex (MHC) class I restricted epitope, amino acids 159 to 167 on E2 components of pyruvate dehydrogenase complexes (PDC-E2), the major mitochondrial antigens in PBC. The mechanisms involved in the selection of epitope peptide(s) that comprise the PDC-E2-specific autoreactive cytotoxic T lymphocytes (CTLs) are unknown and likely involve other epitopes on PDC-E2 restricted by MHC class I molecules. To address this issue, a comprehensive mapping of the CTL epitope repertoire on the PDC-E2 molecule that binds HLA-A*0201 was performed to provide further clues regarding the role of CTLs. We used the T2 cell line to screen 79 overlapping 15mer peptides, spanning the entire PDC-E2 molecule. Six of the 79 peptides exhibited significantly higher binding activity to HLA-A*0201 than the other 15mer peptides. Two of these 6 peptides induced CTL lines from patients with PBC. Fine mapping with N-terminus or C-terminus truncated peptides identified 10mer peptide, PDC-E2 amino acids 165 to 174, which is a novel CD8 epitope restricted by HLA-A*0201. In conclusion, using a combination of the 15mer peptide library screening with the T2 binding assay and also the induction of CTL lines with candidate peptides, we have defined a novel HLA-A*0201-restricted epitope PDC-E2 165 to 174 in patients with PBC. These data will become important in the development of altered peptide ligands to modulate disease activity.
Epidemiology of the American Indians’ burden and its likely genetic origins
Authors: Carey Martin C. , Paigen Beverly
Published: March 2003

It was not known until recently whether the endemic of cholesterol gallstones among certain southwestern American Indian tribes was unique among this ethnic group. With use of ultrasonography of the gallbladder and standard diagnostic criteria, gallstones are now found in epidemic proportions in 13 diverse American Indian tribes and communities living in Arizona, Oklahoma, and the Dakotas. We speculate that this predisposition is polygenic involving “thrifty” genes that conferred survival advantages when Paleo-Indians migrated from present-day Siberia to the Americas during the last Great Ice Age approximately 50,000 to 10,000 years ago. A reasonable hypothesis is that functioning of these genes promoted more efficient calorie utilization and storage in the form of adipose tissue. Beneficial results would have been operative during the isolation of Paleo-Indians in the Bering Strait land bridge (Beringia) when thrifty genes would have ensured sufficient fat reserves for survival of prolonged winters, successful pregnancy outcomes, and extended lactation periods. The authors’ conjoint work on genetics of experimental cholesterol cholelithiasis in inbred mice promises help in pinpointing orthologous genetic loci (LITH genes) in the human genome. Moreover, the shared environments and homogeneity of American Indian tribes and communities should facilitate discovery of the ensembles of their common and rarer cholesterol gallstone genes. It is anticipated that knowledge of expression, polymorphisms, and functionality of LITH genes will help resolve the molecular mechanisms of this complex heterogeneous trait and thereby provide targets for novel therapies to prevent cholesterol cholelithiasis worldwide.
Lith genes control mucin accumulation, cholesterol crystallization, and gallstone formation in A/J and AKR/J inbred mice
Authors: Lammert Frank , Wang David Q.-H. , Wittenburg Henning , Bouchard Guylaine , Hillebrandt Sonja , Taenzler Bärbel , Carey Martin C. , Paigen Beverly
Published: March 2003

We recently identified 2 Lith genes that determine cholesterol gallstone formation in C57L/J inbred mice, which show a gallstone prevalence of ˜80% on feeding 1.0% cholesterol and 0.5% cholic acid. The aim of this study was to explore if the same Lith loci contribute to the variation in gallstone susceptibility in a new experimental cross. After 12 weeks of feeding the lithogenic diet to inbred mice of strains A/J and AKR/J as well as their F1 progeny, we used microscopy of bile to assess mucin accumulation, crystallization pathways, and stone formation. Backcross progeny (n = 225) were phenotyped and genotyped selectively for microsatellite markers spanning the genome. Quantitative trait loci (QTL) affecting gallstone phenotypes were identified by linkage analysis. Both inbred strains showed accumulation of mucin gel and cholesterol supersaturation. However, only strain AKR developed gallstones (prevalence of 20%), whereas strain A showed a stable liquid crystalline state and no stones. QTL analysis identified a gallstone locus on chromosome 17 (Lith3). A second gene locus on chromosome 15 that controls mucin accumulation harbors the mucin gene Glycam1, which was shown to be expressed in gallbladder epithelia by immunohistochemistry. Gallstone and mucin loci colocalized with potential QTLs affecting the formation of cholesterol crystals. In conclusion, QTL analysis identified specific gene loci determining mucin accumulation, cholesterol crystallization, and gallstone formation. Characterization of the pathophysiologic roles of Lith3 and the new biliary mucin gene Glycam1 might provide insights into primary defects of human cholelithiasis and lead to new therapeutic strategies for prestone intervention.
The ecto-nucleoside triphosphate diphosphohydrolase NTPDase2/CD39L1 is expressed in a novel functional compartment within the liver
Authors: Dranoff Jonathan A. , Kruglov Emma A. , Robson Simon C. , Braun Norbert , Zimmermann Herbert , Sévigny Jean
Published: March 2003

Extracellular nucleotides regulate diverse biological functions and are important in the regulation of liver metabolism, hepatic blood flow, and bile secretion. Ecto-nucleoside triphosphate diphosphohydrolases (NTPDases) hydrolyze extracellular nucleotides and are therefore potential regulators of nucleotide-mediated signaling. To examine this, we have contrasted the structural and functional distributions of the 2 characterized membrane-bound NTPDases NTPDase1 and NTPDase2 within the rat liver. Hepatic expression of NTPDase2 was determined and contrasted to NTPDase1 using confocal immunofluorescence, immunoelectron microscopy, reverse-transcription polymerase chain reaction, Northern blot analysis, Western blot analysis, and functional assays. NTPDase2 was expressed in the periportal region surrounding intrahepatic bile ducts, whereas NTPDase1 was found in hepatic arteries, portal veins, and hepatic central veins, consistent with its known vascular distribution. Functional and molecular expression of NTPDase2 was shown in portal fibroblasts near basolateral membranes of bile duct epithelia. In conclusion, NTPDase2 is expressed in a novel cellular compartment surrounding intrahepatic bile ducts, namely portal fibroblasts. This distribution may represent a previously unrecognized mechanism for regulation of nucleotide signaling in bile ducts and other epithelia.
On Ramanujan’s continued fraction for (𝑞²;𝑞³)_{∞}/(𝑞;𝑞³)_{∞}
Authors: Andrews George , Berndt Bruce , Sohn Jaebum , Yee Ae Ja , Zaharescu Alexandru
Published: March 2003

The continued fraction in the title is perhaps the deepest of Ramanujan’s

q
q

-continued fractions. We give a new proof of this continued fraction, more elementary and shorter than the only known proof by Andrews, Berndt, Jacobsen, and Lamphere. On page 45 in his lost notebook, Ramanujan states an asymptotic formula for a continued fraction generalizing that in the title. The second main goal of this paper is to prove this asymptotic formula.
Tame sets, dominating maps, and complex tori
Authors: Buzzard Gregery
Published: March 2003

A discrete subset of

C

n

\mathbb C^n

is said to be tame if there is an automorphism of

C

n

\mathbb C^n

taking the given discrete subset to a subset of a complex line; such tame sets are known to allow interpolation by automorphisms. We give here a fairly general sufficient condition for a discrete set to be tame. In a related direction, we show that for certain discrete sets in

C

n

\mathbb C^n

there is an injective holomorphic map from

C

n

\mathbb C^n

into itself whose image avoids an

ϵ
\epsilon

-neighborhood of the discrete set. Among other things, this is used to show that, given any complex

n
n

-torus and any finite set in this torus, there exist an open set containing the finite set and a locally biholomorphic map from

C

n

\mathbb C^n

into the complement of this open set.
On 𝐿^{𝑝} continuity of singular Fourier integral operators
Authors: Comech Andrew , Cuccagna Scipio
Published: March 2003

We derive

L

p

L^{p}

continuity of Fourier integral operators with one-sided fold singularities. The argument is based on interpolation of (asymptotics of)

L

2

L^{2}

estimates and

H

1

→

L
1

\mathrm {H}^1\to L^1

estimates. We derive the latter estimates elaborating arguments of Seeger, Sogge, and Stein’s 1991 paper. We apply our results to the study of the

L

p

L^{p}

regularity properties of the restrictions of solutions to hyperbolic equations onto timelike hypersurfaces and onto hypersurfaces with characteristic points.
Central Kähler metrics with non-constant central curvature
Authors: Hwang Andrew , Maschler Gideon
Published: March 2003

The central curvature of a Riemannian metric is the determinant of its Ricci endomorphism, while the scalar curvature is its trace. A Kähler metric is called central if the gradient of its central curvature is a holomorphic vector field. Such metrics may be viewed as analogs of the extremal Kähler metrics defined by Calabi. In this work, central metrics of non-constant central curvature are constructed on various ruled surfaces, most notably the first Hirzebruch surface. This is achieved via the momentum construction of Hwang and Singer, a variant of an ansatz employed by Calabi (1979) and by Koiso and Sakane (1986). Non-existence, real-analyticity and positivity properties of central metrics arising in this ansatz are also established.
Central Kähler metrics
Authors: Maschler Gideon
Published: March 2003

The determinant of the Ricci endomorphism of a Kähler metric is called its central curvature, a notion well-defined even in the Riemannian context. This work investigates two types of Kähler metrics in which this curvature potential gives rise to a potential for a gradient holomorphic vector field. These metric types generalize the Kähler-Einstein notion as well as that of Bando and Mabuchi (1986). Whenever possible the central curvature is treated in analogy with the scalar curvature, and the metrics are compared with the extremal Kähler metrics of Calabi. An analog of the Futaki invariant is employed, both invariants belonging to a family described in the language of holomorphic equivariant cohomology. It is shown that one of the metric types realizes the minimum of an

L
2

L^2

functional defined on the space of Kähler metrics in a given Kähler class. For metrics of constant central curvature, results are obtained regarding existence, uniqueness and a partial classification in complex dimension two. Consequently, on a manifold of Fano type, such metrics and Kähler-Einstein metrics can only exist concurrently. An existence result for the case of non-constant central curvature is stated, and proved in a sequel to this work.
Fixed points of commuting holomorphic mappings other than the Wolff point
Authors: Bracci Filippo
Published: March 2003

Let

Δ
\Delta

be the unit disc of

C

\mathbb C

and let

f
,
g
∈

H
o
l

(
Δ
,
Δ
)

f,g \in \mathrm {Hol}(\Delta ,\Delta )

be such that

f
∘
g
=
g
∘
f

f \circ g = g \circ f

. For

A
>
1

A>1

, let
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper F normal i normal x Subscript upper A Baseline left-parenthesis f right-parenthesis colon equals StartSet p element-of partial-differential normal upper Delta bar limit Underscript r right-arrow 1 Endscripts f left-parenthesis r p right-parenthesis equals p comma limit Underscript r right-arrow 1 Endscripts StartAbsoluteValue f prime left-parenthesis r p right-parenthesis EndAbsoluteValue less-than-or-equal-to upper A EndSet">

F
i
x

A

(
f
)
:=
{
p
∈
∂
Δ
∣

lim

r
→
1

f
(
r
p
)
=
p
,

lim

r
→
1

|

f
′

(
r
p
)

|

≤
A
}

\mathrm {Fix}_A (f):=\{p \in \partial \Delta \mid \lim _{r \to 1}f(rp)=p, \lim _{r \to 1}|f’(rp)|\leq A \}

. We study the behavior of

g
g

on

F
i
x

A

(
f
)

\mathrm {Fix}_A (f)

. In particular, we prove that
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="g left-parenthesis normal upper F normal i normal x Subscript upper A Baseline left-parenthesis f right-parenthesis right-parenthesis subset-of-or-equal-to normal upper F normal i normal x Subscript upper A Baseline left-parenthesis f right-parenthesis">

g
(

F
i
x

A

(
f
)
)
⊆

F
i
x

A

(
f
)

g(\mathrm {Fix}_A (f))\subseteq \mathrm {Fix}_A (f)

. As a consequence, besides conditions for

F
i
x

A

(
f
)
∩

F
i
x

A

(
g
)
≠
∅

\mathrm {Fix}_A(f) \cap \mathrm {Fix}_A(g) \neq \emptyset

, we prove a conjecture of C. Cowen in case

f
f

and

g
g

are univalent mappings.
On a measure in Wiener space and applications
Authors: Ryu K. , Im M.
Published: March 2003

In this article, we consider a measure in Wiener space, induced by the sum of measures associated with an uncountable set of positive real numbers, and investigate the basic properties of this measure. We apply this measure to the various theories related to Wiener space. In particular, we can obtain a partial answer to Johnson and Skoug’s open problems, raised in their 1979 paper. Moreover, we can improve and clarify some theories related to Wiener space.
Non-crossing cumulants of type B
Authors: Biane Philippe , Goodman Frederick , Nica Alexandru
Published: March 2003

We establish connections between the lattices of non-crossing partitions of type B introduced by V. Reiner, and the framework of the free probability theory of D. Voiculescu. Lattices of non-crossing partitions (of type A, up to now) have played an important role in the combinatorics of free probability, primarily via the non-crossing cumulants of R. Speicher. Here we introduce the concept of non-crossing cumulant of type B; the inspiration for its definition is found by looking at an operation of “restricted convolution of multiplicative functions”, studied in parallel for functions on symmetric groups (in type A) and on hyperoctahedral groups (in type B). The non-crossing cumulants of type B live in an appropriate framework of “non-commutative probability space of type B”, and are closely related to a type B analogue for the R-transform of Voiculescu (which is the free probabilistic counterpart of the Fourier transform). By starting from a condition of “vanishing of mixed cumulants of type B”, we obtain an analogue of type B for the concept of free independence for random variables in a non-commutative probability space.
Stationary sets for the wave equation in crystallographic domains
Authors: Agranovsky Mark , Quinto Eric
Published: March 2003

Let

W
W

be a crystallographic group in

R

n

\mathbb R^n

generated by reflections and let

Ω
\Omega

be the fundamental domain of

W
.

W.

We characterize stationary sets for the wave equation in

Ω
\Omega

when the initial data is supported in the interior of

Ω
.

\Omega .

The stationary sets are the sets of time-invariant zeros of nontrivial solutions that are identically zero at

t
=
0

t=0

. We show that, for these initial data, the

(
n
−
1
)

(n-1)

-dimensional part of the stationary sets consists of hyperplanes that are mirrors of a crystallographic group

W
~

\tilde W

,

W
>

W
~

.

W>\tilde W.

This part comes from a corresponding odd symmetry of the initial data. In physical language, the result is that if the initial source is localized strictly inside of the crystalline

Ω
\Omega

, then unmovable interference hypersurfaces can only be faces of a crystalline substructure of the original one.
Regularity of weak solutions to the Monge–Ampère equation
Authors: Gutiérrez Cristian , Hartenstine David
Published: March 2003

We study the properties of generalized solutions to the Monge–Ampère equation

det

D
2

u
=
ν

\det D^2 u = \nu

, where the Borel measure

ν
\nu

satisfies a condition, introduced by Jerison, that is weaker than the doubling property. When

ν
=
f

d
x

\nu = f \, dx

, this condition, which we call

D

ϵ

D_{\epsilon }

, admits the possibility of

f
f

vanishing or becoming infinite. Our analysis extends the regularity theory (due to Caffarelli) available when

0
>
λ
≤
f
≤
Λ
>
∞

0 > \lambda \leq f \leq \Lambda > \infty

, which implies that

ν
=
f

d
x

\nu = f \, dx

is doubling. The main difference between the

D

ϵ

D_{\epsilon }

case and the case when

f
f

is bounded between two positive constants is the need to use a variant of the Aleksandrov maximum principle (due to Jerison) and some tools from convex geometry, in particular the Hausdorff metric.
Contractive projections and operator spaces
Authors: Neal Matthew , Russo Bernard
Published: March 2003

Parallel to the study of finite-dimensional Banach spaces, there is a growing interest in the corresponding local theory of operator spaces. We define a family of Hilbertian operator spaces

H
n
k

H_n^k

,

1
≤
k
≤
n

1\le k\le n

, generalizing the row and column Hilbert spaces

R
n

R_n

and

C
n

C_n

, and we show that an atomic subspace

X
⊂
B
(
H
)

X\subset B(H)

that is the range of a contractive projection on

B
(
H
)

B(H)

is isometrically completely contractive to an

ℓ
∞

\ell ^\infty

-sum of the

H
n
k

H_n^k

and Cartan factors of types 1 to 4. In particular, for finite-dimensional

X
X

, this answers a question posed by Oikhberg and Rosenthal. Explicit in the proof is a classification up to complete isometry of atomic w

∗

^*

-closed

J

W
∗

JW^*

-triples without an infinite-dimensional rank 1 w

∗

^*

-closed ideal.
A positive radial product formula for the Dunkl kernel
Authors: Rösler Margit
Published: March 2003

It is an open conjecture that generalized Bessel functions associated with root systems have a positive product formula for nonnegative multiplicity parameters of the associated Dunkl operators. In this paper, a partial result towards this conjecture is proven, namely a positive radial product formula for the non-symmetric counterpart of the generalized Bessel function, the Dunkl kernel. Radial here means that one of the factors in the product formula is replaced by its mean over a sphere. The key to this product formula is a positivity result for the Dunkl-type spherical mean operator. It can also be interpreted in the sense that the Dunkl-type generalized translation of radial functions is positivity-preserving. As an application, we construct Dunkl-type homogeneous Markov processes associated with radial probability distributions.
On Ginzburg’s bivariant Chern classes
Authors: Yokura Shoji
Published: March 2003

The convolution product is an important tool in geometric representation theory. Ginzburg constructed the “bivariant" Chern class operation from a certain convolution algebra of Lagrangian cycles to the convolution algebra of Borel-Moore homology. In this paper we prove a “constructible function version" of one of Ginzburg’s results; motivated by its proof, we introduce another bivariant algebraic homology theorysAHs\mathbb {AH}on smooth morphisms of nonsingular varieties and show that the Ginzburg bivariant Chern class is the unique Grothendieck transformation from the Fulton-MacPherson bivariant theory of constructible functions to this new bivariant algebraic homology theory, modulo a reasonable conjecture. Furthermore, taking a hint from this conjecture, we introduce another bivariant theoryGF\mathbb {GF}of constructible functions, and we show that the Ginzburg bivariant Chern class is the unique Grothendieck transformation fromGF\mathbb {GF}tosAHs\mathbb {AH}satisfying the “normalization condition" and that it becomes the Chern-Schwartz-MacPherson class when restricted to the morphisms to a point.
Four-weight spin models and Jones pairs
Authors: Chan Ada , Godsil Chris , Munemasa Akihiro
Published: March 2003

We introduce and discuss Jones pairs. These provide a generalization and a new approach to the four-weight spin models of Bannai and Bannai. We show that each four-weight spin model determines a “dual” pair of association schemes.
An elementary invariant problem and general linear group cohomology restricted to the diagonal subgroup
Authors: Anton Marian
Published: March 2003

Conjecturally, for

p
p

an odd prime and

R
R

a certain ring of

p
p

-integers, the stable general linear group

G
L
(
R
)

GL(R)

and the étale model for its classifying space have isomorphic mod

p
p

cohomology rings. In particular, these two cohomology rings should have the same image with respect to the restriction map to the diagonal subgroup. We show that a strong unstable version of this last property holds for any rank if

p
p

is regular and certain homology classes for

S

L
2

(
R
)

SL_2(R)

vanish. We check that this criterion is satisfied for

p
=
3

p=3

as evidence for the conjecture.
A 𝐶¹ function for which the 𝜔-limit points are not contained in the closure of the periodic points
Authors: D’Aniello Emma , Steele T.
Published: March 2003

We develop a

C
1

C^1

function

f
:
[
−

1
6

,
1
]
→
[
−

1
6

,
1
]

f: [- \frac {1}{6}, 1] \rightarrow [- \frac {1}{6}, 1]

for which

Λ
(
f
)
≠

P
(
f
)

¯

\Lambda (f) \not = \overline {P(f)}

. This answers a query from Block and Coppel (1992).
Construction of 𝑡-structures and equivalences of derived categories
Authors: Tarrío Leovigildo Alonso , López Ana Jeremías , Salorio María José
Published: March 2003

We associate a

t
t

-structure to a family of objects in

D

(

A

)

\boldsymbol {\mathsf {D}}(\mathcal {A})

, the derived category of a Grothendieck category

A

\mathcal {A}

. Using general results on

t
t

-structures, we give a new proof of Rickard’s theorem on equivalence of bounded derived categories of modules. Also, we extend this result to bounded derived categories of quasi-coherent sheaves on separated divisorial schemes obtaining, in particular, Beĭlinson’s equivalences.
Finiteness theorems for positive definite 𝑛-regular quadratic forms
Authors: Chan Wai Kiu , Oh Byeong-Kweon
Published: March 2003

An integral quadratic form

f
f

of

m
m

variables is said to be

n
n

-regular if

f
f

globally represents all quadratic forms of

n
n

variables that are represented by the genus of

f
f

. For any

n
≥
2

n \geq 2

, it is shown that up to equivalence, there are only finitely many primitive positive definite integral quadratic forms of

n
+
3

n + 3

variables that are

n
n

-regular. We also investigate similar finiteness results for almost

n
n

-regular and spinor

n
n

-regular quadratic forms. It is shown that for any

n
≥
2

n \geq 2

, there are only finitely many equivalence classes of primitive positive definite spinor or almost

n
n

-regular quadratic forms of

n
+
2

n + 2

variables. These generalize the finiteness result for 2-regular quaternary quadratic forms proved by Earnest (1994).
Induction theorems of surgery obstruction groups
Authors: Morimoto Masaharu
Published: March 2003

Let

G
G

be a finite group. It is well known that a Mackey functor

{
H
↦
M
(
H
)
}

\{ H \mapsto M(H) \}

is a module over the Burnside ring functor

{
H
↦
Ω
(
H
)
}

\{ H \mapsto \Omega (H) \}

, where

H
H

ranges over the set of all subgroups of

G
G

. For a fixed homomorphism

w
:
G
→
{
−
1
,
1
}

w : G \to \{ -1, 1 \}

, the Wall group functor

{
H
↦

L
n
h

(

Z

[
H
]
,
w

|

H

)
}

\{ H \mapsto L_n^h ({\mathbb Z}[H], w|_H) \}

is not a Mackey functor if

w
w

is nontrivial. In this paper, we show that the Wall group functor is a module over the Burnside ring functor as well as over the Grothendieck-Witt ring functor

{
H
↦

G
W

0

(

Z

,
H
)
}

\{ H \mapsto {\mathrm {GW}}_0 ({\mathbb Z}, H) \}

. In fact, we prove a more general result, that the functor assigning the equivariant surgery obstruction group on manifolds with middle-dimensional singular sets to each subgroup of

G
G

is a module over the Burnside ring functor as well as over the special Grothendieck-Witt ring functor. As an application, we obtain a computable property of the functor described with an element in the Burnside ring.
Multivariable cochain operations and little 𝑛-cubes
Authors: McClure James , Smith Jeffrey
Published: March 2003

In this paper we construct a small

E
∞

E_\infty

chain operad

S

\mathcal {S}

which acts naturally on the normalized cochains

S
∗

X

S^*X

of a topological space. We also construct, for each

n
n

, a suboperad

S

n

\mathcal {S}_n

which is quasi-isomorphic to the normalized singular chains of the little

n
n

-cubes operad. The case

n
=
2

n=2

leads to a substantial simplification of our earlier proof of Deligne’s Hochschild cohomology conjecture.
𝐿^{𝑝} improving bounds for averages along curves
Authors: Tao Terence , Wright James
Published: March 2003

We establish local

(

L
p

,

L
q

)

(L^p,L^q)

mapping properties for averages on curves. The exponents are sharp except for endpoints.
Sharp global well-posedness for KdV and modified KdV on ℝ and 𝕋
Authors: Colliander J. , Keel M. , Staffilani G. , Takaoka H. , Tao T.
Published: March 2003

The initial value problems for the Korteweg-de Vries (KdV) and modified KdV (mKdV) equations under periodic and decaying boundary conditions are considered. These initial value problems are shown to be globally well-posed in allL2L^2-based Sobolev spacesHsH^swhere local well-posedness is presently known, apart from theH14(R)H^{\frac {1}{4}} (\mathbb {R} )endpoint for mKdV and theH−34H^{-\frac {3}{4}}endpoint for KdV. The result for KdV relies on a new method for constructing almost conserved quantities using multilinear harmonic analysis and the available local-in-time theory. Miura’s transformation is used to show that global well-posedness of modified KdV is implied by global well-posedness of the standard KdV equation.
Multidimensional transonic shocks and free boundary problems for nonlinear equations of mixed type
Authors: Chen Gui-Qiang , Feldman Mikhail
Published: March 2003

We establish the existence and stability of multidimensional transonic shocks for the Euler equations for steady potential compressible fluids. The Euler equations, consisting of the conservation law of mass and the Bernoulli law for the velocity, can be written as a second-order, nonlinear equation of mixed elliptic-hyperbolic type for the velocity potential. The transonic shock problem can be formulated into the following free boundary problem: The free boundary is the location of the transonic shock which divides the two regions of smooth flow, and the equation is hyperbolic in the upstream region where the smooth perturbed flow is supersonic. We develop a nonlinear approach to deal with such a free boundary problem in order to solve the transonic shock problem. Our results indicate that there exists a unique solution of the free boundary problem such that the equation is always elliptic in the downstream region and the free boundary is smooth, provided that the hyperbolic phase is close to a uniform flow. We prove that the free boundary is stable under the steady perturbation of the hyperbolic phase. We also establish the existence and stability of multidimensional transonic shocks near spherical or circular transonic shocks.
Resultants and Chow forms via exterior syzygies
Authors: Eisenbud David , Schreyer Frank-Olaf , Weyman Jerzy
Published: March 2003

Given a sheaf on a projective space

P

n

{\mathbf P}^n

, we define a sequence of canonical and effectively computable Chow complexes on the Grassmannians of planes in

P

n

{\mathbf P}^n

, generalizing the well-known Beilinson monad on

P

n

{\mathbf P}^n

. If the sheaf has dimension

k
k

, then the Chow form of the associated

k
k

-cycle is the determinant of the Chow complex on the Grassmannian of planes of codimension

k
+
1

k+1

. Using the theory of vector bundles and the canonical nature of the complexes, we are able to give explicit determinantal and Pfaffian formulas for resultants in some cases where no polynomial formulas were known. For example, the Horrocks–Mumford bundle gives rise to a polynomial formula for the resultant of five homogeneous forms of degree eight in five variables.
The Weil-Petersson metric and volumes of 3-dimensional hyperbolic convex cores
Authors: Brock Jeffrey
Published: March 2003

We present a coarse interpretation of the Weil-Petersson distance

d

W
P

(
X
,
Y
)

d_{\mathrm {WP}}(X,Y)

between two finite area hyperbolic Riemann surfaces

X
X

and

Y
Y

using a graph of pants decompositions introduced by Hatcher and Thurston. The combinatorics of the pants graph reveal a connection between Riemann surfaces and hyperbolic 3-manifolds conjectured by Thurston: the volume of the convex core of the quasi-Fuchsian manifold

Q
(
X
,
Y
)

Q(X,Y)

with

X
X

and

Y
Y

in its conformal boundary is comparable to the Weil-Petersson distance

d

W
P

(
X
,
Y
)

d_{\mathrm {WP}}(X,Y)

. In applications, we relate the Weil-Petersson distance to the Hausdorff dimension of the limit set and the lowest eigenvalue of the Laplacian for

Q
(
X
,
Y
)

Q(X,Y)

, and give a new finiteness criterion for geometric limits.
Correlation function of Schur process with application to local geometry of a random 3-dimensional Young diagram
Authors: Okounkov Andrei , Reshetikhin Nikolai
Published: March 2003

The Schur process is a time-dependent analog of the Schur measure on partitions studied by A. Okounkov inInfinite wedge and random partitions, Selecta Math., New Ser.7(2001), 57–81. Our first result is that the correlation functions of the Schur process are determinants with a kernel that has a nice contour integral representation in terms of the parameters of the process. This general result is then applied to a particular specialization of the Schur process, namely to random 3-dimensional Young diagrams. The local geometry of a large random 3-dimensional diagram is described in terms of a determinantal point process on a 2-dimensional lattice with the incomplete beta function kernel (which generalizes the discrete sine kernel). A brief discussion of the universality of this answer concludes the paper.
Infinitely many hyperbolic 3-manifolds which contain no Reebless foliation
Authors: Roberts R. , Shareshian J. , Stein M.
Published: March 2003

We investigate group actions on simply-connected (second countable but not necessarily Hausdorff) 1-manifolds and describe an infinite family of closed hyperbolic 3-manifolds whose fundamental groups do not act nontrivially on such 1-manifolds. As a corollary we conclude that these 3-manifolds contain no Reebless foliation. In fact, these arguments extend to actions on oriented

R

\mathbb R

-order trees and hence these 3-manifolds contain no transversely oriented essential lamination; in particular, they are non-Haken.
A comparison of online and postal data collection methods in marketing research
Authors: McDonald Heath , Adam Stewart
Published: March 2003

The widespread acceptance of the use of online techniques in market research necessitates appreciation of the relative advantages and disadvantages of these techniques over more traditional research methods. This paper reports on a study which directly compares online and postal data collection methods using the same survey instrument on two samples drawn from the same population of football club subscribers. The results confirm that the online and postal respondents are demographically different. Online data collection is shown to be less expensive per respondent and that data collection is faster, however, an overall lower response level is achieved relative to the postal data collection method. Of greater importance, though, are the findings that respondents seem to answer questions differently online than they do via postal methods. The conclusion here is that online data collection should not be treated as a direct substitute for postal data collection in every instance.
Dynamic T‐search for accelerating searching speeds in Delaunay triangulation
Authors: Yoon Sugjoon
Published: March 2003

For realistic simulation of off‐road vehicles terrain surfaces have to be modeled in detail, and wheel‐surface contacting geometry must be well defined in order to obtain proper ground‐reaction and friction forces. Delaunay triangulation is one of the most widely used methods in modeling 3D terrain surfaces, and triangle‐search (T‐search) is a relevant algorithm for searching resultant triangular polygons. The T‐search method searches polygons in successive order and may not allow real‐time computation of off‐road vehicle dynamics if the terrain is modeled with many polygons, depending on the computer performance used in the simulation. Dynamic T‐search, which is proposed in this paper, combines conventional T‐search and the concept of a dynamic window, which is a moving subset of the database and where an actual search is made at each frame, by taking advantage of the information regarding dynamic characteristics of a simulated vehicle. Numerical tests show improvement of searching speeds by about 5 percent for randomly distributed triangles. For continuous searches along a vehicle path, which actually occur in a vehicle simulation, the searching speed of the new method becomes four times faster than the conventional one.
Innovation and TQM in Swedish higher education institutions – possibilities and pitfalls
Authors: Wiklund Håkan , Klefsjö Bengt , Sandvik Wiklund Pia , Edvardsson Bo
Published: March 2003

Emphasis on quality improvement has been one of the most characteristic features of higher education policy in Nordic and other European countries during the 1990s. In Sweden, the universities’ work with quality management has been evaluated for several years. In January 2001, the National Agency of Higher Education in Sweden introduced a new comprehensive system for quality assessment. The Swedish assessment system stresses that the assessment should have as a corner‐stone the specific prerequisites for each university and subject, e.g. business administration and their development strategy. The comprehensive quality assessments of Swedish higher education institutions are discussed together with stimulating innovation and continuous improvement of higher education.
Corporate decision making: contending perspectives and their governance implications
Authors: Dixon John , Dogan Rhys
Published: March 2003

Recently in this Journal, Cutting and Kouzmin postulated a three‐phase group decision‐making process. This paper demarcates, within that framework, a set of contending corporate board decision‐making perceptions. It’s premise is that how directors determine how investigations should be conducted, evidence should be assessed, and the truth should be decided depends on their epistemological and ontological predisposition. The philosophy of the social sciences offers four contending epistemological and ontological lens used to describe, analyze, evaluate and judge their corporate world. Each is fundamentally flawed. What is needed, then, are reflexive and pluralized corporate governance structures and processes that can accommodate a variety of epistemological and ontological imperatives. The broad conclusion drawn is that good corporate governance requires directors to recognize the limitations of their understanding of corporate governance reality, to treat all truth claims skeptically, and never to resort to self‐deception or self‐delusion just to avoid unpleasant corporate governance truths.
Some properties of photon scattering in water phantoms in diagnostic radiology
Authors: Chan Heang‐Ping , Doi Kunio
Published: March 2003

Monte Carlo simulation was applied to study the histories of photon interactions in a soft‐tissue‐equivalent medium under diagnostic imaging conditions. We examined the dependence on incident x‐ray energy and phantom thickness of the basic properties of photon scattering, including the probabilities of occurrence of the various interaction processes, and the frequency distributions of scattering events. We investigated the properties of scattered radiation for monoenergetic incident x rays, which provide a basis for deriving the physical properties of scattered radiation for any polyenergetic incident beam. We also included four incident x‐ray beams with broad spectra; these represented the incident x rays typically used for diagnostic imaging.