bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sociopolitical Development as an Antidote for Oppression—Theory and Action
Authors: Watts Roderick J. , Griffith Derek M. , Abdul-Adil Jaleel 
Published: April 2003

AbstractAlthough psychology has an ample vocabulary for describing individual pathologies, the development of theory and concepts for understanding societal pathology remains in its infancy. Because community psychology theory views human behavior in its context, it is essential that interventions not be limited to stress management, personal coping, and similar programming. Interventions should not leave social injustice undiscussed and unchallenged. In this spirit we present a theory of oppression and sociopolitical development that informs an intervention with young, African American men in an urban setting. The five‐stage theory highlights the role of Freire's notion of “critical consciousness,” a sociopolitical version of critical thinking, in enhancing an awareness of sociopolitical as well as personal forces that influence behavior. The theory also draws on African American social‐change traditions and their spiritual aspects. The action section of the study describes the Young Warriors program's use of mass culture (rap videos and film) as stimuli for the development of critical consciousness. Highlights from an empirical investigation of an eight‐session high school version of the program will be presented to illustrate the practical challenges and benefits of sociopolitical interventions.
A Risk‐Amplification Model of Victimization and Depressive Symptoms Among Runaway and Homeless Adolescents
Authors: Whitbeck Les B. , Hoyt Dan R. , Yoder Kevin A. 
Published: April 2003

AbstractThis report is an examination of a theoretical model of risk amplification within a sample of 255 homeless and runaway adolescents. The young people were interviewed on the streets and in shelters in urban centers of four Midwestern states. Separate models were examined for males (n = 102) and females (n = 153). Results indicated that street experiences such as affiliation with deviant peers, deviant subsistence strategies, risky sexual behaviors, and drug and/or alcohol use amplified the effects of early family abuse on victimization and depressive symptoms for young women. These street adaptations significantly increased the likelihood of serious victimization over and above the effects of early family history for both young men and women. Similarly, street behaviors and experiences increased the likelihood of depressive symptoms for young women over the effects of early family abuse, but not for young men. The risk‐amplification model from the life course theoretical perspective is discussed as an example of the cumulative continuity of maladaptive behaviors.
On the density of the set of generators of a polynomial algebra
Authors: Drensky Vesselin , Shpilrain Vladimir , Yu Jie-Tai 
Published: March 2003

Let

K
[
X
]
=
K
[

x
1

,
.
.
.
,

x
n

]
,

n
≥
2
,

K[X] = K[x_1,...,x_n], ~n \ge 2,

be the polynomial algebra over a field

K
K

of characteristic

0
0

. We call a polynomial

p
∈
K
[
X
]

~p \in K[X]

coordinate (or a generator) if

K
[
X
]
=
K
[
p
,

p
2

,
.
.
.
,

p
n

]

K[X] = K[p, p_2, ..., p_n]

for some polynomials

p
2

,
.
.
.
,

p
n

~p_2, ..., p_n

. In this note, we give a simple proof of the following interesting fact: for any polynomial

h

~h~

of the form

(

x
i

+
q
)
,

~(x_i + q),

where

q
q

is a polynomial without constant and linear terms, and for any integer

m
≥
2

~m \ge 2

, there is a coordinate polynomial

p

~p~

such that the polynomial

(
p
−
h
)

(p-h)

has no monomials of degree

≤
m

\leq m

. A similar result is valid for coordinate

k
k

-tuples of polynomials, for any

k
>
n

k > n

. This contrasts sharply with the situation in other algebraic systems. On the other hand, we establish (in the two-variable case) a result related to a different kind of density. Namely, we show that given a non-coordinate two-variable polynomial, any sufficiently small perturbation of its non-zero coefficients gives another non-coordinate polynomial.
Weak type estimates for cone multipliers on 𝐻^{𝑝} spaces, 𝑝<1
Authors: Hong Sunggeum 
Published: March 2003

We consider operators

T

δ

T^{\delta }

associated with the Fourier multipliers

(

1
−

|

ξ

′

|

2

ξ

n
+
1

2

)

+

δ

,

(

ξ

′

,

ξ

n
+
1

)
∈

R

n

×

R

,

\begin{equation*}{\bigg (}1- \frac {|{\xi }’|^{2}}{{\xi }_{n+1}^{2}} {\bigg )}_{+}^{\delta },\quad \quad ({\xi }’,\xi _{n+1}) \in {\mathbb R}^{n} \times {\mathbb R},\end{equation*}

and show that

T

δ

T^{\delta }

is of weak type

(
p
,
p
)

(p,p)

on

H

p

(

R

n
+
1

)

H^{p}({\mathbb R}^{n+1})

,

0
>
p
>
1

0 > p > 1

, for the critical value

δ
=
n
(

1
p

−

1
2

)
−

1
2

\delta = n(\frac {1}{p}-\frac {1}{2}) - \frac {1}{2}

.
Strongly asymptotically stable Frobenius-Perron operators
Authors: Zaharopol Radu 
Published: March 2003

Let

(
X
,
Σ
,
μ
)

(X,\Sigma ,\mu )

be a

σ
\sigma

-finite measure space and let

T
:

L
1

(
X
,
Σ
,
μ
)
→

L
1

(
X
,
Σ
,
μ
)

T : L^1(X,\Sigma ,\mu ) \to L^1(X,\Sigma ,\mu )

be a Frobenius-Perron operator. In 1997 Bartoszek and Brown proved that if

T
T

overlaps supports and if there exists

h
∈

L
1

(
X
,
Σ
,
μ
)

h \in L^1(X,\Sigma ,\mu )

,

h
>
0

h > 0

on

X
X

, such that

T
h
=
h

Th = h

, then

T
T

is (strongly) asymptotically stable. In the note we prove that instead of assuming that

h
>
0

h > 0

on

X
X

, it is enough to assume that

h
≥
0

h\geq 0

and

h
≠
0

h\neq 0

. More precisely, we prove that

T
T

is asymptotically stable if and only if

T
T

overlaps supports and there exists

h
∈

L
1

(
X
,
Σ
,
μ
)

h\in L^1(X,\Sigma ,\mu )

,

h
≥
0

h\geq 0

,

h
≠
0

h\neq 0

, such that

T
h
=
h

Th=h

.
Lamé differential equations and electrostatics
Authors: Dimitrov Dimitar , Van Assche Walter 
Published: March 2003

The problem of existence and uniqueness of polynomial solutions of the Lamé differential equation

A
(
x
)

y

′
′

+
2
B
(
x
)

y
′

+
C
(
x
)
y
=
0
,

\begin{equation*} A(x) y^{\prime \prime } + 2 B(x) y’ + C(x) y = 0, \end{equation*}

where

A
(
x
)
,
B
(
x
)

A(x), B(x)

and

C
(
x
)

C(x)

are polynomials of degree

p
+
1
,
p

p+1, p

and

p
−
1

p-1

, is under discussion. We concentrate on the case when

A
(
x
)

A(x)

has only real zeros

a

j

a_{j}

and, in contrast to a classical result of Heine and Stieltjes which concerns the case of positive coefficients

r

j

r_{j}

in the partial fraction decomposition

B
(
x
)

/

A
(
x
)
=

∑

j
=
0

p

r

j

/

(
x
−

a

j

)

B(x)/A(x) = \sum _{j=0}^{p} r_{j}/(x-a_{j})

, we allow the presence of both positive and negative coefficients

r

j

r_{j}

. The corresponding electrostatic interpretation of the zeros of the solution

y
(
x
)

y(x)

as points of equilibrium in an electrostatic field generated by charges

r

j

r_{j}

at

a

j

a_{j}

is given. As an application we prove that the zeros of the Gegenbauer-Laurent polynomials are the points of unique equilibrium in a field generated by two positive and two negative charges.
Composition operators on Dirichlet-type spaces
Authors: Hibschweiler R. 
Published: March 2003

The Dirichlet-type space

D

p

(
1
≤
p
≤
2

D^{p}\ (1 \leq p \leq 2

) is the Banach space of functions analytic in the unit disc with derivatives belonging to the Bergman space

A

p

A^{p}

. Let

Φ
\Phi

be an analytic self-map of the disc and define

C

Φ

(
f
)
=
f
∘
Φ

C_{\Phi }(f) = f \circ \Phi

for

f
∈

D

p

f \in D^{p}

. The operator

C

Φ

:

D

p

→

D

p

C_{\Phi }: D^{p} \rightarrow D^{p}

is bounded (respectively, compact) if and only if a related measure

μ

p

\mu _{p}

is Carleson (respectively, compact Carleson). If

C

Φ

C_{\Phi }

is bounded (or compact) on

D

p

D^{p}

, then the same behavior holds on

D

q

(
1
≤
q
>
p

D^{q}\ (1 \leq q > p

) and on the weighted Dirichlet space

D

2
−
p

D_{2-p}

. Compactness on

D

p

D^{p}

implies that

C

Φ

C_{\Phi }

is compact on the Hardy spaces and the angular derivative exists nowhere on the unit circle. Conditions are given which, together with the angular derivative condition, imply compactness on the space

D

p

D^{p}

. Inner functions which induce bounded composition operators on

D

p

D^{p}

are discussed briefly.
On wavelets interpolated from a pair of wavelet sets
Authors: Rzeszotnik Ziemowit , Speegle Darrin 
Published: March 2003

We show that any wavelet, with the support of its Fourier transform small enough, can be interpolated from a pair of wavelet sets. In particular, the support of the Fourier transform of such wavelets must contain a wavelet set, answering a special case of an open problem of Larson. The interpolation procedure, which was introduced by X. Dai and D. Larson, allows us also to prove the extension property.
Asymptotics of Sobolev embeddings and singular perturbations for the 𝑝-Laplacian
Authors: del Pino Manuel , Flores César 
Published: March 2003

We consider the best constant

S
(

Ω
λ

)

S(\Omega _\lambda )

for the embedding of

W

1
,
p

(

Ω
λ

)

W^{1,p} (\Omega _\lambda )

into

L
q

(

Ω
λ

)

L^q(\Omega _\lambda )

where

1
>
p
>
2

1>p>2

,

p
>
q
>

N
p

N
−
p

p>q> {Np\over N-p}

. Here

Ω
λ

=
λ
Ω

\Omega _\lambda = \lambda \Omega

with

Ω
\Omega

a smooth, bounded domain in

R

n

\mathbb {R}^n

and

λ
\lambda

a large positive number. It is proven by the validity of the expansion

S
(

Ω
λ

)
=
S
(

R

+
n

)
−

λ

−
1

γ

max

x
∈
∂
Ω

H
(
x
)
+
o
(

λ

−
1

)
,

\begin{equation} S( \Omega _\lambda ) = S(\mathbb {R}^n_+) - \lambda ^{-1} \gamma \max _{x\in \partial \Omega } H(x) + o ( \lambda ^{-1} ), \nonumber \end{equation}

as

λ
→
∞

\lambda \to \infty

, where

γ
\gamma

is a positive constant depending on

p
,
q

p,q

and

N
N

. The behavior of associated extremals, which satisfy an equation involving the

p
p

-Laplacian operator, is also analyzed.
A Cluster of Genes Encodes the Two Types of Chalcone Isomerase Involved in the Biosynthesis of General Flavonoids and Legume-Specific 5-Deoxy(iso)flavonoids in Lotus japonicus
Authors: Shimada Norimoto , Aoki Toshio , Sato Shusei , Nakamura Yasukazu , Tabata Satoshi , Ayabe Shin-ichi 
Published: March 2003

Abstract
Leguminous plants produce 5-deoxyflavonoids and 5-deoxyisoflavonoids that play essential roles in legume-microbe interactions. Together with chalcone polyketide reductase and cytochrome P450 2-hydroxyisoflavanone synthase, the chalcone isomerase (CHI) of leguminous plants is fundamental in the construction of these ecophysiologically active flavonoids. Although CHIs of nonleguminous plants isomerize only 6′-hydroxychalcone to 5-hydroxyflavanone (CHIs with this function are referred to as type I), leguminous CHIs convert both 6′-deoxychalcone and 6′-hydroxychalcone to 5-deoxyflavanone and 5-hydroxyflavanone, respectively (referred to as type II). In this study, we isolated multiple CHI cDNAs (cCHI1–cCHI3) from a model legume,Lotus japonicus. In contrast to previous observations, the amino acid sequence of CHI2 was highly homologous to nonleguminous CHIs, whereas CHI1 and CHI3 were the conventional leguminous type. Furthermore, genome sequence analysis revealed that fourCHI genes (CHI1–3 and a putative gene, CHI4) form a tandem cluster within 15 kb. Biochemical analysis with recombinant CHIs expressed inEscherichia coli confirmed that CHI1 and CHI3 are type II CHIs and that CHI2 is a type I CHI. The occurrence of both types of CHIs is probably common in leguminous plants, and it was suggested that type II CHIs evolved from an ancestral CHI by gene duplication and began to produce 5-deoxy(iso)flavonoids along with the establishment of the Fabaceae.
Nod Factor Elicits Two Separable Calcium Responses inMedicago truncatula Root Hair Cells
Authors: Shaw Sidney L. , Long Sharon R. 
Published: March 2003

Abstract
Modulation of intracellular calcium levels plays a key role in the transduction of many biological signals. Here, we characterize early calcium responses of wild-type and mutant Medicago truncatula plants to nodulation factors produced by the bacterial symbiont Sinorhizobium meliloti using a dual-dye ratiometric imaging technique. When presented with 1 nm Nod factor, root hair cells exhibited only the previously described calcium spiking response initiating 10 min after application. Nod factor (10 nm) elicited an immediate increase in calcium levels that was temporally earlier and spatially distinct from calcium spikes occurring later in the same cell. Nod factor analogs that were structurally related, applied at 10 nm, failed to initiate this calcium flux response. Cells induced to spike with low Nod factor concentrations show a calcium flux response when Nod factor is raised from 1 to 10 nm. Plant mutants previously shown to be deficient for the calcium spiking response (dmi1 and dmi2) exhibited an immediate, truncated calcium flux with 10 nm Nod factor, demonstrating a competence to respond to Nod factor but an impaired ability to generate a full biphasic response. These results demonstrate that the legume root hair cell exhibits two independent calcium responses to Nod factor triggered at different agonist concentrations and suggests an early branch point in the Nod factor signal transduction pathway.
Expression of an Expansin Gene Is Correlated with Root Elongation in Soybean
Authors: Lee Dong-Keun , Ahn Ji Hoon , Song Sang-Kee , Choi Yang Do , Lee Jong Seob 
Published: March 2003

Abstract
Expansin is a family of proteins that catalyze long-term expansion of cell walls and has been considered a principal protein that affects cell expansion in plants. We have identified the first root-specific expansin gene in soybean (Glycine max),GmEXP1, which may be responsible for root elongation. Expression levels of GmEXP1 were very high in the roots of 1- to 5-d-old seedlings, in which rapid root elongation takes place. Furthermore, GmEXP1 mRNA was most abundant in the root tip region, where cell elongation occurs, but scarce in the region of maturation, where cell elongation ceases, implying that its expression is closely related to root development processes. In situ hybridization showed that GmEXP1 transcripts were preferentially present in the epidermal cells and underlying cell layers in the root tip of the primary and secondary roots. Ectopic expression ofGmEXP1 accelerated the root growth of transgenic tobacco (Nicotiana tabacum) seedlings, and the roots showed insensitivity to obstacle-touching stress. These results imply that theGmEXP1 gene plays an important role in root development in soybean, especially in the elongation and/or initiation of the primary and secondary roots.
The Arabidopsis Mutant alh1 Illustrates a Cross Talk between Ethylene and Auxin
Authors: Vandenbussche Filip , Smalle Jan , Le Jie , Saibo Nelson José Madeira , De Paepe Annelies , Chaerle Laury , Tietz Olaf , Smets Raphael , Laarhoven Lucas J.J. , Harren Frans J.M. , Van Onckelen Harry , Palme Klaus , Verbelen Jean-Pierre , Van Der Straeten Dominique 
Published: March 2003

Abstract
Ethylene or its precursor 1-aminocyclopropane-1-carboxylic acid (ACC) can stimulate hypocotyl elongation in light-grown Arabidopsis seedlings. A mutant, designated ACC-related long hypocotyl 1 (alh1), that displayed a long hypocotyl in the light in the absence of the hormone was characterized. Etiolatedalh1 seedlings overproduced ethylene and had an exaggerated apical hook and a thicker hypocotyl, although no difference in hypocotyl length was observed when compared with wild type.Alh1 plants were less sensitive to ethylene, as reflected by reduction of ACC-mediated inhibition of hypocotyl growth in the dark and delay in flowering and leaf senescence.Alh1 also had an altered response to auxin, whereas auxin levels in whole alh1 seedlings remained unaffected. In contrast to wild type, alh1 seedlings showed a limited hypocotyl elongation when treated with indole-3-acetic acid. Alh1 roots had a faster response to gravity. Furthermore, the hypocotyl elongation of alh1 and of ACC-treated wild type was reverted by auxin transport inhibitors. In addition, auxin up-regulated genes were ectopically expressed in hypocotyls upon ACC treatment, suggesting that the ethylene response is mediated by auxins. Together, these data indicate thatalh1 is altered in the cross talk between ethylene and auxins, probably at the level of auxin transport.
4-Coumarate:Coenzyme A Ligase Has the Catalytic Capacity to Synthesize and Reuse Various (Di)Adenosine Polyphosphates
Authors: Pietrowska-Borek Małgorzata , Stuible Hans-Peter , Kombrink Erich , Guranowski Andrzej 
Published: March 2003

Abstract
4-Coumarate:coenzyme A ligase (4CL) is known to activate cinnamic acid derivatives to their corresponding coenzyme A esters. As a new type of 4CL-catalyzed reaction, we observed the synthesis of various mono- and diadenosine polyphosphates. Both the native 4CL2 isoform from Arabidopsis (At4CL2 wild type) and the At4CL2 gain of function mutant M293P/K320L, which exhibits the capacity to use a broader range of phenolic substrates, catalyzed the synthesis of adenosine 5′-tetraphosphate (p4A) and adenosine 5′-pentaphosphate when incubated with MgATP−2 and tripolyphosphate or tetrapolyphosphate (P4), respectively. Diadenosine 5′,5‴,-P1,P4-tetraphosphate represented the main product when the enzymes were supplied with only MgATP2−. The At4CL2 mutant M293P/K320L was studied in more detail and was also found to catalyze the synthesis of additional dinucleoside polyphosphates such as diadenosine 5′,5‴-P1,P5-pentaphosphate and dAp4dA from the appropriate substrates, p4A and dATP, respectively. Formation of Ap3A from ATP and ADP was not observed with either At4CL2 variant. In all cases analyzed, (di)adenosine polyphosphate synthesis was either strictly dependent on or strongly stimulated by the presence of a cognate cinnamic acid derivative. The At4CL2 mutant enzyme K540L carrying a point mutation in the catalytic center that is critical for adenylate intermediate formation was inactive in both p4A and diadenosine 5′,5‴,-P1,P4-tetraphosphate synthesis. These results indicate that the cinnamoyl-adenylate intermediate synthesized by At4CL2 not only functions as an intermediate in coenzyme A ester formation but can also act as a cocatalytic AMP-donor in (di)adenosine polyphosphate synthesis.
A Novel Cl− Inward-Rectifying Current in the Plasma Membrane of the Calcifying Marine Phytoplankton Coccolithus pelagicus
Authors: Taylor Alison R. , Brownlee Colin 
Published: March 2003

Abstract
We investigated the membrane properties and dominant ionic conductances in the plasma membrane of the calcifying marine phytoplankton Coccolithus pelagicus using the patch-clamp technique. Whole-cell recordings obtained from decalcified cells revealed a dominant anion conductance in response to membrane hyperpolarization. Ion substitution showed that the anion channels were selective for Cl− and Br− over other anions, and the sensitivity to the stilbene derivative 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid, ethacrynic acid, and Zn2+ revealed a pharmacological profile typical of many plant and animal anion channels. Voltage activation and kinetic characteristics of the C. pelagicusCl− channel are consistent with a novel function in plants as the inward rectifier that tightly regulates membrane potential. Membrane depolarization gave rise to nonselective cation currents and in some cases evoked action potential currents. We propose that these major ion conductances play an essential role in membrane voltage regulation that relates to the unique transport physiology of these calcifying phytoplankton.
A Diffusible Factor from Arbuscular Mycorrhizal Fungi Induces Symbiosis-Specific MtENOD11 Expression in Roots ofMedicago truncatula
Authors: Kosuta Sonja , Chabaud Mireille , Lougnon Géraldine , Gough Clare , Dénarié Jean , Barker David G. , Bécard Guillaume 
Published: March 2003

Abstract
Using dual cultures of arbuscular mycorrhizal (AM) fungi andMedicago truncatula separated by a physical barrier, we demonstrate that hyphae from germinating spores produce a diffusible factor that is perceived by roots in the absence of direct physical contact. This AM factor elicits expression of the Nod factor-inducible gene MtENOD11, visualized using a pMtENOD11-gusA reporter. Transgene induction occurs primarily in the root cortex, with expression stretching from the zone of root hair emergence to the region of mature root hairs. All AM fungi tested (Gigaspora rosea,Gigaspora gigantea, Gigaspora margarita, and Glomus intraradices) elicit a similar response, whereas pathogenic fungi such as Phythophthora medicaginis, Phoma medicaginis var pinodella andFusarium solani f.sp. phaseoli do not, suggesting that the observed root response is specific to AM fungi. Finally, pMtENOD11-gusA induction in response to the diffusible AM fungal factor is also observed with all threeM. truncatulaNod−/Myc− mutants (dmi1,dmi2, and dmi3), whereas the same mutants are blocked in their response to Nod factor. This positive response of the Nod−/Myc− mutants to the diffusible AM fungal factor and the different cellular localization of pMtENOD11-gusA expression in response to Nod factor versus AM factor suggest that signal transduction occurs via different pathways and that expression of MtENOD11 is differently regulated by the two diffusible factors.
Regulation of Root Elongation under Phosphorus Stress Involves Changes in Ethylene Responsiveness
Authors: Ma Zhong , Baskin Tobias I. , Brown Kathleen M. , Lynch Jonathan P. 
Published: March 2003

Abstract
We characterized the growth of the primary root of Arabidopsis under phosphorus sufficiency (1 mm phosphate) and deficiency (1 μm phosphate), focusing on the role of ethylene. We quantified the spatial profile of relative elongation with a novel method based on image processing, as well as the production rates of cortical cells, trichoblasts, and atrichoblasts. Phosphorus deficiency moderately decreased the maximal rate of relative elongation, shortened the growth zone, and decreased the production rate of both epidermal cell types but not of cortical cells. Inhibiting ethylene production (with aminoethoxyvinyl-glycine) or action (with 1-methylcyclopropene) increased elongation in high phosphorus and decreased it in low phosphorus. That these effects were specific to ethylene was confirmed by negating the effect of inhibited ethylene production with simultaneous treatment with an ethylene precursor (1-aminocyclopropane-1-carboxylic acid). Under both phosphorus regimes, ethylene regulated the maximal rate of relative elongation rather than the size of the growth zone. In addition, inhibiting ethylene action in high versus low phosphorus elicited opposite responses for the position of root hair initiation and for the production rates of cortex cells and atrichoblasts. We conclude that the root system acclimates to phosphorus deficiency by changing the signal transduction pathway connecting ethylene levels to growth and division.