bluuebunny/crossref_metadata_2025_split huggingface dataset:
Waisman Center
Authors: Seltzer Marsha Mailick 
Published: September 2002

AbstractThe Waisman Center MRDDRC supports behavioral, social, and biomedical research on human development, developmental disabilities, and neurodegenerative diseases. Examples of research conducted in each of the four MRDDRC units include: abnormalities in gene expression in human neuronal stem cells and progenitor cells from Down syndrome tissue (from the Molecular and Genetic Sciences Unit), language disorders in adolescents with Down syndrome and Fragile X syndrome (from the Communication Processes Unit); the development of selective visual attention during the first 6 months of life (from the Sensory and Cognitive Processes Unit); and the long‐range effects of early intervention on special education placement, delinquency, and high school graduation rates (from the Social and Affective Processes Unit).
Extracellular factors that regulate neuronal migration in the central nervous system
Authors: Sobeih Magdi M. , Corfas Gabriel 
Published: September 2002

AbstractNeuronal migration is an essential process in the development of the central nervous system (CNS). The movement of neuronal precursors from their birthplaces to their ultimate position in the adult brain is regulated by extrinsic and intrinsic signals. The understanding of the extracellular factors that regulate neuronal migration has increased significantly in the last few years. In this review, we will discuss the latest insights into the roles of the extracellular matrix (ECM), cell adhesion molecules (CAMs), soluble and membrane‐bound factors, neurotransmitters and ion channels in the migration of neurons.
Microarray analysis of normal and dystrophic skeletal muscle
Authors: Haslett Judith N. , Kunkel Louis M. 
Published: September 2002

AbstractThe development and increasingly common use of DNA microarrays for comprehensive RNA expression analysis has had a substantial impact on the study of molecular pathology. DNA microarrays are orderly, high‐density arrangements of nucleic acid spots that can be used as substrates for global gene expression analysis. Prior to their development, technical limitations necessitated that the molecular mechanisms underlying biological processes be broken down into their component parts and each gene or protein studied individually. This approach, focused as it is on a single aspect of a scientific phenomenon, does not allow appreciation or understanding of the fact that biological pathways do not exist in isolation, but are influenced by numerous factors. Enormous technological advances have been made over the past decade and now high‐density DNA microarrays can provide rapid measurement of thousands of distinct transcripts simultaneously. These experiments raise the exciting opportunity to examine biological pathways in all their complexity and to compare the hypotheses deduced from the study of histological pathology with the findings of molecular pathology. This review focuses on how microarray technology has been used to interrogate muscular gene expression and, in particular, on how data generated from differential expression analysis of dystrophic and normal skeletal muscle has contributed to understanding the molecular pathophysiological pathways of muscular dystrophy.
Influence of vortex-pairing location on the
three-dimensional evolution of plane mixing
layers
Authors: ESTEVADEORDAL JORDI , KLEIS STANLEY J. 
Published: September 2002

Detailed three-dimensional measurements of the first vortex pairing of a large plane
mixing layer reveal excitation of several three-dimensional instability modes. Time
evolution in three-dimensional space (x, y, z, t) shows how the two-dimensional rollers
become three-dimensional as they approach each other and that the linear growth
of at least two instability waves leads to a spanwise periodic pairing. The results
are based on phase-locked measurements made in three-dimensional spatial grids,
with a mesh spacing of 8.5% of the fundamental instability wavelength. Spanwise-uniform,
periodic acoustic excitation stabilizes the most probable two-dimensional
natural features – roll-up and first pairing. The second subharmonic is added to
study the effect of alternate streamwise pairing locations on the three-dimensional
characteristics of vortex pairing. Velocities are measured using hot-wire anemometry,
and the coherent structures are reconstructed from the ensemble-averaged vorticity
field.Vortex pairing is shown to initiate through local ‘bridging’ at the maxima of
periodic spanwise undulations. The undulations result from linear amplification of
various instability modes on pairing rollers having different strengths. Bridging results
from the change of the relative phase between the spanwise undulations of the pairing
rollers from in-phase (due to the initial translative mode) to out-of-phase (due to the
amplification of bulging-like and non-axisymmetric modes). It is found that when
pairing occurs sufficiently far upstream, only axisymmetric waves are amplified and
the evolution results in axisymmetric merging. In contrast, when pairing occurs
sufficiently far downstream, both axisymmetric and non-axisymmetric waves are
amplified and the evolution results in non-axisymmetric merging.The results indicate that vortex pairing is accompanied by the counter-rotating
pairs of secondary structures (‘streamwise vortices’ or ‘ribs’) located in the mixing-layer
braids and residing in the valleys of the spanwise-roller waves. Time evolution of
these secondary structures shows that they move in the transverse direction, following
the rollers.
The influence of geometry on inviscid
decay rates in haemodynamic flows
Authors: BLYTH M. G. , MESTEL A. J. 
Published: September 2002

Fully developed flows are often used to describe fluid motion in complex geometrical
systems, including the human macrocirculation. In fact they may frequently be quite
inappropriate even for geometrically simple pipes, owing to the unfeasibly large
viscous entry lengths required. Inviscid adjustment to changes in geometry, however,
occurs on the lengthscale of the pipe diameter. Inviscid idealizations are therefore
more likely to apply in relatively short arterial sections. We aim to quantify the
distances involved by calculating the rates of spatial decay for a general disturbance
superimposed on an idealized base flow. Both irrotational and rotational base flows
are examined, although in the latter case there can exist non-decaying inertial waves,
so that an arbitrary inflow need not attain an inviscid state independent of the
downstream coordinate. In the rotational case, we therefore restrict attention to those
flows which settle down to perturbations of such a state, whereas the potential flows
can be regarded as developing from an arbitrary input.We focus on the last surviving mode of decay in simple uniform pipe geometries,
in particular a straight pipe, part of a torus, and a helical pipe. In this way we are
able to assess the effects of curvature and torsion on the inviscid entry lengths.Principally, it is shown that the rate of decay is fastest in a straight pipe and slowest
in a toroidal pipe, with that in a helical pipe somewhere in between. Core vorticity
tends to reduce the decay rate. If an idealized flow occurs in a geometrically simple
arterial portion, our results determine its domain of validity.
Airway closure: surface-tension-driven
non-axisymmetric instabilities of liquid-lined
elastic rings
Authors: HEIL MATTHIAS , WHITE JOSEPH P. 
Published: September 2002

This paper investigates the stability and large-displacement post-buckling behaviour
of liquid-lined elastic rings. The fluid flow and the wall deformation are described
by the free-surface Navier–Stokes equations and by geometrically nonlinear shell
theory, respectively. The fluid–structure interaction problem is solved numerically
by a finite element method. The compressive load on the ring is a combination of
the external pressure and the effect of surface tension. Once this combined load
exceeds a critical value, the subsequent non-axisymmetric collapse of the ring is
controlled by the dynamics of the surface-tension-driven redistribution of fluid in
the liquid lining. It is shown that, for sufficiently large surface tension, the ring can
undergo a catastrophic collapse which leads to a complete occlusion of its lumen. A
novel lubrication theory model, which ensures exact volume conservation for flows
on strongly curved substrates, is developed and found to be capable of accurately
describing the motion of the air–liquid interface and the fluid–structure interaction in
the large-displacement regime, even in cases where the film thickness is large.The findings have important implications for the occurrence of airway closure in
lung diseases (such as oedema) which cause an increase in the thickness of the airways'
liquid lining. It is shown that under such conditions, airways can become occluded
even if the volume of fluid in their liquid lining is much smaller than that required to
occlude them in their axisymmetric state.
Anisotropic enhancement of turbulence in
large-scale, low-intensity turbulent premixed
propane–air flames
Authors: FURUKAWA JUNICHI , NOGUCHI YOSHIKI , HIRANO TOSHISUKE , WILLIAMS FORMAN A. 
Published: September 2002

The density change across premixed flames propagating in turbulent flows modifies
the turbulence. The nature of that modification depends on the regime of turbulent
combustion, the burner design, the orientation of the turbulent flame and the position
within the flame. The present study addresses statistically stationary turbulent combustion
in the flame-sheet regime, in which the laminar-flame thickness is less than
the Kolmogorov scale, for flames stabilized on a vertically oriented cylindrical burner
having fully developed upward turbulent pipe flow upstream from the exit. Under
these conditions, rapidly moving wrinkled laminar flamelets form the axisymmetric
turbulent flame brush that is attached to the burner exit. Predictions have been made
of changes in turbulence properties across laminar flamelets in such situations, but
very few measurements have been performed to test the predictions. The present work
measures individual velocity changes and changes in turbulence across flamelets at
different positions in the turbulent flame brush for three different equivalence ratios,
for comparison with theory.The measurements employ a three-element electrostatic probe (EP) and a two-component
laser-Doppler velocimeter (LDV). The LDV measures axial and radial
components of the local gas velocity, while the EP, whose three sensors are located
in a vertical plane that passes through the burner axis, containing the plane of the
LDV velocity components, measures arrival times of flamelets at three points in that
plane. From the arrival times, the projection of flamelet orientation and velocity on
the plane are obtained. All of the EP and LDV sensors are located within a fixed
volume element of about 1 mm diameter to provide local, time-resolved information.
The technique has the EP advantages of rapid response and good sensitivity and
the EP disadvantages of intrusiveness and complexity of interpretation, but it is well
suited to the type of data sought here.Theory predicts that the component of velocity tangent to the surface of a locally
planar flamelet remains constant in passing through the flamelet. The data are
consistent with this prediction, within the accuracy of the measurement. The data
also indicate that the component of velocity normal to the flamelet, measured with
respect to the flamelet, tends to increase in passing through the flamelet, as expected.
The flamelets thereby can generate anisotropy in initially isotropic turbulence. They
also produce differences in turbulent spectra conditioned on unburnt or burnt gas.
Local modifications of turbulence by flamelets thus are demonstrated experimentally.
The modifications are quantitatively different at different locations in the turbulent
flame brush but qualitatively similar in that the turbulence is enhanced more strongly
in the radial direction than in the axial direction at all positions in these flames.
Once again on the supersonic flow separation
near a corner
Authors: KOROLEV G. L. , GAJJAR J. S. B. , RUBAN A. I. 
Published: September 2002

Laminar boundary-layer separation in the supersonic flow past a corner point on
a rigid body contour, also termed the compression ramp, is considered based on
the viscous–inviscid interaction concept. The ‘triple-deck model’ is used to describe
the interaction process. The governing equations of the interaction may be formally
derived from the Navier–Stokes equations if the ramp angle θ is represented as θ =
θ0Re−1/4, where θ0 is an order-one quantity and Re is the Reynolds number, assumed
large. To solve the interaction problem two numerical methods have been used. The
first method employs a finite-difference approximation of the governing equations
with respect to both the streamwise and wall-normal coordinates. The resulting
algebraic equations are linearized using a Newton–Raphson strategy and then solved
with the Thomas-matrix technique. The second method uses finite differences in
the streamwise direction in combination with Chebychev collocation in the normal
direction and Newton–Raphson linearization.Our main concern is with the flow behaviour at large values of θ0. The calculations
show that as the ramp angle θ0 increases, additional eddies form near the corner
point inside the separation region. The behaviour of the solution does not give any
indication that there exists a critical value θ*0 of the ramp angle θ0, as suggested
by Smith & Khorrami (1991) who claimed that as θ0 approaches θ*0, a singularity
develops near the reattachment point, preventing the continuation of the solution
beyond θ*0. Instead we find that the numerical solution agrees with Neiland's (1970)
theory of reattachment, which does not involve any restriction upon the ramp angle.
The Master and the Maharajas: The Sikh Princes and the East Punjab Massacres of 1947
Authors: Copland Ian 
Published: September 2002

EventDuring the spring, summer and autumn of 1947 India's richest province, the Punjab, played host to a massive human catastrophe. The trigger for the catastrophe was Britain's parting gift to its Indian subjects of partition. Confronted by a seemingly intractable demand by the All-India Muslim League for a separate Muslim homeland—Pakistan—a campaign which since 1946 had turned increasingly violent, the British government early in 1947 accepted viceroy Lord Mountbatten's advice that partition was necessary to arrest the country's descent into civil war. ‘Mahatma’ Gandhi notably excepted, the leadership of the Congress party came gradually and reluctantly to the same conclusion. Sardar Vallabhbhai Patel, Jawaharlal Nehru's deputy, likened it to the cutting off of a diseased limb. But in accepting the ‘logic’ of the League's ‘two-nation’ theory, the British applied it remorselessly. They insisted that partition would have to follow the lines of religious affiliation, not the boundaries of provinces. In 1947 League president Muhammad Ali Jinnah was forced to accept what he had contemptuously dismissed in 1944 as a ‘moth-eaten’ Pakistan, a Pakistan bereft of something like half of Bengal and the Punjab and most of Assam.
Characterization of a Novel Lipoxygenase-Independent Senescence Mechanism in Alstroemeria peruviana Floral Tissue
Authors: Leverentz Michael K. , Wagstaff Carol , Rogers Hilary J. , Stead Anthony D. , Chanasut Usawadee , Silkowski Helena , Thomas Brian , Weichert Heiko , Feussner Ivo , Griffiths Gareth 
Published: September 2002

Abstract
The role of lipoxygenase (lox) in senescence ofAlstroemeria peruviana flowers was investigated using a combination of in vitro assays and chemical profiling of the lipid oxidation products generated. Phospholipids and galactolipids were extensively degraded during senescence in both sepals and petals and the ratio of saturated/unsaturated fatty acids increased. Lox protein levels and enzymatic activity declined markedly after flower opening. Stereochemical analysis of lox products showed that 13-lox was the major activity present in both floral tissues and high levels of 13-keto fatty acids were also synthesized. Lipid hydroperoxides accumulated in sepals, but not in petals, and sepals also had a higher chlorophyll to carotenoid ratio that favors photooxidation of lipids. Loss of membrane semipermeability was coincident for both tissue types and was chronologically separated from lox activity that had declined by over 80% at the onset of electrolyte leakage. Thus, loss of membrane function was not related to lox activity or accumulation of lipid hydroperoxides per se and differs in these respects from other ethylene-insensitive floral tissues representing a novel pattern of flower senescence.
Differential Expression of a Metallothionein Gene during the Presymbiotic versus the Symbiotic Phase of an Arbuscular Mycorrhizal Fungus
Authors: Lanfranco Luisa , Bolchi Angelo , Ros Emanuele Cesale , Ottonello Simone , Bonfante Paola 
Published: September 2002

AbstractA full-length cDNA encoding a metallothionein (MT)-like polypeptide, designated GmarMT1, was identified in an expressed sequence tag collection from germinated spores of the arbuscular mycorrhizal fungus Gigaspora margarita(BEG34). The GmarMT1 gene is composed of two exons separated by an 81-bp intron. It codes for a 65-amino acid polypeptide comprising a plant type 1 MT-like N-terminal domain and a C-terminal domain that is most closely related to an as-yet-uncharacterized fungal MT. As revealed by heterologous complementation assays in yeast,GmarMT1 encodes a functional polypeptide capable of conferring increased tolerance against Cd and Cu. TheGmarMT1 RNA is expressed in both presymbiotic spores and symbiotic mycelia, even in the absence of metal exposure, but is significantly less abundant in the latter stage. An opposite pattern was observed upon Cu exposure, which up-regulatedGmarMT1 expression in symbiotic mycelia but not in germinated spores. Together, these data provide the first evidence, to our knowledge, for the occurrence in an arbuscular mycorrhizal fungus of a structurally novel MT that is modulated in a metal and life cycle stage-dependent manner and may afford protection against heavy metals (and other types of stress) to both partners of the endomycorrhizal symbiosis.
Loss of Nuclear Gene Expression during the Phytochrome A-Mediated Far-Red Block of Greening Response
Authors: McCormac Alex C. , Terry Matthew J. 
Published: September 2002

Abstract
We have examined the expression of the HEMA1 gene, which encodes the key chlorophyll synthesis enzyme glutamyl-tRNA reductase, during the phytochrome A-mediated far-red light (FR) block of greening response in Arabidopsis. Our results demonstrate that the FR block of greening comprises two separate responses: a white light (WL) intensity-independent response that requires 3 d of FR and is associated with a loss of expression of the nuclear genesHEMA1 and Lhcb following the transfer to WL (transcriptionally coupled response) and a WL intensity-dependent response that is induced by 1 d of FR and is transcriptionally uncoupled. Both responses required phytochrome A. The transcriptionally uncoupled response correlated with a deregulation of tetrapyrrole synthesis and potential photooxidative damage and was inhibited by cytokinin. The transcriptionally coupled FR response was additive with the loss of expression following Norflurazon-induced photobleaching and was absent in the presence of sucrose or after lower fluence rate (1 μmol m−2 s−1) FR treatments. Both pathways leading to the loss of nuclear gene expression were inhibited by overexpression of NADPH:protochlorophyllide oxidoreductase, indicating a role for plastid signaling in the FR-mediated pathway. The significance of identifying a distinct phytochrome A-mediated plastid signaling pathway is discussed.
Plasmalemma Abscisic Acid Perception Leads to RAB18Expression via Phospholipase D Activation in Arabidopsis Suspension Cells
Authors: Hallouin Matthieu , Ghelis Thanos , Brault Mathias , Bardat Françoise , Cornel Daniel , Miginiac Emile , Rona Jean-Pierre , Sotta Bruno , Jeannette Emmanuelle 
Published: September 2002

Abstract
Abscisic acid (ABA) plays a key role in the control of stomatal aperture by regulating ion channel activities and water exchanges across the plasma membrane of guard cells. Changes in cytoplasmic calcium content and activation of anion and outward-rectifying K+ channels are among the earliest cellular responses to ABA in guard cells. In Arabidopsis suspension cells, we have demonstrated that outer plasmalemma perception of ABA triggered similar early events. Furthermore, a Ca2+influx and the activation of anion channels are part of the ABA-signaling pathway leading to the specific expression ofRAB18. Here, we determine whether phospholipases are involved in ABA-induced RAB18 expression. Phospholipase C is not implicated in this ABA pathway. Using a transphosphatidylation reaction, we show that ABA plasmalemma perception results in a transient stimulation of phospholipase D (PLD) activity, which is necessary for RAB18 expression. Further experiments showed that PLD activation was unlikely to be regulated by heterotrimeric G proteins. We also observed that ABA-dependent stimulation of PLD was necessary for the activation of plasma anion current. However, when ABA activation of plasma anion channels was inhibited, the ABA-dependent activation of PLD was unchanged. Thus, we conclude that in Arabidopsis suspension cells, ABA stimulation of PLD acts upstream from anion channels in the transduction pathway leading to RAB18 expression.
Sterol C-24 Methyltransferase Type 1 Controls the Flux of Carbon into Sterol Biosynthesis in Tobacco Seed
Authors: Holmberg Niklas , Harker Mark , Gibbard Carl L. , Wallace Andrew D. , Clayton John C. , Rawlins Sally , Hellyer Amanda , Safford Richard 
Published: September 2002

Abstract
The first committed step in the conversion of cycloartenol into Δ5 C24-alkyl sterols in plants is catalyzed by anS-adenosyl-methionine-dependent sterol-C24-methyltransferase type 1 (SMT1). We report the consequences of overexpressing SMT1 in tobacco (Nicotiana tabacum), under control of either the constitutive carnation etched ring virus promoter or the seed-specific Brassica napusacyl-carrier protein promoter, on sterol biosynthesis in seed tissue. Overexpression of SMT1 with either promoter increased the amount of total sterols in seed tissue by up to 44%. The sterol composition was also perturbed with levels of sitosterol increased by up to 50% and levels of isofucosterol and campesterol increased by up to 80%, whereas levels of cycloartenol and cholesterol were decreased by up to 53% and 34%, respectively. Concomitant with the enhanced SMT1 activity was an increase in endogenous 3-hydroxy-3-methylglutaryl coenzyme A reductase activity, from which one can speculate that reduced levels of cycloartenol feed back to up-regulate 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and thereby control the carbon flux into sterol biosynthesis. This potential regulatory role of SMT1 in seed sterol biosynthesis is discussed.