bluuebunny/crossref_metadata_2025 huggingface dataset:
Component PP3 from bovine milk is a substrate for
transglutaminase. Sequence location of putative crosslinking sites
Authors: SØRENSEN ESBEN S. , RASMUSSEN LONE K. , PETERSEN TORBEN E.
Published: July 2002

As the demands for food products of high quality increase, it will
become more
important to be able to modify the properties of food proteins. One possibility
is to
use enzymic modifications to improve functional properties and nutritional
values.
A highly efficient class of enzymic crosslinkers are transglutaminases
(TG, EC
2.3.2.13), calcium-dependent enzymes that catalyse an acyl transfer reaction
between protein-bound glutaminyl residues and primary amines (for review,
see
Aeschlimann & Paulsson, 1994). When protein-bound lysyl residues act
as acyl
acceptors, the reaction leads to the formation of intramolecular and/or
intermolecular
isopeptide bonds. Although a wide variety of amines such as putrescine,
cadaverine or lysyl residues may act as amine donors in this reaction,
only a limited
number of glutamine residues in certain proteins will act as amine acceptors
(Gorman
& Folk, 1980).

Ikura et al. (1981, 1985) reported that TG can be used to introduce
methionine
into casein and soyabean proteins and lysine into wheat gluten, thereby
showing that
TG can also be utilized to improve the nutritional value of food proteins.
There have
been a number of reports concerning the TG-mediated polymerization of food
proteins such as α-lactalbumin and β-lactoglobulin (Aboumahmoud
& Savello, 1990;
Færgemand et al. 1997), soyabean proteins and casein components
(Ikura et al.
1980a, b) and pea legumin (Larré et al.
1993). Recently, improved protein foaming
capacity and stability have been demonstrated in TG-catalysed polymers
of
soyabean protein and whey protein isolate (Yildirim et al. 1996).

Bovine PP3 (for review, see Girardet & Linden, 1996) is a phosphorylated
glycoprotein isolated from the proteose peptone fraction of milk (Sørensen
&
Petersen, 1993a). The primary structure of PP3 has been determined
(Sørensen &
Petersen, 1993b) and comprises a polypeptide backbone of 135 amino
acid residues
containing five phosphorylated serines, two threonine-linked O-glycosylations,
and
one N-glycosylation. Immunological studies have shown that PP3 is present
in the
milk fat globule membrane, and that PP3 forms multimeric aggregates in
bovine
milk (Sørensen et al. 1997). Several functions have been
suggested and investigated
for bovine PP3 and fractions enriched with PP3, including emulsification
(Shimizu
et al. 1989), inhibition of lipolysis (Girardet et al.
1993) and mitogenesis (Mati et al.
1993).

Previously, we have localized the potential TG-reactive glutamines in
the four
bovine caseins (Christensen et al. 1996) and in milk osteopontin
(Sørensen et al. 1994).
In the present study we have shown that component PP3 is a substrate for
guinea-pig liver TG containing both reactive glutamine and lysine residues. In
addition,
we have localized the glutamine residues that act as amine acceptors.
Heterogeneity of cationic amino acid transport systems in mouse
mammary gland and their regulation by lactogenic hormones
Authors: SHARMA REKHA , KANSAL VINOD K.
Published: July 2002

The mechanism of cationic amino acid transport in lactating mouse
mammary gland was investigated. Two Na+-independent systems of arginine
transport were discriminated on the basis of their sensitivity to leucine. The leucine-sensitive uptake of arginine (Km 0·4 mM)
was through a broad specificity system that
interacted with both cationic and neutral amino acids, and was inhibited by
preloading mammary tissue with neutral amino acids. The leucine-insensitive uptake
was identified as the y+ system (Km 0·76 mM).
Preloading mammary tissue with cationic amino acids increased the uptake of arginine by the
y+ system. Decreasing the pH of the external medium to 6·0
suppressed the y+ system-mediated uptake by
∼25%, whereas the broad specificity system remained unaffected. Lactogenic
hormones upregulated the y+ system-mediated uptake of arginine in pregnant mouse
mammary tissue cultured in vitro, although the broad specificity system remained
unaffected. The y+ system-mediated uptake increased 2-fold with insulin alone and
4-fold with the combination of insulin, cortisol and prolactin.
The Original Condemnation of Asian Montanism
Authors: STEWART-SYKES ALISTAIR
Published: July 2002

The object of this article is to describe the social and theological

setting of primitive Montanism within second-century Asia in
order to account for its appearance and its subsequent condemnation.
According to an anonymous source employed by Eusebius the
prophecy appeared in the middle of the second century under the
leadership of a recent convert called Montanus, and the faithful of Asia

gathered and condemned the movement at its outset. Clearly this is a
propagandist account but we may accept its broad outlines none the less,

in that there was a prophetic movement in which Montanus was a prime
mover, and which failed to receive acceptance in the wider Asian
Church.

It should be made clear that this article restricts itself to the earliest

period of the prophecy and therefore to primary sources which are
directly germane to that period. These sources are both preserved by
Eusebius, and consist of an unnamed writer known as the anonymous,
and an otherwise unknown Apollonius. A further possibly ancient source

is employed by Epiphanius, but we shall observe below that its
understanding of prophecy is hardly consistent with a second-century
Asian origin, whereas both the anonymous and Apollonius reveal their
Asian provenance in their extant writings. Although there is a degree of

bias in the presentation of the charges, we should none the less accept
that
there is a factual basis behind the assertions of the opponents, and that

their opposition was motivated by a genuine belief that the prophecy did

not conform with the tradition and the succession of the Church.
Sound sources in the interactions of two inviscid two-dimensional vortex pairs
Authors: TANG S. K. , KO N. W. M.
Published: July 2002

The sources of sound during the interactions of two identical two-dimensional inviscid
vortex pairs are investigated numerically by using the vortex sound theory and the
method of contour dynamics. The sound sources are identified and then separated
into two independent components, which represent the contributions from the vortex
centroid dynamics and the microscopic vortex core dynamics. Results show that the
sound generation mechanism of the latter is independent of the type of vortex pair
interaction, while that of the former depends on the jerks, accelerations and vortex
forces on the vortex pairs. The power developed by the vortex forces is found to be
important in the generation of sound when the vortex cores are severely deformed
and their centroids are close to each other. The isolated source terms also explain the
appearance of wavy oscillations on the time variations of the sound source strengths
in the vortex ring and the two-dimensional vortex interaction systems.
On Stokes flow in a semi-infinite wedge
Authors: SHANKAR P. N.
Published: July 2002

Consider Stokes flow in the semi-infinite wedge bounded by the sidewalls ϕ = ±α
and the endwall z = 0. Viscous fluid fills the region 0 < r < ∞,
0 < z < ∞ bounded by these planes; the motion of the fluid is driven by boundary data given on the
endwall z = 0. A consequence of the linearity of the problem is that one can treat
the velocity field q(r, ϕ, z) as the sum of a field
qa(r, ϕ, z) antisymmetric in ϕ and one symmetric in it,
qs(r, ϕ, z). It is shown in each of these cases that there exists a real
vector eigenfunction sequence vn(r, ϕ, z) and a complex vector eigenfunction sequence
un(r, ϕ, z), each member of which satisfies the sidewall no-slip condition and has a
z-behaviour of the form e−kz. It is then shown that one can, for each case, write down
a formal representation for the velocity field as an infinite integral over k of the sums
of the real and complex eigenfunctions, each multiplied by unknown real and complex
scalar functions bn(k) and an(k),
respectively, that have to be determined from the
endwall boundary conditions. A method of doing this using Laguerre functions and
least squares is developed. Flow fields deduced by this method for given boundary
data show interesting vortical structures. Assuming that the set of eigenfunctions is
complete and that the relevant series are convergent and that they converge to the
boundary data, it is shown that, in general, there is an infinite sequence of corner
eddies in the neighbourhood of the edge r = 0 in the antisymmetric case but not in
the symmetric case. The same conclusion was reached earlier for the infinite wedge by
Sano & Hasimoto (1980) and Moffatt & Mak (1999). A difficulty in the symmetric case
when 2α = π/2, caused by the merger of two real eigenfunctions, has yet to be resolved.
Finite-amplitude internal wavepacket dispersion and breaking
Authors: SUTHERLAND BRUCE R.
Published: July 2002

The evolution and stability of two-dimensional, large-amplitude, non-hydrostatic
internal wavepackets are examined analytically and by numerical simulations. The
weakly nonlinear dispersion relation for horizontally periodic, vertically compact
internal waves is derived and the results are applied to assess the stability of weakly
nonlinear wavepackets to vertical modulations. In terms of Θ, the angle that lines of
constant phase make with the vertical, the wavepackets are predicted to be unstable
if [mid ]Θ[mid ] < Θc, where
Θc = cos−1 (2/3)1/2 ≃ 35.3°
is the angle corresponding to internal
waves with the fastest vertical group velocity. Fully nonlinear numerical simulations of
finite-amplitude wavepackets confirm this prediction: the amplitude of wavepackets
with [mid ]Θ[mid ] > Θc decreases over time; the amplitude of wavepackets with
[mid ]Θ[mid ] < Θc
increases initially, but then decreases as the wavepacket subdivides into a wave train,
following the well-known Fermi–Pasta–Ulam recurrence phenomenon.

If the initial wavepacket is of sufficiently large amplitude, it becomes unstable
in the sense that eventually it convectively overturns. Two new analytic conditions
for the stability of quasi-plane large-amplitude internal waves are proposed. These
are qualitatively and quantitatively different from the parametric instability of plane
periodic internal waves. The ‘breaking condition’ requires not only that the wave
is statically unstable but that the convective instability growth rate is greater than
the frequency of the waves. The critical amplitude for breaking to occur is found
to be ACV = cot Θ (1 + cos2 Θ)/2π,
where ACV is the ratio of the maximum vertical
displacement of the wave to its horizontal wavelength. A second instability condition
proposes that a statically stable wavepacket may evolve so that it becomes convectively
unstable due to resonant interactions between the waves and the wave-induced
mean flow. This hypothesis is based on the assumption that the resonant long
wave–short wave interaction, which Grimshaw (1977) has shown amplifies the waves
linearly in time, continues to amplify the waves in the fully nonlinear regime. Using
linear theory estimates, the critical amplitude for instability is
ASA = sin 2Θ/(8π2)1/2.
The results of numerical simulations of horizontally periodic, vertically compact
wavepackets show excellent agreement with this latter stability condition. However,
for wavepackets with horizontal extent comparable with the horizontal wavelength,
the wavepacket is found to be stable at larger amplitudes than predicted if Θ [lsim ] 45°. It
is proposed that these results may explain why internal waves generated by turbulence
in laboratory experiments are often observed to be excited within a narrow frequency
band corresponding to Θ less than approximately 45°.
Bubble dispersion and interphase coupling in a free-shear flow
Authors: RIGHTLEY P. M. , LASHERAS J. C.
Published: July 2002

The interaction of a dilute dispersed cloud of microbubbles with a planar free-shear
layer is investigated experimentally. The emphasis of this study is on the role of the
coherent large scales of the flow in the bubble dispersion field and the energy redistribution
within the carrier phase. The interphase momentum transfer integrals that
appear in the volume-averaged momentum and energy equations account for redistribution
of energy from potential to kinetic within the carrier phase. This results from
both the hydrostatic and dynamic pressure fields. The energy redistribution within the
carrier phase that is associated with the large-scale structures of the flow possesses
significant inhomogeneities within the mixing layer. Peaks of enhanced kinetic energy
generation are associated with the upwelling regions at the downstream edge of the
coherent vortex cores, and weaker peaks of kinetic energy destruction are associated
with downwelling regions. The contribution of the quasi-steady drag term to the total
energy redistribution is found to be dominant in only a limited region of the flow field.
Circulation around a thin zonal island
Authors: WELLS J. R. , HELFRICH K. R.
Published: July 2002

Laboratory and numerical experiments are used to study flow of a uniform-density
fluid on the β-plane around a thin zonally elongated island (or ridge segment in
the abyss). This orientation is chosen specifically to highlight the roles of the zonal
boundary layer dynamics in controlling the circulation around the island. There are
examples of deep ocean topography that fall into this category which make the work
directly applicable to oceanic flows. Linear theory for the transport around the island
and the flow structure is based on a modification of the Island Rule (Pedlosky et
al. 1997; Pratt & Pedlosky 1999). The linear solution gives a north–south symmetric
flow around the island with novel features, including stagnation points which divide
the zonal boundary layers into eastward and westward flowing zones, and a western
boundary layer of vanishing length, and zonal jets. Laboratory experiments agree
with the linear theory for small degrees of nonlinearity, as measured by the ratio of
the inertial to Munk boundary layer scales. With increasing nonlinearity the north–south
symmetry is broken. The southern stagnation point (for anticyclonic forcing)
moves to the eastern tip of the island. The flow rounding the eastern tip from the
northern side of the island now separates from the island. Time-dependence emerges
and recirculation cells develop on the northern side of the island. Mean transport
around the island is relatively unaffected by nonlinearity and given to within 20% by
the modified Island Rule. Numerical solutions of the shallow water equations are in
close agreement with the laboratory results. The transition from zonal to meridional
island orientation occurs for island inclinations from zonal greater than about 20°.
Feedback control of weakly nonlinear Rayleigh–Bénard–Marangoni convection
Authors: OR A. C. , KELLY R. E.
Published: July 2002

We study the effect of proportional feedback control on the onset and development
of finite-wavelength Rayleigh–Bénard–Marangoni (RBM) convection using weakly
nonlinear theory as applied to Nield's model, which includes both thermocapillarity
and buoyancy but ignores deformation of the free surface. A two-layer model configuration
is used, which has a purely conducting gas layer on top of the liquid. In the
feedback control analysis, a control action in the form of temperature or heat flux
is considered. Both measurement and control action are assumed to be continuous
in space and time. Besides demonstrating that stabilization of the basic state can
be achieved on a linear basis, the results also indicate that a wide range of weakly
nonlinear flow properties can also be altered by the linear and nonlinear control
processes used here. These include changing the nature of hexagonal convection and
the amount of subcritical hysteresis associated with subcritical bifurcation.
Stationary fronts of the thermohaline circulation

in the low-aspect-ratio limit
Authors: FLEURY LAURENCE , THUAL OLIVIER
Published: July 2002

A two-dimensional Boussinesq model of the thermohaline convection

in a rectangular

domain is forced at the top by a prescribed temperature and a prescribed
salinity

flux. The two forcings have opposite effects on the density field, which
leads to the

formation of fronts and multiple equilibria. Numerical results

are interpreted through

a comparison with the solutions of an asymptotic equation, derived in the
limit of a

shallow basin by Cessi & Young (1992). In order to

explain the discrepancies between

the numerical and the asymptotic solutions, we extend this asymptotic approach

through a geometrical representation and a topological classification of
the surface

forcings. By comparing three forcings, we propose a global picture which
gives clues

to interpret the numerical solutions.
Stratification-induced lateral dispersion of a density anomaly
Authors: SMITH RONALD
Published: July 2002

When a small amount of marked solute is released into a stratified

fluid, there is

lateral dispersion of the marked solute and a larger lateral dispersion
of

any density

anomaly. The method of moments is used to calculate the two dispersion
coefficients.

The excess dispersion for the density is shown to be proportional to the
fractional

density decrease from the bed to the free surface and to the cube of the
water depth,

and inversely proportional to the vertical mixing for lateral momentum.
For weak

turbulent mixing the stratification-induced lateral dispersion

for the density anomaly

can be several orders of magnitude greater than the lateral turbulent mixing
for

marked solute
On the steady streaming flow due to

high-frequency vibration in nearly inviscid liquid bridges
Authors: NICOLÁS JOSÉ A. , RIVAS DAMIÁN , VEGA JOSÉ M.
Published: July 2002

The steady streaming flow due to vibration in capillary

bridges is considered in the

limiting case when both the capillary Reynolds number and the

non-dimensional

vibration frequency (based on the capillary time) are large. An

asymptotic model is

obtained that provides the streaming flow in the bulk, outside the

thin oscillatory boundary layers near the disks and the interface. Numerical

integration of this

model shows that several symmetric and non-symmetric streaming

flow patterns are obtained for varying values of the vibration parameters.

As a by-product, the

quantitative response of the liquid bridge to high-frequency

axial vibrations of the disks is also obtained.
Lubricated plane slider bearing: solution of the inlet problem with

upstream free surface
Authors: MALVANO R. , VATTA F.
Published: July 2002

The present work studies the problem of the flow field around the
inlet section in the
case of a plane slider bearing with upstream free surface. In order to
determine the
pressure head build-up, the inlet region of the bearing can be studied
by considering
a rigid plane sheet (pad) parallel to a plane wall (guide) which slides
at a steady speed
in a viscous incompressible fluid. The mathematical model described is
based on the
application of the theory of analytic functions. Through Dini's equation,
which relates
the real and the complex part of any analytic function, defined on the
boundary of
a domain, it is possible to determine the distribution of pressure on this
boundary
and the geometry of the free surface. In this way the problem is formally
solved;
however, it is difficult to obtain the solution because the thickness of
the free surface
is unknown. It would be possible to adopt an iterative method but the great
difficulty
associated with this method of solution induced the authors to follow a
simplified
technique. Through this study it was possible to determine the pressure
build-up at
the inlet; this quantity is the essential boundary condition to evaluate
the actual load
capacity of a slider bearing.
The evolution of a perturbed vortex in a pipe to
axisymmetric vortex breakdown
Authors: RUSAK Z. , WANG S. , WHITING C. H.
Published: July 2002

The evolution of a perturbed vortex in a pipe to axisymmetric vortex
breakdown
is studied through numerical computations. These unique simulations are
guided
by a recent rigorous theory on this subject presented by Wang & Rusak
(1997a).
Using the unsteady and axisymmetric Euler equations, the nonlinear dynamics
of
both small- and large-amplitude disturbances in a swirling flow are described
and
the transition to axisymmetric breakdown is demonstrated. The simulations
clarify
the relation between our linear stability analyses of swirling flows (Wang
& Rusak
1996a, b) and the time-asymptotic behaviour of the
flow as described by steady-state
solutions of the problem presented in Wang & Rusak (1997a).
The numerical
calculations support the theoretical predictions and shed light on the
mechanism
leading to the breakdown process in swirling flows. It has also been demonstrated

that the fundamental characteristics which lead to vortex instability and
breakdown
in high-Reynolds-number flows may be calculated from considerations of
a single,
reduced-order, nonlinear ordinary differential equation, representing a
columnar flow
problem. Necessary and sufficient criteria for the onset of vortex breakdown
in a
Burgers vortex are presented.
Faraday's instability in viscous fluid
Authors: CERDA E. A. , TIRAPEGUI E. L.
Published: July 2002

We find a quantitative approximation which explains the appearance
and amplification
of surface waves in a highly viscous fluid when it is subjected to vertical
accelerations
(Faraday's instability). Although stationary surface waves with frequency
equal to
half of the frequency of the excitation are observed in fluids of different
kinematical
viscosities we show here that the mechanism which produces the instability
is very
different for a highly viscous fluid as compared with a weakly viscous
fluid. This is
achieved by deriving an exact equation for the linear evolution of the
surface which
is non-local in time. We show that for a highly viscous fluid this equation
becomes
local and of second order and is then a Mathieu equation which is different
from
the one found for weak viscosity. Analysing the new equation we find an
intimate
relation with the Rayleigh–Taylor instability.
Secondary flow in a Hele-Shaw cell
Authors: BALSA THOMAS F.
Published: July 2002

We examine the flow in a horizontal Hele-Shaw cell in which the
undisturbed
unidirectional flow at infinity is required to stream around a vertical
cylinder spanning
the gap between the two (horizontal) plates of the cell. A combination
of matched
asymptotic expansions and numerical methods is employed to elucidate the
structure
of the boundary layer near the surface of the cylinder. The two length
scales of the
problem are the gap, h, and the length of the body, l;

it is assumed that h/l<<1. The
characteristic Reynolds number based on l is O(1).
The length scales associated with
the boundary layer and the classical Hele-Shaw flow pattern are
O(h) and O(l), respectively.

It is found that the boundary layer contains streamwise vorticity. This
vorticity is
generated at the three no-slip surfaces (the two plates and the cylinder
wall) as a result
of the cross-flow induced by the streamwise acceleration/deceleration
of the flow
around the curved cylinder. The strength of the secondary flow, hence the
associated
streamwise vorticity, is proportional to changes in body curvature. The
validity of the
classical Hele-Shaw flow is examined systematically, and higher-order corrections
are
worked out. This results in a displacement thickness that is roughly 30%
of the gap.
In other words, the lowest-order correction to the classical Hele-Shaw
flow may be
obtained by requiring the outer flow (on the scale O(l))

to satisfy the no-penetration
boundary condition on a displaced cylinder surface. The boundary layer
contains
‘corner’ vortices at the intersections of the horizontal
plates and the vertical cylinder surface.
A note on the optimum profile of a sprayless planing surface
Authors: MAKLAKOV DMITRI V.
Published: July 2002

The paper presents an exact analytical solution to the problem
of finding the optimum
profile of a two-dimensional plate which planes on a water surface without
spray
formation and maximizes the lift force. The lift is maximized under the
only isoperimetric
constraint of fixed total arclength of the plate. The exact solution is
compared
with approximate analytical and numerical results by Wu & Whitney (1972).
The
shape of the optimum plate turns out to be technically unrealizable because
of small,
tightly wound spirals near the end points. It was shown numerically that
cutting off
small segments near the end points leads on the one hand to insignificant
change in
the lift force and on the other hand to a non-separating boundary layer
along the
remaining part of the optimum plate.
On cusped interfaces
Authors: SHIKHMURZAEV YULII D.
Published: July 2002

An asymptotic analysis of two-dimensional free-surface cusps associated
with flows
at low Reynolds numbers is presented on the basis of a model which, in
agreement
with direct experimental observations, considers this phenomenon as a particular

case of an interface formation–disappearance process. The model was
derived from
first principles and earlier applied to another similar process: the moving
contact-line
problem. As is shown, the capillary force acting on a cusp from the free
surface, which
in the classical approach can be balanced by viscous stresses only if the
associated
rate of dissipation of energy is infinite, in the present theory is always
balanced by the
force from the surface-tension-relaxation ‘tail’,
which stretches from the cusp towards
the interior of the fluid. The flow field near the cusp is shown to be
regular, and the
surface-tension gradient in the vicinity of the cusp, caused and maintained
by the
external flow, induces and is balanced by the shear stress. Existing approaches
to the
free-surface cusp description and some relevant experimental aspects of
the problem
are discussed.
The growth, saturation, and scaling behaviour of
one- and two-dimensional disturbances in fluidized beds
Authors: GÖZ M. F. , SUNDARESAN S.
Published: July 2002

It is well-known that fluidized beds are usually unstable to small
perturbations and
that this leads to the primary bifurcation of vertically travelling plane
wavetrains.
These one-dimensional periodic waves have been shown recently to be unstable
to
two-dimensional perturbations of large transverse wavelength in gas-fluidized
beds.
Here, this result is generalized to include liquid-fluidized beds and to
compare typical
beds fluidized with either air or water. It is shown that the instability
mechanism
remains the same but there are big differences in the ratio of the primary
and
secondary growth rates in the two cases. The tendency is that the secondary
growth
rates, scaled with the amplitude of a fully developed plane wave, are of
similar
magnitude for both gas- and liquid-fluidized beds, while the primary growth
rate
is much larger in the gas-fluidized bed. This means that the secondary
instability
is accordingly stronger than the primary instability in the liquid-fluidized
bed, and
consequently sets in at a much smaller amplitude of the primary wave. However,

since the waves in the liquid-fluidized bed develop on a larger time and
length scale,
the primary perturbations need longer time and thereby travel farther until
they
reach the critical amplitude. Which patterns are more amenable to being
visually
recognized depends on the magnitude of the initially imposed disturbance
and the
dimensions of the apparatus. This difference in scale plays a key role
in bringing
about the differences between gas- and liquid-fluidized beds; it is produced
mainly by
the different values of the Froude number.
Direct numerical simulations of bubbly flows

Part 2. Moderate Reynolds number arrays
Authors: ESMAEELI ASGHAR , TRYGGVASON GRÉTAR
Published: July 2002

Direct numerical simulations of the motion of two- and three-dimensional finite

Reynolds number buoyant bubbles in a periodic domain are presented. The full

Navier–Stokes equations are solved by a finite difference/front tracking method that

allows a fully deformable interface between the bubbles and the ambient fluid and

the inclusion of surface tension. The rise Reynolds numbers are around 20–30 for the

lowest volume fraction, but decrease as the volume fraction is increased. The rise of

a regular array of bubbles, where the relative positions of the bubbles are fixed, is

compared with the evolution of a freely evolving array. Generally, the freely evolving

array rises slower than the regular one, in contrast to what has been found earlier for

low Reynolds number arrays. The structure of the bubble distribution is examined

and it is found that while the three-dimensional bubbles show a tendency to line up

horizontally, the two-dimensional bubbles are nearly randomly distributed. The effect

of the number of bubbles in each period is examined for the two-dimensional system

and it is found that although the rise Reynolds number is nearly independent of

the number of bubbles, the velocity fluctuations in the liquid (the Reynolds stresses)

increase with the size of the system. While some aspects of the fully three-dimensional

flows, such as the reduction in the rise velocity, are predicted by results for two-dimensional bubbles, the structure of the bubble distribution is not. The magnitude

of the Reynolds stresses is also greatly over-predicted by the two-dimensional results.
Flow regimes in a wide ‘sliced-cylinder’ model of
homogeneous beta-plane circulation
Authors: GRIFFITHS ROSS W. , KISS ANDREW E.
Published: July 2002

We report new experiments with the ‘sliced-cylinder’
β-plane model of Pedlosky &
Greenspan (1967) and Beardsley (1969), but with a much wider basin such that the
western boundary current and its eddies occupy a small fraction of the basin width.
These experiments provide new insights into nonlinear aspects of the flow: the critical
conditions for boundary current separation and the transition from stable to unstable
flow are redefined, and a further transition from periodic to chaotic eddy shedding
under strong anticyclonic forcing is also found. In the nonlinear regimes the western
boundary current separates from the western wall and shoots into the interior as a
narrow jet that undergoes a rapid adjustment to join with the broad slow interior
flow. In the unstable regimes this adjustment involves eddy shedding. Each transition
occurs at a fixed critical value of a Reynolds number Reγ
based on the velocity and width scales for a purely viscous boundary current:
the flow is unstable for Reγ > 123±4 and
aperiodic for Reγ > 231±5.
The results provide evidence that the
mechanism causing instability is shear in the separated jet rather than the breaking of
a large-amplitude Rossby wave. A quasi-geostrophic numerical model applied to the
laboratory conditions yields a stability boundary and detailed characteristics of the
flow largely consistent with those determined from the experiments. It also reveals a
strong dependence of the circulation pattern on basin aspect ratio, and shows that an
adverse higher-order pressure gradient is responsible for western boundary current
separation in this model. Eddy–eddy interactions and feedback of fluctuations from
the eddy formation region to upstream parts of the boundary current contribute to
aperiodic behaviour. As a result of eddy shedding, passive tracer from each streamline
in the boundary current can be stirred across much of the width of the basin.
Suppression of vertical diffusion in strongly stratified turbulence
Authors: KANEDA YUKIO , ISHIDA TAKAKI
Published: July 2002

A spectral approximation for diffusion of passive scalar in stably and strongly
stratified turbulence is presented. The approximation is based on a linearized approximation
for the Eulerian two-time correlation and Corrsin's conjecture for the Lagrangian
two-time correlation. For strongly stratified turbulence, the vertical component of the
turbulent velocity field is well approximated by a collection of Fourier modes (waves)
each of which oscillates with a frequency depending on the direction of the wavevector.
The proposed approximation suggests that the phase mixing among the Fourier
modes having different frequencies causes the decay of the Lagrangian two-time vertical
velocity autocorrelation, and the highly oscillatory nature of these modes results
in the suppression of single-particle dispersion in the vertical direction. The approximation
is free from any ad hoc adjusting parameter and shows that the suppression
depends on the spectra of the velocity and fluctuating density fields. It is in good
agreement with direct numerical simulations for strongly stratified turbulence.
Embracing a Suitable Past: Independence Celebrations under
Mexico's Second Empire, 1864–6
Authors: DUNCAN ROBERT H.
Published: July 2002

This study examines Emperor Maximilian's efforts in using
public
rituals, patriotic symbolism, and the emblems of nationalism to devise
an
appropriate past for his Mexican empire. The ‘republican’ celebration
of
independence and its heroes formed the cornerstone of an effort to reconcile

feuding political factions, build social cohesion, and ultimately legitimate
his
regime. The article concentrates on the independence ceremonies, speeches,
and
statuary employed by the empire. Ultimately, the political dissension existing
in
Mexico could not be surmounted by symbols alone. Nevertheless, the attempt

reveals the creative use and limits of public rituals in the political
realm.
Between Brazil and Bahia: Celebrating
Dois de Julho in Nineteenth-Century
Salvador
Authors: KRAAY HENDRIK
Published: July 2002

Commemorating the expulsion of Portuguese troops from Salvador,
Bahia, on 2 July 1823, the Dois de Julho festival represented Bahian society
collectively and marked differences of national origin, class, and race. It
challenged the Brazilian state's official patriotism by articulating a regional
identity, and through its commemoration of the independence-era popular
mobilisation, presented a story of Brazil's origins that contradicted the official
patriotism which celebrated Emperor Pedro I as Brazil's founder. Dois de Julho's
popularity and durability, moreover, suggest a significant and socially-broad
engagement with the imperial state, which cannot be considered a remote and
alien entity to the urban population.
Training Policy and the Property
Rights of Labour in Chile (1990–1997):
Social Citizenship in the Atomised
Market Regime
Authors: HAAGH LOUISE
Published: July 2002

This article argues that the training and employment policies of Chile's
transition governments since 1990 have failed significantly to promote the
development of human resources and occupational citizenship, and identifies key
structural and political causes. In particular, the weak development of the
property rights of labour and of markets in skill are seen as enduring economic
and institutional legacies of the period of dictatorship which continue to constrain
key areas of economic development as well as social citizenship rights. The article
advocates an analysis of citizenship and skill development that identifies the
problem of institutional coordination between a range of different services in
labour markets. It suggests that the social organisation of skill markets in Chile
systematically discriminates against long-term investments in workers. Hence,
even in Chile where economic reformers have sought to maximise markets,
decisions on skill investments are, to an important degree, conditioned by power
relations and organisational inertia inside individual firms and, at the aggregate
level, by the selective channelling of information and the (unplanned) institutional
structuring of training supply.
Categories of the Noun Phrase in Jarawara
Authors: DIXON R. M. W.
Published: July 2002

The head of an NP is taken to be that component which determines the categories of
the NP as a whole. First impression of an NP in Jarawara (Arawá family, Brazil)
involving inalienable possession (e.g. o-mano ‘my arm’) is that there is conflict of
criteria concerning what is head. The gender of the NP, for verbal suffix agreement,
is determined by the possessor (here Isg prefix o-), suggesting that this should be
taken to be head. But the whole NP counts as 3rd person, for verbal prefix agreement,
suggesting that the possessed noun (mano ‘arm’) should be taken as head.
Furthermore, the NP counts as inanimate. Detailed analysis shows that there is in fact
no conflict. All NPs in this language are 3rd person (1st and 2nd persons being
confined to head marking within the predicate and functioning as possessors within
an NP, not as full NPs). And all NPs involving inalienable possession count as
inanimate. The only variable is gender, which is determined by the possessor; plainly,
this is the unequivocal head of the NP.
Structural change, the oil boom and the cocoa economy of
southwestern Nigeria, 1973–1980s
Authors: Walker Ezekiel Ayodele
Published: July 2002

The oil boom that lasted from the early 1970s until about 1983 spawned a
phenomenal expansion of the Nigerian economy. Within a few years, oil
revenues rose from 1·4 billion naira in 1973 to 12·86 billion naira by 1980.
The oil boom led to the assigning of substantial sums of money to the cocoa
industry of southwestern Nigeria. In spite of these investments, the cocoa
industry stagnated during the oil boom years. Using oral interviews and
archival documents, this paper examines structural change in the cocoa
industry before the oil boom, and analyses the failure of government rehabilitation
programmes during the oil boom years.
Stability analysis of the ideal m=n=1 kink
mode in toroidal geometry by direct
expansion of the hydromagnetic equations
Authors: WAHLBERG C. , BONDESON A.
Published: July 2002

The stability condition and growth rate of the ideal, internal
m=n=1 kink
mode in a toroidal plasma are calculated by means of a direct inverse-aspect-ratio expansion of the magnetohydrodynamic (MHD) equations, rather than
by
using the energy principle. The analysis is based on the use of computer-aided
algebra. The general equation for incompressible MHD oscillations in a
low-β
circular tokamak is derived to lowest order in the inverse aspect ratio.
This
derivation generalizes the Pfirsch-Schlüter factor for the kinetic
energy in
toroidal geometry.
E×B guiding-centre motion in three
electrostatic waves: statistics of separatrix crossings
Authors: WEYSSOW B.
Published: July 2002

E×B guiding-centre (GC) motion in a special

configuration of three low-frequency
electrostatic waves can be considered as a paradigmatic Hamiltonian system
for
studying adiabatic motion and separatrix crossings. A peculiarity of this
system is
that a single initial condition gives rise to two stroboscopic phase-space
trajectories.
According to the classical Hamiltonian theory, the proportion of points
on the
stroboscopic trajectories is a function of the time evolution of the surfaces
enclosed
by the separatrices in the phase space. This behaviour is qualitatively
observed in
test-particle numerical experiments. The ability of numerical integration
methods
like the ‘classical’ fourth-order Runge–Kutta integration

scheme or a third-order symplectic integrator to reproduce the statistics
is analysed.
Photoabsorption by an ion immersed in a
plasma at any temperature
Authors: ISHIKAWA K. , FELDERHOF B. U. , BLENSKI T. , CICHOCKI B.
Published: July 2002

The photoabsorption cross-section of an ion immersed in a plasma
is studied on
the basis of the Thomas–Fermi approximation for the equilibrium electron
distribution
and Bloch's classical hydrodynamic model for collective motion of
the
electrons. The frequency-dependent cross-section scales with the nuclear
charge,
and depends strongly on the plasma density and temperature. An approximation

of the frequency dependence is constructed with the aid of sum rules and
Padé
approximants.
Transport of intense LH pulses into a tokamak plasma
Authors: KRLÍN L. , KLÍMA R. , PAVLO P. , PETRŽÍLKA V. , SVOBODA V. , TATARONIS J. A.
Published: July 2002

Application of lower-hybrid (LH) power in short, intense pulses in the
5–10 GW range should overcome the limiting effects of Landau damping, and
thereby permit the penetration of LH power into the interior of large-scale plasmas.
We show that, under such very intense LH pulses, wave coupling may deteriorate
because of nonlinear density changes due to the ponderomotive force effects in front
of the grill. Ponderomotive forces are also likely to induce strong plasma bias and
consequent poloidal and toroidal plasma rotation. Although backward electric currents,
created in the plasma by intense LH pulses, dissipate a large portion of the
radio frequency power absorbed, the current drive efficiency is acceptable. We use
a numerical simulation of wave–particle interactions to analyse the applicability of
standard quasilinear theory to the case of large energy flux densities. The initial
results indicate the existence of important restrictions on the use of the quasilinear
approximation. The results of the present paper also indicate that some of the
effects considerably alter some ideas of Cohen et al.
Evidence of external digestion of crustaceans in Octopus vulgaris paralarvae
Authors: Hernández-García Vicente , Martín Ana Y. , Castro José J.
Published: July 2002

This paper reports, for the first time, the existence of external digestion of decapod larvae by the common octopus, Octopus vulgaris (Mollusca: Cephalopoda), paralarvae. Zoeae of three crab species were externally digested, leaving a whole and empty exoskeleton. The attack sequence on these prey is also described, and divided into the same three phases (attention, positioning and seizure) already known for Sepia hatchlings.
Host use pattern and life history of Liopetrolisthes mitra, a crab associate of the black sea urchin Tetrapygus niger
Authors: Baeza J.A. , Thiel M.
Published: July 2002

The porcellanid crab Liopetrolisthes mitra is a common associate of the black sea urchin, Tetrapygus niger in north central Chile. The host-use pattern, population dynamics and reproductive pattern of L. mitra on sea urchins were examined between January 1996 and February 1997. Each month, between 60 and 95 per cent of all collected urchins hosted crabs, with the highest frequency of cohabitation occurring during the austral summer (January to March). Group sizes of crabs on individual urchins ranged from 1 to 25 crabs per host. The average density of crabs on the urchins ranged from 2 to 5.5 crabs per host. Large urchins were inhabited by crabs more frequently than small urchins but urchin size had no effect on the number or size of crabs. The sex ratio of adult crabs was ˜1:1 during most months. Reproduction occurred throughout the year but was most intense during the austral spring and summer (October to March), when the highest percentage of ovigerous females were found. Similarly, recruitment of L. mitra occurred throughout the year but reached a peak during austral summer and early autumn (January to May). All life stages of L. mitra including recently settled megalopae and reproductive adults were found on urchins. Size–frequency analysis indicated that many crabs live >1.5 years. The results of this study confirm that the association between L. mitra and T. niger is strong and persists throughout the benthic life of the commensal crab.
The behaviour of Loligo opalescens (Mollusca: Cephalopoda) as observed by a remotely operated vehicle (ROV)
Authors: Hunt James C. , Zeidberg Louis D. , Hamner William M. , Robison Bruce H
Published: July 2002

The behaviour of Loligo opalescens as observed by a remotely operated vehicle (ROV) was analysed. Thirty-nine behavioural components were identified and classed into four categories: chromatic, postural, locomotory, and inking. The frequency with which components were expressed was correlated to whether or not an individual was schooling, shoaling, alone with the ROV, or in the presence of other species. Behaviours observed were compared to those reported for other Loligo species. Observations of schooling and feeding behaviour, and reactions to other species are included.
First record of the bryozoan genus Stylopoma from the Mediterranean Sea
Authors: Tilbrook Kevin J.
Published: July 2002

The first record of the genus Stylopoma (Bryozoa: Cheilostomatida) is reported from the Mediterranean Sea with the description of Stylopoma inchoans sp. nov. from a single specimen collected in the 19th Century. Its affinities to recently described Indo-Pacific species are discussed.
Diet and association of Pontonia pinnophylax occurring in Pinna nobilis: insights from stable isotope analysis
Authors: Kennedy H. , Richardson C.A. , Duarte C.M. , Kennedy D.P.
Published: July 2002

Stable carbon isotope measurements (δ13C) were used to assess the sources of carbon assimilated by the fan mussel Pinna nobilis, in sea grass Posidonia oceanica meadows, and an associated shrimp Pontonia pinnophylax which occurs within this bivalve's mantle cavity. The primary carbon sources available to both animals displayed a wide range of δ13C values, from −12·3 to −22·3‰. The δ13C and δ15N of Pinna nobilis and Pontonia pinnophylax suggest that they assimilate carbon from similar sources, occupy comparable trophic levels and that their association is commensal.
Summertime Diel Variations in the Diet Composition and Feeding Periodicity of Red Pandora (Pagellus erythrinus) in Hisarönü Bay
Authors: Benli H.A. , Kaya M. , Ünlüoĝlu A. , Kataĝan T. , Cihangir B.
Published: July 2002

In summer 1997, the stomach contents of 235 red pandora collected by bottom trawl from Hisarönü Bay in the southern Aegean coast of Turkey, were analysed. It was observed that red pandora is predominantly a diurnal feeder. More intensive feeding started in the afternoon, reaching its maximum value in the evening and continued until dusk. The minimum feeding intensity occurred during the night. The diet was found to consist primarily of polychaetes, especially Glyceridae, and crustaceans, mainly Natantia. No significant diel variation was observed in the diet composition of red pandora.
Mitochondrial DNA variation among open-sea and enclosed populations of the scallop Pecten maximus in western Britain
Authors: Heipel D.A. , Bishop J.D.D. , Brand A.R.
Published: July 2002

The great scallop Pecten maximus (Bivalvia: Pectinidae) supports a substantial European fishery with a recent history of declining catches caused by over-exploitation. The sustainable exploitation of shellfish populations requires knowledge of the extent to which commercial grounds are reproductively self-sustaining or supplied with larvae originating from further afield. The degree of genetic differentiation between locations can provide important indirect evidence, reflecting the pattern and scale of effective larval dispersal. Pecten maximus were sampled from five locations around the Isle of Man, from Mulroy Bay (Ireland) and from Plymouth. Restriction-site variation was investigated in two PCR-amplified mitochondrial DNA fragments of 2 and 3 kb, respectively. Haplotype and nucleotide diversity within populations, and nucleotide divergence between populations, were calculated. Mean nucleotide sequence divergence was corrected for within-population polymorphisms and visualized by UPGMA cluster diagrams. Molecular analysis of variance (AMOVA) was carried out. Results showed low levels of population differentiation. Slight but significant differentiation between Isle of Man populations was revealed, with East Douglas appearing distinct from the remaining Manx locations. The analyses also indicated the distinction of Mulroy Bay from the other populations, and the lowest genetic variability was recorded from this enclosed habitat. This probably reflects the relative isolation of Mulroy Bay, whereas dynamic hydrographic conditions in the Irish Sea and the Channel may generally ensure extensive mixing of the planktonic larvae.