bluuebunny/crossref_metadata_2025 huggingface dataset:
The Policeman as Worker: A Comparative Survey c. 1800–1940
Authors: Emsley Clive
Published: July 2002

In the exciting new social history of the 1960s the concept of class struggle tended to underpin much of the work on the working class in general, and on various labour groups in particular. Historians sought to find faces in crowds and to rescue others from “the enormous condescension of posterity”. The police, however, when they appeared in this history, were usually as nameless and faceless as the crowds had been previously. They were also commonly portrayed as oppressors, and even in the more perceptive and ground-breaking attempts to explore the police themselves, they were seen through the refracted lens of their working-class critics as “blue locusts” and as a bourgeois instrument for controlling a new society. Parallel research conducted at roughly the same time by sociologists, social psychologists and others developed theoretical perspectives based on two assumptions: first, that certain kinds of authoritarian personality were attracted to police careers, and second, that policing roles had predictable effects on the behaviour and personality of policemen. Subsequent research has suggested these assumptions to be largely unfounded, yet in this respect also, historical explorations of policemen as workers remain few.
THE POLITICS OF COMMERCIAL TRANSITION:

FACTIONAL CONFLICT IN DAHOMEY IN THE

CONTEXT OF THE ENDING OF THE ATLANTIC SLAVE TRADE
Authors: LAW ROBIN
Published: July 2002

In 1858, after a reign of forty years, King Gezo of Dahomey died
and was

succeeded by one of his sons called Badahun, who took the royal name of

Glele by which he is more generally known. Badahun had been Gezo's

designated heir apparent for at least nine years prior to this but his
accession

to the throne was nevertheless challenged. The name Glele which he adopted

alludes to these challenges, being according to Dahomian tradition

abbreviated from the aphorism Glelile ma ñõn ze,

‘You cannot take away a

farm [gle]’, meaning that he would not

allow anyone to appropriate the fruits of his

labours, which is explained as expressing ‘his contempt for the attacks
to

which he had been exposed as heir apparent’.
RESEARCH IN SAHARAN HISTORY
Authors: MCDOUGALL E. ANN
Published: July 2002

Desert Frontier: Ecological and Economic Change
along the Western Sahel, 1600–1850. By JAMES L. A.
WEBB JR.
Madison and London: University of Wisconsin
Press, 1995. Pp. xxvi+227. £40.95 (ISBN 0-299-14330-9); £17.95,
paperback
(ISBN 0-299-14334-1).

In contrast to the desert itself, the Sahara as subject of historical
(re)construction
is currently displaying signs of health and vitality. It is enticing historians
into a
range of theoretical and methodological domains deriving from other disciplines,

and simultaneously attracting scholars from other disciplines to play out
their own
explorations around its contours. For a space which seems to have no difficulty

occupying well-delineated and identified areas in every genre of cartographical

representation, the Sahara is surprisingly difficult
to ‘locate’ in academic discourse.
Its identity, in current parlance, is a popular focus of speculation and
debate,
challenging conventional notions of its location, both in time and in space.
One of
these challenges is engagingly articulated in the recent publication of
economic
historian James Webb Jr. His Desert Frontier: Ecological and Economic
Change
along the Western Sahel, 1600–1850, invites
wider participation in this ‘search for
the Sahara’ and in so doing, encourages broader understanding of
just where
‘Saharan studies’ and in particular Saharan history and Saharan
society stand in
these so-called post-colonial times.
Effects of plant density on intercropped wheat and field beans in

an organic farming system
Authors: BULSON H. A. J. , SNAYDON R. W. , STOPES C. E.
Published: July 2002

In field trials in 1987/88 near Pangbourne, England, wheat

(Triticum aestivum) and field beans (Vicia faba) were

grown in an organic farming system as sole crops and additive

intercrops. The sole crops were grown at 25, 50, 75, 100 and 150% of

the recommended density (RD) for conventionally grown crops. The

intercrops consisted of all density combinations of wheat and beans

from 25 to 100% RD in a factorial experiment. The grain yield of sole

cropped wheat and beans increased significantly as their density was

increased. The highest yield of both was achieved at 100% RD,

indicating that the conventional recommendation was the optimum when

applied to organically grown crops. Land equivalent ratio (LER) values

for the intercrops were significantly greater than 1·0 when the

wheat was sown at > 5% RD and beans at > 50% RD. The highest LER

of 1·29 was achieved when wheat and beans were both sown at 75%

RD. There was resource complementarity, expressed as relative yield

total (RYT) > 1·0, in all of the density combinations. There

was a significant decrease in resource complementarity with increasing

wheat and bean density. The nitrogen content of the wheat grain and

whole plant biomass was significantly increased when the density of

beans in the intercrops was increased; this was reflected in a

significant increase in grain protein at harvest. The total amount of N

accumulated by the wheat, however, decreased with increasing bean

density due to a reduction in the biomass of wheat. Beans also showed a

significant increase in %N as the density of the other component

increased and a decrease in total N accumulation due to reduced

biomass. All of the intercrops accumulated more N than the sole cropped

wheat, but did not exceed that accumulated by sole-cropped beans. The

biomass of weeds was greater under beans than under wheat. Weed biomass

in intercrops was significantly reduced when the density of wheat and

beans was increased, resulting in a lower weed biomass in the

intercrops than was achieved in either the sole cropped wheat or beans.

The N content of weeds was significantly reduced with increasing wheat

density but was significantly increased with increasing bean density.

The total amount of N accumulated by weeds per unit area was reduced

significantly by increasing the density of both components. The levels

of disease on the wheat were low, but mildew (Erysiphe

graminis) increased significantly as bean density increased. The

incidence of chocolate spot (Botrytis fabae) increased

significantly with increased bean density. The experiment demonstrated

that it was possible to harvest the crop with a combine harvester and

the wheat and beans can be planted separately mechanically, therefore

this system is suited to mechanized agricultural systems.
The relative effects of drought stress and virus yellows
on the yield of sugarbeet in the UK, 1980–95
Authors: JAGGARD K. W. , DEWAR A. M. , PIDGEON J. D.
Published: July 2002

Drought stress and virus yellows disease are two of the major problems

of sugarbeet crop production
in the UK. We have calculated the annual national drought losses from 1980

to 1995 by using long
term data sets for two sites (IACR-Broom's Barn, Suffolk and ADAS

Gleadthorpe, Nottinghamshire)
to relate yield loss to cumulative potential summer moisture deficit, and

combining these relationships
with regional meteorological records, soil type and crop distribution data.

Experimentally measured relationships between yield losses and the timing
of virus yellows
infection were combined with annual survey data of the extent of the problem,
and calculated
infection dates from the UK aphid suction trap network, to calculate
actual national annual losses
to the disease. Potential losses in the absence of control measures were

then calculated by use of data from trials and surveys of pesticide use.

The results showed a mean annual loss of production to drought stress
of
141000 t/year of sugar,
10·5% of production, with a loss to the industry of
£27·9 million. Losses in individual years varied
from zero to 2·5 times the mean figure. Actual losses to virus
yellows were much smaller, due to the
efficacy of treatments, averaging 24700 t/year of sugar (1·8%

of national yield, financial loss £5·5
million). Average potential virus yellows losses in the absence of control

measures were approximately double this.

Control of virus yellows is a major, cost-effective contributor to
rising and consistent sugarbeet
production. Nationally, irrigation has made little impact on drought losses

and, due to constraints
in surface water supply, this situation appears likely to continue. Improved

drought stress tolerance
represents the largest single opportunity for yield and profitability
improvement of the sugarbeet crop
in the UK at present. Predicted climate change appears likely to increase

the severity of both drought
and disease stresses. Drought stress appears relatively less important
in other NW European
sugarbeet-growing areas.
Going International: Presidential Activity in the

Post-Modern Presidency
Authors: SMITH MICHAEL J.
Published: July 2002

A century ago, Woodrow Wilson rejected as unnatural the idea of
a

static political system tethered by a mechanical set of checks and balances.

He said “Government is not a machine but a living thing. It is modified

by its environment, necessitated by its tasks, shaped to its functions
by the

sheer pressure of living.”

In a similar vein, Dodd argued that, by its very

nature, the historical process creates dynamic change. He recommended

thinking in terms of the “transformational analysis”

of the circumstances

in which the office of the presidency is fundamentally altered. To speak
of

such transformation is not to deny the continuities between presidents,

but merely to emphasize the significance of differences. The theory of
the

modern presidency, starting under FDR in the 1930s is, Dodd said, a

significant example of an inherently time bound concept.

This paper picks up Rose's gauntlet that suggests that internal changes
within

America and changes in the world in which it has become an increasingly

important actor in the last half century, together raise the possibility
of a

further transformation in terms of which we should now think

of a post-modern presidency.
NEONATAL MORTALITY AND MATERNAL HEALTH CARE IN NEPAL: SEARCHING FOR PATTERNS OF ASSOCIATION
Authors: SHAKYA KUSHUM , McMURRAY CHRISTINE
Published: July 2002

This study explores the factors associated with neonatal mortality and maternal health care in Nepal. The subjects were 4375 births reported in the 1996 Nepal Family Health Survey. Maternal and child health care was found to have a significant association with neonatal mortality, although preceding birth interval and sex of child had stronger effects. Four aspects of maternal care were found to be highly associated with region, household ownership of assets, mother’s education and father’s education. This indicates that accessibility, affordability and availability of maternal health care are important factors to consider in future research on neonatal mortality.
Chromatographic characterization of ovine κ-casein macropeptide
Authors: MORENO F. JAVIER , RECIO ISIDRA , OLANO AGUSTÍN , LÓPEZ-FANDIÑO ROSINA
Published: July 2002

Ovine casein macropeptide (CMP) was characterized by anion-exchange
FPLC and reversed-phase (RP) HPLC. To study heterogeneity (the degree of
glycosylation and phosphorylation), CMP was desialylated with neuraminidase and
dephosphorylated with acid phosphatase. Following RP-HPLC, the main CMP
components were identified using either on-line or off-line mass spectrometry. The
most abundant ovine CMP component was a diphosphorylated carbohydrate-free
form, followed by one or two monophosphorylated and a non-phosphorylated asialo-aglyco species. Aglyco non-phosphorylated, monophosphorylated and diphosphorylated
forms were in the ratio 3[ratio ]20[ratio ]77. Only ∼ 30% of ovine CMP was glycosylated.
Assuming that the monosaccharide fraction of ovine CMP is composed of
N-acetylgalactosamine, galactose and N-glycolylneuraminic acid, molecular masses
consistent with the presence of CMP containing tetra-, tri-, di- and monosaccharide
were identified.
Pinkish colouration in Cheddar cheese – description and factors contributing to its formation
Authors: MARTLEY FRANK G. , MICHEL VALÉRIE
Published: July 2002

During a routine inspection of Cheddar cheese manufactured at a commercial
factory in New Zealand, some lots of 6-month-old cheese were found to have
developed a pinkish colouration on the surface of the 20 kg blocks of cheese.
Colouration did not always occur uniformly on all six faces of the rectangular cheese
block, or even on a single face of the block. Furthermore, not all blocks from within
the same day's manufacture were equally affected. When an affected block was
removed from its bag and cut across, colouration was sometimes found to penetrate
approximately 1–2 cm down into the cheese. In those blocks where a plug of cheese
had been removed previously, a pinkish zone surrounded the plug-hole cavity.

The pinkish colouration was observed to fade slowly (over about 12–24 h) when
the cheese surface was exposed to air.

Annatto, known to cause pink discolouration in “coloured” Cheddar cheese
(Govindarajan & Morris, 1973) and in processed cheese made using coloured
Cheddar, was not used in the manufacture of the present cheeses and could therefore
be excluded as a cause of the colouration.

The flavour profiles of all affected cheeses were considered by experienced
industry cheese graders to be easily within the normal range of flavour profile
expected for a cheese of this type i.e. there was no evidence of any off-flavour
development.

The present short communication describes the microbiological and chemical
investigations carried out to determine the origin and nature of the pinkish
colouration in Cheddar cheese.
Synthesis and distribution of cytokeratins in healthy and ulcerated bovine claw epidermis
Authors: HENDRY KAY A. K. , MACCALLUM AMANDA J. , KNIGHT CHRISTOPHER H. , WILDE COLIN J.
Published: July 2002

Keratinization of the epidermal cells of the bovine claw generates the horn that gives the tissue its mechanical strength. Disruption of keratinization is likely to have a detrimental effect on the strength and integrity of the horn, and could lead to solar lesions and lameness. As part of a wider investigation of the cell biological causes of lameness in dairy animals, we have compared keratin synthesis and distribution in healthy bovine claw tissue with those in hooves with solar ulcers. Protein synthesis was measured by [35S]-labelled amino acid incorporation in claw tissue explant cultures. [35S]-labelled protein synthesis was higher in tissue from diseased claws than in healthy claws, and highest at the ulcer site. The identity of proteins synthesised in vitro did not differ between healthy and diseased tissue. DNA synthesis indicative of cell proliferation was also elevated in diseased tissue. Immunoblotting after one- or two-dimensional electrophoresis showed cytokeratins (CK) 4, 5/6, 10 and 14 to be amongst those expressed in healthy claw tissue. The relative abundance of these keratins was not altered in healthy regions of ulcerated hooves, nor at the ulcer site, but CK16, not usually found in healthy tissue, was detected in the sole of diseased claws. CK5/6 and CK14 were shown by immunohistochemistry to be present in the basal epidermis of healthy tissue, whereas CK10 was found in supra-basal layers. In healthy tissue from ulcerated claws, this distribution was unaltered, but at the site of solar ulcers, CK5/6 and CK14 were each found in both basal and supra-basal epidermis. The study suggests that solar ulceration of the bovine claw is not associated with gross alteration in the keratin composition of the tissue, but causes abnormal distribution of cytokeratins, perhaps as a result of loss of positional cues from the basement membrane. Ulceration did, however, stimulate cell repair involving epidermal protein synthesis (including keratins), and keratinocyte proliferation.
Machine milking of Ostfriesian and Lacaune dairy sheep:
udder anatomy, milk ejection and milking characteristics
Authors: BRUCKMAIER RUPERT M. , PAUL GEORG , MAYER HARALD , SCHAMS DIETER
Published: July 2002

Mammary cistern anatomy derived from ultrasound measurement, milk

ejection in response to exogenous oxytocin and oxytocin release and milking

characteristics with and without manual prestimulation in early
(months 2–4) and
late (months 5–8) lactation were investigated in Lacaune and
Ostfriesian dairy ewes.
Vertical ultrasound cisternal cross sections of the cisternal cavities

did not differ in
the two breeds, whereas the cisternal area fraction located lower than
the exit into
the teat channel was larger in Ostfriesian than in Lacaune sheep. The cisternal
area
enlarged within 1 min in response to i.v. oxytocin injection,
indicating milk ejection.
During milking, oxytocin concentrations in Lacaune generally increased

dramatically within 0·5 min from the start of prestimulation
or milking, whereas only
slight or no oxytocin release was detected during milking without prestimulation
in
Ostfriesian ewes. Prestimulation induced oxytocin release in Ostfriesian
sheep within
1–2 min after the start of milking, indicating delayed response
to stimulation. Two
peaked milk flow curves were observed when oxytocin release and milk ejection

occurred only after removal of cisternal milk. This type of milk flow was
more
frequent in Ostfriesian than in Lacaune ewes and was reduced in both breeds
by
prestimulation, while the frequency of one peaked milk flow curves increased.
During
the course of lactation, milk yield, main milk fraction and
milk flow rates decreased,
while stripping yield was almost unchanged. Although milk yield was similar
in both
breeds, milk flow was lower and stripping yield was higher in Ostfriesian
than in
Lacaune ewes. We conclude that milk ejection in ewes occurred in response
to
elevated oxytocin concentrations. In Ostfriesian ewes reduced and delayed
oxytocin
response to teat stimulation resulted in milk ejection only during stripping.

Therefore, and probably because a larger volume of the cistern was located
below the
teat exit in the Ostfriesian breed, stripping yield was higher in Ostfriesian
than in
Lacaune sheep.
Richard Hooker and the Problem of
Authority in the Elizabethan Church
Authors: PERROTT M. E. C.
Published: July 2002

In the spring of 1593 Richard Hooker published the first
part of his work Of the laws of ecclesiastical polity
which has come to be known
as the most famous attempt to persuade Elizabethan Puritans to
conform to the laws of the English Church.
Hooker's writings have
received more scholarly attention than those of any other
contemporary church polemicist but no consensus has, as yet,
been arrived at regarding
the nature of his argument or the way in which his ideas
addressed the
major issues of Elizabethan church controversy. It is my
intention in this
essay to focus on these issues and thus provide some insight
into the details
of Hooker's theory of law and its broader significance
as an argument
relating to the legislative authority of the Church of England.
Spectral and hyper eddy viscosity in high-Reynolds-number turbulence
Authors: CERUTTI STEFANO , MENEVEAU CHARLES , KNIO OMAR M.
Published: July 2002

For the purpose of studying the spectral properties of energy transfer between large
and small scales in high-Reynolds-number turbulence, we measure the longitudinal
subgrid-scale (SGS) dissipation spectrum, defined as the co-spectrum of the SGS
stress and filtered strain-rate tensors. An array of four closely spaced X-wire probes
enables us to approximate a two-dimensional box filter by averaging over different
probe locations (cross-stream filtering) and in time (streamwise filtering using Taylor's
hypothesis). We analyse data taken at the centreline of a cylinder wake at Reynolds
numbers up to Rλ ∼ 450. Using the assumption of local isotropy, the longitudinal SGS
stress and filtered strain-rate co-spectrum is transformed into a radial co-spectrum,
which allows us to evaluate the spectral eddy viscosity,
v(k, kΔ). In agreement with
classical two-point closure predictions, for graded filters, the spectral eddy viscosity
deduced from the box-filtered data decreases near the filter wavenumber kΔ. When
using a spectral cutoff filter in the streamwise direction (with a box-filter in the cross-stream direction) a cusp behaviour near the filter scale is observed. In physical space,
certain features of a wavenumber-dependent eddy viscosity can be approximated
by a combination of a regular and a hyper-viscosity term. A hyper-viscous term is
also suggested from considering equilibrium between production and SGS dissipation
of resolved enstrophy. Assuming local isotropy, the dimensionless coefficient of the
hyper-viscous term can be related to the skewness coefficient of filtered velocity
gradients. The skewness is measured from the X-wire array and from direct numerical
simulation of isotropic turbulence. The results show that the hyper-viscosity coefficient
is negative for graded filters and positive for spectral filters. These trends are in
agreement with the spectral eddy viscosity measured directly from the SGS stress–strain
rate co-spectrum. The results provide significant support, now at high Reynolds
numbers, for the ability of classical two-point closures to predict general trends of
mean energy transfer in locally isotropic turbulence.
An experimental study of two-dimensional surface water waves propagating on depth-varying currents.
Part 1. Regular waves
Authors: SWAN C. , CUMMINS I. P. , JAMES R. L.
Published: July 2002

This paper describes an experimental study of two-dimensional surface water waves
propagating on a depth-varying current with a non-uniform vorticity distribution. The
investigation is divided into two parts. The first concerns the ‘equilibrium’ conditions
in which the oscillatory wave motion and the current co-exist. Measurements of
the water-surface elevation, the water-particle kinematics, and the near-bed pressure
fluctuations are compared to a number of wave and wave–current solutions including
a nonlinear model capable of incorporating the vertical structure of the current profile.
These comparisons confirm that the near-surface vorticity leads to an important
modification of the dispersion equation, and thus affects the nature of the wave-induced
orbital motion over the entire water depth. However, the inclusion of vorticity-dependent
terms within the dispersion equation is not sufficient to define the combined
wave–current flow. The present results suggest that vorticity may lead to a significant
change in the water-surface profile. If a current is positively sheared, dU/dz > 0,
with negative vorticity at the water surface, as would be the case in a wind-driven
current, a wave propagating in the same direction as the current will experience
increased crest–trough asymmetry due to the vorticity distribution. With higher and
sharper wave crests there is a corresponding increase in both the maximum water-particle
accelerations and the maximum horizontal water-particle velocities. These
results are consistent with previous theoretical calculations involving uniform vorticity
distributions (Simmen & Saffman 1985 and Teles da Silva & Peregrine 1988).

The second part of the study addresses the ‘gradually varying’ problem in which
there are changes in the current, the wavelength and the wave height due to the
initial interaction between the wave and the current. These data show that there is
a large and non-uniform change in the current profile that is dependent upon both
the steepness of the waves and the vorticity distribution. Furthermore, comparisons
between the measured wave height change and a number of solutions based on the
conservation of wave action, confirm that the vorticity distribution plays a dominant
role. In the absence of a conservation equation for wave action appropriate for
nonlinear waves on a depth-varying current, an alternative approach based on the
conservation of total energy flux, first proposed by Longuet-Higgins & Stewart (1960),
is shown to be in good agreement with the measured data.
Vortex formation in front of a piston moving through a cylinder
Authors: ALLEN J. J. , CHONG M. S.
Published: July 2002

This paper contains the details of an experimental study of the vortex formed in front
of a piston as it moves through a cylinder. The mechanism for the formation of this
vortex is the removal of the boundary layer forming on the cylinder wall in front of
the advancing piston. The trajectory of the vortex core and the vorticity distribution
on the developing vortex have been measured for a range of piston velocities. Velocity
field measurements indicate that the vortex is essentially an inviscid structure at the
Reynolds numbers considered, with viscous effects limited to the immediate corner
region. Inviscid flow is defined in this paper as being a region of the flow where
inertial forces are significantly larger than viscous forces. Flow visualization and
vorticity measurements show that the vortex is composed mainly of material from
the boundary layer forming over the cylinder wall. The characteristic dimension of
the vortex appears to scale in a self-similar fashion, while it is small in relation to
the apparatus length scale. This scaling rate of t0.85+0.7m, where the piston speed is
described as a power law Atm, is somewhat
faster than the t3/4 scaling predicted
by Tabaczynski et al. (1970) and considerably faster than a viscous scaling rate of
t1/2. The reason for the structure scaling more rapidly than predicted is the self-induced effect of the secondary vorticity that is generated on the piston face. The
vorticity distribution shows a distinct spiral structure that is smoothed by the action
of viscosity. The strength of the separated vortex also appears to scale in a self-similar
fashion as t2m+1. This rate is the same as suggested from a simple model of the flow
that approximates the vorticity being ejected from the corner as being equivalent
to the flux of vorticity over a flat plate started from rest. However, the strength
of the vorticity on the separated structure is 25% of that suggested by this model,
sometimes referred to as the ‘slug’ model. Results show that significant secondary
vorticity is generated on the piston face, forming in response to the separating primary
vortex. This secondary vorticity grows at the same rate as the primary vorticity and
is wrapped around the outside of the primary structure and causes it to advect away
from the piston surface.
Inhomogeneity and anisotropy effects on the redistribution term in Reynolds-averaged Navier–Stokes modelling
Authors: MANCEAU RÉMI , WANG MENG , LAURENCE DOMINIQUE
Published: July 2002

A channel flow DNS database at Reτ = 590 is used to assess the validity of modelling
the redistribution term in the Reynolds stress transport equations by elliptic relaxation.
The model assumptions are found to be globally consistent with the data. However, the
correlation function between the fluctuating velocity and the Laplacian of the pressure
gradient, which enters the integral equation of the redistribution term, is shown to
be anisotropic. It is elongated in the streamwise direction and strongly asymmetric
in the direction normal to the wall, in contrast to the isotropic, exponential model
representation used in the original elliptic relaxation model. This discrepancy is the
main cause of the slight amplification of the energy redistribution in the log layer
as predicted by the elliptic relaxation equation. New formulations of the model are
proposed in order to correct this spurious behaviour, by accounting for the rapid
variations of the length scale and the asymmetrical shape of the correlation function.
These formulations do not rely on the use of so-called ‘wall echo’ correction terms to
damp the redistribution. The belief that the damping is due to the wall echo effect is
called into question through the present DNS analysis.
A study of three-dimensional aspects of vortex shedding from a

bluff body with a mild geometric disturbance
Authors: TOMBAZIS N. , BEARMAN P. W.
Published: July 2002

Experiments have been carried out to study the

three-dimensional characteristics of vortex shedding from a

half-ellipse shape with a blunt trailing edge. In order to control

the occurrence of vortex dislocations, the trailing edges of the

models used were constructed with a series of periodic waves across

their spans. Flow visualization was carried out in a water tunnel at

a Reynolds number of 2500, based on trailing-edge thickness. A number

of shedding modes were observed and the sequence of mode transitions

recorded. Quantitative data were obtained from wind tunnel

measurements performed at a Reynolds number of 40000. Two shedding

frequencies were recorded with the higher frequency occurring at

spanwise positions coinciding with minima in the chord. At these same

positions the base pressure was lowest and the vortex formation

length longest. Arguments are put forward to explain these

observations. It is shown that the concept of a universal Strouhal

number holds, even when the flow is three-dimensional. The spanwise

variation in time-average base pressure is predicted using the

estimated amount of time the flow spends at the two shedding

frequencies.
Suboptimal control of turbulent channel flow for drag reduction
Authors: LEE CHANGHOON , KIM JOHN , CHOI HAECHEON
Published: July 2002

Two simple feedback control laws for drag reduction are derived
by applying a
suboptimal control theory to a turbulent channel flow. These new feedback
control
laws require pressure or shear-stress information only at the wall, and
when applied
to a turbulent channel flow at Reτ=110, they result
in
16–22% reduction in the
skin-friction drag. More practical control laws requiring only the local
distribution of
the wall pressure or one component of the wall shear stress are also derived
and are
shown to work equally well.
Self-similarity of time-evolving plane wakes
Authors: MOSER ROBERT D. , ROGERS MICHAEL M. , EWING DANIEL W.
Published: July 2002

Direct numerical simulations of three time-developing turbulent
plane wakes have
been performed. Initial conditions for the simulations were obtained using
two realizations
of a direct simulation from a turbulent boundary layer at momentum-thickness

Reynolds number 670. In addition, extra two-dimensional disturbances were
added in
two of the cases to mimic two-dimensional forcing. The wakes are allowed
to evolve
long enough to attain approximate self-similarity, although in the strongly
forced case
this self-similarity is of short duration. For all three flows, the mass-flux
Reynolds
number (equivalent to the momentum-thickness Reynolds number in spatially
developing
wakes) is 2000, which is high enough for a short k−5/3

range to be evident in the streamwise one-dimensional velocity spectra.

The spreading rate, turbulence Reynolds number, and turbulence intensities
all
increase with forcing (by nearly an order of magnitude for the strongly
forced
case), with experimental data falling between the unforced and weakly forced
cases.
The simulation results are used in conjunction with a self-similar analysis
of the
Reynolds stress equations to develop scalings that approximately collapse
the profiles
from different wakes. Factors containing the wake spreading rate are required
to
bring profiles from different wakes into agreement. Part of the difference
between
the various cases is due to the increased level of spanwise-coherent (roughly

two-dimensional) energy in the forced cases. Forcing also has a significant
impact on
flow structure, with the forced flows exhibiting more organized large-scale
structures
similar to those observed in transitional wakes.
Bénard–Marangoni convection: planforms and
related theoretical predictions
Authors: BRAGARD J. , VELARDE M. G.
Published: July 2002

A derivation is given of the amplitude equations governing pattern
formation in
surface tension gradient-driven Bénard–Marangoni
convection. The amplitude equations
are obtained from the continuity, the Navier–Stokes and the Fourier
equations in the
Boussinesq approximation neglecting surface deformation and buoyancy. The
system
is a shallow liquid layer heated from below, confined below by a rigid
plane and
above with a free surface whose surface tension linearly depends on temperature.
The
amplitude equations of the convective modes are equations of the Ginzburg–Landau

type with resonant advective non-variational terms. Generally, and in agreement
with
experiment, above threshold solutions of the equations correspond to an
hexagonal
convective structure in which the fluid rises in the centre of the cells.
We also
analytically study the dynamics of pattern formation leading not only to
hexagons
but also to squares or rolls depending on the various dimensionless parameters
like
Prandtl number, and the Marangoni and Biot numbers at the boundaries. We
show
that a transition from an hexagonal structure to a square pattern is possible.
We
also determine conditions for alternating, oscillatory transition between
hexagons and
rolls. Moreover, we also show that as the system of these amplitude equations
is
non-variational the asymptotic behaviour (t→∞)
may not correspond to a steady
convective pattern. Finally, we have determined the Eckhaus band for hexagonal
patterns
and we show that the non-variational terms in the amplitude equations enlarge

this band of allowable modes. The analytical results have been checked
by numerical
integration of the amplitude equations in a square container. Like in experiments,

numerics shows the emergence of different hexagons, squares and rolls according
to
values given to the parameters of the system.
Bacterial bioconvection: weakly nonlinear theory for pattern selection
Authors: METCALFE A. M. , PEDLEY T. J.
Published: July 2002

Complex bioconvection patterns are observed when a suspension of
the oxytactic
bacterium Bacillus subtilis is placed in a chamber with its upper
surface open to
the atmosphere. The patterns form because the bacteria are denser than
water and
swim upwards (up an oxygen gradient) on average. This results in an unstable
density
distribution and an overturning instability. The pattern formation is dependent
on
depth and experiments in a tilted chamber have shown that as the depth
increases
the first patterns formed are hexagons in which the fluid flows down in
the centre.

The linear stability of this system was analysed by Hillesdon &
Pedley (1996) who
found that the system is unstable if the Rayleigh number Γ

exceeds a critical value,
which depends on the wavenumber k of the disturbance as well as
on the values of
other parameters. Hillesdon & Pedley found that the
critical wavenumber kc could be
either zero or non-zero, depending on the parameter values.

In this paper we carry out a weakly nonlinear analysis to determine
the relative
stability of hexagon and roll patterns formed at the onset of bioconvection.
The
analysis is different in the two cases kc≠0

and kc=0. For the
kc≠0 case (which
appears to be more relevant experimentally) the model does predict down
hexagons,
but only for a certain range of parameter values. Hence the analysis allows
us to refine
previous parameter estimates. For the kc=0

case we carry out a two-dimensional
analysis and derive an equation describing the evolution of the horizontal
planform
function.
Experiments on nonlinear gravity–capillary waves
Authors: SHEMER LEV , CHAMESSE MELAD
Published: July 2002

Benjamin–Feir instability of nonlinear gravity–capillary
waves is studied
experimentally. The experimental results are compared with computations
performed for values
of wavelength and steepness identical to those employed in the experiments.
The
theoretical approach is based on the Zakharov nonlinear equation which
is modified
here to incorporate weak viscous dissipation. Experiments are performed
in a wave
ume which has an accurately controlled wavemaker for generation of the
carrier
wave, as well as an additional independent conical wavemaker for generation
of
controlled three-dimensional disturbances. The approach adopted in the
present experimental
investigation allows therefore the determination of the actual boundaries

of the instability domain, and not just the most unstable disturbances.
Instantaneous
surface elevation measurements are performed with capacitance-type wave
gauges.
Multipoint measurements make it possible to determine the angular dependence
of
the amplitude of the forced and unforced disturbances, as well as their
variation along
the tank. The limits of the instability domains obtained experimentally
for each set of
carrier wave parameters agree favourably with those computed numerically
using the
model equation. The numerical study shows that application of the Zakharov
equation,
which is free of the narrow-band approximation adopted in the derivation
of
the nonlinear Schrödinger (NLS) equation, may lead to qualitatively different
results
regarding the stability of nonlinear gravity–capillary waves. The
present experiments
support the results of the numerical investigation.
Drag reduction in fish-like locomotion
Authors: BARRETT D. S. , TRIANTAFYLLOU M. S. , YUE D. K. P. , GROSENBAUGH M. A. , WOLFGANG M. J.
Published: July 2002

We present experimental force and power measurements demonstrating that the power
required to propel an actively swimming, streamlined, fish-like body is significantly
smaller than the power needed to tow the body straight and rigid at the same speed
U. The data have been obtained through accurate force and motion measurements
on a laboratory fish-like robotic mechanism, 1.2 m long, covered with a flexible
skin and equipped with a tail fin, at Reynolds numbers up to 106, with turbulence
stimulation. The lateral motion of the body is in the form of a travelling wave with
wavelength λ and varying amplitude along the length, smoothly increasing from the
front to the tail end. A parametric investigation shows sensitivity of drag reduction
to the non-dimensional frequency (Strouhal number), amplitude of body oscillation
and wavelength λ, and angle of attack and phase angle of the tail fin. A necessary
condition for drag reduction is that the phase speed of the body wave be greater than
the forward speed U. Power estimates using an inviscid numerical scheme compare
favourably with the experimental data. The method employs a boundary-integral
method for arbitrary flexible body geometry and motions, while the wake shed from
the fish-like form is modelled by an evolving desingularized dipole sheet.
Dynamics and flow structures in the turbulent
wake of rigid and flexible cylinders subject to
vortex-induced vibrations
Authors: EVANGELINOS CONSTANTINOS , KARNIADAKIS GEORGE EM
Published: July 2002

We present simulation results of vortex-induced vibrations of an infinitely long flexible
cylinder at Reynolds number Re = 1000, corresponding to a ‘young’ turbulent wake
(i.e. exhibiting a small inertial subrange). The simulations are based on a new class
of spectral methods suitable for unstructured and hybrid grids. To obtain different
responses of the coupled flow–structure system we vary the structure's bending stiffness
to model the behaviour of a vibrating inflexible (rigid) cylinder, a cable, and a beam.
We have found that unlike the laminar flow previously studied, the amplitude of
the cross-flow oscillation is about one diameter for the cable and the beam, close to
experimental measurements, but is lower for the rigid cylinder. We have also found
that for the latter case the flow response corresponds to parallel shedding, but for
the beam and cable with free endpoints a mixed response consisting of oblique and
parallel shedding is obtained, caused by the modulated travelling wave motion of
the structure. This mixed shedding pattern which alternates periodically along the
span can be directly related to periodic spatial variation of the lift force. In the
case of structures with pinned endpoints a standing wave response is obtained for
the cylinder; lace-like flow structures are observed similar to the ones seen in the
laminar regime. Examination of the frequency spectra in the near wake shows that at
Re = 1000 all cases follow a −5/3 law in the inertial range, which
extends about half a decade in wavenumber. However, these spectra are
different in all three cases both
in low and high frequencies, with the exception of the beam and cable, for which the
high-frequency portion is identical despite the differences in the displacement time
history and the large-scale features of the corresponding flow.
Perturbation theory for Rankine vortices
Authors: GORSHKOV KONSTANTIN A. , OSTROVSKY LEV A. , SOUSTOVA IRINA A.
Published: July 2002

A perturbation scheme is constructed to describe the evolution of stable, localized
Rankine-type hydrodynamic vortices under the action of disturbances such as density
stratification. It is based on the elimination of singularities in perturbations by using
the necessary orthogonality conditions which determine the vortex motion. Along with
the discrete-spectrum modes of the linearized problem which can be kept finite by
imposing the orthogonality conditions, the continuous-spectrum perturbations play
a crucial role. It is shown that in a stratified fluid, a single (monopole) vortex can
be destroyed due to the latter modes before it drifts very far, whereas a vortex pair
preserves its stability for a longer time. The motion of the latter is studied in two
cases: smooth stratification and a density jump. For the motion of a pair under a
small angle to the interface, a complete description is given in the framework of our
theory, including the effect of reflection of the pair from a region with slightly larger
density.
Electoral Juggling: A Comparative History of the Corruption of Suffrage in Latin America, 1830–1930
Authors: POSADA-CARBÓ EDUARDO
Published: July 2002

This article examines, from a comparative perspective, those electoral
practices labelled as ‘corrupt’ in Latin America between 1830 and 1930, in order
to gain a fuller appreciation of the significant role played by elections in the
history of the region. The article starts by using the term ‘electoral corruption’
in its general sense, as often used by contemporaries themselves when referring
to the various practices that, in their view, distorted the vote, and therefore the
meaning of suffrage. From this general definition, the article moves on to
distinguish between the different types of corrupt practice, with the aim of
identifying the extent to which they affected electoral competition. By offering a
revision of the assumptions that have hitherto served to undermine the historical
meaning of the suffrage, this article aims to encourage the study of electoral
history in the region. The examination of electoral corruption is therefore
preceded by a brief survey of the historiography of Latin American elections.
Popular Support for Regional
Economic Integration in Latin
America
Authors: SELIGSON MITCHELL A.
Published: July 2002

Regional economic integration schemes abound in Latin America,
yet
very little is known about the degree of popular support for such programmes.

Now that democratic regimes rule in almost all of Latin America, public
opinion
can have an important impact on national policies. This paper examines
the
attitudes toward economic integration in 17 mainland Latin American countries

with interview data from over 18,000 people. Bi-variate and multivariate
analyses
are conducted on the factors related to support for regional integration.

Perceived benefits of integration and perceptions of personal and national

economic situation prove to be important factors, as are higher levels
of
education, support for democracy and gender (males favour integration more

than females). Two novel findings are that a positive opinion of the European

Union along with satisfaction with the functioning of democracy are both
linked
to greater support for integration.
Being taken for a ride: privatisation of the Dar es Salaam transport system 1983–1998
Authors: Rizzo Matteo
Published: July 2002

This paper analyses the effects of privatisation and deregulation of the Dar es Salaam transport system. It starts with an account of the decline of the government-owned transport company and the first opening of the market to private buses in 1983. The analysis then moves to the progressive deregulation of the sector and its impact on transport supply. Competition between private operators in the oversupplied market manifests itself in non-compliance with safety rules, and inefficiencies in the fare structures. Labour relations with the private sector are then examined to illustrate the logic of the market. The results of a questionnaire answered by 668 workers suggest that the reaction of casual workers to exploitative conditions of employment characterises many aspects of the operation of the transport system. The impact of deregulation is therefore most clearly to be seen in the nature of labour relations within the sector, and it is argued that there is a need for state regulation to monitor and enforce conditions of employment within the private sector if service provision is to be improved.
Peasants, Local Communities, and Central Power in Burundi
Authors: LAELY THOMAS
Published: July 2002

Today Burundi resembles a torn-apart patchwork of Batutsi
and

Bahutu colonies by being divided territorially into almost isolated

enclaves, ethnically purified to a high degree, and more or less closed

off from their surrounding areas. Most Batutsi believe that they can

only live in security if sheltered by the army in various urban

agglomerations, including the capital, Bujumbura. By way of contrast,

most Bahutu are to be found in the hills of the countryside in an often

entrenched and hidden way, and close to economic self-sufficiency.

Such an unusual situation is undoubtedly a big challenge to the

relations that need to be established between state authorities and

citizens in rural as well as urban areas.
Reflections on donors, opposition and popular will in the 1996 Zambian
general elections
Authors: van Donge Jan Kees
Published: July 2002

The Zambian general elections held on 18 November 1996 to elect
a
president and parliament are of more than merely national interest.
Even before the elections took place, a vocal opposition already
doubted their genuineness, and these claims have found considerable
international sympathy. The Zambian government and those who
voted them into power for a second term, however, consider these
elections a hallmark of the success of the reintroduction of multi-partyism, which Zambia was one of the first, and one of the most
successful, to reintroduce in Africa. These elections, therefore, provide

a case in which to analyse a triangular interaction which is common in

Africa: the interaction between an incumbent political group, an
opposition which does not accept the victory of the former, and the
international community. This article aims to offer a theoretical
perspective on the way in which these three groups of actors intermesh;

but, in order to ground these more theoretical concerns in an
understanding of the empirical realities, an attempt is made first to
capture the essence of the conflicts involved.