bluuebunny/crossref_metadata_2025 huggingface dataset:
Transmission pattern of hobo transposable element in
transgenic lines of Drosophila melanogaster
Authors: LADEVEZE VERONIQUE , GALINDO IBO , CHAMINADE NICOLE , PASCUAL LUIS , PERIQUET GEORGES , LEMEUNIER FRANCOISE
Published: July 2002

This study is an attempt to trace the fate of hobo
elements in the genomes of E strains of
Drosophila melanogaster that have been transfected with pHFL1,
a plasmid containing an
autonomous hobo. Such long-term population studies (over
105 generations) could be very useful
for better understanding the population and genomic dynamics of transposable
elements and their
pattern of insertions. Molecular analyses of hobo elements in the
transfected lines were performed
using Southern blots of XhoI-digested genomic DNAs. The
complete element was observed in all
six injected lines. In two lines we observed, at generation 100, two
deleted elements, which did not
correspond to Th1 and Th2. The results obtained by the

in situ method show that the number of
hybridization sites increases in each line and prove that the hobo

element may be amplified in an
RM genome. The hobo activity does not seem to be systematically

correlated with the number of
hobo elements. After generation 85, the evolution of the hobo

element's insertion site number
depends on the injected line. In all lines, the total number of insertions
remains quite small,
between 0 and 11. Hobo elements are located on each of the
chromosomal arms. We describe
‘hotspots’ – insertion sites present in all lines and

in all generations. On the 3R arm, a short
inversion appeared once at generation 85.
Mapping quantitative trait loci for principal components of
bone measurements and osteochondrosis scores in a wild
boar × Large White intercross
Authors: ANDERSSON-EKLUND L. , UHLHORN H. , LUNDEHEIM N. , DALIN G. , ANDERSSON L.
Published: July 2002

Data on osteochondrosis and femur dimensions from 195 F2 pigs from a wild boar × Large White
intercross were analysed with the aim of detecting quantitative trait loci (QTLs) for normal and
disturbed bone formation. The information from numerous recorded traits was summarized by
principal component analysis and analysed by least-squares interval mapping. An increase in the
proportion of wild boar alleles across the genome increased length versus width of femur and
reduced the prevalence of osteochondrosis. The presence of QTLs with an impact on femur
dimensions was indicated on chromosomes 2, 4, 16 and 17 and on osteochondrosis on
chromosomes 5, 13 and 15. A substantial effect of the chromosome 5 QTL calls for further studies
within commercial populations to evaluate whether marker-assisted selection could be used to
reduce the prevalence of osteochondrosis.
Traces of certain classes of holomorphic functions on finite unions of Carleson sequences
Authors: HARTMANN ANDREAS
Published: July 2002

We give a method allowing the generalization of the description of trace spaces of certain classes of holomorphic functions on Carleson sequences to finite unions of Carleson sequences. We apply the result to different classes of spaces of holomorphic functions such as Hardy classes and Bergman type spaces.
THE AGE OF PERICLES IN THE MODERN ATHENS: GREEK HISTORY, SCOTTISH POLITICS, AND THE FADING OF ENLIGHTENMENT
Authors: ALLAN DAVID
Published: July 2002

This article explores changing responses among late Georgian Scots towards Greek history in general and classical Athens in particular. Tracing the early study of Greece through some of the more innovative Scottish Enlightenment scholars, it argues that Periclean Athens long remained a difficult and controversial topic, mainly because eighteenth-century authors found it hard to offer a fully sympathetic treatment of a historical subject strongly associated with radical political democracy. With the defeat of Napoleon, however, and as new ways were sought to celebrate Scotland's own recent imperial, economic, and intellectual achievements, Athenianism gained in credibility, assisted by the rising tide of cultural Hellenism and political Hellenophilia throughout Britain. Plans were laid for a national monument in Edinburgh, modelled on the Athenian Parthenon. Nevertheless, insufficient support was forthcoming and by 1830 the project had stalled. Not least among the causes of this debacle – popularly known as ‘Scotland's Disgrace’ – were the contradictions involved in Athenian symbolism: the abandoned monument ultimately served to represent only the failings of Scotland's tory establishment.
MAKING DEAD MEN SPEAK: LAUDIANISM, PRINT, AND THE WORKS
OF LANCELOT ANDREWES, 1626–1642
Authors: McCULLOUGH PETER
Published: July 2002

This study examines the posthumous competition over the print publication
of works by
Lancelot Andrewes (1555–1626) before the English Civil War.
The print history of the two official
volumes edited by Laud and John Buckeridge (1626), and of competing
editions of texts rejected by
them but printed by puritan publishers, sheds important new light not
only on the formation of the
Andrewes canon, but on Laud's manipulation of the print trade and

his attempts to erect new textual
authorities to support his vision of the church in Britain.
JOHN STREATER AND THE GRAND POLITICK INFORMER
Authors: RAYMOND JOAD
Published: July 2002

The soldier, publisher, and pamphleteer John Streater is a comparatively
neglected
political writer of the 1650s, who represents the turning of the
dispersed Levellers to classical
republicanism. In the 1650s he is seen as a brave and uncompromising
voice of opposition. In the
autumn of 1653 he was prosecuted by Cromwell for publishing a work
entitled The grand politick
informer. This article rediscovers this publication, identifies
it as Streater's first newsbook, and
explores its implications for Streater's career and canon. In
1654 Streater wrote two series of
newsbooks which criticized the Protectorate in an oblique fashion.
The grand politick informer,
a work of unbridled ferocity, shows that Streater learned to tame
his voice after his 1653 prosecution
and imprisonment, and to couch his antagonism to the government in
the language of classical allusion.
THE SOCIAL TRANSFORMATION OF
HOSPITALS AND THE RISE OF
MEDICAL INSURANCE IN FRANCE,
1914–1943
Authors: SMITH TIMOTHY B.
Published: July 2002

This article explores the impact of the First World War on the
social reform movement
in France, emphasizing hospital policy and medical insurance. I argue that
the war gave birth to a
concerted reform movement which succeeded in bringing about fundamental
changes to health care
policy. During the inter-war years, the French embarked on a mission to
replace the traditional
hospital, the maison des pauvres, with modern facilities designed
to cater to the middle class as well
as to the poor. In 1928, a landmark law was passed which extended medical
insurance to workers and
the lower middle class. By 1940, over one half of the population was covered
by medical insurance,
and dozens of modern hospitals had been constructed. The impetuses to this
national reform legislation
were the numerous local experiments, whose stories I examine in some detail.
Despite the image of
Third Republic ‘decadence’, the success of health policy reform
during the 1920s and 1930s shows
that France was indeed capable of important domestic reforms. Under Vichy,
these reforms were
consolidated and after the Liberation, Vichy's efforts were saluted
and affirmed by French politicians.
THE CULTURAL IMPACT OF SCIENCE IN FRANCE: ERNEST RENAN AND THE
VIE DE JÉSUS
Authors: PITT ALAN
Published: July 2002

The publication of Ernest Renan's La Vie de Jésus in 1863 is rightly regarded as a
key moment in French history. The book served as an important symbol of science and free thought in
the battles over the Republic and laïcité, and presented a thesis that characterized French scientific
philosophy in the mid-nineteenth century. Jesus, for Renan, transcended his own culture, rejecting all
social constraints in the pursuit of a unique ideal of the kingdom of God, becoming in the process the
first true individualist in history. Critics ridiculed his arguments, but it was typical of the Romanticism
of the French positivists. Renan's philosophy was rooted not in empiricism, but in an essentially
pantheistic metaphysics, prizing the realization of God within oneself as the highest ethical
achievement. This was an innovation of the highest importance in France, where a traditionalist, but
post-Christian theism had marked social thought since the Revolution. Renan and his generation,
notably Taine, dispensed with the traditionalist religious dualism that typified the social outlook of
Tocqueville, Michelet, and their contemporaries. Far from articulating a materialist dead end in the
history of ideas, their Romantic individualism was critical to later developments in European thought,
including aestheticism and irrationalism.
Changes in liveweight, body condition and scrotal circumference

and their relationships with sexual activity and flock fertility in

Ethiopian Horro rams over a 3-cycle joining period
Authors: GIZAW Solomon , THWAITES C. J.
Published: July 2002

Ten single-sire mating groups of 13 Horro ewes per ram were

used to study the effects of mating on liveweight, body condition and

scrotal circumference changes and their relationships with level of

sexual activity at different stages of the joining period, and

effects of sexual activity and pre-joining liveweight and scrotal

circumference on fertility. Mating had adverse effects on liveweight,

body condition and scrotal circumference. There was a tendency for

mean daily liveweight loss to increase with increasing number of

services during the period of peak sexual activity and over the whole

joining period. Changes in scrotal circumference were

non-significantly correlated with sexual activity. Pre-joining

liveweight and scrotal circumference had no significant effects on

the proportion of ewes served, rate of return to first service and

fertility. High losses of liveweight and scrotal circumference were

observed during the stage of peak sexual activity, and it could be

suggested that more supplementary feed should be provided to working

rams at this stage, especially if the ewe[ratio ]ram ratio is to be

increased. There is no significant benefit to be gained by increasing

ram mating weight and scrotal circumference from 30 kg and 27 cm to

40 kg and 31 cm respectively in Horro sheep.
Morphological dynamics and seedling recruitment in

young swards of three contrasting cultivars of white clover

(Trifolium repens) under continuous stocking with sheep
Authors: FOTHERGILL M. , DAVIES D. A. , DANIEL G. J.
Published: July 2002

Although there has been some recent interest in the morphology
of

individual white clover plants

within established mixed swards under sheep grazing, there is little

information available on the

morphological changes taking place during the critical first 3 years of

sward development.

Undamaged white clover plants were sampled from an experiment at Plas

Gogerddan, Ceredigion,

comparing three contrasting white clover cultivars, sown with a common

companion ryegrass

cultivar, under continuous stocking with sheep. Turves (250 × 250
mm),

from which individual plants

were carefully extracted, were taken every month during 1990–91

(years 2 and 3 after sowing). Each

plant was described in detail by assessing a range of morphological

characters. Information was also

gathered from each quadrat on the degree of flowering and seedling recruitment.

There were clear

seasonal variations in plant size and complexity with an increase in the

number of simple, unbranched

plants over the winter/spring period, which became the dominant plant

type by June. During the later

part of each year, the reverse was true. Characters associated with plant

size also decreased over the

winter period, followed by recovery during the ensuing summer. However
the

recovery was not

complete and there was a strong general trend towards an increased proportion

of less complex plants

of reduced size over the 2 years. As plant size fell, plant number increased

and morphological

differences between cultivars diminished. By autumn of the second year

(third year after sowing) the

mean plant size reached a critical level with further stolon loss resulting

in large scale plant death.

Over the 2-month period August–October 1991, plant number fell by

60% and resulted in a reduction

in stolon abundance of 76%; a true clover crash. The seedling data also

suggest that under these

conditions seedling recruitment can be up to one twentieth of that expected

from a conventional

sowing and can play a substantial role in the regeneration of the sward.
Integration of nitrate cover crops into sugarbeet

(Beta vulgaris) rotations. II. Effect of cover crops on

growth, yield and N requirement of sugarbeet
Authors: ALLISON M. F. , ARMSTRONG M. J. , JAGGARD K. W. , TODD A. D.
Published: July 2002

Between 1989 and 1993, 17 experiments tested the

effects of autumn-sown cover crops on the yield,

processing quality and N nutrition of subsequent sugarbeet

crops. Cover crops had no effect on

sugarbeet plant population density or pesticide requirement.

In nitrogen response experiments, the

mean beet yield at the economic optimum was 83 t/ha.

The mean N fertilizer requirement was

96 kg N/ha and the N uptake at maximum yield averaged

180 kg N/ha. Cover crops had no effect

on yield, fertilizer requirement or N uptake. In addition,

cover crops generally had no effect on the

efficiency of N fertilizer use, the mineralization of N

from the soil organic matter nor the amount of

soil mineral nitrogen at sowing or at harvest of the beet

crop. Processing quality was also not affected

by cover crops. The cost of growing a cover crop ranged

from 0 to 50 £/ha. Since these costs cannot

be offset against increases in yields or reduced

fertilizer application rates, cover crops need to be low

cost, i.e. cheap seed and minimal cultivation. Cover

crops using volunteer cereals and weeds or farm-saved

grain that are established with a single stubble-cultivation

should fulfil these criteria.
Cotton responses to different light–temperature regimes
Authors: ROUSSOPOULOS D. , LIAKATAS A. , WHITTINGTON W. J.
Published: July 2002

A series of experiments investigating the interactive effects of
light and temperature on vegetative
growth, earliness, fruiting, yield and fibre properties in three cultivars
of cotton, was undertaken in
growth rooms. Two constant day/night temperature regimes with a difference
of 4 °C (30/20 and
26/16·5 °C) were used throughout the growing season in combination
with two light intensities (75
and 52·5 W m−2).

The results showed that significant interactions occurred for most of
the characters studied.
Although the development of leaf area was mainly temperature-dependent,
plants at harvest had a
larger leaf area when high temperature was combined with low rather than
with high light intensity.
Leaf area was least in the low temperature–low light regime. However,
the plants grown under the
high temperature–low light combination weighed the least.

Variations in the number of nodes and internode length were largely
dependent on temperature
rather than light. Light did, however, affect the numbers of branches,
sympodia and monopodia. The
first two of these were highest in the high light–high temperature
regime and the third in the low
light–low temperature regime.

All other characters, except time to certain developmental stages and
fibre length, were reduced at
the lower light intensity. Variation in temperature modified the light
effect and vice versa, in a
character-dependent manner. More specifically, square and boll dry weights,
as well as seed cotton
yield per plant, were highest in high light combined with low temperature,
where the most and
heaviest bolls were produced. But flower production was favoured by high
light and high
temperature, suggesting increased boll retention at low temperature, especially
when combined with
low light. Low temperature and high light also maximized lint percentage.

Fibres were shortest in the high temperature–high light regime,
where fibre strength, micronaire
index and maturity ratio were at a maximum. However, the finest and the
most uniform fibres were
produced when high light was combined with low temperature.

Cultivar differences were significant mainly in leaf area and dry matter
production at flowering.
Characterization of a collection of Aeschynomene histrix in subhumid Nigeria
Authors: MERKEL U. , PETERS M. , TARAWALI S. A. , SCHULTZE-KRAFT R. , BERNER D. K.
Published: July 2002

A collection of 64 accessions of the South American pasture legume Aeschynomene histrix Poiret was
characterized in 1995 at Ibadan in south-west Nigeria in order to test the potential of the accessions
as forage plants in subhumid areas and as a trap crop for the parasitic plant Striga hermonthica (Del.)
Benth. All accessions had a low biomass production during the first 8 weeks after sowing but soon
variations in the collection became apparent. Morphologically, accessions could be classified as
having prostrate, decumbent, semi-erect and erect growth habit. The semi-erect to erect accessions
grew vigorously and had high dry matter yields. The most frequent disease was Rhizoctonia foliar
blight, for which, in general, prostrate accessions had a higher severity. In contrast, plants with semi-
erect to erect growth habit were more susceptible to a wilting disease probably caused by Fusarium
spp. With an average crude protein content of 16% and 48-h in sacco dry matter and protein
digestibilities of c. 50%, fodder quality of 13-week-old plants was similar to that of other tropical
forage legumes. As a result of a laboratory experiment to test the potential of A. histrix to act as a
trap crop for Striga hermonthica, 13 accessions showing a significant influence on in vitro Striga
hermonthica seed germination were identified. Twenty promising accessions were selected for further
evaluation. These accessions showed good biomass production and/or high tolerance to diseases
and/or significant influence on Striga hermonthica seed germination. Such material has the potential
to contribute to both livestock-forage and improved fallow systems with the aim of increasing the
sustainability of agricultural production in West Africa.
GENETIC AND ENVIRONMENTAL INFLUENCES ON ALCOHOL USE: DF ANALYSIS OF NLSY KINSHIP DATA
Authors: BUSTER MAURY A. , RODGERS JOSEPH LEE
Published: July 2002

Research designs to study alcohol use and abuse have included twin, adoption and family history/high risk studies. Results have consistently implied a genetic factor in the aetiology of alcohol abuse. However, less research has been conducted in search of environmental factors. This study uses kinship structure in a large national dataset (the National Longitudinal Survey of Youth) to estimate (using DeFries–Fulker analysis) the extent of the shared genetic, non-shared genetic, shared environmental and non-shared environmental influences on alcohol use. The NLSY kinship sample contained 3890 pairs of cousins, half-siblings, full-siblings and twins between the ages of 14 and 21 in the initial year of the survey (1979). Estimates of heritability (h2) and shared environment (c2) were small to moderate for the entire dataset for both light drinking and heavy drinking behaviour, with h2 estimates slightly higher in each case. Non-shared genetic measures of self-esteem and locus of control accounted for a significant portion of the remaining variance in heavy drinking behaviour. Race and gender patterns showed c2 and h2 estimates that were also small to moderate for both light and heavy drinking behaviour. Significant non-shared effects were found for the White group for heavy drinking behaviour, and for male pairs for both heavy and light drinking behaviour. Additionally, implications and future directions are discussed.
Development and application of confocal scanning laser microscopy methods for studying the distribution of fat and protein in selected dairy products
Authors: AUTY MARK A. E. , TWOMEY MYRA , GUINEE TIMOTHY P. , MULVIHILL DANIEL M.
Published: July 2002

Confocal scanning laser microscopy (CSLM) methods were developed to identify fat and protein in cheeses, milk chocolate and milk powders. Various fluorescent probes were assessed for their ability to label fat or protein in selected food products in situ. Dual labelling of fat and protein was made possible by using mixtures of probes. Selected probes and probe mixtures were then used to study (a) structure development of Mozzarella cheese during manufacture and ripening, and (b) the distribution of fat and protein in milk chocolate made with milk powders containing varying levels of free fat. Microstructural changes in the protein and fat phases of Mozzarella cheese were observed at each major step in processing. Aggregation of renneted micelles occurred during curd formation; this was followed by amalgamation of the para-casein into linear fibres during plasticization. Following storage, the protein phase of the Mozzarella became more continuous; entrapping and isolating fat globules. Chocolate made with a high free-fat spray-dried powder blend showed a homogeneous fat distribution, similar to that of chocolate made with roller-dried milk. Chocolate made with whole milk powder containing 10 g free fat/100 g fat showed a non-homogeneous fat distribution with some fat occluded within milk protein particles. These differences in fat distribution were related to Casson yield value and Casson viscosity of the chocolates.
Immune modulation in suckling rat pups by a growth factor extract derived from milk whey
Authors: PENTTILA IRMELI A. , ZHANG MIN F. , BATES EDNA , REGESTER GEOFFREY , READ LEANNA C. , ZOLA HEDDY
Published: July 2002

Oral tolerance to foreign enteral antigens is not fully developed in early neonatal life. Epidemiological evidence supports a role for maternal milk in the development of immune responses, including oral tolerance. Formula fed infants have an increased susceptibility to food allergy and the later development of autoimmune disease. This may relate to the lack in infant formula of growth factors found in maternal milk. Bovine milk contains proteins, growth factors and cytokines. Various studies have outlined the immune modulating potential of bovine milk-derived products. Fractionated whey extracts have therapeutic potential in disease states where there is an excessive inflammatory reaction, and disease preventive potential for infants who are not breast-fed. We have shown that daily oral administration of a growth factor-enriched fraction from milk whey to naturally suckling rat pups between days 4–9 postnatal can down-regulate immune activation to a specific orally administered food antigen, ovalbumin, assessed by lymphocyte proliferation. In addition, non-specific down-regulation in the intestine was observed as assessed by the expression of MHC I. Treatment of rat pups with whey extract at the time of oral sensitisation to ovalbumin also resulted in an increased secretion of TGF-β into the culture supernatant of spleen cells incubated with specific antigen. TGF-β is an immuno-down-regulatory cytokine involved in tolerance induction. Immune modulation by extracts derived from milk whey could be of potential benefit for formula-fed and pre-term infants in reducing susceptibility to inappropriate activation to food antigens.
Nutritional requirements of Leuconostoc mesenteroides subsp.

mesenteroides and subsp. dextranicum for growth in milk
Authors: BELLENGIER PASCALE , RICHARD JEAN , FOUCAUD CATHERINE
Published: July 2002

Growth of Leuconostoc mesenteroides in milk was
studied with respect to
the proteinase and peptidase activities of the strains and their nutritional

requirements. Ln. mesenteroides grew poorly in milk
since none of the 14 strains studied exceeded 5×108
cfu/ml at the end of growth. Few strains displayed
proteinase activity, and this did not contribute much to growth. The pattern
of
peptidase activities varied with the strain. Nitrogen starvation and a
high
requirement for Mn2+ were involved in the cause of growth
deficiencies. Addition of amino acids, 50 mg Mg2+/l and

0·08–0·49 mg Mn2+/l stimulated growth
of most
leuconostoc strains up to 5×108 cfu/ml.
Addition of 5 g glucose/l to milk containing
amino acids, Mg2+ and Mn2+ or yeast extract
stimulated the growth of seven and eight strains respectively up to 109

cfu/ml. No growth advantage was found in a N2
atmosphere. However, the addition of small amounts of Mn2+
to milk suppressed the
inhibitory effect of aeration on the growth of Ln. mesenteroides

UD23, suggesting a protective role of Mn2+ against O2
toxicity.
Subclinical mastitis assessed by deviations in
milk yield and electrical resistance
Authors: SHOSHANI EZRA , BERMAN AMIEL
Published: July 2002

Concurrent falls in milk production and electrical
resistance of composite
milk were examined in Israeli Holstein cows. The cows were
milked three times a day
by a system that recorded yield and the lowest electrical
resistance in the composite
milk from the four glands. The study included two groups:
cows that experienced on
day 0 a decline in resistance and milk production
[ges ]20% from the mean of the
previous 9 d (62 cows, case group) and cows that
experienced no such episodes over
9 d before and after a fixed day (118 cows, control
group). Bacteriological status and
somatic cell count (SCC) or California mastitis test
scores were assessed on the fixed
day in the control group, and on days 0, 1 and 2 in the
case group. California mastitis
test scores greater than 2 and SCC thresholds of
5×105 cells/ml were used to create
two classes of leucocytosis. There was no statistically
significant difference between
the two groups in frequency distributions of pathogens
and their types: in 30% of
cows infection was not detected, 33% were infected by
major pathogens (95% of
which were Staphylococcus aureus), and
53·5% by minor pathogens (80% Micrococcus
spp.). Cows in the case group had lower milk production
during the 8 d following day
0. Mean electrical resistance was lower in infected
cows and particularly in cows
infected by Staph. aureus. High leucocytosis was
associated with reduced electrical
resistance in both groups, and was found in 93% of cows in
the case group v. 25%
in the control group. The results suggest that falls in
electrical resistance of milk
and in milk production were not linked to a specific
pathogen, and were followed by
3–8 d of reduced milk production and electrical
resistance. The study suggests that
there are episodic aggravations in mammary health that
do not evolve into clinical
mastitis but may induce significant losses in milk yield
and quality.
Seasonal and lactational influences on bovine milk composition in
New Zealand
Authors: AULDIST MARTIN J. , WALSH BRIAN J. , THOMSON NORMAN A.
Published: July 2002

This study was designed to evaluate the respective influences of
stage of
lactation (SOL) and time of year on the seasonal variation in milk composition
for
pasture-fed dairy cows in New Zealand. Four herds of ∼20 Friesian cows
were used,
one herd calving in a 6 week period beginning in each of January, April,
July and
October. Cows grazed rye-grass–white clover pasture only, except
during June when
all cows received supplementary pasture silage. Milk samples were collected
from
each cow in milk on four occasions during the year (September, December,
March
and June), to give a total of three samples per cow (early, mid and late
lactation;
about 30, 120 and 210 d respectively after calving). Samples were analysed
for a
detailed range of components. Concentrations of many milk components (e.g.
total
protein, fat, casein and whey protein) increased as lactation progressed;
the extent
of these increases depended on the time of year. These results indicated
that
spreading calving throughout the year would lessen seasonal variations
in the gross
composition of milk supplied to factories, leading to a more even distribution
of
product yield across the year. Despite this, variations in some important

manufacturing properties were affected by time of year but not by SOL.
Ratios of
protein[ratio ]fat and casein: whey protein were not significantly affected
by SOL, but
were affected by time of year. The solid fat content of milk was also affected
by time
of year. Seasonal variations in the manufacturing properties of milk may
be reduced
but not eliminated by changing the time of calving.
Physicochemical, molecular and immunological characterization of
camel calf rennet: a comparison with buffalo rennet
Authors: ELAGAMY ELSAYED I.
Published: July 2002

Camel calf rennet (CCR) and buffalo calf rennet (BCR) were prepared
from dried abomasa to study their physicochemical properties and electrophoretic
behaviour and to carry out an immunological characterization of the rennet proteins.
CCR was more thermostable than BCR. The milk clotting activity of both rennets
increased as pH decreased. The optimum temperatures for CCR and BCR were 50
and 45 °C respectively. CCR was more sensitive to increased CaCl2 in milk than BCR.
Addition of NaCl to milk in the range 0–100 g/l resulted in a marked decrease in the
clotting activity of both rennets. When the rennets were treated with acetone, the
activity of BCR was completely destroyed, but that of CCR was unaffected. The
proteolytic activity of CCR was higher than that of BCR and pepsin towards both
camel and cows' milk caseins at pH 6·0. SDS-PAGE electrophoretic patterns of CCR
and BCR proteins gave two major bands with molecular masses estimated as 52 and
39 kDa for CCR and 50 and 35 kDa for BCR. Immunodiffusion and immunoelectrophoresis
using anti-CCR serum demonstrated immunological cross reactivity
between CCR and BCR.
Base pressure prediction in bluff-body potential-flow models
Authors: YEUNG W. W. H. , PARKINSON G. V.
Published: July 2002

In a recent study by Yeung & Parkinson (1997), a wake width was proposed which
allowed the bluff-body potential-flow model by Parkinson & Jandali (1970) to be
extended to include the flow around an oblique flat plate. By incorporating this wake
width in the momentum equation originally derived by Eppler (1954) for separated
flow, the drag of the plate is related to its inclination and base pressure through
a simple analytical condition. It allows the base pressure, which is usually treated
as an empirical input, to be determined theoretically and thus the model becomes
self-contained. Predictions of the base pressure, drag and width of wake are found
to be in reasonable agreement with the experimental data. When applied to the
symmetrical flow around a wedge of arbitrary vertex angle, similar agreement with
experimental measurements is obtained as well. It is also demonstrated that this
condition is compatible with the free-streamline models by Wu (1962) and Wu &
Wang (1964) such that the corresponding predictions are in good agreement with
experiment.
Wake formation around islands in oscillatory laminar shallow-water flows. Part 2.
Three-dimensional boundary-layer modelling
Authors: STANSBY PETER K. , LLOYD PETER M.
Published: July 2002

A three-dimensional numerical model for shallow-water flow with the assumption of
hydrostatic pressure has been applied to oscillatory laminar flow around a conical
island of small side slope (8°). The model is (mainly) second-order accurate in space
and time with advection in conservation form. This form of model is effectively
a boundary-layer solution with imposed depth-integrated continuity. To reproduce
experimental conditions particular care was required for boundary conditions to
account for seiching in the flume. The model predicted the wide range of wake
structures observed experimentally and described in Part 1 (Lloyd, Stansby & Chen
2001), from symmetric with weak vortex pairing to complex vortex shedding.
Passive-scalar wake behind a line source in grid turbulence
Authors: LIVESCU D. , JABERI F. A. , MADNIA C. K.
Published: July 2002

The structure and development of the scalar wake produced by a single line source are
studied in decaying isotropic turbulence. The incompressible Navier–Stokes and the
passive-scalar transport equations are solved via direct numerical simulations (DNS).
The velocity and the scalar fields are generated by simulating Warhaft's (1984)
experiment. The results for mean and r.m.s. scalar statistics are in good agreement
with those obtained from the experiment. The structure of the scalar wake is examined
first. At initial times, most of the contribution to the scalar variance is due to the
flapping of the wake around the centreline. Near the end of the turbulent convective
regime, the wake develops internal structure and the contribution of the flapping
component to the scalar variance becomes negligible. The influence of the source size
on the development of the scalar wake has been examined for source sizes ranging
from the Kolmogorov microscale to the integral scale. After an initial development
time, the half-widths of mean and scalar r.m.s. wakes grow at rates independent of the
source size. The mixing in the scalar wake is studied by analysing the evolution of the
terms in the transport equations for mean, scalar flux, variance, and scalar dissipation.
The DNS results are used to test two types of closures for the mean and the scalar
variance equations. For the time range simulated, the gradient diffusion model for
the scalar flux and the commonly used scalar dissipation model are not supported by
the DNS data. On the other hand, the model based on the unconditional probability
density function (PDF) method predicts the scalar flux reasonably well near the end
of the turbulent convective regime for the highest Reynolds number examined. The
scalar source size does not significantly influence the models' predictions, although
it appears that the time-scale ratio of mechanical dissipation to scalar dissipation
approaches an asymptotic value earlier for larger source sizes.
Stability of inviscid shear flow over a flexible boundary
Authors: MILES JOHN
Published: July 2002

The stability of an inviscid flow that comprises a thin shear layer and a uniform
outer flow over a flexible boundary is investigated. It is shown that the flow is
temporally unstable for all wavenumbers. This instability is either Kelvin–Helmholtz-like or induced by the phase shift across the critical layer. The threshold of absolute
instability is determined in the form F = F∗(1 + Cεn) for ε [Lt ] 1, where F (a Froude
number) and ε are, respectively, dimensionless measures of the flow speed and the
shear-layer thickness, F∗ is the limiting value of F for a uniform flow, C < 0 and n = 1
in the absence (as for a broken-line velocity profile) of a phase shift across the critical
layer, and C > 0 and n = 2/3 in the presence of such a phase shift. Explicit results
are determined for an elastic plate (and, in an Appendix, for a membrane) with a
broken-line, parabolic, or Blasius boundary-layer profile. The predicted threshold for
the broken-line profile agrees with Lingwood & Peake's (1999) result for ε [Lt ] 1, but
that for the Blasius profile contradicts their conclusion that the threshold for ε ↓ 0 is a ‘singular and unattainable limit’.
Effect of membrane bending stiffness on the deformation of capsules in simple shear flow
Authors: POZRIKIDIS C.
Published: July 2002

The effect of interfacial bending stiffness on the deformation of liquid capsules
enclosed by elastic membranes is discussed and investigated by numerical simulation.
Flow-induced deformation causes the development of in-plane elastic tensions
and bending moments accompanied by transverse shear tensions due to the non-infinitesimal
membrane thickness or to a preferred configuration of an interfacial
molecular network. To facilitate the implementation of the interfacial force and torque
balance equations involving the hydrodynamic traction exerted on either side of the
interface and the interfacial tensions and bending moments developing in the plane of
the interface, a formulation in global Cartesian coordinates is developed. The balance
equations involve the Cartesian curvature tensor defined in terms of the gradient of
the normal vector extended off the plane of the interface in an appropriate fashion.
The elastic tensions are related to the surface deformation gradient by constitutive
equations derived by previous authors, and the bending moments for membranes
whose unstressed shape has uniform curvature, including the sphere and a planar
sheet, arise from a constitutive equation that involves the instantaneous Cartesian curvature
tensor and the curvature of the resting configuration. A numerical procedure
is developed for computing the capsule deformation in Stokes flow based on standard
boundary-element methods. Results for spherical and biconcave resting shapes resembling
red blood cells illustrate the effect of the bending modulus on the transient
and asymptotic capsule deformation and on the membrane tank-treading motion.
An experiment on two aspects of the interaction between strain and vorticity
Authors: ANDREOTTI BRUNO , DOUADY STÉPHANE , COUDER YVES
Published: July 2002

Presented here are two results concerning the interaction between vorticity and
strain. Both are obtained experimentally by investigating the hyperbolic flow created
in Taylor's four-roll mill. It is first shown that this pure straining flow becomes
intrinsically unstable through a supercritical bifurcation to form an array of counter-rotating
vortices aligned in the stretching direction. The dimensionless parameter characterizing the flow is the internal
Reynolds number Re = γΔ2/v based on the
velocity gradient γ and on the gap between the rollers Δ, and the threshold value
is Rec = 17. Near the threshold, the transverse velocity profiles of these vortices are
in excellent agreement with those predicted by the theory of Kerr & Dold (1994) in
the case of an infinite hyperbolic flow. A second result is obtained at high Reynolds
number. Measurements of the velocity profile in the direction parallel to the vortices
show that the velocity gradient (the stretching) is systematically weaker inside the
vortices than elsewhere. This demonstrates experimentally the existence of a negative
feedback of rotation on stretching. This effect is ascribed to the two-dimensionalization
due to the vortex fast rotation. An implication of these results for turbulent flows is
a nonlinear limitation of the vorticity stretching, an effect characterized recently by
Ohkitani 1998.
Drag reduction by polymer additives in a turbulent pipe
flow: numerical and laboratory experiments
Authors: DEN TOONDER J. M. J. , HULSEN M. A. , KUIKEN G. D. C. , NIEUWSTADT F. T. M.
Published: July 2002

In order to study the roles of stress anisotropy and of elasticity in
the mechanism
of drag reduction by polymer additives we investigate a turbulent pipe flow of a
dilute polymer solution. The investigation is carried out by means of direct
numerical
simulation (DNS) and laser Doppler velocimetry (LDV). In our DNS two different
models are used to describe the effects of polymers on the flow. The first is a
constitutive equation based on Batchelor's theory of elongated particles
suspended
in a Newtonian solvent which models the viscous anisotropic effects caused by the
polymer orientation. The second is an extension of the first model with an elastic
component, and can be interpreted as an anisotropic Maxwell model. The LDV
experiments have been carried out in a recirculating pipe flow facility in which we
have used a solution of water and 20 w.p.p.m. Superfloc A110. Turbulence statistics
up to the fourth moment, as well as power spectra of various velocity components,
have been measured. The results of the drag-reduced flow are first compared with
those of a standard turbulent pipe flow of water at the same friction velocity at a
Reynolds number of Reτ≈1035. Next the results of the
numerical simulation and
of the measurements are compared in order to elucidate the role of polymers in the
phenomenon of drag reduction. For the case of the viscous anisotropic polymer model,
almost all turbulence statistics and power spectra calculated agree in a qualitative
sense with the measurements. The addition of elastic effects, on the other hand, has
an adverse effect on the drag reduction, i.e. the viscoelastic polymer model shows
less drag reduction than the anisotropic model without elasticity. Moreover, for
the case
of the viscoelastic model not all turbulence statistics show the right behaviour. On
the basis of these results, we propose that the viscous anisotropic stresses
introduced by extended polymers play a key role in the mechanism of drag
reduction by polymer additives.
Turbulent convection into a linearly stratified

fluid: the generation of ‘subsurface anticyclones’
Authors: NARIMOUSA SIAVASH
Published: July 2002

Penetrative turbulent convection from a localized circular

top source into a rotating,

linearly stratified ambient fluid of strength N has

been investigated in a laboratory

tank. Initially, the induced three-dimensional convective flow

penetrated rapidly into

the stratified water column until it reached an equilibrium depth

at which the

convective flow began to propagate radially outward. At this stage,

the usual cyclonic

vortices were generated around the convection source at the edge

of the radially propagating flow. Soon after, a thin ‘subsurface

anticyclone’ was formed at the level

of equilibrium depth beneath the convection source. Later, this

anticyclone dominated

the central part of the convective regime and did not allow

new cyclones to be injected

into the system. After reaching its maximum mean diameter

Da/R

≈10(R0;R)2/3 and

swirl velocity va

≈(B0R)1/3,

an anticyclone became unstable and split into two new

vortices that left the area beneath the source, allowing a new

anticyclone to form at its original place (here,

R0,R

=(B0/f3R2)

1/2 is the Rossby number based on R the

radius of the source, B0 is the surface

negative buoyancy flux, and f is the Coriolis

parameter). These observations provide crucial evidence that many

of the ‘subsurface

anticyclonic’ vortices detected in the stratified pycnocline

of the central Arctic Ocean

are indeed generated as a result of convective processes occurring

in this region.
A numerical study of the evolution and structure

of a turbulent shear layer under a free surface
Authors: TSAI WU-TING
Published: July 2002

Results from direct numerical simulations of an unsteady

turbulent shear layer with

a free surface are presented. The emphasis is on the interaction

dynamics of the

free surface with the coherent vortices in the underlying turbulent

shear flow as well

as the resulting free-surface signatures. Instantaneous vortex lines

and isosurfaces

of enstrophy indicate that coherent horseshoe vortical structures

emerge from the

random initial vorticity field. These horseshoe vortices impinge,

break and reconnect

onto the free surface, and then appear as two vortex connections

with opposite signs

on the surface. The two identified vortical structures correspond to

‘splatting’ and

‘swirling’ events, which have been observed in other

experiments and simulations of

free-surface/turbulence flows. Though free-surface depressions

form near the vertical-vorticity centres in the connection processes,

only a low correlation (≈50% to 60%)

is found between the free-surface roughness (vertical deformation) and

the connected

normal vorticity. On the other hand, the free-surface curvatures and

the tangential

free-surface vorticities are better correlated (≈80% to 90%). The

balance of enstrophy

and the vorticity transport show that stretching and viscous dissipation

along the

direction of the vorticity vector dominate the vortex dynamics near

the free surface.

These two transport mechanisms are found to be responsible for the

cancellation

of the spanwise vorticity of the horseshoe-vortex heads and the

annihilation of the surface-connected normal vorticities.
Matched asymptotics for two-dimensional planing hydrofoils with spoilers
Authors: FRIDMAN G. M.
Published: July 2002

The purpose of the paper is to demonstrate the effectiveness of
the matched asymptotic
expansions (MAE) method for the planing flow problem. The matched asymptotics,

taking into account the flow nonlinearities in those regions where they
are most
pronounced (i.e. in the vicinity of the edges), are shown to significantly
extend the
range where the linear theory gives good results. Two model problems are
used:
the planing flat plate with a spoiler on the trailing edge and the curved
planing foil.
Asymptotic solutions obtained by the MAE method are compared with those
obtained
using linear and exact nonlinear theories. Based on the results, the asymptotic
solution
to the planing problem under the gravity is proposed.
Kinetic theory for a vibro-fluidized bed
Authors: KUMARAN V.
Published: July 2002

The velocity distribution function for a two-dimensional vibro-fluidized
bed of
particles of radius r is calculated using asymptotic analysis
in
the limit where (i) the
dissipation of energy during a collision due to inelasticity or between
successive collisions
due to viscous drag is small compared to the energy of a particle and (ii)
the
length scale for the variation of density is large compared to the particle
size. In this
limit, it is shown that the parameters
εG=rg/T0 and

ε=U20/T0[Lt ]1,
and
ε and εG are
used as small parameters in the expansion. Here, g is the acceleration
due to gravity,
U0 is the amplitude of the velocity of the
vibrating surface and T0 is the leading-order

temperature (divided by the particle mass). In the leading approximation,
the dissipation
of energy and the separation of the centres of particles undergoing a binary

collision are neglected, and the system is identical to a gas of rigid
point particles
in a gravitational field. The leading-order particle number density is
given by the
Boltzmann distribution
ρ0∝exp(−gz/T0,
and the velocity
distribution function is given by the Maxwell–Boltzmann distribution

f(u)=(2πT0)−1exp
[−u2/(2T0)],
where
u is the particle velocity. The temperature cannot be determined
from the leading
approximation, however, and is calculated by a balance between the rate
of input of
energy at the vibrating surface due to particle collisions with this surface,
and the rate
of dissipation of energy due to viscous drag or inelastic collisions. The
first correction
to the distribution function due to dissipative effects is calculated using
the moment
expansion method, and all non-trivial first, second and third moments of
the velocity
distribution are included in the expansion. The correction to the density,
temperature
and moments of the velocity distribution are obtained analytically. The
results show
several systematic trends that are in qualitative agreement with previous
experimental
results. The correction to the density is negative at the bottom of the
bed, increases
and becomes positive at intermediate heights and decreases exponentially
to zero as
the height is increased. The correction to the temperature is positive
at the bottom
of the bed, and decreases and assumes a constant negative value as the
height is
increased. The mean-square velocity in the vertical direction is greater
than that in
the horizontal direction, thereby facilitating the transport of energy
up the bed. The
difference in the mean-square velocities decreases monotonically with height
for a
system where the dissipation is due to inelastic collisions, but it first
decreases and
then increases for a system where the dissipation is due to viscous drag.