bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of hitch-hiking on neutral genealogies
Authors: BARTON N. H.
Published: July 2002

When a favourable mutation sweeps to fixation, those genes initially
linked to it increase in
frequency; on average, this reduces diversity in the surrounding region
of the genome. In the first
analysis of this ‘hitch-hiking’ effect, Maynard-Smith and Haigh
(1974) followed the increase of the
neutral allele that chanced to be associated with the new mutation in the
first generation, and
assumed that the subsequent increase was deterministic. Later analyses,
based on either coalescence
arguments, or on diffusion equations for the mean and variance of allele
frequency, have also
made one or both of these assumptions. In the early generations, stochastic
fluctuations in the
frequency of the selected allele, and coalescence of neutral lineages,
can be accounted for correctly
by following relationships between genes conditional on the number of copies
of the favourable
allele. This analysis shows that the hitch-hiking effect is increased because
an allele that is destined
to fix tends to increase more rapidly than exponentially. However, the
identity generated by the
selective sweep has the same form as in previous work,
h[r/s]
(2 Ns)−2r/s,
where h[r/s] tends to 1
with tight linkage. This analysis is extended to samples of many genes;
then, genes may trace back
to several families of lineages, each related through a common ancestor
early in the selective
sweep. Simulations show that the number and sizes of these families can
(in principle) be used to
make separate estimates of r/s and Ns.
Co-adaptation of pheromone production and behavioural
responses in Drosophila melanogaster males
Authors: SUREAU GILLES , FERVEUR JEAN-FRANÇOIS
Published: July 2002

In Drosophila melanogaster, male courtship behaviour is genetically controlled and is influenced by
sex pheromones. 7-tricosene (7-T) induces a dose-dependent inhibition of male–male courtship,
whereas 7,11-dienes stimulate male courtship of females. There is a geographical quantitative
variation in the production of two predominant male hydrocarbons, 7-T and 7-pentacosene (7-P).
We have previously found that 7-P, the main hydrocarbon from males of West African strains,
stimulates males that mainly produce 7-T. Using both ‘natural’ and genetically engineered strains,
we find that genetic factors coding for low levels of 7-P in males have co-evolved with factor(s)
coding for male responses to high levels of 7-P. These two phenotypes are coded by factors on
different chromosomes: the intraspecific polymorphism for the production of 7-T and 7-P is largely
controlled by chromosome 2, whereas the variation in courtship towards 7-P-rich males is largely
controlled by chromosome 3. The polymorphism of male courtship towards 7-P-rich males shows
no correlation with the variation in male responses to female flies.
LICENSING, CENSORSHIP, AND RELIGIOUS ORTHODOXY IN EARLY
STUART ENGLAND
Authors: MILTON ANTHONY
Published: July 2002

This article engages with recent work on the nature of religious

censorship in the early
Stuart period that has emphasized that the government possessed neither

the power nor the will to
control systematically what was written. It is argued here, instead,
that there is evidence of attempts
to control the presses' output of religious materials during the
Laudian period and earlier, by all parties
within the Church of England. Nevertheless, the intention here is
not to revive a simplistic view of
government ‘control’, but rather to study the means by
which licensers could exert an influence over
what would be printed with an aura of mainstream legitimacy. Texts
were often interfered with by
official licensers with a variety of motives. Interference might
sometimes be essentially ‘benign’,
conferring legitimacy on marginal works by massaging their contents,
or texts might be modified in
order to make their authors appear to endorse the views of their
opponents. The issue of whether it was
practically possible to publish work clandestinely is here seen to
be something of a red herring, since
by publishing in this illicit fashion authors were effectively
resigning their right to be considered as
spokesmen of the orthodox mainstream. It is the control and
manipulation of the licensing process
which emerges as one important means by which the religious middle ground
was defined and
controlled in the early Stuart period.
JOHN LOCKE AND THE RYE HOUSE PLOT
Authors: MILTON PHILIP
Published: July 2002

In recent years it has become widely accepted that John Locke was involved, perhaps
deeply involved, in the Rye House plot of 1682–3. This article takes another look at the evidence for
this, and in particular at Richard Ashcraft's claims that he was closely involved with many of the
plotters, that he attended some of their meetings, that his letters contain coded references to their
activities, and that he hastily left London immediately they realized they had been betrayed. These
claims are found wanting. Locke was probably aware that Shaftesbury and others were planning (or
at least talking about) an insurrection, but there is little to indicate that he was directly involved. An
analysis of his movements during the autumn of 1682 suggests if anything that he was deliberately
keeping out of the way. There is even less reason for thinking that he was involved in plans to
assassinate Charles II.
WILLIAM LOVETT AND THE NATIONAL ASSOCIATION FOR THE
POLITICAL AND SOCIAL IMPROVEMENT OF THE PEOPLE
Authors: STACK DAVID
Published: July 2002

This article examines the isomorphic connections between the scientific and political
ideas of William Lovett and the National Association for the Political and Social Improvement of the
People. It demonstrates that, far from being a mere coincidental device, distinct from his politics,
Lovett's scientific ideas helped shape the internal structure of his political radicalism. The same was
also true of the National Association more generally. Concepts and assumptions derived from
phrenology and physiology served the heuristic function of stimulating the construction of analogous
systems which directed and conditioned the version of political radicalism which Lovett and the
National Association propagated. This suggests that in the mid-nineteenth century the importance of
the organic sciences was more politically subtle than previously thought and that a reconciliation of the
ideas of George Combe with political radicalism was possible. This insight is compatible with recent
historiographical trends, and opens up new vistas for the study of science in radicalism.
Measurement of protein turnover in the small intestine

of lambs. 1. Development of an experimental model
Authors: NEUTZE S. A. , GOODEN J. M. , ODDY V. H.
Published: July 2002

The objective of this study was to develop an experimental model
to

measure both fractional and

absolute rates of protein synthesis in the small intestine of lambs. Six
male

castrate lambs (∼6 months

old, mean liveweight 26 kg) were offered, via continuous feeders,

900 g/day lucerne chaff. They were

prepared with catheters in the cranial mesenteric vein (CMV), femoral artery

(FA), jugular vein and

abomasum, and a blood flow probe around the CMV. Cr-EDTA (0·139
mg Cr/ml,

∼0·2 ml/min) was infused abomasally for 24 h and

L-[2,6-3H]phenylalanine (Phe)

(441±33·8 μCi into the

abomasum) and L-[U-14C]phenylalanine

(43·9±4·08 μCi into the jugular) were also infused
during

the last 8 h. Blood from the CMV and FA was sampled during isotope infusions.

At the end of infusions, lambs were killed and tissue and digesta samples

removed from four sites along the small intestine (SI). Transfers of labelled

and unlabelled Phe were measured between SI tissue, its lumen

and blood, enabling both fractional and absolute rates of protein synthesis

and gain to be estimated. The total SI protein pool was 84

(±1·7) g and fractional gain rate was 7·5

(±5·5)% per day. Mean protein synthesis and fractional synthesis

rates (FSR) were calculated from the mean retention of

14C and 3H in SI tissue. FSR tended to increase

caudally along the SI (although P > 0·05). The choice
of

free Phe pool for estimating precursor specific radioactivity (SRA) for

protein synthesis had a significant effect on FSR. Assuming that tissue
free

Phe SRA represented precursor SRA gave a mean FSR of 129 (±24)%
per day.

Corresponding estimates for free Phe SRA in the FA and CMV were

20 (±1·8) and 30 (±3·1)% per day respectively.

The correct value for protein synthesis was therefore

in doubt, although indirect evidence suggested that blood SRA (either FA
or

CMV) may be closest to true precursor SRA. This evidence included (i) comparison

with flooding dose estimates of FSR, (ii) comparison of

3H[ratio ]14C Phe SRA in free Phe pools with this

ratio in SI protein, and (iii) the proportion of SI energy use associated
with

protein synthesis. Advantages of the present experimental

model compared to other methods included (i) measurements of both protein

synthesis and gain, and hence, all components of turnover, (ii) measurement
of

absolute as well as fractional rates of synthesis

and gain, (iii) inclusion of proteins which are synthesised and exported,

and (iv) concurrent measurement of protein synthesis and energy

utilization by the small intestine.
Effect of altering the length of the regrowth interval
in early, mid and late season on the productivity of grass swards
Authors: BINNIE R. C. , KILPATRICK D. J. , CHESTNUTT D. M. B.
Published: July 2002

Over three growing seasons (1989 to 1991) perennial ryegrass swards were
cut at regular 3-week
intervals or changed to a 2, 4, 5, 6, 7, 8 or 9-week regrowth interval in the
early (April to mid-June),
mid (late June to mid-August) or late season (late August to mid-October) at
the Agricultural
Research Institute of Northern Ireland. Fertilizer was applied according to
the length of the regrowth
period to supply the equivalent of 2·2 kg N/ha per day with an
annual rate of 416 kg N/ha.

Lengthening the regrowth interval by a single 6-week interval increased
the annual yield of herbage
DM and digestible organic matter (DOM) from 10·13 to 11·15
and from 6·73 to 7·47 t/ha respectively.
The effect increased with increasing length of regrowth period and was
greatest in the early part of
the season. In swards cut on a regular 3-week regime there was no significant
difference in organic
matter digestibility (OMD) throughout the season (mean 69·4%),
whereas N concentration increased
steadily throughout the season, ranging from 25·6 g/kg DM in April
to 41·8 g/kg DM in October.

During the variable regrowth periods, the greatest response in DM and DOM
yield to increasing
length of regrowth interval was obtained in the early part of the season in
spite of a rapid fall in OMD.
There was little to be gained by lengthening the regrowth interval beyond 6
weeks in mid-season, due
to low and declining herbage OMD. However, in the late season period, the
rate of decline in herbage
OMD tended to decrease after week 5 and so the rate of decline in DOM
accumulation was reduced,
making length of regrowth period in the late season less critical.

The treatments imposed had little effect on yield of herbage N
(range 293–354 kg N/ha).
The use of measurements of soil mineral N in
understanding the response of crops to fertilizer
nitrogen in intensive cropping rotations
Authors: RAHN C. R. , PATERSON C. D. , VAIDYANATHAN L. V.
Published: July 2002

The effects on succeeding crops of nitrogen in residues returned

to the soil of brassica vegetable crops
(Brassica oleracea) were studied on a nitrogen-retentive silt

loam soil at Horticulture Research
International, Kirton, Lincolnshire, UK. A sequence of four crops was
started in 1988 and again in
1989. In the first sequence, two successive cauliflower crops
(Brassica oleracea cv. botrytis L.), crops
1 and 2 in the first year, were followed by Brussels sprouts
(Brassica oleracea cv. Gemmifera D.C.),
crop 3, in the second and spring barley (Hordeum vulgare),
crop 4, in the third year. The second
sequence, started in spring 1989, was on an area adjacent to the first,

but with spring wheat (Triticum aestivum) as crop 4. The
sites followed an unfertilized, 1-year grass ley (1987) or spring barley
(1988)
with 73 and 107 kg N/ha soil mineral nitrogen (SMN, NH4+NO3)

in the 0–90 cm soil profile at the
start of each sequence. The marketable yield of the first cauliflowers

in both sequences increased with
fertilizer nitrogen up to 240 or 300 kg/ha. The response of the
second cauliflower crop to fresh N
declined with increasing amounts of SMN (0–90 cm) at planting, with
no response when SMN
exceeded c. 270 kg N/ha. Crop 3 apparently responded to
fresh N in sequence 1 but not in sequence
2 even though SMN at planting ranged up to c. 400 kg N/ha.

This difference in response was largely
explained by the amount and distribution of SMN in the 0–30 and
30–60 cm layers when the sprouts
were planted. Soil mineral N to 90 cm when the cereals were sown was
only c. 100 kg N/ha, which
did not reflect the large amounts of N applied to the previous
crops. In spite of this, barley yield
without any fresh fertilizer N did vary with the amounts of N applied
to the previous crops. The
results showed that SMN was a useful predictor of fertilizer response in

some, but not all, situations.
To use SMN more generally requires interpretation using dynamic simulation
models.
The influence of dairy cow genetic merit on the direct
and residual response to level of concentrate
supplementation
Authors: FERRIS C. P. , GORDON F. J. , PATTERSON D. C. , MAYNE C. S. , KILPATRICK D. J.
Published: July 2002

Twenty-eight high genetic merit and 32 medium genetic merit Holstein/Friesian dairy cows with
Predicted Transmitting Abilities for milk fat plus protein yield, calculated using 1995 as the base year
(PTA95 fat plus protein) of 43·3 and 1·0 kg respectively, were used in a continuous design, 2 (cow
genotypes)×4 (concentrate proportion in diet) factorial experiment consisting of eight treatments.
Concentrate proportions in the diet were 0·37, 0·48, 0·59 and 0·70 of total dry matter (DM), while the
forage component of the diet was grass silage. Diets were offered ad libitum in the form of a complete
diet. Animals remained on these concentrate regimes for a mean of 84·7 days before completing a
standard 98-day grazing period. At pasture, cows received either 5·0 or 6·0 kg concentrate daily
according to turnout date. There were no significant genotype×nutrition interactions for any of the
variables examined during either the indoor feeding or post-turnout grazing periods (P<0·05).
Outputs of milk, fat, protein and fat + protein were greater for high merit cows than for medium
merit animals (P<0·001). Milk output and milk protein output responses to increasing concentrate
proportion were linear for both cow genotypes (P<0·001), while high merit animals showed a linear
response in terms of milk fat plus protein output (P<0·01) with these responses being statistically
parallel for both merits. High merit cows had a significantly higher DM intake than medium merit
animals (P<0·01). With high merit animals, concentrate proportion had little effect on body tissue
reserves, while medium merit animals showed a tendency for increased condition score and backfat
thickness with increasing concentrate inclusions (P<0·05). In terms of the output of milk and milk
constituents during the grazing period, there were no significant residual effects from winter
concentrate feed rate (P>0·05), while high merit cows continued to have higher outputs of milk and
milk constituents (P<0·001). Body tissue reserves of both genotypes changed little during the
grazing period. It is likely that the higher milk yields of the high merit cows can be attributed both
to their higher DM intakes and their ability to partition a greater proportion of the nutrients
consumed into milk rather than body tissue reserves. Although statistically both high and medium
merit cows responded in a similar manner to an increasing proportion of concentrate in the diet, high
merit cows did exhibit a 49% greater fat plus protein yield response during the indoor period,
compared to animals of medium genetic merit, perhaps hinting at the existence of a
genotype×nutrition interaction.
Effect of dietary tannin and protein concentration on
nematode infection (Trichostrongylus colubriformis)
in lambs
Authors: BUTTER N. L. , DAWSON J. M. , WAKELIN D. , BUTTERY P. J.
Published: July 2002

The aim of this study was to determine whether the inclusion of a condensed tannin (quebracho
tannin, QT) and/or the elevation of dietary protein could reduce Trichostrongylus colubriformis
establishment and existence in the small intestine of lambs. Thirty-six lambs (mean liveweight
32·6±3·9 kg) were randomly allocated to one of six experimental groups, groups 1–5 were parasitized
with a trickle infection of 3000 infective Trichostrongylus colubriformis larvae daily, whilst group 6
remained as uninfected controls. Experimental diets were formulated to contain 222 g CP/kg (high
protein) or 97 g CP/kg (low protein) with or without the inclusion of 50 g QT/kg. All six animal
groups were fed the low protein diet, group 2 fed low protein diet+QT, for one month prior to
infection (groups 1–5). Once nematode eggs were observed in the faeces, diets were abruptly changed
in three experimental groups. Group 1 remained on the low protein diet, group 2 remained on the
low protein+QT diet, group 3 changed to the high protein diet, group 4 changed to the high
protein+QT diet, group 5 changed to the low protein+QT diet and group 6 remained uninfected and
fed the low protein diet. Production, haematological and parasitological parameters were monitored
at regular intervals. Results show that parasitized animals fed the high protein diet achieved growth
rates similar to those of uninfected low protein-fed lambs. Inclusion of dietary QT did not depress
liveweight gain. Total daily faecal egg counts declined after feeding the high protein diet. Inclusion
of QT into the low protein diet also reduced faecal egg counts to similar levels observed in the high
protein-fed lambs. The inclusion of QT into the high protein diet did not further reduce faecal egg
counts. No significant differences in the haematological parameters measured were observed between
infected animals (groups 1–5), suggesting that the beneficial effect of dietary QT in the low protein
diet is unlikely to be mediated through an immune response. These data suggest that the inclusion of
QT in low protein diets may be an alternative to feeding high protein diets to reduce nematode burden
in lambs.
A comparison of N and P inputs to the soil from
fertilizers and manures summarized at farm and catchment scale
Authors: DOMBURG P. , EDWARDS A. C. , SINCLAIR A. H.
Published: July 2002

Use of fertilizers and manures during 1994 were studied at the farm and catchment scale in the largely
agricultural Ythan catchment, north-east Scotland, using farm level census data supplemented by
questionnaire data. Grassland accounted for 40% of the agricultural land, and seven farm types
represented 87% of the total land, having an average size of 90 ha. The average livestock density of
1·2 livestock units/ha was high compared to Scotland as a whole (0·5). Rates of inorganic fertilizer
applied to individual crops in the area corresponded with the national average and current advisory
recommendations. At the catchment scale, most fertilizer N was applied to grassland (47%), whereas
spring crops received the greatest proportion of the fertilizer P (35%). The annual manure production
equated to an average over the catchment of 63 and 16 kg/ha of N and P, respectively. When
calculated for farm types these figures ranged from 27 and 6 kg/ha on ‘cereal’ farms to 384 and
163 kg/ha on ‘pig’ farms. The ratio of applied fertilizer N and P varied from 4[ratio ]1 for ‘general
cropping’ to 10[ratio ]1 for ‘cattle and sheep (lowground)’ farms. There was no significant compensatory
reduction in inorganic fertilizer applications on crops, which also had received manures.
SOCIAL NETWORK IN RELATION TO PLASMA FIBRINOGEN
Authors: HELMINEN ANNELI , RANKINEN TUOMO , VÄISÄNEN SARI , RAURAMAA RAINER
Published: July 2002

Consistent findings about the inverse association of social network
level with coronary heart disease mortality and morbidity suggest the
importance of investigating biological pathways of association. Differences in
plasma fibrinogen level were investigated among middle-aged men with weak and
strong structural and functional social network ties. Men with low scores in
the adequacy of social participation variable (structural) had higher mean
values of plasma fibrinogen than those with high scores. The difference
remained after adjustment for age, smoking and cardiovascular health status
and after possible modifying factors were taken into account, but did not
remain significant after allowing for physical fitness. Men with high scores
in overall support (functional) had higher plasma fibrinogen levels compared
to
the men with low scores. This difference persisted after age and
cardiovascular health status were taken into account but was explained
by smoking. The data suggest that smoking and cardiorespiratory fitness are important mediating or modifying factors between structural
and functional aspects of social network ties and plasma fibrinogen.
CHINESE TRADITIONAL MEDICINE AND ABNORMAL SEX RATIO AT BIRTH IN CHINA
Authors: PENG XIZHE , HUANG JUAN
Published: July 2002

A study of the abnormal sex ratio at birth in China reveals that it is not an entirely new phenomenon that emerged since the 1980s, but is simply more visible at present. Deliberate intervention to determine the sex of children has existed in the past few decades, at least in certain groups. Apart from modern medical methods, traditional Chinese medical practice is shown to be highly accurate in identifying the sex of a fetus. This may lead to sex-selective abortion and an abnormal sex ratio at birth. The possible causes of the abnormal sex ratio at birth include not only the real imbalance due to the disturbance of social factors, but also a spurious one attributable to the under-counting of female births. The real magnitude of the imbalance has been exaggerated by statistical error. The phenomenon is a complicated one reflecting the comprehensive socioeconomic setting. Among these factors, the stage of the fertility transition is one of the most decisive.
Rheological properties of milk gels formed by a combination of rennet and glucono-δ-lactone
Authors: LUCEY JOHN A. , TAMEHANA MICHELLE , SINGH HARJINDER , MUNRO PETER A.
Published: July 2002

The effects of heat treatment of milk, and a range of rennet and glucono-δ-lactone (GDL) concentrations on the rheological properties, at small and large
deformation, of milk gels were investigated. Gels were made from reconstituted skim
milk at 30 °C, with two levels each of rennet and GDL. Together with controls this
gave a total of sixteen gelation conditions, eight for unheated and eight for heated
milk. Acid gels made from unheated milks had low storage moduli (G′) of < 20 Pa.
Heating milks at 80 °C for 30 min resulted in a large increase in the G′ value of acid
gels. Rennet-induced gels made from unheated milk had G′ values in the range
∼ 80–190 Pa. However, heat treatment severely impaired rennet coagulation: no gel
was formed at low rennet levels and only a very weak gel was formed at high levels.
In gels made with a combination of rennet and GDL unusual rheological behaviour
was observed. After gelation, G′ initially increased rapidly but then remained steady
or even decreased, and at long ageing times G′ values increased moderately or
remained low. The loss tangent (tan δ) of acid gels made from heated milk increased
after gelation to attain a maximum at pH ∼ 5·1 but no maximum was observed in
gels made from unheated milk. Gels made by a combination of rennet and GDL also
exhibited a maximum in tan δ, indicating increased relaxation behaviour of the
protein–protein bonds. We suggest that this maximum in tan δ was caused by a
loosening of the intermolecular forces in casein particles caused by solubilization of
colloidal calcium phosphate. We also suggest that in combination gels made from
unheated milk a low value for the fracture stress and a high tan δ during gelation
indicated an increased susceptibility of the network to excessive large scale
rearrangements. In contrast, combination gels made from heated milk formed firmer
gels crosslinked by denatured whey proteins and underwent fewer large scale
rearrangements.
Effects of intravenous infusion of amino acids and glucose on the yield and concentration of milk protein in dairy cows
Authors: KIM CHANG-HYUN , KIM TAE-GYU , CHOUNG JAI-JUN , CHAMBERLAIN DAVID G.
Published: July 2002

To test the hypothesis that the availability of glucose or its precursors can
influence the response of milk protein concentration to the intravenous infusion of
amino acids, five cows were used in a 5 × 5 Latin square design with period lengths
of 7 d. The five treatments were the basal diet of grass silage ad lib. plus 5 kg/d of a
cereal-based supplement containing feather meal (Basal); Basal plus 4 g/d histidine,
8 g/d methionine and 26 g/d lysine (4H); Basal plus 8 g/d histidine, 8 g/d methionine
and 26 g/d lysine (8H); and these two amino acid mixtures together with 600 g/d of
glucose (4HG and 8HG respectively). Earlier experiments with this basal diet had
shown that histidine was first-limiting for secretion of milk protein, followed by
methionine and lysine. The yield of milk protein was increased progressively with the
amount of histidine infused. The efficiency of transfer of histidine into milk protein
was 0·42 for the 4H and 4HG and 0·35 for the 8H and 8HG treatments, and the
concentration of milk protein was increased over Basal by all infusion treatments.
However, milk protein concentrations were higher, and lactose concentrations in the
milk were lower, in the absence of added glucose. Concentrations of insulin in blood
plasma were not affected by treatment. It is concluded that, with the treatments
without added glucose, a shortage of glucose prevented an increase in lactose
secretion, and hence limited the increase in milk yield, leading to an increased
concentration of protein in the milk.
Determination of the animal origin of raw food by species-specific PCR
Authors: HERMAN LIEVE
Published: July 2002

Specific PCR, amplifying a fragment of the mitochondrially encoded cytochromeb gene, are developed for discrimination of chicken, turkey, pig, cow and sheep. These PCR tests could be applied for detection and discrimination of animal food ingredients. For origin identification of milk, the bovine PCR is applied on DNA extracted with the DNeasy™ Tissue kit. A PCR of 30 cycles reached a sensitivity of 720 somatic cells in the PCR reaction corresponding to 2·9 × 104 cells per ml milk. A PCR of 40 cycles could detect 0·72 to 0·144 somatic cells in the PCR reaction corresponding to 29 to 2·9 cells per ml milk.
Effects of stage of lactation, milk protein genotype and body
condition at calving on protein composition and renneting properties
of bovine milk
Authors: OSTERSEN STEEN , FOLDAGER JOHN , HERMANSEN JOHN E.
Published: July 2002

The lactational variation in milk protein composition and renneting

properties and their relationship to the cow's body condition at calving
were
investigated in 39 Danish Holstein first lactation cows fed on a well balanced

standard diet. All milk characteristics measured were
significantly affected by stage
of lactation (P<0·01). Casein as a proportion of
total milk nitrogen reached a
maximum in mid lactation. The proportion of αs- and
κ-casein in total casein
decreased and the proportion of β-casein increased
systematically during lactation
while the proportion of γ-casein was lowest in mid
lactation. The α-lactalbumin
content of milk and its proportion of total whey proteins decreased
during lactation.
Renneting time was highest and curd firmness lowest in mid lactation. These
results
appeared to reflect a low degree of proteolysis in late-lactation milks
compared with
several other investigations, probably because of the good nutritional
state of the
cows. The body condition at calving affected proteolysis and the renneting
properties
of milk. A good body condition increased the content of whey protein in
total milk
nitrogen and of γ-casein in total caseins
(P<0·05); in addition, curd firmness was
improved (P<0·01) and aggregation time was reduced
(P<0·05). We suggest that
these effects were related to the fat metabolism and energy status
of the cows during
lactation. The interrelationships between the milk characteristics were
evaluated by
factor analysis to support the interpretation.
Free active peptidases are detected in Emmental
juice extracted before ripening in the warm room
Authors: GAGNAIRE VALERIE , LORTAL SYLVIE , LEONIL JOELLE
Published: July 2002

In Swiss-type cheese such as Emmental, proteolysis
is one of the major
phenomena occurring during ripening. Among the proteolytic
agents involved in
cheese ripening, the free enzymes originally present in
milk and those arising from
bacterial autolysis can act directly on the casein network.
In order to understand the
contribution of the bacterial enzymes and especially those
arising from the
thermophilic starters, the juice of an Emmental cheese
entering the warm room was
extracted by pressure, then sterilized by filtration and
incubated at 24°C for 20 d
under anaerobiosis. At different times, the peptides and
free amino acids were
determined in the sterile cheese juice. In parallel, in
order to gather information
about the nature of the enzymes present, the sterile
juice was also incubated with
β-naphthylamide derivatives as substrates. We have
demonstrated a continuous
increase in free NH2 groups and in free amino
acids throughout the 20 d incubation
time. The main peptidase activity was due to
aminopeptidase(s) and X-prolyldipeptidyl aminopeptidase(s)
whose activities were recovered after non-denaturing
polyacrylamide gel electrophoresis. Most of the enzymes
found in the juice would
have their origin in thermophilic starters. As they are
generally intracellularly
located, their release could be explained by the autolysis
of these starters. Finally,
the main free amino acids released in the juice (Pro,
Glu, Ala, Val, Leu and Lys)
corresponded to those previously found in Emmental cheese,
suggesting that the
enzymes detected in this study participate significantly
in peptide degradation during ripening.
Expression polymorphism of κ-casein gene in Holstein cows
Authors: ROBITAILLE GILLES , PETITCLERC DENIS
Published: July 2002

Several studies have reported associations between κ-casein (κ-CN) genetic
variants A and B and milk composition and properties (for review, see Ng-Kwai-
Hang, 1998). For instance, genetic variant κ-CN B was associated with higher
protein, casein and κ-CN contents. The objective of the present study was to
demonstrate a differential expression of κ-CN genetic variants A and B at the mRNA
level in mammary epithelial cells during lactation.
Linear stability analysis of channel inception: downstream-driven theory
Authors: IZUMI NORIHIRO , PARKER GARY
Published: July 2002

A linear stability analysis of incipient channellization on hillslopes is performed using
the shallow-water equations and a description of the erosion of a cohesive bed. The
base state consists of a laterally uniform Froude-subcritical sheet flow down a smooth,
downward-concave hillslope profile. The downstream boundary condition consists of
the imposition of a Froude number of unity. The process of channellization is thus
driven from the downstream end. The flow and bed profiles describe a base state
that migrates at constant, slow speed in the upstream direction due to bed erosion.
Transverse perturbations corresponding to a succession of parallel incipient channels
are introduced. It is found that these perturbations grow in time, so describing incipient
channellization, only when the characteristic spacing between incipient channels is on
the order of 6–100 times the Froude-critical depth divided by the resistance coefficient.
The characteristic wavelength associated with maximum perturbation growth rate
is found to scale as 10 times the Froude-critical depth divided by the resistance
coefficient. Evaluating the friction coefficient as on the order of 0.01, an estimate
of incipient channel spacing on the order of 1000 times the Froude-critical depth is
obtained. The analysis reveals that downstream-driven channellization becomes more
difficult as (a) the critical shear stress required to erode the bed becomes so large that
it approaches the Froude-critical shear stress reached at the downstream boundary
and (b) the Froude number of the subcritical equilibrium flow attained far upstream
approaches unity. Alternative mechanisms must be invoked to explain channellization
on slopes high enough to maintain Froude-supercritical sheet flow.
Reynolds-number scaling of the flat-plate turbulent boundary layer
Authors: DE GRAAFF DAVID B. , EATON JOHN K.
Published: July 2002

Despite extensive study, there remain significant questions about the Reynolds-number
scaling of the zero-pressure-gradient flat-plate turbulent boundary layer. While the
mean flow is generally accepted to follow the law of the wall, there is little consensus
about the scaling of the Reynolds normal stresses, except that there are Reynolds-number effects even very close to the wall. Using a low-speed, high-Reynolds-number
facility and a high-resolution laser-Doppler anemometer, we have measured Reynolds
stresses for a flat-plate turbulent boundary layer from Reθ = 1430 to 31 000. Profiles
of u′2, v′2, and
u′v′ show reasonably
good collapse with Reynolds number: u′2 in a new
scaling, and v′2 and u′v′
in classic inner scaling. The log law provides a reasonably
accurate universal profile for the mean velocity in the inner region.
A theoretical model of a turbulent fountain
Authors: BLOOMFIELD LYNN J. , KERR ROSS C.
Published: July 2002

A theoretical model of axisymmetric turbulent fountains in both homogeneous and
stratified fluids is developed. The model quantifies the entrainment of ambient fluid
into the initial fountain upflow, and the entrainment of fluid from both the upflow
and environment into the subsequently formed downflow. Four different variations
of the model are considered, comprising the two most reasonable formulations of
the body forces acting on the ‘double’ structure and two formulations of the rate of
entrainment between the flows. The four model variations are tested by comparing
the predictions from each of them with experimental measurements of fountains in
homogeneous and stratified fluids.
Viscous beads on vertical fibre
Authors: KLIAKHANDLER I. L. , DAVIS S. H. , BANKOFF S. G.
Published: July 2002

The dynamics of a thick layer of viscous liquid flowing down a thin vertical fibre is
investigated. Three qualitatively different regimes of the interfacial patterns in the form
of beads were observed experimentally. Two typical regimes at relatively small flow
rate are described reasonably well by the creeping-flow model equation proposed here.
Nonlinear effects in two-layer large-amplitude geostrophic dynamics.
Part 1. The strong-beta case
Authors: KARSTEN RICHARD H. , SWATERS GORDON E.
Published: July 2002

Baroclinic large-amplitude geostrophic (LAG) models, which assume a leading-order
geostrophic balance but allow for large-amplitude isopycnal deflections, provide a
suitable framework to model the large-amplitude motions exhibited in frontal regions.
The qualitative dynamical characterization of LAG models depends critically on the
underlying length scale. If the length scale is sufficiently large, the effect of differential
rotation, i.e. the β-effect, enters the dynamics at leading order. For smaller length
scales, the β-effect, while non-negligible, does not enter the dynamics at leading
order. These two dynamical limits are referred to as strong-β and weak-β models,
respectively.

A comprehensive description of the nonlinear dynamics associated with the strong-
β models is given. In addition to establishing two new nonlinear stability theorems,
we extend previous linear stability analyses to account for the finite-amplitude development
of perturbed fronts. We determine whether the linear solutions are subject
to nonlinear secondary instabilities and, in particular, a new long-wave–short-wave
(LWSW) resonance, which is a possible source of rapid unstable growth at long length
scales, is identified. The theoretical analyses are tested against numerical simulations.
The simulations confirm the importance of the LWSW resonance in the development
of the flow. Simulations show that instabilities associated with vanishing potential-
vorticity gradients can develop into stable meanders, eddies or breaking waves. By
examining models with different layer depths, we reveal how the dynamics associated
with strong-β models qualitatively changes as the strength of the dynamic coupling
between the barotropic and baroclinic motions varies.
A numerical study of the particle size distribution
of an aerosol undergoing turbulent coagulation
Authors: READE WALTER C. , COLLINS LANCE R.
Published: July 2002

Coagulation and growth of aerosol particles subject to isotropic turbulence has been
explored using direct numerical simulations. The computations follow the trajectories
of 262 144 initial particles as they are convected by the turbulent flow field. Collision
between two parent particles leads to the formation of a new daughter particle with
the mass and momentum (but not necessarily the energy) of the parent particles. The
initially monodisperse population of particles will develop a size distribution over
time that is controlled by the collision dynamics. In an earlier study, Sundaram &
Collins (1997) showed that collision rates in isotropic turbulence are controlled by
two statistics: (i) the radial distribution of the particles and (ii) the relative velocity
probability density function. Their study considered particles that rebound elastically;
however, we find that the formula that they derived is equally valid in a coagulating
system. However, coagulation alters the numerical values of these statistics from the
values they attain for the elastic rebound case. This difference is substantial and must
be taken into consideration to properly predict the evolution of the size distribution
of a population of particles. The DNS results also show surprising trends in the
relative breadth of the particle size distribution. First, in all cases, the standard
deviation of the particle size distribution of particles with finite Stokes numbers is
much larger than the standard deviation for either the zero-Stokes-number or infinite-Stokes-number limits. Secondly, for particles with small initial Stokes numbers, the
standard deviation of the final particle size distribution decreases with increasing
initial particle size; however, the opposite trend is observed for particles with slightly
larger initial Stokes numbers. An explanation for these phenomena can be found by
carefully examining the functional dependence of the radial distribution function on
the particle size and Stokes number.
The spreading of surfactant-laden liquids with surfactant transfer through the contact line
Authors: RAMÉ ENRIQUE
Published: July 2002

We examine the spreading of a liquid on a solid surface when the liquid surface has
a spread monolayer of insoluble surfactant, and the surfactant transfers through the
contact line between the liquid surface and the solid. We show that, as in surfactant-free
systems, a singularity appears at the moving contact line. However, unlike
surfactant-free systems, the singularity cannot be removed by the same assumptions
as long as surfactant transfer takes place. In an attempt to avoid modelling difficulties
posed by the question of how the singularity might be removed, we identify parameters
which describe the dynamics of the macroscopic spreading process. These parameters,
which depend on the details of the fluid motion next to the contact line as in the
pure-fluid case, also depend on the state of the spread surfactant in the macroscopic
region, in sharp contrast to the pure-fluid case where actions at the macroscopic
scale did not affect material spreading parameters. A model of the viscous-controlled
region near the contact line which accounts for surfactant transfer shows that, at
steady state, some ranges of dynamic contact angles and of capillary number are
forbidden. For a given surfactant–liquid pair, these disallowed ranges depend upon
the actual contact angle and on the transfer flux of surfactant.

We also examine a possible inner model which accounts for the transfer via surface
diffusivity and regularizes the stress via a slip model. We show that the asymptotic
behaviour of this model at distances from the contact line large compared to the
inner length scale matches to the viscous-controlled region. An example of how the
information propagates is given.
Shear-induced particle diffusivities from numerical simulations
Authors: MARCHIORO MARCO , ACRIVOS ANDREAS
Published: July 2002

Using Stokesian dynamics simulations, we examine the flow of a monodisperse,
neutrally buoyant, homogeneous suspension of non-Brownian solid spheres in simple
shear, starting from a large number of independent hard-sphere distributions and
ensemble averaging the results. We construct a novel method for computing the
gradient diffusivity via simulations on a homogeneous suspension and, although our
results are only approximate due to the small number of particles used in the
simulations, we present here the first values of this important parameter, both along
and normal to the plane of shear, to be obtained directly either experimentally or
numerically. We show furthermore that, although the system of equations describing
the particle motions is deterministic, the particle displacements in the two directions
normal to the bulk flow have Gaussian distributions with zero mean and a variance
which eventually grows linearly in time thereby establishing that the system of particles
is diffusive. For particle concentrations up to 45%, we compute the corresponding
tracer diffusivities both from the slope of the mean-square particle displacement and
by integrating the corresponding velocity autocorrelations and find good agreement
between the two sets of results.
Break-up of a falling drop containing dispersed particles
Authors: NITSCHE J. M. , BATCHELOR G. K.
Published: July 2002

The general purpose of this paper is to investigate some consequences

of the randomness of the velocities of interacting rigid particles falling
under

gravity through viscous

fluid at small Reynolds number. Random velocities often imply diffusive
transport

of the particles, but particle diffusion of the conventional kind exists
only

when the

length characteristic of the diffusion process is small compared with the
distance

over which the particle concentration is effectively uniform. When this
condition

is not satisfied, some alternative analytical description of the dispersion

process is

needed. Here we suppose that a dilute dispersion of sedimenting particles
is bounded

externally by pure fluid and enquire about the rate at which particles
make outward

random crossings of the (imaginary) boundary. If the particles are initially

distributed

with uniform concentration within a spherical boundary, we gain the convenience

of approximately steady conditions with a velocity distribution like that
in

a falling

spherical drop of pure liquid. However, randomness of the particle velocities
causes

some particles to make an outward crossing of the spherical boundary and
to be

carried round the boundary and thence downstream in a vertical ‘tail’.

This is the nature of break-up of a falling cloud of particles.

A numerical simulation of the motion of a number of interacting particles

(maximum 320) assumed to act as Stokeslets confirms the validity of the
above picture

of the way in which particles leak away from a spherical cluster of particles.
A

dimensionally correct empirical relation for the rate at which particles
are

lost from

the cluster involves a constant which is indeed found to depend only weakly
on the

various parameters occurring in the numerical simulation. According to
this relation

the rate at which particles are lost from the blob is proportional to the

fall speed of

an isolated particle and to the area of the blob boundary. Some photographs
of a

leaking tail of particles in figure 5 also provide support for the

qualitative picture.
Three-dimensionally perturbed vortex tubes in a rotating flow
Authors: CARNEVALE G. F. , BRISCOLIN M. , KLOOSTERZIEL R. C. , VALLIS G. K.
Published: July 2002

Numerical experiments are used to study the evolution of perturbed

vortex tubes in a

rotating environment in order to better understand the process of

two-dimensionalization of unsteady rotating flows. We specifically

consider non-axisymmetric perturbations to columnar vortices aligned

along the axis of rotation. The basic unperturbed

vortex is chosen to have a Gaussian cross-sectional vorticity distribution.

The experiments cover a parameter space in which both the strength of the

initial perturbation

and the Rossby number are varied. The Rossby number is defined here as
the ratio of

the maximum amplitude of vorticity in the Gaussian vorticity profile to
twice

the ambient rotation rate. For small perturbations and small Rossby numbers,

both cyclones

and anticyclones behave similarly, relaxing rapidly back toward two-dimensional

columnar vortices. For large perturbations and small Rossby numbers, a
rapid

instability occurs for both cyclones and anticyclones in which antiparallel

vorticity is

created. The tubes break up and then re-form again into columnar vortices
parallel to

the rotation axis (i.e. into a quasi-two-dimensional flow) through

nonlinear processes.

For Rossby numbers greater than 1, even small perturbations result in the
complete

breakdown of the anticyclonic vortex through centrifugal instability, while
cyclones

remain stable. For a range of Rossby numbers greater than 1, after the
breakdown

of the anticyclone, a new weaker anticyclone forms, with a small-scale
background

vorticity of spectral shape given approximately by the −5/3 energy

spectral law.
Three-dimensional eddy structure in a cylindrical container
Authors: SHANKAR P. N.
Published: July 2002

We consider Stokes flow in a cylindrical container of circular

section induced by the

uniform translatory motion of one of the endwalls. This flow field is of

interest because

it is possible to get reliable analytical descriptions of important three-dimensional

structures such as the primary and corner eddies. It is shown, using a

result of Tran-Cong & Blake, that separable solutions exist which can

be combined to yield vector

eigenfunctions that satisfy the sidewall boundary conditions provided the
eigenvalues

satisfy the transcendental equation

formula here