bluuebunny/crossref_metadata_2025 huggingface dataset:
INCREASING WATER PRODUCTIVITY AND WEED SUPPRESSION OF WET SEEDED RICE: EFFECT OF WATER MANAGEMENT AND RICE GENOTYPES
Authors: TUONG T. P. , PABLICO P. P. , YAMAUCHI M. , CONFESOR R. , MOODY K.
Published: July 2002

Weeds are major constraints to wider adoption of wet seeded rice. Two split-plot experiments on water management during crop establishment of wet seeded rice were conducted in the dry and wet seasons of 1994 to quantify crop stand establishment and weed suppression by herbicides and rice genotypes. The latter consisted of five previously identified hypoxic-tolerant lines and three standard cultivars, sown at approximately 300 seeds m−2. The tested hypoxic-tolerant genotypes had superior seedling growth, but not higher crop stand establishment than the standard ones. Genotypes that had superior crop stand establishment or faster seedling growth did not necessarily give better weed suppression. Genotypes with high tillering ability were more competitive against weeds. Echinochloa glabrescens dominated the weed flora, especially in farmers' practice and anaerobic seeding (seeding into soft mud), followed by flooding at 7 d after seeding (DAS). The relative proportion of Monochoria vaginalis increased in anaerobic seeding with flooding 3 DAS and seeding into standing water. Pretilachlor + fenclorim effectively controlled weeds in farmers' practice and anaerobic seedings, and 2,4-D in water seeding. Without herbicide, water seeding and anaerobic seeding flooded 3 DAS reduced dry weed weight by 73–88% compared with farmers' practice. Anaerobic seeding with flooding 7 DAS controlled weeds effectively when the weed pressure was low (dry season, about 136 g m−2 of weed biomass in plots without herbicide) but not when weed pressure was high (wet season, 513 g m−2). Water seeding could not sustain high rice yields due to low crop stand population caused by flotation of seedlings. Anaerobic seeding with flooding 3 DAS allowed genotypes to sustain high yield and increased water productivity (rice production per unit volume of water used in the field) without having to use herbicide or with only half of the recommended herbicide rate. The correct water management during the crop establishment stage may effectively lower the economic and possible runoff costs of herbicides without reduction in yield or water productivity.
PARTICIPATORY EVALUATION BY FARMERS OF ON-FARM SEED PRIMING IN WHEAT IN INDIA, NEPAL AND PAKISTAN
Authors: Harris D. , Raghuwanshi B. S. , Gangwar J. S. , Singh S. C. , Joshi K. D. , Rashid A. , Hollington P. A.
Published: July 2002

The mean time for 50% germination at 20 °C of 12 Indian wheat (Triticum aestivum) cultivars was nearly halved, from 51 h to 27 h, by soaking seed in water for 8 h prior to sowing. A delay of 24 h without further soaking, intended to simulate postponement of sowing, reduced the time saved by priming to 16%. Priming had no effect on final germination percentage. These results were used in the design of 275 on-farm, farmer-managed, participatory trials of seed priming in wheat during the 1997–98 and 1998–99 rabi (post-monsoon) seasons. In forty-one trials in tribal areas of Bihar and West Bengal states of India, seed priming gave a 13% grain yield advantage for farmers growing wheat in marginal areas with low levels of agricultural inputs. Mean benefits from seed priming of wheat in nine trials in Chitwan, Nepal were 17%. In high potential areas of Gujarat, India, 205 trials had higher rates of input use. Yield benefit from priming in these trials averaged only 5% but constituted an extra 200 kg ha−1 grain at little or no cost. In 20 trials on marginal land, with slightly saline irrigation water in Ahmadwala, Pakistan, an average yield increase of 36% was obtained using seed primed with a 0.2% gypsum solution. Collaborating farmers reported that priming wheat seed overnight resulted in faster, more complete emergence, more vigorous early growth, better tillering, earlier flowering, larger ears, earlier maturity and higher yields. In addition, many farmers also reported that foliage in primed plots was a darker shade of green than that in non-primed plots, suggesting that primed plants may have been using nitrogen more efficiently. Seed priming was popular with farmers, most of whom reported that they would prime wheat seed the following year. A survey in Gujarat in 1998–99 of 63 farmers who had tested priming in 1997–98 showed that, while 65% had primed some of their own seed, none had primed more than 50 kg, suggesting that there were practical difficulties in priming larger volumes of seed.
Uncv (uncovered): a new mutation causing hairloss on
mouse chromosome 11
Authors: LI SHAN-RU , WANG DONG-PING , YU XIU-LING , GE BAO-SHENG , WANG CUI-E , LU YI-FAN , LI JI-QING , WU NA , LI RUN-FANG , ZHU SHI-EN , ZHANG ZHONG-CHENG , CHEN YONG-FU
Published: July 2002

A pair of mutant mice with a first sparse coat appeared spontaneously in the production stock of
BALB/c mice with a normal coat. After being sib-mated, they produced three phenotypes in their
progeny: mice with normal hair, mice with a first sparse coat and then a fuzzy coat, and
uncovered mice. Genetic studies revealed the mutants had inherited an autosomal monogene that
was semi-dominant. By using 11 biochemical loci – Idh, Car2,
Mup1, Pgm1, Hbb, Es1, Es10, Gdc,
Ce2, Mod1 and Es3 – as genetic markers, two-point linkage tests were made. The results showed
the gene was assigned to chromosome 11. The result of a three-point test with Es3 and D11Mit8
(microsatellite DNA) as markers showed that the mutation was linked to Es3 with the
recombination fraction 7·89±2·19%, and linked to D11Mit8 with the recombination fraction
26·30±3·57%. The recombination fraction between Es3 and D11Mit8 was 32·90±3·81%. It is
suggested that the mutation is a new genetic locus that affected the skin and hair structure of the
mouse. The mutation was named uncovered, with the symbol Uncv. Further studies showed the
mutation affected not only the histology of skin and hair but also the growth and reproductive
performance of the mice. The molecular characterization of the Uncv locus needs to be further
studied.
Analysis of mutation accumulation experiments: response to
Deng, Li and Li
Authors: KEIGHTLEY PETER D.
Published: July 2002

A recent paper in this journal by Deng, Li and Li has investigated methods to estimate rates and
effects of polygenic mutations using data from mutation accumulation experiments. Here, I
evaluate a number of critical points in this paper concerning a maximum likelihood (ML)
procedure to analyse mutation accumulation data. I show that Deng, Li and Li's criticisms are
based on misunderstandings, or numerical problems they encountered that could have been readily
overcome. In Monte Carlo simulations, I show that ML can give a considerable increase in
precision over the method of moments that is traditionally used to analyse mutation accumulation
data. Furthermore, ML allows the comparison of the fit of different models for the distribution of
mutation effects.
P. M. HOLT, The Sudan of the Three Niles: The Funj Chronicle, 910–1288/1504–1871, Islamic History and Civilization: Studies and Texts (Leiden: E. J. Brill, 1999). Pp. 228. $71.00 cloth.
Authors: Sharkey Heather J.
Published: July 2002

P. M. Holt's The Sudan of the Three Niles is an annotated translation of the Funj Chronicle, a history of the Funj sultanate (1504–1821) based at Sennar, along the Blue Nile, and of the Turco-Egyptian regime that succeeded it at Khartoum. Along with the Tabaqat of Wad Dayf Allah (a biographical dictionary of Sudanese Muslim holy men compiled in the late 18th century), the Funj Chronicle is the most important Arabic source on the northern riverain Sudan in the Funj era, a period in which Islam was spreading widely and the region was developing its pronounced Arab–Islamic identity.
“Performing Inter-Nationalism” in Stuttgart in 1907: French and German Socialist Nationalism and the Political Culture of an International Socialist Congress
Authors: Callahan Kevin
Published: July 2002

The emphasis on ritual, political symbolism and public display at international socialist congresses highlights important cultural dimensions of the Second International that historians have, until now, left unexplored. From 1904 until the International Socialist Congress of Stuttgart in 1907, French and German socialists articulated – in both symbolic and discursive forms – a socialist nationalism within the framework of internationalism. The Stuttgart congress represented a public spectacle that served a cultural function for international socialism. The international performance at Stuttgart was, however, undermined by the inability of the SFIO and the SPD to reconcile their conflicting conceptions of “inter-nationalism”.
MORE SOUTH AFRICAN SHENANIGANS The Origins of the South African War,

1899–1902. By IAIN R. SMITH. London

and New York: Longman, 1995. Pp. xix + 455. £15.99

(ISBN 0-582-27777-9).
Authors: NASSON BILL
Published: July 2002

In some ways, The Origins of the South African War

1899–1902 is an awfully fat book for what has perhaps

become an awfully thin and fatiguing subject. Do we really need yet

another stab at J. A. Hobson on the Jameson Raid and the notion of the

capitalist conspiracy war? Is there much to be gained from further

deliberation over the 1896 Selborne Memorandum dealing with the crisis

in South Africa? Despite Dr Smith's suggestion (p. x) that recent

historiography of the South African War has been preoccupied more with

the experience of that conflict than with its origins, the fact

remains that modern English-language scholarship on the causes of the

war, starting well over three decades ago with Robinson and

Gallagher's Africa and the Victorians, continues to

outweigh heavily writing on the actual conduct of hostilities between

Britain and the Boer republics. We continue to know much more about

the pre-war shenanigans between Milner and the Uitlanders than about

the relationship between technology and strategy during

1899–1902 or the demographic consequences of an exhausting war.

So, the question must be: does Iain Smith breathe new life into the

enormously complex, broadly familiar, sometimes tedious, historical

arguments over the origins of the South African War?
The Congo. By RANDALL FEGLEY. (World

Bibliographical Series, Vol. 162.) Oxford, Santa Barbara and Denver:

Clio Press, 1993. Pp. 1 + 168. £30 (ISBN 1-85109-199-8).
Authors: BERNAULT FLORENCE
Published: July 2002

Randall Fegley's bibliographical compilation is clearly

not among the best of the World Bibliographical Series. The

objective of the collection is to present a solid guide of the country

to the non-specialist, and compared to other volumes in the series,

Fegley's work lacks polish and perspective. The volume is marked

by spelling errors. Accents in French names and titles are most often

ignored. Important authors' names are misspelled: Gilles Sautter

becomes ‘Giles’ in the text and ‘Sautte’ in

the index; Jean-Claude Willame becomes ‘Willaure’.

Ironically, the listing of the latter's book, Patrimonialism

and Change in the Congo, a political science essay on Zaïre,

illustrates the mistake Fegley denounces in his preface (p. xiii) :

most English-speaking readers confuse Zaïre and Congo. The

well-known collection of essays edited by P. Gifford and W. R. Louis

is wrongly entitled by Fegley as Transfers of Power in

Africa, and presented as a single volume (p. 68). Some titles are

also poorly categorized, like René Gauze's The

Politics of Congo-Brazzaville. Gauze's 150-page text is

devoted to Congolese politics during the colonial period, with a

50-page supplement on the decade 1962 to 1972 written by Virginia

Thompson and Richard Adloff. It is nevertheless classified only under

‘Post-colonial politics’ (p. 71). Jan Vansina's

Paths in the Rainforest, best classified in pre-colonial

history, is listed just once under ‘Politics,

General’.
REVIEW A review of some studies into tuber initiation in potato
(Solanum tuberosum) crops
Authors: O'BRIEN P. J. , ALLEN E. J. , FIRMAN D. M.
Published: July 2002

Despite the importance of potato tubers as a source of
food and a means of propagation, the initiation,
growth and development of tubers and the factors
affecting these processes are not well understood.
There are many reported studies of the effects of
various factors on the initiation of tubers but, for a
number of reasons, few have sought to understand the
initiation of tubers under field conditions. Most
reports are concerned with experiments carried out in
growth-rooms, which often used very short stem
sections as planting material and in which environmental conditions,
especially light intensity, differed
greatly from those normally prevailing during the
period of initiation in the field. In almost all field
experiments, the timing of initiation was not defined
or properly assessed; number of tubers was recorded
infrequently and maximum number of tubers was
rarely, if ever, established. Despite these deficiencies,
the initiation of tubers is still widely regarded as a
key developmental stage in the crop's life, having
profound implications for subsequent growth and
development (Ewing 1990; Ewing & Struik 1992).
This view was first expressed 30 years ago (Ivins &
Bremner 1965; Bremner & Radley 1966) and its
general acceptance has greatly influenced studies of
the growth and development of the crop. During the
intervening years, the study of tuber initiation has
been an important aspect of research programmes at
the University College of Wales (UCW) Field Station,
Tenby, Pembrokeshire (1972–84) and Cambridge
University Farm (CUF), Cambridge (1982–95), which
have now produced sufficient data for a re-evaluation
of the significance of tuber initiation in field-grown potato crops.
Effects of weight loss in ewes in early pregnancy on
muscles and meat quality of lambs
Authors: KRAUSGRILL D. I. , TULLOH N. M. , SHORTHOSE W. R. , SHARPE K.
Published: July 2002

Three successive experiments, of similar design, were carried out during 1986–88 at Mount Derrimut,
Australia. Mature Merino ewes were mated to Poll Dorset rams and then allocated to either a control
group (C) or a treatment group (R). Ewes from each treatment were slaughtered 60, 70, 100 or 140
days post-conception and the development of their foetuses was compared in terms of body size and
muscle characteristics. In Expts 1 and 2, some ewes were allowed to lamb and the progeny in each
group were slaughtered after reaching a body weight of 35 kg, for comparison of growth rates, muscle
characteristics and meat quality.

In each experiment, treatment extended from mating to day 70 of pregnancy and, during this
period, both groups were housed. Ewes in group C were kept as one group and fed ad libitum and
ewes in group R were individually penned and fed a restricted ration of the same diet as that given
to group C in order to achieve a steady loss of body weight. In Expt 1, this loss was 8 kg but, in Expts
2 and 3, feed intake was controlled according to condition score and, during this period, group R ewes
lost 25–35% of their body weight at mating. After day 70, all ewes were kept grazing and were offered
supplementary feed at rates sufficient for a steady increase in ewe body weights.

Foetuses in group R were lower in body weight (P<0·05), crown-rump length (P<0·05) and girth
(P<0·01). However, birth weights and mean ages of the 35 kg lambs at slaughter did not differ
significantly between treatments.

There were no significant differences between treatments for the semitendinosus (ST) and
semimembranosus (SM) muscles in total muscle weight, DNA content, protein content, nor in the
ratios of muscle weight[ratio ]DNA and protein[ratio ]DNA. However, there were significant differences between
experiments, which indicated that cell size in the ST and SM muscles was lower in Expt 2 than in
Expt 1.

In day 70 foetuses, the cross-sectional area of α fibres was greater (P<0·05) in group R than in
group C but by day 140 the difference was no longer significant. At day 70, there was also a positive
correlation (r=0·65, P<0·01) between the cross-sectional area of β fibres and the number of α fibres
surrounding each of them. There were no significant differences between treatments at any age in the
percentages of βR, αR and αW fibres.

Meat from group R lambs was more tender than that from group C lambs as indicated by
significantly lower means in the SM muscle for adhesion (P<0·01) and Warner–Bratzler Peak Force
(WB PF) measurements (P<0·05).

Although some effects of nutritional restriction were found, severe feed shortage in early pregnancy
in sheep is unlikely to have significant effects on the production of prime lamb meat provided that
adequate nutrition is available during late pregnancy and post-natal growth.
The effect of winter cover crops on yield of the
following spring crops and nitrogen balance in a
calcareous loam
Authors: GARWOOD T. W. D. , DAVIES D. B. , HARTLEY A. R.
Published: July 2002

The recovery of nitrogen ‘retained’ through cover crop
uptake, delayed ploughing and
immobilization by straw was assessed in a spring cropping rotation on a
chalk loam in Eastern
England (1989–96). The effect of annual cover cropping on yield of
the subsequent spring crops and
on the soil N balance was also investigated. The recovery of retained N
was in part dependent upon
cover crop management. Late August-sown cover crops which were incorporated
in February/March
tended to reduce spring crop yields and crop N offtake. Adverse effects
on soil N supply, seedbed
conditions and soil water reserves were not in evidence and so an allelopathic
effect from the
decomposition of the rye cover crop, previously reported by others, may
be responsible for the
reduction in yield of spring crops. When the cover crops were drilled later
and their early destruction
was followed by a short fallow period, spring crop yields and N offtake
were increased. The soil N
balance indicated that over the course of the experiment there was a positive
N input to the system
due to continuous cover cropping. This input may be held as immobilized
organic N, in which case
it could be made available to subsequent crops over a number of years or
lost via other routes. Nitrate
concentrations in drainage water increased with the number of years under
cover cropping.
Infiltration of slurry liquid and volatilization of
ammonia from surface applied pig slurry as affected by
soil water content
Authors: SOMMER S. G. , JACOBSEN O. H.
Published: July 2002

Ammonia (NH3) volatilization may decrease the fertilizer efficiency of surface-applied slurry and may
cause the unwanted deposition of nitrogen (N) in oligotrophic ecosystems. We studied the effect of
soil water content on the infiltration of slurry liquid and how infiltration affected NH3 volatilization.
NH3 volatilization was measured with dynamic chambers through which air was drawn continuously.
Slurry spiked with bromide (Br−) to trace slurry infiltration was applied to a loamy sand in steel
cylinders (diameter 6·7 cm and height 12 cm) adjusted to water contents of 0·01, 0·08, 0·12 and
0·19 g H2O per g soil (g g−1). At different time intervals after slurry application the soil columns were
cut into slices and Br−, ammonium (NH4+) and nitrate
(NO3−) concentrations were determined. At
soil water contents >0·12 g g−1 nitrate content increased
significantly from 24 to 72 h, and at 96 h NO3− content was
equivalent to 75–130% of the NH4+ present at 0·5 h after slurry application.
Nitrification may have contributed to a low NH3 volatilization from 24 to 96 h by reducing NH4+
concentration and contributing to acidity, and most of the NH3 volatilization occurred, therefore,
during the first 24 h after application. Low soil water content enhanced the infiltration of slurry liquid
and hence the mass transport of NH4+ into the soil. Transport of
NH4+ by diffusion, on the other
hand, was highest at the highest water content. Transport of NH4+
from the slurry at the soil surface
down into the soil at 0·01 g g−1
reduced NH3 volatilization to c. 70% of the volatilization from slurry
applied to soils at higher water contents. Diffusion of NH4+
into the soil did not significantly decrease
NH3 volatilization.
SIBLING MORTALITY CORRELATION IN KENYA
Authors: IKAMARI LAWRENCE
Published: July 2002

This paper examines whether infant and child mortality risks among successive siblings are closely correlated, and if so, whether the survival status of the preceding child is an important factor affecting infant and child mortality in Kenya. The data were drawn from the 1988/89 Kenya Demographic and Health Survey. Logistic regression was used as the major method of data analysis. The results show that both infant and child mortality rates are significantly higher among subsequent children whose preceding siblings had died in infancy than for those whose preceding sibling had survived through infancy. The effect of the survival status of the preceding child on infant mortality was statistically strong, even after a large number of control variables were taken into account. However, its effect on child mortality appears to be spurious since it was rendered statistically insignificant when just a few control variables were introduced into the analysis. The results provide empirical evidence that infant and child mortality risks among successive siblings are closely correlated in Kenyan families, and that the effect of the survival status of the preceding child is important in determining infant mortality but not child mortality.
MARITAL STRUCTURE OF THE ITALIAN COMMUNITY OF BOSTON, MASSACHUSETTS, 1880–1920
Authors: DANUBIO MARIA ENRICA , PETTENER DAVIDE
Published: July 2002

The marital structure of Italians living in Boston, Massachusetts, in the period 1880–1920 was studied in order to explore the integration process in the urban context. The study analyses endogamy and inbreeding, using data on 15,579 marriages from the parish books of the three Italian parishes of Boston. Endogamic rates are very high and increased in time, ranging from 93·9% to 97·3%. This correlated with the growth of the Italian community and the decline of the biased sex ratio. One parish, Our Lady of Pompeii in the South End, displays lower endogamic rates because of the reduced and scattered population attending it. The rate of consanguineous (2·33%) and isonymous (6·38%) marriages, and the coefficients of inbreeding, alpha; (0·98×10−3) and Ft (0·0159), are similar to those of north Italian populations, and lower than those for south and insular Italy. The parish of Our Lady of Pompeii shows consistently higher values than the other two parishes. Marriages between first and second cousins are the main cause of the above values in each parish. Consanguineous marriages and inbreeding increased over time, from the 1890s, and this is in general agreement, although slightly delayed, with the Italian trend.
Effect of decreased milking frequency of cows in late lactation on

milk somatic cell count, polymorphonuclear leucocyte numbers,
composition and proteolytic activity
Authors: KELLY ALAN L. , REID SUSAN , JOYCE PATRICK , MEANEY WILLIAM J. , FOLEY JOHN
Published: July 2002

The effects of reducing the frequency of milking of cows in late
lactation
on milk somatic cell count (SCC), polymorphonuclear leucocyte (PMN) content,

chemical composition and proteolytic activity were investigated. Intermittent

milking is frequently practised by Irish farmers in late lactation, and
the objective
of this study was to determine whether this procedure could be linked to
altered
quality of milk. Seventeen Holstein Friesian cows in late lactation (>215
d in milk)
were assigned to two treatment groups, and were either milked twice a day
until
drying-off (control group) or milked intermittently as the yield fell (test
group). Milk
composition and enzymic characteristics were measured on two occasions.
At the
first sampling, day 7, test cows were on once daily milking and at the
second, day 15,
the test cows were being milked every second day. Milk yields were significantly

lower in test than control animals and decreased between days 7 and 15
in both
groups. Milk SCC and PMN levels were increased on reducing milking frequency
and,
at day 15, the increase was not linked to decreased milk yield. Milk lactose
levels were
significantly decreased and pH, α-lactalbumin levels, plasmin activity
and
plasminogen activity significantly increased by reducing milking frequency.
In
conclusion, reduced frequency of milking in late lactation leads to the
production of
milk that is abnormal in character and this may be linked to reduced quality
of dairy
products manufactured from such milk.
High-pressure treatment of milk: effects on casein micelle structure
and on enzymic coagulation
Authors: NEEDS ERIC C. , STENNING ROBERT A. , GILL ALISON L. , FERRAGUT VICTORIA , RICH GILLIAN T.
Published: July 2002

High isostatic pressures up to 600 MPa were applied to samples of skim
milk before addition of rennet and preparation of cheese curds. Electron microscopy
revealed the structure of rennet gels produced from pressure-treated milks. These
contained dense networks of fine strands, which were continuous over much bigger
distances than in gels produced from untreated milk, where the strands were coarser
with large interstitial spaces. Alterations in gel network structure gave rise to
differences in rheology with much higher values for the storage moduli in the
pressure-treated milk gels. The rate of gel formation and the water retention within
the gel matrix were also affected by the processing of the milk. Casein micelles were
disrupted by pressure and disruption appeared to be complete at treatments of
400 MPa and above. Whey proteins, particularly β-lactoglobulin, were progressively
denatured as increasing pressure was applied, and the denatured β-lactoglobulin was
incorporated into the rennet gels. Pressure-treated micelles were coagulated rapidly
by rennet, but the presence of denatured β-lactoglobulin interfered with the
secondary aggregation phase and reduced the overall rate of coagulation. Syneresis
from the curds was significantly reduced following treatment of the milk at 600 MPa,
probably owing to the effects of a finer gel network and increased inclusion of whey
protein. Levels of syneresis were more similar to control samples when the milk was
treated at 400 MPa or less.
A theory for turbulent pipe and channel flows
Authors: WOSNIK MARTIN , CASTILLO LUCIANO , GEORGE WILLIAM K.
Published: July 2002

A theory for fully developed turbulent pipe and channel flows is proposed which
extends the classical analysis to include the effects of finite Reynolds number. The
proper scaling for these flows at finite Reynolds number is developed from dimensional
and physical considerations using the Reynolds-averaged Navier–Stokes equations.
In the limit of infinite Reynolds number, these reduce to the familiar law of the wall
and velocity deficit law respectively.

The fact that both scaled profiles describe the entire flow for finite values of
Reynolds number but reduce to inner and outer profiles is used to determine their
functional forms in the ‘overlap’ region which both retain in the limit. This overlap
region corresponds to the constant, Reynolds shear stress region
(30 < y+ < 0.1R+
approximately, where R+ = u*R/v).
The profiles in this overlap region are logarithmic,
but in the variable y + a where a is an offset. Unlike the classical theory, the additive
parameters, Bi, Bo, and log coefficient,
1/κ, depend on R+. They are asymptotically
constant, however, and are linked by a constraint equation. The corresponding friction
law is also logarithmic and entirely determined by the velocity profile parameters, or
vice versa.

It is also argued that there exists a mesolayer near the bottom of the overlap
region approximately bounded by 30 < y+ < 300 where there is not the necessary
scale separation between the energy and dissipation ranges for inertially dominated
turbulence. As a consequence, the Reynolds stress and mean flow retain a Reynolds
number dependence, even though the terms explicitly containing the viscosity are
negligible in the single-point Reynolds-averaged equations. A simple turbulence model
shows that the offset parameter a accounts for the mesolayer, and because of it a
logarithmic behaviour in y applies only beyond y+ > 300, well outside where it has
commonly been sought.

The experimental data from the superpipe experiment and DNS of channel flow
are carefully examined and shown to be in excellent agreement with the new theory
over the entire range 1.8 × 102 < R+ < 5.3 × 105.
The Reynolds number dependence of all the parameters and the friction law can be determined from the single empirical
function, H = A/(ln R+)α for α > 0,
just as for boundary layers. The Reynolds number
dependence of the parameters diminishes very slowly with increasing Reynolds
number, and the asymptotic behaviour is reached only when R+ [Gt ] 105.
Planar velocity measurements in compressible mixing layers
Authors: URBAN WILLIAM D. , MUNGAL M. G.
Published: July 2002

In the present study, we use particle image velocimetry (PIV) to obtain planar, two-component velocity fields in two-dimensional, turbulent mixing layers at convective
Mach numbers Mc of 0.25, 0.63, and 0.76. The experiments are performed in a large-scale blowdown wind tunnel, with high-speed free-stream Mach numbers up to 2.25
and shear-layer Reynolds numbers up to 106. Specific issues relating to the application
of PIV to supersonic flows are addressed. The instantaneous data are analysed to
produce maps of derived quantities such as vorticity, and ensemble averaged to
provide turbulence statistics. The results show that compressibility introduces marked
changes in the disposition of instantaneous velocity gradients within the layer, and
hence in the vorticity field. In particular, peak transverse vorticity values are seen
to be confined to thin streamwise sheets under compressible conditions, with little
transverse communication. The location of these sheets near the lab-frame sonic
velocity suggests a sensitivity of the compressible layer to stationary disturbances.
Turbulence statistics derived from the planar velocity measurements confirm previous
observations of strong suppression of transverse velocity fluctuations and primary
Reynolds stress as Mc increases between 0.25 and 0.76.
Effects of heat release on turbulent shear flows.
Part 1. A general equivalence principle for
non-buoyant flows and its application to turbulent jet flames
Authors: TACINA KATHLEEN M. , DAHM WERNER J. A.
Published: July 2002

We address the differences observed due to heat release between reacting and non-reacting versions of otherwise identical shear flows under conditions for which buoyancy
effects are negligible. The differences considered here result from density changes
produced by exothermic reaction, and are shown to be similar to those produced by
free-stream density differences in non-reacting flows. The piecewise linear variations
of temperature with mole fraction allow the density changes due to exothermic reaction
to be related to an equivalent non-reacting flow, in which the temperature of
one of the fluids is raised to an effective value determined by the peak temperature
and overall stoichiometry. This leads to a general equivalence principle by which the
scaling laws for non-reacting flows can be extended to predict effects of heat release
by exothermic reaction. This equivalence principle is then applied to axisymmetric
turbulent jets, where it leads to a generalized momentum diameter d+ in which the
scaling laws for burning and non-burning jets become identical – it effectively extends
the classical momentum diameter d* of Thring & Newby (1953) and Ricou &
Spalding (1961) to exothermic reacting flows. The resulting predicted effects of heat
release, in both the near and far fields, show good agreement with experimental data
from momentum-dominated turbulent jet diffusion flames. The equivalence principle
is then applied to planar turbulent jets, for which it also accurately predicts the
observed effects of combustion heat release.
An experimental investigation of higher-harmonic wave forces on a vertical cylinder
Authors: HUSEBY MORTEN , GRUE JOHN
Published: July 2002

First- and higher-harmonic wave loads on a vertical circular cylinder are investigated
experimentally in a wave tank of small scale. The incoming waves are (periodic) Stokes
waves with wave slope up to 0.24. A large set of waves which are long compared to the
cylinder radius is calibrated. The first seven harmonic components of the measured
horizontal force on the cylinder are analysed. The higher-harmonic forces are significantly
smaller than the first-harmonic force for all wave parameters. The measurements
are continued until the wave amplitude is comparable to the cylinder radius,
where the second-, third- and fourth-harmonic forces become of comparable size.
Comparison with existing perturbation and fully nonlinear models shows, with a few
exceptions, an overall good agreement for small and moderate wave amplitude. A fully
nonlinear model agrees with the experiments even up to the seventh-harmonic force for
part of the amplitude range. For the large amplitudes the models mostly give conservative
predictions. It is important that the distance from the wave maker to the cylinder
is large in order to avoid parasitic effects in the incoming wave field. The limited
width of the wave tank is not important to the results except when close to resonance.
A possible reinterpretation of the Princeton superpipe data
Authors: PERRY A. E. , HAFEZ S. , CHONG M. S.
Published: July 2002

In experiments recently performed at Melbourne, Pitot-tube mean velocity profiles
in a boundary layer disagreed with those obtained with hot wires. The standard
MacMillan (1956) correction for the probe displacement effect and a correction for
turbulence intensity were both required for obtaining agreement between the two
sets of mean velocity data. We were thus motivated to reanalyse the Princeton
superpipe data using the same two corrections. The result is a plausible conclusion
that the superpipe is rough at the higher Reynolds numbers and its data follow the
Colebrook (1939) formula for commercial pipes rather well. It also appears that the
logarithmic law of the wall is valid, with a Kármán constant close to that found
recently by Österlund (1999) from boundary layer measurements with a hot wire. The
smooth regime in the pipe gave almost the same additive constant for the log-law as
Österlund's. A comparison between the superpipe data and the pipe data of Perry,
Henbest & Chong (1997) suggests that the conventional velocity defect law may be
valid down to lower Reynolds numbers than concluded by Zagarola & Smits (1998).
Subcritical, transcritical and supercritical flows

over a step
Authors: ZHANG YINGLONG , ZHU SONGPING
Published: July 2002

Free-surface flow over a bottom topography with an

asymptotic depth change (a ‘step’) is considered

for different ranges of Froude numbers varying from subcritical,

transcritical, to supercritical. For the subcritical case, a linear

model indicates that a train of transient waves propagates upstream

and eventually alters the conditions there. This leading-order

upstream influence is shown to have profound effects on

higher-order perturbation models as well as on the Froude

number which has been conventionally defined in terms of the

steady-state upstream depth. For the transcritical case, a

forced Korteweg–de Vries (fKdV) equation is derived, and the

numerical solution of this equation reveals a surprisingly

conspicuous distinction between positive and negative forcings.

It is shown that for a negative forcing, there exists a

physically realistic nonlinear steady state and our preliminary

results indicate that this steady state is very likely to be

stable. Clearly in contrast to previous findings associated

with other types of forcings, such a steady state in the

transcritical regime has never been reported before. For

transcritical flows with Froude number less than one,

the upstream influence discovered for the subcritical

case reappears.
Turbulence, waves and mixing at shear-free density interfaces.
Part 1. A theoretical model
Authors: FERNANDO H. J. S. , HUNT J. C. R.
Published: July 2002

This paper presents a theoretical model of turbulence and
mixing at a shear-free
stable density interface. In one case (single-sided stirring) the
interface separates a
layer of fluid of density ρ in turbulent motion, with r.m.s.
velocity uH and lengthscale
LH, from a non-turbulent layer with density
ρ+Δρ, while in the second case (double-sided stirring) the lower
layer is also in turbulent motion. In both cases, the external Richardson number
Ri=ΔbLH/
u2H
(where Δb is the buoyancy jump across the
interface) is assumed to be large. Based on the hypotheses that the effect of the
interface on the turbulence is as if it were suddenly imposed (which is equivalent to
generating irrotational motions) and that linear waves are
generated in the interface,
the techniques of rapid distortion theory are used to analyse
the linear aspects of the
distortion of turbulence and of the interfacial motions. New physical concepts are
introduced to account for the nonlinear aspects.

To describe the spectra and variations of the r.m.s. fluctuations
of velocity and displacements, a statistically steady linear model
is used for frequencies above a critical
frequency ωr/μc, where
ωr(=Δb/2uH)
is the maximum resonant frequency and μc<1.
As in other nonlinear systems, observations below this critical
frequency show the existence of long waves on the interface that
can grow, break and cause mixing between
the two fluid layers. A nonlinear model is constructed based on the fact that these
breaking waves have steep slopes (which determines the form of the displacement
spectrum) and on the physical argument that the energy of the
vertical motions of these
dissipative nonlinear waves should be comparable to that of the forced linear waves,
which leads to an approximately constant value for the parameter
μc. The model
predictions of the vertical r.m.s. interfacial velocity, the
interfacial wave amplitude
and the velocity spectra agree closely with new and published experimental results.

An exact unsteady inviscid linear analysis is used to derive the
growth rate of the
full spectrum, which asymptotically leads to the growth of resonant waves and to
the energy transfer from the turbulent region to the wave motion of the stratified
layer. Mean energy flux into the stratified layer, averaged over
a typical wave cycle,
is used to estimate the boundary entrainment velocity for the single-sided stirring
case and the flux entrainment velocity for the double-sided stirring case, by making
the assumption that the ratio of buoyancy flux to dissipation
rate in forced stratified
layers is constant with Ri and has the same value as in
other stratified turbulent flows.
The calculations are in good agreement with laboratory measurements conducted in
mixing boxes and in wind tunnels. The contribution of
Kelvin–Helmholtz instabilities
induced by the velocity of turbulent eddies parallel to the interface
is estimated to be insignificant compared to that of internal waves
excited by turbulence.
The vanishing effect of molecular diffusivity
on turbulent dispersion: implications for
turbulent mixing and the scalar flux
Authors: POPE S. B.
Published: July 2002

In 1921 G. I. Taylor introduced (with little discussion) the
notion that the dispersion
of a conserved passive scalar in a turbulent flow is determined by the
motion of fluid
particles (independent of the molecular diffusivity). Here, a hypothesis
of diffusivity
independence is introduced, which provides a sufficient condition for the
validity
of Taylor's approach. The hypothesis, which is supported by DNS data,
is that,
at high Reynolds number, the mean of the scalar conditional on the velocity
is
independent of the molecular diffusivity. From this hypothesis it is shown
that (at
high Reynolds number) the conditional Laplacian of the scalar is zero.
This new
result has several significant implications for models of turbulent mixing,
and for
the scalar flux. Primarily, a model of turbulent scalar mixing that is
independent of
velocity is inconsistent with the hypothesis, and gives rise to a spurious
source or
(more likely) sink of the scalar flux.
Oblique wave incidence on a plane beach: the classical problem revisited
Authors: EHRENMARK ULF TORSTEN
Published: July 2002

The non-hydrostatic description of three-dimensional waves incident
over a plane
beach at a long straight coastline is considered in terms of the inverse

Kontorovich–Lebedev integral transform. This is seen
as a natural extension to earlier work
by the author where the two-dimensional (normal incidence) flow is expressed
as
an inverse Mellin transform, and similar simplifications in the description
here are
encountered. In particular computations are undertaken for a variety of
beach slopes
of the form α=π/2m where m is an
integer and for a range of incidence angles.
These computations have previously only been practical for beaches whose
slope α is
regarded as asymptotically small thereby allowing versions of the mild-slope
equation
to be used. For the chosen slope angles, the solution is established with
rigour and
methods of estimating near- and far-field asymptotics arise naturally in
this discussion.
For the case of perfect reflection, a previously known solution is recovered
in closed
form as a finite sum of exponential terms, and a shoreline ‘amplification
factor’ aγ is considered for these waves and is computed for a range of beach slopes
through
the entire spectrum of incidence angles. It is shown analytically that,
in the limit of
normal incidence, the value of aγ approaches

the well-known classical result a0=m1/2

and, for glancing incidence, Whitham's (1979) result is confirmed
where the value
approaches either 1 or 0 depending on whether the beach angle is or is
not an angle
at which a new Ursell edge wave mode appears (m odd).

As applications of the new development, comprehensive near-field expansions

for arbitrary reflection are written and verified by computation. These
permit the
construction of refracted wavefronts and wave rays for arbitrary beach
slope without
the usual phase velocity assumptions. Instability is indicated at very
oblique incidence
where nonlinear modelling (Peregrine & Ryrie 1983) predicts
‘anomalous refraction’.
Results are presented graphically and computation of derivatives of the
potential
enables estimation of the (second order) set-down seaward of the
breaker zone. This
is found to decrease as wave attack becomes increasingly oblique.
Instabilities of dynamic thermocapillary liquid
layers with magnetic fields
Authors: MORTHLAND T. E. , WALKER J. S.
Published: July 2002

This paper presents a linear-stability analysis for the transition
from a steady, two-dimensional thermocapillary convection in a liquid-metal layer to a periodic,
three-dimensional flow involving hydrothermal waves which propagate in the directionzw normal to the plane of the base flow. There is a uniform magnetic field
applied
parallel to the free surface in the plane of the base flow, and there is
a linear
temperature gradient along the free surface in the base flow. The ratio
of the layer's
length to its depth, 2L, is large. The magnetic Reynolds number
is small.

A key parameter is λ, the ratio of the large Hartmann number
based on depth to
L. The value of λ increases as either the magnetic field

strength is increased or L is
decreased. The results for very small values of λ agree with the
results of a previous
treatment of this instability without a magnetic field. As λ is
increased, the critical
Marangoni number and the wavenumber for the hydrothermal rolls both increase.

For large values of λ, the base flow and the hydrothermal waves
are confined to a
free-surface layer with O(λ−2) dimensionless
thickness.
Monopolar vortices in an irrotational annular shear flow
Authors: TRIELING R. R. , LINSSEN A. H. , VAN HEIJST G. J. F.
Published: July 2002

The evolution characteristics of monopolar vortices in an irrotational
annular shear
flow were investigated both experimentally and theoretically. The background
flow
was generated in a rotating tank by an appropriate source–sink configuration,
while
the monopolar vortex was created by withdrawing fluid for a short time.
Dye-visualization
studies demonstrated the gradual destruction of the vortex through a
process called ‘vortex stripping’, i.e. long filaments of
passive tracers were being shed
from the edge of the vortex. In contrast to uniform shear flows, these
filaments were
asymmetrically attached to the vortex core. Furthermore, the vortex was
observed to
evolve in a quasi-stationary manner until its final indefinite breaking.
The asymmetric
stripping process could be explained by modelling both the monopolar vortex
and
the ambient flow simply by point vortices, and by adopting the method of
contour
kinematics to trace material contours in the velocity field induced by
the point vortices.
Furthermore, the effect of a continuous spatial vorticity distribution
was investigated
by applying the contour dynamics technique, in which the vortex is represented
by
a stack of uniform vorticity patches. The observed vortex evolution could
be well
captured by this latter approach.
Study of flow in a planar asymmetric diffuser using large-eddy simulation
Authors: KALTENBACH H.-J. , FATICA M. , MITTAL R. , LUND T. S. , MOIN P.
Published: July 2002

Large-eddy simulation (LES) has been used to study the flow in a planar asymmetric
diffuser. The wide range of spatial and temporal scales, the presence of an adverse
pressure gradient, and the formation of an unsteady separation bubble in the rear
part of the diffuser make this flow a challenging test case for assessing the predictive
capability of LES. Simulation results for mean flow, pressure recovery and skin
friction are in excellent agreement with data from two recent experiments. The inflow
consists of a fully developed turbulent channel flow at a Reynolds number based
on shear velocity, Reτ=500. It is found that accurate representation of the in flow velocity field is critical for accurate prediction of the flow in the diffuser. Although the
simulation in the diffuser is well resolved, the subgrid-scale model plays a significant
role for both mean momentum and turbulent kinetic energy balances. Subgrid-scale
stresses contribute a maximum of 8% to the local value of the total shear stress with
the maximum values found in the inlet duct and along the flat wall where the flow
remains attached. The subgrid-scale model adapts to the enhanced turbulence levels
in the rear part of the diffuser by providing more than 80% of the dissipation rate
for turbulent kinetic energy. The unsteady separation excites large scales of motion
which extend over the major part of the duct cross-section and penetrate deeply
into the core of the flow. Instantaneous flow reversal is observed along both walls
immediately behind the diffuser throat which is far upstream of the location of main
separation. While the mean flow profile changes gradually as the flow enters the
expansion, turbulent stresses undergo rapid changes over a short streamwise distance
along the deflected wall. An explanation is offered which considers the strain field as
well as the influence of geometry changes. The effect of grid resolution and spanwise
domain size on the flow field prediction has been documented and this allows an
assessment of the computational requirements for carrying out such simulations.