bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the multiple leaflet gene on agronomical and
physiological characters of mungbean (Vigna radiata)
Authors: KOWSURAT S. , SRINIVES P. , KASEMSAP P. , LAMSEEJAN S.
Published: July 2002

Near-isogenic lines of mungbean (Vigna radiata) were produced from backcrossing two Thai
recommended cultivars, KPS 1 and CN 36, with the multiple leaflet line, V 5926, until BC9. The
isogenic lines were evaluated against the two recipients at Kasetsart University, Thailand, in the rainy
season of 1996 and the dry season of 1997. The effect of the gene controlling the multiple leaflet on
physiological and agronomical characters was investigated. Seed yield, plant height, and number of
pods per plant were greater in the trifoliate leaflet cultivars than in the multiple leaflet near-isogenic
lines, whereas the numbers of seeds per pod and 1000-seed weights were not significantly different.
Light saturation and photosynthetic rate did not differ, while light interception and dry matter
accumulation were greater in the trifoliate leaflet cultivars than in the multifoliate lines. The leaf area
index (LAI) of the trifoliate parents was greater at the vegetative stage but lower at the flowering and
young pod stages, due to the greater number of leaflets per plant of the multifoliate lines. After the
beginning of the podding stage, the LAI of the multifoliate lines was less than that of the parents, as
the number of leaflets per plant of these lines hardly changed while that of the trifoliate parents
increased.
Genetic variability for feeding value of faba bean seeds
(Vicia faba): Comparative chemical composition of
isogenics involving zero-tannin and zero-vicine genes
Authors: DUC G. , MARGET P. , ESNAULT R. , LE GUEN J. , BASTIANELLI D.
Published: July 2002

In a preliminary experiment, 74 faba bean genotypes including winter genotypes (autumn-sown) and
spring genotypes (spring-sown) and isogenic population pairs (tannin-containing v. tannin-free and
vicine/convicine-high v. vicine/convicine-low), were analysed for the chemical composition of their
seeds. A large variability was found for the main constituents (starch, protein and fibre). Autumn-sown genotypes contained 2·3% less proteins but 2·5% more starch in the seed dry matter (DM) than
spring-sown genotypes. The vc− gene, which lowers the vicine and convicine contents, did not
significantly modify the main seed components in the isogenic comparisons. The zt1 and zt2 genes,
which eliminate condensed tannins in the seed coats, lowered by 2·1% the proportion of the seed coat
in the DM. In the isogenic comparisons, the zt2 gene had a stronger effect than zt1 in reducing the
total seed fibre and increasing the protein content.

In a second experiment, from the original 74 genotypes, 12 contrasted genotypes were selected and
multiplied for animal nutrition trials. Their chemical analysis confirmed the variability between the
faba bean categories observed in Expt 1, but detailed chemical analyses illustrated the variability in
amino acid, fatty acid, amylose and oligosaccharide composition, trypsin inhibitory activity,
condensed tannins, lectins and phytic phosphorus contents.
Influence of time of sowing and last cut for fodder on
the fodder and seed yields of Egyptian clover
Authors: SARDANA VIRENDER , SINGH NARWAL SHAMSHER
Published: July 2002

Field investigations were conducted during the winter seasons of 1992/93 and 1993/94 to find the
optimum sowing time and time of last fodder cut for the fodder and seed production of Egyptian
clover (Trifolium alexandrinum L.). The delay in sowing from 1 October to 15 November decreased
the green and dry fodder yields but increased the seed yields. Total green and dry fodder yields (of
all cuttings) for 1 or 15 October sowings were significantly higher than the 15 November sowing in
both years and 1 November sowing in 1992/93. Increase in seed yield from the 15 November sowing
was greater than from the 1 and 15 October sowings. Straw yields followed similar trends. Delay in
the last cut for fodder, however, increased green and dry fodder yields but decreased the seed yield.
The percentage increase in dry fodder yield with each successive delay in last cut for fodder was higher
than that of green fodder yield. The 11 April cutting date of fodder produced the highest green and
dry fodder yields but the lowest seed yield. Two years mean data showed that the 2 March cutting date
of last fodder gave the highest seed yield. It is concluded that higher seed yield of Egyptian clover can
be produced by sowing on 15 November and giving the last fodder cutting on 2 March.
The causes of over-winter plant losses of autumn-sown
white lupins (Lupinus albus) in different regions of the
UK over three seasons
Authors: SHIELD I. F. , SCOTT T. , STEVENSON H. J. , LEACH J. E. , TODD A. D.
Published: July 2002

A series of experiments were carried out at 14 sites in the major arable areas of the UK, in the years
1993–94, 1994–95 and 1995–96 to determine the causes and extent of over-winter plant losses of two
autumn-sown cultivars of white lupin (Lupinus albus L.).

Over the three seasons frost was the major cause of plant losses. Two mechanisms (one known and
one not previously reported in the UK) of frost tolerance under field conditions were identified: (i)
lignification of the root parenchyma early in the life of the seedling, and (ii) a large vernalization
requirement of the main-stem apex, which delays stem elongation in older plants. A model was
developed that could be used to predict the susceptibility of these lupin cultivars to the first severe
frost of the winter using accumulated thermal time (above a base temperature of 3 °C).

The effect of sowing at the beginning or end of a sowing window, calculated to optimize plant
architecture the following summer, therefore varied with the weather during the autumn/winter
period. A combination of cool autumn weather and late sowing (outside of the sowing window)
resulted in plant losses due to a lack of lignification of the root parenchyma. In unusually warm
autumn conditions (1994–95 and 1995–96) plants sown at the beginning of the sowing window were
well developed before the first frosts occurred, with consequent stem elongation and plant losses.

Although losses due to pests were not severe (c. 3 to 5 plants/m2), plants were attacked during the
autumn by grey field slugs (Deroceras reticulatum Muller), bean seed flies (Delia platura Meigen), and
probably thrips (Thrips angusticeps Uzel, Noctuidae), although this has not been confirmed. The
fungal pathogens Fusarium spp. and Botrytis cinerea Pers. caused losses in conjunction with frost
damage.
“Sketches of Spain”: Richard Wright's Pagan Spain and African-American Representations of the Hispanic
Authors: REYNOLDS GUY
Published: July 2002

At the start of Pagan Spain (1957), Richard Wright recalled a 1946
conversation with Gertrude Stein; she encouraged him to visit Spain:
“ ‘You'll see what the Western world is made of. Spain is primitive, but lovely. ’ ” Wright meditated on his fascination with that country, an
obsession rooted in the Civil War's political upheaval: “The fate of Spain
hurt me, haunted me; I was never able to stifle a hunger to understand
what had happened there and why” (PS, 10). Wright wrote as a leftist, as
a political writer who had published anti-Franco articles. In his interest in
Spain, and especially in his “hunger to understand” its fate after the fall
of the Republic, Wright kept company with many mid-century American
artists. Hemingway is the most famous instance of a writer engaged with
Spanish affairs, but forms of Hispanophilia have marked the lives of many
writers and painters. In his account of a trip to Madrid in 1947, Saul
Bellow recalled: “ ‘And then of course I had followed the Spanish Civil
War and knew as much about what had gone on in Spain between 1936–8 as a young American of that time could learn.’ ” At around that time, the
Abstract Expressionist Robert Motherwell was creating his series of
Elegies to the Spanish Republic, a parade of largely black canvases dominated
by oblique representations of archetypal Spanish subjects such as
bullfighting. As Arthur Danto has written of these images: “ ‘Spain’
denotes a land of suffering and poetic violence and political agony, and
‘Elegy’ carries the literary weight of tragedy and disciplined lamentation. ”
Discipline and Punishment in The Adventures of Tom Sawyer
Authors: MESSENT PETER
Published: July 2002

Beltings and beatings play a prominent role in Twain's boy
fictions. In
“The Story of the Bad Little Boy” (1865), Jim is “always
spanked…to
sleep” by his mother and, instead of a good-night kiss, “she
boxed his
ears when she was ready to leave him.” While in Adventures of
Huckleberry
Finn (1884–85), when Huck stays with pap in the cabin in the
woods, “by-and-by
pap got too handy with his hick'ry, and I couldn't stand it.
I was
all over welts.” It is the prevalence of such punishments, and attempted

punishments, in Tom Sawyer's young life that provides the starting-point

for my present analysis of childhood discipline and its fictional
representation in The Adventures of Tom Sawyer (1876). For to
focus on the
different types of punishment Tom undergoes, the supervisory controls
which are placed over him, and the way he responds to them, is to suggest

a reading of Twain's novel as illustrative both of the changing forms
of
domestic discipline being introduced in America in the 1830s and 40s,
and the spaces in which that discipline functions. In pursuing this line
of
inquiry, I build on previous work on the development of modern
American social regulation in the antebellum period, and particularly
that
by G. M. Goshgarian and Richard H. Brodhead.
PROVIDER KNOWLEDGE ABOUT EMERGENCY CONTRACEPTION IN GHANA
Authors: STEINER MARKUS J. , RAYMOND ELIZABETH , ATTAFUAH JOHN D. , HAYS MELISSA
Published: July 2002

In 1996, the Ministry of Health in Ghana included emergency contraception (EC) in its newly issued National Reproductive Health Service Policy and Standards. A short survey was conducted in the summer of 1997 to evaluate health providers' knowledge of EC. Of the 325 providers interviewed, about one-third (34%) had heard of EC. No provider had sufficient knowledge to prescribe EC correctly. A well-coordinated training programme for providers will have to precede successful introduction of EC in Ghana. Moreover, a dedicated product may be critical for the successful introduction of EC in a country like Ghana, where provider knowledge is low.
THE EFFECTS OF WATER SUPPLY AND SANITATION ON CHILDHOOD MORTALITY IN URBAN ERITREA
Authors: WOLDEMICAEL GEBREMARIAM
Published: July 2002

Child mortality differentials according to water supply and sanitation in many urban areas of developing countries suggest that access to piped water and toilet facilities can improve the survival chances of children. The central question in this study is whether access to piped water and a flush toilet affects the survival chance of children under five in urban areas of Eritrea. The study uses data collected by the Demographic and Health Survey (DHS) project in Eritrea in 1995. The results show that while the unadjusted effect of household environment (water supply and toilet facility) is large and statistically significant during the post-neonatal and child periods, it is relatively small and statistically insignificant during the neonatal period. The effect of household environment remains substantial during the post-neonatal and child periods, even when other socioeconomic variables are held constant. However, the household environment effect totally disappears during the neonatal period when the socioeconomic factors are controlled for.
ANALYSIS OF THE VIQ SCORES OF FAMILIES OF THREE OR MORE ORKNEY BROTHERS
Authors: GOODMAN JOAN D. T. , ANDERTON R. B.
Published: July 2002

Classification of the boys in 48 families of three or more brothers
according to their Moray House Test (VIQ) scores awarded at age 11±1½ years in
1947–75 confirms the postulated existence of a total of nine male phenotypes
for this X-linked trait in the score range <70 to 140 points. The phenotypic
means lie close to the sequence 69(8)133. Recombination is shown to occur. An
additive effect of three alleles at each of two X-chromosome loci is the most
likely simple scheme. An iterative approach matching the observed mixtures of
proposed genotypes in the families with probabilities for variable levels of
homozygosity, non-crossover/crossover heterozygosity, and maternal meiotic
recombination yields a best goodness of fit where this last is 20%.
HOUSING AND ENVIRONMENTAL FACTORS AND THEIR EFFECTS ON THE HEALTH OF CHILDREN IN THE SLUMS OF KARACHI, PAKISTAN
Authors: D'SOUZA RENNIE M.
Published: July 2002

To examine the association of environmental factors (including housing) with respiratory infections and diarrhoea in children under 5 years of age, a cross-sectional study of 403 families was conducted in a squatter settlement of Karachi. In the 2-week period before the survey prevalence of diarrhoea and respiratory infections was 14·4% and 15·0% respectively. The factors significantly associated (p>0·05) with diarrhoea in households in the multivariate analysis were: number of children under 5, regular cleaning of sewers, storage of water in small utensils and cooking inside a one room house. Five households risk factors were identified for respiratory infections: the number of children under 5, poor housing structure, increased household density, humidity inside the house less than the humidity outside house, and frequent cooking inside the house. These results suggest that children under 5 years of age in lower income areas are at additional risk to health because of poor environmental conditions.
PROBABILITIES OF MARRIAGE IN TWO OUTER HEBRIDEAN ISLANDS, 1861–1990
Authors: CLEGG E. J.
Published: July 2002

A study has been made of the probabilities of marriage of females and males aged 15–49 (either as a whole or in 5-year age groups) in two Outer Hebridean islands, Harris and Barra. The results were compared with ages of marriage and with the frequencies of permanent celibacy. The marriages took place between 1861 and 1990.

Median ages of marriage rose to maxima in the 1930s and 1940s, then fell steeply, levelling out latterly. Permanent celibacy was consistently high among females, but rose from much lower levels in males to maxima in the 1970s and 1980s. It is concluded that in these populations age at marriage and the extent of permanent celibacy are largely independent of one another.

In both islands the overall probabilities of females marrying fell until the 1920s, and then rose. The last decades showed stability (Barra) and a fall (Harris). Males showed only slight falls to about 1910; data were absent for between 1911 and 1960, but subsequently there was little rise in probability.

These overall changes seemed to be associated with reciprocal variations in probabilities in the younger and older age groups. Declining overall probabilities were associated with declines in younger and increases in older age-group probabilities, and vice versa.

Non-parametric correlations between median ages of marriage and probability of marriage were negative and generally significant for the 15–19 age group. Among the older age groups coefficients were generally positive.

There was some evidence of an association between probability of marriage and sex ratio in any group of potential mates. The effect appeared more marked among 15- to 19-year-old females.

Local factors which might explain at least part of the decline in nuptiality for the greater part of the period under study include the decline in the fishing industry and the ‘land hunger’ which existed until the late 1920s. This decline is interpreted as a ‘Malthusian’ response to economic and social conditions, but it coexisted with a ‘neo-Malthusian’ strategy, in the shape of declining marital fertility. The ‘Malthusian’strategy seems to have been largely abandoned around the 1950s, but it may have reappeared during the 1980s.
Formation kinetics of hydroxymethylfurfural, lactulose and furosine in milk heated under isothermal and non-isothermal conditions
Authors: CLAEYS WENDIE L. , LUDIKHUYZE LINDA R. , HENDRICKX MARC E.
Published: July 2002

A detailed kinetic study of hydroxymethylfurfural, lactulose and furosine formation was performed upon heating milk at temperatures between 90 °C and 140 °C. In case of prolonged heating, formation kinetics could be described by a fractional conversion model. Considering only the first phase of the model, kinetics could be simplified to a pseudo-zero order model. A first assessment of kinetic parameters was made by isothermal experiments. Data were analysed using both a 2-step linear and a 1-step non-linear regression method. Only for furosine, did the global 1-step regression approach seem to give better results than the individual 2-step regression approach. Next, the estimated parameters kref and Ea were re-evaluated under non-isothermal conditions by subjecting milk to a time variable temperature profile. Given the complexity of Maillard reaction, it seemed better to estimate kinetic parameters under non-isothermal conditions when using a simplified model. Formation of hydroxymethylfurfural, lactulose and furosine was characterized by an Ea value of 90·2 kJ/mol (k110 °C = 1·2 μmol/l, min), 99·1 kJ/mol (k110 °C = 51·5 mg/l, min) and 88·7 kJ/mol (k110 °C = 16·3 mg/100 g protein, min) respectively. Additionally, 90% joint confidence regions were constructed in order to obtain an accurate representation of the statistical confidence associated with the simultaneously estimated parameters.
Method for the measurement of lipase activity in milk
Authors: HUMBERT GERARD , GUINGAMP MARIE-FRANCE , LINDEN GUY
Published: July 2002

Lipolysis has many effects in dairy technology. Undesirable
consequences include deleterious effects on the organoleptic properties of milk
and some cheeses; however, it is desirable in some other cheeses.

The usual methods for detecting lipolysis in milk measure the amounts of free
fatty acids liberated from triacylglycerols (International Dairy Federation, 1991).
Lipase activity is detected by incubation of samples with substrates such as
tributyrin (Castberg et al. 1975) or triolein (Nilsson-Ehle &
Schotz, 1976; Shirai et al.
1982). A few reports describe methods using synthetic chromogenic substrates, e.g.
p-nitrophenyl butyrate (Shirai & Jackson, 1982), β-naphthyl
caprylate (McKellar,
1986; McKellar & Cholette, 1986) or 4-methylumbelliferyl oleate (Stead, 1983).
Tsakalidou et al. (1992) have developed the detection of
esterase activities on electrophoresis gels.
Structural features of a peptide corresponding to human κ-casein
residues 84–101 by 1H-nuclear magnetic resonance spectroscopy
Authors: PLOWMAN JEFFREY E. , CREAMER LAWRENCE K. , LIDDELL MICHAEL J. , CROSS JENNIFER J.
Published: July 2002

The peptide Val–Arg–Arg–Pro–Asn–Leu–His–Pro–Ser–Phe–Ile–Ala–Ile–Pro–Pro–Lys–Lys–Ile, which corresponds to residues 84–101 of human κ-casein, has been synthesized and its conformation preferences determined by 1H-nuclear magnetic resonance spectroscopy in dimethyl sulphoxide. The peptide adopted a largely extended chain conformation in solution and there was evidence for the presence of a β-turn involving residues Pro87–His90 of human κ-casein. The presence of a turn in this position would make the physiologically significant Arg85 residue of human κ-casein (which is equivalent to Arg97 in bovine κ-casein) unavailable for interaction with Asp249of bovine chymosin, and may partly explain why human κ-casein is hydrolysed more slowly than its bovine counterpart by bovine chymosin.
Purification and characterization of a lysine-p-nitroanilide hydrolase,
a broad specificity aminopeptidase, from the cytoplasm of
Lactococcus lactis subsp. cremoris AM2
Authors: McDONNELL MAEVE , BOUCHIER PAUL , FITZGERALD RICHARD J. , O'CUINN GERARD
Published: July 2002

A hydrolase activity that cleaves lysyl-p-nitroanilide (Lys-pNA) has
been purified from the cytoplasm of Lactococcus lactis subsp. cremoris AM2 by
chromatography on DE52, DEAE Affi-Gel Blue Gel, Hydroxyapatite Bio-Gel HTP
and Phenyl Sepharose. The purified aminopeptidase was found to have
a native Mr
of 50 000–55 000 by gel filtration chromatography and by FPLC gel filtration on
Superose 12 and to be composed of a single polypeptide chain following SDS-PAGE.
Enzyme activity was almost completely inhibited by EDTA, amastatin, puromycin
and bestatin, while the sulphydryl-reactive agents p-chloromercuribenzoate and
iodoacetamide were inhibitory. The enzyme was found to be very unstable during the
purification procedures at 4°C and its stability was greatly improved when 10 ml
glycerol/l and 2 mm-dithiothreitol were included in the purification buffers. The
purified enzyme was found to hydrolyse a wide range of dipeptides, tripeptides and
longer peptides provided that proline was not present in the penultimate position
from the N-terminus or that a pyroglutamyl residue was not present at the
N-terminus. While neither Asp-pNA nor Pro-pNA was hydrolysed by the purified
enzyme, the release of N-terminal acidic residues from peptides was observed in
addition to the release of N-terminal proline from Pro–Leu–Gly–NH2,
Pro–Leu–Gly–Gly and Pro–His–Pro–Phe–His–Leu–Phe–Val–Tyr. This ability of Lys-pNA
hydrolase to release N-terminal proline residues was employed in concert with a
purified aminopeptidase P preparation to release alternate N-terminal amino acids
from Tyr–Pro–Phe–Pro–Gly. The complementary action of these enzymes represents
an alternative mechanism to that of post-proline dipeptidyl aminopeptidase for
metabolism of proline-containing peptides.
Rotary honing: a variant of the Taylor paint-scraper problem
Authors: HILLS CHRISTOPHER P. , MOFFATT H. K.
Published: July 2002

The three-dimensional flow in a corner of fixed angle α induced by the rotation in
its plane of one of the boundaries is considered. A local similarity solution valid
in a neighbourhood of the centre of rotation is obtained and the streamlines are
shown to be closed curves. The effects of inertia are considered and are shown to be
significant in a small neighbourhood of the plane of symmetry of the flow. A simple
experiment confirms that the streamlines are indeed nearly closed; their projections on
planes normal to the line of intersection of the boundaries are precisely the ‘Taylor’
streamlines of the well-known ‘paint-scraper’ problem. Three geometrical variants
are considered: (i) when the centre of rotation of the lower plate is offset from the
contact line; (ii) when both planes rotate with different angular velocities about a
vertical axis and Coriolis effects are retained in the analysis; and (iii) when two
vertical planes intersecting at an angle 2β are honed by a rotating conical boundary.
The last is described by a similarity solution of the first kind (in the terminology of
Barenblatt) which incorporates within its structure a similarity solution of the second
kind involving corner eddies of a type familiar in two-dimensional corner flows.
Dynamics of cooling domes of viscoplastic fluid
Authors: BALMFORTH N. J. , CRASTER R. V.
Published: July 2002

A non-isothermal viscoplastic thin-layer theory is developed to explore the effects of
surface cooling, yield stress, and shear thinning on the evolution of non-isothermal
domes of lava and laboratory fluids. The fluid is modelled using the Herschel–Bulkley
constitutive relations, but modified to have temperature-dependent viscosity
and yield stress. The thin-layer equations are solved numerically to furnish models
of expanding, axisymmetrical domes. Linear stability theory reveals the possibility of
non-axisymmetrical, fingering-like instability in these domes. Finally, the relevance to
lava and experiments is discussed.
Direct numerical simulation of a three-dimensional spatially developing bubble-laden mixing layer with two-way coupling
Authors: DRUZHININ O. A. , ELGHOBASHI S. E.
Published: July 2002

Direct numerical simulations (DNS) of a three-dimensional spatially-developing mixing
layer (ML) laden with spherical gaseous bubbles are performed, with both one-way
and two-way coupling between the two phases. Forcing is used to initialize the
spanwise vortex roll-up and to create a pair of counter-rotating streamwise vortices,
rendering the carrier flow three-dimensional. The characteristics of the resulting ML
flow field are similar to those reported in numerous experimental and numerical studies.
The volume fraction (or concentration) of the bubble phase is considered small
enough to neglect bubble–bubble interactions. The no-slip fluid velocity condition
is assumed at the bubble surface, and the bubble Reynolds number is less than 1
throughout the simulation time. The two-fluid formulation (TF) is used to compute
the bubble-phase velocity and concentration and the two-way coupling source term
in the fluid momentum equation. A Lagrangian–Eulerian mapping (LEM) solver is
employed to solve the equations for the bubble velocity and concentration. LEM is
capable of resolving the gradients of concentration created by the bubble preferential
accumulation without numerical instabilities. Two different inflow profiles (Cref(z)) of
bubble-phase concentration are considered: a uniform profile and a tanh-profile. In
the latter case, the high-speed (upper) stream is devoid of bubbles, and the low-speed
(lower) stream is uniformly laden with bubbles at the inflow plane.

The DNS results show that in addition to the well-known preferential accumulation
of bubbles in the vortex centres, sheets of increased bubble concentration (C-sheets)
develop in the rollers created by the vortex pairing in the ML core, with two local
maxima of vorticity and an enhanced strain-rate field. The development of C-sheets
is governed by the stretching and contraction along the principal axes of the local
strain rate.

In the case of uniform Cref, the two-way coupling reduces the average ML vorticity
thickness and the entrainment of the irrotational fluid into the ML core, as compared
to the bubble-free case, upstream of the location of the first vortex pairing. However,
both ML vorticity thickness is increased and entrainment is enhanced by the bubbles
farther downstream, after the pairing. The fluid velocity fluctuations are reduced by
the bubbles throughout the ML, as compared to the one-way coupling case.

In the case of the tanh-profile of Cref, the velocity fluctuations and the ML vorticity
thickness are increased by the bubbles upstream the location of the first vortex pairing
owing to the ‘unstable’ inflow bubble stratification (Druzhinin & Elghobashi 1998).
On the other hand, the velocity fluctuations are reduced by the bubbles, and the ML
vorticity thickness oscillates with the streamwise distance farther downstream.
Shock unsteadiness in a reattaching shear layer
Authors: POGGIE J. , SMITS A. J.
Published: July 2002

The origin of shock unsteadiness in a Mach 2.9 turbulent reattaching shear layer was
investigated experimentally using temporally resolved flow visualization and measurements
of wall pressure fluctuations. In this flow, the separation point of a turbulent
boundary layer is essentially fixed at a backward-facing step, and the reattachment
point is free to move along a ramp. In order to examine the influence of disturbances
originating in the incoming shear layer, artificial disturbances were introduced into
the flow through steady air injection in the vicinity of separation. The effect on the
reattachment shock system was dramatic: the intensity of the pressure fluctuations
and the amplitude of the shock motion increased substantially, and power spectra
of the pressure fluctuations showed a distinct shift to lower frequency. The spectra
collapsed onto a common curve in non-dimensional coordinates based on a length
scale derived from two-point cross-correlations of the flow visualization data and
a convection velocity derived from cross-correlations of the pressure measurements.
The data were compared to a theory developed by Plotkin (1975), which is based
on perturbation of a shock by random fluctuations in the incoming turbulent flow.
Plotkin's model mimics the manner in which relatively broad-band perturbations in
the incoming turbulent flow lead to relatively low-frequency motion of the separation
bubble and its associated shock system. It is an excellent fit to separation shock
motion, such as that generated in a blunt fin flow (briefly illustrated here). In the
present shear layer flow, this low-frequency motion was detectable in the spectra near
reattachment, but contained considerably less energy relative to the shock motions
caused by direct perturbations by the incoming turbulent structures. These results
indicate that the shock motion in the reattaching shear layer is primarily caused by
organized structures in the incoming turbulent flow.
Scaling and parameterization of stratified homogeneous turbulent shear flow
Authors: SHIH LUCINDA H. , KOSEFF JEFFREY R. , FERZIGER JOEL H. , REHMANN CHRIS R.
Published: July 2002

Homogeneous sheared stratified turbulence was simulated using a DNS code. The
initial turbulent Reynolds numbers (Re) were 22, 44, and 89, and the initial dimensionless
shear rate (S*) varied from 2 to 16. We found (similarly to Rogers (1986) for
unstratified flows) the final value of S* at high Re to be ∼ 11, independent of initial
S*. The final S* varies at low Re, in agreement with Jacobitz et al. (1997). At low Re,
the stationary Richardson number (Ris) depends on both Re and S*, but at higher
Re, it varies only with Re. A scaling based on the turbulent kinetic energy equation
which suggests this result employs instantaneous rather than initial values of flow
parameters.

At high Re the dissipation increases with applied shear, allowing a constant final S*.
The increased dissipation occurs primarily at high wavenumbers due to the stretching
of eddies by stronger shear. For the high-Re stationary flows, the turbulent Froude
number (Frt) is a constant independent of S*. An Frt-based scaling predicts the final
value of S* well over a range of Re. Therefore Frt is a more appropriate parameter for
describing the state of developed stratified turbulence than the gradient Richardson
number.
Reynolds-averaged equations for free-surface flows with application to high-Froude-number jet spreading
Authors: HONG WEN-LING , WALKER DAVID T.
Published: July 2002

The goals of this study were to develop a set of Reynolds-averaged governing equations
for turbulent free-surface flow, and to use the resulting equations to determine
the origin of the surface current in high-Froude-number jet flows. To develop the
Reynolds-averaged equations, free-surface turbulent flow is treated as a two-fluid
flow separated by an interface. It is shown that the general Navier–Stokes equations
written for variable property flow embody the field equations applicable to each fluid,
as well as the boundary conditions for the interface and, therefore, can be applied
across the entire fluid domain, including the interface. With this as a starting point, a
formulation of the Reynolds-averaged governing equations for turbulent free-surface
flows can be developed rigorously. The resulting Reynolds-averaged equations are
written in terms of density-weighted averages, their derivatives, and the probability
density function for the free-surface position. These equations are similar to the
conventional Reynolds-averaged equations, but include additional terms which represent
the average effect of the forces acting instantaneously on the free surface,
forces normally associated with the boundary conditions. These averaged equations
are applied to the interaction of a turbulent jet with the free surface in order to
establish, for arbitrary-Froude-number flows, the origin of the surface current, the
large outward velocity which occurs in a thin layer adjacent to the surface. It is shown
via an order-of-magnitude analysis that the outward acceleration associated with the
surface current results from a combination of the Reynolds-stress anisotropy and
the free-surface fluctuations. For low Froude number, the surface current is mainly
driven by the Reynolds stress anisotropy, consistent with the results of Walker (1997);
when the Froude number is large, the Reynolds-stress anisotropy is smaller and the
free-surface fluctuations make a significant contribution.
Statistical evidence of hairpin vortex packets in wall turbulence
Authors: CHRISTENSEN K. T. , ADRIAN R. J.
Published: July 2002

The structure of velocity in the outer region of turbulent channel flow
(y+ [gsim ] 100) is
examined statistically to determine the average flow field associated with spanwise
vortical motions. Particle image velocimetry measurements of the streamwise and wall-normal velocity components are correlated with a vortex marker (swirling strength) in
the streamwise–wall-normal plane, and linear stochastic estimation is used to estimate
the conditional average of the two-dimensional velocity field associated with a swirling
motion. The mean structure consists of a series of swirling motions located along a
line inclined at 12°–13° from the wall. The pattern is consistent with the observations
of outer-layer wall turbulence in which groups of hairpin vortices occur aligned in the
streamwise direction. While the observational evidence for the aforementioned model
was based upon both experimental and computational visualization of instantaneous
structures, the present results show that, on average, the instantaneous structures occur
with sufficient frequency, strength, and order to leave an imprint on the statistics of
the flow as well. Results at Reτ = 547 and 1734 are presented.
Flow structures and particle deposition patterns in double-bifurcation airway models.
Part 1. Air flow fields
Authors: COMER J. K. , KLEINSTREUER C. , ZHANG Z.
Published: July 2002

The understanding and quantitative assessment of air flow fields and local micron-particle wall concentrations in tracheobronchial airways are very important for estimating
the health risks of inhaled particulate pollutants, developing algebraic transfer
functions of global lung deposition models used in dose-response analyses, and/or
determining proper drug-aerosol delivery to target sites in the lung. In this paper (Part
1) the theory, model geometries, and air flow results are provided. In a companion
paper (Part 2, Comer et al. 2001), the history of particle deposition patterns and
comparisons with measured data sets are reported. Decoupling of the naturally dilute
particle suspension makes it feasible to present the results in two parts.

Considering a Reynolds number range of 500 [les ] ReD [les ] 2000, it is assumed that
the air flow is steady, incompressible and laminar and that the tubular double bifurcations,
i.e. Weibel's generations G3–G5, are three-dimensional, rigid, and smooth
with rounded as well as sharp carinal ridges for symmetric planar, and just rounded
carinas for 90° non-planar configurations. The employed finite-volume code CFX
(AEA Technology) and its user-enhanced FORTRAN programs were validated with
experimental velocity data points for a single bifurcation. The resulting air flow
structures are analysed for relatively low (ReD = 500) and high
(ReD = 2000) Reynolds
numbers. Sequential pressure drops due to viscous effects were calculated and compared,
extending a method proposed by Pedley et al. (1977). Such detailed results for
bifurcating lung airways are most useful in the development of global algebraic lung
models.
Experimental investigation of the vorticity generation within a

spilling water wave
Authors: DABIRI DANA , GHARIB MORTEZA
Published: July 2002

Sources of vorticity are examined for a laboratory-generated

spilling breaking wave. Two cases are studied. For the first case,

based on the breaker height, the Reynolds and Froude numbers are 7370

and 2.04, respectively. The breaker is preceded by 1 mm wavelength

capillary waves, with the largest amplitude-to-wavelength ratio equal

to 0.18. For this case, it is found that the dominant source of

vorticity flux is a viscous process, due to the deceleration of a

thin layer of the surface fluid. For the second case, the Reynolds

and Froude numbers based on the wave height are 1050 and 1.62,

respectively. No breaking is observed for this case; rather a

capillary–gravity wave is observed with 4 mm wavelength

capillaries preceding the gravity wave. The largest

amplitude-to-wavelength ratio of these capillaries is 0.28. This case

shows that capillary waves do not contribute to the vorticity flux;

rather the only dominant source of the vorticity flux into the flow

is the free-surface fluid deceleration.

Lastly, a thin free-surface jet that is relatively vorticity-free

is found to precede the spilling breaker. Analyses suggest that our

wave-breaking phenomena can be modelled by a hydraulic jump

phenomenon where the Froude number is based on the thickness of the

free-surface jet, and on the velocity of the free-surface jet just

prior to breaking. We believe this to be a more physically

descriptive value of the Froude number. For the high-speed case, the

Froude number based on the thickness of the free-surface jet is 4.78,

while for the lower-speed case it is 2.14.
Regimes of coalescence and separation in droplet collision
Authors: QIAN J. , LAW C. K.
Published: July 2002

An experimental investigation of the binary droplet collision
dynamics was conducted, with emphasis on the transition between
different collision outcomes. A series of time-resolved photographic
images which map all the collision regimes in terms of the collision
Weber number and the impact parameter were used to identify the
controlling factors for different outcomes. The effects of liquid and
gas properties were studied by conducting experiments with both water
and hydrocarbon droplets in environments of different gases (air,
nitrogen, helium and ethylene) and pressures, the latter ranging from
0.6 to 12 atm. It is shown that, by varying the density of the gas
through its pressure and molecular weight, water and hydrocarbon
droplets both exhibit five distinct regimes of collision outcomes,
namely (I) coalescence after minor deformation, (II) bouncing, (III)
coalescence after substantial deformation, (IV) coalescence followed
by separation for near head-on collisions, and (V) coalescence
followed by separation for off-centre collisions. The present result
therefore extends and unifies previous experimental observations,
obtained at one atmosphere air, that regimes II and II do not exist
for water droplets. Furthermore, it was found that coalescence of the
hydrocarbon droplets is promoted in the presence of gaseous
hydrocarbons in the environment, suggesting that coalescence is
facilitated when the environment contains vapour of the liquid mass.
Collision at high-impact inertia was also studied, and the mechanisms
for separation of the coalescence are discussed based on
time-resolved collision images. A coalescence/separation
criterion defining the transition between regimes III and IV for the
head-on collisions was derived and found to agree well with the
experimental data.
Scattering of sound waves by a cylindrical vortex: a

semi-analytical theory
Authors: REINSCHKE J. , MÖHRING W. , OBERMEIER F.
Published: July 2002

A semi-analytical theory for the scattering of plane sound

waves by a compressible, non-homentropic, circular-cylindrical, single

vortex is presented in this paper. As a special case, the scattering

of sound by a cylindrical inhomogeneity (hot spot) is investigated.

Contrary to the otherwise analogous quantum-mechanical scattering

problem, there are singularities in the modified acoustic wave

equation for radii xs ∈ (0, ∞)

when the scattering by a vortex is considered. It will be shown how

these singularities can be treated.

This sound-scattering theory is

applied to the problem of the interaction of weak plane shock waves

with a strong cylindrical vortex. The calculated scattered sound

signal has a rather complicated structure in which a cylindrical

wave with an essentially quadrupolar directivity pattern is

discernible. In the case of shock–hot-spot interaction a

scattered sound signal with dipole-like amplitude is obtained. Both

results qualitatively agree with experimental findings.
Free-surface effects on spin-up in a rectangular tank
Authors: VAN DE KONIJNENBERG J. A. , VAN HEIJST G. J. F.
Published: July 2002

The dependence of spin-up in a rectangular tank on deformation
of the

free surface is investigated experimentally. The results agree with earlier

experimental and numerical data about the motion of vortices over topography.

However, the presence of sidewalls

appears to interact with the vortex drift induced by the surface topography.
This

combined effect provides a qualitative explanation for the observed behaviour
of

individual vortices. In particular, in the presence of free-surface deformation,

cyclonic vortices in an elongated rectangle tend to drift away from the
centre of

the tank, so that their merging in the centre is discouraged.
On the theory of electrohydrodynamically driven

capillary jets
Authors: GAÑÁN-CALVO ALFONSO M.
Published: July 2002

Electrohydrodynamically (EHD) driven capillary jets are analysed
in this

work in

the parametrical limit of negligible charge relaxation effects, i.e. when

the electric

relaxation time of the liquid is small compared to the hydrodynamic times.
This

regime can be found in the electrospraying of liquids when Taylor's
charged

capillary

jets are formed in a steady regime. A quasi-one-dimensional EHD model comprising

temporal balance equations of mass, momentum, charge, the capillary balance
across

the surface, and the inner and outer electric fields equations is presented.

The steady

forms of the temporal equations take into account surface charge convection
as well

as Ohmic bulk conduction, inner and outer electric field equations, momentum
and

pressure balances. Other existing models are also compared. The propagation
speed

of surface disturbances is obtained using classical techniques. It is shown

here that,

in contrast with previous models, surface charge convection provokes a
difference

between the upstream and the downstream wave speed values, the upstream
wave

speed, to some extent, being delayed. Subcritical, supercritical and convectively

unstable regions are then identified. The supercritical nature of the microjets

emitted

from Taylor's cones is highlighted, and the point where the jet switches

from a stable

to a convectively unstable regime (i.e. where the propagation speed of
perturbations

become zero) is identified. The electric current carried by those jets
is

an eigenvalue

of the problem, almost independent of the boundary conditions downstream,
in an

analogous way to the gas flow in convergent–divergent nozzles exiting
into

very low

pressure. The EHD model is applied to an experiment and the relevant physical

quantities of the phenomenon are obtained. The EHD hypotheses of the model
are

then checked and confirmed within the limits of the one-dimensional assumptions.
Flow past periodic arrays of spheres at low

Reynolds number
Authors: CHENG HONGWEI , PAPANICOLAOU GEORGE
Published: July 2002

We calculate the force on a periodic array of spheres in a viscous
flow

at small

Reynolds number and for small volume fraction. This generalizes the known
results

for the force on a periodic array due to Stokes flow (zero Reynolds number)
and the

Oseen correction to the Stokes formula for the force on a single sphere
(zero volume

fraction). We use a generalization of Hasimoto's approach that is
based on an

analysis of periodic Green's functions. We compare our results to
the

phenomenological ones of Kaneda for viscous flow past a random array

of spheres.
Breaking waves and the equilibrium range of wind-wave spectra
Authors: BELCHER S. E. , VASSILICOS J. C.
Published: July 2002

When scaled properly, the high-wavenumber and high-frequency parts
of

wind-wave spectra collapse onto universal curves. This collapse has been

attributed to a

dynamical balance and so these parts of the spectra have been called the
equilibrium

range. We develop a model for this equilibrium range based on kinematical
and

dynamical properties of breaking waves. Data suggest that breaking waves
have high

curvature at their crests, and they are modelled here as waves with discontinuous

slope at their crests. Spectra are then dominated by these singularities
in slope.

The equilibrium range is assumed to be scale invariant, meaning that there
is no

privileged lengthscale. This assumption implies that: (i) the sharp-crested
breaking

waves have self-similar shapes, so that large breaking waves are magnified
copies of

the smaller breaking waves; and (ii) statistical properties of

breaking waves, such as

the average total length of breaking-wave fronts of a given scale,

vary with the scale

of the breaking waves as a power law, parameterized here with exponent
D.
Boundary-layer receptivity for a parabolic leading edge. Part 2.

The small-Strouhal-number limit
Authors: HAMMERTON P. W. , KERSCHEN E. J.
Published: July 2002

In Hammerton & Kerschen (1996), the effect of the

nose radius of a body on

boundary-layer receptivity was analysed for the case of a symmetric mean
flow

past a two-dimensional body with a parabolic leading edge. A low-Mach-number

two-dimensional flow was considered. The radius of curvature of

the leading edge, rn,

enters the theory through a Strouhal number,

S=ωrn/U, where
ω

is the frequency of

the unsteady free-stream disturbance and U is the mean flow speed.

Numerical results

revealed that the variation of receptivity for small S was very

different for free-stream

acoustic waves propagating parallel to the mean flow and those free-stream
waves

propagating at an angle to the mean flow. In this paper the

small-S asymptotic theory

is presented. For free-stream acoustic waves propagating parallel to the
symmetric

mean flow, the receptivity is found to vary linearly with S,

giving a small increase

in the amplitude of the receptivity coefficient for small S compared

to the flat-plate

value. In contrast, for oblique free-stream acoustic waves, the receptivity

varies with

S1/2, leading to a sharp decrease in the amplitude

of the receptivity coefficient relative

to the flat-plate value. Comparison of the asymptotic theory with numerical
results

obtained in the earlier paper confirms the asymptotic results but reveals
that the

numerical results diverge from the asymptotic result for unexpectedly small
values

of S.
Drag on fixed beds of fibres in slow flow
Authors: HOWELLS I. D.
Published: July 2002

As a sequel to earlier work on viscous flow
through random beds of fixed spheres, the
flow through beds of fixed cylindrical fibres is studied
by the same method. Several
distributions of orientation are considered. The aim is to
find the shielding radius and
drag per unit length as a function of volume fraction
occupied by the fibres, in the semi-dilute situation.
The first approximation is obtained from the drag on a very long
cylinder resulting from the uniform flow at infinity of a
viscous fluid in the presence of
Darcy resistance. Estimates are made of the effects of
finite length, and of curvature of
the fibres. Finally the effect of a neighbouring cylinder is
considered, to obtain the
second-stage approximation for straight fibres.
Comparison is made with some
experimental and numerical results for unidirectional fibres
and for plane pads.