bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-layer thermal convection in miscible
viscous fluids
Authors: DAVAILLE ANNE 
Published: July 2002

The influence of a viscosity stratification on the interaction
between thermal convection
and a stable density discontinuity is studied, using laboratory experiments.

Initially, two superposed isothermal layers of high-Prandtl-number miscible
fluids are
suddenly cooled from above and heated from below. By adjusting the concentrations

of salt and cellulose, Rayleigh numbers between 300 and 3×107

were achieved for density contrasts between 0.45 % and 5 % and
viscosity ratios between 1 and 6.4×104.
Heat and mass transfer through the interface were monitored.Two-layer convection is observed but a steady state is never obtained
since penetrative
convection occurs. A new interfacial instability is reported, owing to
the
nonlinear interaction of the unstable thermal and stable chemical density
gradients.
As a result, the temperature condition at the interface is highly inhomogeneous,

driving, on top of the classical small-scale thermal convection, a large-scale
flow in each
layer which produces cusps at the interface. Entrainment, driven by viscous
coupling
between the two layers, proceeds through those cusps. The pattern of entrainment
is
asymmetric: two-dimensional sheets are dragged into the more viscous layer,
while
three-dimensional conduits are produced in the less viscous layer. A simple
entrainment
model is proposed and scaling laws for the entrainment rate are derived;
they
explain the experimental data well.
Insoluble surfactants on a drop in an extensional

flow: a generalization of the stagnated surface

limit to deforming interfaces
Authors: EGGLETON CHARLES D. , PAWAR YASHODHARA P. , STEBE KATHLEEN J. 
Published: July 2002

A drop in an axisymmetric extensional ow is studied using boundary integral

methods to understand the effects of a monolayer-forming surfactant on a strongly

deforming interface. Surfactants occupy area, so there is an upper bound to the

surface concentration that can be adsorbed in a monolayer, Γ∞.

The surface tension is a highly nonlinear function of the surface concentration

Γ because of this upper

bound. As a result, the mechanical response of the system varies strongly with

Γ for realistic material parameters. In this work, an insoluble surfactant is

considered in the limit where the drop and external fluid viscosities are equal.For Γ<Γ∞, surface convection sweeps

surfactant toward the drop poles. When surface diffusion is negligible, once the stable drop

shapes are attained, the interface

can be divided into stagnant caps near the drop poles, where

Γ is non-zero, and

tangentially mobile regions near the drop equator, where the surface concentration is

zero. This result is general for any axisymmetric fluid particle. For

Γ near Γ∞, the

stresses resisting accumulation are large in order to prevent the local concentration

from reaching the upper bound. As a result, the surface is highly stressed tangentially

while Γ departs only slightly from a uniform distribution. For this case,

Γ is never zero, so the tangential surface velocity is zero for

the steady drop shape.This observation that Γ dilutes nearly uniformly for high surface

concentrations is used to derive a simplified form for the surface mass balance that applies in

the limit of high surface concentration. The balance requires that the tangential flux

should balance the local dilatation in order that the surface concentration profile will

remain spatially uniform. Throughout the drop evolution, this equation yields results

in agreement with the full solution for moderate deformations, and underscores the

dominant mechanism at high deformation. The simplified balance reduces to the

stagnant interface condition at steady state.Drop deformations vary non-monotonically with concentration; for

Γ<Γ∞, the

reduction of the surface tension near the poles leads to higher deformations than the

clean interface case. For Γ near Γ∞,

however, Γ dilutes nearly uniformly, resulting in

higher mean surface tensions and smaller deformations. The drop contribution to the

volume averaged stress tensor is also calculated and shown to vary non-monotonically

with surface concentration.
Drag and lift forces on a rotating sphere in a linear shear flow
Authors: KUROSE RYOICHI , KOMORI SATORU 
Published: July 2002

The drag and lift forces acting on a rotating rigid sphere in a
homogeneous linear shear
flow are numerically studied by means of a three-dimensional numerical
simulation.
The effects of both the fluid shear and rotational speed of the sphere
on the drag and
lift forces are estimated for particle Reynolds numbers of
1[les ]Rep[les ]500.The results show that the drag forces both on a stationary sphere in
a linear shear
flow and on a rotating sphere in a uniform unsheared flow increase with
increasing
the fluid shear and rotational speed. The lift force on a stationary sphere
in a linear
shear flow acts from the low-fluid-velocity side to the high-fluid-velocity
side for low
particle Reynolds numbers of Rep<60,
whereas it acts from the high-velocity side to
the low-velocity side for high particle Reynolds numbers of
Rep>60. The change of
the direction of the lift force can be explained well by considering the
contributions of
pressure and viscous forces to the total lift in terms of flow separation.
The predicted
direction of the lift force for high particle Reynolds numbers is also
examined
through a visualization experiment of an iron particle falling in a linear
shear flow of
a glycerin solution. On the other hand, the lift force on a rotating sphere
in a uniform
unsheared flow acts in the same direction independent of particle Reynolds
numbers.
Approximate expressions for the drag and lift coefficients for a rotating
sphere in a
linear shear flow are proposed over the wide range of
1[les ]Rep[les ]500.
Three-dimensional large-amplitude drop
oscillations: experiments and
theoretical analysis
Authors: AZUMA HISAO , YOSHIHARA SHOICHI 
Published: July 2002

Three-dimensional large-amplitude oscillations of a mercury drop were obtained by
electrical excitation in low gravity using a drop tower. Multi-lobed (from three to
six lobes) and polyhedral (including tetrahedral, hexahedral, octahedral and
dodecahedral) oscillations were obtained as well as axisymmetric oscillation patterns. The
relationship between the oscillation patterns and their frequencies was obtained, and
it was found that polyhedral oscillations are due to the nonlinear interaction of waves.A mathematical model of three-dimensional forced oscillations of a liquid drop is
proposed and compared with experimental results. The equations of drop motion are
derived by applying the variation principle to the Lagrangian of the drop motion,
assuming moderate deformation. The model takes the form of a nonlinear Mathieu
equation, which expresses the relationships between deformation amplitude and the
driving force's magnitude and frequency.
Three-dimensional effects in wind tunnel studies of shock wave reflection
Authors: SKEWS B. W. 
Published: July 2002

This paper concentrates on establishing the three-dimensional flow geometry
associated with studies of shock wave reflection between two symmetrical wedges in
supersonic flow. It considers the issue of hysteresis in such flows, and draws a distinction
between three different aspects of hysteresis, associated with: ideal two-dimensional
flow, flow with noise, and three-dimensional effects. The three-dimensional nature of
the flow field is elucidated by the use of oblique shadowgraph photography where
the optical axis of the shadowgraph system passes at an oblique angle, of as much as
55°, through the test section. The traces of the wave system reflecting off the tunnel
window are identified and are used to assist in identification of wave profiles. The
nature of the approach of the peripheral Mach reflections collapsing towards the
centre of the flow becomes evident, as does the mechanism of transition from Mach
reflection to regular reflection. Distinct evidence of the effects of flow perturbations
at the mechanical equilibrium transition point are presented, as are changes in the
rate of growth of the Mach stem near this point.It is shown that three-dimensional effects can have a major effect on the wedge
angle for transition. In the present tests, at Mach 3.1 and a wedge aspect ratio of
0.5, this occurs at a wedge angle of about 5° higher than the theoretical maximum
for the corresponding two-dimensional flow, where the dual solution domain extends
over only two degrees.
Rethinking the Chilean Party Systems
Authors: MONTES J. ESTEBAN , MAINWARING SCOTT , ORTEGA EUGENIO 
Published: July 2002

Although Chile is a relatively small country, writings about the Chilean
party systems have long been better and more voluminous than is the case
with most party systems in Latin America. Several orthodoxies have
emerged in this literature: that Chilean parties are strong, that the party
systems have been divided into three roughly equal parts, and that they
have been relatively stable. The purpose of this article is to challenge these
three orthodoxies. These orthodoxies are not completely wrong, but they
need to be qualified.The dominant view that Chilean parties are strong has been overstated.
They have been strong in some respects and for some periods, but not in
others. Parties have traditionally dominated mechanisms of representation
in Chile's democratic periods, overshadowing unions, social movements,
and other forms of representation. Party penetration in the electorate,
however, has not been powerful. Parties have appeared and disappeared
with frequency, and most parties have been relatively weak organisationally.
More so than is the case in Uruguay, Venezuela from 1958 until
the 1990s, Costa Rica or most of Western Europe, Chile's democratic
periods have allowed space for anti-party populists to develop successful
political careers, including capturing the presidency.
The impact of political liberalisation and democratisation on ethnic
conflict in Africa: an empirical test of common assumptions
Authors: Smith Zeric Kay 
Published: July 2002

This article provides an empirical test of a set of common theoretical
assumptions concerning the relationship between political liberalisation,
democratisation and ethnic conflict in Africa. The theory in question posits
that liberalisation will result in short-term increases in ethnic conflict and that
democratisation will be followed by a decrease in ethnic conflict. The article
employs a cross-national and time sensitive data set to test this hypothesis in
the context of contemporary sub-Saharan Africa. A compelling benefit of this
methodology is that it allows for an explanation of variation in ethnic conflict
both across states and over time.The results indicate that the relationship between political liberalisation and
ethnic conflict is the reverse of what the common assumptions would predict.
Liberalisation has had an inverse relationship to ethnic conflict in sub-Saharan Africa between 1988 and 1997. Democratisation does not have the
hypothesised effect even when lagged variables are employed. Structural
variables as represented by GDP per capita and infant mortality rates are
also systematically related to ethnic conflict. The author concludes that policy
makers and analysts should continue to pursue both liberalisation and
democratisation but should not neglect the central role of an adequate resource
base in reducing ethnic conflict in Africa. Political liberalisation and
democratic institutions, while providing some measure of relief, are by no
means silver bullets for the difficult challenges posed by ethnic conflict in
Africa.
Altered dopamine function in pathological gambling
Authors: BERGH C. , EKLUND T. , SÖDERSTEN P. , NORDIN C. 
Published: July 2002

Background. The possibility that monoaminergic
neurotransmission is altered in pathological gambling was examined.Methods. Monoamines and their metabolites were measured in
CSF obtained at level L4–5 from ten pathological gamblers and
seven controls.Results. A decrease in dopamine and an increase in
3,4-dihydroxyphenylacetic acid and homovanilic acid was found.
Noradrenaline and its metabolite 3-methoxy-4-hydroxyphenylglycol was
also increased but 5-hydroxytryptamine and 5-hydroxyindoleacetic acid
were unchanged.Conclusion. It is suggested that the function of the
dopaminergic system, possibly mediating positive and negative reward,
and the noradrenergic system, possibly mediating selective attention,
is changed in pathological gambling.
Migrant suicide rates in Australia and in country of birth
Authors: BURVILL P. W. 
Published: July 2002

Background. Various studies from Australia, Canada and the

United States have shown significant

rank correlations between the suicide rates of immigrants and those of

their country of birth (COB).

This study compares the rank ordering of age standardized suicide

rates of immigrants in Australia

for two periods, 1961–70 and 1979–90: (a) between

each period; and (b) with their COB for each period.Methods. Data were obtained from the World Health Organization

Annual Statistics and from the

Australian Bureau of Statistics. Comparisons were made for 11 countries

from England and Wales,

Ireland and Europe, for which there was a sufficiently large number

of immigrant suicides to warrant statistical analysis.Results. The data showed considerable heterogeneity in rates

of immigrants from various countries,

with increased rates in Australia compared with their COB. There were

consistently significant

Spearman rank correlations between the rates after immigration and

those in their COB for each

period, and between rates in the two periods for both immigrants and

for their COB, despite

increases in suicide rates, and considerable socio-economic demographic

changes between the various countries over that time span.Conclusions. The findings are used to argue two conclusions:

(i) the important influence of pre-migrant social and

cultural experiences in subsequent suicide rates in immigrants in their
host

country; and (ii) to support the case for the reliability of

using international suicide data for comparative epidemiological research.
Smooth pursuit and saccadic abnormalities in first-episode schizophrenia
Authors: HUTTON S. B. , CRAWFORD T. J. , PURI B. K. , DUNCAN L.-J. , CHAPMAN M. , KENNARD C. , BARNES T. R. E. , JOYCE E. M. 
Published: July 2002

Background. Previous studies of oculomotor dysfunction
in
schizophrenia have tended to
concentrate on abnormalities of smooth pursuit eye tracking in chronic
medicated patients. We
report the results of a study of smooth pursuit, reflexive and
antisaccade performance in drug naive
and antipsychotic treated first-episode schizophrenic patients.Methods. Smooth pursuit and saccadic eye movements were recorded

in 36 first-episode
schizophrenic patients and 36 controls matched for age and estimated IQ.
The schizophrenic
patients were divided into drug-naive (N=17) and antipsychotic

treated groups (N=19).Results. Smooth pursuit velocity gain was significantly
lower than controls only in the drug-naive
patients. The treated patients did not differ significantly from
either the controls or the untreated
group. In an antisaccade paradigm both treated and drug-naive schizophrenic

patients demonstrated
an increased number of errors, but only drug-naive patients also demonstrated

an increased latency in initiating correct antisaccades.Conclusions. These impairments are unlikely to be due to a

generalized deficit in oculomotor
function in the schizophrenic groups, as there were no differences
between the groups in saccadic
metrics on a reflexive saccade task. The results show that both smooth
pursuit and saccadic
abnormalities are present at the onset of schizophrenia and are integral
to the disorder.
Abstracts of trials presented at the Vth World Congress of
Psychiatry (Mexico, 1971): a cohort study
Authors: DIEZEL K. , PHAROAH F. M. , ADAMS C. E. 
Published: July 2002

Background. Systematic reviews should identify all relevant
trials in order to minimize the potential
for bias and the play of chance in their results. Other specialities have
shown that conference
proceedings are a rich source of trials, but many of these trials are never
fully published.Methods. All clinical trials presented at a single conference
(Vth World Congress of Psychiatry,
Mexico, 1971) were identified by hand searching. Full publications of these
abstracts were then
sought on five databases by searching for the authors or relevant key words.Results. Full publications were found for 46% of the abstracts.
The odds of publication decreased
for abstracts that were from a non-Anglophone country or that failed to
mention randomization.Conclusions. Anyone wishing to undertake a systematic review
of a mental-health care topic should
search relevant conference proceedings for trials.
A comparison of the utility of dimensional and
categorical representations of psychosis
Authors: VAN OS J. , GILVARRY C. , BALE R. , VAN HORN E. , TATTAN T. , WHITE I. , MURRAY ON BEHALF OF THE UK700 GROUP R. 
Published: July 2002

Background. The usefulness of any diagnostic scheme is directly related to its ability to provide
clinically useful information on need for care. In this study, the clinical usefulness of dimensional
and categorical representations of psychotic psychopathology were compared.Method. A total of 706 patients aged 16–65 years with chronic psychosis were recruited.
Psychopathology was measured with the Comprehensive Psychopathological Rating Scale (CPRS).
Lifetime RDC, DSM-III-R, and ICD-10 diagnoses and ratings of lifetime psychopathology were
made using OPCRIT. Other clinical measures included: (i) need for care; (ii) quality of life; (iii)
social disability; (iv) satisfaction with services; (v) abnormal movements; (vi) brief
neuropsychological screen; and (vii) over the last 2 years – illness course, symptom severity, employment,
medication use, self-harm, time in hospital and living independently.Results. Principal component factor analysis of the 65 CPRS items on cross-sectional
psychopathology yielded four dimensions of positive, negative, depressive and manic symptoms.
Regression models comparing the relative contributions of dimensional and categorical
representations of psychopathology with clinical measures consistently indicated strong and significant
effects of psychopathological dimensions over and above any effect of their categorical counterparts,
whereas the reverse did not hold. The effect of psychopathological dimensions was mostly
cumulative: high ratings on more than one dimension increased the contribution to the clinical
measures in a dose-response fashion. Similar results were obtained with psychopathological
dimensions derived from lifetime psychopathology ratings using the OCCPI.Conclusions. A dimensional approach towards classification of psychotic illness offers important
clinical advantages.
Does old age reduce the risk of anxiety and depression? A review of
epidemiological studies across the adult life span
Authors: JORM A. F. 
Published: July 2002

Background. There is considerable disagreement about what happens to the risk of anxiety and
depression disorders and symptoms as people get older.Methods. A search was made for studies that examine the occurrence of anxiety, depression or
general distress across the adult life span. To be included, a study had to involve a general
population sample ranging in age from at least the 30s to 65 and over and use the same assessment
method at each age.Results. There was no consistent pattern across studies for age differences in the occurrence of
anxiety, depression or distress. The most common trend found was for an initial rise across age
groups, followed by a drop. Two major factors producing this variability in results were age biases
in assessment of anxiety and depression and the masking effect of other risk factors that vary with
age. When other risk factors were statistically controlled, a more consistent pattern emerged, with
most studies finding a decrease in anxiety, depression and distress across age groups. This decrease
cannot be accounted for by exclusion of elderly people in institutional care from epidemiological
surveys or by selective mortality of people with anxiety or depression.Conclusion. There is some evidence that ageing is associated with an intrinsic reduction in
susceptibility to anxiety and depression. However, longitudinal studies covering the adult life span
are needed to distinguish ageing from cohort effects. More attention needs to be given to
understanding the mechanism behind any ageing-related reduction in risk for anxiety and
depression with age. Possible factors are decreased emotional responsiveness with age, increased
emotional control and psychological immunization to stressful experiences.
Does depression predict cognitive outcome 9 to 12 years later? Evidence from a prospective study of elderly hypertensives
Authors: CERVILLA J. A. , PRINCE M. , JOELS S. , MANN A. 
Published: July 2002

Background. Previous longitudinal studies of the association between depression
and cognitive dysfunction have had relatively short follow-up periods. This
report presents a long-term study of the association between baseline syndromal
depression and cognitive outcome measured 9 to 12 years later.Methods. Self-CARE (D) depression, cognitive function and pre-morbid intelligence
were recorded on 1083 subjects on entry to the Medical Research Council trial of
treatment of hypertension in older adults in 1983–5. In 1994–5, we aimed to
re-interview all survivors to assess cognitive function using the MMSE. We used
multivariate analysis to explore whether baseline depression predicted cognitive outcome
after this long follow-up period.Results. Baseline depression was crudely associated with poorer cognitive outcome
at time 2. However, this long-term prospective association was no longer apparent
after adjusting for baseline cognitive performance, which was associated with baseline
depression and robustly predicted cognitive outcome at time 2. We found that gender
modified the association between depression and poorer cognitive outcome, so that
the association was statistically significant only among men.Conclusion. Propensity for depression and failing cognition may have common
determinants that still need to be established by future neurobiological
investigations in conjunction with further long-term prospective epidemiological
research.