bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluidization by lift of 300 circular particles in plane Poiseuille flow by direct numerical simulation
Authors: CHOI HYOUNG G. , JOSEPH DANIEL D. 
Published: July 2002

We study the transport of a slurry of heavier-than-liquid circular particles in a plane
pressure-driven flow in a direct simulation. The flow is calculated in a periodic domain
containing 300 circular particles. The study leads to the concept of fluidization by lift
in which all the particles are suspended by lift forces against gravity perpendicular to
the flow. The study is framed as an initial-value problem in which a closely packed
cubic array of particles resting on the bottom of the channel is lifted into suspension.
All the details of the flow are resolved numerically without model assumptions. The
fluidization of circular particles first involves bed inflation in which liquid is driven
into the bed by high pressure at the front and low pressure at the back of each circle
in the top row. This kind of bed inflation occurs even at very low Reynolds numbers
but it takes more time for the bed to inflate as the Reynolds number is reduced.
It appears that the bed will not inflate if the shear Reynolds number is below the
critical value for single particle lift-off. The flows with a single particle are completely
determined by a shear Reynolds number and a gravity parameter when the density
ratio and aspect ratio parameters are specified. In the multi-particle case, the volume
fraction and distribution also matters. The transition to a fully fluidized slurry by
waves is discussed.An analytical model of the steady motion of a single particle dragged forward in
a Poiseuille flow is derived and compared with a simulation. The undisturbed fluid
velocity is always larger than the particle velocity, producing a fluid hold-up. The
effect of the hold-up in the many particle case is to greatly reduce the velocity of
the mixture which may be described by a two-fluid model in which the solid laden
mixture is regarded as a second fluid with effective properties.
Global capillary instability of an inclined jet
Authors: YAKUBENKO P. A. 
Published: July 2002

The primary goal of the paper is to demonstrate that a circular
jet

of inviscid liquid,

which issues from a nozzle at an angle to the gravitational field, can

sustain a self-excited linear global mode. The mode is found for the

flow that is locally convectively

unstable at every point, i.e. has no region of local absolute instability.
A simple

experiment shows that the mode can evolve into a wave of finite amplitude,
which is

localized in space near the nozzle.Section 2 of the paper summarizes some recent developments in the linear
theory

of stability of weakly inhomogeneous flows.
Instabilities and bifurcation of non-equilibrium
two-phase flows
Authors: ADAM STEPHAN , SCHNERR GÜNTER H. 
Published: July 2002

New instabilites of unsteady transonic flows
with non-equilibrium phase transition
are presented including unsymmetric flow patterns with moving oblique shock
systems in supersonic nozzles with perfectly symmetric shapes. The phenomena
were
first detected when performing experiments in our supersonic wind tunnel
with
atmospheric supply and could be perfectly reproduced by numerical simulations
based
on the Euler equations, i.e. neglecting the viscosity of the fluid. The
formation of
the liquid phase is modelled using the classical nucleation theory for
the steady state together with the Hertz–Knudsen droplet growth law
and
yields qualitatively and
quantitatively excellent agreement with experiments in the unsteady flow
regime with
high-frequency oscillations including the unstable transient change of
the structure
from symmetric to unsymmetric flow.For engineering applications the sudden increase or decrease of the
frequency by
a factor 2 or more and of the pressure amplitude at the bifurcation limits
is of
immediate practical interest, e.g. for flutter excitation of turbomachinery
blading.
Solute transport in divergent radial flow through
heterogeneous porous media
Authors: INDELMAN PETER , DAGAN GEDEON 
Published: July 2002

Radial flow takes place in a heterogeneous porous formation of
random and stationary
log-conductivity Y(x), characterized by the mean
〈Y〉, the variance σ2Y
and the two-
point autocorrelation ρY which in turn has
finite and different horizontal and vertical
integral scales, I and Iv,
respectively. The steady flow is driven by a head difference
between a fully penetrating well and an outer boundary, the mean velocity
U being
radial. A tracer is injected for a short time through the well envelope
and the thin
plume spreads due to advection by the random velocity field and to pore-scale

dispersion. Transport is characterized by the mean front
r=R(t) and by the second
spatial moment of the plume Srr. Under ergodic

conditions, i.e. for a well length much
larger than the vertical integral scale, Srr

is equal to the radial fluid trajectory variance
Xrr.The aim of the study is to determine Xrr(t)

for a given heterogeneous structure
and for given pore-scale dispersivities. The problem is more complex than
the similar
one for mean uniform flow. To simplify it, the well is replaced by a line
source, the
domain is assumed to be infinite and a first-order approximation in
σ2Y is adopted. The
solution is still difficult, being expressed with the aid of a few quadratures.
It is found,
however, that it can be derived quite accurately for a sufficiently small
anisotropy
ratio e=Iv/I by
retaining only one term of the velocity two-point covariance. This
major simplification leads to simple calculations and even to analytical
solutions in
the absence of pore-scale dispersion.To compare the results with those prevailing in homogeneous media, apparent
and
equivalent macrodispersivities are defined for convenience.The major difference between transport in radial and uniform flow is
that the
asymptotic, large-time, apparent macrodispersivity in the former is smaller
by a
factor of 3 than in the latter. For a three-dimensional point source the
reduction is by
a factor of 5. This effect is explained by the rapid change of the mean
velocity during
the period in which the velocities of two particles injected at the source
become
uncorrelated.In contrast, the equivalent macrodispersivity tends to its value in
uniform flow far
from the well, where the flow is slowly varying in space.
A kinematic model of a ducted flame
Authors: DOWLING A. P. 
Published: July 2002

A premixed ducted flame, burning in the wake of a bluff-body flame-holder, is
considered. For such a flame, interaction between acoustic waves and unsteady
combustion can lead to self-excited oscillations. The concept of a time-invariant
turbulent flame speed is used to develop a kinematic model of the response of the flame
to flow disturbances. Variations in the oncoming flow velocity at the flame-holder
drive perturbations in the flame initiation surface and hence in the instantaneous rate
of heat release. For linear fluctuations, the transfer function between heat release and
velocity can be determined analytically from the model and is in good agreement
with experiment across a wide frequency range. For nonlinear fluctuations, the model
reproduces the flame surface distortions seen in schlieren films.Coupling this kinematic flame model with an analysis of the acoustic waves generated
in the duct by the unsteady combustion enables the time evolution of disturbances
to be calculated. Self-excited oscillations occur above a critical fuel–air ratio.
The frequency and amplitude of the resulting limit cycles are in satisfactory agreement
with experiment. Flow reversal is predicted to occur during part of the limit-cycle
oscillation and the flame then moves upstream of the flame-holder, just as in experimental
visualizations. The main nonlinearity is identified in the rate of heat release,
which essentially ‘saturates’ once the amplitude of the velocity fluctuation exceeds
its mean. We show that, for this type of nonlinearity, describing function analysis can
be used to give a good estimate of the limit-cycle frequency and amplitude from a
quasi-nonlinear theory.
Natural course of symptoms in Cambodia veterans: a follow-up study
Authors: DE VRIES M. , SOETEKOUW P. M. M. B. , VAN DER MEER J. W. M. , BLEIJENBERG G. 
Published: July 2002

Background. Dutch (ex-)servicemen were deployed in the 1992–3-peace operation UNTAC in
Cambodia. Since their return, they have voiced concerns about the health consequences of their
service and they have reported symptoms such as fatigue and cognitive problems. The natural
course of symptoms in Dutch Cambodia veterans was evaluated in a prospective study.Methods. At 18-months follow-up, a questionnaire was sent to 354 veterans who met a set case
definition for symptoms in Cambodia veterans or who had sub-threshold scores. Initial
measurement of fatigue severity, psychological well-being, depression, post-traumatic stress
disorder, trait-anxiety, self-efficacy and causal attributions, was used to evaluate predictors for self-reported improvement and low levels of fatigue at follow-up.Results. At follow-up, 19% of the respondents reported complete recovery, 20% felt much better,
57% had the same complaints and 4% had become worse compared with their initial assessment.
Self-reported improvement and less severe fatigue at follow-up were predicted by less severe fatigue
at initial assessment and more perceived control over symptoms.Conclusions. Self-reported improvement was reported in a considerable percentage of Cambodia
veterans, whereas another substantial percentage of Cambodia veterans continued to suffer with
severe levels of fatigue and related symptoms. Predictors of improvement in Cambodia veterans and
patients with chronic fatigue syndrome show similarities and also seem to bear importance for Gulf
War veterans.
Recreational use of 3,4-methylenedioxymethamphetamine (MDMA) or ‘ecstasy’: evidence for cognitive impairment
Authors: BHATTACHARY SARAJANE , H. POWELL JANE 
Published: July 2002

Background. It has recently been shown that 3,4-methylenedioxymethamphetamine (MDMA) or ‘ecstasy’ causes long-lasting alterations to brain structure and function in animals, and there is mounting evidence that recreational users of the drug show impairments in some aspects of cognitive functioning including memory for verbal information. The present study investigates possible effects on other cognitive functions and explores the temporal course of development and resolution of these impairments by comparing novice, regular and abstaining users with a matched group of non-users.Methods. Eighty participants categorized as non-users, novice users, regular users or currently abstinent users of MDMA were assessed on tests of verbal IQ, reversed digit span, immediate and delayed recall of a prose passage and of a complex geometric figure and verbal fluency.Results. The four groups were well-matched for verbal IQ and on demographic variables. They differed in frequency of cannabis use over the last month, but this did not correlate with any cognitive test scores. All three groups of MDMA users showed significantly poorer verbal fluency and immediate and delayed prose recall than non-users. Days since last use and total lifetime consumption of MDMA made separate contributions to the variance in recall scores, accounting jointly for almost half of the variance in delayed recall. By contrast, the groups did not differ on either visual recall or reversed digit span.Conclusions. The observed deficits provide further evidence of impairments of verbal but not visual memory in MDMA users, and indicate that the deficits are not attributable either to differences in general reasoning ability or to impairment of working memory. The data further suggest that the observed impairments may be attributable to a combination of reversible acute effects of MDMA resolving over a period of 2–3 weeks and more long-term changes associated with extent of lifetime consumption.
Increased plasma concentrations of the 5-HT precursor amino acid
tryptophan and other large neutral amino acids in violent
criminals
Authors: ERIKSSON T. , LIDBERG L. 
Published: July 2002

Background. Aggression has been suggested to be
related to abnormal brain 5-HT activity. This amine is synthesized in
brain from tryptophan, which is transported through the
blood–brain barrier in competition with other amino acids. The
relationship between tryptophan and its endogenous amino acid
competitors in plasma might thus influence the availability of
tryptophan in the brain and consequently brain 5-HT activity.Methods. Plasma amino acids were determined in 89
offenders who had committed various violent and non-violent crimes and
in 14 healthy controls.Results. Both tryptophan and its competitors were higher
in offenders who had committed violent crimes compared both with
non-violent offenders and with controls. No difference was, however,
seen in the relationship between tryptophan and its competitors.Conclusions. The results support the contention that
violent behaviour is related to biochemical deviations but could not
explain a possible decreased brain 5-HT activity.
Mechanisms underlying memory impairment in schizophrenia
Authors: BRÉBION G. , AMADOR X. , SMITH M. J. , GORMAN J. M. 
Published: July 2002

Background. The purpose of this experiment was to
investigate mechanisms underlying commonly-observed verbal memory
impairments in schizophrenia, and especially the hypothesized encoding
deficit.Methods. A verbal memory task was administered to 38
patients with schizophrenia and 38 normal controls. Three functions
involved in long-term memory – encoding, early phase of storage,
retrieval – were investigated. First, non-organizable lists were
compared to semantically-organizable lists in a free recall task, in
order to vary encoding conditions. Superficial encoding (measured by a
‘sequence’ index) and deep encoding (measured by a
categorization index) were assessed. Secondly, early storage was
investigated by varying the delay between learning and recall. Lastly,
cues were provided for organizable lists (semantic cues) and
non-organizable lists (recognition sheet), in order to vary retrieval
conditions.Results. An analysis of variance revealed an interaction
between type of list (organizable, non-organizable) and group, showing
that patients used organization less than controls. A further analysis
showed that deep encoding was impaired. Also, although the propensity
to use superficial encoding was unimpaired, its efficiency was less.
The analysis of variance revealed no interaction with delay or with
either type of cue. A correlation was found between deep processing
and memory performance in both groups.Conclusions. A major deficit in encoding appeared in the
patient group, with a lesser use of deep encoding and a lesser
efficiency of superficial encoding. On the other hand, the early phase
of storage and the retrieval function seemed unaffected. Overall
memory performance appeared to be related to the depth of
encoding.
Sibling pairs with schizophrenia or schizoaffective
disorder: associations of subtypes, symptoms and
demographic variables
Authors: CARDNO A. G. , JONES L. A. , MURPHY K. C. , SANDERS R. D. , ASHERSON P. , OWEN M. J. , McGUFFIN P. 
Published: July 2002

Background. Affected sibling pairs provide a valuable

means of investigating the familial basis of
clinical heterogeneity in schizophrenia.Methods. Associations of schizophrenia subtypes, psychotic

symptoms (defined by SAPS/SANS
and OPCRIT), affective episodes and demographic variables were studied

in 109 sibling pairs with
DSM-IV schizophrenia or schizoaffective disorder.Results. None of the subtypes or affective episodes were
significantly associated within pairs. A
broad definition of positive formal thought disorder, grandiose
delusions and delusions of influence
(all from OPCRIT) were modestly associated. There was no excess of same-sex
pairs. There were
modest associations for age of illness onset, pre-morbid adjustment
and illness severity. Caution is
required in interpreting the results because many statistical tests were
carried out.Conclusions. None of the variables appears to be closely
associated with specific genetic or shared
environmental factors that contribute liability to schizophrenia. They
are at best only weakly
associated with such factors, and/or are associated with factors unrelated
to the aetiology of
schizophrenia.
Neuropsychological assessment of young people at
high genetic risk for developing schizophrenia
compared with controls: preliminary findings of the
Edinburgh High Risk Study (EHRS)
Authors: BYRNE M. , HODGES A. , GRANT E. , OWENS D. C. , JOHNSTONE E. C. 
Published: July 2002

Background. Finding risk indicators for schizophrenia among groups of individuals at high genetic
risk for the disorder, has been the driving force of the high risk paradigm. The current study
describes the preliminary results of a neuropsychological assessment battery conducted on the first
50% of subjects from the Edinburgh High Risk Study.Methods. One hundred and four high risk subjects and 33 normal controls, age and sex matched,
were given a neuropsychological assessment battery. The areas of function assessed and reported
here include intellectual function, executive function, perceptual motor speed, mental control/encoding,
verbal ability and language, learning and memory measures, and handedness.Results. The high risk subjects performed significantly more poorly than the control subjects in the
following domains of neuropsychological function: intellectual function, executive function, mental
control/encoding and learning, and memory. Controlling for IQ, high risk subjects made
significantly more errors on the Hayling Sentence Completion Test (HSCT), took longer to complete
section A of the HSCT, had lower scores on the delayed recall condition of the visual reproductions
subtest of the Wechsler Memory Scale-Revised, and had significantly poorer Rivermead
Behavioural Memory Test (RBMT) standardized scores. The presence of significant group by IQ
interactions for the RBMT and time to complete section A of the HSCT suggested that differences
among the groups were more marked in the lower IQ range. Performance on the HSCT was found
to be related to the degree of family history of schizophrenia.Conclusions. High risk subjects performed more poorly than controls on all tests of intellectual
function and on aspects of executive function and memory.
POLITICS, PUBLIC FINANCE AND THE BRITISH–IRISH ACT OF UNION OF 1801
Authors: McCavery Trevor 
Published: July 2002

AbstractBEFORE the smoke of the Irish rebellion of 1798 had cleared, the British prime minister William Pitt was convinced of the necessity of a legislative union between Britain and Ireland. He broached the subject seriously with his cabinet colleague, Lord Grenville, on 2 June and by 4 June the joint post master general, Lord Auckland, an expert on Irish commercial affairs, was brought into Pitt's confidence. Pitt told Auckland that he and Grenville had been able to: ‘see daylight in almost everything but what relates to trade and revenue.' The subject of this paper is to discover how matters of trade and revenue were arranged in the Act of Union and to discuss some of the political difficulties which arose from implementing these arrangements. As the evolution of ministers' thinking is documented, the authorship of some points can be precisely identified and the thinking and tacit economic forecasting brought to light. This paper will suggest that the arrangements were intended to be generous to Ireland and contrasts with an Irish nationalist interpretation of the subject articulated in the early decades of the twentieth century. Then the difficulties that politicians experienced in executing policies within the framework laid down by these articles are considered. The whole vice-regal system of government was by no means guaranteed in the immediate post-Union period as it worked against the chancellor of the Irish exchequer in his attempts to manage Irish public finance.
RECONSIDERING THE IRISH ACT OF UNION
Authors: Connolly S.J. 
Published: July 2002

AbstractTHE political, administrative and social consequences of the union of Great Britain and Ireland, and even more the eventual unravelling of the structures it created, have for the greater part of the past century provided Irish historians with a major theme. By contrast the measure itself has received little sustained analysis or discussion. F.R. Bolton's monograph, first published in 1966, remains – more than three decades later – the standard reference. In part this is a tribute to the depth, breadth and penetration of Bolton's account. But there is also at least the suggestion that the negotiation and passage of the union legislation, during 1799–1800, is to be seen as unproblematic, a relatively straightforward event providing a terminus or a starting point for discussion of the more complex and challenging periods on either side.
How and why the brain makes dreams: A report card on current research on dreaming
Authors: Cartwright Rosalind 
Published: July 2002

The target articles in this volume address the three major questions about dreaming that have been most responsible for the delay in progress in this field over the past 25 years. These are: (1) Where in the brain is dreaming produced, given that dream reports can be elicited from sleep stages other than REM? (2) Do dream plots have any intrinsic meaning? (3) Does dreaming serve some specialized function? The answers offered here when added together support a new model of dreaming that is testable, and should revitalize this area of study.[Hobson et al.; Nielsen; Revonsuo; Solms; Vertes & Eastman]
Forum: Transforming political community: a response to the critics
Authors: LINKLATER ANDREW 
Published: July 2002

My first task is to thank the editors for creating a forum in which four authors from very different branches of social and political theory discuss my recent book on the transformation of political community. I am no less indebted to the authors involved for their participation in this debate. I hope this short reply does justice to their insightful comments and searching criticisms.Randall L. Schweller is most sharply at odds with my position and I begin by responding to his criticisms. I then turn to the comments made by R. B. J. Walker and Jean Bethke Elshtain who subscribe to the critical project, broadly conceived, though not to my version of it. This essay ends with some responses to Norman Geras who shares my commitment to building on the Kantian and Marxian tradition but who has a rather different method of taking it further.
Causes of disease and causes of death
Authors: CARTER K. CODELL 
Published: July 2002

In early-nineteenth-century medical literature, one finds an elegant symmetry between causes of disease and causes of death: both were sufficient causes of particular events. However, as I will argue, by the end of the century physicians no longer sought sufficient causes of individual disease episodes – instead almost all of medical research was organized around the quest for necessary causes that were shared by all the episodes of each particular disease. Such causes carried great practical and theoretical advantages: they enabled physicians to control and to explain disease phenomena.One might wonder why there has been no parallel change in our thinking about causes of death; to this very day, causes
of death are sufficient causes of particular events. In principle there is no apparent reason why we could not identify necessary causes for classes of deaths – indeed, we sometimes do so. But, in the case of death, such causes hold little interest. Because of how they are used, sufficient causes for individual deaths are more interesting and more important to us than are necessary causes of deaths. Thus, the change in thinking about causes of disease – the change that destroyed the symmetry between causes of disease and causes of death – may not reflect simply progress within a fixed system of medical goals and values, but a profound change in the social role of physicians.