bluuebunny/crossref_metadata_2025 huggingface dataset:
On the acoustic levitation of droplets
Authors: YARIN A. L. , PFAFFENLEHNER M. , TROPEA C.
Published: July 2002

This paper deals with the theoretical and experimental

investigation of acoustically

levitated droplets. A method of calculation of the acoustic

radiation pressure based on

the boundary element method (BEM) is presented. It is

applied to predict shapes of

droplets levitated in an acoustic field (and as a result,

deformed by it). The method was

compared with several known exact and approximate analytical

results for rigid

spheres and shown to be accurate (and a widely used

approximate formula for the

acoustic levitation force acting on a rigid sphere was

found to be inaccurate for sound

wavelengths comparable with the sphere radius). The method

was also compared with

some other theoretical approaches known from the literature.

Displacement of the droplet centre relative to the pressure

node is accounted for and

shown to be significant. The results for droplet shapes and

displacements are compared

with experimental data, and the agreement is found to be

rather good. Furthermore,

the experimental investigations reveal a unique relationship

between the aspect ratio of

an oblate droplet and the sound pressure level in the

levitator. This relationship agrees

well with the predicted shapes. A practical link between

droplet shape or droplet

displacement and sound pressure level in a levitator is

therefore now available.
On gravity-wave scattering by non-secular changes in depth
Authors: MILES JOHN
Published: July 2002

The reflection of a straight-crested gravity wave by
a non-secular perturbation h1(x) in
depth relative to an otherwise flat bottom of depth h0

is calculated through an
expansion in ε∝h1/h0.

Explicit results are developed up to second order for the sinusoidal patch

h1=−bsin(mπx/l),

0<x<l, and reduced for Bragg resonance.
Trapped modes are absent at first order but appear at second order and
contribute
O(ε2)/O(ε3)
to the maximum (Bragg-resonant) reflection coefficient for odd/even
m. A
third-order approximation that includes the dominant contributions of the
third-order
components of the resonant peak of the reflection coefficient for large
m, but neglects
the trapped modes, predicts resonant peaks that agree with the values measured
by
Davies & Heathershaw (1984).
On reduction of turbulent wall friction through
spanwise wall oscillations
Authors: DHANAK M. R. , SI C.
Published: July 2002

A model for turbulent skin friction, proposed by Orlandi &
Jimenez, involving
consideration of quasi-streamwise vortices in the cross-stream plane, is
used to study
the effect on the skin friction of oscillating the surface beneath the
boundary layer
in the spanwise direction. Using an exact solution of the Navier–Stokes
equations, it
is shown that the interaction between evolving, axially stretched, streamwise
vortices
and a modified Stokes layer on the oscillating surface beneath, leads to
reduction in
the skin friction, the Reynolds stress and the rate of production of kinetic
energy,
consistent with predictions based on experiments and direct numerical simulations.
Instabilities of conical flows causing steady bifurcations
Authors: SHTERN VLADIMIR , HUSSAIN FAZLE
Published: July 2002

A new stability approach is developed for a wide class of strongly
non-parallel
axisymmetric flows of a viscous incompressible fluid. This approach encompasses
all
conical flows, and all steady and weakly unsteady disturbances, while prior
studies
were limited to specific flows and particular disturbances. A specially
derived form of
the Navier–Stokes equations allows the exact reduction of the linear
stability problem
to a system of ordinary differential equations. We found that disturbances
originating
at the boundaries of a similarity region cause a variety of steady bifurcations.

Consideration of the still fluid allows disturbances to be classified into
inner, outer and
global modes, depending on the boundary conditions perturbed. Then we identify
and
study modes which cause bifurcation as the Reynolds number increases. The
study
provides improved understanding of (a) azimuthal symmetry
breaking, (b) genesis of swirl, (c) onset of heat convection,

(d) hydromagnetic dynamo, (e) hysteretic
transitions, and (f) jump flow separation. We also discover and
analyse two new
bifurcations: (g) fold catastrophes and (h)
appearance of radial oscillations in swirl-free
jets. The stability analysis reveals that bifurcations (a),
(c) and (f) are caused by inner
perturbations, bifurcations (b), (d), (e) and

(g) by outer perturbations, and bifurcation
(h) by global perturbations. We deduce amplitude equations to
describe the nonlinear
spatiotemporal development of disturbances near the critical Reynolds numbers
for (b)
and (g). Disturbances switching between the basic and secondary
steady states are
found to grow monotonically with time.
Experiments with constrained chimney-plume
flows in the system ammonium chloride–water:
comparison with the unconstrained case
Authors: LIU SHAN , HELLAWELL ANGUS
Published: July 2002

Thermo-solutal chimney-plume flows from a solidifying dendritic mushy region have
been promoted in thin-walled glass tubes of internal radii from 0.3 mm–2.0 mm.
Flow rates, liquid compositions and temperatures were measured as functions of
the depth of immersion of capillary tubes in the advancing mushy region. The
results demonstrate competition between buoyancy pressures and the restrictions of
liquid recirculation within the dendritic array and have been analysed to provide
permeability data for the mushy region at high liquid fractions. These data have been
used to make some assessments of channel/plume dimensions for naturally occurring,
unconstrained flows in the same system.
Miscible porous media displacements in
the quarter five-spot configuration. Part 3. Non-monotonic viscosity profiles
Authors: PANKIEWITZ CHRISTIAN , MEIBURG ECKART
Published: July 2002

The influence of a non-monotonic viscosity–concentration relationship on miscible
displacements in porous media is studied for radial source flows and the quarter five-spot configuration. Based on linear stability results, a parametric study is presented
that demonstrates the dependence of the dispersion relations on both the Péclet
number and the parameters of the viscosity profile. The stability analysis suggests
that any displacement can become unstable provided only that the Péclet number
is sufficiently high. In contrast to rectilinear flows, for a given end-point viscosity
ratio an increase of the maximum viscosity generally has a destabilizing effect on the
flow. The physical mechanisms behind this behaviour are examined by inspecting the
eigensolutions to the linear stability problem. Nonlinear simulations of quarter five-spot displacements, which for small times correspond to radial source flows, confirm
the linear stability results. Surprisingly, displacements characterized by the largest
instability growth rates, and consequently by vigorous viscous fingering, lead to the
highest breakthrough recoveries, which can even exceed that of a unit mobility ratio
flow. It can be concluded that, for non-monotonic viscosity profiles, the interaction
of viscous fingers with the base-flow vorticity can result in improved recovery rates.
Singularity formation in the strongly nonlinear
wide-vortex/Tollmien–Schlichting-wave
interaction equations
Authors: WALTON ANDREW G. , PATEL RUPA A.
Published: July 2002

A combined numerical/analytical study of the wide-vortex/wave interaction equations,
describing boundary-layer instability, is presented. Depending on the obliqueness β
of the wave input, different solution properties are obtained. For β = 1, oscillations
in the wave amplitude lead to the evolution of a strongly three-dimensional
mean flow, while for β = 2 the interaction is characterized by the development of a
singularity in the wave pressure amplitude. This latter behaviour is modelled using
an approximate form for the mean flow skin friction and the resulting amplitude
equation is analysed using a combination of numerical and asymptotic techniques.
A simple method is described for determining the singularity location for a given
spanwise wavenumber, and the asymptotic behaviour of the pressure amplitude as
the singularity is approached is deduced.
Rayleigh–Marangoni oscillatory instability in a
horizontal liquid layer heated from above: coupling and mode mixing of internal and
surface dilational waves
Authors: REDNIKOV A. YE. , COLINET P. , VELARDE M. G. , LEGROS J. C.
Published: July 2002

An oscillatory instability mechanism is identified for a horizontal liquid layer with
undeformable open surface heated from the air side. Although buoyancy and surface
tension gradients are expected to play a stabilizing role in this situation, we show that,
acting together, they may lead to the instability of the motionless state of the system.
The instability is a consequence of the coupling between internal and surface waves,
whose resonant interaction and resulting mode mixing are discussed. Predictions
amenable to experimental test are given together with a thorough analytical and
numerical study of the problem.
Deformation and breakup of Newtonian and non-Newtonian conducting drops
in an electric field
Authors: HA JONG-WOOK , YANG SEUNG-MAN
Published: July 2002

In this article, we considered experimentally the deformation and breakup of
Newtonian and non-Newtonian conducting drops in surrounding fluid subjected to a
uniform electric field. First, we examined three distinctive cases of Newtonian-fluid
pairs with different relative conductivities, namely highly conducting drops, conducting
drops and slightly conducting drops. The results on the Newtonian fluids
demonstrated that when the conductivity of the drop is very large relative to that
of the surrounding fluid, the deformation response of such highly conducting drops
is described well by the electrohydrostatic theory, especially with regard to the prediction
of the critical point. Specifically, when the ratio of drop to continuous-phase resistivity,
R, was less than 10−5, the electrohydrostatic theory was quite
satisfactory. Then, the non-Newtonian effect on the drop deformation and breakup was studied for highly
conducting drops which satisfied the condition R < O(10−5).
The highly conducting drop became stable in a weak or moderate field strength when either the
drop or the continuous phase was non-Newtonian. On the other hand, when both the
phases were non-Newtonian, more complicated responses were observed depending
on the ratio of zero-shear-rate viscosities. Although the effects of the rheological
properties are minimal on all features away from the critical conditions for breakup
or prior to the instability, the non-Newtonian properties have a significant influence
during drop burst, which is accompanied by large velocities and velocity gradients.
In particular, when the ratio of the zero-shear-rate viscosity of the drop to that of
the ambient fluid was much larger than unity, non-Newtonian properties of the drop
phase enhanced the drop stability. Conversely, the elasticity of the continuous phase
deteriorated the drop stability. Meanwhile if the zero-shear-rate viscosity ratio was
much smaller than unity, the elasticity of the continuous phase produced a stabilizing
effect. The effects of resistivity and viscosity ratios on the breakup modes were also
investigated. When at least one of the two contiguous phases possessed considerable
non-Newtonian properties, tip streaming appeared.
The massacre of refugees in Congo: a case of UN
peacekeeping failure and international law
Authors: Emizet Kisangani N. F.
Published: July 2002

The massacre of refugees during the 1996–7 war in Congo illustrates the gap
between existing legal standards and their application, as the principle of
sovereignty rationalises states' behaviour against helpless people. This paper
assesses available information on the scale of the massacre, concluding that
about 232,000 refugees were killed. It argues that firmness in demanding
justice and protecting human rights does not require ignoring the objectives
of stability and prosperity for any country, but rather that it is the best way
of promoting those goals and strengthening state sovereignty within the international
community. To implement international law related to refugees
will require making states and non-state players responsible for their actions
to the international community, since any outflow of refugees creates negative
externalities or costs that are unequally borne by this community.
Third-order contributions to ion-acoustic solitons in a plasma with two types of cold
positive ions and two-temperature non-isothermal electrons
Authors: MAJUMDAR S. R. , PAUL S. N. , DAS K. P.
Published: July 2002

Higher-order nonlinear and dispersive effects on ion-acoustic solitons in
a plasma consisting of two types of cold positive ions and two-temperature non-isothermal
electrons are studied using a reductive perturbation method. An integrated
form of the basic sets of fluid equations consisting of two types of positive
ions and two types of non-isothermal electrons is derived in terms of a pseudo-potential.
A perturbation solution of this equation is obtained by the Bogoliubov–Mitropolsky method.
At the lowest order, we obtain a modified Korteweg–de Vries
solitary-wave solution, which has a sech4 profile. Calculations are carried out at
the next two higher orders. The secularity-removing condition at each order gives
a correction to the velocity of the solitary wave at the corresponding order. The
variations of Mach number and width of the ion-acoustic soliton with amplitude at
each order are shown graphically for plasmas with H+ and He+ or with He+ and
Ar+ ions, with two-temperature non-isothermal electrons.
Evolution of magnetic moment in the interaction of waves with
kinetically described plasmas
Authors: DAS CHANDRA
Published: July 2002

The non-oscillating part of the magnetic moment field (called the
inverse
Faraday effect (IFE) for this field from a circularly polarized wave in
a medium)
is calculated for the interaction of an elliptically polarized wave with
a weakly
ionized magnetized plasma in a kinetic theory model and with unmagnetized
Vlasov plasmas. For a weakly ionized magnetized plasma, the induced field
increases with both temperature and ambient magnetic field. For an
unmagnetized plasma, it increases parabolically with temperature. The induced
magnetic field is found to vary parabolically with temperature in the case
of an
unmagnetized Vlasov plasma.
Nonlinear dynamics of fast magnetosonic
waves ducted by a smooth plasma inhomogeneity
Authors: NAKARIAKOV V. M. , ROBERTS B. , PETRUKHIN N. S.
Published: July 2002

The weakly nonlinear dynamics of fast magnetosonic waves ducted
by a region
of density enhancement in a cold plasma is considered. A self-consistent
2D
quasi-hyperbolic equation with quadratic and cubic nonlinearities is
derived for perturbations of the transverse component of the plasma velocity.
For a wave package with
a narrow spectrum, the governing equation is reduced to the nonlinear
Schrödinger
equation, whose structure is independent of the detailed density profile
provided
that it has a maximum (to be a potential well for the waves). The derived
equation
allows us to take into account the effect of the shape and steepness of
the density
profile on the wave dynamics.
Stationary operating density profiles in a crossed-field amplifier
Authors: KAUP D. J. , THOMAS GARY E.
Published: July 2002

We demonstrate with numerical WKB solutions that stationary density
profiles
can exist in a crossed-field amplifier. These are density profiles that
can exist in
equilibrium with a high-frequency (RF) wave propagating in the slow-wave
structure.
These density profiles are very different from the usual Brillouin profiles.
They
have a finite and negative density gradient, and extend from the cathode
to the
anode. They carry a DC current proportional to the RF power in the slow-wave

structure. The source of the DC current is a wave–particle resonance
that occurs
toward the top of the sheath. This resonance drives any Brillouin electron
flow
unstable. The electrons then redistribute themselves into a new flow –
one that can
be stationary in the presence of the wave–particle resonance. The
new flow has a
spoke-like structure, where the spokes carry the current to the anode.
Various plots
are given, including the DC voltage operating range, DC current flow, phase
shifts,
and density profiles of the total electron distribution, for various ambient
magnetic
fields and DC voltages. Numerical values agree reasonably well with the
modelled
experimental device.
Growth and saturation of the
Kelvin–Helmholtz instability with parallel
and antiparallel magnetic fields
Authors: KEPPENS RONY , TÓTH G. , WESTERMANN R. H. J. , GOEDBLOED J. P.
Published: July 2002

We investigate the Kelvin–Helmholtz instability occurring
at the interface of a
shear-flow configuration in 2D compressible magnetohydrodynamics (MHD).
The
linear growth and the subsequent nonlinear saturation of the instability
are
studied numerically. We consider an initial magnetic field aligned with
the shear
flow, and analyse the differences between cases where the initial field
is unidirectional
everywhere (uniform case) and those where the field changes sign at the
interface
(reversed case). We recover and extend known results for pure hydrodynamic

and MHD cases, with a discussion of the dependence of the nonlinear saturation

on the wavenumber, the sound Mach number and the Alfvénic Mach number
for
the MHD case. A reversed field acts to destabilize the
linear phase of the Kelvin–Helmholtz instability compared with the
pure
hydrodynamic case, while a uniform
field suppresses its growth. In resistive MHD, reconnection events almost
instantly
accelerate the build up of a global plasma circulation. They play an important
role
throughout the further nonlinear evolution as well, since the initial current
sheet is
amplified by the vortex flow and can become unstable to tearing instabilities,
forming
magnetic islands. As a result, the saturation behaviour and the overall
evolution
of the density and the magnetic field are markedly different for the uniform
versus
the reversed-field case.
Relativistic self-focusing of a rippled laser beam
in a plasma
Authors: ASTHANA M. V. , GIULIETTI A. , VARSHNEY DINESH , SODHA M. S.
Published: July 2002

This paper presents an analysis of the relativistic self-focusing of a
rippled Gaussian laser beam in a plasma. Considering the nonlinearity as arising
owing to relativistic variation of mass, and following the WKB and paraxial-ray approximations, the phenomenon of self-focusing of rippled laser beams is
studied for arbitrary magnitude of nonlinearity. Pandey et al.
[Phys. Fluids82,
1221 (1990)] have shown that a small ripple on the axis of the main beam grows
very rapidly with distance of propagation as compared with the self-focusing of
the main beam. Based on this analogy, we have analysed relativistic self-focusing of rippled beams in plasmas. The relativistic intensities with saturation
effects of nonlinearity allow the nonlinear refractive index in the paraxial
regime to have a slower radial dependence, and thus the ripple extracts
relatively less energy from its neighbourhood.
Articulatory dynamics of vowels and consonants in speech communication
Authors: Kohler Klaus J.
Published: July 2002

This paper provides a statistical account of schwa elision and vowel nasalization, and of nasalization and deletion of plosives in a large corpus of German spontaneous dialogues in comparison with an equally large data base of read speech (sentences and texts) from large groups of North German speakers. The phonetic variability of these phrase-level processes is projected onto the articulatory dynamics in global opening and closing gestures, which are taken to be basic phonetic structures of speech communication. Trends for gesture reorganization are derived from statistics, and related to external control factors of word boundary, word class, speech style as well as internal phonetic conditions of gestural make-up and of reduction of articulatory complexity. These synchronic facts of one language are compared with parallel instances from other languages and linked to congruent diachronic data of sound change, thus laying the foundation for generalizable phrase-level patterns of human speech production.
Enlightenment and Unity: Language Reformism in Late Qing China
Authors: CHENG W. K.
Published: July 2002

The movement to create a phonetic script for the Chinese language was arguably one of the most arresting and exciting
engagements in modern China. While generations of Chinese intellectuals tirelessly applied themselves to sorting out
the linguistic technicalities in devising a Chinese phonetic system, what made language reform—or, depending on the
perspective taken, revolution—historically so intriguing was that it had been a fiercely contested domain where a
fascinating array of ideological positions was staked and contended. As John de Francis has observed, there had always
been ‘a significant correlation between attitudes toward social change and attitudes toward linguistic reform in China’.
Indeed, Qian Xuantong insisted at the height of the May Fourth New Culture Movement that to destroy Confucianism,
one must ‘first dispose of the Chinese language’, whereas the Communist-led latinization movement of the 1930s,
for its part, was meant to create a medium for the emergence of a true proletarian culture.
Korea, China, and Western Barbarians: Diplomacy in Early Nineteenth-Century Korea
Authors: HARA TAKEMICHI
Published: July 2002

The story of the ‘opening’ of Korea presents us with a peculiar problem of its own. For, when Westerners arrived on the shores of Korea in the nineteenth century, they found a country that was shielded in the shadow of China. Korea, so it seemed to Westerners, would not open the country without Chinese approval, but China would not interfere in Korea on Western countries' behalf or, at times, even on her own behalf. And both Korea and China professed that they were acting according to the dictates of the traditional relationship which had bound the two countries for many centuries in peace and harmony. To Western observers this traditional Sino-Korean relationship seemed to offer nothing but a diplomatic cul-de-sac. Under the circumstances, it is not surprising that Western diplomats concluded that this relationship was merely ceremonial and largely dismissed it as having little political consequence.
The Naning War, 1831-1832: Colonial Authority and Malay Resistance in the Early Period of British Expansion
Authors: CHEW EMRYS
Published: July 2002

The Naning War, long dismissed by historians as a ‘little war’, was part of a more expansive drama in the history of the Malay world. The war expressed traditional modes of power-broking and opposition, as well as anticipated later political developments in Malaya. From the wider perspective of imperial history, this important but neglected episode of British expansion in the East merits a modern treatment. This article seeks to rectify deficiencies of existing histories of the Naning War by exploring the nature of indirect rule and formal control from the metropolis, and authority and conflict at the ‘periphery’. It sets the war both within the cultural context of Malay warfare, and within the regional context of indigenous resistance and Islamic protest against British incursions.
PETER AS PETER IN THE GOSPEL OF MARK
Authors: WIARDA TIMOTHY
Published: July 2002

Scholars tend to view the Markan Peter as a relatively impersonal figure, to a large extent blended with the group of the disciples. The idea that first-century society possessed a weak sense of the individual, the prevalence of typical figures in Greek literature, the special nature of the Gospel material, and Mark's lack of attention to Peter's future role are factors which contribute to this perspective. A survey of Mark's characterization of Peter, however, and comparison with the evangelist's portrayal of other disciples and the disciples as a group, reveals a distinctive figure and significant elements of individual human experience.
Factors affecting the component community structure of haemoparasites in bank voles (Clethrionomys glareolus) from the Mazury Lake District region of Poland
Authors: BAJER A. , PAWEŁCZYK A. , BEHNKE J.M. , GILBERT F.S. , SINSKI E.
Published: July 2002

The prevalence and abundance of infections with haemoparasites were studied over a 3 year period in Clethrionomys glareolus (bank vole, n=420) sampled from forests in the NE of Poland. Total species richness was 5 (Prevalence=Haemobartonella sp. 63·1%, Bartonella grahamii 27·4%, Hepatozoon erhardovae 31·4%, Trypanosoma evotomys 15% and Babesia microti 1·0%) with 81·9% of the voles carrying at least 1 species and a mean infracommunity species richness of 1·4. Variation in species richness was determined primarily by season and year, and the interaction of these factors. The observed frequency distribution of infracommunity species richness did not differ from that predicted by a null model, suggesting that there were no marked associations between the species. Analyses of prevalence and abundance of infection with each species in turn, revealed that overall the principal causes of variation were temporal and seasonal and their interaction, intrinsic factors such as age and sex playing only a minor role. However, the relative importance of specific extrinsic, and rarely intrinsic, factors varied and was distinct for each of the species in the study. Prevalence data revealed 4 sets of 2-way associations between species, mostly varyingly dependent on combinations of intrinsic and extrinsic factors. Analysis of quantitative associations suggested 4 sets of positive 2-way interactions, 3 of which remained after controlling for the effect of extrinsic and intrinsic factors on the abundance of each species, but only one could be unequivocally accepted (Haemobartonella sp.+B. grahamii) after correction for multiple comparisons. These data are discussed in the context of the changing ecological profiles in this region of Eastern Europe and, in a wider context, in relation to current understanding of the factors which shape component community structures of haemoparasites in wild rodents.
Physiological effects of FMRFamide-related peptides and
classical transmitters on dispersed muscle fibres of the
turbellarian, Procerodes littoralis
Authors: MONEYPENNY C. G. , KRESHCHENKO N. , MOFFETT C. L. , HALTON D. W. , DAY T. A. , MAULE A. G.
Published: July 2002

The physiological effects of selected classical transmitters and FMRFamide-related peptides (FaRPs) on dispersed muscle
fibres from the marine turbellarian, Procerodes littoralis have been examined. Confocal scanning laser microscopy coupled
with fluorescein isothiocyanate (FITC) or tetramethylrhodamine (TRITC)-labelled phalloidin revealed a highly developed
body wall muscle system with circular, longitudinal and diagonal layers of muscle fibres. Dispersed muscle fibres
contracted when depolarized by exposure to extracellular media with elevated K+ (15–100 mM) in a
concentration-dependent manner, with a maximal response of 87% achieved at [ges ] 75 mM. 5-Hydroxytryptamine (5-HT) induced
concentration-dependent muscle contraction between 0·01 and 1000 μM, with 10 μM producing a near maximal contraction
response of 75%. Acetylcholine (ACh) had less pronounced excitatory effects (0·01–1000 μM), inducing contraction of
only 32% of the fibres at 100 μM. The flatworm FMRFamide-related peptides (FaRPs), GYIRFamide, YIRFamide and
GNFFRFamide each had concentration-dependent myocontractile effects, indicating the occurrence of at least 1 FaRP
receptor on P. littoralis muscle fibres. At 10 μM peptide, GNFFRFamide induced contractions in < 40% of the muscle
fibres examined, whereas YIRFamide and GYIRFamide induced contraction in 70 and 75%of muscle fibres, respectively.
The order of potency of the peptides was: GYIRFamide > YIRFamide > GNFFRFamide. Pre-incubation of the muscle
fibres in 5 μM 5-HT significantly reduced the responses to GYIRFamide, YIRFamide and 5-HT, while the responses to
high K+ remained unaltered. Muscle fibres pre-incubated in GYIRFamide (0·1 μM) were also less responsive to 5-HT but
not to ACh and high-K+. The GYIRFamide analogue, GYIRdFamide, did not induce muscle contraction (0·01–100 μM)
per se, but when co-applied with the myoactive peptides GYIRFamide, YIRFamide or GNFFRFamide, it significantly
blocked their ability to elicit contractions. This suggests that the peptides tested may act via a common muscle-based
neuropeptide receptor. GYIRdFamide did not alter the contractile effects of high K+, 5-HT or ACh. Collectively, these
results indicate that FaRPs, 5-HT and ACh all have the potential to cause muscle contraction in flatworms and that
5-HT and FaRPs alter muscle sensitivity to each other, but do not influence the ability of flatworm muscle fibres to
contract.
The Egyptian mongoose,Herpestes ichneumon, is a possible reservoir host of visceral leishmaniasis in eastern Sudan
Authors: ELNAIEM D. A. , HASSAN M. M. , MAINGON R. , NURELDIN G. H. , MEKAWI A. M. , MILES M. , WARD R. D.
Published: July 2002

Investigations were made on possible reservoir hosts ofLeishmania donovaniin 2 zoonotic foci of visceral leishmaniasis (VL) in Dinder National Park (DNP) and the peri-domestic habitats of adjacent villages of eastern Sudan. Animals were captured, in November 1997–1998 and April–May 1999 and examined forL. donovaniinfection using light microscopy and 2 sensitive Polymerase Chain Reaction (PCR) systems. Microscopy and PCR investigations were also used to determine the infection rates ofL. donovaniinPhlebotomus orientaliscaptured from the uninhabited site of DNP. Infections ofL. donovaniwere detected in 2 out of 14 Egyptian mongooses (Herpestes ichneumon), 1 out of 168Arviconthus niloticusand 1 out of 8Mastomys natalensis. Samples from 68 other animals captured from the study area were all negative for the infection. Active zoonotic transmission ofL. donovaniat the time of animal sampling in the uninhabited site of DNP was demonstrated by finding the parasite in 3.4% (7 out of 184) and 3.2% (5 out of 157) of flies collected in March 1998 and May 1999, respectively. We suggest that the Egyptian mongoose is a possible reservoir host ofL. donovani. The importance of other animals in maintaining the infection is also discussed.
Decrease of psychomotor performance in subjects with latent ‘asymptomatic’ toxoplasmosis
Authors: HAVLÍČEK J. , GAšOVÁ Z. , SMITH A. P. , ZVÁRA K. , FLEGR J.
Published: July 2002

Toxoplasma gondiiis known to induce specific behavioural changes in its intermediate hosts. This is usually considered to be an evolutionary adaptation aimed to increase the probability of transmission of the parasite into its definitive host, the cat, by predation. In rodents an increase of reaction time as well as many other specific behavioural patterns have been observed. Here we report the results of our double blind study showing the significantly longer reaction times of 60 subjects with latent toxoplasmosis in comparison with those of 56 controls. Moreover, the existence of a positive correlation between length of infection and mean reaction time suggested that slow and cumulative effects of latent toxoplasmosis rather than a one-step (and possibly transient) effect of acute toxoplasmosis disease are responsible for the decrease of psychomotor performance of infected subjects. To our knowledge, this is the first study confirming the existence of such parasite-induced changes in human behaviour that could be considered in evolutionary history of the human species as adaptive from the point of view of parasite transmission.
Molecular genetic analysis of human cystic hydatid cases from Poland:
identification of a new genotypic group (G9) of Echinococcus granulosus
Authors: SCOTT J. C. , STEFANIAK J. , PAWLOWSKI Z. S. , McMANUS D. P.
Published: July 2002

We have used nuclear (ribosomal ITS1) and mitochondrial (ND1) sequences
to characterize human and pig isolates of Echinococcus granulosus
collected by fine needle aspiration biopsy (FNAB) in Poland. The data indicate
clearly that the Polish patients were not infected with the common sheep
strain (G1 genotype) of E. granulosus, normally associated with
human cystic hydatid infection. Instead, the hydatid parasite infecting
the Polish patients shares very similar ND1 sequence with the previously
characterized pig (G7) genotype but it also exhibits some clear differences.
In particular, E. granulosus DNA from the Polish patients amplified
a single ITS1 fragment in PCR and distinct ITS1–RFLP patterns were
obtained after restriction digestion. The form of hydatid isolated from
the Polish patients appears, therefore, to represent a distinct, previously
undescribed genotype (designated G9) of E. granulosus.
Seasonal dynamics of Pneumocystis carinii in the field vole,

Microtus agrestis, and in the common shrew, Sorex
araneus, in Finland
Authors: LAAKKONEN J. , HENTTONEN H. , NIEMIMAA J. , SOVERI T.
Published: July 2002

Seasonal dynamics of Pneumocystis carinii in the field
vole, Microtus agrestis, and in the common shrew, Sorex araneus,

were investigated in southern and central Finland by microscopical examination
of methenamine silver-stained tissue
sections. In both host species at both localities the number of P.
carinii cyst forms was highest in late autumn (November).
In S. araneus, prevalence was higher than in M. agrestis
during all seasons. None of the animals was heavily infected or
apparently ill, and neither species showed any extrapulmonary dissemination.
In this study covering an increase phase and
4 peak host-density phases of the vole cycle, the occurrence of P.
carinii seemed to be related to the population density
of M. agrestis.
Epidemiology of an intestinal parasite (Spirometra spp.)
in
two populations of African lions (Panthera leo)
Authors: MÜLLER-GRAF C. D. M. , WOOLHOUSE M. E. J. , PACKER C.
Published: July 2002

Infection with the cestode Spirometra spp. was studied
in 2 populations of lions in the Serengeti and the Ngorongoro
Crater in Tanzania, East Africa. These 2 lion populations lived in different
habitats and were known to differ genetically:
lions in the Serengeti were outbred, whereas lions in the Ngorongoro Crater
were inbred. Faecal samples were collected
from 112 individually known lions between March 1991 and November 1992.
Over 60% of lions were infected and the
median intensity of infection was 975 eggs per g of faeces. The distribution
of egg counts was overdispersed. There was
variability through time, though this was unrelated to seasons delimited
by rainfall. There were no significant differences
in levels of infection between age classes; cubs less than 9 months were
already heavily infected. Sex and reproductive
status did not have a significant effect. However, there were significant
differences in intensities of infection between the
Crater and the Serengeti populations – Spirometra spp. showed
a higher level of infection intensity in the Crater population
– with some variation between prides within these populations. Allozyme
heterozygosity scores were available for a subset
of 28 lions but were unrelated to levels of Spirometra infection.
It was not possible to ascribe differences in levels of
parasite infection to genetic rather than ecological factors.
Can prevalence of infection in school-aged children be
used as an index for assessing community prevalence?
Authors: GUYATT H. L. , BROOKER S. , DONNELLY C. A.
Published: July 2002

Community data on the prevalence of helminth infections is important
for guiding health policy, but expensive to collect.
As a result most surveys focus on school-aged children, frequently using
schools as a sentinel population. Since there
already exists a vast amount of data on infection levels in school-aged
children, but limited community-based data, we
undertook a literature search on age-stratified infection data for intestinal
nematode infections and schistosomiasis in
Africa, to investigate whether estimates of the prevalence of infection
in school-aged children could provide an index for
determining community prevalence. The observed data on prevalence of infection
in infants, school-aged children and
adults were fitted using linear and logistic regression models which take
into account variation in sample prevalences.
Despite the wide variation in study sites, the observed relationship between
community prevalence and school-aged
prevalence was remarkably consistent for each parasite species. The prevalence
of infection in school-aged children alone
was shown to be higher than the predicted prevalence in the community,
but the degree of overestimation was dependent
on the parasite species and the level of infection. The results suggest
that the prevalence of infection in school-aged children
could provide a cost-effective predictive tool which can be used at a district/national
level to identify target areas for
control and to evaluate the numbers at risk of infection.
Development of monogenean communities on the gills of
roach fry (Rutilus rutilus)
Authors: BAGGE A. M. , VALTONEN E. T.
Published: July 2002

The formation and development of monogenean communities on the gills of roach fry was followed in 1992 from early
June to October (size range 9 to 47 mm). Roach fry (n=291) were sampled weekly from the small, humic River Rutajoki
in central Finland. A further 209 roach fry were reared in a fish farm supplied by water from the river. Four Dactylogyrus
species were found: D. nanus, D. crucifer, D. micracanthus and D. suecicus. Other species found on the gills were
Gyrodactylus sp. and Paradiplozoon homoion. The first Dactylogyrus juvenile occurred on a 12 mm long fish fry in late June
and the first adult (D. nanus) 1 week later in Tank 1. D. nanus was also the most common parasite in the river. Young fry
had high numbers of Gyrodactylus sp. on the gills compared with adult roach in previous studies. Signs of site preference
were found; D. nanus and D. micracanthus preferred the 2nd gill-arch and Dactylogyrus juveniles the outmost one.
Abundances of monogenean infracommunities increased until the middle of August when, on average, 1·9 species and 3·7
worms per fry were noted and decreased then as the water temperatures fell. A lack of competition between species is
suggested; for example, D. crucifer appeared on the gills at that time when abundance of D. nanus was at its highest. The
roach fry hatched and reared in the fish farm revealed that larvae of the most common dactylogyrid species were able to
disseminate and colonize over 120 m from the river to the farm. Influence of change colonization events was shown by
the appearance and development of Gyrodactylus sp. population on roach fry in only 1 of the 2 tanks at the farm.
Desiccation tolerance of Muellerius capillaris first-stage
larvae from Israeli arid and French temperate habitats
and their compatibility to the land snail Theba pisana
Authors: SOLOMON A. , CABARET J. , GLAZER I. , PAPERNA I.
Published: July 2002

The survival capacities of Muellerius capillaris (Nematoda: Protostrongylidae) free-living larval stages (L1) of an Israeli
desert isolate (Nubian isolate) (92 mm rain per annum) and a French isolate from a temperate habitat (650 mm rain per
annum) were compared under humid and extreme dry conditions. Under the dry conditions (7% relative humidity [r.h.]
and 33% r.h. at 23 °C), both isolates exhibited the same remarkable survival capacity for periods of 17 and 28 days,
respectively (>92% survival, P>0·1). However, during and after recovery from the anhydrobiotic state, different
behaviour patterns of L1 were observed in each isolate. Under humid conditions (97% r.h.) for 10 days, both isolates
exhibited similarly low survival percentages (13·4±4·6%, S.E., survival for the Nubian isolate, 3±3% for the French
isolate, P>0·05). In water, the French isolate was less active, survived better (52±8·4% vs 28·7±3·7, by day 28,
P<0·05) and retained a better morphological appearance (shrunk less) than the Nubian isolate. Larval development of
the French isolate in the land snail Theba pisana was significantly faster than that of the Nubian isolate, reaching a higher
proportion of infective stages (L3) on day 36 post-infection (78·6% vs 56% P>0·05). However, similar infection
intensities were recovered in snails infected with either of the isolates (59·8±10·3, S.E., n=14, for the French isolate,
53±6, n=13, for the Nubian isolate, P<0·05).
Detection of Theileria annulata in cattle and vector ticks
by PCR using the Tams1 gene sequences
Authors: KIRVAR E. , ILHAN T. , KATZER F. , HOOSHMAND-RAD P. , ZWEYGARTH E. , GERSTENBERG C. , PHIPPS P. , BROWN C. G. D.
Published: July 2002

A Polymerase Chain Reaction (PCR) and Southern blot hybridization for the detection of Theileria annulata are described.
The PCR used primers amplifying a 785 base-pair fragment of the T. annulata gene which encodes the 30 kDa major
merozoite surface antigen, Tams1. The sensitivity of the PCR in bovine blood was 1 piroplasm in 1 μl of blood. T. buffeli,
T. parva, Babesia bigemina, B. bovis and B. divergens were not detected. The PCR detected down to 1 infected acinus/tick
in resting and partially fed adult Hyalomma anatolicum anatolicum ticks and was negative for T. lestoquardi and T. equi,
which are transmitted by this tick but are not infective to cattle. The specificity of the PCR was checked using 30 stocks
of T. annulata, all of which were detected. Three stocks of T. lestoquardi, 4 of T. equi and 1 each of T. buffeli, T. parva,
B. bigemina, B. bovis and B. divergens were used to ascertain there were no cross-reactions. A nested PCR using separate
primers for the first reaction and the same primers for the second reaction detected T. annulata to the same sensitivity
and specificity in saponin-extracted DNA samples stored for long periods at −20 °C.
Simulating Dictyocaulus viviparus infection in calves: the parasitic phase
Authors: PLOEGER H. W. , EYSKER M.
Published: July 2002

A model simulating Dictyocaulus viviparus infection in calves is described. The present paper only deals with the parasitic
phase of the life-cycle. Descriptions are given for establishment, development rate of juvenile stages, mortality rates of
both juvenile and adult stages, and fecundity. Literature data were used to to develop parameter functions and to estimate
initial values for constants. Development of acquired immunity, defined as the proportional ability of the host to reduce
the number of parasite individuals in some stage or about to move into a next stage, against establishment (protection)
or affecting mortality rates of juvenile or adult parasite stages has been included. The effect of immunity on one parameter
or process is viewed as distinctly separate from the effect on another. Preliminary comparisons between model prediction
and observations gives encouraging results, indicating that the model simulates experimental D. viviparus infection in
calves reasonably well. Some quantitative discrepancies between prediction and observation make clear however, that not
all parts of the model are accurate. Further experimentation is needed to re-evaluate current model description and to
improve model simulation.
Impact of asymptomatic malaria parasitaemia on cognitive
function and school achievement of schoolchildren in the
Yemen Republic
Authors: AL SEROURI A. W. , GRANTHAM-McGREGOR S. M. , GREENWOOD B. , COSTELLO A.
Published: July 2002

Asymptomatic malaria parasitaemia is prevalent among schoolchildren in many countries. The relationship between
asymptomatic parasitaemia and children's cognitive functions was examined in a case control study and then in a natural
experiment. A group (n = 445) of asymptomatic parasitaemic boys were compared with a group of non-parasitaemic boys
(n = 142) matched for grade and school on their performance on a battery of cognitive tests. Two weeks later the
parasitaemic children were re-screened and 150 children of those who remained parasitaemic were matched for grade and
school with 150 children who were no longer parasitaemic. These children were then re-tested and their cognitive function
compared. Initially, after controlling for age, socio-economic background and nutritional status the parasitaemic children
performed worse than the non-parasitaemic children in fine motor function tests. There was no difference in change in
cognitive test scores between those who became non-parasitaemic and those who remained parasitaemic. However,
children who initially had the highest parasite density improved the most in 2 fine motor tests and a picture memory test.
We were unable to show a benefit from losing parasitaemia over a 2 week period, but it remains possible that parasitaemia
may affect cognition and longer term trials should be conducted.
Understanding People
Authors: Cooper Neil
Published: July 2002

The division between “erklaren” and “verstehen” is not as sharp as the conventional wisdom maintains, for all understanding, including the understanding of people, consists in the connecting, ordering and appraising of things encountered, believed or known. The understanding of people is a distinctive kind of cognitive understanding which has a practical side, involving the emotions. The education of the emotions, needed for us to understand ourselves and others, can be achieved both by the observation of real life and importantly by the study of realistic fiction and of biography.
Incidence of suicide ideation and attempts in adults: the 13-year follow-up of a community sample in Baltimore, Maryland
Authors: KUO WEN-HUNG , GALLO J. J. , TIEN A. Y.
Published: July 2002

Background. Utilizing a prospectively designed community sample, we set out to estimate the rate of newly-incident suicidal ideation and attempts (non-fatal suicide behaviour) in a community sample, to evaluate antecedent sociodemographic characteristics and psychiatric disorders, and to assess use of mental health services in relation to non-fatal suicide behaviour.

Method. Prospectively-gathered data was utilized from 3481 continuing participants in the 13-year follow-up of the Baltimore sample of the NIMH Epidemiologic Catchment Area survey interviewed in 1981, 1982 and 1993/6.

Results. The incidence of suicide attempts was estimated at 148·8 per 100000 person-years and ideation at 419·9 per 100000 person-years. Persons in the youngest age group, in the lowest socio-economic status, and previously married persons were at increased risk for non-fatal suicide behaviour during the follow-up interval. Persons who reported suicidal ideation at baseline were more likely to report having attempted suicide at follow-up (RR = 6·09, 95% CI 2·58–14·36). Psychiatric disorders, especially depression and substance abuse, were associated with new-onset of non-fatal suicidal behaviour. While persons who reported newly-incident suicidal behaviour were more likely to report use of mental health services, few said that suicidal ideation or attempts were the reason for the visits.

Conclusions. Suicidal ideation is a common and important antecedent to suicide attempts and deserves more attention in community and general medical settings.