bluuebunny/crossref_metadata_2025 huggingface dataset:
Solidifying Bingham extrusions: a model for the

growth of silicic lava domes
Authors: GRIFFITHS ROSS W. , FINK JONATHAN H.
Published: July 2002

In a previous study of the effects of cooling and solidification
on

flows issuing onto a

horizontal plane and spreading under gravity we considered the case of

a viscous fluid

that solidifies to form a thin surface crust with a finite yield strength.

In that case, the

coupling of solidification and viscous stresses in the flow led to

a sequence of flow

regimes or styles of flow and crustal deformation. Here, we study

the spreading, from

a small source, of a plastic material having a yield strength before

cooling. In this case

the fluid again begins to freeze as it spreads radially under

gravity, and forms a dome

having a surface crust which is stronger than the extruded fluid.

If cooling is sufficiently

rapid compared to gravity-driven spreading, the flow is found to be controlled
by

solidification. The flow again takes on one of a number of flow regimes
depending on

the pace of solidification relative to the rate of lateral flow, or extrusion
rate.

However, these flow regimes are quite different from those

for the viscous extrusions,

implying that the internal yield stress has a strong influence on

the behaviour. Styles

of flow ranged from inflation of an axisymmetric dome to irregular

extrusion of lateral

lobes and vertical spines. These qualitatively different regimes have much
in common

with the eruption styles of volcanic lava domes produced by effusion of
extremely

viscous silicic magmas which may possess a yield strength, and the model
provides

information about the factors influencing the morphology and hazards of
such

volcanic flows.
Turbulent mixing in a shear-free stably stratified

two-layer fluid
Authors: BRIGGS DAVID A. , FERZIGER JOEL H. , KOSEFF JEFFREY R. , MONISMITH STEPHEN G.
Published: July 2002

Direct numerical simulation is used to examine turbulent

mixing in a shear-free

stably stratified fluid. Energy is continuously supplied to a

small region to maintain

a well-developed kinetic energy profile, as in an oscillating grid

flow (Briggs et al.

1996; Hopfinger & Toly 1976; Nokes 1988). A microscale

Reynolds number of 60

is maintained in the source region. The turbulence forms a well-mixed

layer which diffuses from the source into the quiescent fluid below.

Turbulence transport at the

interface causes the mixed layer to grow under weakly stratified

conditions. When

the stratification is strong, large-scale turbulent transport is

inactive and pressure

transport becomes the principal mechanism for the growth of the

turbulence layer.

Down-gradient buoyancy flux is present in the large scales; however,

far from the source, weak counter-gradient fluxes appear in the medium
to

small scales. The production of internal waves and counter-gradient fluxes

rapidly reduces the mixing

when the turbulent Froude number is lower than unity. When the

stratification is weak,

the turbulence is strong enough to break up the density interface

and transport fluid

parcels of different density over large vertical distances. As the

stratification intensifies,

turbulent eddies flatten against the interface creating anisotropy

and internal waves. The dominant entrainment mechanism is then scouring.

Mixing efficiency, defined as

the ratio of buoyancy flux to available kinetic energy, exhibits a

similar dependence

on Froude number to other stratified flows (Holt et al.

1992; Lienhard & Van Atta

1990). However, using the anisotropy of the turbulence to

define an alternative

mixing efficiency and Froude number improves the correlation and

allows local scaling.
Square cells in surface-tension-driven Bénard

convection: experiment and theory
Authors: ECKERT KERSTIN , BESTEHORN MICHAEL , THESS ANDRÉ
Published: July 2002

The convective flow in a thin liquid layer with a free

surface heated from below is

studied using a combination of accurate experiments with

silicone oil (v=0.1 cm2 s−1)

and high-resolution direct numerical simulations of the

time-dependent governing equations. It is demonstrated that above

a certain value εs of the threshold of

primary instability, ε=0, square convection cells

rather than the seemingly all-embracing

hexagons are the persistent dominant features of

Bénard convection. The transition

from hexagonal to square cells sets in via a subcritical

bifurcation and is accompanied

by a sudden rapid increase of the Nusselt number. This

implies that square cells are the

more efficient mode of heat transport. Their wavenumber

exceeds that of hexagonal

cells by about 8%. The transition depends on the Prandtl

number and it is shifted

towards higher εs if the Prandtl

number is increased. The replacement of hexagonal

by square cells is mediated by pentagonal cells. In the

transitional regime from

hexagonal to square cells, characterized by the presence of

all three planforms, the

system exhibits complex irregular dynamics on large spatial

and temporal scales. The

time dependence becomes more vivid with decreasing Prandtl

number until finally

non-stationary square cells appear. The simulations agree

with the experimental

observations in the phenomenology of the transition, and

in the prediction of both

the higher Nusselt number of square Bénard cells and

the subcritical nature of

the transition. Quantitative differences occur with

respect to the values of εs and

the Prandtl number beyond which the time dependence vanishes.

These differences are the result of a considerably weaker

mean flow in the simulation and of residual

inhomogeneities in the lateral boundary conditions of the

experiment which are below the threshold of control.
Analysis and modelling of subgrid-scale motions

in near-wall turbulence
Authors: HÄRTEL CARLOS , KLEISER LEONHARD
Published: July 2002

A numerical study of turbulent channel flow at

various Reynolds numbers (Reτ=115,

210, 300) is conducted in order to examine the requirements

for a reliable subgrid

modelling in large-eddy simulations of wall-bounded flows.

Using direct numerical

simulation data, the interactions between large and small

scales in the near-wall

flow are analysed in detail which sheds light on the origin

of the inverse cascade of

turbulent kinetic energy observed in the buffer layer. It is

shown that the correlation

of the wall-normal subgrid stress and the wall-normal

derivative of the streamwise

grid-scale velocity plays the key role in the occurrence

of the inverse cascade. A

brief a priori test of several subgrid models shows

that currently applied models are

not capable of accounting properly for the complex interactions

in the near-wall

flow. A series of large-eddy simulations gives evidence that

this deficiency may cause

significant errors in important global quantities of the

flow such as the mean wall

shear stress. A study of the eddy-viscosity ansatz is

conducted which reveals that

the characteristic scales usually employed for the definition

of the eddy viscosity

are inappropriate in the vicinity of a wall. Therefore, a

novel definition of the eddy

viscosity is derived from the analysis of the near-wall

energy budget. This new

definition, which employs the wall-normal subgrid stress

as a characteristic scale, is

more consistent with the near-wall physics. No significant

Reynolds-number effects

are encountered in the present analysis which suggests

that the findings may be

generalized to flows at higher Reynolds numbers.
Similarity in non-rotating and rotating turbulent
pipe flows
Authors: OBERLACK MARTIN
Published: July 2002

The Lie group approach developed by Oberlack (1997) is used to
derive new scaling
laws for high-Reynolds-number turbulent pipe flows. The scaling laws, or,
in the
methodology of Lie groups, the invariant solutions, are based on the mean
and
fluctuation momentum equations. For their derivation no assumptions other
than
similarity of the Navier–Stokes equations have been introduced where
the Reynolds
decomposition into the mean and fluctuation quantities has been implemented.
The
set of solutions for the axial mean velocity includes a logarithmic scaling
law, which
is distinct from the usual law of the wall, and an algebraic scaling law.
Furthermore,
an algebraic scaling law for the azimuthal mean velocity is obtained. In
all scaling
laws the origin of the independent coordinate is located on the pipe axis,
which is
in contrast to the usual wall-based scaling laws. The present scaling laws
show good
agreement with both experimental and DNS data. As observed in experiments,
it is
shown that the axial mean velocity normalized with the mean bulk velocity
um has
a fixed point where the mean velocity equals the bulk velocity independent
of the
Reynolds number. An approximate location for the fixed point on the pipe
radius
is also given. All invariant solutions are consistent with all higher-order
correlation
equations. A large-Reynolds-number asymptotic expansion of the Navier–Stokes

equations on the curved wall has been utilized to show that the near-wall
scaling laws
for at surfaces also apply to the near-wall regions of the turbulent pipe
flow.
Shear-flow instability in a rotating fluid
Authors: VAN DE KONIJNENBERG J. A. , NIELSEN A. H. , JUUL RASMUSSEN J. , STENUM B.
Published: July 2002

The instability of a forced, circular shear layer in a rotating fluid has been studied
experimentally and numerically. The experiments were performed with a shallow layer
of water in a parabolic tank, in which it is possible to apply radial pumping and to
model a geophysical beta-effect. A shear layer was produced by a secondary rotation
of the central part of the parabolic vessel. In most experiments, the shear layer
takes on the appearance of a sequence of vortices, the number of which decreases
with increasing strength of the shear. A beta-effect may prevent the formation of a
steady vortex chain. Continuous pumping of fluid from the periphery to the centre
or vice versa leads to an azimuthal velocity field corresponding to a point vortex.
This azimuthal flow appears to stabilize the shear flow if it is opposite to the inner
rotation, and to be destabilizing otherwise.

The numerical investigations consist of the solution of the quasi-geostrophic equation
in a geometry similar to the experimental situation and with a term modelling
the experimental forcing. Though the numerical computations are based on a two-dimensional model, they capture the essential features of the instability and the
resulting vortex structures.
On the breakup of an air bubble injected into a
fully developed turbulent flow.
Part 1. Breakup frequency
Authors: MARTÍNEZ-BAZÁN C. , MONTAÑÉS J. L. , LASHERAS J. C.
Published: July 2002

The transient evolution of the bubble-size probability density functions resulting
from the breakup of an air bubble injected into a fully developed turbulent water
ow has been measured experimentally using phase Doppler particle sizing (PDPA)
and image processing techniques. These measurements were used to determine the
breakup frequency of the bubbles as a function of their size and of the critical
diameter Dc defined as Dc =
1.26 (σ/ρ)3/5ε−2/5, where ε is the
rate of dissipation per unit mass and per unit time of the underlying turbulence. A
phenomenological model is proposed showing the existence of two distinct bubble size regimes.
For bubbles of sizes comparable to Dc, the breakup frequency is shown to increase as
(σ/ρ)−2/5ε−3/5
√D/Dc−1, while for large bubbles whose
sizes are greater than 1.63Dc, it decreases with the bubble size as
ε1/3D−2/3. The model is shown to be in good
agreement with measurements performed over a wide range of bubble sizes and turbulence
intensities.
Reynolds-number-independent instability of the boundary layer over a flat surface:
optimal perturbations
Authors: LUCHINI PAOLO
Published: July 2002

The dependence on initial conditions of the three-dimensional algebraic spatial instability
of the Blasius boundary layer is examined by a recently developed method
of receptivity analysis based on the upstream integration of adjoint equations. This
method allows us to determine optimal perturbations, i.e. initial perturbations that
maximize the energy growth, even in the wavenumber range where the problem is
not amenable to a mode analysis, and thus to complement a previous paper in which
the small-wavenumber regime was described.
Convection-driven dynamos in a rotating plane layer
Authors: JONES CHRIS A. , ROBERTS PAUL H.
Published: July 2002

The plane layer Childress–Soward dynamo model, consisting of a rotating layer of
electrically conducting fluid between horizontal planes heated from below, is studied.
Solutions periodic in the horizontal directions are sought, with electrically insulating
boundary conditions applied. The large Prandtl number limit is used.

Fully three-dimensional convection-driven dynamos have been studied numerically
for this problem. Both the kinematic and the magnetically saturated regimes are
studied, and a simple model of the dynamo mechanism is proposed. The dependence
of the dynamo on the Rayleigh number, Ekman number and diffusivity ratio is
studied, and the role of Taylor's constraint in low Ekman number convection-driven
dynamos is considered.
The New Faces of Informality in

Central America
Authors: PÉREZ SÁINZ J. P.
Published: July 2002

The current productive restructuring in Central America

is creating significant changes in the region's labour

markets. New sectors of tradeables are

emerging which, from the point of view of labour, cannot be

characterised as

formal. Indeed, formal employment is currently in a state

of decline while the

informal sector is redefining its internal heterogeneity.

This article focuses on the

new expressions of informality. Three scenarios are

identified: the economy of

poverty, subcontracting, and the agglomeration of small

dynamic enterprises.

Various analytical aspects are considered in each of

these three scenarios: the

context of the globalisation process; the type of informality;

the resources which

are mobilised; the challenges faced; and the identities

generated. The analysis is

based on the evidence supplied by three case studies. The

first refers to the former

public employees of Managua (Nicaragua) who, in the

aftermath of state reforms,

presently pursue informal activities. The second example

concerns a group of

women in the community of Puente Alto (Honduras) who work

as subcontracted

producers for an industrial export firm. Sarchí,

Costa Rica's principal artisan

centre, illustrates the third scenario.
The shadow-politics of Wolofisation
Authors: O'Brien Donal Cruise
Published: July 2002

The relationship between language and politics in the African post-colony remains obscure and underexamined. Here we withdraw into a
poorly lit area, an area of potentialities, where new political shapes
may
emerge as the outcome of half-conscious choices made by very large
numbers of people. Language choices in the first place: the expansion
of the Wolof language in Senegal, principally though far from
exclusively an urban phenomenon, is to be seen in a context where the
individual may speak several languages, switching linguistically from
one social situation to another. Such multilingualism is general in
Africa: the particularity of the Wolof case, at least in Senegal, is the

extent to which this language has spread, far beyond the boundaries of

core ethnicity, of a historical Wolof zone from the colonial or pre-colonial periods. And these individual language choices cast their
political shadow.

The political consequences of this socio-linguistic phenomenon are as

yet indistinct, but to see a little more clearly one should in the second

place relate it to the subject of the politics of ethnicity. Language is
of
course an important element in any definition of ethnicity, and there is

an evident overlap; but the politics of language is also a distinguishable

subject in its own right. Where the assertion of ethnic identity can be

identified as a possible weapon in the individual's struggle for power

and recognition within the colonial and post-colonial state, the choice

of a language is that of the most effective code in the individual's
daily
struggle for survival. Language choice in such a setting may be less a

matter of assertion, the proud proclamation of an identity, than it is
one
of evasion, a more or less conscious blurring of the boundaries of
identity. And in Senegal the government itself by its inaction has
practised its own shadow-politics of procrastination.
Derivation of an equation for three-wave
interactions based on the
Klimontovich–Dupree equation
Authors: EROFEEV V. I.
Published: July 2002

A collision integral for three-wave interactions in a collisionless
plasma is derived
from the full plasma description by means of the Klimontovich–Dupree
and
Maxwell equations. This collision integral differs from its traditional
counterpart (calculated within the framework of Vlasov theory) by an additional
functional factor.
This means that the changes in the wave spectral density, which are induced
by
three-wave interactions, occur with a rate other than that calculated in
Vlasov
theory.
Kelvin–Helmholtz instability of a plasma with anisotropic and

polytropic pressure laws
Authors: SHARMA P. K. , CHHAJLANI R. K.
Published: July 2002

The Kelvin–Helmholtz (K–H) instability of two fluids
of plasma streaming in
opposite directions with the same velocity and in the presence of an external

magnetic field is investigated. The usual magnetohydrodynamic equations
with
anisotropic pressure are considered. In the present problem, the two pressures

parallel and perpendicular to the direction of the magnetic field are defined
by
polytropic pressure laws. The generalized pressure relations are used,
and two
equations of state for two pressures are assumed. The equations are linearized,

and initially two different flow velocities are taken for the system. The
flow is
assumed to be in the direction perpendicular to the magnetic field. The
problem
is solved and a dispersion relation is obtained. From the dispersion relation,
the
K–H instability condition is obtained. It is found that the instability
condition
depends upon the polytropic indices of the pressure relations. The condition
of
instability is further obtained for MHD and Chew–Goldberger–Low
systems. It
is also found that the growth rate of the instability depends upon various

polytropic indices.
Dust acoustic solitons in a magnetized dusty plasma
Authors: MALIK H. K. , TRIPATHI K. D. , SHARMA S. K.
Published: July 2002

Propagation characteristics of dust acoustic solitons are studied
in a magnetized
dusty plasma consisting of ions, electrons and negatively charged dust
grains.
It is found that rarefactive solitons (solitons associated with negative

potentials) are possible in such a plasma. The effects on the soliton
characteristics of magnetic field strength, wave propagation angle, and
densities
and temperatures of the plasma particles are analysed.
A nonlinear equation for electron surface
waves at a plasma boundary
Authors: BYCHKOV V. V. , STENFLO L.
Published: July 2002

A nonlinear equation for electrostatic electron surface waves at
the boundary
between a cold plasma and a dielectric is derived. Our analysis of this
equation shows
that the nonlinear disturbances at the plasma–dielectric interface
may take the
form of periodic travelling waves or standing waves with oscillating amplitudes.

While the travelling waves are always periodic in space, the standing waves
can be
both periodic and localized.
Localising the Universal: Women, Motherhood and the Appeal of Early Theravāda Buddhism
Authors: Andaya Barbara Watson
Published: July 2002

This essay suggests that one reason for the success of Theravāda Buddhism in early Southeast Asia was its appeal to women. The maternal metaphor, a prominent theme in Buddhist texts, was both familiar and relevant to the lives of all females, regardless of their social standing. Translated into a local environment, the interaction between motherhood and merit-making provided new opportunities for lay women to display their piety and strengthened their links with the monkhood.
Some non-sequential phenomena in German function words
Authors: Wesener Thomas
Published: July 2002

Labellers of connected speech corpora encounter a number of cases which are difficult to handle with a linear sequence of segmental labels. Based on material from a corpus of German unscripted speech, this paper presents non-sequential aspects of laryngeal activity for /x/ and /h/, and of supralaryngeal articulation in vocoid exponents of postvocalic /r/. Comparative data for /r/ from a corpus of German read speech indicate that differences across speaking styles may be independent of durational variation. It is discussed how models of the phonology-phonetics interface and Prosodic Analysis can account for the findings.
Clicks in a Chinese nursery rhyme
Authors: Nathan Geoffrey S.
Published: July 2002

This paper reports on the use of nasalized post-alveolar clicks in a special version of a Chinese nursery rhyme, used in two different so-called dialect areas in China. In one, initial velar nasals are replaced with the clicks, while in Mandarin the nasalized clicks are inserted at the beginning of words with zero initials.
The structure and taxonomic composition of sublittoral meiofauna assemblages as an indicator of the status of marine environments
Authors: Schratzberger M. , Gee J.M. , Rees H.L. , Boyd S.E. , Wall C.M.
Published: July 2002

A study was conducted between 1997 and 1999 to investigate meiofauna assemblages from selected inshore and offshore locations around the UK coast. The main objective was to relate the differences in meiofauna distribution patterns to a number of measured environmental variables and to establish more clearly the sensitivity of meiofauna communities to anthropogenic disturbance. Results from univariate and multivariate data analyses show that distinct spatial differences in species distribution patterns exist and that these correlate with the natural physical characteristics and concentrations of trace metals in the sediment. Abundance and diversity of meiofauna assemblages were generally higher offshore than inshore and this difference can be attributed to both natural processes and anthropogenic impacts. The inclusion of meiofauna in applied monitoring programmes offers the potential for improving the resolution of the spatial extent of anthropogenic impacts over that achievable from macrofauna investigations alone.
Problems in extraction and spectrophotometric determination of chlorophyll from epilithic microbial biofilms: towards a standard method
Authors: Thompson R.C. , Tobin M.L. , Hawkins S.J. , Norton T.A.
Published: July 2002

A variety of methods are available to extract chlorophyll from epilithic biofilms using solvents. The relative efficiency of these has not been determined simultaneously and there is no recognized standard procedure. In this paper techniques for sample collection, storage, preparation and extraction are reviewed and compared experimentally.

Extraction of chlorophyll was incomplete unless biofilms were fully hydrated. This factor was highly significant for all the solvents tested, with at least three times more pigment being extracted from hydrated samples than from dry ones. Methanol was the most efficient solvent, releasing over 96% of the total chlorophyll during a single extraction; hot ethanol extracted 86%, while acetone extracted less than 50%. Sonicating samples during extraction did not release any additional pigment. Centrifuging to remove suspended material did not alter estimates and was not advantageous. Rugose rock surfaces released more chlorophyll than smooth ones. However, a simple method to quantify surface rugosity at an appropriate scale was not available.

Based on these observations, a standard method for chlorophyll extractions from epilithic biofilms using 100% methanol at room temperature (20°C) is proposed. This technique requires considerably less supervision than previously preferred methods and gave a chlorophyll extract which was stable for 15 h.
Exceptional influx of oceanic species into the North Sea late 1997
Authors: Edwards M. , John A.W.G. , Hunt H.G. , Lindley J.A.
Published: July 2002

Continuous Plankton Recorder records from the North Sea and north-east Atlantic from September 1997 to March 1998 indicate an exceptional influx of oceanic indicator species into the North Sea. These inflow events, according to historical evidence, have only occurred sporadically during this century. This exceptional inflow and previous inflow events are discussed in relation to their similarity in terms of their physical and climatic conditions.
James Brooke and the Bidayuh: Some Ritual Dimensions of Dependency and Resistance in Nineteenth-Century Sarawak
Authors: WALKER J. H.
Published: July 2002

The relations between James Brooke and the various peoples of northwest Borneo have attracted considerable scholarly attention. Nineteenth-century Iban experiences have been analysed extensively and continue to provide the basis for a healthy industry in historical anthropology. Daniel Chew and Craig Lockard examined the development of the Sarawak Chinese community. Sabihah Osman explored Malay political activity during the Brooke period. In contrast, although Bidayuh were the subject of a detailed anthropological survey in the 1950s, political relations between Bidayuh and Rajah Brooke's regime have been largely ignored by scholars.
DER ERSTE APOKALYPTISCHE REITER UND DER KÖNIG DER KÖNIGE. EIN BEITRAG ZUR CHRISTOLOGIE DER JOHANNESAPOKALYPSE
Authors: HERZER JENS
Published: July 2002

In der Forschung zur Johannesapokalypse ist die Deutung des ersten apokalyptischen Reiters (Apk 6.2) kontrovers. Neben die verbreitete negative Deutung traten in den letzten Jahren verschiedene Ansätze für ein positives christologisches Verständnis. In Auseinandersetzung damit wird ein bisher nicht berücksichtigtes Problem besonders in den Blick genommen, daß nämlich der erste Reiter einerseits positiv interpretiert werden kann, dann aber andererseits als ein Siegel am siebenfach versiegelten Buch zu deuten ist, das nicht als Buch des Gerichtes, sondern als Lebensbuch des Lammes verstanden werden muß. Schließlich wird seine konzeptuelle Bedeutung im Zusammenhang mit dem Reiter von Apk 19 beschrieben.
Praziquantel-induced tegumental damage in vitro is diminished in schistosomes derived from praziquantel-resistant infections
Authors: WILLIAM S. , BOTROS S. , ISMAIL M. , FARGHALLY A. , DAY T.A. , BENNETT J.L.
Published: July 2002

The aggressive use of praziquantel to combat schistosomiasis in Egpyt raises concern about the possible emergence of resistance. Eggs from Egyptian patients with praziquantel-resistant infections (not cured by 3 doses of praziquantel) have been used to establish infection-specific schistosome isolates in mice. The response of these worms to the drug was observed in vitro, in order to determine if the isolates obtained from these resistant infections were, in fact, less responsive to praziquantel. One of the hallmark effects of praziquantel on schistosomes in vitro is a disruption of the worm's outer surface, the tegument. Here, praziquantel-induced tegumental damage is observed in 3 distinct isolates, 2 derived from resistant infections and 1 from an infection cured by a single dose. The isolates from the resistant infections were less susceptible to praziquantel-induced tegumental damage in vitro, suggesting that the worms are in some way less responsive to the drug.
Genetic typing and phylogeny of the Leishmania donovani complex by restriction analysis of PCR amplified gp63 intergenic regions
Authors: MAURICIO I. L. , GAUNT M. W. , STOTHARD J. R. , MILES M. A.
Published: July 2002

Protozoan parasites of the Leishmania donovani complex (L. donovani, L. infantum/L. chagasi) are causative agents of visceral leishmaniasis. To understand phylogeny and taxonomy within this group better we have developed 2 new polymerase chain reaction-linked restriction fragment length polymorphism (PCR–RFLP) analyses of the major surface protease (msp or gp63) intergenic (ITG) regions. We have named this approach msp intergenic region RFLP typing (MIRT). One intergenic region lies between the constitutive msp (mspC) and stationary phase msp (mspS4) genes (ITG/CS) and the other between multicopy logarithmic phase msp (mspL) genes (ITG/L). The markers generated robust and congruent phylogenies, identifying 5 genetic clusters within L. donovani. One cluster was synonymous with L. infantum (L. chagasi); clusters strongly correlated with isoenzyme typing and some with geographical origin. These genetic groups may be important for epidemiological and clinical studies. The congruence of the groups identified indicates suitability of these genomic targets for taxonomic studies. Furthermore, subgroups of L. donovani were of equivalent phylogenetic status to L. infantum. No evidence was found to support the existence of L. archibaldi. It is likely to be necessary in future to re-evaluate the taxonomic status of L. donovani or of L. infantum, as discrete species.
Phylogenetic relationships of three hymenolepidid species

inferred from nuclear ribosomal and mitochondrial DNA sequences
Authors: OKAMOTO M. , AGATSUMA T. , KUROSAWA T. , ITO A.
Published: July 2002

Three hymenolepidid tapeworms, Hymenolepis diminuta, H.
nana

and H. microstoma, are commonly maintained in

laboratory rodents and used in many experimental model systems of

tapeworm infections. We examined partial sequences

from the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene

and nuclear ribosomal internal transcribed spacer 2

(ITS2) sequences to infer phylogenetic relationships of the 3 hymenolepidid

species. Parts of the CO1 gene and ITS2 were

amplified by PCR and sequenced directly. The CO1 gene sequence obtained

was the same in length (391 bp) among all

specimens. In the case of ITS2, however, several insertions and deletions

were detected (671–741 bp) not only among

species but also between an American isolate and a Japanese isolate of

H. diminuta. Percentage nucleotide differences

between H. diminuta and H. microstoma, or H. diminuta

and H. nana were 16·6–18·2% for the CO1 gene
and

21·3–22·9%

for ITS2. The differences in both sequences between H. microstoma
and

H. nana were about 14%. Phylogenetic trees

inferred from both of the nucleotide sequences showed similar topology,

and suggest that H. diminuta may have diverged

from the common ancestral line the earliest, and that H.

nana is closer to H. microstoma than to H. diminuta.
Acidic compartments and rhoptry formation in Toxoplasma gondii
Authors: SHAW M. K. , ROOS D. S. , TILNEY L. G.
Published: July 2002

DAMP (3-(2,4-dinitroanilino)-3′amino-N-methyldipropylamine),
which differentially accumulates in acidic compartments, was used to identify
such compartments in Toxoplasma gondii tachyzoites at the electron
microscope level. In both
free tachyzoites and dividing intracellular parasites the only sites of
DAMP accumulation were mature and forming
rhoptries. No labelling of other secretory organelles (micronemes and dense
granules), the ER, Golgi or any other
membrane-bounded organelles or anything resembling a lysosomal system was
observed. Labelling of the forming
rhoptries was higher and more homogenous than in mature rhoptries in which
labelling was confined to the expanded ends
of each organelle. The acid pH-dependent accumulation of DAMP in the forming
and mature rhoptries was blocked by
ammonium chloride and monensin, reagents known to abolish intracellular
pH gradients. Estimates of rhoptry pH, based
on the level of DAMP accumulation, show that the intralumenal pH of forming
rhoptries is more acidic (pH 5·5–3·5) than
the mature rhoptries (pH 7·0–5·0).
Characterization of experimental Cryptosporidium parvum
infection in IFN-γ knockout mice
Authors: YOU XIANGDONG , MEAD J. R.
Published: July 2002

Severe cryptosporidial infections were produced in gamma interferon
(IFN-γ) knockout mice. Mean oocyst shedding
increased from 332 to 30717 oocysts/100 μl of faecal suspension
between day 4 and 9 after administration of 1×105
oocysts/mouse. No significant differences in oocyst shedding were observed
in mice after being inoculated with 1×105, 1×104
or
1×103
oocysts/mouse (P>0·05). Infected mouse weights decreased
an average 3–4 g before death or
euthanization. Histological studies revealed heavy parasite colonization
in small intestinal epithelium (approximately
250 organisms/high-power field at ×400). Mesenteric lymph nodes
in infected mice were markedly enlarged compared
to controls (P<0·05). Both CD4+ and CD8+

T cell populations increased in spleens of infected mice while the B cell

population increased in mesenteric lymph nodes from infected mice. No significant
proliferation was observed when
pooled lymphocytes from infected mice were exposed to C. parvum
antigens in vitro. Addition of recombinant mouse
IFN-γ did not restore antigen responsiveness. While lymphoproliferative
responses to specific antigen were not significant
in the short period following infection, this mouse model provides unique
features to study the characteristics of acute
infection and the immune response against C. parvum.
The development of murine cerebral malaria does not
require nitric oxide production
Authors: FAVRE N. , RYFFEL B. , RUDIN W.
Published: July 2002

Nitric oxide (NO) production has been suggested to be required
for the development of cerebral malaria. However, the
importance of this molecule for the appearance of this pathology is debated.
To assess whether murine cerebral malaria
is NO dependent, we investigated the course of blood-stage Plasmodium
berghei ANKA (PbA) infections in inducible nitric
oxide synthase (iNOS)-deficient mice. Parasitaemia, haematological alterations,
survival and development of cerebral
malaria were not affected by the lack of iNOS. To exclude a role of NO
produced by other NOS, controls included NO
suppression by oral administration of aminoguanidine (AG), a NOS inhibitor.
As in iNOS-deficient mice, no difference
in the parasitaemia course, survival and haematological values was observed
after AG treatment. Our results indicate that
NO production is not a crucial factor for the development of murine cerebral
malaria.
Aqueous aluminium eliminates Gyrodactylus salaris
(Platyhelminthes, Monogenea) infections in
Atlantic salmon
Authors: SOLENG A. , POLÉO A. B. S. , ALSTAD N. E. W. , BAKKE T. A.
Published: July 2002

This study focuses on the effect of acidic water and aqueous aluminium on the monogenean ectoparasite Gyrodactylus
salaris, infecting Atlantic salmon (Salmo salar) parr. G. salaris-infected salmon were exposed to various combinations of
acidity and aluminium concentrations. The most pronounced effect was the elimination of parasites after 4 days when
202 μg Al/l was added to the water. The effect of aluminium was concentration dependent, but was relatively independent
of pH (5·2, 5·6 and 5·9). At the lowest pH of 5·0 the effect of aluminium was enhanced. Acidic aluminium-poor water had
no or minor effects on the G. salaris infections except at pH 5·0 where all parasites were eliminated within 9 days. The
G. salaris populations increased exponentially in untreated control water. The results show for the first time that aqueous
aluminium can, to a limited extent, have a positive effect on fish health. This study emphasizes that basic knowledge about
abiotic environmental factors is of importance in order to understand the population dynamics, range extension and
dispersal of ectoparasites such as G. salaris. Finally, our results suggest that aluminium treatment could form an effective
disinfection method against ectoparasites in hatcheries and laboratories, as well as complementing the controversial
rotenone treatments used against natural populations of G. salaris.
Cloning and characterization of a β-galactoside-binding
protein (galectin) from the gut of the gastrointestinal
nematode parasite Haemonchus contortus
Authors: NEWLANDS G. F. J. , SKUCE P. J. , KNOX D. P. , SMITH S. K. , SMITH W. D.
Published: July 2002

A cDNA encoding a β-galactoside-binding lectin (galectin) was identified by immunoscreening a Haemonchus contortus
cDNA library with antisera from lambs vaccinated with a membrane protein complex (H-gal-GP) derived from the
parasites' gut. The cDNA sequence, exhibiting a tandem repeat structure and designated Hco-gal-2, showed significant
levels of similarity with galectins from several species of nematode as well as mammalian galectin type 4. Native galectin
was preferentially extracted from the H-gal-GP complex and also from an insoluble membrane fraction prepared from
adult worms using lactose–agarose affinity chromatography. The affinity-purified material had apparent molecular mass
of around 35 kDa with 3 distinct bands visible on SDS–PAGE. All 3 bands were identified as galectins by reaction with
antiserum raised to recombinant Hco-GAL-2 on Western blot. To determine whether H. contortus galectins have any
protective capacity against infection lambs were vaccinated with affinity-purified galectin and subsequently given a single
challenge infection. Vaccination did not confer any protection against infection with H. contortus as judged by faecal egg
output or worm counts.
Is Time a Continuum of Instants?
Authors: Dummett Michael
Published: July 2002

Our model of time is the classical continuum of real numbers, and our model of other measurable quantities that change over time is that of functions defined on real numbers with real numbers as values. This model is not derived from reality or from our experience of it, but imposed on reality; and the fit is very imperfect. In classical mathematics, the value of a function for any real number as argument is independent of its value for any other argument: the analogue is Hume's doctrine that events are loose and separate. This makes continuity in the change of any quantity a contingent law of physica, rather than a conceptual necessity. The article explores alternatives to this classical model.
Moral Sentiments, Social Exclusion, Aesthetic Education
Authors: McGhee Michael
Published: July 2002

There is a dichotomy in the Humean thought that morality is more properly felt than judged of. The idea of a moral sensibility with an epistemic and rational content is grounded in the experience of the state of nature, and a distinction made between a defensive and a constructive morality, constituted by a set of motivations, against the law of the strongest, and protective of the relationships of education and creative work, exclusion from which undermines the conditions for a constructive morality. Aesthetic education is a means of overcoming the sectarianism of defensive morality.
Effects of olanzapine on cerebellar functional connectivity in schizophrenia measured by fMRI during a simple motor task
Authors: STEPHAN K. E. , MAGNOTTA V. A. , WHITE T. , ARNDT S. , FLAUM M. , O'LEARY D. S. , ANDREASEN N. C.
Published: July 2002

Background. According to current theories, schizophrenia results from altered connectivity in brain circuits for fundamental cognitive operations. Consequently, the poorly understood mechanisms of neuroleptic treatment may be explainable by altered functional interactions within such networks. The ‘cognitive dysmetria’ model hypothesizes that one key structure in these circuits is the cerebellum. To investigate the effects of olanzapine on cerebellar functional connectivity (CFC), a seed-voxel correlation analysis (SVCA) was used in a functional magnetic resonance imaging (fMRI) study of a simple finger-tapping task.

Methods. fMRI scans were obtained from six schizophrenic patients under both drug-free and olanzapine-treated conditions and from a matched control group of six healthy subjects at corresponding time points. SVCAs were performed for anatomically and functionally standardized seed voxels in the anterior cerebellum. SVCA results were then processed by three different randomization analyses.

Results. The analyses revealed that olanzapine caused widespread changes of CFC, including prominent changes in prefrontal cortex and mediodorsal thalamus. Significant changes in motor structures were found after subtractions within both groups and may thus indicate repetition effects rather than drug effects. Olanzapine ‘normalized’ the patients' CFC patterns for the right, but not for the left cerebellum.

Conclusion. Even for a simple motor task, olanzapine affects functional interactions between the cerebellum and many non-motor brain regions, including elements of the ‘cognitive dysmetria’ circuit. Altogether, our findings suggest that olanzapine has a stronger differential effect on neural activity in prefrontal cortex and thalamus than in motor structures.
A twin study of mortality after spousal bereavement
Authors: LICHTENSTEIN P. , GATZ M. , BERG S.
Published: July 2002

Background. Previous research has shown an increased risk

of mortality after spousal bereavement,
with the highest risk in the first weeks or months closest to the loss.

One difficult issue in these
designs is appropriate covariates and control groups.

Method. This study is based on 1993 pairs of twins discordant

for marital status and on 35860
married individuals from the Swedish Twin Registry born between 1886 and
1958 and followed for
marital and vital status between 1981 and 1993.

Results. Spousal bereavement was a risk factor for mortality

for both men and women using the
still married co-twin as a control to the widowed proband, and
controlling for earlier health status
and health-related risk factors. The mortality risk was higher for young-old
(under 70 years)
individuals, and for recently widowed than for longer-term widowed. Young-old
women had a
pattern with increased mortality risk during the first years
after bereavement, but also a markedly
decreased risk if they survived 4 years after bereavement, as compared
to married women.

Conclusions. The results support a causal effect of bereavement

on mortality. The decrease in risk
for long-term young-old women is congruent with reports by widows of psychological
growth after
bereavement, involving increased sense of mastery and competence
after learning to live in new sets
of circumstances following the loss of their husband.
Attention deficit hyperactivity disorder in adults
Authors: SACHDEV PERMINDER
Published: July 2002

Adults with putative attention deficit hyperactivity disorder (ADHD) are increasingly being
referred to psychiatric clinics, often following a self-diagnosis, and demanding a prescription
for stimulant medication. This has disconcerted many clinicians and started a debate on the
appropriateness of this diagnosis in adults (Shaffer, 1994; Lomas, 1995; Diller, 1996) that is
reminiscent of the controversies of the childhood diagnosis in previous years (Lancet, 1986). At
issue is not only concern about the widespread use of stimulant medication, but also a
neurobiological understanding of impulsivity, hyperactivity and antisocial behaviour and the
genesis of some psychiatric disorders in adults. How is the validity of this disorder in adults then
to be established?
Early sexual abuse and lifetime psychopathology:
a co-twin–control study
Authors: DINWIDDIE S. , HEATH A. C. , DUNNE M. P. , BUCHOLZ K. K. , MADDEN P. A. F. , SLUTSKE W. S. , BIERUT L. J. , STATHAM D. B. , MARTIN N. G.
Published: July 2002

Background. This study was designed to determine lifetime prevalence of psychiatric disorders
among twins who reported childhood sexual abuse (CSA), and to compare these rates with those
among non-abused co-twins. The contribution of familial and individual-specific factors to reported
sexual abuse was also examined.

Method. Information about lifetime psychopathology and substance use was obtained by structured
telephone interviews with 5995 Australian twins. Twins who reported a history of childhood sexual
abuse (CSA) were contrasted on lifetime psychopathology with subjects without such a history; in
addition, comparisons were made between same-sex twin pairs discordant for CSA.

Results. A history of CSA was reported by 5·9% of the women and 2·5% of the men. In the sample
as a whole, those reporting CSA were more likely to receive lifetime diagnoses of major depression,
conduct disorder, panic disorder and alcoholism, and were more likely to report suicidal ideation
and a history of suicide attempt. Abused women, but not men, were also more likely to report social
phobia. When comparisons were restricted to non-abused co-twins, no differences in
psychopathology were seen. However, rates of major depression, conduct disorder and suicidal
ideation were higher if both co-twins were abused than if the respondent alone reported CSA.
Model-fitting indicated that shared environmental factors influenced risk for reported CSA in
women, but not in men.

Conclusion. The association between CSA and psychopathology arises at least in part through the
influence of shared familial factors on both risk of victimization and risk of psychopathology.
A neuropsychological comparison of schizophrenia
and schizophrenia-like psychosis of epilepsy
Authors: MELLERS J. D. C. , TOONE B. K. , LISHMAN W. A.
Published: July 2002

Background. The schizophrenia-like psychoses of epilepsy (SLPE) might represent a secondary
form of schizophrenia in which the pathology is relatively confined to the temporal lobe. To test this
possibility we have compared the neuropsychological profile of schizophrenia and SLPE. Our main
hypothesis was that both psychotic groups would show deficits of temporal lobe function but that
prefrontal impairment, as measured by tests of executive function, would be found only in the
primary schizophrenic group.

Methods. Four groups were studied: (1) patients with SLPE (N = 25); (2) patients with epilepsy but
not psychiatric history (N = 24); (3) patients with schizophrenia (N = 22); and (4) healthy
volunteers (N = 24). Neuropsychological testing comprised measures of pre-morbid IQ, current
verbal and performance IQ, information processing, digit span, motor speed, verbal and visual
learning and memory, verbal fluency, the Wisconsin Card Sorting Task, the Stroop test and the trail
making task.

Results. Patients with schizophrenia and those with SLPE had almost identical neuropsychological
profiles, with impairments of attention, episodic memory (verbal > visual) and executive function.
The epileptic controls showed similar though less severe impairments of memory and of some tests
of executive function.

Conclusions. Our results do not support the hypothesis that the pathophysiology of SLPE and
schizophrenia are distinct. While our findings suggest an important role for dominant temporal lobe
abnormality in schizophrenia, both in its primary form and in that occurring in patients with
epilepsy, they also implicate generalized cognitive impairment, manifest in particular as attentional
deficits, in both forms of the disorder.