bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of pressure gradients on turbulent premixed flames
Authors: VEYNANTE DENIS , POINSOT THIERRY
Published: July 2002

In most practical situations, turbulent premixed flames are

ducted and, accordingly,

subjected to externally imposed pressure gradients. These pressure gradients
may

induce strong modifications of the turbulent flame structure because of
buoyancy

effects between heavy cold fresh and light hot burnt gases. In the present
work, the

influence of a constant acceleration, inducing large

pressure gradients, on a premixed

turbulent flame is studied using direct numerical simulations.

A favourable pressure gradient, i.e. a pressure decrease from unburnt
to burnt

gases, is found to decrease the flame wrinkling, the flame brush thickness,
and the

turbulent flame speed. It also promotes counter-gradient turbulent transport.
On the

other hand, adverse pressure gradients tend to increase the flame brush
thickness

and turbulent flame speed, and promote classical gradient turbulent transport.
As

proposed by Libby (1989), the turbulent flame speed is modified by a buoyancy
term

linearly dependent on both the imposed pressure gradient and the integral
length

scale lt.

A simple model for the turbulent flux

u″c″ is also proposed, validated from

simulation data and compared to existing models. It is shown that turbulent

premixed flames

can exhibit both gradient and counter-gradient transport and a criterion
integrating

the effects of pressure gradients is derived to differentiate

between these regimes. In

fact, counter-gradient diffusion may occur in most practical ducted flames.
Oscillations and breakup of a bubble immersed in a turbulent field
Authors: RISSO FRÉDÉRIC , FABRE JEAN
Published: July 2002

This work is an experimental study of the deformation and breakup
of a bubble in a
turbulent flow. A special facility was designed to obtain intense turbulence
without
significant mean flow. The experiments were performed under microgravity
conditions
to ensure that turbulence was the only cause of bubble deformation. A scalar

parameter, characteristic of this deformation, was obtained by video processing
of
high-speed movies. The time evolution and spectral representation of this
scalar
parameter showed the dynamical characteristics of bubble deformation. The
signatures
of the eigenmodes of oscillation predicted by the linear theory were clearly
observed
and the predominance of the second mode was proved. In addition, numerical

simulations were performed by computing the response of a damped oscillator
to the
measured turbulence forcing. Simulations and experiments were found to
be in good
agreement both qualitatively, from visual inspections of the signals, and
quantitatively,
from a statistical analysis. The role of bubble dynamics in the deformation
process has
been clarified. On the one hand, the time response of the bubble controls
the maximum
amount of energy which can be extracted from each turbulent eddy. On the
other hand,
the viscous damping limits the energy that the bubble can accumulate during
its
fluctuating deformation. Moreover, two breakup mechanisms have been identified.

One mechanism results from the balance between two opposing dominant forces,
and
the other from a resonance oscillation. A new parameter, the mean efficiency

coefficient, has been introduced to take into account the various aspects
of bubble
dynamics. Used together with the Weber number, this parameter allows the
prediction
of the occurrence of these two mechanisms. Finally, the influence of the
residence time
of the bubble on the statistics of the deformation has been analysed and
quantified.
The multi-dimensional stability of
weak-heat-release detonations
Authors: SHORT MARK , STEWART D. SCOTT
Published: July 2002

The stability of an overdriven planar detonation wave is examined
for a one-step
Arrhenius reaction model with an order-one post-shock temperature-scaled
activation
energy θ in the limit of a small post-shock temperature-scaled
heat release β. The ratio of specific heats, γ is taken such
that
(γ−1)=O(1). Under these assumptions, which cover a
wide range of
realistic physical situations, the steady detonation structure can be evaluated
explicitly,
with the reactant mass fraction described by an exponentially
decaying function. The analytical representation of the steady structure
allows a
normal-mode description of the stability behaviour to be obtained via a
two-term
asymptotic expansion in β. The resulting dispersion relation predicts
that for a finite
overdrive f, the detonation is always stable to
two-dimensional disturbances. For large
overdrives, the identification of regimes of stability or instability is
found to depend
on a choice of distinguished limit between the heat release β and
the detonation
propagation Mach number D*. Regimes of instability
are found to be characterized by
the presence of a single unstable oscillatory mode over a finite range
of wavenumbers.
Laminar free convection induced by a line heat
source, and heat transfer from wires at small Grashof numbers
Authors: LIÑÁN AMABLE , KURDYUMOV VADIM N.
Published: July 2002

The buoyancy-induced laminar flow and temperature fields associated
with a line
source of heat in an unbounded environment are described by numerically
solving
the non-dimensional Boussinesq equations with the appropriate boundary
conditions.
The solution is given for values of the Prandtl number, the single parameter,
ranging
from zero to infinity. The far-field form of the solution is well known,
including a
self-similar thermal plume above the source. The analytical description
close to the
source involves constants that must be evaluated with the numerical solution.

These constants are used when calculating the free convection heat transfer
from
wires (or cylinders of non-circular shape) at small Grashof numbers. We
find two
regions in the flow field: an inner region, scaled with the radius of the
wire, where
the effects of convection can be neglected in first approximation, and
an outer
region where, also in first approximation, the flow and temperature fields
are those
due to a line source of heat. The cases of large and small Prandtl numbers
are
considered separately. There is good agreement between the Nusselt numbers
given
by the asymptotic analysis and by the numerical analysis, which we carry
out for
a wide range of Grashof numbers, extending to very small values the range
of
existing numerical results; there is also agreement with the existing correlations
of the
experimental results. A correlation expression is proposed for the relation
between
the Nusselt and Grashof numbers, based on the asymptotic forms of the relation
for
small and large Grashof numbers.
A uniformly valid analytic solution of

two-dimensional viscous flow over a semi-infinite

flat plate
Authors: LIAO SHI-JUN
Published: July 2002

We apply a new kind of analytic technique, namely the homotopy analysis method

(HAM), to give an explicit, totally analytic, uniformly valid solution of the two-dimensional laminar viscous flow over a semi-infinite flat plate governed by

f‴(η)+αf(η)f″(η)+β[1−f′2(η)]=0 under the boundary

conditions f(0)=f′(0)=0, f′(+∞)=1. This analytic

solution is uniformly valid in the whole region 0[les ]η<+∞. For Blasius'

(1908) flow (α=1/2, β=0), this solution converges to Howarth's (1938)

numerical result and gives a purely analytic value f″(0)=0.332057. For the

Falkner–Skan (1931) flow (α=1), it gives the same family of solutions as

Hartree's (1937) numerical results and a related analytic formula for

f″(0) when 2[ges ]β[ges ]0. Also, this analytic solution proves that when

−0.1988[les ]β0 Hartree's (1937) family of solutions indeed possess the

property that f′→1 exponentially as η→+∞. This verifies

the validity of the homotopy analysis method and shows the potential possibility of applying

it to some unsolved viscous flow problems in fluid mechanics.
Particle-driven gravity currents down planar slopes
Authors: BONNECAZE ROGER T. , LISTER JOHN R.
Published: July 2002

Particle-driven gravity currents, as exemplified by either turbidity currents in the ocean
or ignimbrite flows in the atmosphere, are buoyancy-driven flows due to a suspension
of dense particles in an ambient fluid. We present a theoretical study on the dynamics
of and deposition from a turbulent current flowing down a uniform planar slope from
a constant-flux point source of particle-laden fluid. The flow is modelled using the
shallow-water equations, including the effects of bottom friction and entrainment of
ambient fluid, coupled to an equation for the transport and settling of the particles.
Two flow regimes are identified. Near the source and for mild slopes, the flow is
dominated by a balance between buoyancy and bottom friction. Further downstream
and for steeper slopes, entrainment also affects the behaviour of the current. Similarity
solutions are also developed for the simple cases of homogeneous gravity currents
with no settling of particles in the friction-dominated and entrainment-dominated
regimes. Estimates of the width and length of the deposit from a monodisperse
particle-driven gravity current with settling are derived from scaling analysis for each
regime, and the contours of the depositional patterns are determined from numerical
solution of the governing equations.
Nonlinear stability of a stratified shear flow in
the regime with an unsteady critical layer. Part 2.
Arbitrary stratification of asymmetric flow
Authors: CHURILOV S. M.
Published: July 2002

A weakly nonlinear analysis of the downstream evolution of weakly unstable disturbances
in a stably stratified mixing layer with a large Reynolds number is carried out.
No other requirements are imposed upon velocity and density profiles, thus making
it possible to overcome the restrictions placed in earlier studies (Brown & Stewartson
1978; Brown et al. 1981; Churilov & Shukhman 1987, 1988) by a particular choice
of weakly supercritical flow models assuming symmetry. For each of the two critical
layer regimes possible here, viscous and unsteady, evolution equations are obtained,
their solutions and competition between nonlinearities in the course of instability
development are analysed, and evolution scenarios for unstable disturbances are constructed
for different levels of their supercriticality. It is established that the regime
with a nonlinear critical layer does not arise in an evolutionary manner, except for
the previously studied case of a weak stratification (Shukhman & Churilov 1997). It
is shown that while in the viscous critical layer regime the relaxation of assumptions
of the symmetry and weak supercriticality of the flow produces no fundamental
changes in the theory, in the unsteady critical layer regime a new (non-dissipative
cubic) nonlinearity appears which governs the instability development on equal terms
with two already known nonlinearities. Results are illustrated by calculations for two
families of flow models with a controlled degree of asymmetry.
Enemies Evermore: US Policy Towards Cuba After Helms-Burton
Authors: LEOGRANDE WILLIAM M.
Published: July 2002

When Cuban MiGs blasted two civilian planes out of the sky

over the Straits of Florida on February 24 1996, they also destroyed

any chance of improved relations between Cuba and the United States as

long as Fidel Castro remains in power. In Washington, outrage over the

shoot-down resurrected the Helms-Burton bill, the most punitive

legislation on Cuba since the early 1960s. On 12 March, President Bill

Clinton signed the bill into law as the Cuban Liberty and Democratic

Solidarity Act of 1996. In addition to assorted sanctions aimed at

foreigners doing business in Cuba, the most consequential provision

incorporates the US economic embargo into law. Heretofore, the embargo

was based on presidential executive orders; it could be tightened or

loosened at the president's discretion as conditions warranted.

Under Helms-Burton, no president can lift or even relax the embargo

until Fidel Castro and the existing Cuban regime fall from power. At a

time when Cuba's domestic social and economic system is changing

at break-neck speed, Washington's 35-year-old policy of hostility

has just been chiselled in stone.
HF surface cyclotron waves in planar waveguide structures
with non-uniform plasma filling
Authors: GIRKA V. O. , GIRKA I. O. , PAVLENKO I. V.
Published: July 2002

The effects of dispersion of slow electromagnetic surface waves
propagating
across an external magnetic field in planar metallic waveguides with dielectric
coating and non-uniform plasma filling on the harmonics of the electron
cyclotron frequency are studied. The theoretical investigation of the surface
modes is carried out using a kinetic description for the plasma particles
and a
mirror-reflection model for the interaction between particles and plasma
boundary. The effect of the transverse plasma density inhomogeneity on
the
electron surface cyclotron-wave spectrum is investigated.
The double sheath associated with electron emission into a plasma

containing negative ions
Authors: AMEMIYA H. , ANNARATONE B. M. , ALLEN J. E.
Published: July 2002

The double sheath formed by thermal electrons and negative ions
in a plasma
and electrons emitted from an electrode is investigated. The ion energy
at the
sheath edge and the electric field at the electrode surface are calculated
for
several values of the ratio of negative-ion density to electron density.
The
maximum beam density above which a virtual cathode appears is given. The

relation to the Langmuir limit is shown. The numerical results for the
electric
potential, the electric field and the space charge density are presented.
The
floating potential is calculated from the current balance of all components.
Structure of small-amplitude quasiparallel
magnetohydrodynamic shock waves in
plasmas with anisotropic viscosity and
thermal conductivity
Authors: RUDERMAN M. S.
Published: July 2002

Shock waves in plasmas with strongly anisotropic viscosity and
thermal conductivity
are considered. The analysis is restricted to the case where the plasma
beta
is less than unity. The set of two equations that governs propagation of
small-amplitude
MHD waves at small angles with respect to the unperturbed magnetic
field in such plasmas is derived. A qualitative analysis of this set of
equations is
carried out. It is shown that the shock structure is described by a solution
that
is a separatrix connecting two stationary points: a stable node and a saddle.
This
solution describes the structure of a fast quasiparallel shock wave, and
it only exists
when the ratio of the magnetic field component, perpendicular to the direction
of
shock-wave propagation after and before the shock is smaller than a critical
value.
This critical value is a function of the plasma beta. The structures of
shock waves
are calculated numerically for different values of the shock amplitude
and the ratio
of the coefficients of viscosity and thermal conductivity.
Growth anomalies in Pecten maximus from coastal waters (Bay of Brest, France): relationship with diatom blooms
Authors: Lorrain Anne , Paulet Yves-Marie , Chauvaud Laurent , Savoye Nicolas , Nézan Elisabeth , Guérin Laurent
Published: July 2002

The aim of this study was to characterize the daily shell growth of Pecten maximus from early 1998 to late spring 1999 in the Bay of Brest with a careful qualitative and quantitative description of the pelagic primary production. Our results, in accordance with previous studies, demonstrate that there are episodic declines in the growth rate. Concurrent events of low growth rate and large bottom-concentrations of algae following diatom blooms (Cerataulina pelagica or Rhizosolenia delicatula), suggests that this high concentration of phytoplankton on the bottom layer may affect food intake or respiratory activity of the scallops by gill clogging or oxygen depletion. In this study, silicic acid or phosphorus are inferred to be limiting factors responsible for the collapse of the spring bloom. Further, we suggest that, in an N-enriched ecosystem, Si or P-limitation and the changing sinking velocities of phytoplankton, could affect the biology of benthic suspension-feeders.
Comparison of stable carbon and nitrogen isotope signatures of the polychaete Nereis diversicolor from different estuarine sites
Authors: Nithart Mathilde
Published: July 2002

The natural abundance of stable carbon and nitrogen isotope ratios for Nereis diversicolor (Annelida: Polychaeta) from 16 sites around the UK are analysed. Differences in the isotopic compositions reflect variations either in the dietary origin or in the estuary characteristics. In contrast to Stiffkey Nereis, the ones from the other estuaries are characterized by broad δ13C (−13.9 to −22.6‰) and δ15N (+11.3 to +17.9‰) ranges. An hypothesis based on sediment denitrification is discussed to explain the anomalously heavy δ15N compositions of Nereis from the Humber Estuary (+16.9 to +18.1‰) and Breydon Water (+17.7±0.5‰).
The effect of trematode parthenitae on the growth of Onoba aculeus, Littorina saxatilis and L. obtusata (Gastropoda: Prosobranchia)
Authors: Gorbushin A.M. , Levakin I.A.
Published: July 2002

To determine whether modern theories predict snail growth responses to trematode infestation a field growth study of Onoba aculeus, Littorina saxatilis and L. obtusata infected with two closely related Microphallidae trematodes was conducted in the White Sea. In each of the three host–parasite combinations studied trematode infection causes inhibition of snail reproduction. However, contrary to the classical interpretation of the gigantic growth of infected snails as a side effect of parasitic castration, the presented study failed to demonstrate that Microphallus piriformes causes gigantism in Littorina. The infection tended to stunt growth in L. obtusata and had no significant effect on growth rate of L. saxatilis. In contrast, gigantic growth was observed in O. aculeus infected with M. pseudopygmaeus. Considering that both trematode species are very similar biologically, the discrepancy is attributed to differences in the life history of the snail's hosts. Onoba aculeus is a relatively short-lived snail (2.5–3 y). The lifespan of L. saxatilis and L. obtusata is much longer (up to 9–11 y). These findings agree with a previously reported ‘energetic’ hypothesis that predicts growth alterations in accordance with life history variations of the snail species.
Species identification of bivalve larvae using random amplified polymorphic DNA (RAPD): differentiation between Cerastoderma edule and C. lamarcki
Authors: André C. , Lindegarth M. , Jonsson P.R. , Sundberg P.
Published: July 2002

The polymerase chain reaction (PCR) was used to produce species-specific DNA markers (RAPDs) from two sibling cockle species and five other co-occurring intertidal bivalves. Amplification reactions with one single primer readily distinguished larvae and adults of Cerastoderma edule from larvae and adults of C. lamarcki, and from adults of Mya arenaria, Macoma balthica, Scrobicularia plana, Venerupis pulastra and Mytilus edulis. Random amplified polymorphic DNA (RAPD) is suggested as a simple and quick method to determine species identity in taxa that are difficult to identify on the basis of morphological characters alone, such as marine bivalve larvae.
Functional morphology and taxonomic relevance of the female genital structures in Acartiidae (Copepoda: Calanoida)
Authors: Barthélémy R.-M.
Published: July 2002

Observations of female genital structures using light and scanning electron microscopy in 25 species of Acartiidae (Copepoda: Calanoida) show the presence of paired gonopores and egg-laying ducts with a typical semicircular configuration in all specimens. In the genus Acartiella, there is no seminal receptacle and the external genital area serves as storage site of the spermatophoral products forming an external mass. Unlike in the other acartiids, the genital structures present a complex organization with paired adjacent gonopores and copulatory pores. In almost all the species, the seminal receptacles exhibit characteristic loop-shaped seminal ducts which connect them to the egg-laying ducts. The functional morphology and taxonomic relevance of genital structures are discussed. The present results do not justify the Steuer's subgenus division of the genus Acartia, the very predominant one of the family.
Morphological study of the gut in Sagitta setosa, S. serratodentata and S. pacifica (Chaetognatha). Functional implications in digestive processes
Authors: Perez Y. , Arnaud J. , Brunet M. , Casanova J.-P. , Mazza J.
Published: July 2002

The study of the digestive epithelium in Sagitta setosa, S. serratodentata, and S. pacifica revealed only a few morphological and cytological differences among the three species. The gut was divided in two main regions. The first is the cephalic region where the epithelium is composed of three distinct cell types (S1, S2, and S3), the ultrastructure of which is probably specialized either for the synthesis of mucosubstances (S1), or enzymes (S3), or both (S2). The second region of the gut extends to the trunk and is mainly composed of the intestine and a short vertical rectum. No intestinal diverticula were observed. The intestinal epithelium displayed two ciliated cell types, anteriorly, a secretory cell type (S4) containing large mucus-like granules, and a second cell type (A) predominated in the posterior part of the intestine. A-cells appear to have two main functions. Although they exhibit secretory granules, they also display typical endocytotic features in their upper half, i.e. coated vesicles, a well-developed tubulo–vesicular network and two distinct types of digestive vacuoles corresponding to an endosome–lysosome-like system. From the distribution and presumed function of the cells, the gut may be divided in two main functional units, i.e. the cephalic and trunk units.
The Car and the Palanquin: Rival Accounts of the 1895 Riot in Kalugumalai, South India
Authors: Good Anthony
Published: July 2002

The 1895 riot at Kalugumalai in the Tirunelveli District of Madras Presidency, South India, pitted the local Nadar community, then newly-converted to Roman Catholicism, against the main Hindu castes of Kalugumalai, particularly those associated with its Hindu temple and the Ettaiyapuram zamindari estate within which the town lay. It was the violent climax to a long-running dispute over the Nadars' right to take processions through the main streets, and one of the bloodiest episodes in a conflict which posed a severe threat to public order throughout South India in the late nineteenth century.
Mark – Interpreter of Paul
Authors: MARCUS JOEL
Published: July 2002

Claiming that Mark is a Paulinist does not require that he agree with Paul about everything, and plausible reasons can be advanced for a later Paulinist wanting to write the story of the earthly Jesus. Martin Werner's assertion that the agreements between Mark and Paul reflect general early Christian viewpoints is not valid with regard to the theology of the cross, which was a controversial Pauline emphasis and a stress that the later Gospels attenuated in editing Mark. Contrary to Werner, Mark and Paul agree in ascribing Jesus' death to a combination of human and demonic opponents.
Microtubules in Plasmodium falciparum merozoites and
their importance for invasion of erythrocytes
Authors: FOWLER R. E. , FOOKES R. E. , LAVIN F. , BANNISTER L. H. , MITCHELL G. H.
Published: July 2002

Plasmodium falciparum merozoites have an array of 2–3
subpellicular microtubules, designated f-MAST. We have
previously shown that colchicine inhibits merozoite invasion of erythrocytes,
indicating a microtubular involvement in
this process. Colchicine inhibition of invasion was reduced by the Taxol®-stabilization
of merozoite microtubules prior
to colchicine exposure. Immunofluorescence assays showed that the number
and length of f-MASTs were reduced in
colchicine-treated merozoites, confirming that microtubules were the target
of colchicine inhibition. The dinitroaniline
drugs, trifluralin and pendimethalin, were shown by immunofluorescence
to depolymerize the f-MAST and both drugs
were inhibitory in invasion assays. These results demonstrate that the
integrity of the f-MAST is important for successful
invasion. Fluorescence imaging demonstrated the alignment of mitochondria
to f-MAST, suggesting that mitochondrial
transport might be perturbed in merozoites with disorganized f-MAST. Depolymerizing
mt in late-stage schizonts did
not affect the allocation of mitochondria to merozoites.
Effects of an Onchocerca-derived cysteine protease
inhibitor on microfilariae in their simuliid vector
Authors: KLÄGER S. L. , HAGEN H.-E. , BRADLEY J. E.
Published: July 2002

A recombinant cysteine protease inhibitor, onchocystatin of the
parasitic nematode Onchocerca volvulus, was tested for its
role in microfilarial development in the simuliid vector. Onchocystatin
was found to be present in female adults and skin
microfilariae of the bovine parasite O. ochengi, the closest relative
of O. volvulus. In addition the inhibitor could be detected
as an excretory–secretory (E–S) product of the microfilariae.
Co-injection of onchocystatin and the O. ochengi microfilariae

into the surrogate vector Simulium ornatum s.l. significantly
enhanced the recovery rates of the parasite within 24 h into
the infection (P>0·001). The findings suggest a possible
role of onchocystatin in the evasion by the parasite of the immune
response of its vector.
Plasmodium berghei development in irradiated
sporozoite-immunized C57BL6 mice
Authors: ZECHINI B. , CORDIER L. , NGONSEU E. , D'ALESSANDRO U. , WERY M. , CHATTERJEE S.
Published: July 2002

The C57BL6 strain of mice is highly susceptible to Plasmodium
berghei sporozoite infections and consequently requires
repeated immunizations with irradiated sporozoites to obtain protective
immunity. After a live sporozoite challenge in the
immunized hosts, hepatic-stage parasites found in the liver after 48 h
are of different sizes – small schizonts corresponding
to blocked forms (derived from irradiated sporozoites), and schizonts of
intermediate size (derived from live sporozoites).
Large schizonts corresponding to mature hepatic forms are found only in
unimmunized but challenged C57BL6 mice.
Using monoclonal and polyclonal antibodies directed to liver-stage parasites,
different patterns of binding reactivity to the
above forms are observed. More than 20% of the irradiated sporozoites transform
into blocked forms after immunization
and persist in the liver. Upon sporozoite challenge in such immunized animals
the rate of transformation of sporozoites
into hepatic parasites is less than 2%. These observations shed light on
the fate of live sporozoite development in irradiated
sporozoite-immunized C57BL6 mice.
Intestinal parasites in swine in the Nordic countries:
multilevel modelling of Ascaris suum infections in relation
to production factors
Authors: ROEPSTORFF A. , NILSSON O. , O'CALLAGHAN C. J. , OKSANEN A. , GJERDE B. , RICHTER S. H. , ORTENBERG E. Ö. , CHRISTENSSON D. , NANSEN P. , ERIKSEN L. , MEDLEY G. F.
Published: July 2002

In Denmark, Finland, Iceland, Norway and Sweden, 413 sow herds were randomly selected for sampling. Faeces from
pigs of 7 age groups/categories were examined for helminth eggs (11233 individual samples), and an accompanying
questionnaire was completed at each visit. In total, 1138 pigs on 230 farms were found to be positive for Ascaris suum.
Considerable differences in the occurrence of A. suum could be observed directly for several of 20 independent variables
at the herd or category level. However, given that univariate analyses may be severely affected by confounding of covariates
resulting in spurious inference, additional multivariate analyses were undertaken. An ordinary logistic regression on
Ascaris positive/negative farms showed that Denmark had the highest frequency of infected herds, while Iceland and
Finland had the lowest frequencies and that herds using ‘late weaning’ and ‘Class 2’ drugs (pyrantel, levamisole) were most
often infected. Because many herds were found to be totally negative for A. suum, mixed hierarchical logistic-normal
regression models (both the penalized quasi-likelihood and the Markov Chain Monte Carlo methods) were developed for
both a full (all herds) and a reduced (the 230 infected herds) data set using either a cut-off of >0 eggs per gram (epg) or
>200 epg to counter for false-positive egg counts. Estimates for identical models, but where the animal level variance was
constrained to the binomial assumption, were also calculated. Significant covariates were robust to model development
with ‘Age group’, ‘Country’, ‘Weaning age’, ‘Water system’ and simple interactions between the latter two and ‘Age
group’ being significantly associated with the occurrence of A. suum, while all variables concerning anthelmintic drug,
anthelmintic strategy, floor type, bedding, dung removal, washing and disinfection were not. These findings are discussed
in the light of the complex relationship between A. suum and its pig host.
Muscles or testes? Comparative evidence for sexual
competition among dioecious blood parasites
(Schistosomatidae) of vertebrates
Authors: MORAND S. , MÜLLER-GRAF C. D. M.
Published: July 2002

Schistosomes, which live as parasitic adults in the blood vessels of mammals, birds and crocodiles, are unique among
trematodes because they have separate sexes. Several studies have shown that the sex ratio is often biased towards males.
Sexual dimorphism can be very important in several genera (Schistosoma, Heterobilharzia, Schistosomatium), as larger
males grip smaller females in a gynecophoric canal. But not all schistomatid species have developed a gynecophoric canal.
It is also striking that the number of testes varies widely, from a small number of testes reported (2–7) to a very high
number (>500). We tested the hypothesis of trade-off investment by males: muscle (as estimated by the length of the
gynecophoric canal) in order to sequester one or a few females, or testes in order to inseminate numerous females. We used
recent comparative methods, which need phylogenetic information of the analysed species. We employed a morphological
cladistic analysis of the Schistosomatidae and a construction of a phylogenetic supertree of Schistosoma based on available
molecular information. Our phylogenetic analysis supports previous hypotheses on the origin and diversification of the
schistosomes. The family seems to have originated as parasites of crocodiles (or possibly other related poikilotherms) and
to have secondarily evolved within the Aves and then mammals. Our phylogenetic analyses show that (1) the possession
of a gynecophoric canal is a plesiomorphic character, and several reductions of this character have occurred during the
diversification of the Schistosomatidae; (2) a small number of testes is a plesiomorphic stage, and an increase of testes
number has occurred several times. Finally, our comparative analysis suggests that there is a trade-off between investment
in muscle or in number of testes (other variables being controlled for). Male competition for access to females seems to
follow two ways: investment in testes in order to fertilize a high number of females or investment in muscle in order to
hold and sequester one (Schistosoma) or a few females (Heterobilharzia). We show the existence of the trade-off between
muscles and testes in connection with a male biased sex ratio. The development of dioecy cannot explain the trade-off
between muscles and testes, which instead appears to be a result of sexual selection possibly driven by the male biased
sex ratio.
Time, memory and the heritability of major depression
Authors: KENDLER KENNETH S. , AGGEN STEVE H.
Published: July 2002

Objective. Although family, twin and adoption studies have suggested that lifetime major depression (MD) is a heritable condition, nearly all these studies have relied for the diagnosis on long-term human memory, which is fallible and potentially biased. Could the estimates of heritability of MD be biased by the well-demonstrated genetic influences on memory?

Methods. Both members of 858 female–female twin pairs from a population-based registry were personally interviewed at least three times over 9 years. The interview assessed a history of depressive onsets and recoveries in the last year to the nearest month. We examine heritability of MD using four recall intervals: last year, last 6 months, last 3 months and current month.

Results. Examining the occurrence of one or more depressive episodes across all three interviews, heritabilities of MD (95% CI) for the four time periods were: 0·41 (0·27–0·54), 0·41 (0·26–0·55), 0·35 (0·16–0·52) and 0·34 (0·11–0·55). These heritability estimates did not differ significantly from one another. A similar pattern was found if heritability was assessed for the number of interviews in which criteria for MD were met.

Conclusion. Modelling results suggest that the heritability of MD was not influenced by the duration of the required recall. Genetic influences on human recall do not appear to contribute substantially to estimated heritability of MD.
Abnormal executive function in attention deficit hyperactivity disorder: the effect of stimulant medication and age on spatial working memory
Authors: BARNETT R. , MARUFF P. , VANCE A. , LUK E. S. L. , COSTIN J. , WOOD C. , PANTELIS C.
Published: July 2002

Objective. This study sought to examine the factors associated with spatial working memory and the use of strategies to impairments in spatial working memory in children with attention deficit hyperactivity disorder (ADHD). The developmental trajectories for spatial working memory in medicated and medication naïve children with ADHD were investigated. In addition, the effect of psychostimulant medication on deficits in spatial working memory was examined.

Method. A cross-sectional study compared performance between 21 psychostimulant medicated children with ADHD, 27 medication naïve children with ADHD and 26 matched control subjects on computerized tests of spatial memory and spatial working memory.

Results. Compared with the controls, performance in medication naïve children with ADHD was significantly worse on the spatial working memory task. There was no difference in performance between the medicated children with ADHD and the control subjects on this same task, despite the ongoing symptoms of ADHD in the former group. The pattern of normal and abnormal performance in the ADHD groups was age-independent.

Conclusions. Deficits in executive functions related to spatial working memory do occur in children with ADHD, although the magnitude of these deficits is not related to the child's age or the level of ADHD symptoms. These deficits were not present in the current sample of children who were receiving psychostimulant medication.
Quality of parenting and vulnerability to depression:

results from a family study
Authors: DUGGAN C. , SHAM P. , MINNE C. , LEE A. , MURRAY R.
Published: July 2002

Background. We examined a group of subjects at familial risk

of depression and explored the

relationship between the perceptions of parents and a history of

depression. We also investigated:

(a) whether any difference in perceived parenting found

between those with and without a past

history of depression was an artefact of the depression; and (b)

whether the relationship between

parenting and depression was explained by neuroticism.

Method. We took a sample of first-degree relatives selected

from a family study in depression and

subdivided them by their history of mental illness on the SADS-L, into

those: (a) without a history

of mental illness (N=43); and (b) those who had

fully recovered from an episode of RDC major

depression (N=34). We compared the perceptions of parenting,

as measured by the Parental

Bonding Instrument (PBI), in these two groups having adjusted for the

effect of neuroticism and

subsyndromal depressive symptoms. We also had informants report on

parenting of their siblings,

the latter being subdivided into those with and without a past history

of depression.

Results. Relatives with a past history of depression showed

lower care scores for both mother and

father combined compared with the never ill relatives. The presence of

a history of depression was

associated with a non-significant reduction in the self-report care

scores compared to the siblings

report. Vulnerable personality (as measured by high neuroticism) and

low perceived care were both

found to exert independent effects in discriminating between the

scores of relatives with and without

a history of depression and there was no interaction between them.

Conclusion. This study confirmed that low perceived

parental care was associated with a past history

of depression, that it was not entirely an artefact of having been

depressed, and suggested that this

association was partially independent of neuroticism.
Co-morbidity and familial aggregation of alcoholism and anxiety disorders
Authors: MERIKANGAS K. R. , STEVENS D. E. , FENTON B. , STOLAR M. , O'MALLEY S. , WOODS S. W. , RISCH N.
Published: July 2002

Background. This study examined the patterns of
familial aggregation and co-morbidity of
alcoholism and anxiety disorders in the relatives of 165 probands
selected for alcoholism and/or
anxiety disorders compared to those of 61 unaffected controls.

Methods. Probands were either selected from treatment
settings or at random from the community.
DSM-III-R diagnoses were obtained for all probands and their 1053
first-degree relatives, based on
direct interview or family history information.

Results. The findings indicate that: (1) alcoholism
was associated with anxiety disorders in the
relatives, particularly among females; (2) both alcoholism and
anxiety disorders were highly
familial; (3) the familial aggregation of alcoholism was
attributable to alcohol dependence rather
than to alcohol abuse, particularly among male relatives; and (4)
the pattern of co-aggregation of
alcohol dependence and anxiety disorders in families differed
according to the subtype of anxiety
disorder; there was evidence of a partly shared diathesis underlying
panic and alcoholism, whereas
social phobia and alcoholism tended to aggregate independently.

Conclusions. The finding that the onset of social phobia
tended to precede that of alcoholism, when
taken together with the independence of familial aggregation of
social phobia and alcoholism
support a self-medication hypothesis as the explanation for the
co-occurrence of social phobia and
alcoholism. In contrast, the lack of a systematic pattern in the
order of onset of panic and
alcoholism among subjects with both disorders as well as evidence
for shared underlying familial
risk factors suggests that co-morbidity between panic disorder and
alcoholism is not a consequence
of self-medication of panic symptoms. The results of this study
emphasize the importance of
examining co-morbid disorders and subtypes thereof in identifying
sources of heterogeneity in the pathogenesis of alcoholism.
Current and residual functional disability associated
with psychopathology: findings from the Netherlands
Mental Health Survey and Incidence Study (NEMESIS)
Authors: BIJL R. V. , RAVELLI A.
Published: July 2002

Background. Few population studies have investigated the functional disabilities that accompany
specific psychiatric diagnoses. This study assesses the nature and strength of current and residual
impairments in various functional domains of life.

Methods. Data were derived from the Netherlands Mental Health Survey and Incidence Study
(NEMESIS), a prospective study in the Dutch general population aged 18 to 64 (N = 7147).
Psychiatric diagnoses were based on the Composite International Diagnostic Interview; functional
disability was assessed on the basis of the Short-Form-36 and the number of disability days.

Results. Psychopathology was associated with increased disability in social, emotional and physical
domains of life. Disability levels varied by psychiatric diagnosis, with mood disorders showing the
poorest levels of functioning, especially for vitality and social functioning; alcohol-related disorders
were associated with few disabilities. Co-morbidity strongly aggravated the disability. The effect of
contextual factors on disability was limited, although somatic ill health, unemployment and adverse
youth history increased the likelihood of functional disability. The findings indicate that
psychopathology can also have residual debilitating effects.

Conclusions. Mental health care providers should be aware that the extent and the type of disability
may vary with the different types of disorders and among different groups within the population.
Since recovery from functional limitations may not be complete or may take more time than the
remission of the psychiatric symptomatology, non-psychiatric follow-up care is needed. The high
number of lost work days is relevant from an economic perspective. There is a need for illness-specific disability assessment instruments.
Recall of depressive episode 25 years previously
Authors: ANDREWS G. , ANSTEY K. , BRODATY H. , ISSAKIDIS C. , LUSCOMBE G.
Published: July 2002

Background. Lifetime rates of depression reported in epidemiological surveys are generally only
twice the 12 month rates. Either people forget the symptoms of depression or many people who have
a depressive episode remain depressed for many years. Both may be true. There is a need to examine
the long-term clinical validity of interviews that are used to make lifetime diagnoses.

Methods. Forty-five patients who were part of a long-term follow-up study of depression were
interviewed 25 years after the index episode. The diagnoses from the original, fully structured
interviews were compared with the responses people made for that period when interviewed using
the CIDI 25 years later.

Results. Twenty-seven patients met CIDI DSM-III-R criteria for depression at index episode. At the
25 year follow-up, 19 of the 27 reported the essential symptoms of ‘depression or loss of interest’
being present at the index time, and in 14 of the 27 the depressive symptoms recalled met criteria
for DSM-III-R major depressive episode at that time.

Conclusions. Seventy per cent of people who were hospitalized for a major depressive episode can
recall being depressed but only half can recall sufficient detail to satisfy the diagnostic criteria when
interviewed 25 years later. As depressive episodes, especially those severe enough to warrant
admission, are recalled better than many other diagnoses, one must be cautious about the lifetime
rates for mental disorders reported in retrospective epidemiological surveys.
Policy and Service Responses to Rough Sleeping Among Older People
Authors: CRANE MAUREEN , WARNES ANTHONY M.
Published: July 2002

Rough sleeping in Britain has a long history, and interventions have alternated
between legal sanctions and humanitarian concern. This paper critically
examines recent changes in homeless policies and services, with particular
reference to the needs of older people who sleep rough. The characteristics
and problems of the group are first described. Single homeless people
were formerly accommodated in direct-access hostels but, from the 1970s,
individualised rehabilitation and resettlement have spread. Most recently,
services dedicated to older people have begun (although remain few and are
unevenly provided). Their achievements are reviewed and drawn upon in
formulating normative proposals of the appropriate service mix. The 1990s
‘Rough Sleepers Initiative’ and related programmes promoted a ‘social care
market’ of not-for-profit organisations that compete for increased (but short-term)
funds to provide services, and the new Labour government will build
upon these changes and increase funds. Low tolerance towards the ‘social
exclusion’ of homelessness is promised but unerringly constructed as exclusion
from work; while rough sleeping is dubbed as anti-social, coercive
approaches to achieve a two-thirds reduction are foreseen. The proposed
target might stall the development of diverse and effective services, or reduce
providers' capacity to combat the perversities of resource allocation. The
overall prospects for the improvement and expansion of services to provide
significant help to single older homeless people are uncertain.
Garifuna children's language shame: Ethnic stereotypes,
national affiliation, and transnational immigration as
factors in language choice in southern Belize
Authors: BONNER DONNA M.
Published: July 2002

This article explores the effects of ethnic stereotypes,
demographic shifts, and nationalism on language choice
in the town of Dangriga, Belize. Dangriga was founded during
the nineteenth century by members of an ethnic minority
of West African and Native American heritage, known as
the Garinagu or Garifuna. Today, it is a multilingual and
multiethnic town populated primarily by Garinagu, Belizean
Creoles, and both native-born and foreign-born Spanish
speakers. In this context, language choice is in part a
question of affiliation with a variety of ethnic and national
identities. This article examines the manner in which ethnic
and national stereotypes and images, as well as current
demographic shifts in the Belizean population, affect language
choice in multilingual contexts. Particular attention is
paid to the position of young Garinagu vis-à-vis
the Garifuna language and Belizean English Creole.
On the need for conscious control and conceptual understanding
Authors: Marcovitch Stuart , Zelazo Philip David
Published: July 2002

The dynamic systems approach simulates a wide range of effects and generates novel predictions, but it fails to explain age-related behavioral changes in psychological terms. We argue that the roles of conscious control and explicit knowledge must be addressed in any model of A-not-B performance, and a fortiori, in any model of goal-directed action.
Understanding A-not-B errors as a function of object representation and deficits in attention rather than motor memories
Authors: Ruffman Ted
Published: July 2002

In this commentary, I raise several points. First, I argue that non-search tasks show that the A-not-B task is about object representation, even if perseveration can occur without objects. Second, I provide an alternative interpretation for the finding that changing body posture reduces A-not-B errors. Third, I provide an alternative interpretation for the finding of convergence in reaching behavior in two-target tasks. Fourth, I suggest attention deficits can explain the A-not-B error on their own with no necessity for motor memories.
Deictic codes for the embodiment of cognition
Authors: Ballard Dana H. , Hayhoe Mary M. , Pook Polly K. , Rao Rajesh P. N.
Published: July 2002

To describe phenomena that occur at different time scales,
computational models of the brain must incorporate different levels
of abstraction. At time scales of approximately 1/3 of a second,
orienting movements of the body play a crucial role in cognition and
form a useful computational level – more abstract than that
used to capture natural phenomena but less abstract than what is
traditionally used to study high-level cognitive processes such as
reasoning. At this “embodiment level,” the constraints
of the physical system determine the nature of cognitive operations.
The key synergy is that at time scales of about 1/3 of a second, the
natural sequentiality of body movements can be matched to the natural
computational economies of sequential decision systems through a
system of implicit reference called deictic in which pointing
movements are used to bind objects in the world to cognitive programs.
This target article focuses on how deictic bindings make it possible
to perform natural tasks. Deictic computation provides a mechanism
for representing the essential features that link external sensory
data with internal cognitive programs and motor actions. One of the
central features of cognition, working memory, can be related to
moment-by-moment dispositions of body features such as eye
movements and hand movements.