bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of surfactant on the stability of
a fluid filament embedded in a viscous fluid
Authors: HANSEN S. , PETERS G. W. M. , MEIJER H. E. H.
Published: July 2002

The effect of surfactant on the breakup of a viscous filament,
initially at rest,
surrounded by another viscous fluid is studied using linear stability analysis.
The role
of the surfactant is characterized by the elasticity number – a high
elasticity number
implies that surfactant is important. As expected, the surfactant slows
the growth
rate of disturbances. The influence of surfactant on the dominant wavenumber
is
less trivial. In the Stokes regime, the dominant wavenumber for most viscosity
ratios
increases with the elasticity number; for filament to matrix viscosity
ratios ranging
from about 0.03 to 0.4, the dominant wavenumber decreases when the elasticity

number increases. Interestingly, a surfactant does not affect the stability
of a filament
when the surface tension (or Reynolds) number is very large.
On the geometry of turbulent mixing
Authors: VILLERMAUX EMMANUEL , INNOCENTI CLAUDIA
Published: July 2002

We investigate the temporal evolution of the geometrical distribution of a passive
scalar injected continuously into the far field of a turbulent water jet at a scale
d smaller than the local integral scale of the turbulence. The concentration field
is studied quantitatively by a laser-induced- fluorescence technique on a plane cut
containing the jet axis. Global features such as the scalar dispersion from the source,
as well as the fine structure of the scalar field, are analysed. In particular, we define
the volume occupied by the regions whose concentration is larger than a given
concentration threshold (support of the scalar field) and the surface in which this
volume is enclosed (boundary of the support). The volume and surface extents,
and their respective fractal dimensions are measured as a function of time t, and
the concentration threshold is normalized by the initial concentration
Cs/C0 for
different injection sizes d. All of these quantities
display a clear dependence on t, d
and Cs, and their evolutions rescale with the variable
ξ = (ut/d)(Cs/C0),
the fractal dimension being, in addition, scale dependent. The surface-to-volume ratio and the
fractal dimension of both the volume and the surface tend towards unity at large ξ,
reflecting the sheet-like structure of the scalar at small scales. These findings suggest
an original picture of the kinetics of turbulent mixing.
On the spatial evolution of a wall-imposed
periodic disturbance in pipe Poiseuille flow at
Re = 3000. Part 1. Subcritical disturbance
Authors: MA B. , VAN DOORNE C. W. H. , ZHANG Z. , NIEUWSTADT F. T. M.
Published: July 2002

We have performed a numerical study on the transition of a cylindrical pipe flow under
the influence of a localized disturbance in the form of periodic suction and blowing
(PSB) applied at the pipe wall. We focus here on the so-called receptivity problem
where the spatial evolution of this disturbance is studied as it travels downstream
through the pipe. The study is carried out by means of two techniques: an eigenmode
expansion solution (EES) and a full nonlinear direct numerical simulation (DNS).
The EES is based on an analytical expansion in terms of the eigenfunctions of the
linear operator which follows from the equations of motion expressed in a cylindrical
coordinate system. The DNS is formulated in terms of a spectral element method.

We restrict ourselves to a so-called subcritical disturbance, i.e. the flow does not
undergo transition. For very small amplitudes of the PSB disturbance the results
of the EES and DNS techniques agree excellently. For larger amplitudes nonlinear
interactions come into play which are neglected in the EES method. Nevertheless, the
results of both methods are consistent with the following transition scenario. The PSB
excites a flow perturbation that has the same angular wavenumber and frequency as
the imposed disturbance itself. This perturbation is called the fundamental mode. By
nonlinear self-interaction of this fundamental mode higher-order harmonics, both in
the angular wavenumber and frequency, are generated. It is found that the harmonic
with angular wavenumber 2, i.e. twice the wavenumber of the fundamental mode, and
with zero frequency grows strongly by a linear process known as transient growth.
As a result the (perturbed) pipe flow downstream of the disturbance region develops
extended regions of low velocity, known as low-speed streaks. At large disturbance
amplitudes these low-speed streaks show the development of high wavenumber oscillations
and it is expected that at even higher disturbance amplitudes these oscillations
become unstable and turbulent flow will set in.

Our result agrees (at least qualitatively) with the transition scenario in a plane
Poiseuille flow as discussed by Reddy et al. (1998) and Elofson & Alfredson (1998).
Dispersive effects in Rossby-wave hydraulics
Authors: JOHNSON E. R. , CLARKE S. R.
Published: July 2002

This paper considers the role of long finite-amplitude Rossby waves in determining
the evolution of flow along a rapidly rotating channel with an uneven floor. The
Rossby waves travel on a potential vorticity interface in a channel with a cross-channel step change in depth, where step position varies slowly along the channel. A
nonlinear wave equation is derived describing the evolution of the potential vorticity
interface. To leading order this is the hydraulic equation derived by Haynes, Johnson
& Hurst (1993). Dispersion appears at the next order. Various solution regimes are
identified. As well as slowly varying hydraulic solutions, two further types of steady
solutions appear: approach-controlled flows and twin supercritical leaps. Both these
solutions are characterized by leaps between supercritical branches of the hydraulic
function. It is shown how the position and size of these ‘supercritical leaps’ can
be determined within the context of hydraulic theory. To fully resolve the internal
structure of these leaps dispersive effects must be included and leaps are shown to
correspond to kink soliton solutions of the steady unforced problem. It is also shown
that increasing dispersion (decreasing topographic length scale) causes the loss of the
subcritical solution branch in some subcritical flows. The only candidate for a steady
solution in these regimes is then an approach-controlled flow. Integrations of initial
value problems show that in general flows evolve towards the dispersive form of the
solution predicted by hydraulic theory, at least near the topographic perturbation.
However, in those subcritical flows where sufficiently large dispersion causes the
subcritical branch to disappear, unsteady integrations evolve to approach-controlled
flows even when the dispersion is sufficiently small that the subcritical branch still
exists.
Predicate union and the syntax of Japanese passives
Authors: DUBINSKY STANLEY
Published: July 2002

This paper presents a relational account of the Japanese

constructions that are

commonly referred to as ‘passives’. They are shown

to all be multipredicate,

monoclausal constructions, with the differences between them primarily
attributable

to optionality in the lexical argument structure of the

‘passive’ predicate. The

proposed analysis explains the differences between passives and causatives,
despite

their sometimes identical case-marking. Further, evidence from the interaction
of

unaccusative verbs and passive is shown to lead to a formal revision of
the

1-Advancement Exclusiveness law. Finally, the differences between Japanese
and

Korean with respect to passives is reduced to a simple lexical

difference between the two languages.
Some handy notes on phonology
Authors: LODGE KEN
Published: July 2002

J. A. Goldsmith (ed.),The handbook of phonological

theory. Cambridge, MA & Oxford: Blackwell, 1995. Pp. xiv + 986.

To assess a book of nearly a thousand pages with thirty-two contributions
is

something of a tall order, if not an impossible task, if one wants to do
justice

to all of it. For this reason, I have chosen to approach it from my own

standpoint on phonology and see to what extent the issues I see as crucial
to

the current vigorous debate in this area have been addressed and to examine

how they have been dealt with. First, however, I will present a general

description and discussion of the book as a whole.
Accountable to Themselves:

Predominance in Southern Africa
Authors: GOOD KENNETH
Published: July 2002

While public attention has focused on the stature of

Nelson Mandela, there has been at a deeper level in South Africa since

1990 a steep decline in state capacity, and a marked deterioration in

democratic practice. The participatory democracy which had so characterised

the decade of the 1980s was brought to a sharp end after the return of
the

nationalist leaders, and the workings of even a liberal, representative

democracy have also suffered under the rise since 1994 of a

predominant party system and élitism. The latter features are present

too in Namibia, with similar consequences. Democracy which is

understood merely as electoralism, as Botswana earlier had shown, has

few defences against predominance. The voters' brief electoral act
is

wide open to manipulation and containment. Power is shared by élites,

while popular participation is rendered moribund, and concern for

justice and equality ceases.
Parametric instabilities and wave coupling in
Alfvén simple waves
Authors: WEBB G. M. , ZAKHARIAN A. R. , BRIO M. , ZANK G. P.
Published: July 2002

A wave coupling formalism for magnetohydrodynamic (MHD) waves in
a non-uniform background flow is used to study parametric instabilities of the
large-amplitude, circularly polarized, simple plane Alfvén wave in one Cartesian
space dimension. The large-amplitude Alfvén wave (the pump wave) is regarded
as the background flow, and the seven small-amplitude MHD waves (the backward
and forward fast and slow magnetoacoustic waves, the backward and forward
Alfvén waves, and the entropy wave) interact with the pump wave via wave coupling
coefficients that depend on the gradients and time dependence of the background
flow. The dispersion equation for the waves D(k,ω) = 0 obtained from the
wave coupling equations reduces to that obtained by previous authors. The general
solution of the initial value problem for the waves is obtained by Fourier and
Laplace transforms. The dispersion function D(k,ω) is a fifth-order polynomial in
both the wavenumber k and the frequency ω. The regions of instability and the
neutral stability curves are determined. Instabilities that arise from solving the
dispersion equation D(k,ω) = 0, both in the form ω = ω(k), where k is real, and
in the form k = k(ω), where ω is real, are investigated. The instabilities depend
parametrically on the pump wave amplitude and on the plasma beta. The wave
interaction equations are also studied from the perspective of a single master wave
equation, with multiple wave modes, and with a source term due to the entropy
wave. The wave hierarchies for short- and long-wavelength waves of the master wave
equation are used to discuss wave stability. Expanding the dispersion equation for
the different long-wavelength eigenmodes about k = 0 yields either the linearized
Korteweg–deVries equation or the Schrödinger equation as the generic wave equation at long-wavelengths. The corresponding short-wavelength wave equations are
also obtained. Initial value problems for the wave interaction equations are investigated.
An inspection of the double-root solutions of the dispersion equation for k,
satisfying the equations D(k,ω) = 0 and ∂D(k,ω) = ∂k = 0 and pinch point analysis
shows that the solutions of the wave interaction equations for hump or pulse-like
initial data develop an absolute instability. Fourier solutions and asymptotic analysis
are used to study the absolute instability.
Ion phase-space vortices in 2.5-dimensional simulations
Authors: BØRVE STEINAR , PÉCSELI HANS L. , TRULSEN JAN
Published: July 2002

The formation and propagation of ion phase-space vortices are observed
in a numerical particle-in-cell simulation in two spatial dimensions and with three
velocity components. The code allows for an externally applied magnetic field. The
electrons are assumed to be isothermally Boltzmann-distributed at all times, implying
that Poisson's equation becomes nonlinear for the present problem. Ion phase-space
vortices are formed by the nonlinear saturation of the ion-ion two-stream
instability, excited by injecting an ion beam at the plasma boundary. We consider
the effect of a finite beam diameter and a magnetic field, in particular. A vortex instability
is observed, appearing as a transverse modulation, which slowly increases
with time and ultimately breaks up the vortex. When many vortices are present at
the same time, we find that it is their interaction that eventually leads to a gradual
filling-up of the phase-space structures. The ion phase-space vortices have a finite
lifetime, which is noticeably shorter than that found in one-dimensional simulations.
An externally imposed magnetic field can increase this lifetime considerably.
For high injected beam velocities in magnetized plasmas, we observe the excitation
of electrostatic ion-cyclotron instabilities, but see no associated formation of
ion phase-space vortices. The results are relevant, for instance, for the interpretation
of observations by instrumented spacecraft in the Earth's ionosphere and
magnetosphere.
Comment on ‘TM mode radiation guiding in an REB-induced plasma
duct’
Authors: SHOUCRI MAGDI
Published: July 2002

The propagation and dispersion relation of a TM mode in a plasma
duct in a slab
geometry has recently been studied by Parashar and Lalita [J.
Plasma Phys.55, 387 (1996)]. It is the purpose of the present note to

show that their dispersion relation is incorrect.
Generalized Trubnikov functions for unmagnetized plasmas
Authors: MELROSE D. B.
Published: July 2002

A class of relativistic dispersion functions for unmagnetized thermal plasmas
is defined by generalizing functions first defined by Trubnikov in 1958. Recursion relations
are derived that allow one to generate explicit expressions for the
class of functions in terms of the relativistic plasma dispersion function
T(z, ρ)
introduced by Godfrey et al. in 1975. These functions are relevant to the description
of the response of a weakly mangetized, highly relativistic, thermal plasma.
Ideal magnetohydrodynamic equilibria with
helical symmetry and incompressible flows
Authors: THROUMOULOPOULOS G. N. , TASSO H.
Published: July 2002

A recent study on axisymmetric ideal magnetohydrodynamic equilibria
with incompressible flows [H. Tasso and G. N. Throumoulopoulos, Phys. Plasmas5, 2378 (1998)] is extended to the generic case of helically symmetric equilibria
with incompressible flows. It is shown that the equilibrium states of the system
under consideration are governed by an elliptic partial differential equation for
the helical magnetic flux function containing five surface quantities along with
a relation for the pressure. The above-mentioned equation can be transformed to
one possessing a differential part identical in form to the corresponding static equilibrium
equation, which is amenable to several classes of analytical solutions. In
particular, equilibria with electric fields perpendicular to the magnetic surfaces and
non-constant-Mach-number flows are constructed. Unlike the case in axisymmetric
equilibria with isothermal magnetic surfaces, helically symmetric
T = T(ψ) equilibria
are overdetermined, i.e. in this case the equilibrium equations reduce to a set
of eight ordinary differential equations with seven surface quantities. In addition,
the non-existence is proved of incompressible helically symmetric equilibria with
(a) purely helical flows and (b) non-parallel flows with isothermal magnetic surfaces
and with the magnetic field modulus a surface quantity (omnigenous equilibria).
Does articulatory reduction miss more patterns than it accounts for?
Authors: Simpson Adrian P.
Published: July 2002

Articulatory explanations are often proposed to account for many of the phonetic patterns found in speech beyond the citation form. Unscripted material from Suffolk English and North German is used to argue that articulatory explanation can too tightly constrain our expectations of the types of phonetic patterns which spontaneous speech contains. It is also shown how articulatory explanation can offer an adequate account of a dataset, stopping short of revealing a larger, more complex set of phonetic patterns.
Numbers of naked amoebae inhabiting the intertidal zone of two geographically separate sandy beaches
Authors: Rogerson Andrew , Hannah Fiona , Hauer Gwen , Cowie Phillip
Published: July 2002

Numbers of naked amoebae (Gymnamoebae) inhabiting the lower intertidal zone of two sandy beaches were estimated using a novel enrichment cultivation method. Samples were collected between June and September, 1999. Beach sand at Kames Bay, Isle of Cumbrae, Scotland contained on average 2604 amoebae cm−3 while at Dania Beach, Florida, USA, sand harboured 4236 amoebae cm−3. This is the first study to focus on the abundance of naked amoebae inhabiting a sandy beach. These numbers are higher than densities generally reported for shallow subtidal sands and show that amoebae must be considered in future studies on the dynamics of sandy beach communities.
Longevity of oversized individuals: growth, parasitism, and history in an estuarine snail population
Authors: Curtis Lawrence A. , Kinley Jeffrey L. , Tanner Nathan L.
Published: July 2002

Ilyanassa obsoleta is mainly an eastern North American estuarine gastropod. Previous work on growth rate revealed a longevity of 30–40 y for this snail. Trematode infections retard growth, appear to be long-lived ([ges ]10 y) and can be frequent in this host. In 1995 a population made up of unusually large, trematode-parasitized individuals was located in Rehoboth Bay, Delaware. It was interesting to discover whether the oversized snails were the result of locally faster growth or greater age. Therefore in 1996 individually marked snails, uninfected and infected, were deployed to assess growth rates. Uninfected snails were tracked mostly in summer and autumn 1996; infected snails could be tracked longer, some through autumn 1999. Estimated growth rates of uninfected (1.5 mm y−1) and infected (0.2 mm y−1) snails in this habitat were similar to previous results and the large size of individuals in this population must be explained by greater age. Habitat history and growth rate evidence indicate the population includes snails as old as about 70 y. If correct, this becomes the greatest documented snail longevity. Trematodes gain long-term reproduction by their association with this host. By virtue of the enduring effects of long-lived individuals, and the wider potential effects of their long-lived infections (on the snails themselves and on other hosts in their life cycles), I. obsoleta stands to contribute more to the stability of coastal ecosystems than heretofore recognized.
Distribution and population structure of the rockfish Helicolenus dactylopterus (Pisces: Scorpaenidae) in the western Mediterranean
Authors: Massutí Enric , Moranta Joan , de Sola L. Gil , Morales-Nin B. , Prats Llucia
Published: July 2002

The distribution and spatio–temporal variation of Helicolenus dactylopterus (Pisces: Scorpaenidae) population was studied from 816 bottom trawls developed along the Iberian coast. Multifactor analysis of variance was used to test the differences in abundance and biomass and cluster analysis was applied to detect differences in population structure. The results showed a bathymetric and latitudinal gradient in abundance and population structure along three geographic sectors in the surveyed area. In the southern area, the species was more frequent and showed a wider bathymetric distribution range than northwards. The depth range with the maximum frequency of occurrence was also wider in the southern area than northwards. Similar trends were observed in terms of abundance and biomass, with the highest and lowest indices in the southern and northern areas, respectively. The age composition of the catches showed that the population consisted mainly of young-of-the-year and juvenile fish. This fraction of the population is well represented, at a mesoscale, along the whole surveyed area, but adults are well represented only at a local scale, at the deepest strata surveyed in the southern area. In this case, recruits of age 0 and juveniles up to 4-y old were restricted to depths shallower than 500 m, while adult fish older than 6 y of age appeared below this depth. In the southern area, seasonal changes in the population structure were also observed, with modes of small fish (3–6 cm) from March to June, as a consequence of the species recruitment to the bottom. Some direct and indirect factors of biogeographic, environmental and anthropogenic origin affecting the observed gradient are discussed.
Occurrence of hydromedusae in the plankton off Northumberland (western central North Sea) and the role of planktonic predators
Authors: Nicholas K.R. , Frid C.L.J.
Published: July 2002

The pattern of occurrence of medusae off the north-east coast of England are described for the period 1990–1996. The predatory role of the medusae, Aglantha digitale, was examined by comparison of estimated predation rates with those of other planktonic predators. Aglanthe digitale was found to have the potential to considerably reduce copepod abundances, particularly in winter. Other important predators were the amphipod Themisto compressa and the chaetognath Sagitta elegans. There was a great deal of seasonal and interannual variability in predatory impact, with predators such as Pleurobrachia pileus and Meganyctiphanes norvegica occasionally exerting a high predatory impact. Previous studies have identified an important community structuring role for predation in winter in this area, this study shows that planktonic predators can influence copepod abundances throughout the year.
Kinship Politics in Post-War Philippines: The Lopez Family, 1945–1989
Authors: Roces Mina
Published: July 2002

On being awarded the Legion of Honor by President Corazon Aquino, Joaquin ‘Chino.’ Roces, publisher of The Manila Times, pleaded with the president:

Please allow me to remind you, first. That our people brought a new government to power because our people felt an urgent need for change. That change was nothing more and nothing less than that of moving quickly into a new moral order. The people believed, and many of them still do, that when we said we would be the exact opposite of Marcos, we would be just that. Because of that promise which the people believed, our triumph over Marcos was anchored on a principle of morality . . . . To our people, I dare propose that new moral order is best appreciated in terms of our response to graft and corruption in public service. We cannot afford a government of thieves unless we can tolerate a nation of highwaymen.
Courts of Law and Styles of Self in Eighteenth-Century Madras: From Hybrid to Colonial Self
Authors: MINES MATTISON
Published: July 2002

My concern is public representations of individuals and how these were affected by British East India Company courts,
judicial proceedings, and the law in Madras city during the eighteenth and early nineteenth centuries. Company records
reveal that this was a period of dramatic transformation in self-representation, just as it also was in Company rule. My
purpose is to trace the transformation of the manner in which individuals represented themselves and others and what
this process reveals about the constitution of Madras society and Company rule before and after the establishment of
an independent judiciary at the end of the eighteenth century. Most particularly, in this paper I seek to demonstrate
how the transformation of East India Company courts of judicature from interested courts, strictly controlled by the
Company, to independent courts is associated with changes that greatly affected the manner in which
individuals—both British and Indian—thought of themselves and others in Madras city public life. This transformation was of a
piece with the establishment of independent judiciaries in England and North America at the time and indicates how
Madras too was influenced by these political developments.
Shipping and Trade in Java, c. 1775: A Quantitative Analysis
Authors: Knaap Gerrit
Published: July 2002

Since the 1930s shipping and trade in Southeast Asia during the early modern period have attracted much attention from historians. The pioneer in this field was the Dutch scholar, J. C. van Leur, whose original work was translated into English during the 1950s (Van Leur 1955). Van Leur's interest was heavily weighted toward what he labelled ‘old Asian trade,’ and as such he was one of the first who called for an Asia-centric perspective. He drew attention to the fact that the maritime sector of Southeast Asia had its own dynamics. In the 1960s, M. A. P. Meilink-Roelofsz carried on the work of analyzing the indigenous maritime sector as well as the effects of the Portuguese and Dutch onslaughts on it up to the 1630s (Meilink-Roelofsz 1962). Limiting our perspective to the Malayo-Indonesian Archipelago, in the last decade several regional case studies have further enhanced our knowledge of the subject, such as those on Sulu (Warren 1981), Batavia (Blussé 1986), Amboina (Knaap 1987), Central and East Java (Nagtegaal 1988), and the Straits of Malacca (Vos 1993). Furthermore, Anthony Reid has recently tried to create a synthesis for the entire region of Southeast Asia up to 1680 (Reid 1993).
Changes in the lipid content and fatty acid composition of

2nd-stage juveniles of Globodera rostochiensis after

rehydration, exposure to the hatching stimulus and hatch
Authors: HOLZ R. A. , WRIGHT D. J. , PERRY R. N.
Published: July 2002

The total lipid content of the dry weight of whole

cysts and 2nd-stage juveniles (J2) of Globodera

rostochiensis was 17·1%

in dry cysts, 20·9% in cysts soaked in distilled water (DW),

20·3% in cysts that had been in potato root diffusate (PRD)

for 7 days, 7·3% in cysts that had been in PRD for 28 days

and 29·2% for hatched J2. The fatty acid composition of the

total lipid did not differ between dry cysts, cysts in DW and

cysts in PRD for 7 days. However, major differences in the

fatty acid composition of all lipid classes were found between

rehydrated cysts in PRD and freshly hatched J2. After

hatching, the degree of saturation and the percentage of

monounsaturated fatty acids decreased and the percentage of

polyunsaturated fatty acids increased considerably, especially

in the free fatty acid fraction, where C20[ratio ]1 showed an

8-fold decrease and C20[ratio ]4 a 33-fold increase. There was a

difference in the fatty acid composition of cysts in PRD for 7

days and cysts in PRD for 28 days (after most of the J2 had

hatched); with increased time in PRD the percentage of

polyunsaturated fatty acids increased and the percentage of

monounsaturated fatty acids decreased in all lipid classes.

Differences in the fatty acid profiles between cysts in PRD for

28 days and hatched J2 were found mainly in the free fatty

acid and the non-acidic phospholipid fractions. The free fatty

acid fraction of the cysts was dominated by monounsaturated

fatty acids (52%), whereas the same fraction of hatched J2

contained large amounts of polyunsaturated fatty acids (60%).

These polyunsaturated fatty acids, especially C20[ratio ]4,

might play an important part in nematode–plant

interactions during infection.
Onchocerca ochengi: assessment of the Simulium
vectors in
North Cameroon
Authors: WAHL G. , EKALE D. , SCHMITZ A.
Published: July 2002

In the savanna areas of tropical Africa, cattle are frequently
infected with
the filaria Onchocerca ochengi. This parasite is
closely related to Onchocerca volvulus, the causative agent of

human onchocerciasis (river blindness), and is capable of
developing in the same vector, Simulium damnosum s.l. In North

Cameroon, where both O. ochengi and O. volvulus are
endemic, we carried out a field study (reported in this and 2 following

papers) to examine to which extent the transmission
of the 2 parasite species overlap and what influence this has on the
epidemiology of human onchocerciasis. In this paper
we report our experiments to determine which of the S. damnosum

species in North Cameroon act as vectors of O. ochengi,
how efficiently they do so and whether other Simulium species
play
a vector role. To this end, infected cattle were exposed
near 5 rivers in different geographical areas. Among 14 Simulium

species identified as aquatic and/or adult stages at these
rivers, only 6 (S. squamosum, S. damnosum s.s., S.
sirbanum,
S. bovis, S. wellmanni and S. hargreavesi) were
found to bite
cattle in important numbers in at least 1 of the sites. The 3 species of
the
S. damnosum complex were all capable of
ingesting microfilariae (mf) of O. ochengi and developing a proportion

of them to infective larvae (L3). Whereas S.
squamosum and S. damnosum s.s., the prevailing vectors in
the
Guinea and Sudan savanna respectively, showed a high
vector competence (17% of ingested mf developed to L3), S. sirbanum,

which was much rarer in both areas, appeared to
have a much lower susceptibility (2%). Other boophilic Simulium

species were only seen in certain sites and seasons, being
either incapable of ingesting important numbers of O. ochengi
mf
from body regions where these mf were abundant (S.
bovis, S. hargreavesi); not able to support the development

of ingested mf to L3 (S. wellmanni), or bit cattle preferentially

in the ears, where O. ochengi mf do not occur (S. hargreavesi).

We conclude that in North Cameroon members of the S. damnosum

complex are the only important vectors of O. ochengi, with
S. squamosum and S. damnosum s.s. being the main vectors.
Irradiated sporozoites prime mice to produce high
antibody titres upon viable Plasmodium berghei sporozoite
challenge, which act upon liver-stage development
Authors: CHATTERJEE S. , DRUILHE P. , WERY M.
Published: July 2002

C57BL6 mice were protected against Plasmodium berghei
sporozoite challenge by immunization with live 12 krad dose-irradiated sporozoites, but not by 20 krad dose-irradiated sporozoites.
Immunization with 12 krad irradiated sporozoites
generated low levels of antibody reactive to liver-stage parasites (titres
of 1/100). Inoculation of as few as 100 live P. berghei
sporozoites induced complete host protection accompanied by a very quick
and high boost of antibody titres up to 1/4000.
This sporozoite challenge-drive antibody boost was absent in mice immunized
by 20 krad sporozoites and in non-protected, and non-immunized mice. Antibody was mainly liver-stage (LS)
specific and due to an increase of IgG2a and
IgG2b. The in vitro effect of pre- and post-challenge
sera upon either sporozoite invasion or LS development was assessed
in Hep-G2 cultures. Both were found to have a strong effect upon LS development
even at 1/2500 dilution, and conversely
a low effect upon invasion. These results suggest that sporozoites irradiated
at doses that induce protection are able to
prime T-cells which, upon challenge by non-irradiated sporozoites, provide
help to B-lymphocytes to trigger the
production of high titres of anti-LS antibodies that can inhibit LS development
in vitro.
A clonal Plasmodium falciparum population in an isolated

outbreak of malaria in the Republic of Cabo Verde
Authors: AREZ A. P. , SNOUNOU G. , PINTO J. , SOUSA C. A. , MODIANO D. , RIBEIRO H. , FRANCO A. S. , ALVES J. , do ROSARIO V. E.
Published: July 2002

We present the first parasitological, molecular and longitudinal
analysis of an isolated outbreak of malaria. This outbreak
occurred on Santiago Island (Republic of Cabo Verde), a region where malaria
is hypoendemic and controlled, and thus
the population is considered non-immune. Blood samples were collected from
the inhabitants over 1 month and during
cross-sectional surveys in the following year. The presence and nature
of the parasites was determined by PCR. Plasmodium
falciparum was the only species detected. Genetic analysis revealed
that the circulating parasites were genetically
homogeneous, and probably clonal. Gametocytes were found throughout this
period. Our data suggest that this represented a
focal outbreak, resulting in the infection of at least 40% of the villagers
with a clonal parasite line. Thus, P. falciparum
infections can persist for at least 1 year in a substantial proportion
(10%) of the hosts. Implications for malaria control
and the interpretation of epidemiological data are discussed.
Theileria parva ribosomal internal transcribed spacer
sequences exhibit extensive polymorphism and mosaic
evolution: application to the characterization of parasites
from cattle and buffalo
Authors: COLLINS N. E. , ALLSOPP B. A.
Published: July 2002

We sequenced the rRNA genes and internal transcribed spacers (ITS) of several Theileria parva isolates in an attempt to
distinguish between the causative agents of East coast fever and Corridor disease. The small subunit (SSU) and large
subunit (LSU) rRNA genes from a cloned T. p. lawrencei parasite were sequenced; the former was identical to that of
T. p. parva Muguga, and there were minor heterogeneities in the latter. The 5·8S gene sequences of 11 T. parva isolates were
identical, but major differences were found in the ITS. Six characterization oligonucleotides were designed to hybridize
within the variable ITS1 region; 93·5% of T. p. parva isolates examined were detected by probe TPP1 and 81·8% of
T. p. lawrencei isolates were detected by TPL2 and/or TPL3a. There was no absolute distinction between T. p. parva and
T. p. lawrencei and the former hybridized with fewer of the probes than did the latter. It therefore seems that a relatively
homogenous subpopulation of T. parva has been selected in cattle from a more diverse gene pool in buffalo. The ITSs
of both T. p. parva and T. p. lawrencei contained different combinations of identifiable sequence segments, resulting in
a mosaic of segments in any one isolate, suggesting that the two populations undergo genetic recombination and that their
gene pools are not completely separate.
Development of irreversible lesions in the brain, heart and
kidney following acute and chronic murine malaria infection
Authors: VUONG P. N. , RICHARD F. , SNOUNOU G. , COQUELIN F. , RÉNIA L. , GONNET F. , CHABAUD A. G. , LANDAU I.
Published: July 2002

Irreversible pathological lesions were noted in the organs of mice infected with 1 of 3 rodent malaria species: Plasmodium
chabaudi chabaudi, P. vinckei petteri and P. yoelii nigeriensis at different times during the course of the primary parasitaemia
and long after microscopical clearance of the parasites. Moreover, similar lesions were also obtained when parasite levels
were kept below 1%by subcurative drug treatment. The frequency and severity of the lesions correlated with the duration
of the infection. Accumulation of tissue damage during chronic low-grade malaria infections has implications for the
design of control measures.
The role of lambs in louping-ill virus amplification
Authors: LAURENSON M. K. , NORMAN R. , REID H. W. , POW I. , NEWBORN D. , HUDSON P. J.
Published: July 2002

In some areas of Scotland, the prevalence of louping-ill virus has not decreased despite the vaccination of replacement
ewes for over 30 years. The role of unvaccinated lambs in viral persistence was examined through a combination of an
empirical study of infection rates of lambs and mathematical modelling. Serological sampling revealed that most lambs
were protected by colostral immunity at turnout in May/June but were fully susceptible by the end of September. Between
8 and 83% of lambs were infected over the first season, with seroconversion rates greater in late rather than early summer.
The proportion of lambs that could have amplified the louping-ill virus was low, however, because high initial titres of
colostral antibody on farms with a high force of infection gave protection for several months. A simple mathematical model
suggested that the relationship between the force of infection and the percentage of lambs that became viraemic was not
linear and that the maximum percentage of viraemic lambs occurred at moderately high infection rates. Examination of
the conditions required for louping-ill persistence suggested that the virus could theoretically persist in a sheep flock with
over 370 lambs, if the grazing season was longer than 130 days. In practice, however, lamb viraemia is not a general
explanation for louping-ill virus persistence as these conditions are not met in most management systems and because the
widespread use of acaracides in most tick-affected hill farming systems reduces the number of ticks feeding successfully.
Population dynamics of Plasmodium falciparum in an
unstable malaria area of eastern Sudan
Authors: BABIKER H. A. , ABDEL-MUHSIN A. A. , HAMAD A. , MACKINNON M. J. , HILL W. G. , WALLIKER D.
Published: July 2002

The Plasmodium falciparum population in Asar village, eastern Sudan, where malaria transmission is markedly seasonal,
was monitored monthly over a period of 15 months. A cohort of infected patients was treated and then followed monthly
throughout the dry season until the next transmission season. Parasitaemia detected by microscopy among the cohort
reduced dramatically following treatment, but remained sporadic during the dry season, and reappeared following the
onset of the next wet season. However between 40 and 50% of the cohort retained a persisting parasitaemia detectable
by PCR throughout the dry season. These parasites were genetically complex, consisting of multiple clones with a large
repertoire of alleles of the studied genes. While the number of clones per host dropped significantly following treatment
of acute cases during the transmission season, drug treated people nevertheless maintained an average of one clone
throughout the dry season. Allele frequencies of MSP-1, MSP-2 and GLURP showed slight, statistically insignificant,
fluctuations between the dry and wet seasons. A higher frequency of inbreeding was estimated among the parasites that
survived the dry season compared to the wet season.
The Moral. The Personal, and the Importance of What We Care About
Authors: Benbaji Yitzhak
Published: July 2002

This paper challenges what I call ‘Frankfurt's Care-Importance Principle’ (or ‘the CIP’), according to which, ‘If there is something that a person does care about, then it follows that it is important to him.’ Indeed, caring may generate genuine importance. I claim, however, that the agent's caring may have blinding effects too, it may blind him to what is really important to him. In this kind of case, caring does not generate genuine importance; rather, it reinforces the agent's false belief that what he cares about is really important to him. In the second part of the paper, I try to explain the philosophical urgency in correcting the CIP. I claim that Frankfurt's adherence to the CIP casts doubt upon the adequacy of his conceptual framework to deal with a special kind of conflict, namely, the conflict between the moral and the personal.
Two Distinctions that do make a Difference: The Action/Omission Distinction and the Principle of Double Effect
Authors: Chappell Timothy
Published: July 2002

The paper outlines and explores a possible strategy for defending both the action/omission distinction (AOD) and the principle of double effect (PDE). The strategy is to argue that there are degrees of actionhood, and that we are in general less responsible for what has a lower degree of actionhood, because of that lower degree. Moreover, what we omit generally has a lower degree of actionhood than what we actively do, and what we do under known-but-not-intended descriptions generally has a lower degree of actionhood than what we do under known-and-intended descriptions. Therefore, we are in general less responsible for what we omit than for what we do—which is just what AOD says. And we are in general less responsible for what we do under known-but-not-intended descriptions than for what we do under known-and-intended descriptions—which is just what PDE says.
Sensitivity to linguistic anomalies in spoken
sentences: a case study approach to understanding
thought disorder in schizophrenia
Authors: KUPERBERG G. R. , McGUIRE P. K. , DAVID A. S.
Published: July 2002

Background. As a group, positively thought-disordered (TD) schizophrenic patients are relatively
impaired in their ability to use linguistic context to process sentences online (Kuperberg et al. 1998).
This study investigates the heterogeneity in the use of linguistic context both between individual TD
patients and within the individual patients as severity of thought disorder changes over time.

Methods. Seventeen TD schizophrenics performed an online word-monitoring task on four
separate occasions. In each patient, baseline reaction time (RTs) to target words in normal sentences
were subtracted from RTs to target words in pragmatically-, semantically- and syntactically-violated sentences to obtain a measure of online sensitivity to each type of linguistic violation, and
these were compared with normative data of a healthy volunteer and a non-TD schizophrenic
control group. In addition, the co-variation of severity of thought disorder and sensitivity to
linguistic context within all individual TD patients over the four testing sessions, was examined.

Results. There was marked heterogeneity between individual TD patients in their sensitivity to
different types of linguistic violations: some were selectively insensitive to pragmatic violations,
while others were insensitive to semantic and syntactic (subcategorization) violations. There was
also an inverse relationship between severity of thought disorder and sensitivity to linguistic
violations within individual patients over the four sessions.

Conclusions. It is likely that a single cognitive deficit does not account for all types of schizophrenic
thought disorder, but rather that there are multiple deficits affecting specific levels of linguistic
processing. In these schizophrenic patients, impairment in the use of linguistic context was related
to the state, rather than the trait, of thought disorder.
Early risk factors and adult person–environment
relationships in affective disorder
Authors: VAN OS JIM , JONES PETER B.
Published: July 2002

Background. Lower cognitive ability, higher neuroticism and symptoms of anxiety and depression
in childhood predict non-psychotic disorder in adulthood. This study examined whether these early
risk factors act by modifying relationships with life events close to disease onset in adulthood.

Methods. Childhood measures of neuroticism (N) (including maternal N), cognitive ability (CA)
and symptoms of anxiety and depression were measured in a national British birth cohort of 5362
individuals born in the week 3–9 March, 1946. At ages 36 and 43 years, mental state examinations
were carried out by trained interviewers, and subjects were asked about the occurrence of stressful
life events in the previous year (SLE).

Results. The effect of aggregated SLEs on mental health was greater in women, in individuals with
higher childhood N and poorer childhood mental health. Higher maternal N was also associated
with greater sensitivity to SLEs, independent of subject's N, suggesting possible familial
transmission of vulnerability. In addition, higher childhood N predicted, independent of later
mental health, greater likelihood of reported exposure to SLEs. In general, individuals with higher
childhood CA also reported more SLEs.

Conclusions. The results suggest that early risk factors for affective disorder exert effects by
modifying person–environment relationships close to onset of adult symptoms. Sensitivity to life
events may be transmitted from parents to offspring; psychopathological continuity over the life-span may be explained in part by continuity of altered stress sensitivity.
Trifluoroethanol and colleagues: cosolvents
come of age. Recent studies with peptides and proteins
Authors: BUCK MATTHIAS
Published: July 2002

Alcohol based cosolvents, such as trifluoroethanol (TFE) have been used for
many decades to denature proteins and to stabilize structures in peptides.
Nuclear magnetic resonance spectroscopy and site directed mutagenesis have
recently made it possible to characterize the effects of TFE and of other
alcohols on polypeptide structure and dynamics at high resolution. This review
examines such studies, particularly of hen lysozyme and β-lactoglobulin. It
presents an overview of what has been learnt about conformational preferences
of the polypeptide chain, the interactions that stabilize structures and the
nature of the denatured states. The effect of TFE on transition states and on
the pathways of protein folding and unfolding are also reviewed. Despite
considerable progress there is as yet no single mechanism that accounts for all
of the effects TFE and related cosolvents have on polypeptide conformation.
However, a number of critical questions are beginning to be answered. Studies
with alcohols such as TFE, and ‘cosolvent engineering’ in general, have
become valuable tools for probing biomolecular structure, function and
dynamics.

1. COSOLVENTS: OLD HAT? 298

2. HOW DOES TFE WORK? 299

2.1 Effect on hydrogen bonding 300

2.2 Effect on non-polar sidechains 301

2.3 Effect on solvent structure 302

3. EFFECTS OF TFE ON (UN-)FOLDING TRANSITIONS 303

3.1 Pretransition 303

3.2 Transition 304

3.3 Posttransition 305

3.4 Far UV CD spectroscopic detection of structure 306

3.5 Effect with temperature 306

3.6 Effect with additional denaturants 306

4. THERMODYNAMIC PARAMETERS FROM STRUCTURAL TRANSITIONS OF PEPTIDES AND PROTEINS IN TFE 307

5. ADVANCES IN NMR SPECTROSCOPY 310

5.1 Chemical shifts 310

5.2 3[Jscr ]HNHαcoupling constants 311

5.3 Amide hydrogen exchange 312

5.4 Nuclear Overhauser Effects (NOEs) 312

6. α-HELIX – EVERYWHERE? 313

6.1 Intrinsic helix propensity equals helix content? 313

6.2 A helix propensity scale for the amino acids in TFE 314

6.3 Capping motifs and stop signals 315

6.4 Limits and population of helices as seen by CD and NMR 316

7. TURNS 317

8. β-HAIRPINS AND SHEETS 317

9. ‘CLUSTERS’ OF SIDECHAINS 320

10. THE TFE DENATURED STATE OF β-LACTOGLOBULIN 321

11. THE TFE DENATURED STATE OF HEN LYSOZYME 324

12. TERTIARY STRUCTURE, DISULPHIDES, DYNAMICS AND COMPACTNESS 327

13. PROSPECTS FOR STRUCTURE CALCULATION 328

14. EFFECT OF TFE ON QUATERNARY STRUCTURE 329

15. EFFECT ON TFE ON UN- AND REFOLDING KINETICS 330

16. OTHER USES 336

16.1 Mimicking membranes and protein receptors 336

16.2 Solubilizing peptides and proteins 336

16.3 Cosolvents as helpers for protein folding? 338

16.4 Modifying protein dynamics and catalysis 338

16.5 Effects on nucleic acids 339

16.6 Effects on lipid bilayers and micelles 339

16.7 Future applications 339

17. CONCLUSIONS: TFE – WHAT IS IT GOOD FOR? 340

18. ACKNOWLEDGMENTS 340

19. REFERENCES 340
Malebranche's natural theodicy and the incompleteness of God's volitions
Authors: PESSIN ANDREW
Published: July 2002

The causal power of Malebranche's God is a function of the content of
His will. Yet despite its significance for Malebranche, little exegetical attention has
been paid to his notion of volitional content. In this paper I develop the notion of an
‘incomplete’ volition, note that Malebranche accepted and used something like it,
and then examine Malebranche's natural theodicy in its light. This yields a new
interpretation in which, unlike previous interpretations, Malebranche actually
succeeds in reconciling his seemingly incompatible beliefs that: (1) God alone is
causally responsible for all natural states of affairs; (2) God's power is His will; (3)
God wills to produce only goods; and yet (4) genuine evils exist.