To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Depuis une dizaine d’années, l’entraînement cognitif est un type d’intervention non pharmacologique qui s’est développé afin de favoriser la réhabilitation après un traumatisme crânien ou un accident vasculaire cérébral. Le but de cette intervention est l’amélioration du fonctionnement cognitif par la répétition d’exercices généralement informatisés . Cette intervention peut être envisagée dans le traitement du Trouble de Déficit de l’Attention/Hyperactivité (TDA/H) car ce trouble est associé à un déficit du fonctionnement cognitif . À ce jour, la majorité des études TDA/H portent sur l’entraînement de la mémoire de travail par le programme Cogmed. Mais, les résultats des études sont controversés quant à l’impact du programme sur : le fonctionnement cognitif, les symptômes liés au TDA/H et les performances scolaires . Face à ces constats, une première étude est réalisée au Québec auprès d’enfants présentant un Trouble de Déficit de l’Attention/Hyperactivité (TDA/H). Une seconde étude est réalisée en France auprès d’adultes présentant ce même trouble. L’objectif principal commun de ces deux études est d’évaluer l’efficacité d’un entraînement de la mémoire de travail assisté par ordinateur (Cogmed) sur les symptômes liés au TDA/H et le fonctionnement cognitif auprès (1) d’enfants, et (2) d’adultes présentant un TDA/H. Les objectifs secondaires de l’étude réalisée auprès d‘enfants sont d’évaluer l’efficacité du programme sur le rendement scolaire. Pour l’étude réalisée auprès d’adultes, les objectifs secondaires sont d’évaluer les effets du programme sur : (1) la symptomatologie anxieuse et (2) dépressive. Les deux études sont réalisées en double insu et comprennent une assignation aléatoire des participants. Pour chacune des deux études un groupe témoin actif durant lequel les participants réalisent également des exercices d’entraînement assistés par ordinateur est constitué. Toutefois, dans ce programme les exercices d’entraînement demeurent à un niveau de difficulté limité, ce qui a pour impact d’en réduire les effets. Les résultats de ces deux études sont présentés.
La mémoire de travail est une fonction cognitive souvent affectée, dans le contexte d’un TDAH . L’entraînement de la mémoire de travail par le programme informatisé Cogmed est une intervention qui est proposée auprès des patients présentant un TDAH . Le but de cette intervention est l’amélioration de la mémoire de travail par la répétition d’exercices généralement informatisés . Les résultats des études évaluant les effets du programme Cogmed auprès de participants présentant TDAH, indiquent que cette intervention améliore la mémoire de travail . Cependant, selon ces auteurs le maintien des effets de cette intervention sur plusieurs mois ne sont pas attestés. Afin de pallier à cette limite, deux études sont présentées. L’une est réalisée en France auprès d’adultes présentant un TDAH et la seconde au Québec auprès d’enfants présentant ce même trouble. L’objectif de ces études est d’évaluer le maintien des effets à six mois d’un entraînement de la mémoire de travail assisté par ordinateur (Cogmed) sur les symptômes liés au TDAH, la mémoire de travail, le raisonnement non verbal, l’inhibition et les capacités attentionnelles. Le maintien des effets pour la compréhension de la lecture et le raisonnement mathématique est également évalué auprès des enfants. Pour les deux études, les participants sont assignés aléatoirement dans une des deux conditions suivantes :
– le groupe d’entraînement Cogmed ;
– un groupe témoin actif (version placebo du programme), durant cette version les mêmes activités que celles proposées par le programme Cogmed sont effectuées.
Toutefois, le niveau de difficulté demeure faible et constant à travers le temps, ce qui devrait avoir pour effet d’en restreindre l’efficacité. Les évaluations sont réalisées en double insu. Les résultats des effets du programme six mois après l’intervention seront présentés.
When a promising natural enemy of a key pest exists locally, it is a common practice in biological control (BC) to rear and release it for supplementary control in the targeted agroecosystem even though significant knowledge gaps concerning pre/post release may still exist. Incorporating genetic information into BC research fills some of these gaps. Habrobracon hebetor, a parasitoid of many economically important moths that infest stored and field crops worldwide is commonly used, particularly against the millet head miner (MHM), a key pest of millet in Sahelian countries. To advance our knowledge on how H. hebetor that occurs naturally in open-field cropping systems and grain stores as well as being mass-produced and released for MHM control, performs in millet agroecosystems in Niger we evaluated its population genetics using two mitochondrial and 21 microsatellite markers. The field samples were genetically more diverse and displayed heterozygote excess. Very few field samples had faced significant recent demographic bottlenecks. The mating system (i.e. nonrandom mating with complementary sex determination) of this species may be the major driver of these findings rather than bottlenecks caused by the small number of individuals released and the scarcity of hosts during the longlasting dry season in Niger. H. hebetor population structure was represented by several small patches and genetically distinct individuals. Gene flow occurred at local and regional scales through human-mediated and natural short-distance dispersal. These findings highlight the importance of the mating system in the genetic diversity and structure of H. hebetor populations, and contribute to our understanding of its reported efficacy against MHM in pearl millet fields.
Projections of Paleoindian range mobility in the late Pleistocene are typically inferred from straight-line distances between toolstone sources and sites where artifacts of these raw materials have been found. Often, however, these sourcing assessments are not based on geologic analysis, raising the issue of correct source ascription. If sites of similar age can be linked to a toolstone source through geologic study, and direct procurement of toolstone can be inferred, geographic information systems (GIS) modeling of travel routes between the source and those sites can reveal route segments of annual rounds and aspects of landscape use. In the Hudson Valley of eastern New York, Paleoindian peoples exploited Normanskill chert outcrops for toolstone during the late Pleistocene. Here, we combine X-ray fluorescence sourcing results that link Normanskill chert artifacts at Paleoindian sites to the West Athens Hill source outcrop in the Hudson Valley with GIS least cost path analysis to model seasonal pathways of late Pleistocene peoples in northeastern North America.
Self-similar solutions to the compressible Euler equations with nonlinear conduction are considered as particular instances of unsteady radiative deflagration – or ‘ablation’ – waves with the goal of characterizing the actual hydrodynamic properties that such flows may present. The chosen family of solutions, corresponding to the ablation of an initially quiescent perfectly cold and homogeneous semi-infinite slab of inviscid compressible gas under the action of increasing external pressures and radiation fluxes, is well suited to the description of the early ablation of a target by gas-filled cavity X-rays in experiments of high energy density physics. These solutions are presently computed by means of a highly accurate numerical method for the radiative conduction model of a fully ionized plasma under the approximation of a non-isothermal leading shock wave. The resulting set of solutions is unique for its high fidelity description of the flows down to their finest scales and its extensive exploration of external pressure and radiative flux ranges. Two different dimensionless formulations of the equations of motion are put forth, yielding two classifications of these solutions which are used for carrying out a quantitative hydrodynamic analysis of the corresponding flows. Based on the main flow characteristic lengths and on standard characteristic numbers (Mach, Péclet, stratification and Froude numbers), this analysis points out the compressibility and inhomogeneity of the present ablative waves. This compressibility is further analysed to be too high, whether in terms of flow speed or stratification, for the low Mach number approximation, often used in hydrodynamic stability analyses of ablation fronts in inertial confinement fusion (ICF), to be relevant for describing these waves, and more specifically those with fast expansions which are of interest in ICF. Temperature stratification is also shown to induce, through the nonlinear conductivity, supersonic upstream propagation of heat-flux waves, besides a modified propagation of quasi-isothermal acoustic waves, in the flow conduction regions. This description significantly departs from the commonly admitted depiction of a quasi-isothermal conduction region where wave propagation is exclusively ascribed to isothermal acoustics and temperature fluctuations are only diffused.
A novel method was developed for the preparation of arborescent (dendritic graft) polymers, by successive grafting reactions of linear chain segments using alkyne-azide “click” chemistry coupling. A linear polystyrene substrate was thus randomly functionalized with acetylene functionalities, by acetylation and further reaction with propargyl bromide in the presence of potassium hydroxide and 18-crown-6 in toluene. The anionic polymerization of styrene was achieved with 6-tert-butyldimethylsiloxy-hexyllithium to obtain polystyrene with a protected hydroxyl chain end. Deprotection of the hydroxyl group, followed by conversion into tosyl and azide functionalities yielded the material serving as side chains in the grafting reactions. Coupling of the azide-terminated side chains with the acetylene-functionalized substrate in the presence of a Cu(I) catalyst proceeded in up to 93% yield. Additional cycles of substrate functionalization and side chain coupling led to arborescent polymers of generations G1 and G2, with low polydispersity indices (Mw/Mn≈ 1.1), in 60-84% yield. These polymers are characterized by a very compact structure, and molecular weights increasing geometrically over successive generations. A similar methodology was also shown to work for the synthesis of arborescent polybutadiene systems, using azide-functionalized substrates and alkyne-terminated side chains. The coupling reaction proceeded in up to 76% yield under optimized conditions for these systems.
The role of self generated magnetic fields in the transport of a heat wave following a nanosecond laser irradiation of a solid target is investigated. Magnetic fields are expected to localize the electron carrying the heat flux but at the same time are affected in their evolution by the heat flux itself. We performed simultaneous measurements of heat wave propagation velocity within the target and magnetic fields developing on the target surface. These were compared to results obtained by numerical magneto-hydrodynamic modeling, including self-generated B fields. The comparison shows that longitudinal heat flow is overestimated in the simulations. Similarly, but most notably, the radial expansion of the magnetic fields is underestimated by the modeling. The two are likely linked, the more pronounced radial drift of B-fields induces a rotation of heat flux in the radial direction, and corresponding longitudinal heat flux inhibition. This suggests the need for improving present modeling of self-generated magnetic fields evolution in high power laser-matter interaction.
The role of heterotrophic biofilm of water–sediment interface in detoxification processes was tested in abiotic and biotic conditions under laboratory conditions. Three toxicants, a herbicide (Diuron), a fungicide (Dimethomorph) and an insecticide (Chlorpyrifos-ethyl) have been tested in water percolating into columns reproducing hyporheic sediment. The detoxification processes were tested by comparing the water quality after 18 days of percolation with and without heterotrophic biofilm. Tested concentrations were 30 μg.L−1 of Diuron diluted in 0.1% dimethyl sulfoxide (DMSO), 2 μg.L−1 of Dimethomorph and 0.1 μg.L−1 of Chlorpyrifos-ethyl. To characterise the detoxification efficiency of the system, we performed genotoxicity bioassays in amphibian larvae and rotifers and measured the respiration and denitrification of sediments. Although the presence of biofilm increased the production of N-(3,4 dichlorophenyl)-N-(methyl)-urea, a metabolite of diuron, the toxicity did not decrease irrespective of the bioassay. In the presence of biofilm, Dimethomorph concentrations decreased compared with abiotic conditions, from 2 μg.L−1 to 0.4 μg.L−1 after 18 days of percolation. For both Dimethomorph and Chlorpyrifos-ethyl additions, assessment of detoxification level by the biofilm depended on the test used: detoxification effect was found with amphibian larvae bioassay and no detoxification was observed with the rotifer test. Heterotrophic biofilm exerts a major influence in the biochemical transformation of contaminants such as pesticides, suggesting that the interface between running water and sediment plays a role in self-purification of stream reaches.
Background: We aimed to develop a standardization method to pool data recorded on different activities of daily living (ADL) scales in order to reduce variability of functional outcome data from Alzheimer's disease (AD) clinical trials and to better evaluate the effect of donepezil treatment on function in patients with AD.
Methods: Based on pre-specified criteria, six studies were selected from among all donepezil clinical trials in AD. Individual items from nine ADL scales used in these trials were mapped to a standardized functional scale comprising 12 domains (six basic, six instrumental); scores were transformed to a 0–100 scale. External validation of this scale yielded a concordance rate of 90.8%. For each domain, mean change from baseline to 24 weeks in the placebo and donepezil groups was compared for the total population and for subgroups stratified by baseline disease severity. Study settings included outpatient, assisted living, and skilled nursing facilities. Participants comprised 2183 patients (donepezil, 1261; placebo; 922) with baseline Mini-mental State Examination (MMSE) scores 5–26.
Results: Significant treatment differences favoring donepezil were observed for five items (two instrumental and three basic). Patients with moderate AD at baseline (MMSE 10–17) demonstrated the greatest treatment effect.
Conclusion: Functional data were successfully pooled using standardizing methodology. A beneficial effect of donepezil treatment on function was demonstrated using this standardized functional scale. Similar analyses from studies with other anti-dementia drugs may help to determine the generalizability of these findings and potentially encourage use of functional assessment as a clinical tool.
Due to their particular properties (low emittance, short duration, and
large number density), the beams of multi-MeV protons generated during the
interaction of ultraintense (I > 1019 W/cm2)
short pulses with thin solid targets are suited for use as a particle
probe in laser-plasma experiments. When traversing a sample, the proton
density distribution is, in general, affected by collisional stopping,
scattering and deflections via electromagnetic fields, and each of these
effects can be used for diagnostic purposes. In particular, in the limit
of very thin targets, the proton beams represent a valuable diagnostic
tool for the detection of quasi-static electromagnetic fields. The proton
imaging and deflectometry techniques employ these beams, in a
point-projection imaging scheme, as an easily synchronizable diagnostic
tool in laser- plasma interactions, with high temporal and spatial
resolution. By providing diagnostic access to electro-magnetic field
distributions in dense plasmas, this novel diagnostics opens up to
investigation a whole new range of unexplored phenomena. Several transient
processes were investigated employing this technique, via the detection of
the associated electric fields. Examples provided in this paper include
the detection of pressure-gradient electric field in extended plasmas, and
the study of the electrostatic fields associated to the emission of MeV
proton beams in high-intensity laser-foil interactions.
The artistlike pictures of vortex flows presented here have been produced by the flow itself. The method of this “natural” flow visualization can be described briefly as follows: The working fluid is water mixed with some paste in order to increase the viscosity. Vortex flows are produced by pulling a stick or similar devices through the fluid or by injecting fluid through a nozzle into the working tank.
The flow visualization is performed in the following way: the surface of the fluid at rest is sparkled with oil paint of different colors diluted with some evaporating chemical. After the vortex structures have formed due to wakes or jets, a sheet of white paper is placed on the surface of the working fluid, where the oil color is attached to the paper immediately. The final results are artistlike paintings of vortex flows which exhibit a rich variety of flow structures.
Mixing in regular and chaotic flows
These photographs show the time evolution of two passive tracers in a low Reynolds number two-dimensional timeperiodic flow. The initial condition corresponds to two blobs of dye, green and orange, located below the free surface of a cavity filled with glycerine. The flow is induced by moving the top and bottom walls of the cavity while the other two walls are fixed. In this experiment the top wall moves from left to right and the bottom wall moves from right to left; both velocities are of the form Usin2(2πt/T), with the same U and the same period T, but with a phase shift of 90°.
Eye-covering play, deliberately closing or covering one's eyes during a play sequence, has been documented in various nonhuman primates. Some observers have suggested that eye-covering play involves pretending – acting as if one can't see, doesn't exist, or exists in some altered form (Cunningham, 1921; Hahn, 1982; de Waal, 1986b, 1989). Only one systematic study has been made of eye-covering play in nonhuman primates (Thierry, 1984) and no systematic attempts have been made to investigate the cognitive processes involved. We systematically studied eye-covering play in captive orangutans (Pongo pygmaeus) and Japanese macaques (Macaca fuscata) with the aim of assessing its cognitive implications in relation to pretending and imagination.
Cunningham (1921) was perhaps the first to describe eye-covering play in a nonhuman primate – in an immature lowland gorilla (Gorilla gorilla) who would shut his eyes tightly then run around knocking into furniture, which was interpreted as pretending to be blind. Eye-covering play has since been reported in all the great apes. Their play often takes the form of stumbling or groping about while “blind” (Hoyt, 1941; Harrisson, 1961, 1962; Lang, 1963; Gautier-Hion, 1971b; Goodall, 1971; Rensch, 1972; de Waal, 1986b, 1989). Occasionally they use objects to cover their eyes (Harrisson, 1962; Lang, 1963; Goodall, 1971; Rensch, 1972; de Waal, 1986b, 1989) and eye-covering play sometimes occurs as a social game (Hoyt, 1941; Harrisson, 1962).
This work reports the dynamic mechanical characterization of nanocomposites based on a poly(butyl acrylate) matrix filled with spherical particles of either polystyrene or silica both of diameter around 100 nm. A discrete numerical simulation, taking into account the microstructure and the nature of contact between reinforcing particles has been developed. This simulation enables to quantify the effect of interactions between filler particles on the elastic modulus, and in a more general sense, to clarify the concept of mechanical percolation. It gives results in very good agreement with experimental data.
A prerequisite to studying the specific interactions involved in the persistent transmission of luteoviruses such as the potato leafroll virus (PLRV) is the characterization of both the virus and its vectors. A range of techniques was used to assess genetic differentiation among 27 clones belonging to the Myzus persicae complex (M. persicae (Sulzer), M. antirrhinii (Macchiati) and M. nicotianaeBlackman) and showing different efficiencies in transmitting PLRV isolates. All M. persicae/M. nicotianae clones belonged to one of two karyotypes, both 2n = 12, either normal or carrying an autosomal translocation (A1,3), and all M. antirrhinii clones had 13 or 14 chromosomes. Amplified esterase 4 genes were detected by PCR–REN assay in M. persicae/M. nicotianae taxa, with gene expression being modified by methylation. Similarly, amplified E4 genes were revealed in M. antirrhinii but they all showed unmethylated. Two allozyme and 11 microsatellite loci discriminated 10 different genotypic classes among the 27 clones. Analysis of genetic relatedness between these genotypic classes revealed that M. nicotianae clones were very closely related to M. persicaeclones, whereas the genetic differentiation between M. antirrhinii and M. persicae was greater. The implications of these results for the taxonomic status of these genotypes within the complex, and the transmission of PLRV, are discussed.
Two billion years ago, natural fission reactions occured in the uranium ore deposit of Oklo (Gabon), mainly due to the high concentrations of fissile 235U. At that time, high uranium contents (40-60 % U) allowed reaching criticality when oxidised uranium bearing fluids met reduced fluids accompanying the migration of hydrocarbons. Natural fission reactors consist of a core made of uraninite crystals embedded in a clay matrix (mainly chlorites). The thickness of the clay layer range between few centimetres to 2 meters. Fission products are mostly located in the uraninite grains but newly crystallised minerals such as phosphate minerals, clays and metallic aggregates retain some proportions of migrated fissiogenic elements .
Natural fission reactors located in the uranium ore deposits of Oklo-Okélobondo and Bangombé (Gabon) are a unique case of natural nuclear waste disposal. The Reactor Zones (RZ) (up to fifteen) cores are made of 60% uranium (UO2) embedded in a clay matrix . The uraninites are depleted in 235U and contain fission products. Therefore, they are considered to be good analogues for spent nuclear fuel matrix . The aim of this work is to study the conditions of preservation over a long periode of time of the uraninites which have been sumitted to interraction with fluid having different oxidizing potential. For this purposes mineralogical (X-ray powder diffraction), chemical (electron microprobe) and oxygen isotopic analyses were performed on uraninites from various RZs.
Barry Reisberg: Alistair Burns, a researcher and a clinician, is very active in the International Psychogeriatric Association (IPA). He comes to us from the U.K., and will add a unique perspective. Sture Eriksson is from Umea, Sweden, and he is a geriatrician. He sees patients and he also has a research perspective and, more particularly for this meeting, he is the chairman ofthe IPA's research committee. Sandy Finkel is the current president of IPA. He's aclinician, he sees patients, and he does research both in nursing home settings and in outpatient, settings. Serge Gauthier is a neurologist. He comes to us from Montreal, Canada, and he is indeed a clinician and also a researcher and he is the director of the Canadian clinical trials consortium. Raymond Levy is the president-elect of the IPA. He is a professor at the Maudsley in London; he remains a clinician and he also has a truly longitudinal view of the field. Laurie Mallery is from Halifax. Nova Scoria. She's a geriatrician. She's very rnuch involved with patients, and she also has become involved in research and is familiar with research issues, and obviously lends a unique perspective.