Distinct genetic structure in populations of Chrysoperla externa (Hagen) (Neuroptera, Chrysopidae) shown by genetic markers ISSR and COI gene

Distinct genetic structure in populations of Chrysoperla externa (Hagen) (Neuroptera, Chrysopidae) shown by genetic markers ISSR and COI gene. Green lacewings are generalist predators, and the species Chrysoperla externa presents a great potential for use in biological control of agricultural pests due to its high predation and reproduction capacities, as well as its easy mass rearing in the laboratory. The adaptive success of a species is related to genetic variability, so that population genetic studies are extremely important in order to maximize success of the biological control. Thus, the present study used nuclear (Inter Simple Sequence Repeat - ISSR) and mitochondrial (Cytochrome Oxidase I - COI) molecular markers to estimate the genetic variability of 12 populations in the São Paulo State, Brazil, as well as the genetic relationships between populations. High levels of genetic diversity were observed for both markers, and the highest values of genetic diversity appear associated with municipalities that have the greatest areas of native vegetation. There was high haplotype sharing, and there was no correlation between the markers and the geographic distribution of the populations. The AMOVA indicated absence of genetic structure for the COI gene, suggesting that the sampled areas formed a single population unit. However, the great genetic differentiation among populations showed by ISSR demonstrates that these have been under differentiation after their expansion or may also reflect distinct dispersal behavior between males and females.

Schizophrenia connectivity: correlation between cognitive deficits and reduced thalamo-cortical fibers

Introduction: Schizophrenia is associated with multiple neuropsychological dysfunctions, such as disturbances of attention, memory, perceptual functioning, concept formation and executive processes. These cognitive functions are reported to depend on the integrity of the prefrontal and thalamo-prefrontal circuits. Multiple lines of evidence suggest that schizophrenia is related to abnormalities in neural circuitry and impaired structural connectivity. Here, we report a preliminary case-control study that showed a correlation between thalamo-frontal connections and several cognitive functions known to be impaired in schizophrenia. Materials and Methods: We investigated 9 schizophrenic patients (DSM IV criteria, Diagnostic Interview for Genetic Studies) and 9 age and sex matched control subjects. We obtained from each volunteer a DT-MRI dataset (3 T, _ _ 1,000 s/mm2), and a high resolution anatomic T1. The thalamo- frontal tracts are simulated with DTI tractography on these dataset, a method allowing inference of the main neural fiber tracks from Diffusion MRI data. In order to see an eventual correlation with the thalamo-frontal connections, every subject performs a battery of neuropsychological tests including computerized tests of attention (sustained attention, selective attention and reaction time), working memory tests (Plane test and the working memory sub-tests of the Wechsler Adult Intelligence Scale), a executive functioning task (Tower of Hanoï) and a test of visual binding abilities. Results: In a pilot case-control study (patients: n _ 9; controls: n _ 9), we showed that this methodology is appropriate and giving results in the excepted range. Considering the relation of the connectivity density and the neuropsychological data, a correlation between the number of thalamo- frontal fibers and the performance in the Tower of Hanoï was observed in the patients (Pearson correlation, r _ 0.76, p _ 0.05) but not in control subjects. In the most difficult item of the test, the least number of fibers corresponds to the worst performance of the test (fig. 2, number of supplementary movements of the elements necessary to realize the right configuration). It's interesting to note here that in an independent study, we showed that schizophrenia patients (n _ 32) perform in the most difficult item of the Tower of Hanoï (Mann-Whitney, p _ 0.005) significantly worse than control subjects (n _ 29). This has been observed in several others neuropsychological studies. Discussion: This pilot study of schizophrenia patients shows a correlation between the number of thalam-frontal fibers and the performance in the Tower of Hanoï, which is a planning and goal oriented actions task known to be associated with frontal dysfonction. This observation is consistent with the proposed impaired connectivity in schizophrenia. We aim to pursue the study with a larger sample in order to determine if other neuropsychological tests may be associated with the connectivity density.

Dynamic properties of human brain structure: learning-related changes in cortical areas and associated fiber connections.

Recent findings in neuroscience suggest that adult brain structure changes in response to environmental alterations and skill learning. Whereas much is known about structural changes after intensive practice for several months, little is known about the effects of single practice sessions on macroscopic brain structure and about progressive (dynamic) morphological alterations relative to improved task proficiency during learning for several weeks. Using T1-weighted and diffusion tensor imaging in humans, we demonstrate significant gray matter volume increases in frontal and parietal brain areas following only two sessions of practice in a complex whole-body balancing task. Gray matter volume increase in the prefrontal cortex correlated positively with subject's performance improvements during a 6 week learning period. Furthermore, we found that microstructural changes of fractional anisotropy in corresponding white matter regions followed the same temporal dynamic in relation to task performance. The results make clear how marginal alterations in our ever changing environment affect adult brain structure and elucidate the interrelated reorganization in cortical areas and associated fiber connections in correlation with improvements in task performance.

Residual Stress Measurement on a MEMS Structure With High-Spatial Resolution

A new approach to the local measurement of residual stress in microstructures is described in this paper. The presented technique takes advantage of the combined milling-imaging features of a focused ion beam (FIB) equipment to scale down the widely known hole drilling method. This method consists of drilling a small hole in a solid with inherent residual stresses and measuring the strains/displacements caused by the local stress release, that takes place around the hole. In the presented case, the displacements caused by the milling are determined by applying digital image correlation (DIC) techniques to high resolution micrographs taken before and after the milling process. The residual stress value is then obtained by fitting the measured displacements to the analytical solution of the displacement fields. The feasibility of this approach has been demonstrated on a micromachined silicon nitride membrane showing that this method has high potential for applications in the field of mechanical characterization of micro/nanoelectromechanical systems.

Effects of prior hydrogenation on the structure and properties of thermally nanocrystallized silicon layers

Nanocrystalline silicon layers have been obtained by thermal annealing of films sputtered in various hydrogen partial pressures. The as-deposited and crystallized films were investigated by infrared, Raman, x-ray diffraction, electron microscopy, and optical absorption techniques. The obtained data show evidence of a close correlation between the microstructure and properties of the processed material, and the hydrogen content in the as-grown deposit. The minimum stress deduced from Raman was found to correspond to the widest band gap and to a maximum hydrogen content in the basic unannealed sample. Such a structure relaxation seems to originate from the so-called "chemical annealing" thought to be due to Si-H2 species, as identified by infrared spectroscopy. The variation of the band gap has been interpreted in terms of the changes in the band tails associated with the disorder which would be induced by stress. Finally, the layers originally deposited with the highest hydrogen pressure show a lowest stress-which does not correlate with the hydrogen content and the optical band gap¿and some texturing. These features are likely related to the presence in these layers of a significant crystalline fraction already before annealing.

Impact of incorrect assumptions on the covariance structure of random effects and/or residuals in nonlinear mixed models for repeated measures data

In this paper we analyse, using Monte Carlo simulation, the possible consequences of incorrect assumptions on the true structure of the random effects covariance matrix and the true correlation pattern of residuals, over the performance of an estimation method for nonlinear mixed models. The procedure under study is the well known linearization method due to Lindstrom and Bates (1990), implemented in the nlme library of S-Plus and R. Its performance is studied in terms of bias, mean square error (MSE), and true coverage of the associated asymptotic confidence intervals. Ignoring other criteria like the convenience of avoiding over parameterised models, it seems worst to erroneously assume some structure than do not assume any structure when this would be adequate.

Exchange-correlation effects on quantum wires with spin-orbit interactions under the influence of in-plane magnetic fields.

Within the noncollinear local spin-density approximation, we have studied the ground state structure of a parabolically confined quantum wire submitted to an in-plane magnetic field, including both Rashba and Dresselhaus spin-orbit interactions. We have explored a wide range of linear electronic densities in the weak (strong) coupling regimes that appear when the ratio of spin-orbit to confining energy is small (large). These results are used to obtain the conductance of the wire. In the strong coupling limit, the interplay between the applied magnetic field¿irrespective of the in-plane direction, the exchange-correlation energy, and the spin-orbit energy-produces anomalous plateaus in the conductance vs linear density plots that are otherwise absent, or washes out plateaus that appear when the exchange-correlation energy is not taken into account.

Energy and structure of dilute hard- and soft-sphere gases

The energy and structure of dilute hard- and soft-sphere Bose gases are systematically studied in the framework of several many-body approaches, such as the variational correlated theory, the Bogoliubov model, and the uniform limit approximation, valid in the weak-interaction regime. When possible, the results are compared with the exact diffusion Monte Carlo ones. Jastrow-type correlation provides a good description of the systems, both hard- and soft-spheres, if the hypernetted chain energy functional is freely minimized and the resulting Euler equation is solved. The study of the soft-sphere potentials confirms the appearance of a dependence of the energy on the shape of the potential at gas paremeter values of x~0.001. For quantities other than the energy, such as the radial distribution functions and the momentum distributions, the dependence appears at any value of x. The occurrence of a maximum in the radial distribution function, in the momentum distribution, and in the excitation spectrum is a natural effect of the correlations when x increases. The asymptotic behaviors of the functions characterizing the structure of the systems are also investigated. The uniform limit approach is very easy to implement and provides a good description of the soft-sphere gas. Its reliability improves when the interaction weakens.

SPATIAL CORRELATION BETWEEN PHYSICAL PROPERTIES OF SOIL AND WEEDS IN TWO MANAGEMENT SYSTEMS

The spatial correlation between soil properties and weeds is relevant in agronomic and environmental terms. The analysis of this correlation is crucial for the interpretation of its meaning, for influencing factors such as dispersal mechanisms, seed production and survival, and the range of influence of soil management techniques. This study aimed to evaluate the spatial correlation between the physical properties of soil and weeds in no-tillage (NT) and conventional tillage (CT) systems. The following physical properties of soil and weeds were analyzed: soil bulk density, macroporosity, microporosity, total porosity, aeration capacity of soil matrix, soil water content at field capacity, weed shoot biomass, weed density, Commelina benghalensis density, and Bidens pilosa density. Generally, the ranges of the spatial correlations were higher in NT than in CT. The cross-variograms showed that many variables have a structure of combined spatial variation and can therefore be mapped from one another by co-kriging. This combined variation also allows inferences about the physical and biological meanings of the study variables. Results also showed that soil management systems influence the spatial dependence structure significantly.

Static and dynamic structure of liquid metals: Role of the different parts of the interaction potential

The influence of different parts of the interaction potential on the microscopic behavior of simple liquid metals is investigated by molecular dynamics simulation. The role of the soft-core repulsive, short-range attractive, and long-range oscillatory forces on the properties of liquid lithium close to the triple point is analyzed by comparing the results from simulations of identical systems but truncating the potential at different distances. Special attention is paid to dynamic collective properties such as the dynamic structure factors, transverse current correlation functions, and transport coefficients. It is observed that, in general, the effects of the short-range attractive forces are important. On the contrary, the influence of the oscillatory long-range interactions is considerably less, being the most pronounced for the dynamic structure factor at long wavelengths. The results of this work suggest that the influence of the attractive forces becomes less significant when temperature and density increase.

Nurture versus nature: long-term impact of forced right-handedness on structure of pericentral cortex and basal ganglia.

Does a conflict between inborn motor preferences and educational standards during childhood impact the structure of the adult human brain? To examine this issue, we acquired high-resolution T1-weighted magnetic resonance scans of the whole brain in adult "converted" left-handers who had been forced as children to become dextral writers. Analysis of sulcal surfaces revealed that consistent right- and left-handers showed an interhemispheric asymmetry in the surface area of the central sulcus with a greater surface contralateral to the dominant hand. This pattern was reversed in the converted group who showed a larger surface of the central sulcus in their left, nondominant hemisphere, indicating plasticity of the primary sensorimotor cortex caused by forced use of the nondominant hand. Voxel-based morphometry showed a reduction of gray matter volume in the middle part of the left putamen in converted left-handers relative to both consistently handed groups. A similar trend was found in the right putamen. Converted subjects with at least one left-handed first-degree relative showed a correlation between the acquired right-hand advantage for writing and the structural changes in putamen and pericentral cortex. Our results show that a specific environmental challenge during childhood can shape the macroscopic structure of the human basal ganglia. The smaller than normal putaminal volume differs markedly from previously reported enlargement of cortical gray matter associated with skill acquisition. This indicates a differential response of the basal ganglia to early environmental challenges, possibly related to processes of pruning during motor development.

Electronic and magnetic structure of LaMnO3 from hybrid periodic density-functional theory

The electronic and magnetic structures of the LaMnO3 compound have been studied by means of periodic calculations within the framework of spin polarized hybrid density-functional theory. In order to quantify the role of approximations to electronic exchange and correlation three different hybrid functionals have been used which mix nonlocal Fock and local Dirac-Slater exchange. Periodic Hartree-Fock results are also reported for comparative purposes. The A-antiferromagnetic ground state is properly predicted by all methods including Hartree-Fock exchange. In general, the different hybrid methods provide a rather accurate description of the band gap and of the two magnetic coupling constants, strongly suggesting that the corresponding description of the electronic structure is also accurate. An important conclusion emerging from this study is that the nature of the occupied states near the Fermi level is intermediate between the Hartree-Fock and local density approximation descriptions with a comparable participation of both Mn and O states.

The four- vs. alternative six-factor structure of the French WISC-IV: Comparison using confirmatory factor analyses

Exploratory and confirmatory factor analyses reported in the French technical manual of the WISC-IV provides evidence supporting a structure with four indices: Verbal Comprehension (VCI), Perceptual Reasoning (PRI), Working Memory (WMI), and Processing Speed (PSI). Although the WISC-IV is more attuned to contemporary theory, it is still not in total accordance with the dominant theory: the Cattell-Horn-Carroll (CHC) theory of cognitive ability. This study was designed to determine whether the French WISC-IV is better described with the four-factor solution or whether an alternative model based on the CHC theory is more appropriate. The intercorrelations matrix reported in the French technical manual was submitted to confirmatory factor analysis. A comparison of competing models suggests that a model based on the CHC theory fits the data better than the current WISC-IV structure. It appears that the French WISC-IV in fact measures six factors: crystallized intelligence (Gc), fluid intelligence (Gf), short-term memory (Gsm), processing speed (Gs), quantitative knowledge (Gq), and visual processing (Gv). We recommend that clinicians interpret the subtests of the French WISC-IV in relation to this CHC model in addition to the four indices.

Correlation of photodynamic activity and fluorescence signaling for free and pegylated mTHPC in mesothelioma xenografts

Rapport de synthèse : Introduction : Les premières applications cliniques de la thérapie photodynamique (PDT) remontent à plus d'une vingtaine d'années. Basée sur l'activation d'un médicament photosensibilisateur par une source lumineuse à une longueur d'onde spécifique, la PDT permet la destruction sélective de tissus contenant le produit actif. Ce procédé a été expérimenté dans le traitement de cancers en raison de la propriété du médicament à se concentrer dans les tumeurs tout en épargnant les structures normales contigües. Cependant, les photosensibilisateurs utilisés jusqu'à ce jour n'ont pas démontré une accumulation exclusive dans les tissus néoplasiques mais également dans les structures saines avoisinantes induisant une destruction tissulaire non sélective. Notamment, d'importantes complications ont été rapportées suite à l'utilisation de la PDT dans la cavité thoracique après la résection de mésothéliomes pleuraux, et ce malgré l'arrivée de photosensibilisateurs de secondes générations. De ce fait, plusieurs études expérimentales ont été menées afin d'améliorer la sélectivité tumorale du médicament en modulant différentes conditions de traitement et en modifiant la structure du photosensibilisateur par pégylation. Le but de cette étude expérimentale est de corréler l'activité photodynamique, la phototoxicité et la distribution du m-tetrahydroxyphenylchlorin (mTHPC) et de sa forme pégylée, le PEG-mTHPC. De ce fait, un modèle de souris nues porteur de xenogreffes de mésothéliome humain a été utilisé pour étudier les deux photosensibilisateurs. De récents travaux avec ce modèle ont montré que la mesure de la concentration tissulaire du mTHPC et de sa forme pégylée par HPLC restait limitée afin de prédire l'activité photodynamique. De ce fait, nous pensons que les mesures de fluorescence peuvent être plus appropriée. Le signalement fluorescent est mesuré dans le tissu tumoral et dans une région contrôle de la peau afin d'étudier la distribution et l'intensité des deux sensibilisateurs. Méthode : Des souris nues (cd1nu/nu mice) de 8 semaines ont été transplantées avec des fragments de mésothéliome malin humain (H-meso-1). Ces derniers ont été obtenus à partir d'une suspension cellulaire. Au moins trois passages ont été faits dans les animaux, avant que le traitement soit initié. Deux groupes de 6 souris chacun ont été utilisés pour l'injection intraveineuse par la queue du mTHPC à 0.15 mg/kg et du PEG-mTHPC à dose équimolaire. Après trois jour, la tumeur ainsi qu'une région contrôle de la cuisse ont été illuminées sur une surface d'un diamètre de 1.2 cm et pendant 133 secondes avec un laser à une longueur d'onde à 652 nm (fluence 20 J/cm2, fluence rate 150 mW/cm2). Les animaux ont été ensuite sacrifiés 72 heures après l'illumination. L'étendue de la nécrose tumorale et de la région contrôle ont été déterminées en aveugle par histomorphometrie par un pathologue (HJA). La fluorescence microscopique a été évaluée dans 12 souris à une concentration de 0.15 et 0.5 mg/kg pour le mTHPC, et à doses équimolaires pour le PEG-mTHPC. Trois animaux ont été injectés avec le mTHPC à 0.15 mg/kg, 3 autres à dose équimolaire avec la forme pégylée et 6 souris avec le mTHPC à 0.5 mg/kg et à dose équimolaire. Les animaux ont été sacrifiés 72 heures après injection. L'intensité fluorescente des sensibilisateurs a été mesurée dans la tumeur et la région contrôle. Suite à cela, les coupes ont été fixées par H&E et superposées aux images fluorescentes, afin de localiser la distribution des deux photosensibilisateurs dans les différents compartiments tissulaires. Six souris transplantées n'ayant ni été injectées avec les sensibilisateurs ou illuminées ont servi de groupe contrôle. Résultats : Trois jours après l'illumination, la PDT provoque une nécrose tumorale de 10 ±5.4 mm2 pour le mTHPC à 0.15mg/kg et 5.2 ± 4.6 mm2 pour sa forme pégylée à dose équimolaire. Cependant, la nécrose tumorale induite par les deux formulations du sensibilisateur est significativement plus élevée que dans le groupe contrôle (0.33 ± 0.58 mm2) (P=0.02). Toutefois, le mTHPC pégylé provoque une photosensibilité cutanée moins importante que la forme non-pegylée. Dans les deux groupes, aucune nécrose n'a été observée dans la cuisse des animaux. Trois jours après l'injection du mTHPC et de la forme pégylée à 0.15 mg/kg, aucune activité fluorescente n'a été détectée. Cependant, à 0.5 mg/kg, la fluorescence microscopique révèle une distribution hétérogène des deux photo-sensibilisateurs dans le tissu tumoral avec une accumulation prédominante dans les régions peri-vasculaires. Les deux médicaments montrent une distribution intracellulaire homogène dans le cytoplasme et une absence de signalement dans le nucleus. La mesure de l'intensité fluorescente du mTHPC à 0.5mg/kg ne montre pas de différence significative entre le tissu tumoral et la région contrôle. Par contre, le PEG-mTHPC montre une intensité fluorescente supérieure dans le tissu tumoral que dans la peau (ratio tumeur- peau 0.94 pour le mTHPC et 1.73 pour le PEG-mTHPC). Conclusion : L'utilisation du mTHPC à 0.15mg/kg induit une nécrose tumorale similaire à celle du PEG-mTHPC à dose équimolaire. Cependant, ce dernier démontre une photo-toxicité plus atténuée de la peau. La fluorescence microscopique permet de localiser les deux sensibilisateurs dans les différents compartiments tissulaires à partir d'une dose de 0.5 mg/kg. Le PEG-mTHPC induit un signalement fluorescent supérieur dans le tissu tumoral par rapport à la peau. La mesure du signalement fluorescent a le potentiel de prédire l'activité photodynamique du mTHPC et de sa forme pégylée dans les xénogreffes de mésothéliome humain dans un modèle de souris nue.

Genotype-phenotype interactions in primary dystonias revealed by differential changes in brain structure.

Our understanding of how genotype determines phenotype in primary dystonia is limited. Familial young-onset primary dystonia is commonly due to the DYT1 gene mutation. A critical question, given the 30% penetrance of clinical symptoms in DYT1 mutation carriers, is why the same genotype leads to differential clinical expression and whether non-DYT1 adult-onset primary dystonia, with and without family history share pathophysiological mechanisms with DYT1 dystonia. This study examines the relationship between dystonic phenotype and the DYT1 gene mutation by monitoring whole-brain structure using voxel-based morphometry. We acquired magnetic resonance imaging data of symptomatic and asymptomatic DYT1 mutation carriers, of non-DYT1 primary dystonia patients, with and without family history and control subjects with normal DYT1 alleles. By crossing the factors genotype and phenotype we demonstrate a significant interaction in terms of brain anatomy confined to the basal ganglia bilaterally. The explanation for this effect differs according to both gene and dystonia status: non-DYT1 adult-onset dystonia patients and asymptomatic DYT1 carriers have significantly larger basal ganglia compared to healthy subjects and symptomatic DYT1 mutation carriers. There is a significant negative correlation between severity of dystonia and basal ganglia size in DYT1 mutation carriers. We propose that differential pathophysiological and compensatory mechanisms lead to brain structure changes in non-DYT1 primary adult-onset dystonias and DYT1 gene carriers. Given the range of age of onset, there may be differential genetic modulation of brain development that in turn determines clinical expression. Alternatively, a DYT1 gene dependent primary defect of motor circuit development may lead to stress-induced remodelling of the basal ganglia and hence dystonia.