Sex differences: From mental rotation to object location memory, an ERP study

Sex differences in cognition have been largely investigated. The most consistent sex differences favoring females are observed in object location memory involving the left hemisphere whereas the most consistent sex differences favoring males are observed in tasks that require mental rotation involving the right hemisphere. Here we used a task involving these two abilities to see the impact of mental rotation on object location memory. To that end we used a combination of behavioral and event-related potential (ERP) electroencephalography (EEG) measures.A computer screen displayed a square frame of 4 pairs of images (a "teddy" bear, a shoe, an umbrella and a lamp) randomly arranged around a central fixation cross. After a 10-second interval for memorization, images disappeared and were replaced by a test frame with no image but a random pair of two locations marked in black. In addition, this test frame was randomly displayed either in the original orientation (0° rotation) or in the rotated one (90° clockwise - CW - or 90° counterclockwise - CCW). Preceding the test frame, an arrow indicating the presence or the absence of rotation of the frame was displayed on the screen. The task of the participants (15 females and 15 males) was to determine if two marked locations corresponded or not to a pair of identical images. Each response was followed by feedback.Findings showed no significant sex differences in the performance of the original orientation. In comparison with this position, the rotation of the frame produced an equal decrease of male and female performance. In addition, this decrease was significantly higher when the rotation of the frame was in a CCW direction. We further assessed the ERP when the arrow indicated the direction of rotation as stimulus-onset, during four time windows representing major components C1, P1, N1 and N2. Although no sex differences were observed in performance, brain activities differed according to sex. Enhanced amplitudes were found for the CCW compared to CW rotation over the right posterior areas for the P1, N1 and N2 components for men as well as for women. Major topographical differences related to sex were measured for the CW rotation condition as marked lateralized amplitude: left-hemisphere amplitude larger than right one was measured during P1 time range for men. These similar patterns prolonged from P1 to N1 for women. Early distinctions were found in interaction with sex between CCW and CW waveform amplitudes, expressing over anterior electrode sites during C1 time range (0-50 ms post-stimulus).In conclusion (i) women do not outperform men in object location memory in this study (absence of rotation condition); (ii) mental rotation, in particular the direction of rotation, influences performance on object location memory; (iii) CCW rotation is associated with activity in the right parietal hemisphere whereas the CW rotation involves the left parietal hemisphere; (iv) this last effect is less pronounced in males, which could explain why greater involvement of right parietal areas in men and of bilateral posterior areas in women is generally reported in mental rotation tasks; and (v) the early distinctions between both directions of rotation located over anterior sites could be related to sex differences in their respective involvement of control mechanisms.

Different internalization properties of the alpha1a- and alpha1b-adrenergic receptor subtypes: the potential role of receptor interaction with beta-arrestins and AP50.

The internalization properties of the alpha1a- and alpha1b-adrenergic receptors (ARs) subtypes transiently expressed in human embryonic kidney (HEK) 293 cells were compared using biotinylation experiments and confocal microscopy. Whereas the alpha1b-AR displayed robust agonist-induced endocytosis, the alpha1a-AR did not. Constitutive internalization of the alpha1a-AR was negligible, whereas the alpha1b-AR displayed significant constitutive internalization and recycling. We investigated the interaction of the alpha1-AR subtypes with beta-arrestins 1 and 2 as well as with the AP50 subunit of the clathrin adaptor complex AP2. The results from both coimmunoprecipitation experiments and beta-arrestin translocation assays indicated that the agonistinduced interaction of the alpha1a-AR with beta-arrestins was much weaker than that of the alpha1b-AR. In addition, the alpha1a-AR did not bind AP50. The alpha1b-AR mutant M8, lacking the main phosphorylation sites in the receptor C tail, was unable to undergo endocytosis and was profoundly impaired in binding beta-arrestins despite its binding to AP50. In contrast, the alpha1b-AR mutant DeltaR8, lacking AP50 binding, bound beta-arrestins efficiently, and displayed delayed endocytosis. RNA interference showed that beta-arrestin 2 plays a prominent role in alpha1b-AR endocytosis. The findings of this study demonstrate differences in internalization between the alpha1a- and alpha1b-AR and provide evidence that the lack of significant endocytosis of the alpha1a-AR is linked to its poor interaction with beta-arrestins as well as with AP50. We also provide evidence that the integrity of the phosphorylation sites in the C tail of the alpha1b-AR is important for receptor/beta-arrestin interaction and that this interaction is the main event triggering receptor internalization.

Source wavelet estimation for waveform inversion of crosshole georadar data

AbstractFor a wide range of environmental, hydrological, and engineering applications there is a fast growing need for high-resolution imaging. In this context, waveform tomographic imaging of crosshole georadar data is a powerful method able to provide images of pertinent electrical properties in near-surface environments with unprecedented spatial resolution. In contrast, conventional ray-based tomographic methods, which consider only a very limited part of the recorded signal (first-arrival traveltimes and maximum first-cycle amplitudes), suffer from inherent limitations in resolution and may prove to be inadequate in complex environments. For a typical crosshole georadar survey the potential improvement in resolution when using waveform-based approaches instead of ray-based approaches is in the range of one order-of- magnitude. Moreover, the spatial resolution of waveform-based inversions is comparable to that of common logging methods. While in exploration seismology waveform tomographic imaging has become well established over the past two decades, it is comparably still underdeveloped in the georadar domain despite corresponding needs. Recently, different groups have presented finite-difference time-domain waveform inversion schemes for crosshole georadar data, which are adaptations and extensions of Tarantola's seminal nonlinear generalized least-squares approach developed for the seismic case. First applications of these new crosshole georadar waveform inversion schemes on synthetic and field data have shown promising results. However, there is little known about the limits and performance of such schemes in complex environments. To this end, the general motivation of my thesis is the evaluation of the robustness and limitations of waveform inversion algorithms for crosshole georadar data in order to apply such schemes to a wide range of real world problems.One crucial issue to making applicable and effective any waveform scheme to real-world crosshole georadar problems is the accurate estimation of the source wavelet, which is unknown in reality. Waveform inversion schemes for crosshole georadar data require forward simulations of the wavefield in order to iteratively solve the inverse problem. Therefore, accurate knowledge of the source wavelet is critically important for successful application of such schemes. Relatively small differences in the estimated source wavelet shape can lead to large differences in the resulting tomograms. In the first part of my thesis, I explore the viability and robustness of a relatively simple iterative deconvolution technique that incorporates the estimation of the source wavelet into the waveform inversion procedure rather than adding additional model parameters into the inversion problem. Extensive tests indicate that this source wavelet estimation technique is simple yet effective, and is able to provide remarkably accurate and robust estimates of the source wavelet in the presence of strong heterogeneity in both the dielectric permittivity and electrical conductivity as well as significant ambient noise in the recorded data. Furthermore, our tests also indicate that the approach is insensitive to the phase characteristics of the starting wavelet, which is not the case when directly incorporating the wavelet estimation into the inverse problem.Another critical issue with crosshole georadar waveform inversion schemes which clearly needs to be investigated is the consequence of the common assumption of frequency- independent electromagnetic constitutive parameters. This is crucial since in reality, these parameters are known to be frequency-dependent and complex and thus recorded georadar data may show significant dispersive behaviour. In particular, in the presence of water, there is a wide body of evidence showing that the dielectric permittivity can be significantly frequency dependent over the GPR frequency range, due to a variety of relaxation processes. The second part of my thesis is therefore dedicated to the evaluation of the reconstruction limits of a non-dispersive crosshole georadar waveform inversion scheme in the presence of varying degrees of dielectric dispersion. I show that the inversion algorithm, combined with the iterative deconvolution-based source wavelet estimation procedure that is partially able to account for the frequency-dependent effects through an "effective" wavelet, performs remarkably well in weakly to moderately dispersive environments and has the ability to provide adequate tomographic reconstructions.

Comparison of three acellular tests for assessing the oxidation potential of nanomaterials

Great effort is put into developing reliable, predictive, high-throughput, and low-cost screening approaches for the toxicity evaluation of ambient and manufactured nanoparticles (NP). These tests often consider oxidative reactivity, as oxidative stress is a well-documented pathway in particle toxicology. Based on a panel of six carbonaceous and five metal/metal oxide (Me/MeOx) nanoparticles, we: (i) compared the specifications (linearity, detection limits, repeatability) of three acellular reactivity tests using either dithiothreitol (DTT assay), dichlorofluorescein (DCFH assay), or ascorbic acid (AA-assay) as the reducing agent; and (ii) evaluated which physicochemical properties were important for explaining the observed reactivity. The selected AA assay was found to be neither sensitive nor robust enough to be retained. For the other tests, the surface properties of carbonaceous NP were of utmost importance for explaining their reactivity. In particular, the presence of "strongly reducing" surface functions explained most of its DCFH reactivity and a large part of its DTT reactivity. For the selected Me/MeOx, a different picture emerged. Whereas all particles were able to oxidize DCFH, dissolution and complexation processes could additionally influence the measured reactivity, as observed using the DTT assay. This study suggests that a combination of the DTT and DCFH assays provides complementary information relative to the quantification of the oxidative capacity of NP.

Sex differences: From mental rotation to object location memory, an ERP study

Sex differences in cognition have been largely investigated. The most consistent sex differences favoring females are observed in object location memory involving the left hemisphere whereas the most consistent sex differences favoring males are observed in tasks that require mental rotation involving the right hemisphere. Here we used a task involving these two abilities to see the impact of mental rotation on object location memory. To that end we used a combination of behavioral and event-related potential (ERP) electroencephalography (EEG) measures.A computer screen displayed a square frame of 4 pairs of images (a "teddy" bear, a shoe, an umbrella and a lamp) randomly arranged around a central fixation cross. After a 10-second interval for memorization, images disappeared and were replaced by a test frame with no image but a random pair of two locations marked in black. In addition, this test frame was randomly displayed either in the original orientation (0° rotation) or in the rotated one (90° clockwise - CW - or 90° counterclockwise - CCW). Preceding the test frame, an arrow indicating the presence or the absence of rotation of the frame was displayed on the screen. The task of the participants (15 females and 15 males) was to determine if two marked locations corresponded or not to a pair of identical images. Each response was followed by feedback.Findings showed no significant sex differences in the performance of the original orientation. In comparison with this position, the rotation of the frame produced an equal decrease of male and female performance. In addition, this decrease was significantly higher when the rotation of the frame was in a CCW direction. We further assessed the ERP when the arrow indicated the direction of rotation as stimulus-onset, during four time windows representing major components C1, P1, N1 and N2. Although no sex differences were observed in performance, brain activities differed according to sex. Enhanced amplitudes were found for the CCW compared to CW rotation over the right posterior areas for the P1, N1 and N2 components for men as well as for women. Major topographical differences related to sex were measured for the CW rotation condition as marked lateralized amplitude: left-hemisphere amplitude larger than right one was measured during P1 time range for men. These similar patterns prolonged from P1 to N1 for women. Early distinctions were found in interaction with sex between CCW and CW waveform amplitudes, expressing over anterior electrode sites during C1 time range (0-50 ms post-stimulus).In conclusion (i) women do not outperform men in object location memory in this study (absence of rotation condition); (ii) mental rotation, in particular the direction of rotation, influences performance on object location memory; (iii) CCW rotation is associated with activity in the right parietal hemisphere whereas the CW rotation involves the left parietal hemisphere; (iv) this last effect is less pronounced in males, which could explain why greater involvement of right parietal areas in men and of bilateral posterior areas in women is generally reported in mental rotation tasks; and (v) the early distinctions between both directions of rotation located over anterior sites could be related to sex differences in their respective involvement of control mechanisms.

Lineage potential, plasticity and environmental reprogramming of epithelial stem/progenitor cells.

Recent evidence supports and reinforces the concept that environmental cues may reprogramme somatic cells and change their natural fate. In the present review, we concentrate on environmental reprogramming and fate potency of different epithelial cells. These include stratified epithelia, such as the epidermis, hair follicle, cornea and oesophagus, as well as the thymic epithelium, which stands alone among simple and stratified epithelia, and has been shown recently to contain stem cells. In addition, we briefly discuss the pancreas as an example of plasticity of intrinsic progenitors and even differentiated cells. Of relevance, examples of plasticity and fate change characterize pathologies such as oesophageal metaplasia, whose possible cell origin is still debated, but has important implications as a pre-neoplastic event. Although much work remains to be done in order to unravel the full potential and plasticity of epithelial cells, exploitation of this phenomenon has already entered the clinical arena, and might provide new avenues for future cell therapy of these tissues.

Thyroid hormone in biodegradable nerve guides stimulates sciatic nerve regeneration: a potential therapeutic approach for human peripheral nerve injuries.

It has been already demonstrated that thyroid hormone (T3) is one of the most important stimulating factors in peripheral nerve regeneration. We have recently shown that local administration of T3 in silicon tubes at the level of the transected rat sciatic nerve enhanced axonal regeneration and improved functional recovery. Silicon, however, cannot be used in humans because it causes a chronic inflammatory reaction. Therefore, in order to provide future clinical applications of thyroid hormone in human peripheral nerve lesions, we carried out comparative studies on the regeneration of transected rat sciatic nerve bridged either by biodegradable P(DLLA-(-CL) or by silicon nerve guides, both guides filled with either T3 or phosphate buffer. Our macroscopic observation revealed that 85% of the biodegradable guides allowed the expected regeneration of the transected sciatic nerve. The morphological, morphometric and electrophysiological analysis showed that T3 in biodegradable guides induces a significant increase in the number of myelinated regenerated axons (6862 +/- 1831 in control vs. 11799 +/- 1163 in T3-treated). Also, T3 skewed the diameter of myelinated axons toward larger values than in controls. Moreover, T3 increases the compound muscle action potential amplitude of the flexor and extensor muscles of the treated rats. This T3 stimulation in biodegradable guides was equally well to that obtained by using silicone guides. In conclusion, the administration of T3 in biodegradable guides significantly improves sciatic nerve regeneration, confirming the feasibility of our technique to provide a serious step towards future clinical application of T3 in human peripheral nerve injuries.

Scaled and adjusted restricted tests in multi-sample analysis of moment structures

We extend to score, Wald and difference test statistics the scaled and adjusted corrections to goodness-of-fit test statistics developed in Satorra and Bentler (1988a,b). The theory is framed in the general context of multisample analysis of moment structures, under general conditions on the distribution of observable variables. Computational issues, as well as the relation of the scaled and corrected statistics to the asymptotic robust ones, is discussed. A Monte Carlo study illustrates thecomparative performance in finite samples of corrected score test statistics.

A house price index defined in the potential outcomes framework

Current methods for constructing house price indices are based on comparisons of sale prices of residential properties sold two or more times and on regression of the sale prices on the attributes of the properties and of their locations. The two methods have well recognised deficiencies, selection bias and model assumptions, respectively. We introduce a new method based on propensity score matching. The average house prices for two periods are compared by selecting pairs of properties, one sold in each period, that are as similar on a set of available attributes (covariates) as is feasible to arrange. The uncertainty associated with such matching is addressed by multiple imputation, framing the problem as involving missing values. The method is applied to aregister of transactions ofresidential properties in New Zealand and compared with the established alternatives.

Study of the mechanisms regulating the proliferative potential of human CD8+T lymphocytes over-expressing telomerase reverse transcriptase (hTERT)

Résumé La plupart des cellules issues du sang ont une durée de vie limitée. Dans les cellules somatiques humaines, y incluant les lymphocytes T, la taille des télomères diminue progressivement à chaque division cellulaire, pouvant aboutir à des instabilités chromosomiques. L'expression ectopique du gène de la transcriptase réverse de la télomérase (hTERT) dans les cellules restaure l'activité de la télomérase, et permet un rallongement de leur vie réplicative. Malgré l'absence de signes caractéristiques de transformation, nous ne savons pas encore si les cellules somatiques qui surexpriment hTERT sont physiologiquement indiscernables des cellules normales. Certaines études récentes proposent que la télomérase joue plusieurs rôles additionnels dans d'autres phénomènes biologiques tels que la réparation de l'ADN, la survie et la croissance des cellules. Dans notre étude, nous avons utilisé des clones issus de lymphocytes T cytotoxiques surexprimant la télomérase afin d'étudier les mécanismes moléculaires qui règlent leur prolifération et leur sénescence. Nous avons montré que les «jeunes » cellules T exprimant ou non hTERT révèlent des taux de croissance identiques suite à des réponses de stimulation induites par des mitogènes. De plus, aucun changement global dans leur expression des gènes n'a pu être mis en évidence. Curieusement, nous avons observé des réponses réduites dans la prolifération des cellules transduites avec la télomérase qui présentaient une élongation des télomères et une durée de vie prolongée. Ces cellules, malgré le maintien d'un niveau élevé de l'expression de gènes impliqués dans la progression du cycle cellulaire, ont également montré une expression accrue de plusieurs gènes trouvés en commun avec nos lymphocytes T vieillissants n'exprimant pas de télomérase. En particulier, les cellules ayant une durée de vie prolongée grâce à l'expression de la télomérase accumulaient également certains inhibiteurs du cycle cellulaire tels que p16Ink4a et p21Cip1, associés à l'arrêt de la croissance cellulaire. En résumé, nos résultats indiquent la présence fonctionnelle de mécanismes alternatifs pouvant contrôler la croissance réplicative de ces cellules; ils sont donc encourageants dans l'optique d'une utilisation à moindre risque de lymphocytes T «immortalisés » à des fins thérapeutiques pour traiter les tumeurs malignes ou les infections. Summary Most mature blood cells have a finite life span. In human somatic cells, including T lymphocytes, telomeres progressively shorten with each cell division eventually leading to chromosomal instability. Ectopic expression of the human telomerase reverse transcriptase (hTERT) gene in cells restores telomerase activity and results in the extension of their replicative life span. Despite lack of transformation characteristics, it is yet unknown whether somatic cells that over-express telomerase are biologically and physiologically indistinguishable from normal cells. Recent data suggest that telomerase might mediate additional functions in DNA repair, cell survival and cell growth. Using CD8+ T lymphocyte clones over-expressing telomerase we investigated the molecular mechanisms that regulate T cell proliferation and senescence. Here we show that early-passage T cell clones transduced or not with hTERT displayed identical growth rates upon mitogenic stimulation and no marked global changes in gene expression. Surprisingly, reduced proliferative responses were observed in hTERT-transduced cells with elongated telomeres and extended life span. These cells, despite maintaining high expression level of genes involved in cell cycle division and progression, also showed increased expression of several genes associated with normal aging T lymphocytes. In particular, late passage T cells over-expressing telomerase accumulated the cyclin-dependent inhibitors p16INK4a and p21CIP1 that have largely been associated with in vitro growth arrest. Whether tumor-reactive CD8+ T cells that ectopically express telomerase could now be used for adoptive transfer therapy in cancer patients remains unclear at this point. Nevertheless, our results regarding the safe and effective use of hTERT-transduced lymphocytes are encouraging, since they indicate that alternative growth arrest mechanisms such as p 16 and p21 are still functional in these cells and regulate to some extend their growth potential.

Modeling complex wells with the multi-scale finite-volume method

In this paper, an extension of the multi-scale finite-volume (MSFV) method is devised, which allows to Simulate flow and transport in reservoirs with complex well configurations. The new framework fits nicely into the data Structure of the original MSFV method,and has the important property that large patches covering the whole well are not required. For each well. an additional degree of freedom is introduced. While the treatment of pressure-constraint wells is trivial (the well-bore reference pressure is explicitly specified), additional equations have to be solved to obtain the unknown well-bore pressure of rate-constraint wells. Numerical Simulations of test cases with multiple complex wells demonstrate the ability of the new algorithm to capture the interference between the various wells and the reservoir accurately. (c) 2008 Elsevier Inc. All rights reserved.

Amoeba-resisting Chlamydiales present in domestic drinking water and their potential role in pneumonia

Chlamydia-related bacteria classified in the Chlamydiales order, are strictly intracellular bacteria and are able for the most to replicate in free-living amoebae. Amoebae, ubiquitous in the environment and especially in water, are very resistant to disinfection used in drinking water production. Thus, amoebae may reach easily the distribution and domestic water system, potentially sheltering amoeba-resisting bacteria including Legionella, mycobacteria and Chlamydiales. Indeed, some of these amoeba-resisting bacteria have been shown to cause respiratory infections in people inhaling contaminated water. Therefore, an environmental and clinical study was conducted to determine if Chlamydiales bacteria are also involved in respiratory infections and if a transmission through domestic drinking water could occur. First, large scale molecular and serological tools specific of Chlamydia-related bacteria were developed and then were applied on clinical samples from patients with and without pneumonia. Simultaneously, water and biofilm samples from households of the same patients were investigated using molecular and culture methods for the presence of Chlamydiales bacteria. Chlamydiales were detected in the nasopharyngeal flora from patients with and without pneumonia. However, no significant difference was observed between both groups. Conversely, serological investigations showed that antibody reactivity against members of the Criblamydiaceae was associated with pneumonia. The thesis provided very efficient tools that showed the presence of Chlamydiales in human nasopharyngeal flora as well as in the majority of the domestic drinking water. However, no transmission from domestic drinking water to human could be demonstrated. These tools will help in the future specifying the ecology and pathogenicity of the Chlamydia-re\ated bacteria and especially of the species belonging to the Criblamydiaceae family.

Biotic potential and reproductive parameters of Spodoptera eridania (Stoll) (Lepidoptera, Noctuidae) in the laboratory

Biotic potential and reprodutcive parameters of Spodoptera eridania (Stoll) (Lepidoptera, Noctuidae) in the laboratory: This study aimed to evaluate the biotic potential and reproductive parameters of Spodoptera eridania (Stoll, 1782) under controlled conditions (25 ± 1ºC, 70 ± 10% RH and 14 hour photophase). The longevity, pre-, post- and oviposition periods, fecundity and fertility of 15 couples was evaluated. The longevity of females (10.80 days) was not significantly higher than those of males (9.27 days). The mean durations of the pre, post and oviposition periods were 2.067, 0.600 and 8.133 days, respectively. The mean fecundity per female was 1,398 eggs and the mean fertility was 1,367.50 larvae. On average, females copulated 1.133 times. A strong positive correlation was observed between the number of mating and fecundity (r = 0.881, P <0.001). However a strong negative correlation was observed between the number of copulations and the duration of the pre-oviposition period (r = -0.826, P = 0.002) and longevity (r = -0.823, P = 0.001). The biotic potential of S. eridania was estimated at 1.894 x 10(25) individuals/female/year. The net reproductive rate (Ro) was 560.531 times per generation and the mean generation time (T) was 35.807 days. The intrinsic rate of increase (rm) was 0.177, with a finite rate of increase (l) of 1.193, per week

Predicting the potential for lightning activity in mediterranean storms based on the WRF model dynamic and microphysical fields

A new parameter is introduced: the lightning potential index (LPI), which is a measure of the potential for charge generation and separation that leads to lightning flashes in convective thunderstorms. The LPI is calculated within the charge separation region of clouds between 0 C and 20 C, where the noninductive mechanism involving collisions of ice and graupel particles in the presence of supercooled water is most effective. As shown in several case studies using the Weather Research and Forecasting (WRF) model with explicit microphysics, the LPI is highly correlated with observed lightning. It is suggested that the LPI may be a useful parameter for predicting lightning as well as a tool for improving weather forecasting of convective storms and heavy rainfall.