61 research outputs found

    Enhanced functional synchronization of medial and lateral PFC underlies internally-guided action planning

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    Actions are often internally guided, reflecting our covert will and intentions. The dorsomedial prefrontal cortex, including the pre-Supplementary Motor Area (pre-SMA), has been implicated in the internally generated aspects of action planning, such as choice and intention. Yet, the mechanism by which this area interacts with other cognitive brain regions such as the dorsolateral prefrontal cortex, a central node in decision-making, is still unclear. To shed light on this mechanism, brain activity was measured via fMRI and intracranial EEG in two studies during the performance of visually cued repeated finger tapping in which the choice of finger was guided by either a presented number (external) or self-choice (internal). A functional-MRI (fMRI) study in 15 healthy participants demonstrated that the pre-SMA, compared to the SMA proper, was more active and also more functionally correlated with the dorsolateral prefrontal cortex during internally compared to externally guided action planning (p < 0.05, random effect). In a similar manner, an intracranial-EEG study in five epilepsy patients showed greater inter-regional gamma-related connectivity between electrodes situated in medial and lateral aspects of the prefrontal cortex for internally compared to externally guided actions. Although this finding was observed for groups of electrodes situated both in the pre-SMA and SMA-proper, increased intra-cluster gamma-related connectivity was only observed for the pre-SMA (sign-test, p < 0.0001). Overall our findings provide multi-scale indications for the involvement of the dorsomedial prefrontal cortex, and especially the pre-SMA, in generating internally guided motor planning. Our intracranial-EEG results further point to enhanced functional connectivity between decision-making- and motor planning aspects of the PFC, as a possible neural mechanism for internally generated action planning

    Calcium Handling in Human Induced Pluripotent Stem Cell Derived Cardiomyocytes

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    BACKGROUND: The ability to establish human induced pluripotent stem cells (hiPSCs) by reprogramming of adult fibroblasts and to coax their differentiation into cardiomyocytes opens unique opportunities for cardiovascular regenerative and personalized medicine. In the current study, we investigated the Ca(2+)-handling properties of hiPSCs derived-cardiomyocytes (hiPSC-CMs). METHODOLOGY/PRINCIPAL FINDINGS: RT-PCR and immunocytochemistry experiments identified the expression of key Ca(2+)-handling proteins. Detailed laser confocal Ca(2+) imaging demonstrated spontaneous whole-cell [Ca(2+)](i) transients. These transients required Ca(2+) influx via L-type Ca(2+) channels, as demonstrated by their elimination in the absence of extracellular Ca(2+) or by administration of the L-type Ca(2+) channel blocker nifedipine. The presence of a functional ryanodine receptor (RyR)-mediated sarcoplasmic reticulum (SR) Ca(2+) store, contributing to [Ca(2+)](i) transients, was established by application of caffeine (triggering a rapid increase in cytosolic Ca(2+)) and ryanodine (decreasing [Ca(2+)](i)). Similarly, the importance of Ca(2+) reuptake into the SR via the SR Ca(2+) ATPase (SERCA) pump was demonstrated by the inhibiting effect of its blocker (thapsigargin), which led to [Ca(2+)](i) transients elimination. Finally, the presence of an IP3-releasable Ca(2+) pool in hiPSC-CMs and its contribution to whole-cell [Ca(2+)](i) transients was demonstrated by the inhibitory effects induced by the IP3-receptor blocker 2-Aminoethoxydiphenyl borate (2-APB) and the phospholipase C inhibitor U73122. CONCLUSIONS/SIGNIFICANCE: Our study establishes the presence of a functional, SERCA-sequestering, RyR-mediated SR Ca(2+) store in hiPSC-CMs. Furthermore, it demonstrates the dependency of whole-cell [Ca(2+)](i) transients in hiPSC-CMs on both sarcolemmal Ca(2+) entry via L-type Ca(2+) channels and intracellular store Ca(2+) release

    Microbial and Chemical Characterization of Underwater Fresh Water Springs in the Dead Sea

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    Due to its extreme salinity and high Mg concentration the Dead Sea is characterized by a very low density of cells most of which are Archaea. We discovered several underwater fresh to brackish water springs in the Dead Sea harboring dense microbial communities. We provide the first characterization of these communities, discuss their possible origin, hydrochemical environment, energetic resources and the putative biogeochemical pathways they are mediating. Pyrosequencing of the 16S rRNA gene and community fingerprinting methods showed that the spring community originates from the Dead Sea sediments and not from the aquifer. Furthermore, it suggested that there is a dense Archaeal community in the shoreline pore water of the lake. Sequences of bacterial sulfate reducers, nitrifiers iron oxidizers and iron reducers were identified as well. Analysis of white and green biofilms suggested that sulfide oxidation through chemolitotrophy and phototrophy is highly significant. Hyperspectral analysis showed a tight association between abundant green sulfur bacteria and cyanobacteria in the green biofilms. Together, our findings show that the Dead Sea floor harbors diverse microbial communities, part of which is not known from other hypersaline environments. Analysis of the water’s chemistry shows evidence of microbial activity along the path and suggests that the springs supply nitrogen, phosphorus and organic matter to the microbial communities in the Dead Sea. The underwater springs are a newly recognized water source for the Dead Sea. Their input of microorganisms and nutrients needs to be considered in the assessment of possible impact of dilution events of the lake surface waters, such as those that will occur in the future due to the intended establishment of the Red Sea−Dead Sea water conduit

    Privatisation, outsourcing and employment relations in Israel

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    This chapter focuses on the effect that outsourcing, as a subset of privatization, has had on employment relations in Israel. In particular, chapter highlights the adverse, and perhaps counter-intuitive, effects that the law has had on the plight of Israeli contract workers. Israeli governmental agencies and local councils have turned to outsourcing as a means to circumventing post limits and due to the Ministry of Finance’s pressures to increase ‘flexibility’ in the civil service. Intriguingly, paradoxically, and tragically, the law’s effort to regulate this growing phenomenon has led employers resorting to tactics which have redefined agency workers (teachers, nurses, etc) as workers subject to the “outsourcing of services” (teaching, nursing, etc). This has moved such workers into a legal void, depriving them of rights and protection

    Coaxial stereo and scale-based matching

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    The past decade has seen a growing interest in computer stereo vision: the recovery of the depth map of a scene from two-dimensional images. The main problem of computer stereo is in establishing correspondence between features or regions in two or more images. This is referred to as the correspondence problem. One way to reduce the difficulty of the above problem is to constrain the camera modeling. Conventional stereo systems use two or more cameras, which are positioned in space at a uniform distance from the scene. These systems use epipolar geometry for their camera modeling, in order to curb the search space to be one-dimensional - along epipolar lines. Following Jain's approach, this thesis exploits a non-conventional camera modeling: the cameras are positioned in space one behind the other, such that their optical axes are collinear (hence the name coaxial stereo), and their distance apart is known. This approach complies with a simple case of epipolar geometry which further reduces the magnitude of the correspondence problem. The displacement of the projection of a stationary point occurs along a radial line, and depends only on its spatial depth and the distance between the cameras. Thus, to simplify (significantly) the recovery of depth from disparity, complex logarithmic mapping is applied to the original images. The logarithmic part of the transformation introduces great distortion to the image's resolution. Therefore, to minimize this distortion, it is applied to the features used in the matching process. The search for matching features is conducted along radial lines. Following Mokhtarian and Mackworth's approach, a scale-space image is constructed for each radial line by smoothing its intensity profile with a Gaussian filter, and finding zero-crossings in the second derivative at varying scale levels. Scale-space images of corresponding radial lines are then matched, based on a modified uniform cost algorithm. The matching algorithm is written with generality in mind. As a consequence, it can be easily adopted to other stereoscopic systems. Some new results on the structure of scale-space images of one dimensional functions are presented.Science, Faculty ofComputer Science, Department ofGraduat

    Almost Midnight

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    200 hal.; ill.; 22c
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