14,547 research outputs found

    Corticostriatal Transmission Is Selectively Enhanced in Striatonigral Neurons with Postnatal Loss of Tsc1.

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    mTORC1 is a central signaling hub that integrates intra- and extracellular signals to regulate a variety of cellular metabolic processes. Mutations in regulators of mTORC1 lead to neurodevelopmental disorders associated with autism, which is characterized by repetitive, inflexible behaviors. These behaviors may result from alterations in striatal circuits that control motor learning and habit formation. However, the consequences of mTORC1 dysregulation on striatal neuron function are largely unknown. To investigate this, we deleted the mTORC1 negative regulator Tsc1 from identified striatonigral and striatopallidal neurons and examined how cell-autonomous upregulation of mTORC1 activity affects their morphology and physiology. We find that loss of Tsc1 increases the excitability of striatonigral, but not striatopallidal, neurons and selectively enhances corticostriatal synaptic transmission. These findings highlight the critical role of mTORC1 in regulating striatal activity in a cell type- and input-specific manner, with implications for striatonigral pathway dysfunction in neuropsychiatric disease

    Integrin α2β1 Expression Regulates Matrix Metalloproteinase-1-Dependent Bronchial Epithelial Repair in Pulmonary Tuberculosis.

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    Pulmonary tuberculosis (TB) is caused by inhalation of Mycobacterium tuberculosis, which damages the bronchial epithelial barrier to establish local infection. Matrix metalloproteinase-1 plays a crucial role in the immunopathology of TB, causing breakdown of type I collagen and cavitation, but this collagenase is also potentially involved in bronchial epithelial repair. We hypothesized that the extracellular matrix (ECM) modulates M. tuberculosis-driven matrix metalloproteinase-1 expression by human bronchial epithelial cells (HBECs), regulating respiratory epithelial cell migration and repair. Medium from monocytes stimulated with M. tuberculosis induced collagenase activity in bronchial epithelial cells, which was reduced by ~87% when cells were cultured on a type I collagen matrix. Matrix metalloproteinase-1 had a focal localization, which is consistent with cell migration, and overall secretion decreased by 32% on type I collagen. There were no associated changes in the specific tissue inhibitors of metalloproteinases. Decreased matrix metalloproteinase-1 secretion was due to ligand-binding to the α2β1 integrin and was dependent on the actin cytoskeleton. In lung biopsies, samples from patients with pulmonary TB, integrin α2β1 is highly expressed on the bronchial epithelium. Areas of lung with disrupted collagen matrix showed an increase in matrix metalloproteinases-1 expression compared with areas where collagen was comparable to control lung. Type I collagen matrix increased respiratory epithelial cell migration in a wound-healing assay, and this too was matrix metalloproteinase-dependent, since it was blocked by the matrix metalloproteinase inhibitor GM6001. In summary, we report a novel mechanism by which α2β1-mediated signals from the ECM modulate matrix metalloproteinase-1 secretion by HBECs, regulating their migration and epithelial repair in TB

    Kinetic Equation for a Plasma and Its Application to High-frequency Conductivity

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    Kinetic equation for inhomogenious nonisotropic plasma and application to high frequency conductivit

    Empires and Percolation: Stochastic Merging of Adjacent Regions

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    We introduce a stochastic model in which adjacent planar regions A,BA, B merge stochastically at some rate λ(A,B)\lambda(A,B), and observe analogies with the well-studied topics of mean-field coagulation and of bond percolation. Do infinite regions appear in finite time? We give a simple condition on λ\lambda for this {\em hegemony} property to hold, and another simple condition for it to not hold, but there is a large gap between these conditions, which includes the case λ(A,B)1\lambda(A,B) \equiv 1. For this case, a non-rigorous analytic argument and simulations suggest hegemony.Comment: 13 page

    Assembly Guidance in Augmented Reality Environments Using a Virtual Interactive Tool

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    The application of augmented reality (AR) technology for assembly guidance is a novel approach in the traditional manufacturing domain. In this paper, we propose an AR approach for assembly guidance using a virtual interactive tool that is intuitive and easy to use. The virtual interactive tool, termed the Virtual Interaction Panel (VirIP), involves two tasks: the design of the VirIPs and the real-time tracking of an interaction pen using a Restricted Coulomb Energy (RCE) neural network. The VirIP includes virtual buttons, which have meaningful assembly information that can be activated by an interaction pen during the assembly process. A visual assembly tree structure (VATS) is used for information management and assembly instructions retrieval in this AR environment. VATS is a hierarchical tree structure that can be easily maintained via a visual interface. This paper describes a typical scenario for assembly guidance using VirIP and VATS. The main characteristic of the proposed AR system is the intuitive way in which an assembly operator can easily step through a pre-defined assembly plan/sequence without the need of any sensor schemes or markers attached on the assembly components.Singapore-MIT Alliance (SMA

    Optical investigation of the charge-density-wave phase transitions in NbSe3NbSe_{3}

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    We have measured the optical reflectivity R(ω)R(\omega) of the quasi one-dimensional conductor NbSe3NbSe_{3} from the far infrared up to the ultraviolet between 10 and 300 KK using light polarized along and normal to the chain axis. We find a depletion of the optical conductivity with decreasing temperature for both polarizations in the mid to far-infrared region. This leads to a redistribution of spectral weight from low to high energies due to partial gapping of the Fermi surface below the charge-density-wave transitions at 145 K and 59 K. We deduce the bulk magnitudes of the CDW gaps and discuss the scattering of ungapped free charge carriers and the role of fluctuations effects

    Linking the exotic structure of 17{}^{17}C to its unbound mirror 17{}^{17}Na

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    The structure of 17{}^{17}C is used to define a nuclear interaction that, when used in a multichannel algebraic scattering theory for the n+16n+{}^{16}C system, gives a credible definition of the (compound) excitation spectra. When couplings to the low-lying collective excitations of the 16{}^{16}C-core are taken into account, both sub-threshold and resonant states about the n+16n+{}^{16}C threshold are found. Adding Coulomb potentials to that nuclear interaction, the method is used for the mirror system of p+16p+{}^{16}Ne to specify the low-excitation spectrum of the particle unstable 17^{17}Na. We compare the results with those of a microscopic cluster model. A spectrum of low excitation resonant states in 17{}^{17}Na is found with some differences to that given by the microscopic-cluster model. The calculated resonance half-widths (for proton emission) range from 2\sim 2 to 672\sim 672 keV.Comment: 13 pages, 5 figure
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