Subtype-specific plasticity of inhibitory circuits in motor cortex during motor learning.

Motor skill learning induces long-lasting reorganization of dendritic spines, principal sites of excitatory synapses, in the motor cortex. However, mechanisms that regulate these excitatory synaptic changes remain poorly understood. Here, using in vivo two-photon imaging in awake mice, we found that learning-induced spine reorganization of layer (L) 2/3 excitatory neurons occurs in the distal branches of their apical dendrites in L1 but not in the perisomatic dendrites. This compartment-specific spine reorganization coincided with subtype-specific plasticity of local inhibitory circuits. Somatostatin-expressing inhibitory neurons (SOM-INs), which mainly inhibit distal dendrites of excitatory neurons, showed a decrease in axonal boutons immediately after the training began, whereas parvalbumin-expressing inhibitory neurons (PV-INs), which mainly inhibit perisomatic regions of excitatory neurons, exhibited a gradual increase in axonal boutons during training. Optogenetic enhancement and suppression of SOM-IN activity during training destabilized and hyperstabilized spines, respectively, and both manipulations impaired the learning of stereotyped movements. Our results identify SOM inhibition of distal dendrites as a key regulator of learning-related changes in excitatory synapses and the acquisition of motor skills

Precision of single-qubit gates based on Raman transitions

We analyze the achievable precision for single-qubit gates that are based on Raman transitions between two near-degenerate ground states via a virtually excited state. In particular, we study the errors due to non-perfect adiabaticity and due to spontaneous emission from the excited state. For the case of non-adabaticity, we calculate the error as a function of the dimensionless parameter $\chi=\Delta \tau$, where $\Delta$ is the detuning of the Raman beams and $\tau$ is the gate time. For the case of spontaneous emission, we give an analytical argument that the gate errors are approximately equal to $\Lambda \gamma/\Delta$, where $\Lambda$ is the rotation angle of the one-qubit gate and $\gamma$ is the spontaneous decay rate, and we show numerically that this estimate holds to good approximation.Comment: 8 pages, 10 figure

On a Cahn--Hilliard--Darcy system for tumour growth with solution dependent source terms

We study the existence of weak solutions to a mixture model for tumour growth that consists of a Cahn--Hilliard--Darcy system coupled with an elliptic reaction-diffusion equation. The Darcy law gives rise to an elliptic equation for the pressure that is coupled to the convective Cahn--Hilliard equation through convective and source terms. Both Dirichlet and Robin boundary conditions are considered for the pressure variable, which allows for the source terms to be dependent on the solution variables.Comment: 18 pages, changed proof from fixed point argument to Galerkin approximatio

RGS9-1 is required for normal inactivation of mouse cone phototransduction

Purpose: To test the hypothesis that Regulator of G-protein Signaling 9 (RGS9-1) is necessary for the normal inactivation of retinal cones. Methods: Mice having the gene RGS9-1 inactivated in both alleles (RGS9-1 -/-) were tested between the ages 8-10 weeks with electroretinographic (ERG) protocols that isolate cone-driven responses. Immunohistochemistry was performed with a primary antibody against RGS9-1 (anti-RGS9-1c), with the secondary conjugated to fluorescein isothiocyanate, and with rhodamine-conjugated peanut agglutinin. Results: (1) Immunohistochemistry showed RGS9-1 to be strongly expressed in the cones of wildtype (WT is C57BL/6) mice, but absent from the cones of RGS9-1 mice. (2) Cone-driven b-wave responses of dark-adapted RGS9-1 -/- mice had saturating amplitudes and sensitivities in the midwave and UV regions of the spectrum equal to or slightly greater than those of WT (C57BL/6) mice. (3) Cone-driven b-wave and a-wave responses of RGS9-1 -/- mice recovered much more slowly than those of WT after a strong conditioning flash: for a flash estimated to isomerize 1.2% of the M-cone pigment and 0.9% of the UV-cone pigment, recovery of 50% saturating amplitude was approximately 60-fold slower than in WT. Conclusions: (1) The amplitudes and sensitivities of the cone-driven responses indicate that cones and cone-driven neurons in RGS9-1 -/- mice have normal generator currents. (2) The greatly retarded recovery of cone-driven responses of RGS9-1 -/- mice relative to those of WT mice establishes that RGS9-1 is required for normal inactivation of the cone phototransduction cascades of both UV- and M-cones

RhoA/Rho kinase (ROCK) alters fetuin-A uptake and regulates calcification in bovine vascular smooth muscle cells (BVSMC)

RhoA/Rho kinases (ROCK) play a critical role in vascular smooth muscle cell (VSMC) actin cytoskeleton organization, differentiation, and function and are implicated in the pathogenesis of cardiovascular disease. We have previously determined that an important step in the regulation of calcification is fetuin-A endocytosis, a process that is dependent on changes in the cytoskeleton, which, in turn, is known to be affected by the RhoA/ROCK signaling pathway. In the present study, bovine VSMC (BVSMC) were treated with the ROCK inhibitor Y-27632 or transfected with ROCK small interfering (si) RNA to knock down ROCK expression. Both conditions resulted in reduced actin stress fibers and increased Cy5-labeled fetuin-A uptake. Inhibition of ROCK by Y-27632 or siRNA also significantly increased BVSMC alkaline phosphatase (ALP) activity and calcification of BVSMC and rat aorta organ cultures. Cells were then incubated in calcification media in the presence or absence of Y-27632 and matrix vesicles (MV) isolated by collagenase digestion. These MV, isolated from BVSMC incubated with Y-27632, had increased ALP activity and increased ability of MV to subsequently calcify collagen by 66%. In contrast, activation of RhoA, which is upstream of ROCK, by transfecting plasmids encoding the dominant active Rho GTPase mutant (Rho-L63) led to decreased fetuin-A uptake and reduced calcification in BVSMC. These results demonstrate that the RhoA/ROCK signaling pathway is an important negative regulator of vascular calcification

Theoretical predictions for vehicular headways and their clusters

This article presents a derivation of analytical predictions for steady-state distributions of netto time gaps among clusters of vehicles moving inside a traffic stream. Using the thermodynamic socio-physical traffic model with short-ranged repulsion between particles (originally introduced in [Physica A \textbf{333} (2004) 370]) we firstly derive the time-clearance distribution in the model. Consecutively, the statistical distributions for the so-called time multi-clearances are calculated by means of theory of functional convolutions. Moreover, all the theoretical surmises used during the above-mentioned calculations are proven by the statistical analysis of traffic data. The mathematical predictions acquired in this paper are thoroughly compared with relevant empirical quantities and discussed in the context of three-phase traffic theory.Comment: 23 pages, 10 figure

Is SN 2006X from a WD + MS system with optically thick wind?

The single-degenerate channel is widely accepted as the progenitors of type Ia supernovae (SNe Ia). Following the work of Meng, Chen and Han (2009), we reproduced the birth rate and age of supernovae like SN 2006X by the single-degenerate model (WD + MS) with an optically thick wind, which may imply that the progenitor of SN 2006X is a WD + MS system.Comment: 10 pages, 2 figures, accepted for publication in New

Using Markov Models and Statistics to Learn, Extract, Fuse, and Detect Patterns in Raw Data

Many systems are partially stochastic in nature. We have derived data driven approaches for extracting stochastic state machines (Markov models) directly from observed data. This chapter provides an overview of our approach with numerous practical applications. We have used this approach for inferring shipping patterns, exploiting computer system side-channel information, and detecting botnet activities. For contrast, we include a related data-driven statistical inferencing approach that detects and localizes radiation sources.Comment: Accepted by 2017 International Symposium on Sensor Networks, Systems and Securit

Experimental Quantum Cryptography with Qutrits

We produce two identical keys using, for the first time, entangled trinary quantum systems (qutrits) for quantum key distribution. The advantage of qutrits over the normally used binary quantum systems is an increased coding density and a higher security margin. The qutrits are encoded into the orbital angular momentum of photons, namely Laguerre-Gaussian modes with azimuthal index l +1, 0 and -1, respectively. The orbital angular momentum is controlled with phase holograms. In an Ekert-type protocol the violation of a three-dimensional Bell inequality verifies the security of the generated keys. A key is obtained with a qutrit error rate of approximately 10 %.Comment: New version includes additional references and a few minor changes to the manuscrip

Rotating molecular outflows: the young T Tauri star in CB26

The disk-outflow connection is thought to play a key role in extracting excess angular momentum from a forming proto-star. Though jet rotation has been observed in a few objects, no rotation of molecular outflows has been unambiguously reported so far. We report new millimeter-interferometric observations of the edge-on T Tauri star - disk system in the isolated Bok globule CB26. The aim of these observations was to study the disk-outflow relation in this 1Myr old low-mass young stellar object. The IRAM PdBI array was used to observe 12CO(2-1) at 1.3mm in two configurations, resulting in spectral line maps with 1.5 arcsec resolution. We use an empirical parameterized steady-state outflow model combined with 2-D line radiative transfer calculations and chi^2-minimization in parameter space to derive a best-fit model and constrain parameters of the outflow. The data reveal a previously undiscovered collimated bipolar molecular outflow of total length ~2000 AU, escaping perpendicular to the plane of the disk. We find peculiar kinematic signatures that suggest the outflow is rotating with the same orientation as the disk. However, we could not ultimately exclude jet precession or two misaligned flows as possible origin of the observed peculiar velocity field. There is indirect indication that the embedded driving source is a binary system, which, together with the youth of the source, could provide the clue to the observed kinematic features of the outflow. CB26 is so far the most promising source to study the rotation of a molecular outflow. Assuming that the outflow is rotating, we compute and compare masses, mass flux, angular momenta, and angular momentum flux of disk and outflow and derive disk dispersal timescales of 0.5...1 Myr, comparable to the age of the system.Comment: 14 pages, 6 figures, to appear in Astronomy & Astrophysic