1,815 research outputs found
TGF beta type II receptor signaling controls Schwann cell death and proliferation in developing nerves
During development, Schwann cell numbers are precisely adjusted to match the number of axons. It is essentially unknown which growth factors or receptors carry out this important control in vivo. Here, we tested whether the type II transforming growth factor (TGF)beta receptor has a role in this process. We generated a conditional knock-out mouse in which the type II TGF beta receptor is specifically ablated only in Schwann cells. Inactivation of the receptor, evident at least from embryonic day 18, resulted in suppressed Schwann cell death in normally developing and injured nerves. Notably, the mutants also showed a strong reduction in Schwann cell proliferation. Consequently, Schwann cell numbers in wild-type and mutant nerves remained similar. Lack of TGF beta signaling did not appear to affect other processes in which TGF beta had been implicated previously, including myelination and response of adult nerves to injury. This is the first in vivo evidence for a growth factor receptor involved in promoting Schwann cell division during development and the first genetic evidence for a receptor that controls normal developmental Schwann cell death
Observations of the magnetic field and plasma flow in Jupiter's magnetosheath
Large scale (many minutes to 10 hours) magnetic field structures consisting predominantly of nearly north-south field direction were discovered in Jupiter's magnetosheath from the data of Voyagers 1 and 2 and Pioneer 10 during their outbound encounter trajectories. The Voyager 2 data, and that of Voyager 1 to a lesser extent, show evidence of a quasi-period of 10 hours (and occasionally 5 hours) for these structures. The north-south components of the field and plasma velocity were strongly correlated in the outbound magnetosheath as observed by Voyagers 1 and 2, and the components orthogonal to the north-south direction showed weak correlations. For both Voyager encounters the sense (positive and negative) of the north-south correlations were directly related to the direction of the ecliptic plane component of the interplanetary magnetic field using the field and plasma measurements of the non-encountering spacecraft
Bringing Salary Transparency to the World: Computing Robust Compensation Insights via LinkedIn Salary
The recently launched LinkedIn Salary product has been designed with the goal
of providing compensation insights to the world's professionals and thereby
helping them optimize their earning potential. We describe the overall design
and architecture of the statistical modeling system underlying this product. We
focus on the unique data mining challenges while designing and implementing the
system, and describe the modeling components such as Bayesian hierarchical
smoothing that help to compute and present robust compensation insights to
users. We report on extensive evaluation with nearly one year of de-identified
compensation data collected from over one million LinkedIn users, thereby
demonstrating the efficacy of the statistical models. We also highlight the
lessons learned through the deployment of our system at LinkedIn.Comment: Conference information: ACM International Conference on Information
and Knowledge Management (CIKM 2017
Manipulation of the dynamics of many-body systems via quantum control methods
We investigate how dynamical decoupling methods may be used to manipulate the
time evolution of quantum many-body systems. These methods consist of sequences
of external control operations designed to induce a desired dynamics. The
systems considered for the analysis are one-dimensional spin-1/2 models, which,
according to the parameters of the Hamiltonian, may be in the integrable or
non-integrable limits, and in the gapped or gapless phases. We show that an
appropriate control sequence may lead a chaotic chain to evolve as an
integrable chain and a system in the gapless phase to behave as a system in the
gapped phase. A key ingredient for the control schemes developed here is the
possibility to use, in the same sequence, different time intervals between
control operations.Comment: 10 pages, 3 figure
Detection of solar-like oscillations in relics of the Milky Way: asteroseismology of K giants in M4 using data from the NASA K2 mission
Asteroseismic constraints on K giants make it possible to infer radii, masses
and ages of tens of thousands of field stars. Tests against independent
estimates of these properties are however scarce, especially in the metal-poor
regime. Here, we report the detection of solar-like oscillations in 8 stars
belonging to the red-giant branch and red-horizontal branch of the globular
cluster M4. The detections were made in photometric observations from the K2
Mission during its Campaign 2. Making use of independent constraints on the
distance, we estimate masses of the 8 stars by utilising different combinations
of seismic and non-seismic inputs. When introducing a correction to the Delta
nu scaling relation as suggested by stellar models, for RGB stars we find
excellent agreement with the expected masses from isochrone fitting, and with a
distance modulus derived using independent methods. The offset with respect to
independent masses is lower, or comparable with, the uncertainties on the
average RGB mass (4-10%, depending on the combination of constraints used). Our
results lend confidence to asteroseismic masses in the metal poor regime. We
note that a larger sample will be needed to allow more stringent tests to be
made of systematic uncertainties in all the observables (both seismic and
non-seismic), and to explore the properties of RHB stars, and of different
populations in the cluster.Comment: 6 pages, 3 figures, accepted for publication in MNRA
c-Jun reprograms Schwann cells of injured nerves to generate a repair cell essential for regeneration.
The radical response of peripheral nerves to injury (Wallerian degeneration) is the cornerstone of nerve repair. We show that activation of the transcription factor c-Jun in Schwann cells is a global regulator of Wallerian degeneration. c-Jun governs major aspects of the injury response, determines the expression of trophic factors, adhesion molecules, the formation of regeneration tracks and myelin clearance and controls the distinctive regenerative potential of peripheral nerves. A key function of c-Jun is the activation of a repair program in Schwann cells and the creation of a cell specialized to support regeneration. We show that absence of c-Jun results in the formation of a dysfunctional repair cell, striking failure of functional recovery, and neuronal death. We conclude that a single glial transcription factor is essential for restoration of damaged nerves, acting to control the transdifferentiation of myelin and Remak Schwann cells to dedicated repair cells in damaged tissue
Demonstration of a controllable three-dimensional Brownian motor in symmetric potentials
We demonstrate a Brownian motor, based on cold atoms in optical lattices,
where isotropic random fluctuations are rectified in order to induce controlled
atomic motion in arbitrary directions. In contrast to earlier demonstrations of
ratchet effects, our Brownian motor operates in potentials that are spatially
and temporally symmetric, but where spatiotemporal symmetry is broken by a
phase shift between the potentials and asymmetric transfer rates between them.
The Brownian motor is demonstrated in three dimensions and the noise-induced
drift is controllable in our system.Comment: 5 pages, 4 figure
Brillouin propagation modes in optical lattices: Interpretation in terms of nonconventional stochastic resonance
We report the first direct observation of Brillouin-like propagation modes in a dissipative periodic optical lattice. This has been done by observing a resonant behavior of the spatial diffusion coefficient in the direction corresponding to the propagation mode with the phase velocity of the moving intensity modulation used to excite these propagation modes. Furthermore, we show theoretically that the amplitude of the Brillouin mode is a nonmonotonic function of the strength of the noise corresponding to the optical pumping, and discuss this behavior in terms of nonconventional stochastic resonance
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