2,153 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
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
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
Quantum computations with atoms in optical lattices: marker qubits and molecular interactions
We develop a scheme for quantum computation with neutral atoms, based on the
concept of "marker" atoms, i.e., auxiliary atoms that can be efficiently
transported in state-independent periodic external traps to operate quantum
gates between physically distant qubits. This allows for relaxing a number of
experimental constraints for quantum computation with neutral atoms in
microscopic potential, including single-atom laser addressability. We discuss
the advantages of this approach in a concrete physical scenario involving
molecular interactions.Comment: 15 pages, 14 figure
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Prediction of RBNS and IBNR claims using claim amounts and claim counts
A model is proposed using the run-off triangle of paid claims and also the numbers of reported claims (in a similar triangular array). These data are usually available, and allow the model proposed to be implemented in a large variety of situations. On the basis of these data, the stochastic model is built from detailed assumptions for individual claims, but then approximated using a compound Poisson framework. The model explicitly takes into account the delay from when a claim is incurred and to when it is reported (the IBNR delay)and the delay from when a claim is reported and to when it is fully paid (the RBNS delay). These two separate sources of delay are estimated separately, unlike most other reserving methods. The results are compared with those of the chain ladder technique
Tailoring of motional states in double-well potentials by time-dependent processes
We show that the vibrational state tailoring method developed for molecular
systems can be applied for cold atoms in optical lattices. The original method
is based on a three-level model interacting with two strong laser pulses in a
counterintuitive sequence [M. Rodriguez et al., Phys. Rev. A 62, 053413
(2000)]. Here we outline the conditions for achieving similar dynamics with
single time-dependent potential surfaces. It is shown that guided switching
between diabatic and adiabatic evolution has an essential role in this system.
We also show that efficient and precise tailoring of motional states in optical
lattices can be achieved, for instance, simply by superimposing two lattices
and moving them with respect to each other.Comment: 9 pages, 11 figures, 25 references; accepted to PRA; v2: minor
explanatory remarks added & typos correcte
Oscillations in the Sun with SONG: Setting the scale for asteroseismic investigations
Context. We present the first high-cadence multi-wavelength radial-velocity
observations of the Sun-as-a-star, carried out during 57 consecutive days using
the stellar \'echelle spectrograph at the Hertzsprung SONG Telescope operating
at the Teide Observatory. Aims. The aim was to produce a high-quality data set
and reference values for the global helioseismic parameters {\nu_{max}}, and
{\Delta \nu} of the solar p-modes using the SONG instrument. The obtained data
set or the inferred values should then be used when the scaling relations are
applied to other stars showing solar-like oscillations which are observed with
SONG or similar instruments. Methods. We used different approaches to analyse
the power spectrum of the time series to determine {\nu_{max}}; simple Gaussian
fitting and heavy smoothing of the power spectrum. {\Delta\nu} was determined
using the method of autocorrelation of the power spectrum. The amplitude per
radial mode was determined using the method described in Kjeldsen et al.
(2008). Results. We found the following values for the solar oscillations using
the SONG spectrograph: {\nu_{max}} = 3141 {\pm} 12 {\mu}Hz, {\Delta\nu} =
134.98 {\pm} 0.04 {\mu}Hz and an average amplitude of the strongest radial
modes of 16.6 {\pm} 0.4 cm/s. These values are consistent with previous
measurements with other techniques.Comment: 5 pages, 5 figures, letter accepted for A&
One- and two-dimensional quantum walks in arrays of optical traps
We propose a novel implementation of discrete time quantum walks for a
neutral atom in an array of optical microtraps or an optical lattice. We
analyze a one-dimensional walk in position space, with the coin, the additional
qubit degree of freedom that controls the displacement of the quantum walker,
implemented as a spatially delocalized qubit, i.e., the coin is also encoded in
position space. We analyze the dependence of the quantum walk on temperature
and experimental imperfections as shaking in the trap positions. Finally,
combining a spatially delocalized qubit and a hyperfine qubit, we also give a
scheme to realize a quantum walk on a two-dimensional square lattice with the
possibility of implementing different coin operators.Comment: 10 pages, 8 figures; v2: some comments added and other minor change
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