Low-temperature ion beam mixing of Pt and Si markers in Ge

The mixing of Pt and Si marker atoms in Ge during 750-keV Xe irradiation was measured at temperatures between 6 and 500 K. The low-temperature measurements show that the mixing parameter for Pt is nearly twice that for Si. This result is in strong contradiction to the collisional theory of ion beam mixing. A weak temperature dependence in the mixing is found for both markers

Predicting wind turbine blade loads using vorticity transport and RANS methodologies

Two computational methods, one based on the solution of the vorticity transport equation, and a second based on the solution of the Reynolds-Averaged Navier-Stokes equations, have been used to simulate the aerodynamic performance of a horizontal axis wind turbine. Comparisons have been made against data obtained during Phase VI of the NREL Unsteady Aerodynamics Experimental and against existing numerical data for a range of wind conditions. The Reynolds-Averaged Navier-Stokes method demonstrates the potential to predict accurately the flow around the blades and the distribution of aerodynamic loads developed on them. The Vorticity Transport Model possesses a considerable advantage in those situtations where the accurate, but computationally efficient, modelling of the structure of the wake and the associated induced velocity is critical, but where the prediction of blade loads can be achieved with sufficient accuracy using a lifting-line model augmented by incorporating a semi-empirical stall delay model. The largest benefits can be extracted when the two methods are used to complement each other in order to understand better the physical mechanisms governing the aerodynamic performance of wind turbines

Tree indiscernibilities, revisited

We give definitions that distinguish between two notions of indiscernibility for a set \{a_\eta \mid \eta \in \W\} that saw original use in \cite{sh90}, which we name \textit{\s-} and \textit{\n-indiscernibility}. Using these definitions and detailed proofs, we prove \s- and \n-modeling theorems and give applications of these theorems. In particular, we verify a step in the argument that TP is equivalent to TP$_1$ or TP$_2$ that has not seen explication in the literature. In the Appendix, we exposit the proofs of \citep[{App. 2.6, 2.7}]{sh90}, expanding on the details.Comment: submitte

Attosecond counter-rotating-wave effect in xenon driven by strong fields

We investigate the subfemtosecond dynamics of a highly excited xenon atom coherently driven by a strong control field at which the Rabi frequency of the system is comparable to the frequency of a driving laser. The widely used rotating-wave approximation breaks down at such fields, resulting in features such as the counter-rotating-wave (CRW) effect. We present a time-resolved observation of the CRW effect in the highly excited 4d-1np xenon using attosecond transient absorption spectroscopy. Time-dependent many-body theory confirms the observation and explains the various features of the absorption spectrum seen in experiment. ?2017 American Physical Society.111Ysciescopu

Quantum linear amplifier enhanced by photon subtraction and addition

A deterministic quantum amplifier inevitably adds noise to an amplified signal due to the uncertainty principle in quantum physics. We here investigate how a quantum-noise-limited amplifier can be improved by additionally employing the photon subtraction, the photon addition, and a coherent superposition of the two, thereby making a probabilistic, heralded, quantum amplifier. We show that these operations can enhance the performance in amplifying a coherent state in terms of intensity gain, fidelity, and phase uncertainty. In particular, the photon subtraction turns out to be optimal for the fidelity and the phase concentration among these elementary operations, while the photon addition also provides a significant reduction in the phase uncertainty with the largest gain effect.Comment: published version, 7 pages, 9 figure

Femtochemistry of mass-selected negative-ion clusters of dioxygen: Charge-transfer and solvation dynamics

Femtosecond, time-resolved photoelectron spectroscopy is used to investigate the dissociation dynamics of mass-selected anionic molecular-oxygen clusters. The observed transient photoelectron signal for the clusters (O_2)^−_n  (n = 3–5) shows the O^−_2 production; for n = 1 and 2, we observe no time-dependence at this wavelength of 800 nm. The observed transients are bi-exponential in form with two distinct time constants, but with clear trends, for all investigated cluster sizes. These striking observations describe the reaction pathways of the solvated core and we elucidate two primary processes: Charge transfer with concomitant nuclear motion, and direct dissociation of the O^−_4 core-ion via electron recombination; the former takes 700–2700 fs, while the latter is on a shorter time scale, 110–420 fs. Both rates decrease differently upon increasing cluster size, indicating the critical role of step-wise solvation

Exosomes from Human Adipose Tissue-Derived Mesenchymal Stem Cells Promote Epidermal Barrier Repair by Inducing de Novo Synthesis of Ceramides in Atopic Dermatitis.

Atopic dermatitis (AD) is a multifactorial, heterogeneous disease associated with epidermal barrier disruption and intense systemic inflammation. Previously, we showed that exosomes derived from human adipose tissue-derived mesenchymal stem cells (ASC-exosomes) attenuate AD-like symptoms by reducing multiple inflammatory cytokine levels. Here, we investigated ASC-exosomes' effects on skin barrier restoration by analyzing protein and lipid contents. We found that subcutaneous injection of ASC-exosomes in an oxazolone-induced dermatitis model remarkably reduced trans-epidermal water loss, while enhancing stratum corneum (SC) hydration and markedly decreasing the levels of inflammatory cytokines such as IL-4, IL-5, IL-13, TNF-α, IFN-γ, IL-17, and TSLP, all in a dose-dependent manner. Interestingly, ASC-exosomes induced the production of ceramides and dihydroceramides. Electron microscopic analysis revealed enhanced epidermal lamellar bodies and formation of lamellar layer at the interface of the SC and stratum granulosum with ASC-exosomes treatment. Deep RNA sequencing analysis of skin lesions demonstrated that ASC-exosomes restores the expression of genes involved in skin barrier, lipid metabolism, cell cycle, and inflammatory response in the diseased area. Collectively, our results suggest that ASC-exosomes effectively restore epidermal barrier functions in AD by facilitating the de novo synthesis of ceramides, resulting in a promising cell-free therapeutic option for treating AD

The Lunar Neon Exosphere Seen in LACE Data

Using the LACE data from Apollo 17 we have found measured neon densities consistent with the 20Ne surface number densities reported by Cook et al. (2013) for normal conditions, terminator surface densities of 3 (1.5) 10(exp 3) per cu.cm. These values are almost an order of magnitude less than those reported by Benna et al. (2015) for CME conditions. Using a Monte Carlo model and assuming the normal solar wind and a photoionization lifetime for Ne of 300 days, our result was more consistent with the Benna (2015) result than our measured result. Two lunations showed an increase in Ne during the night, consistent with the simulation, but two of the lunations showed a decrease in surface number density through the night. We have shown that explaining the Ne distribution is not as simple as assuming dynamic equilibrium with the solar wind and an exosphere accommodated to the local surface temperature

Prediction of unsteady blade loads of a wind turbine using RANS and vorticity transport methodologies

Numerical simulations of the NREL phase VI wind turbine operating in yawed conditions have been performed using two computational methods; one based on the solution of the Reynolds-averaged Navier-Stokes equations (RANS) using unstructured overset meshes and one known as the Vorticity Transport Model (VTM) that is based on the solution of the vorticity transport equation. The effect of the hub that was present during the NREL experiments was investigated by modeling the hub in the RANS simulations. It was found that the hub influenced the loading significantly at the inboard part of the blade when the blade passed through the wake that was developed by the hub. Both the RANS and VTM codes are able to predict well the unsteady and time-averaged aerodynamic loadings on the wind turbine blades at low wind speeds. At high wind speeds, leading-edge flow separation and strong radial flow are observed on the suction surface of the blades, when the blades are at the retreating side of the rotor. Both the RANS and VTM codes provide less accurate predictions of the blade loads. However, at the advancing side of the rotor, the flow is mostly attached to the surface of the blade, and both the RANS and VTM predictions of the blade loads are in good agreement with the measured data