bluuebunny/crossref_metadata_2025 huggingface dataset:
Perioperative Vasopressor Use in Free Flap Surgery: A Systematic Review and Meta-Analysis
Authors: Goh Cindy S.L. , Ng Marcus J.M. , Song David H. , Ooi Adrian S.H.
Published: May 2019

Background The use of vasopressors in free flap surgery has traditionally been avoided due to the presumed risk of pedicle vasospasm leading to flap failure. However, there is a lack of strong clinical evidence to suggest that their administration during microvascular surgery is absolutely contraindicated. The aim of this study is to clarify the impact of perioperative vasopressor use on free flap outcomes.

Methods A systematic review was performed of all English-language articles that have compared free flap outcomes between patients who received vasopressors and those who did not. The outcome measures were total flap failure, pedicle thrombosis, and overall flap complications. Meta-analysis was performed using Mantel–Haenszel fixed-effects and DerSimonian and Laird random-effects models.

Results From a total of 130 citations, 14 studies representing 8,653 cases were analyzed. Majority of these did not find any negative effects of vasopressor use irrespective of dose, timing of administration, and method of delivery. Meta-analysis demonstrated that vasopressors were associated with less total flap failure overall (odds ratio, [OR]: 0.71, p = 0.05) and less pedicle thrombosis in head and neck reconstruction specifically (OR: 0.58, p = 0.02). Flap complication rates were similar across all defect types (OR: 0.97, p = 0.81) but appeared to be increased in breast reconstruction (OR: 1.46, p = 0.01).

Conclusion Perioperative vasopressor administration does not appear to be as detrimental to free flap survival as has been previously feared. Their role in optimizing hemodynamic stability may have a more beneficial effect on overall flap perfusion and in minimizing the complications of iatrogenic fluid overload.
Reducing Length of Stay after Microsurgical Breast Reconstruction with a Standardized Postoperative Protocol
Authors: DelMauro Matthew A. , Chen Kevin , Keller Alex
Published: May 2019

Background Despite widespread acceptance of enhanced recovery after surgery protocols in other surgical specialties, plastic surgery has been slow to adopt fast-track principles. Recently, however, studies have shown that patients undergoing microsurgical breast reconstruction may benefit from a comprehensive postoperative protocol.

Methods All microsurgical breast reconstructions with abdominal free flaps performed by the senior author (A.K.) at a single institution from June 2009 to December 2013 were reviewed. Demographic information (e.g., age, body mass index, and comorbidities), operative details (e.g., laterality, type of flap), and postoperative data (e.g., complications, length of stay) were collected from patients' medical records. The authors employed a universal comprehensive protocol that dictated all postoperative care as it relates to diet, ambulation, flap monitoring, anticoagulation, analgesia, venous thromboembolism, antibiotic prophylaxis, and discharge criteria.

Results During the study period, 161 patients underwent 289 free flaps. The average length of stay for all patients was 3.26 ± 1.19 days. The incidence of complications requiring return to the operating room was 4.35% (7 patients). The incidence of flap failure was 0.69% (2 of 289 flaps). Only one flap failure occurred after hospital discharge. Statistical analysis demonstrated that the presence of any complication requiring return to the operating room increased hospital course by an average of 1.37 days (p = 0.0027).

Conclusion The standardization of postoperative care for patients undergoing microsurgical breast reconstruction results in a short hospital length of stay without increasing the incidence of flap failure or postoperative complications requiring return to the operating room.
Modeling of silicon surface topographies induced by single nanosecond laser pulse induced melt-flows
Authors: Acosta-Zepeda C. , Saavedra P. , Bonse J. , Haro-Poniatowski E.
Published: May 2019

Irradiation with a single nanosecond laser pulse in the melting regime can result in a characteristic change in the surface morphology of crystalline silicon. This has been verified experimentally in a variety of situations, where dimple-shaped surface topographies are produced. In this work, the dimple height, depth, and width are modeled following and extending in a more rigorous manner the approach of Wood and Giles [Phys. Rev. B 23, 2923–2942 (1981)] and that of Schwarz-Selinger and coworkers [Phys. Rev. B 64, 155323 (2001)], upon varying the laser irradiation parameters such as peak energy density, pulse duration, and wavelength. This is achieved with numerical simulations of one-dimensional heat flow as input to the analytical fluid-flow equations.
Generalized Markov modeling of nonreversible molecular kinetics
Authors: Reuter Bernhard , Fackeldey Konstantin , Weber Marcus
Published: May 2019

Markov state models are to date the gold standard for modeling molecular kinetics since they enable the identification and analysis of metastable states and related kinetics in a very instructive manner. The state-of-the-art Markov state modeling methods and tools are very well developed for the modeling of reversible processes in closed equilibrium systems. On the contrary, they are largely not well suited to deal with nonreversible or even nonautonomous processes of nonequilibrium systems. Thus, we generalized the common Robust Perron Cluster Cluster Analysis (PCCA+) method to enable straightforward modeling of nonequilibrium systems as well. The resulting Generalized PCCA (G-PCCA) method readily handles equilibrium as well as nonequilibrium data by utilizing real Schur vectors instead of eigenvectors. This is implemented in the G-PCCA algorithm that enables the semiautomatic coarse graining of molecular kinetics. G-PCCA is not limited to the detection of metastable states but also enables the identification and modeling of cyclic processes. This is demonstrated by three typical examples of nonreversible systems.
Correction of torque transfer lag in magnetic coupling rheological test system
Authors: Li Bingfan , Liu Gang , Tong Yingze , Zhou Ying , Chen Lei , Teng Houxing , Lu Xingguo
Published: May 2019

In this study, a mathematical model for the magnetic coupling transmission process was set up to solve the problem of torque transfer lag in magnetic-coupled rheological testing systems. This model was developed on the basis of torque balance in a magnetic coupling rotatory rheometer test system, which considered friction loss for the jewel bearing, as well as the inertia of both the motor and fixture. Taking the HAAKE-MARS60 high-pressure rheometer as an example, the rheological properties of Newtonian fluid at the initial measuring stage under controlling constant stress conditions were tested to verify the accuracy of the model and using the model to modify the rheological test results. The results show that the load torque mainly influences the alternating frequency of the rotational speed and the hysteresis degree of the inner and outer magnetic rings, the larger the load torque, the greater the deviation of the magnetic coupling test results of the rotational rheometer. The results of the apparent viscosity test are modified under different loading conditions, and the rheological curves of the initial shear phase of the Newtonian fluid are coincident with the steady-state test results, showing the true viscosity of the Newtonian fluid, which conforms to the cognition of Newtonian fluid rheology being independent of time. The results of the initial start test of gelling crude oil were modified, the yield stress and yield time were reduced, and the lower the test temperature and the higher the shear rate, the more obvious the correction effect was. Under different shear rate conditions, the yield strain corresponding to the modified yield stress was close and the yield strain was approximately not changed with the shear rate. The results can provide a basis for understanding the rheological properties of materials in the start-up transient process under high pressure conditions.
Influence of crystallographic structure on polarization reversal in polycrystalline ferroelectric/ferroelastic materials
Authors: Schultheiß J. , Kungl H. , Koruza J.
Published: May 2019

Polarization reversal is the most fundamental physical process in ferroelectrics and directly or indirectly influences all functional properties of these materials. While this process is influenced by various intrinsic material’s properties and external boundary conditions, arguably one of the most dominant parameters is the material’s crystallographic structure. In this work, the influence of the crystallographic structure on the polarization reversal was investigated on the model ferroelectric system Pb(Zr,Ti)O3 using simultaneous time-dependent polarization and strain measurements. This method enabled one to extend the understanding beyond the widely investigated relationship between the structure and coercive fields. Polarization reversal was described by three regimes, which represent a sequence of well-defined non-180° and 180° switching events. The crystallographic structure was found to largely influence the mobility of the non-180° domain walls during the first switching regime, the amplitude of negative strain, and the broadness of the transition between the first and the second switching regimes, as well as the speed of the second (main) switching regime. The observed changes could be related to the amount of possible polarization directions, distribution of the local electric fields, and strain mismatch at domain wall junctions influenced by the lattice distortion. Moreover, activation fields for the first and the second regimes were experimentally determined for the investigated series of Pb(Zr,Ti)O3 samples. Besides providing insight into fundamental mechanisms of polarization reversal, these results can also be used as input parameters for micromechanical or stochastic models.
Algebraic-diagrammatic construction scheme for the polarization propagator including ground-state coupled-cluster amplitudes. I. Excitation energies
Authors: Hodecker Manuel , Dempwolff Adrian L. , Rehn Dirk R. , Dreuw Andreas
Published: May 2019

An ad hoc modification of the algebraic-diagrammatic construction (ADC) scheme for the polarization propagator is presented. Within this approach, all first-order Møller–Plesset correlation coefficients occurring in the second-order ADC secular matrix are replaced by amplitudes obtained from a coupled cluster doubles (CCD) calculation. This new hybrid method, denoted CCD-ADC(2), has been tested on a series of small diatomic and triatomic molecules and benchmarked with respect to Thiel’s benchmark set of medium-sized organic molecules. For the latter, the calculation of 134 singlet and 71 triplet states has shown that CCD-ADC(2) exhibits a mean error and standard deviation of 0.15 ± 0.34 eV for singlet states and 0.0 ± 0.17 eV for triplet states with respect to the provided theoretical best estimates, whereas standard ADC(2) has a mean error and standard deviation of 0.22 ± 0.30 eV for singlet and 0.12 ± 0.16 eV for triplet states. The corresponding extended second-order schemes ADC(2)-x and CCD-ADC(2)-x revealed accuracies of −0.70 ± 0.32 eV and −0.76 ± 0.33 eV for singlet states and −0.55 ± 0.20 eV and −0.67 ± 0.22 eV for triplet states, respectively. Furthermore, the investigation of excited-state potential energy curves along the dissociation of the N2 molecule has shown that the higher reliability of the ground-state CCD method as compared to MP2 is also inherent to the excited states. While the curves obtained at the ADC(2) level break down at around 2 Å, the ones obtained at CCD-ADC(2) remain reasonable up to about 3.5 Å.
Algebraic-diagrammatic construction scheme for the polarization propagator including ground-state coupled-cluster amplitudes. II. Static polarizabilities
Authors: Hodecker Manuel , Rehn Dirk R. , Norman Patrick , Dreuw Andreas
Published: May 2019

The modification of the algebraic-diagrammatic construction (ADC) scheme for the polarization propagator using ground-state coupled-cluster (CC) instead of Møller–Plesset (MP) amplitudes, referred to as CC-ADC, is extended to the calculation of molecular properties, in particular, dipole polarizabilities. Furthermore, in addition to CC with double excitations (CCD), CC with single and double excitations (CCSD) amplitudes can be used, also in the second-order transition moments of the ADC(3/2) method. In the second-order CC-ADC(2) variants, the MP correlation coefficients occurring in ADC are replaced by either CCD or CCSD amplitudes, while in the F/CC-ADC(2) and F/CC-ADC(3/2) variants, they are replaced only in the second-order modified transition moments. These newly implemented variants are used to calculate the static dipole polarizability of several small- to medium-sized molecules, and the results are compared to the ones obtained by full configuration interaction or experiment. It is shown that the results are consistently improved by the use of CC amplitudes, in particular, for aromatic systems such as benzene or pyridine, which have proven to be difficult cases for standard ADC approaches. In this case, the second-order CC-ADC(2) and F/CC-ADC(2) variants yield significantly better results than the standard third-order ADC(3/2) method, at a computational cost amounting to only about 1% of the latter.
Law of resistance in two-phase flows inside pipes
Authors: Dorao C. A. , Ryu J. , Fernandino M.
Published: May 2019

Two-phase micro- and mini-channel heat sinks are attractive for removing high heat fluxes, but the pressure drop in the two-phase flow regime can lead to prohibitively too high pumping power requirements. While significant research has been performed in the last decade for understanding the physical mechanisms controlling the heat transfer phenomenon, determining the two-phase flow pressure drop inside channels remains a longstanding question. In spite of the vast research performed, no agreement has been achieved in terms of the physical mechanisms controlling the two-phase pressure drop. Here, we measure the two-phase flow pressure drop in adiabatic conditions in a mini-channel considering the influence of the working pressure. The experiments show that the density ratio of the two-phase flow mixture plays a major role in controlling the pressure drop as the liquid phase enriched in the vapor phase increases the velocity of the flow. This finding minimizes the number of dimensionless groups required for predicting the two-phase flow pressure drop and is confirmed using independent experiments from the literature.
Fabrication and simulation investigation of zig-zag nanorod-structured graded-index anti-reflection coatings for LED applications
Authors: Liu Shizhao , Xu Yueming , Plawsky Joel L. , Raukas Madis , Piquette Alan , Lenef Alan
Published: May 2019

In this study, we report the fabrication, characterization, and modeling of a zigzag nanorod-structured graded-index antireflection coating fabricated by the oblique angle deposition (OAD) method. The optical properties of the reported coating were engineered by sculpting its composition and morphology using OAD, and the coating was designed to work with high-index, YAG:Ce ceramic phosphor plates. The coating enhances the normal-direction transmission of the phosphor plate over the broad visible-light spectrum. At 764 nm, the transmission is enhanced by 7.82%, compared to a potential maximum enhancement of 8.53%. For 633-nm light incident at 5°, the reported coating was measured to induce scattering loss of no greater than 1.27%. We developed a mathematical model that can use the OAD morphology information, developed from the film growth mechanism, as input parameters to simulate the optical properties of the nanostructured coatings. A finite-difference time-domain (FDTD) simulation was able to capture the polarization-dependent, antireflective performance of the coating, and the simulated transmission spectrum was in good agreement with both the measured spectrum and the spectrum calculated using the measured effective refractive indices in a transfer matrix formulation. In addition, the FDTD model was applied to predict the scattering losses. The simulation supports the experimental results and shows that the coating induces very weak scattering loss.
Magnetically excited granular matter in low gravity
Authors: Yu Peidong , Stärk Elmar , Blochberger Guido , Kaplik Martin , Offermann Malte , Tran Duong , Adachi Masato , Sperl Matthias
Published: May 2019

Due to the undesired impact of gravity, experimental studies of energy-dissipative gaseous systems are difficult to carry out on ground. In the past several years, we developed a series of experimental devices suitable for various kinds of microgravity platforms. The central idea adopted in our devices is to use long-range magnetic forces to excite all the particles within the system. Through the development of our devices, different component configurations, excitation protocols, and image-capturing methods have been tried and optimized to achieve best excitation and the maximum capability for data analysis.
BOUT++ nonlinear simulation for a comparative study with the measured 2D ELM structures in the KSTAR H-mode plasma
Authors: Kim M. , Park H. K. , Lee J. , Yun G. S. , Xu X. Q. , Bécoulet M.
Published: May 2019

Time-dependent nonlinear simulation using the BOUT++ 3-field model is performed for a study of edge localized mode (ELM) dynamics in KSTAR H-mode plasmas. The simulated results of the ELM evolution are directly compared with the 2D ELM structures, measured by electron cyclotron emission imaging systems, from the initial growth to crash phase. The simulation results are qualitatively in good agreement with the observations. Specifically, it is notable in simulation and experiment that higher-n modes in a quasi-steady state phase evolve into lower-n modes close to the ELM-crash in time. It suggests that lower-n modes may be responsible for the onset of the crash. A postanalysis supports that nonlinear mode coupling between toroidal harmonics may drive the lower-n mode.
Experimental investigation and SOLPS-ITER modeling of Ne-seeded radiative divertor H-modes plasma on EAST
Authors: Chen Jingbo , Yang Zhongshi , Coster David , Li Kedong , Wu Kai , Duan Yanmin , Wang Liang , Xu Jichan , Chen Xiahua , Ding Fang , Zang Qing , Wang Yumin , Wu Jinhua , Luo Guang-Nan ,   EAST Team
Published: May 2019

Both experimental modeling and numerical modeling were carried out on Experimental Advanced Superconductive Tokamak (EAST) to study the radiative divertor plasma behavior with neon (Ne) seeding. Steady H-mode radiation feedback control regimes (frad ∼ 18%–36%) were achieved by synergistic working of a divertor puff and supersonic molecular beam injection with Ne in the 2017 EAST campaign. Ne seeding effectively promoted divertor detachment while only causing a slight loss to the plasma stored energy in the experiment. To better understand the experimental result, analysis of the detachment process is introduced in this work. Two time slices namely before and after Ne seeding during the radiative divertor experiment in Shot #71021 were simulated by Scrape Off Layer Plasma Simulator (SOLPS)-ITER code. The simulation results for upstream plasma agreed well with the experiment, and the divertor profile agreed well on the outer targets when ignoring drifts. Radiation distribution was also calculated by SOLPS-ITER, showing that there was a high radiation region near the X-point, which is consistent with the experimental measurements.
Light-modulated valley-dependent birefringence of electron, the Brewster-like angles, and the giant magnetoresistance-like effect across a graphene-based junction
Authors: Cheng Renxiang , Zhou Xingfei
Published: May 2019

The transmission of electrons in graphene-based p-n and n-p-n junctions on a SiC substrate is investigated. When we irradiate a beam of off-resonant light on a p-n junction, the transmitted angles of electrons from different valleys are unequal, which is similar to the birefringence of light. This is due to the valley polarization induced by the competition between the SiC substrate and the off-resonant light. In addition, a light-modulated fully valley polarized current is realized. In the case of n-p-n junction, we find light-modulated valley-dependent Brewster-like angles at which the electron from one valley is totally transmitted, while the electron from the other valley is totally reflected due to the valley polarization. Furthermore, we propose a new type of tunneling resistance in a graphene-based n-p-n junction irradiated by the off-resonant light. The tunneling resistances have different magnitudes for the different orientations of light and even can show giant magnetoresistance-like effect due to the valley polarization. This is different from the traditional giant magnetoresistance effect in the ferromagnet-insulator-ferromagnet junction, where the spin degree of freedom plays a key role.
Plasma charge injection technology and its application to c-Si solar cells for field-effect passivation
Authors: Hwang Jeong-Mo
Published: May 2019

A plasma charge injection technology applicable for field-effect passivation in crystalline silicon solar cells is discussed. The technology uses an inert-gas plasma (helium, argon, N2, etc.) as a charge source and a DC bias to extract desired charges from a remote plasma source. A charging model is proposed, and it gives a good guideline to determine a proper charging operation condition for a desired injection charge density. The technology can introduce electric charges into a nitride–oxide or oxide–nitride–oxide passivation stack in a few hundred milliseconds with a charge density equivalent to or higher than that of Al2O3 in a range of 5 × 1012 to 8 × 1012 cm−2. Most-like charge injection mechanisms are discussed for both negative and positive charging. This technology uses a cheap inert-gas plasma which does not cause any parasitic film deposition nor any corrosion inside the chamber during the charging operation and, thus, does not require regular maintenance for chamber cleaning, which leads to a very low cost of ownership. This charging technology is promising for a low-cost alternative to the complex Al2O3 technology. This plasma charge injection can be another important application of the plasma technology among other well-known applications such as dry etching, thin-film deposition, sputtering, etc.
Raman investigation of layered ZrGeTe4 semiconductor
Authors: Gong Wentao , Li Liang , Gong Penglai , Zhou Yulan , Zhang Zhitao , Zhou Weichang , Wang Weike , Liu Ziran , Tang Dongsheng
Published: May 2019

This work presents a systematic study of phonon modes in a ZrGeTe4 layered semiconductor by Raman spectroscopy. Ten Raman characteristic peaks were detected and determined by density functional perturbation theory calculations. All Raman mode shifts exhibit a linear temperature dependence. The first-order temperature coefficients (χ) of the ZrGeTe4 Raman mode are in the range of −0.0058 cm−1/K to −0.01831 cm−1/K. Moreover, we demonstrate the strong anisotropic Raman response for linearly polarized excitation. The intensities of the observed Raman modes show periodic variation with the sample rotating under the angle-dependent and polarized Raman spectroscopy measurements, showing the high anisotropy of ZrGeTe4. Our results prove that ZrGeTe4 is a highly in-plane anisotropic 2D semiconductor, suggesting its potential application in nanoelectronic devices.
Polytype control of MoS2 using chemical bath deposition
Authors: Hedlund Jenny K. , Walker Amy V.
Published: May 2019

Molybdenum disulfide (MoS2) has a wide range of applications from electronics to catalysis. While the properties of single-layer and multilayer MoS2 films are well understood, controlling the deposited MoS2 polytype remains a significant challenge. In this work, we employ chemical bath deposition, an aqueous deposition technique, to deposit large area MoS2 thin films at room temperature. Using Raman spectroscopy and x-ray photoelectron spectroscopy, we show that the deposited MoS2 polytype can be changed from semiconducting 2H MoS2 on hydrophobic –CH3 and –CO2C6F5 terminated self-assembled monolayers (SAMs) to semimetallic 1T MoS2 on hydrophilic –OH and –COOH terminated SAMs. The data suggest that the deposition of MoS2 polytypes is controlled by the substrate surface energy. High surface energy substrates stabilize 1T MoS2 films, while 2H MoS2 is deposited on lower surface energy substrates. This effect appears to be general enabling the deposition of different MoS2 polytypes on a wide range of substrates.
Multiplexed readout of four qubits in 3D circuit QED architecture using a broadband Josephson parametric amplifier
Authors: Kundu Suman , Gheeraert Nicolas , Hazra Sumeru , Roy Tanay , Salunkhe Kishor V. , Patankar Meghan P. , Vijay R.
Published: May 2019

We propose and demonstrate a frequency-multiplexed readout scheme in 3D circuit-quantum electrodynamics (cQED) architecture. We use four transmon qubits coupled to individual rectangular cavities which are aperture-coupled to a common rectangular waveguide feedline. A coaxial to waveguide transformer at the other end of the feedline allows one to launch and collect the multiplexed signal. The reflected readout signal is amplified by an impedance-engineered broadband parametric amplifier with 380 MHz bandwidth. This provides us high fidelity single-shot readout of multiple qubits using compact microwave circuitry, an efficient way for scaling up to more qubits in 3D cQED.
Perdew-Zunger self-interaction correction: How wrong for uniform densities and large-Z atoms?
Authors: Santra Biswajit , Perdew John P.
Published: May 2019

Semilocal density functionals for the exchange-correlation energy of a many-electron system cannot be exact for all one-electron densities. In 1981, Perdew and Zunger (PZ) subtracted the fully nonlocal self-interaction error orbital-by-orbital, making the corrected functional exact for all collections of separated one-electron densities and making no correction to the exact functional. Although the PZ self-interaction correction (SIC) eliminates many errors of semilocal functionals, it is often worse for equilibrium properties of sp-bonded molecules and solids. Nonempirical semilocal functionals are usually designed to be exact for electron gases of uniform density and, thus, also make 0% error for neutral atoms in the limit of large atomic number Z, but PZ SIC is not so designed. For localized SIC orbitals, we show analytically that the local spin density approximation (LSDA)-SIC correlation energy per electron of the uniform gas in the high-density limit makes an error of −50% in the spin-unpolarized case and −100% in the fully spin-polarized case. Then we extrapolate from the Ne, Ar, Kr, and Xe atoms to estimate the relative errors of the PZ SIC exchange-correlation energies (with localized SIC orbitals) in the limit of large atomic number: about +5.5% for the LSDA-SIC and about −3.5% for nonempirical generalized gradient [Perdew-Burke-Ernzerhof (PBE)-SIC] and meta-generalized gradient strongly constrained and appropriately normed (SCAN)-SIC approximations. The SIC errors are considerably larger than those that have been estimated for LSDA-SIC by approximating the localized SIC orbitals for the uniform gas and may explain the errors of PZ SIC for equilibrium properties, opening the door to a generalized SIC that is more widely accurate.
Electroluminescence enhancement in mid-infrared InAsSb resonant cavity light emitting diodes for CO2 detection
Authors: Al-Saymari Furat A. , Craig Adam P. , Noori Yasir J. , Lu Qi , Marshall Andrew R. J. , Krier Anthony
Published: May 2019

In this work, we demonstrated a mid-infrared resonant cavity light emitting diode (RCLED) operating near 4.2 μm at room temperature, grown lattice-matched on a GaSb substrate by molecular beam epitaxy, suitable for CO2 gas detection. The device consists of a 1λ-thick microcavity containing an InAs0.90Sb0.1 active region sandwiched between two high contrast, lattice–matched AlAs0.08Sb0.92/GaSb distributed Bragg reflector (DBR) mirrors. The electroluminescence emission spectra of the RCLED were recorded over the temperature range from 20 to 300  K and compared with a reference LED without DBR mirrors. The RCLED exhibits a strong emission enhancement due to resonant cavity effects. At room temperature, the peak emission and the integrated peak emission were found to be increased by a factor of ∼70 and ∼11, respectively, while the total integrated emission enhancement was ∼×33. This is the highest resonant cavity enhancement ever reported for a mid-infrared LED operating at this wavelength. Furthermore, the RCLED also exhibits a superior temperature stability of ∼0.35  nm/K and a significantly narrower (10×) spectral linewidth. High spectral brightness and temperature stable emission entirely within the fundamental absorption band are attractive characteristics for the development of next generation CO2 gas sensor instrumentation.
Refractive index of lithium fluoride to 900 gigapascal and implications for dynamic equation of state measurements
Authors: Kirsch L. E. , Ali S. J. , Fratanduono D. E. , Kraus R. G. , Braun D. G. , Fernandez-Pañella A. , Smith R. F. , McNaney J. M. , Eggert J. H.
Published: May 2019

Lithium fluoride (LiF) is a unique crystal possessing the largest reported bandgap of any material and is predicted to remain transparent to visible light under stresses in excess of 1000 GPa. Dynamic compression experiments often utilize LiF as a window material to maintain stress on a sample while enabling direct measurements of interface velocity. However, typical velocimetry diagnostics measure changes in the optical path length; therefore, an accurate understanding of LiF’s equation of state and refractive index is needed. Here, we present a measurement of the LiF refractive index up to 900 GPa from a low-temperature ramp-compression experiment at the National Ignition Facility. To demonstrate propagation of optical uncertainty from this work to equation of state measurements, simulations in which a tin–LiF interface reaches a peak stress of 825 GPa show that the principal isentrope of tin can be determined up to 1450 GPa with a 1.2% uncertainty in density while considering uncertainties in the optical response of LiF.
On the generalized formulation of Debye shielding in plasmas
Authors: Livadiotis G.
Published: May 2019

It is shown that the Debye length formulation, for plasmas described by kappa distributions, depends on the polytropic index, rather than the parameter that labels and governs these distributions, the kappa index—in contrast to what it was previously derived. As a consequence, the ratio of the Debye length over the plasma oscillation period gives exactly the sound speed, instead of being proportional to the thermal speed; this ratio is generalized to the fast magnetosonic speed when the magnetic Debye length is considered, leading also to the development of the vector Debye length. Finally, as an application, we derive the Debye length values for the solar wind plasma near 1 AU, exhibiting clear distinction between slow and fast wind modes, while we provide insights into the connection between plasma and polytropic processes.
Interferences in locally resonant sonic metamaterials formed from Helmholtz resonators
Authors: Peiró-Torres María Pilar , Castiñeira-Ibáñez Sergio , Redondo Javier , Sánchez-Pérez Juan Vicente
Published: May 2019

The emergence of materials artificially designed to control the transmission of waves, generally called metamaterials, has been a hot topic in the field of acoustics for several years. The design of these metamaterials is usually carried out by overlapping different wave control mechanisms. An example of this trend is the so-called Locally Resonant Sonic Materials, being one of them the Phononic Crystals with a local resonant structure. These metamaterials are formed by sets of isolated resonators in such a way that the control of the waves is carried out by resonances and by the existence of Bragg bandgaps, which appear due to the ordered distribution of the resonators. Their use is based on the creation of resonance peaks to form additional nontransmission bands mainly in the low frequency regime, usually below the first Bragg frequency. The coupling of both gaps has been made in some cases, but it is not always so. In this work, using a periodic structure formed by Helmholtz resonators, we report the existence of interferences between the resonances and the Bragg bandgaps when they are working in nearby frequency ranges, so that they prevent the coupling of both gaps. We explain their physical principles and present possible solutions to mitigate them. To this end, we have developed numerical models based on the finite element method, and the results have been verified by means of accurate experimental results obtained under controlled conditions.
Strain related relaxation of the GaAs-like Raman mode selection rules in hydrogenated GaAs1−xNx layers
Authors: Giulotto E. , Geddo M. , Patrini M. , Guizzetti G. , Sharma M. S. , Capizzi M. , Polimeni A. , Pettinari G. , Rubini S. , Felici M.
Published: May 2019

The GaAs-like longitudinal-optical (LO) phonon frequency in hydrogenated GaAs1−xNx (x = 0.01) layers—with different H doses and similar low-energy irradiation conditions—was investigated by micro-Raman measurements in different scattering geometries and compared with those of epitaxial GaAs and as-grown GaAs1−xNx reference samples. A relaxation of the GaAs selection rules was observed, to be explained mainly on the basis of the biaxial strain affecting the layers. The evolution of the LO phonon frequency with increasing hydrogen dose was found to heavily depend on light polarization, thus suggesting that a linear relation between strain and the frequency of the GaAs-like LO phonon mode should be applied with some caution. Moreover, photoreflectance measurements in fully passivated samples of identical N concentration show that the blueshift of the GaAs-like LO frequency, characteristic of the hydrogenated structures, is dose-dependent and strictly related to the strain induced by the specific type of the dominant N-H complexes. A comparison of photoreflectance results with the finite element method calculations confirms that this dependence on the H dose is due to the gradual replacement of the N-2H complexes responsible for the electronic passivation of N with N-3H complexes, which are well known to induce an additional and sizeable lattice expansion.
Effect of AlPO4 join concentration on optical properties and radiation hardening performance of Yb-doped Al2O3-P2O5-SiO2 glass
Authors: Wang Fan , Shao Chongyun , Yu Chunlei , Wang Shikai , Zhang Lei , Gao Guojun , Hu Lili
Published: May 2019

A series of Yb-doped silica glasses containing equimolar amounts of P2O5 and Al2O3 were prepared using a sol–gel method combined with high-temperature sintering. Raman spectroscopy confirmed the formation of AlPO4 join with a P/Al ratio of 1. However, for a P/Al ratio slightly larger than 1, both the AlPO4 join and P=O bond are formed. Based on the absorption, emission spectra, and electron paramagnetic resonance measurements, it was determined that the increase of the AlPO4 join concentration in Yb-doped silica glass leads to (i) a decrease in the refractive index with a factor of 1.1005 × 10−4 (which allows for a low numerical aperture facilitating single-mode laser), (ii) the sustained spectroscopic properties of Yb3+, (iii) a decrease in Yb cluster concentration, and (iv) an improved radiation hardening performance (beneficial to high-power space lasers). These results suggest that Yb-doped Al2O3-P2O5-SiO2 glass with an appropriate concentration of AlPO4 join has potential applications in high-power space fiber lasers.
Vector solutions for two coupled Schrödinger equations on Riemannian manifolds
Authors: Chen Yan-Hong , Zou Wenming
Published: May 2019

We are interested in two coupled nonlinear Schrödinger equations on a smooth compact boundaryless Riemannian manifold, which arises from Bose-Einstein condensates and nonlinear optics theory. The existence of least energy solutions, multiplicity of positive solutions, as well as synchronized vector solutions is obtained.
Reducing background signals in SERS detection and imaging
Authors: Kim Meeri
Published: May 2019

A new article describes mathematical methods for mitigating the influence of Raman or fluorescent background signals for biological applications of SERS tags.
Prenatal androgen excess alters the uterine peroxisome proliferator-activated receptor (PPAR) system
Authors: Ferreira Silvana R. , Vélez Leandro M. , F. Heber Maria , Abruzzese Giselle A. , Motta Alicia B.
Published: May 2019

It is known that androgen excess induces changes in fetal programming that affect several physiological pathways. Peroxisome proliferator-activated receptors (PPARs) α, δ and γ are key mediators of female reproductive functions, in particular in uterine tissues. Thus, we aimed to study the effect of prenatal hyperandrogenisation on the uterine PPAR system. Rats were treated with 2mg testosterone from Day 16 to 19 of pregnancy. Female offspring (PH group) were followed until 90 days of life, when they were killed. The PH group exhibited an anovulatory phenotype. We quantified uterine mRNA levels of PPARα (Ppara), PPARδ (Ppard), PPARγ (Pparg), their regulators peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Ppargc1a) and nuclear receptor co-repressor 1 (Ncor1) and cyclo-oxygenase (COX)-2 (Ptgs2), and assessed the lipid peroxidation (LP) index and levels of glutathione (GSH) and prostaglandin (PG) E2. The PH group showed decreased levels of all uterine PPAR isoforms compared with the control group. In addition, PGE2 and Ptgs2 levels were increased in the PH group, which led to a uterine proinflammatory environment, as was LP, which led to a pro-oxidant status that GSH was not able to compensate for. These results suggest that prenatal exposure to androgen excess has a fetal programming effect that affects the gene expression of PPAR isoforms, and creates a misbalanced oxidant–antioxidant state and a proinflammatory status.
Cell contact and Nf2/Merlin-dependent regulation of TEAD palmitoylation and activity
Authors: Kim Nam-Gyun , Gumbiner Barry M.
Published: May 2019

Significance

The Hippo signaling pathway regulates cell proliferation in response to cell contact and a variety of other extracellular stimuli. It controls the activity and nuclear localization of cotranscriptional activator YAP, which interacts with DNA binding transcription factor TEAD, for the expression of target genes involved in cell proliferation. We show here that the expression level and transcriptional activity of TEAD are actively controlled by cell density through the modulation of its palmitoylation status. TEAD palmitoylation is controlled via fatty acid synthase and depalmitoylases in response to cell density. Our study indicates that the regulation of palmitoylation status is a potential target for controlling TEAD-dependent processes, perhaps including cancer growth.
Molecular dynamics simulation-guided drug sensitivity prediction for lung cancer with rare
EGFR
mutations
Authors: Ikemura Shinnosuke , Yasuda Hiroyuki , Matsumoto Shingo , Kamada Mayumi , Hamamoto Junko , Masuzawa Keita , Kobayashi Keigo , Manabe Tadashi , Arai Daisuke , Nakachi Ichiro , Kawada Ichiro , Ishioka Kota , Nakamura Morio , Namkoong Ho , Naoki Katsuhiko , Ono Fumie , Araki Mitsugu , Kanada Ryo , Ma Biao , Hayashi Yuichiro , Mimaki Sachiyo , Yoh Kiyotaka , Kobayashi Susumu S. , Kohno Takashi , Okuno Yasushi , Goto Koichi , Tsuchihara Katsuya , Soejima Kenzo
Published: May 2019

Significance

A variety of rare mutations account for 10–20% of
EGFR
mutations in nonsmall cell lung cancer. However, due to high diversity, proper medication for patients with such mutations is impossible in daily clinic. To appropriately treat lung cancer patients harboring such rare
EGFR
mutations, a robust prediction model to predict sensitivities of rare
EGFR
mutants to existing drugs is strongly needed. Using molecular dynamics simulation-based model, we successfully predicted diverse sensitivities of EGFR exon 20 insertion mutants to existing inhibitors. The findings suggest the usefulness of in silico simulation to overcome mutation diversity at a clinically relevant level. The present in silico model will help in selecting effective drugs for these patients.
Indigenous knowledge networks in the face of global change
Authors: Cámara-Leret Rodrigo , Fortuna Miguel A. , Bascompte Jordi
Published: May 2019

Significance

The knowledge of nonliterate societies may vanish in silence jeopardizing indigenous peoples’ livelihoods. Yet, this cultural component is missed by studies on ecosystem services that have historically emphasized the biological dimension. Here we fill this gap by introducing indigenous knowledge networks representing the wisdom of indigenous people on plant species and the services they provide. This approach allows us to assess how knowledge held by 57 Neotropical indigenous communities is structured locally and regionally, how it is influenced by turnover in biological and cultural heritage, and how the progressive loss of biocultural heritage may undermine the resilience of these communities.
A homeotic shift late in development drives mimetic color variation in a bumble bee
Authors: Tian Li , Rahman Sarthok Rasique , Ezray Briana D. , Franzini Luca , Strange James P. , Lhomme Patrick , Hines Heather M.
Published: May 2019

Natural phenotypic radiations, with their high diversity and convergence, are well-suited for informing how genomic changes translate to natural phenotypic variation. New genomic tools enable discovery in such traditionally nonmodel systems. Here, we characterize the genomic basis of color pattern variation in bumble bees (Hymenoptera, Apidae,
Bombus
), a group that has undergone extensive convergence of setal color patterns as a result of Müllerian mimicry. In western North America, multiple species converge on local mimicry patterns through parallel shifts of midabdominal segments from red to black. Using genome-wide association, we establish that a c
is
-regulatory locus between the abdominal fate-determining
Hox
genes,
abd-A
and
Abd-B
, controls the red–black color switch in a western species,
Bombus melanopygus
. Gene expression analysis reveals distinct shifts in
Abd-B
aligned with the duration of setal pigmentation at the pupal–adult transition. This results in atypical anterior
Abd-B
expression, a late developmental homeotic shift. Changing expression of
Hox
genes can have widespread effects, given their important role across segmental phenotypes; however, the late timing reduces this pleiotropy, making
Hox
genes suitable targets. Analysis of this locus across mimics and relatives reveals that other species follow independent genetic routes to obtain the same phenotypes.
Mutant p53 amplifies a dynamin-1/APPL1 endosome feedback loop that regulates recycling and migration
Authors: Lakoduk Ashley M. , Roudot Philippe , Mettlen Marcel , Grossman Heather M. , Schmid Sandra L. , Chen Ping-Hung
Published: May 2019

Multiple mechanisms contribute to cancer cell progression and metastatic activity, including changes in endocytic trafficking and signaling of cell surface receptors downstream of gain-of-function (GOF) mutant p53. We report that dynamin-1 (Dyn1) is up-regulated at both the mRNA and protein levels in a manner dependent on expression of GOF mutant p53. Dyn1 is required for the recruitment and accumulation of the signaling scaffold, APPL1, to a spatially localized subpopulation of endosomes at the cell perimeter. We developed new tools to quantify peripherally localized early endosomes and measure the rapid recycling of integrins. We report that these perimeter APPL1 endosomes modulate Akt signaling and activate Dyn1 to create a positive feedback loop required for rapid recycling of EGFR and β1 integrins, increased focal adhesion turnover, and cell migration. Thus, Dyn1- and Akt-dependent perimeter APPL1 endosomes function as a nexus that integrates signaling and receptor trafficking, which can be co-opted and amplified in mutant p53–driven cancer cells to increase migration and invasion.
Impact of fast ions on density peaking in JET: fluid and gyrokinetic modeling
Authors: Eriksson F , Oberparleiter M , Skyman A , Nordman H , Strand P , Salmi A , Tala T
Published: May 2019

The effect of fast ions on turbulent particle transport, driven by ion temperature gradient (ITG)/trapped electron mode turbulence, is studied. Two neutral beam injection (NBI) heated JET discharges in different regimes are analyzed at the radial position ρ

t
 = 0.6, one of them an L-mode and the other one an H-mode discharge. Results obtained from the computationally efficient fluid model EDWM and the gyro-fluid model TGLF are compared to linear and nonlinear gyrokinetic GENE simulations as well as the experimentally obtained density peaking. In these models, the fast ions are treated as a dynamic species with a Maxwellian background distribution. The dependence of the zero particle flux density gradient (peaking factor) on fast ion density, temperature and corresponding gradients, is investigated. The simulations show that the inclusion of a fast ion species has a stabilizing influence on the ITG mode and reduces the peaking of the main ion and electron density profiles in the absence of sources. The models mostly reproduce the experimentally obtained density peaking for the L-mode discharge whereas the H-mode density peaking is significantly underpredicted, indicating the importance of the NBI particle source for the H-mode density profile.
Topological time crystals
Authors: Giergiel Krzysztof , Dauphin Alexandre , Lewenstein Maciej , Zakrzewski Jakub , Sacha Krzysztof
Published: May 2019

By analogy with the formation of space crystals, crystalline structures can also appear in the time domain. While in the case of space crystals we often ask about periodic arrangements of atoms in space at a moment of a detection, in time crystals the role of space and time is exchanged. That is, we fix a space point and ask if the probability density for detection of a system at this point behaves periodically in time. Here, we show that in periodically driven systems it is possible to realize topological insulators, which can be observed in time. The bulk-edge correspondence is related to the edge in time, where edge states localize. We focus on two examples: Su-Schrieffer-Heeger model in time and Bose Haldane insulator which emerges in the dynamics of a periodically driven many-body system.