bluuebunny/crossref_metadata_2025 huggingface dataset:
Hard x-ray standing-wave photoemission insights into the structure of an epitaxial Fe/MgO multilayer magnetic tunnel junction
Authors: Conlon C. S. , Conti G. , Nemšák S. , Palsson G. , Moubah R. , Kuo C.-T. , Gehlmann M. , Ciston J. , Rault J. , Rueff J.-P. , Salmassi F. , Stolte W. , Rattanachata A. , Lin S.-C. , Keqi A. , Saw A. , Hjörvarsson B. , Fadley C. S.
Published: August 2019

The Fe/MgO magnetic tunnel junction is a classic spintronic system, with current importance technologically and interest for future innovation. The key magnetic properties are linked directly to the structure of hard-to-access buried interfaces, and the Fe and MgO components near the surface are unstable when exposed to air, making a deeper probing, nondestructive, in-situ measurement ideal for this system. We have thus applied hard x-ray photoemission spectroscopy (HXPS) and standing-wave (SW) HXPS in the few kilo-electron-volt energy range to probe the structure of an epitaxially grown MgO/Fe superlattice. The superlattice consists of 9 repeats of MgO grown on Fe by magnetron sputtering on an MgO(001) substrate, with a protective Al2O3 capping layer. We determine through SW-HXPS that 8 of the 9 repeats are similar and ordered, with a period of 33 ± 4 Å, with the minor presence of FeO at the interfaces and a significantly distorted top bilayer with ca. 3 times the oxidation of the lower layers at the top MgO/Fe interface. There is evidence of asymmetrical oxidation on the top and bottom of the Fe layers. We find agreement with dark-field scanning transmission electron microscope (STEM) and x-ray reflectivity measurements. Through the STEM measurements, we confirm an overall epitaxial stack with dislocations and warping at the interfaces of ca. 5 Å. We also note a distinct difference in the top bilayer, especially MgO, with possible Fe inclusions. We thus demonstrate that SW-HXPS can be used to probe deep buried interfaces of novel magnetic devices with few-angstrom precision.
Evaluating link significance in maintaining network connectivity based on link prediction
Authors: Qi Mingze , Tan Suoyi , Deng Hongzhong , Wu Jun
Published: August 2019

Evaluating the significance of nodes or links has always been an important issue in complex networks, and the definition of significance varies with different perspectives. The significance of nodes or links in maintaining the network connectivity is widely discussed due to its application in targeted attacks and immunization. In this paper, inspired by the weak tie phenomenon, we define the links’ significance by the dissimilarity of their endpoints. Some link prediction algorithms are introduced to define the dissimilarity of nodes based solely on the network topology. Experiments in synthetic and real networks demonstrate that the method is especially effective in the networks with higher clustering coefficients.
Fock-space multireference coupled cluster calculations of Auger energies of noble gas elements using relativistic spinors
Authors: Chaudhuri Rajat K. , Chattopadhyay Sudip
Published: August 2019

We report the Auger and Coster-Kronig transition energies (related to double ionization potentials) of noble gas elements obtained using the Fock-space multireference coupled cluster (FSMRCC) method with relativistic spinors. The resulting Auger and Coster-Kronig lines are found to be in agreement with the experimental data and with other reference theoretical estimates. To the best of our knowledge, no prior report of relativistic calculations is available for Auger transition energies at the FSMRCC level of theory. The ionization potentials resulted from this method with no extra cost are also found to be in agreement with experiment, particularly the outer-valence ones. Interestingly, the FSMRCC and the multiconfiguration Dirac-Fock calculations exhibit an inversion in the 3P energy levels of the xenon atom for N4,5–O23O23 Auger transitions, where the 3Pj state energies appear in the order J = 1, 0, 2, a feature which can be verified experimentally.
Surface impedance and skin depth for transverse waves in temperature anisotropic unmagnetized plasma
Authors: Aman-ur-Rehman  , Khokhar Tajammal H. , Shah H. A. , Murtaza G.
Published: August 2019

The anomalous skin depth has been calculated using the surface impedance for the transverse waves in unmagnetized plasma. The effect of temperature anisotropy on the surface impedance and the anomalous skin effect have been studied using the kinetic model for an electromagnetic wave normally impinging on a plasma surface filling the half space z > 0. It is noted that the maximum value of the real part of the surface impedance occurs when ωωpe=π8vt||cT⊥T||. The imaginary part, however, is not affected by the temperature anisotropy parameter significantly. It has been found that in the case of anisotropic plasma, the skin depth varies as ω−1 in the low frequency regime which is different from isotropic plasma where the skin depth varies as ω−1/3. In the low frequency regime, the skin depth first increases with the temperature anisotropy and then starts decreasing with an increase in the temperature anisotropy parameter η. However, in the large frequency regime, the skin depth is inversely proportional to the temperature anisotropy parameter η. These results have been confirmed by numerically plotting the surface impedance and the skin depth for a wide range of plasma parameters.
Contributions of force field interaction forms to Green-Kubo viscosity integral in n-alkane case
Authors: Kondratyuk N.
Published: August 2019

Decades of molecular simulation history proved that the Green-Kubo method for shear viscosity converges without any problems in atomic and simple molecular liquids, unlike liquids with high values of viscosity. In the case of highly viscous liquids, the time decomposition method was developed in 2015 by Maginn and co-authors [Y. Zhang, A. Otani, and E. J. Maginn, J. Chem. Theory Comput. 11, 3537–3546 (2015)] which allows us to improve the convergence of the Green-Kubo integral. In this paper, the contributions of intramolecular and intermolecular force field parts to the viscosity integral are discovered to gain the understanding of the Green-Kubo method. The n-alkanes from n-ethane to n-pentane at 330 K in the optimized potentials for liquid simulations-all atom force field are used as reference models. The dependencies of these contributions and decay times of the corresponding correlation functions on the chain length are observed. The nonequilibrium simulations are carried out to verify the Green-Kubo results. The obtained values of viscosity are compared with experimental data.
Thermoluminescence and phototransferred thermoluminescence dosimetry on mobile phone protective touchscreen glass
Authors: Chandler J. R. , Sholom S. , McKeever S. W. S. , Hall H. L.
Published: August 2019

Thermoluminescence and phototransferred thermoluminescence measurements of protective glass from smartphones are described. Samples of Gorilla Glass were examined from nine different manufacturers and 40 different phone models. Additionally, 12 glasses believed to be original equipment manufacturer replacements, as well as three glass samples from U.S. finishers, were also studied. Altogether, 99 different Gorilla Glass samples were examined. The radiation-induced thermoluminescence signal produced glow curve shapes specific to the Gorilla Glass generations and could be used to distinguish between them. A background thermoluminescence (and phototransferred thermoluminescence) signal was found in all unirradiated samples. Its intensity and shape were found to be dependent on the Gorilla Glass generation, phone manufacturer, and phone model. The background signal was demonstrated to be produced by ultraviolet light exposure; the shape of the background signal was able to be reproduced by the combined exposure to a broad-spectrum solar simulator and a 302 nm ultraviolet light source. The background signal intensity was found to vary with the location from which it was taken on the glass. It was also found to be dependent on the depth within the Gorilla Glass due to absorption of the ultraviolet light as it traversed the medium. Removal of the glasses’ surface layers was found to be an inadequate method for removing the background signal. In some samples, the background signal intensity was large enough to significantly contribute to the total thermoluminescence (and phototransferred thermoluminescence) signal; therefore, a matrix deconvolution method was introduced to separate the background signal and radiation-induced signal. This method was found to enable dose reconstruction using the radiation-induced signal alone.
A solid-state wind-energy transformer
Authors: Epstein Richard I.
Published: August 2019

We show that a solid-state apparatus with no moving parts can harvest electrical power from the wind. This apparatus, a Solid-state Wind-Energy Transformer (SWET), uses coronal discharge to create negative air ions, which the wind carries away from the SWET. The SWET harnesses the wind-induced currents and voltages to produce electrical power. We report on the operation of a low-power, proof-of-concept SWET. This device consists of a number of parallel electrical wires: “emitter wires,” which have numerous, sharp coronal emitters attached to it, and bare “attractor wires.” When a negative bias voltage is applied to the emitter wires relative to the attractor wires, the coronal emitters generate negative ions. The wind carries off these ions, which eventually settle to ground. The power imparted to the ions by the wind is extracted from the current returning to the SWET from the ground. This proof-of-concept SWET demonstrates that it is possible to generate net electrical power from the wind using only air ions. We estimate that SWET can be scaled up to commercially interesting powers by increasing the number and length of emitter and attractor wires and by controlling the bias voltage. SWETs have the potential to produce large amounts of electrical power at low costs with little negative environmental impact.
Wall turbulence response to surface cooling and formation of strongly stable stratified boundary layers
Authors: Atoufi Amir , Scott K. Andrea , Waite Michael L.
Published: August 2019

This paper investigates the processes by which stable boundary layers are formed through strong surface cooling imposed on neutrally stratified wall-bounded turbulence using high-resolution direct numerical simulation at a moderate Reynolds number. The adjustment of the flow to the imposed strong surface cooling is investigated. We further focus on a strongly stable case where turbulence partially collapses. We show that, due to a significant reduction in turbulence production, turbulence becomes patchy, with a band of turbulence coexisting with quiet regions. The nature of the quiet regions, which are often characterized as laminar, is investigated and shown to be consistent with viscously coupled stratified turbulence. The one-dimensional longitudinal streamwise velocity spectrum exhibits kx−5 and kx−3 behavior in the buffer and logarithmic layers, respectively, adjacent to an active region of three-dimensional turbulence with a kx−5/3 spectrum. Scenarios for turbulence recovery from such a patchy state are also discussed. We show that the presence of outer layer turbulence above z+ ≈ 300 is a key requirement for recovery. For higher values of stratification, it is shown that inner layer turbulence is damped entirely and outer layer turbulence is damped subsequently.
Lagrangian statistics of pressure fluctuation events in homogeneous isotropic turbulence
Authors: Bappy Mehedi , Carrica Pablo M. , Buscaglia Gustavo C.
Published: August 2019

Homogeneous and isotropic turbulent fields obtained from two direct numerical simulation databases (with Reλ equal to 150 and 418) were seeded with point particles that moved with the local fluid velocity to obtain Lagrangian pressure histories. Motivated by cavitation inception modeling, the statistics of events in which such particles undergo low-pressure fluctuations were computed, parameterized by the amplitude of the fluctuations and by their duration. The main results are the average frequencies of these events and the probabilistic distribution of their duration, which are of predictive value. A connection is also established between these average frequencies and the pressure probability density function, thus justifying experimental methods proposed in the literature. Further analyses of the data show that the occurrence of very-low-pressure events is highly intermittent and is associated with wormlike vortical structures of length comparable to the integral scale of the flow.
Vortex-induced vibration of a cooled circular cylinder
Authors: Garg Hemanshul , Soti Atul Kumar , Bhardwaj Rajneesh
Published: August 2019

We numerically investigate vortex-induced vibration of a cooled circular cylinder in the presence of thermal buoyancy. We employ an in-house fluid-structure interaction solver based on a sharp-interface immersed boundary method. The cylinder is elastically mounted and is free to vibrate transversely to the flow direction. The surface of the cylinder is prescribed at a temperature lower than that of the fluid, and the gravity is aligned opposite to the flow direction. Numerical simulations are carried out for the following parameters: Reynolds number, Re = 150, Prandtl number, Pr = 7.1, Richardson number, Ri = [−1, 0], mass ratio, m = 2, and reduced velocity, UR = [3, 20]. The oscillation amplitude of the cylinder is larger in the presence of the thermal buoyancy for 4 < UR < 15. The amplitude is maximum at UR = 11 and is around ≈1D* in the presence of the thermal buoyancy, where D* is the diameter of the cylinder. However, this amplitude is ≈0.6D* at UR = 4 in the absence of the thermal buoyancy. The lock-in (synchronization) region is obtained for a wider range of UR in the presence of the thermal buoyancy. In the presence of the thermal buoyancy, along with a dominating vortex shedding frequency, we obtain multiple weak as well as strong even and odd harmonics along with subharmonics of the fundamental frequency in the lift signal. However, the secondary frequencies are limited to only a weak third harmonic of the fundamental frequency in the absence of the thermal buoyancy. We observe elongated as well as wider vortices and isotherms in the presence of the thermal buoyancy although the vortex shedding mode remains “2S.” Our results show that there exists a critical minimum absolute value of Ri in order to achieve the lock-in and this value increases with UR.
Valley dynamics of different trion species in monolayer WSe2
Authors: Fu Jiyong , Cruz Junio M. R. , Qu Fanyao
Published: August 2019

We develop a model, taking into account optically inactive excitonic dark states, of both spin-forbidden and momentum-forbidden types, to explore valley dynamics of different trion species in monolayer WSe2. We observe two distinct regimes, determined by two typical bright-dark scattering processes, i.e., the spin-flip and spin-conserving ones. When the spin-flip scattering is comparable to the spin-conserving one, we find that the valley polarizations (VPs) of all excitonic states including excitons and singlet and triplet trions are copolarized with respect to the excitation laser, consistent with available experimental measurements. Interestingly, when the spin-conserving scattering dominates over the spin-flip one, we observe the reversal of VP of the singlet trion. This fascinating valley control opens the door to an envisaged valley field-effect transistor (FET) (an analog of spin FET). Furthermore, we reveal that the reversed VP strengthens until it becomes stabilized, offering a promising platform for coherent control of valley pseudospin. Our findings should stimulate experiments probing the VP reversal in samples with strong spin-conserving scattering.
Predicting noise-induced critical transitions in bistable systems
Authors: Ma Jinzhong , Xu Yong , Li Yongge , Tian Ruilan , Kurths Jürgen
Published: August 2019

Critical transitions from one dynamical state to another contrasting state are observed in many complex systems. To understand the effects of stochastic events on critical transitions and to predict their occurrence as a control parameter varies are of utmost importance in various applications. In this paper, we carry out a prediction of noise-induced critical transitions using a bistable model as a prototype class of real systems. We find that the largest Lyapunov exponent and the Shannon entropy can act as general early warning indicators to predict noise-induced critical transitions, even for an earlier transition due to strong fluctuations. Furthermore, the concept of the parameter dependent basin of the unsafe regime is introduced via incorporating a suitable probabilistic notion. We find that this is an efficient tool to approximately quantify the range of the control parameter where noise-induced critical transitions may occur. Our method may serve as a paradigm to understand and predict noise-induced critical transitions in multistable systems or complex networks and even may be extended to a broad range of disciplines to address the issues of resilience.
Study of electronic transport properties in AlGaN/AlN/GaN/AlGaN double-heterojunction transistor
Authors: Li Yao , Zhang Jinfeng
Published: August 2019

The electronic transport properties in AlGaN/AlN/GaN/AlGaN double heterostructures are investigated by an analytical model, considering the effect of the modified Fang-Howard wave function. The alloy disorder scattering is assumed to be eliminated by the introduction of an AlN insertion layer, and the rest five possible scattering mechanisms, acoustic deformation potential scattering, piezoelectric field scattering, polar optical phonons scattering, interface roughness scattering, and dislocation scattering, are taken into consideration in the calculation. The relations of two-dimensional electron gas (2DEG) density and mobility with alloy composition in the top AlGaN barrier layer and AlGaN buffer layer and the channel thickness are estimated and discussed. Finally, we compare the temperature dependences of the 2DEG mobility in Al0.25Ga0.75N/AlN/GaN/Al0.05Ga0.95N double heterostructures and in the conventional Al0.25Ga0.75N/AlN/GaN single heterostructures and explain them with detailed scattering processes.
Fast control of dissipation in a superconducting resonator
Authors: Sevriuk V. A. , Tan K. Y. , Hyyppä E. , Silveri M. , Partanen M. , Jenei M. , Masuda S. , Goetz J. , Vesterinen V. , Grönberg L. , Möttönen M.
Published: August 2019

We report on fast tunability of an electromagnetic environment coupled to a superconducting coplanar waveguide resonator. Namely, we utilize a recently developed quantum-circuit refrigerator (QCR) to experimentally demonstrate a dynamic tunability in the total damping rate of the resonator up to almost two orders of magnitude. Based on the theory, it corresponds to a change in the internal damping rate by nearly four orders of magnitude. The control of the QCR is fully electrical, with the shortest implemented operation times in the range of 10 ns. This experiment constitutes a fast active reset of a superconducting quantum circuit. In the future, a similar scheme can potentially be used to initialize superconducting quantum bits.
Radiation-damage in multi-layered zircon: Mechanical properties
Authors: Beirau Tobias , Oliver Warren C. , Reissner Claudia E. , Nix William D. , Pöllmann Herbert , Ewing Rodney C.
Published: August 2019

Nanoindentation high-resolution mapping has been used to probe the mechanical properties [elastoplastic factor (S2/P, where S is the contact stiffness and P is the load), indentation hardness (H), and elastic modulus (E)] of a natural, highly zoned zircon (ZrSiO4). The zoning, on a scale of ∼ 5 to 400 μm, is due to variations in the U and Th concentrations, resulting in a range of α-decay event doses of ∼ 3.7× to 7.5 × 1018 α-decays/g. Thus, this single, zoned zircon crystal can be used to investigate the effects of α-decay radiation-damage on mechanical properties. The results also illustrate how multilayered ceramics accommodate volume expansion and change in mechanical properties as a function of radiation dose. Further, the detailed investigation of fractures in the lesser damaged, higher crystalline domains provides a better understanding of crack propagation in the initially crystalline material due to the strain induced by heterogeneous damage distribution. This is an important consideration in designing materials for the immobilization of plutonium from dismantled nuclear weapons, as plutonium decays by α-decay events. The directly measurable stiffness2/load (S2/P) provides a useful estimate of the degree of radiation-damage. The evolution of E provides experimental evidence for the predicted second percolation transition that denotes the end of percolation of the crystalline fraction.
Effect of salinity and food concentration on competition between Brachionus plicatilis Müller, 1786 and Brachionus calyciflorus Pallas, 1776 (Rotifera)
Authors: Ferrando N. S. , Nandini S. , Claps M. C. , Sarma S. S. S.
Published: August 2019

Natural populations of planktonic rotifers are affected by salinity and food density, among other stressors. Moreover, competition among congeneric species limits the abundance of certain rotifers in ecosystems without spatial heterogeneity and environmental fluctuations. We isolated Brachionus plicatilis and Brachionus calyciflorus from Salado River basin waterbodies and studied the demographic characteristics and competition between them at three salinity levels (0.75, 1.75 and 2.75gL–1 NaCl) and at two food concentrations (0.1×106 and 0.5×106 cells mL–1 Chlorella vulgaris). The lowest salinity level proved to be unfavourable for the population growth of B. plicatilis, but at higher salinity levels the growth was similar to that of controls (without competition), even in the presence of the competitor and at either food concentration. By contrast, the competitor almost always decreased the density of B. calyciflorus. Salinity greatly affected the peak density of B. plicatilis, whereas the effects of salinity and competition on B. calyciflorus were similar. Biomass was inversely related to salinity for both species, and was significantly affected by competition in B. plicatilis. These results show that B. calyciflorus is more adversely affected than B. plicatilis by competition and high salinity, and explain why both species can coexist in eutrophic saline lowland rivers and pampean shallow lakes.
Using network analysis to identify keystone species in the food web of Haizhou Bay, China
Authors: Wu Jiaying , Liu Yang , Sui Haozhi , Xu Binduo , Zhang Chongliang , Ren Yiping , Xue Ying
Published: August 2019

Keystone species play critical roles in ecological communities and ecosystem functions by interacting directly or indirectly with other species. Studies on keystone species will contribute to the understanding of community stability and mechanisms underlying ecosystem degradation. Based on a survey in Haizhou Bay and adjacent waters in 2011, the food web was constructed according to the predator–prey relationships of species. The binary network was analysed to calculate 11 network indices to identify keystone species, and removal analysis was conducted to examine the effects of the extinction of keystone species on the food web. Kendall rank correlation analysis showed that there were significant correlations between most pairs of the 11 network indices (P<0.05). According to the results of principal component analysis of all these indices, several species, namely Leptochela gracilis, Loligo sp., Larimichthys polyactis, Alpheus japonicus and Oratosquilla oratoria, were identified as keystone species in the Haizhou Bay food web. Removal analysis suggested that the absence of keystone species may have considerable effects on the complexity and stability of the food web in Haizhou Bay. It is suggested that priority is given to the protection of keystone species in the marine ecosystem.
Correlations between social dominance orientation and political attitudes reflect common genetic underpinnings
Authors: Kleppestø Thomas Haarklau , Czajkowski Nikolai Olavi , Vassend Olav , Røysamb Espen , Eftedal Nikolai Haahjem , Sheehy-Skeffington Jennifer , Kunst Jonas R. , Thomsen Lotte
Published: August 2019

Significance

Deciphering the underlying psychology of societal attitudes and prejudices is important in times of political unpredictability. We focus on the foundational construct of preference for (or against) hierarchies between groups, as reflected in the 2 subdimensions of social dominance orientation (SDO). Studying SDO with a large-sample twin design, we show that both its sub-dimensions are heritable, share common genetic influences, and overlap genetically with 6 political attitudes that serve to enhance versus attenuate societal hierarchy. This suggests that desire for versus opposition to intergroup hierarchy, in abstract and concrete forms, constitutes a genetically-grounded behavioral syndrome, thus explaining an important part of the long-observed association among political views of various kinds.
A primarily serial, foveal accumulator underlies approximate numerical estimation
Authors: Cheyette Samuel J. , Piantadosi Steven T.
Published: August 2019

The approximate number system (ANS) has attracted broad interest due to its potential importance in early mathematical development and the fact that it is conserved across species. Models of the ANS and behavioral measures of ANS acuity both assume that quantity estimation is computed rapidly and in parallel across an entire view of the visual scene. We present evidence instead that ANS estimates are largely the product of a serial accumulation mechanism operating across visual fixations. We used an eye-tracker to collect data on participants’ visual fixations while they performed quantity-estimation and -discrimination tasks. We were able to predict participants’ numerical estimates using their visual fixation data: As the number of dots fixated increased, mean estimates also increased, and estimation error decreased. A detailed model-based analysis shows that fixated dots contribute twice as much as peripheral dots to estimated quantities; people do not “double count” multiply fixated dots; and they do not adjust for the proportion of area in the scene that they have fixated. The accumulation mechanism we propose explains reported effects of display time on estimation and earlier findings of a bias to underestimate quantities.
Interaction specificity of clustered protocadherins inferred from sequence covariation and structural analysis
Authors: Nicoludis John M. , Green Anna G. , Walujkar Sanket , May Elizabeth J. , Sotomayor Marcos , Marks Debora S. , Gaudet Rachelle
Published: August 2019

Clustered protocadherins, a large family of paralogous proteins that play important roles in neuronal development, provide an important case study of interaction specificity in a large eukaryotic protein family. A mammalian genome has more than 50 clustered protocadherin isoforms, which have remarkable homophilic specificity for interactions between cellular surfaces. A large antiparallel dimer interface formed by the first 4 extracellular cadherin (EC) domains controls this interaction. To understand how specificity is achieved between the numerous paralogs, we used a combination of structural and computational approaches. Molecular dynamics simulations revealed that individual EC interactions are weak and undergo binding and unbinding events, but together they form a stable complex through polyvalency. Strongly evolutionarily coupled residue pairs interacted more frequently in our simulations, suggesting that sequence coevolution can inform the frequency of interaction and biochemical nature of a residue interaction. With these simulations and sequence coevolution, we generated a statistical model of interaction energy for the clustered protocadherin family that measures the contributions of all amino acid pairs at the interface. Our interaction energy model assesses specificity for all possible pairs of isoforms, recapitulating known pairings and predicting the effects of experimental changes in isoform specificity that are consistent with literature results. Our results show that sequence coevolution can be used to understand specificity determinants in a protein family and prioritize interface amino acid substitutions to reprogram specific protein–protein interactions.
AP3M harbors actin filament binding activity that is crucial for vacuole morphology and stomatal closure in
Arabidopsis
Authors: Zheng Wenna , Jiang Yuxiang , Wang Xiangfeng , Huang Shanjin , Yuan Ming , Guo Yan
Published: August 2019

Significance

Actin filament dynamics and the proper functioning of adaptor complexes are required for the sorting of cargo proteins from the Golgi to the vacuole, but the relationship between these 2 important processes remains unclear. We show that AP3M, the medium (μ) subunit of the AP3 complex, directly binds to actin filaments at a conserved domain and severs the actin filaments in vitro. In addition, we show that the F-actin binding activity of AP3M is important for the cargo sorting mediated by the AP3 complex and for proper vacuole morphology. We propose that the proper functioning of AP3M in regulating F-actin dynamics is important for stomatal closure in
Arabidopsis thaliana
.
Power-law tail in lag time distribution underlies bacterial persistence
Authors: Şimşek Emrah , Kim Minsu
Published: August 2019

Significance

Persisters are antibiotic-tolerant cells that can evade antibiotic killing by maintaining long lag phase. They complicate antibiotic treatment, leading to treatment failure. Extensive studies in the field found that a myriad of molecular mechanisms leads to persisters. However, we still do not quantitatively understand, nor can we predict, the population dynamics of persistence, e.g., how the number of persisters changes over time. To address this issue, we characterized the lag time distribution of persisters. We observed a power-law decay in the tail of the distribution. We showed that this feature can quantitatively account for the population dynamics of persistence without ad hoc parameters. Additionally, we showed how this simple quantitative feature can emerge due to complicated molecular mechanisms.
Identification of a uranium–rhodium triple bond in a heterometallic cluster
Authors: Feng Genfeng , Zhang Mingxing , Wang Penglong , Wang Shuao , Maron Laurent , Zhu Congqing
Published: August 2019

Significance

Multimetallic species exhibit great potential in catalysis and small-molecule activation due to their multimetallic synergistic effects. Biological nitrogen fixation and industrial Haber–Bosch processes for ammonia synthesis are thought to involve multimetallic catalytic sites. Uranium-based materials were used as effective catalysts for ammonia production from nitrogen before an iron-based catalyst was used for the current industrial Haber–Bosch process. However, the synthesis and characterization of multimetallic species with uranium–metal bonds are significantly more challenging and no complex with
f
-block metal–metal triple bonds have been structurally authenticated by X-ray crystallography thus far. Here we report the identification of a
d
-
f
heterometallic cluster with 2 uranium–rhodium triple bonds.
Parkinson’s disease is a type of amyloidosis featuring accumulation of amyloid fibrils of α-synuclein
Authors: Araki Katsuya , Yagi Naoto , Aoyama Koki , Choong Chi-Jing , Hayakawa Hideki , Fujimura Harutoshi , Nagai Yoshitaka , Goto Yuji , Mochizuki Hideki
Published: August 2019

Significance

Lewy bodies (LBs), which mainly consist of α-syn, are neuropathological hallmarks of patients with Parkinson’s disease (PD). Recently, it has been reported that aggregates of α-syn with cross-β structures are capable of propagating within the brain in a prionlike manner. However, there is still no evidence that such propagation occurs in the patient’s brain. Here, we examined LBs in thin sections of autopsy brains of patients with PD using microbeam X-ray diffraction (XRD) and confirmed that aggregates of α-syn with a cross-β structure exist in brains of PD patients. Our finding supports the concept that PD is a type of amyloidosis, a disease featuring the accumulation and propagation of amyloid fibrils of α-syn.
Divergent allocation of sperm and the seminal proteome along a competition gradient inDrosophila melanogaster
Authors: Hopkins Ben R. , Sepil Irem , Thézénas Marie-Laëtitia , Craig James F. , Miller Thomas , Charles Philip D. , Fischer Roman , Kessler Benedikt M. , Bretman Amanda , Pizzari Tommaso , Wigby Stuart
Published: August 2019

Sperm competition favors large, costly ejaculates, and theory predicts the evolution of allocation strategies that enable males to plastically tailor ejaculate expenditure to sperm competition threat. While greater sperm transfer in response to a perceived increase in the risk of sperm competition is well-supported, we have a poor understanding of whether males (i) respond to changes in perceived intensity of sperm competition, (ii) use the same allocation rules for sperm and seminal fluid, and (iii) experience changes in current and future reproductive performance as a result of ejaculate compositional changes. Combining quantitative proteomics with fluorescent sperm labeling, we show thatDrosophila melanogastermales exercise independent control over the transfer of sperm and seminal fluid proteins (SFPs) under different levels of male–male competition. While sperm transfer peaks at low competition, consistent with some theoretical predictions based on sperm competition intensity, the abundance of transferred SFPs generally increases at high competition levels. However, we find that clusters of SFPs vary in the directionality and sensitivity of their response to competition, promoting compositional change in seminal fluid. By tracking the degree of decline in male mating probability and offspring production across successive matings, we provide evidence that ejaculate compositional change represents an adaptive response to current sperm competition, but one that comes at a cost to future mating performance. Our work reveals a previously unknown divergence in ejaculate component allocation rules, exposes downstream costs of elevated ejaculate investment, and ultimately suggests a central role for ejaculate compositional plasticity in sexual selection.
TheDrosophilaTrpm channel mediates calcium influx during egg activation
Authors: Hu Qinan , Wolfner Mariana F.
Published: August 2019

Significance

A rise in intracellular free calcium is a conserved feature of the egg-to-embryo transition in almost all animals. InDrosophila, as in vertebrates, the rise starts at one end of the oocyte and then travels across the egg in a wave. TheDrosophilacalcium rise is mediated by an influx of calcium due to the action of mechanically gated ion channels. Here, we identify the ion channel that is critical for the calcium entry as Trpm. Trpm is the ortholog of a channel recently shown to mediate the postfertilization calcium influxes needed to sustain calcium oscillations in fertilized mouse eggs, suggesting a deep homology despite species differences in the trigger for egg activation.
Plants obey (and disobey) the island rule
Authors: Biddick M. , Hendriks A. , Burns K. C.
Published: August 2019

The island rule predicts that small animals evolve to become larger on islands, while large animals evolve to become smaller. It has been studied for over half a century, and its validity is fiercely debated. Here, we provide a perspective on the debate by conducting a test of the island rule in plants. Results from an extensive dataset on islands in the southwest Pacific illustrate that plant stature and leaf area obey the island rule, but seed size does not. Our results indicate that the island rule may be more pervasive than previously thought and that support for its predictions varies among functional traits.
Inhibitory interneurons mediate autism-associated behaviors via 4E-BP2
Authors: Wiebe Shane , Nagpal Anmol , Truong Vinh T. , Park Jeehyun , Skalecka Agnieszka , He Alexander J. , Gamache Karine , Khoutorsky Arkady , Gantois Ilse , Sonenberg Nahum
Published: August 2019

Significance

Disrupting cellular mechanisms that control protein synthesis can lead to autism spectrum disorder (ASD) in humans. Repetitive motions, impaired social interaction, and altered vocal communication are core symptoms of ASD and can be mimicked in mice. Deletion of the protein synthesis inhibitor, eukaryotic initiation factor 4E binding protein 2 (4E-BP2), causes autistic behaviors in mice. Using a variety of conditional knockout mouse models, we found that loss of 4E-BP2 in inhibitory neurons in the brain, but not in excitatory neurons or astrocytes, causes autistic behaviors.
Recognition with metallo cavitands
Authors: Rahman Faiz-Ur , Li Yong-sheng , Petsalakis Ioannis D. , Theodorakopoulos Giannoula , Rebek Julius , Yu Yang
Published: August 2019

Significance

Cavitands are nanoscale container molecules widely used in studies of molecular recognition and reactivity. They act as hosts that temporarily confine small molecule guests and much of their action as reaction chambers is due to movable walls allowing the uptake and release of guests. Water-soluble and organic-soluble cavitands featuring quinoxaline walls were prepared and their complexes with alkanes, and amphiphilic guests were characterized by
1
H NMR spectroscopy and computational methods. The quinoxalines bound Pd(II) near the rim of the cavitands and distorted the shape of the space, stabilized the receptive forms, and enhanced guest binding. Further development and application of cavitands as reaction vessels depends on closely positioned charges and potentially interactive sites near the cavity and its contents.
Disrupted mechanobiology links the molecular and cellular phenotypes in familial dilated cardiomyopathy
Authors: Clippinger Sarah R. , Cloonan Paige E. , Greenberg Lina , Ernst Melanie , Stump W. Tom , Greenberg Michael J.
Published: August 2019

Significance

One of the outstanding challenges in understanding familial dilated cardiomyopathy has been connecting mutation-induced changes in sarcomeric protein function with the phenotype seen in cells. Many of the mutation-induced changes in contractility at the molecular scale are subtle, begging the question of how they lead to a devastating progressive disease. Here, we show that disease-causing mutations in sarcomeric proteins affect not only contraction but also how cardiomyocytes sense and respond to changes in their mechanical environment associated with aging and the disease progression. Our results implicate impaired mechanosensing as an underappreciated mechanism in the pathogenesis and progression of dilated cardiomyopathy, and they have important implications for the design of precision therapeutics.
The representation of sex work in the Greek Press
Authors: Sagredos Christos
Published: August 2019

The representation of sex work in the media has received little to no attention in the field of linguistics and discourse analysis. Given that news discourse can have a huge impact on public opinions, ideologies and norms, and the setting of political agendas and policies (van Dijk 1989), the study adopts a Corpus-Assisted Critical Discourse Analysis (CACDA) approach (Baker, Gabrielatos, KhosraviNik, Krzyżanowski, McEnery & Wodak 2008), seeking to explore whether journalists reproduce or challenge negative stereotypes vis-à-vis sex work. Examining 82 articles published in three Greek newspapers (Kathimerini, TA NEA, Efimerida ton Syntakton) in 2017, this paper considers the lexico-grammatical choices that are typically involved in the representation of sex work and sex workers in the Press. Drawing on Systemic Functional Linguistics, the Discourse Historical Approach and corpus linguistics, the analysis links the textual findings (micro-level context) with the discourse practice context (meso-context) as well as the social context in which sex work occurs (macro-context). Findings illustrate that although sex work in Greece has been legalised for about two decades, traces of abolitionist discourses can be found in the Press, building barriers in the emancipatory efforts of sex workers who stand up for having equal civil and labour rights as their fellow citizens.
Communicating trans identity
Authors: Ryan J. Michael
Published: August 2019

This paper will analyze a series of qualitative interviews to better understand the selection and significance of gender identity-based terminology used by trans persons in the United Kingdom. An analysis of factors such as the perceived understanding of terminology available at a given historical moment (i.e. transgender, transman, trans, etc.), identity of interactors (i.e. trans or cis identified), and purpose of interaction (i.e. legal, medical) will be considered to better understand the terminology chosen by individuals to construct and communicate their gender identity in a way that has meaning both to themselves as well as to those with whom they are communicating. Analysis will help to develop a deeper understanding of the importance of terminology in how trans persons understand and communicate their gender identity.
A pragmatic analysis of the speech act of criticizing in university teacher-student talk
Authors: El-Dakhs Dina Abdel Salam , Ambreen Fatima , Zaheer Maria , Gusarova Yulia
Published: August 2019

The current study examined the realization of the speech act of criticizing by university teachers in their talk
with students. To this end, role-plays were conducted with 60 university teachers (30 males and 30 females) at a private Saudi
university which is characterized by its multicultural academic staff, and, hence, where English is used as a lingua franca.
Recordings were transcribed and analyzed using an adapted version of Nguyen’s (2005,
2013) model of criticism strategies. The results showed the teachers’ preference
for indirect over direct criticism strategies and their minimal use of modifiers, particularly internal ones. It was also found
that the influence of the teacher’s gender or years of teaching experience was small while the severity of the situation was a
critical factor in the choice of appropriate strategies. The results were interpreted in relation to the existing literature and
the theoretical model of politeness.
Comparing pathways for long-term heart rate modulation by the funny current
Authors: DiFrancesco Dario
Published: August 2019

Heart rate control by the funny current (If) involves both fast, cAMP-dependent, and slow, membrane expression–based mechanisms to adapt to different needs.
Topological bands and localized vibration modes in quasiperiodic beams
Authors: Pal Raj Kumar , Rosa Matheus I N , Ruzzene Massimo
Published: August 2019

We investigate a family of quasiperiodic continuous elastic beams, the topological properties of their vibrational spectra, and their relation to the existence of localized modes. We specifically consider beams featuring arrays of ground springs at locations determined by projecting from a circle onto an underlying periodic system. A family of periodic and quasiperiodic structures is obtained by smoothly varying a parameter defining such projection. Numerical simulations show the existence of vibration modes that first localize at a boundary, and then migrate into the bulk as the projection parameter is varied. Explicit expressions predicting the change in the density of states of the bulk define topological invariants that quantify the number of modes spanning a gap of a finite structure. We further demonstrate how modulating the phase of the ground springs distribution causes the topological states to undergo an edge-to-edge transition. The considered configurations and topological studies provide a framework for inducing localized modes in continuous elastic structural components through globally spanning, deterministic perturbations of periodic patterns defined by the considered projection operations.
Novel theoretical constraints for color-octet scalar models *
Authors: Cheng Li , Eberhardt Otto , Murphy Christopher W.
Published: August 2019

We study the theoretical constraints on a model whose scalar sector contains one color octet and one or two color singlet SU(2)
L
doublets. To ensure unitarity of the theory, we constrain the parameters of the scalar potential for the first time at the next-to-leading order in perturbation theory. Moreover, we derive new conditions guaranteeing the stability of the potential. We employ the HEPfit package to extract viable parameter regions at the electroweak scale and test the stability of the renormalization group evolution up to the multi-TeV region. Furthermore, we set upper limits on the scalar mass splittings. All results are given for both cases with and without a second scalar color singlet.
Anisotropic evolution of 4-brane in a 6D generalized Randall-Sundrum model *
Authors: Kang Guang-Zhen , Zhang De-Sheng , Du Long , Xu Jun , Zong Hong-Shi
Published: August 2019

We investigate a 6D generalized Randall-Sundrum brane world scenario with a bulk cosmological constant. Each stress-energy tensor

on the brane is shown to be similar to a constant vacuum energy. This is consistent with the Randall-Sundrum model, in which each 3-brane Lagrangian yielded a constant vacuum energy. By adopting an anisotropic metric ansatz, we obtain the 5D Friedmann-Robertson-Walker field equations. In a slightly later period, the expansion of the universe is proportional to the square root of time,

, which is similar to the period of the radiation-dominated regime. Moreover, we investigate the case with two

and two

. In a large range of

, we obtain the 3D effective cosmological constant

, which is independent of the integral constant. Here, the scale factor is an exponential expansion, which is consistent with our present observation of the universe. Our results demonstrate that it is possible to construct a model that solves the dark energy problem, while guaranteeing a positive brane tension.
Computing graded Betti tables of toric surfaces
Authors: Castryck Wouter , Cools Filip , Demeyer Jeroen , Lemmens Alexander
Published: August 2019

We present various facts on the graded Betti table of a projectively embedded toric surface, expressed in terms of the combinatorics of its defining lattice polygon. These facts include explicit formulas for a number of entries, as well as a lower bound on the length of the quadratic strand that we conjecture to be sharp (and prove to be so in several special cases). We also present an algorithm for determining the graded Betti table of a given toric surface by explicitly computing its Koszul cohomology and report on an implementation in SageMath. It works well for ambient projective spaces of dimension up to roughly

25
25

, depending on the concrete combinatorics, although the current implementation runs in finite characteristic only. As a main application we obtain the graded Betti table of the Veronese surface

ν
6

(

P

2

)
⊆

P

27

\nu _6(\mathbb {P}^2) \subseteq \mathbb {P}^{27}

in characteristic

40

009

40\,009

. This allows us to formulate precise conjectures predicting what certain entries look like in the case of an arbitrary Veronese surface

ν
d

(

P

2

)

\nu _d(\mathbb {P}^2)

.