bluuebunny/crossref_metadata_2025 huggingface dataset:
In depth characterization of Ge-Si core-shell nanowires using X-ray coherent diffraction and time resolved pump-probe spectroscopy
Authors: Fernández Sara , Jean Cyril , Charron Eric , Gentile Pascal , Richard Marie-Ingrid , Thomas Olivier , Perrin Bernard , Belliard Laurent
Published: November 2019

We report on the ultrafast vibrational response of single Ge-Si core-shell nanowires obtained by epitaxial growth and investigated by femtosecond transient reflectivity and coherent x-ray diffraction measurements. The oscillations of the sample reflectivity are correlated with the fundamental breathing mode for wires with a diameter ranging from 150 to 350 nm and compared with solutions of the Navier equation. Taking advantage of a free standing geometry, we are able to get a mechanical quality factor of higher than 80. Coupling electron microscopy and pump and probe investigations with a very high spectral resolution performed on the same wire, we demonstrate that both shell and core diameter fluctuations are revealed and quantified. X-ray coherent diffraction measurements on individual nanowires evidence changes in the Ge-core diameter and different strain states along a single structure.
Transition to chaos in a cross-corrugated channel at low Reynolds numbers
Authors: Zhu Xiaowei , Walther Jens Honore , Zhao Dan , Haglind Fredrik
Published: November 2019

The pressure-gradient driven flow in a three-dimensional cross-corrugated channel is investigated based on large eddy simulations. The channel geometry is highly tortuous so that the flow unsteadiness can be triggered at a moderate Reynolds number. The objective of this paper is to provide a better understanding of the laminar-to-chaotic transition in this type of channel. The transition from steady to chaos is found to occur at a low Reynolds number range between 77.4 and 113.1. The nonlinear dynamics is analyzed based on the power spectra of the velocity and reconstructed phase space. The route to chaos is identified, which favors the Ruelle-Takens-Newhouse scenario. Moreover, the transition from quasiperiodic mode to chaotic mode is accompanied with temporal intermittencies. The fluid dynamics is analyzed. It is found that the cross-corrugated geometry prompts a recirculating-and-rotating wake behind each contact corner. Each wake is enfolded by a pair of curved free shear layers. They are destabilized by the Kelvin-Helmholtz instability, leading to the periodic flow oscillation. Subsequently, the centrifugal instability sets in and promotes a type of primary vortex structures, forming streamwise “zig-zag” vortex streets. The competition between the adjacent vortex streets leads to a quasiperiodic flow. Temporal intermittencies emerge as the Reynolds number is increased. Finally, the periodicities in both the streamwise and spanwise directions are broken, and the flow becomes chaotic. When further increasing the Reynolds number to 343.1, Taylor-Görtler-like vortexes and necklace-like vortexes are formed in the channel.
On the quantum mechanics of how an ideal carbon nanotube field emitter can exhibit a constant field enhancement factor
Authors: de Castro Caio P. , de Assis Thiago A. , Rivelino Roberto , B. Mota Fernando de , de Castilho Caio M. C. , Forbes Richard G.
Published: November 2019

Measurements of current-voltage characteristics from ideal carbon nanotube (CNT) field electron emitters of a small apex radius have shown that these emitters can exhibit a linear Fowler-Nordheim plot [e.g., Dean and Chalamala, Appl. Phys. Lett. 76, 375 (2000)]. From such a plot, a constant (voltage-independent) characteristic field enhancement factor (FEF) can be deduced. Over 15 years later, this experimental result has not yet been convincingly retrieved from first-principles electronic-structure calculations or, more generally, from quantum mechanics (QMs). On the contrary, several QM calculations have deduced that the characteristic FEF should be a function of the macroscopic field applied to the CNT. This apparent contradiction between the experiment and the QM theory has been an unexplained feature of CNT emission science and has raised doubts about the ability of existing QM models to satisfactorily describe experimental CNT emission behavior. In this work, we demonstrate, by means of a density functional theory analysis of single-walled CNTs “floating” in an applied macroscopic field, the following significant result. This is that the agreement between the experiment, classical-conductor CNT models, and QM calculations can be achieved if the latter are used to calculate (from the “real” total-charge-density distributions initially obtained) the distributions of “induced” charge-density, induced local fields, and induced local FEFs. A similar result was previously obtained for so-called vertically aligned CNT/graphene structures. The present work confirms, more reliably and in significantly greater detail than in earlier work on a different system, that this finding applies to the common “post-on-a-conducting plane” situation of CNT field electron emission. This finding also brings out various further theoretical questions that need to be explored.
Convergence rate in homogenization of elliptic systems with singular perturbations
Authors: Niu Weisheng , Yuan Yue
Published: November 2019

We consider the optimal convergence rate in periodic homogenization of second order elliptic systems involving singular perturbations in bounded domains. By introducing proper auxiliary functions, we establish the sharp convergence rate in L2(Ω) by using the duality argument.
A general time-domain formulation of equation-of-motion coupled-cluster theory for linear spectroscopy
Authors: Nascimento Daniel R. , DePrince A. Eugene
Published: November 2019

A time-dependent (TD) formulation of equation-of-motion (EOM) coupled-cluster (CC) theory is developed, which, unlike other similar TD-EOM-CC approaches [D. R. Nascimento and A. E. DePrince III, J. Chem. Theory Comput. 12, 5834–5840 (2016)], can be applied to any type of linear electronic spectroscopy. The TD-EOM-CC method is formally equivalent to the standard frequency-domain formulation of EOM-CC theory, with a potential computational advantage of a comparatively low memory footprint. This general TD-EOM-CC framework is applied to the linear absorption and electric circular dichroism spectra of several small oxirane derivatives.
Directly extracting the authentic basis of cylindrical vector beams by a pump-probe technique in an atomic vapor
Authors: Wang Jinwen , Yang Xin , Dou Zhenghui , Qiu Shuwei , Liu Jun , Chen Yun , Cao Mingtao , Chen Haixia , Wei Dong , Müller-Dethlefs Klaus , Gao Hong , Li Fuli
Published: November 2019

The projective measurement of light polarization is usually employed by using a combination of a quarter-waveplate, half-waveplate, and polarizing beam splitter. This configuration is also widely used for exploring quantum states. However, this kind of measurement destroys the real polarization state of the target. Here, an effective measurement configuration to extract the “authentic basis” of cylindrical vector beams with arbitrary polarization distribution in an atomic vapor is presented. An intense pump beam induces a distribution of atoms at different Zeeman sublevels, which allows for the extraction of the special polarization state of a counter propagated weak probe beam. The extracted part still maintains the original polarization and the vortex phase. Different orders of cylindrical vector beams are tested in this configuration, and the authentic basis of cylindrical vector beams is extracted as predicted. This work has potential applications in atomic physics and polarization optics. Furthermore, it provides a reference for the quantum projective measurement based on atom-optical devices.
Charge transfer and spillover phenomena in ceria-supported iridium catalysts: A model study
Authors: Lykhach Yaroslava , Kubát Jan , Neitzel Armin , Tsud Nataliya , Vorokhta Mykhailo , Skála Tomáš , Dvořák Filip , Kosto Yuliia , Prince Kevin C. , Matolín Vladimír , Johánek Viktor , Mysliveček Josef , Libuda Jörg
Published: November 2019

Iridium-based materials are among the most active bifunctional catalysts in heterogeneous catalysis and electrocatalysis. We have investigated the properties of atomically defined Ir/CeO2(111) model systems supported on Cu(111) and Ru(0001) by means of synchrotron radiation photoelectron spectroscopy, resonant photoemission spectroscopy, near ambient pressure X-ray photoelectron spectroscopy (NAP XPS), scanning tunneling microscopy, and temperature programmed desorption. Electronic metal-support interactions in the Ir/CeO2(111) system are accompanied by charge transfer and partial reduction of CeO2(111). The magnitude of the charge transfer depends strongly on the Ir coverage. The Ir/CeO2(111) system is stable against sintering upon annealing to 600 K in ultrahigh vacuum (UHV). Annealing of Ir/CeO2(111) in UHV triggers the reverse oxygen spillover above 450 K. The interaction of hydrogen with Ir/CeO2(111) involves hydrogen spillover and reversible spillover between 100 and 400 K accompanied by the formation of water above 190 K. Formation of water coupled with the strong reduction of CeO2(111) represents the dominant reaction channel upon annealing in H2 above 450 K. The interaction of Ir/CeO2(111) with oxygen has been investigated at moderate and NAP conditions. Additionally, the formation and stability of iridium oxide prepared by deposition of Ir in oxygen atmosphere was investigated upon annealing in UHV and under exposure to H2. The oxidation of Ir nanoparticles under NAP conditions yields stable IrOx nanoparticles. The stability of Ir and IrOx nanoparticles under oxidizing conditions is hampered, however, by encapsulation by cerium oxide above 450 K and additionally by copper and ruthenium oxides under NAP conditions.
Effects of the flapping frequency on the thrust performance for three-dimensional bionic multi-wings in a schooling
Authors: Zhang Yang , Han Jiakun , Chen Gang
Published: November 2019

The excellent performance of many creatures using flapping wings has attracted a lot of research on the performance of a single flapping wing. However, many species generally choose highly organized movements rather than alone in the animal world; there is a very popular and interesting biological clustering phenomenon known as schooling. Understanding the flow mechanisms and thrust performance of flapping multiwings in a schooling could be applied to novel bionic flapping wing aircraft formation design. We perform numerical simulations employing the immersed boundary-lattice Boltzmann method for flow over a single flapping wing and the flapping multiwings in a diamond schooling at different St numbers. Meanwhile, the effects of the difference in individual flapping frequency on the overall propulsive performance of the schooling were investigated. We present the spectra of aerodynamic forces for a single flapping wing and each wing in a diamond schooling at different individual flapping frequencies. Numerical results indicate that the flapping frequency has great effects on the thrust performance of a single wing and the multiwings in a schooling. The average thrust coefficient of a single flapping wing grows with the increase in the St. However, there is an optimal St number to obtain the maximum propulsive efficiency. For a schooling that maintains the same flapping frequency, the overall schooling or each wing in a schooling shows the same trend as a single wing. For a schooling with different individual flapping frequencies, the aerodynamic characteristics of the last downstream wing are more affected by the frequency difference.
Gamma-ray radiation effects in graphene-based transistors with h-BN nanometer film substrates
Authors: Cazalas E. , Hogsed M. R. , Vangala S. , Snure M. R. , McClory J. W.
Published: November 2019

Radiation effects on graphene field effect transistors (GFETs) with hexagonal boron nitride (h-BN) thin film substrates are investigated using 60Co gamma-ray radiation. This study examines the radiation response using many samples with varying h-BN film thicknesses (1.6 and 20 nm thickness) and graphene channel lengths (5 and 10 μm). These samples were exposed to a total ionizing dose of approximately 1 Mrad(Si). I-V measurements were taken at fixed time intervals between irradiations and postirradiation. Dirac point voltage and current are extracted from the I-V measurements, as well as mobility, Dirac voltage hysteresis, and the total number of GFETs that remain properly operational. The results show a decrease in Dirac voltage during irradiation, with a rise of this voltage and permanent drop in Dirac current postirradiation. 1.6 nm h-BN substrate GFETs show an increase in mobility during irradiation, which drops back to preirradiation conditions in postirradiation measurements. Hysteretic changes to the Dirac voltage are the strongest during irradiation for the 20 nm thick h-BN substrate GFETs and after irradiation for the 1.6 nm thick h-BN GFETs. Failure rates were similar for most GFET types during irradiation; however, after irradiation, GFETs with 20 nm h-BN substrates experienced substantially more failures compared to 1.6 nm h-BN substrate GFETs.
Variable viscosity effects for the steady flow past a sphere
Authors: Housiadas Kostas D. , Beris Antony N.
Published: November 2019

The effect of a spatially dependent viscosity in the unbounded flow around a rigid spherical particle that translates with constant velocity is investigated theoretically. The variable viscosity emulates the effect of a variable concentration of an additive material in a simple solvent. The analysis is performed utilizing a smooth function for the viscosity of the additive material, which can describe qualitatively both depletion and accumulation phenomena around the particle. Assuming steady state, creeping and isothermal conditions, and no external forces and torques, the momentum and mass balances are a generalization of the classical Stokes equations for which the linearity is preserved. Manipulating suitably the governing partial differential equations, a single ordinary integrodifferential equation for the radial part of the radial velocity component is derived. This equation is solved either numerically using a Chebyshev pseudospectral method or analytically using an asymptotic technique. A decrease in the total drag on the particle as the additive material increases is predicted in the depletion case. In the accumulation case, the total drag may increase or decrease in comparison to the simple Newtonian fluid. Analysis of the total drag to its individual contributions reveals that the friction drag (due to viscous forces) is affected substantially by the change of the viscosity, while the form drag (due to pressure) varies much smoother and milder. Finally, we investigate under which conditions the variable viscosity fluid can be approximated as a constant viscosity fluid with Navier type slip at the wall.
Observation of anomalous Ettingshausen effect and large transverse thermoelectric conductivity in permanent magnets
Authors: Miura Asuka , Sepehri-Amin Hossein , Masuda Keisuke , Tsuchiura Hiroki , Miura Yoshio , Iguchi Ryo , Sakuraba Yuya , Shiomi Junichiro , Hono Kazuhiro , Uchida Ken-ichi
Published: November 2019

This study focuses on the potential of permanent magnets as thermoelectric converters. It is found that a SmCo5-type magnet exhibits a large anomalous Ettingshausen effect (AEE) at room temperature and that its charge-to-heat current conversion coefficient is more than one order of magnitude greater than that of typical ferromagnetic metals. The large AEE is an exclusive feature of the SmCo5-type magnet among various permanent magnets in practical use, which is independent of the conventional performance of magnets based on static magnetic properties. The experimental results show that the large AEE originates from the intrinsic transverse thermoelectric conductivity of SmCo5. This finding makes a connection between permanent magnets and thermal energy engineering, providing the basis for creating “thermoelectric permanent magnets.”
Safeguarding injured Victorians: development and implementation of an evidence-informed system to manage therapeutic uncertainty and decision making in a compensable environment
Authors: Sherry Lisa J. , Briggs Andrew M. , Pizzari Tania
Published: November 2019

WorkSafe Victoria and the Transport Accident Commission are two Victorian government agencies that determine the policies that guide decisions to fund treatments and services provided to Victorians injured in transport or workplace accidents. These agencies identified that an internal system was required to manage requests for funding of new or emerging treatments. In particular, the agencies recognised a system that supported consistency in decision making in the context of therapeutic uncertainty and ensured the safety of injured Victorians was needed. The New, Emerging or Non-Established Treatments (NENETs) policy was launched in its current form by the agencies in 2013. The NENETs system includes a record of contemporary evidence for emerging treatments and an evidence-informed decision-making system to ensure consistency and information sharing. A system of recording decisions on emerging treatments was also implemented to ensure that funding decisions could later be reversed if necessary. The NENETs system has proved to be a robust and sustainable method of managing uncertainty for WorkSafe Victoria and the Transport Accident Commission and could be transferable to other funding bodies.
What is known about the topic?An algorithm to guide clinicians when prescribing off-label medications was developed in 2006, although it has not been used widely in everyday practice. In 2019 the Medical Board of Australia launched a discussion paper on ‘complementary and unconventional medicine and emerging treatments’ because no system for managing such treatments exists. Third-party payers have a responsibility to make objective and reliable decisions about new, emerging or non-established treatments to ensure high value care is offered to health consumers.
What does this paper add?This paper provides an overview of the policy and decision-making system implemented by WorkSafe Victoria and the Transport Accident Commission to managing requests for new, emerging or non-established treatments. The system is adaptable to other third-party payers, health service funders and regulators in Australia and internationally.
What are the implications for practitioners?It is important that practitioners caring for injured Victorians are aware of the systems used to inform decision making around requests for funding new, emerging or non-established treatments. Knowledge of the principles underlying this system may assist other funding bodies and the Medical Board of Australia to develop systems in other jurisdictions.
Contemporary Aboriginal savanna burning projects in Arnhem Land: a regional description and analysis of the fire management aspirations of Traditional Owners
Authors: Ansell Jennifer , Evans Jay , Adjumarllarl Rangers  , Arafura Swamp Rangers  , Djelk Rangers  , Jawoyn Rangers  , Mimal Rangers  , Numbulwar Numburindi Rangers  , Warddeken Rangers  , Yirralka Rangers  , Yugul Mangi Rangers
Published: November 2019

The growth of the carbon industry in Australia over the last decade has seen an increase in the number of eligible offsets projects utilising the savanna burning methods in northern Australia. Many of these projects are operated by Aboriginal people on Aboriginal lands utilising local Aboriginal knowledge and customary burning practice. The present paper reviews existing land management planning documents to describe the aspirations of Traditional Owners in relation to fire management at a regional scale in Arnhem Land. Available data collected in the course of savanna burning operations are then utilised to examine the extent to which the savanna burning projects are meeting these goals. There were six clear goals in relation to fire management within the planning documents across Arnhem Land. Traditional Owners want to: (1) continue the healthy fire management of their country; (2) see fewer wildfires; (3) protect biodiversity; (4) protect culturally important sites; (5) maintain and transfer knowledge; and (6) create a carbon abatement. The results from this paper suggest that although the savanna burning projects are annually variable, these goals are being met. Importantly, the present paper clearly communicates a description of contemporary fire management from the perspective of Traditional Owners at a broad regional scale.
Technoeconomic and life-cycle analysis of single-step catalytic conversion of wet ethanol into fungible fuel blendstocks
Authors: Hannon John R. , Lynd Lee R. , Andrade Onofre , Benavides Pahola Thathiana , Beckham Gregg T. , Biddy Mary J. , Brown Nathan , Chagas Mateus F. , Davison Brian H. , Foust Thomas , Junqueira Tassia L. , Laser Mark S. , Li Zhenglong , Richard Tom , Tao Ling , Tuskan Gerald A. , Wang Michael , Woods Jeremy , Wyman Charles E.
Published: November 2019

Technoeconomic and life-cycle analyses are presented for catalytic conversion of ethanol to fungible hydrocarbon fuel blendstocks, informed by advances in catalyst and process development. Whereas prior work toward this end focused on 3-step processes featuring dehydration, oligomerization, and hydrogenation, the consolidated alcohol dehydration and oligomerization (CADO) approach described here results in 1-step conversion of wet ethanol vapor (40 wt% in water) to hydrocarbons and water over a metal-modified zeolite catalyst. A development project increased liquid hydrocarbon yields from 36% of theoretical to >80%, reduced catalyst cost by an order of magnitude, scaled up the process by 300-fold, and reduced projected costs of ethanol conversion 12-fold. Current CADO products conform most closely to gasoline blendstocks, but can be blended with jet fuel at low levels today, and could potentially be blended at higher levels in the future. Operating plus annualized capital costs for conversion of wet ethanol to fungible blendstocks are estimated at $2.00/GJ for CADO today and $1.44/GJ in the future, similar to the unit energy cost of producing anhydrous ethanol from wet ethanol ($1.46/GJ). Including the cost of ethanol from either corn or future cellulosic biomass but not production incentives, projected minimum selling prices for fungible blendstocks produced via CADO are competitive with conventional jet fuel when oil is $100 per barrel but not at $60 per barrel. However, with existing production incentives, the projected minimum blendstock selling price is competitive with oil at $60 per barrel. Life-cycle greenhouse gas emission reductions for CADO-derived hydrocarbon blendstocks closely follow those for the ethanol feedstock.
Fundamentally different global marine nitrogen cycling in response to severe ocean deoxygenation
Authors: Naafs B. David A. , Monteiro Fanny M. , Pearson Ann , Higgins Meytal B. , Pancost Richard D. , Ridgwell Andy
Published: November 2019

The present-day marine nitrogen (N) cycle is strongly regulated by biology. Deficiencies in the availability of fixed and readily bioavailable nitrogen relative to phosphate (P) in the surface ocean are largely corrected by the activity of diazotrophs. This feedback system, termed the “nitrostat,” is thought to have provided close regulation of fixed-N speciation and inventory relative to P since the Proterozoic. In contrast, during intervals of intense deoxygenation such as Cretaceous ocean anoxic event (OAE) 2, a few regional sedimentary δ
15
N records hint at the existence of a different mode of marine N cycling in which ammonium plays a major role in regulating export production. However, the global-scale dynamics during this time remain unknown. Here, using an Earth System model and taking the example of OAE 2, we provide insights into the global marine nitrogen cycle under severe ocean deoxygenation. Specifically, we find that the ocean can exhibit fundamental transitions in the species of nitrogen dominating the fixed-N inventory––from nitrate (NO
3
−
) to ammonium (NH
4
+
)––and that as this transition occurs, the inventory can partially collapse relative to P due to progressive spatial decoupling between the loci of NH
4
+
oxidation, NO
3
−
reduction, and nitrogen fixation. This finding is relatively independent of the specific state of ocean circulation and is consistent with nitrogen isotope and redox proxy data. The substantive reduction in the ocean fixed-N inventory at an intermediate state of deoxygenation may represent a biogeochemical vulnerability with potential implications for past and future (warmer) oceans.
Assessing the Russian Internet Research Agency’s impact on the political attitudes and behaviors of American Twitter users in late 2017
Authors: Bail Christopher A. , Guay Brian , Maloney Emily , Combs Aidan , Hillygus D. Sunshine , Merhout Friedolin , Freelon Deen , Volfovsky Alexander
Published: November 2019

There is widespread concern that Russia and other countries have launched social-media campaigns designed to increase political divisions in the United States. Though a growing number of studies analyze the strategy of such campaigns, it is not yet known how these efforts shaped the political attitudes and behaviors of Americans. We study this question using longitudinal data that describe the attitudes and online behaviors of 1,239 Republican and Democratic Twitter users from late 2017 merged with nonpublic data about the Russian Internet Research Agency (IRA) from Twitter. Using Bayesian regression tree models, we find no evidence that interaction with IRA accounts substantially impacted 6 distinctive measures of political attitudes and behaviors over a 1-mo period. We also find that interaction with IRA accounts were most common among respondents with strong ideological homophily within their Twitter network, high interest in politics, and high frequency of Twitter usage. Together, these findings suggest that Russian trolls might have failed to sow discord because they mostly interacted with those who were already highly polarized. We conclude by discussing several important limitations of our study—especially our inability to determine whether IRA accounts influenced the 2016 presidential election—as well as its implications for future research on social media influence campaigns, political polarization, and computational social science.
DJ-1 regulates the integrity and function of ER-mitochondria association through interaction with IP3R3-Grp75-VDAC1
Authors: Liu Yi , Ma Xiaopin , Fujioka Hisashi , Liu Jun , Chen Shengdi , Zhu Xiongwei
Published: November 2019

Significance

Endoplasmic reticulum (ER) and mitochondria form close associations that serve as a critical signaling platform. Loss-of-function mutations in DJ-1 are associated with autosomal recessive early onset Parkinson’s disease (PD). We found that DJ-1 knockout caused significant impairments in the structure and function of ER-mitochondria association in neuronal cells and in vivo. Reduced DJ-1 was associated with deficits in ER-mitochondria association in the substantia nigra of sporadic PD. Our study identifies DJ-1 as a critical component of the macrocomplex containing IP3R3-Grp75-VDAC1 at mitochondria-associated membrane and as playing an important role in the regulation of the integrity and function of ER-mitochondria association. Our research offers insights into the regulation mechanism of ER-mitochondria association and the pathogenic mechanism of DJ-1 deficiency in PD.
Understanding, predicting, and tuning the fragility of vitrimeric polymers
Authors: Ciarella Simone , Biezemans Rutger A. , Janssen Liesbeth M. C.
Published: November 2019

Significance

The intricate interplay between the molecular structure of a material and its emergent macroscopic dynamics lies at the heart of modern materials science. This interplay, however, remains notoriously poorly understood for glass-forming systems. The recent advent of vitrimers—a promising new class of recyclable high-performance polymers with anomalous glass-forming properties—revives the urgency to gain a full understanding of the elusive structure–dynamics link in glassy matter. We combine computer simulations and first-principles theory to rationally expose the structural origins of the complex glassy dynamics in vitrimers. Our findings provide cues for a better fundamental understanding of glass formation and may stimulate the development of sustainable amorphous materials with on-demand functionalities.
Palmitoylation of BMPR1a regulates neural stem cell fate
Authors: Wegleiter Thomas , Buthey Kilian , Gonzalez-Bohorquez Daniel , Hruzova Martina , bin Imtiaz Muhammad Khadeesh , Abegg Andrin , Mebert Iliana , Molteni Adriano , Kollegger Dominik , Pelczar Pawel , Jessberger Sebastian
Published: November 2019

Neural stem cells (NSCs) generate neurons and glial cells throughout embryonic and postnatal brain development. The role of S-palmitoylation (also referred to as S-acylation), a reversible posttranslational lipid modification of proteins, in regulating the fate and activity of NSCs remains largely unknown. We used an unbiased screening approach to identify proteins that are S-acylated in mouse NSCs and showed that bone morphogenic protein receptor 1a (BMPR1a), a core mediator of BMP signaling, is palmitoylated. Genetic manipulation of S-acylated sites affects the localization and trafficking of BMPR1a and leads to altered BMP signaling. Strikingly, defective palmitoylation of BMPR1a modulates NSC function within the mouse brain, resulting in enhanced oligodendrogenesis. Thus, we identified a mechanism regulating the behavior of NSCs and provided the framework to characterize dynamic posttranslational lipid modifications of proteins in the context of NSC biology.
Native habitat mitigates feast–famine conditions faced by honey bees in an agricultural landscape
Authors: Dolezal Adam G. , St. Clair Ashley L. , Zhang Ge , Toth Amy L. , O’Neal Matthew E.
Published: November 2019

Significance

Industrial-scale production of crops through monocultures has resulted in “green deserts” of reduced biodiversity in many areas worldwide. Such simplified landscapes may impact ecosystem services such as pollination. Here, we present a large-scale, longitudinal study of managed honey bee colonies in the context of corn and soybean monocultures. Our results reveal a brief burst of colony growth during soybean bloom, followed by a longer period of forage dearth, resulting in decline in several aspects of honey bee health at both colony and individual levels. We demonstrate this decline is reversible when honey bees have access to native, perennial plants (i.e., prairie). Our results suggest sustainable pollinator management in landscapes dominated by monocultures can be achieved through reintegration of native biodiversity.
The impact of rising CO2and acclimation on the response of US forests to global warming
Authors: Sperry John S. , Venturas Martin D. , Todd Henry N. , Trugman Anna T. , Anderegg William R. L. , Wang Yujie , Tai Xiaonan
Published: November 2019

The response of forests to climate change depends in part on whether the photosynthetic benefit from increased atmospheric CO2(∆Ca= future minus historic CO2) compensates for increased physiological stresses from higher temperature (∆T). We predicted the outcome of these competing responses by using optimization theory and a mechanistic model of tree water transport and photosynthesis. We simulated current and future productivity, stress, and mortality in mature monospecific stands with soil, species, and climate sampled from 20 continental US locations. We modeled stands with and without acclimation to ∆Caand ∆T, where acclimated forests adjusted leaf area, photosynthetic capacity, and stand density to maximize productivity while avoiding stress. Without acclimation, the ∆Ca-driven boost in net primary productivity (NPP) was compromised by ∆T-driven stress and mortality associated with vascular failure. With acclimation, the ∆Ca-driven boost in NPP and stand biomass (C storage) was accentuated for cooler futures but negated for warmer futures by a ∆T-driven reduction in NPP and biomass. Thus, hotter futures reduced forest biomass through either mortality or acclimation. Forest outcomes depended on whether projected climatic ∆Ca/∆T ratios were above or below physiological thresholds that neutralized the negative impacts of warming. Critically, if forests do not acclimate, the ∆Ca/∆T must be aboveca. 89 ppm⋅°C−1to avoid chronic stress, a threshold met by 55% of climate projections. If forests do acclimate, the ∆Ca/∆T must rise aboveca. 67 ppm⋅°C−1for NPP and biomass to increase, a lower threshold met by 71% of projections.
Human iPSC-derived microglia assume a primary microglia-like state after transplantation into the neonatal mouse brain
Authors: Svoboda Devon S. , Barrasa M. Inmaculada , Shu Jian , Rietjens Rosalie , Zhang Shupei , Mitalipova Maya , Berube Peter , Fu Dongdong , Shultz Leonard D. , Bell George W. , Jaenisch Rudolf
Published: November 2019

Microglia are essential for maintenance of normal brain function, with dysregulation contributing to numerous neurological diseases. Protocols have been developed to derive microglia-like cells from human induced pluripotent stem cells (hiPSCs). However, primary microglia display major differences in morphology and gene expression when grown in culture, including down-regulation of signature microglial genes. Thus, in vitro differentiated microglia may not accurately represent resting primary microglia. To address this issue, we transplanted microglial precursors derived in vitro from hiPSCs into neonatal mouse brains and found that the cells acquired characteristic microglial morphology and gene expression signatures that closely resembled primary human microglia. Single-cell RNA-sequencing analysis of transplanted microglia showed similar cellular heterogeneity as primary human cells. Thus, hiPSCs-derived microglia transplanted into the neonatal mouse brain assume a phenotype and gene expression signature resembling that of resting microglia residing in the human brain, making chimeras a superior tool to study microglia in human disease.
Probing transient excited states of the bacterial cell division regulator MinE by relaxation dispersion NMR spectroscopy
Authors: Cai Mengli , Huang Ying , Shen Yang , Li Min , Mizuuchi Michiyo , Ghirlando Rodolfo , Mizuuchi Kiyoshi , Clore G. Marius
Published: November 2019

Bacterial MinD and MinE form a standing oscillatory wave which positions the cell division inhibitor MinC, that binds MinD, everywhere on the membrane except at the midpoint of the cell, ensuring midcell positioning of the cytokinetic septum. During this process MinE undergoes fold switching as it interacts with different partners. We explore the exchange dynamics between major and excited states of the MinE dimer in 3 forms using
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N relaxation dispersion NMR: the full-length protein (6-stranded β-sheet sandwiched between 4 helices) representing the resting state; a 10-residue N-terminal deletion (Δ10) mimicking the membrane-binding competent state where the N-terminal helix is detached to interact with membrane; and N-terminal deletions of either 30 (Δ30) or 10 residues with an I24N mutation (Δ10/I24N), in which the β1-strands at the dimer interface are extruded and available to bind MinD, leaving behind a 4-stranded β-sheet. Full-length MinE samples 2 “excited” states: The first is similar to a full-length/Δ10 heterodimer; the second, also sampled by Δ10, is either similar to or well along the pathway toward the 4-stranded β-sheet form. Both Δ30 and Δ10/I24N sample 2 excited species: The first may involve destabilization of the β3- and β3′-strands at the dimer interface; changes in the second are more extensive, involving further disruption of secondary structure, possibly representing an ensemble of states on the pathway toward restoration of the resting state. The quantitative information on MinE conformational dynamics involving these excited states is crucial for understanding the oscillation pattern self-organization by MinD–MinE interaction dynamics on the membrane.
Universal phase behaviors of intracellular lipid droplets
Authors: Shimobayashi Shunsuke F. , Ohsaki Yuki
Published: November 2019

Significance

There is growing evidence suggesting that intracellular phase transitions play roles in biological functions. However, little is known about phase transitions of lipid droplets that are organelles involved in energy homeostasis. Here, we demonstrate a universal intracellular phase diagram of lipid droplets, consistent with the in vitro phase diagram, and reveal that cholesterol esters cause the liquid–liquid crystal phase transition under near-physiological conditions. We moreover combine in vivo and in vitro studies, together with the theory of confined liquid crystals, to suggest that the radial molecular alignments in the liquid crystallized lipid droplets are caused by an anchoring force at the droplet surface. These findings pave the way for a better understanding of their biological functions and diseases.
Mapping micrometer-scale wetting properties of superhydrophobic surfaces
Authors: Daniel Dan , Lay Chee Leng , Sng Anqi , Jun Lee Coryl Jing , Jin Neo Darren Chi , Ling Xing Yi , Tomczak Nikodem
Published: November 2019

There is a huge interest in developing superrepellent surfaces for antifouling and heat-transfer applications. To characterize the wetting properties of such surfaces, the most common approach is to place a millimetric-sized droplet and measure its contact angles. The adhesion and friction forces can then be inferred indirectly using Furmidge’s relation. While easy to implement, contact angle measurements are semiquantitative and cannot resolve wetting variations on a surface. Here, we attach a micrometric-sized droplet to an atomic force microscope cantilever to directly measure adhesion and friction forces with nanonewton force resolutions. We spatially map the micrometer-scale wetting properties of superhydrophobic surfaces and observe the time-resolved pinning–depinning dynamics as the droplet detaches from or moves across the surface.
Spiritual leadership development: An exemplar protocol
Authors: Chappell Stacie F. , Delbecq Andre L. , McCready William C.
Published: November 2019

The nexus of spirituality and leadership infuses many leadership theories. However, there is a gap in our understanding regarding how organizations integrate spirituality with leadership development. This article makes a significant contribution to understanding the intersection of spirituality and leadership development by examining a specific facilitation protocol. It is a natural bookend to the seminal article titled “Spirituality for Business Leadership: Reporting on a pilot course for MBA’s and CEO’s” in which André shared his first attempt at such work. In contrast, the protocol discussed in this article has been refined by André’s continued leadership and practice in this area. As well, this protocol was designed and implemented as a formal leadership development initiative within an organization. In this paper, we begin with a literature review on spiritual leadership development: the intersection of spirituality, leadership and learning; the primacy of contemplative practice; and the importance of structure. Second, we describe a leadership development program design that explicitly integrates spirituality. Finally, we discuss the implications of this protocol for future practice and research on spiritual leadership development.
Dichotic listening training following neurological injury in adults
Authors: Purdy Mary , McCullagh Jennifer
Published: November 2019

Purpose:

Injury to the dominant left brain hemisphere can lead to specific language deficits such as aphasia, or to the cognitive processes that support language such as attention and working memory. Language is heavily supported through the auditory modality, which is a key area of deficit in acquired language disorders, and recovery of auditory processing is a prerequisite to recovery of other language modalities. A specific auditory processing deficit that has been identified following neurologic injury is dichotic listening. Some researchers have suggested that dichotic listening can be strengthened through the use of a dichotic listening training paradigm, although the impact of this training for adults with neurological injury is unknown. The purpose of this study was to determine whether dichotic listening training improved dichotic listening performance as well as auditory comprehension in individuals with neurological injuries.

Method:

Five individuals with a history of acquired language deficits who met specific inclusion and exclusion criteria participated in the dichotic listening training for four to six weeks. Dichotic listening and language comprehension skills were evaluated pre- and post-training.

Results:

Results indicated all participants progressed through a range of dichotic listening tasks during training, and four of the five individuals improved on at least one of the dichotic listening tests post-treatment. All of the participants demonstrated some improvement in auditory processing/comprehension of complex commands.

Conclusions:

Dichotic listening training has the potential to positively influence dichotic listening and auditory comprehension skills in adults with neurological injury.
The optimal parameters of the laser triangulation modified thickness meter
Authors: Adamov A A , Khramov V N
Published: November 2019

In this paper, we search for optimal installation parameters for measuring the thickness of biological tissues. We created the mathematical model of the meter and researched various configurations of the constituent parts of the model. We also proposed the methods for determining the optimal parameters and we found numerical values the most important cases. We considered different options for modifying the laser triangulation method and proposed a scheme of the measurement setup. We conducted experiments and represented the results obtained with computer processing too.
The control system elements of the new generation optical switching cell
Authors: Barabanova E A , Vytovtov K A , Nguyen T T
Published: November 2019

In this paper calculation of new optical switch parameters that allows us to create next generation all-optical non-blocking switching system without external control devices is carried out for the first time. In particular, switching cell control device is studied in detail. The presented one includes Bragg filter, frequency detector, optical isolator, and former of a control signal. Here we also present the detail description and the numerical calculations of these devices for third transparent window (1550nm). The reflection and transmission coefficients are obtained, the passbands of the Bragg filter are presented, and the amplitude characteristic of the frequency detector is calculated.
Creation of zinc oxide based nanomaterials by repetitively pulsed laser treatment
Authors: Murzin S P , Safin A I , Blokhin M V
Published: November 2019

By repetitively pulsed laser treatment with a frequency of 500 Hz was metal/semiconductor nanocomposite on a basis of zinc oxide nanowires created. An analysis of results made it possible to find that with described laser-induced vibroexcitation of samples, vibration speed increases for frequencies multiple to frequency of the initial oscillation, and when frequency is increasing the amplitude is decreasing. Samples heating particularities in consequence of laser irradiation were determined. Analysis of X-ray diffraction images showed that the zinc oxide creation on the porous copper-zinc alloy substrate occurs as a result thermal oxidation by the repetitively pulsed laser treatment. It is shown that intensification condition of mass transfer in a solid state of a metal material is a local non-stationary deformation that is produced by a highly-powered outer action. Using of synergies of thermal action and vibrations in a sound frequency range caused by laser irradiation, provides opportunity of a new approach realization for the structures creation of composite nanomaterials on a basis of zinc oxide in metal/semiconductor Cu/ZnO nanocomposite.
Multiport optical power splitter design based on coupled-mode theory
Authors: Butt M A , Kozlova E S
Published: November 2019

We proposed a multiport T-shaped 1 x 8 balanced optical power splitter design based on asymmetric vertical silicon slot waveguides working on the principle of coupled-mode theory (CMT). The scheme of the power splitter is unique which offers strong field confinement of TE-polarized light and delivers the light to four ports each on two opposite side of the chip. By shifting the slot towards the outer sideline of the bend, the bending losses are reduced to 80% as compared to standard symmetric slot waveguide.
Research and modeling of laser ablation by ultra-short laser pulses for metal targets
Authors: Davydov R V , Antonov V I
Published: November 2019

In this article a new mathematical model for a laser metal ablation by ultra-short duration laser pulses is proposed. The computational process is based on a two-temperature hydrodynamic model for electrons and ions. Some improvements are made and wide-range equation of state for metals is included in model. The results of the computer simulation of ablation depth for aluminum and copper are compared with experimental data at a different laser fluency values. We obtained a good agreement between the experimental and calculated data on the ablation depth.
Metalens for creation of the longitudinally polarized photonic needle
Authors: Khonina S N , Savelyev D A , Degtyarev S A , Azizian-Kalandaragh Y
Published: November 2019

In this work, we develop a mathematical apparatus to describe continuous subwavelength diffraction gratings for creation of cylindrical beams with arbitrary order. We consider special degenerated cases of gratings periods expressions and propose to introduce nonlinearity to avoid these cases. Also, we propose a metalens based on subwavelength relief that is intended to create the longitudinally polarized photonic needle. The element combines two functions: polarization and phase transformation of the incident beam. The element transforms the incident linearly polarized beam into the radially polarized beam. Simultaneously, the incident field is provided with axicon phase. The numerical simulation is provided with Comsol software. The simulation verifies the efficient creation of longitudinally polarized photonics needle.
Dynamics of two dipole-coupled superconducting qubits interacting with two independent cavity modes
Authors: Evseev M M , Bashkirov E K
Published: November 2019

In this paper, we have investigated the entanglement dynamics between two dipole-coupled superconducting qubits not resonantly interacting with two microwave modes of independent coplanar resonators. The case of different atom-field couplings has been under consideration. Using the dressed-states technique we have derived the exact solution of the evolution equation for separable initial qubits states and field modes in the vacuum states. On its basis the negativity as a measure of qubit-qubit entanglement has been calculated. The time dependence of negativity for different values of detuning between the qubits and fields frequencies, atom-field couplings and strength of the dipole-dipole interaction has been investigated for different separable initial qubits states.
In uence of Stark shift and detuning on atomic entanglement induced by a thermal eld of one-mode cavity
Authors: Gulsyannikova M O , Bashkirov E K
Published: November 2019

We considered a quantum model consisting of two effective two-level atoms not resonantly interacting with a single-mode thermal cavity eld through two-photon transitions. We explored the entanglement dynamics between two atoms, and studied the effect of the Stark shift and detuning on the entanglement. The results showed that for a separable initial atomic state the Stark shift and detuning enhance the amount of atom-atom entanglement induced by the thermal eld. For entangled atomic state these reduce the atom-atom entanglement oscillations.