bluuebunny/crossref_metadata_2025 huggingface dataset:
Boundary slip phenomena in multicomponent gas mixtures
Authors: Stepanenko A. A. , Zaznoba V. A. , Zhdanov V. M.
Published: June 2019

The slip phenomena in multicomponent gas mixtures are studied. The moment equations, derived from the linearized Boltzmann equation by using the 13-moment approximation of the Grad’s method, are used to obtain the full (containing the contribution from the Knudsen layer) and asymptotic (valid far from the plane physical boundary of the domain) expressions for the nonequilibrium macroscopic parameters of the mixture species. The latter relations are employed to deduce the expressions for the mixture slip velocity and the viscous, thermal, and diffusion slip coefficients by using the modified Maxwell method and the diffuse-specular model of molecule scattering on the wall. The derived relations for the slip coefficients are given in the convenient form expressed in terms of basic transport coefficients, such as partial viscosity and thermal conductivity coefficients, diffusion and thermal diffusion coefficients, and coefficients of molecule momentum accommodation at the wall. The expressions found are used to calculate the slip coefficients for binary (He-Ar) and ternary (He-Ar-Xe) gas mixtures. The numerical results are in good agreement with the data calculated by using other methods.
Effects of gas cluster ion beam sputtering on the molecular orientation of organic semiconductor films: Ultraviolet photoelectron spectroscopy study of [6]phenacene
Authors: Arai Ryoji , Nishi Toshio , Kudo Yoshihiro , Yoshida Hiroyuki , Tomiya Shigetaka
Published: June 2019

The alignment of organic layer and metal layer energy levels within organic semiconductor devices is critical for efficient charge injection/collection at the electrodes. The electronic structure at the interface is usually examined using ultraviolet photoelectron spectroscopy (UPS) as the film thickness of the organic layer is built up incrementally (bottom-up method). As such, the morphology and crystallinity of the films that are examined using this technique may be different from the films used in actual devices because these properties are sensitive to the way in which the films are prepared. We have prepared [6]phenacene thin films with standing and lying molecular orientations on naturally oxidized silicon (SiO2) and highly oriented pyrolytic graphite (HOPG) surfaces, respectively. UPS measurements were performed on films that were incrementally decreased in thickness using gas cluster ion beam (GCIB) sputtering (top-down method). The spectral shapes and ionization energies of the films that were formed using the bottom-up and top-down methods were similar. Importantly, the characteristic features of a monolayer on the HOPG substrate were also observed when a thick film (i.e., not built up in layers using the bottom-up method) was thinned down by GCIB sputtering. We have shown that UPS combined with GCIB sputtering is a useful technique for examining the energy level alignment of interfaces within films that are fabricated using conditions similar to those used for real devices.
Simultaneous in vivo measurements of the total hemoglobin, oxygen saturation, and tissue blood flow via hybrid near-infrared diffuse optical techniques
Authors: Wang Detian , Wang Long , Gao Peng , Shi Ruiqiang , Zhu Liguo , Peng Qixian , Li Zeren , Zhao Jianheng , Chen Tunan , Li Fei , Feng Hua
Published: June 2019

Diagnosing a stroke at an emergency site is an important potential clinical application for near-infrared light techniques. We have fabricated a hybrid diffuse optical device that combines diffuse optical spectroscopy and diffuse correlation spectroscopy (DCS) to monitor the total hemoglobin concentration (HbT), tissue oxygen saturation (StO2), and blood flow index (BFI) of a patient. The device used hybrid light sources consisting of three incoherent laser diodes (LDs) and one long coherent LD. Single-photon-counting avalanche photodiodes detected light reemitted from the tissue. Arm cuff experiments were performed using a healthy subject to validate device capabilities. Changes in hemodynamic parameters including the HbT, StO2, and BFI were measured continuously during the arm cuff experiments. The StO2 decreased linearly from 63% to 51% during the 3 min occlusion period. The blood flow decreased immediately by 16% when the occlusion was placed on the forearm. Overshot increases in the HbT, StO2, and BFI were all observed after occlusion release. Stroke is related to abnormal hemodynamic changes in cerebral vasculature and our device is sensitive to such changes. Thus, we believe that the hybrid device developed here may have potential clinical applications for stroke diagnosis at emergency sites.
High-accuracy extrapolated ab initio thermochemistry. IV. A modified recipe for computational efficiency
Authors: Thorpe James H. , Lopez Chris A. , Nguyen Thanh Lam , Baraban Joshua H. , Bross David H. , Ruscic Branko , Stanton John F.
Published: June 2019

A number of economical modifications to the high-accuracy extrapolated ab initio thermochemistry (HEAT) model chemistry are evaluated. The two resulting schemes, designated as mHEAT and mHEAT+, are designed for efficient and pragmatic evaluation of molecular energies in systems somewhat larger than can be practically studied by the unapproximated HEAT scheme. It is found that mHEAT+ produces heats of formation with nearly subchemical (±1 kJ/mol) accuracy at a substantially reduced cost relative to the full scheme. Total atomization energies calculated using the new thermochemical recipes are compared to the results of the HEAT-345(Q) model chemistry, and enthalpies of formation for the three protocols are also compared to Active Thermochemical Tables. Finally, a small selection of transition states is studied using mHEAT and mHEAT+, which illuminates some interesting features of reaction barriers and serves as an initial benchmark of the performance of these model chemistries for chemical kinetics applications.
Fabrication and experimental demonstration of a hybrid resonant acoustic gradient index metasurface at 40 kHz
Authors: Gerard Nikhil JRK , Cui Huachen , Shen Chen , Xie Yangbo , Cummer Steven , Zheng Xiaoyu , Jing Yun
Published: June 2019

Over the past few years, acoustic gradient index metasurfaces (GIMs) have been actively studied for the numerous wave control capabilities that they facilitate. Previous research, however, has primarily focused on GIMs that operate in the audible frequency range, due to the difficulties in fabricating such intricate structures at the millimeter and submillimeter scales, for ultrasonic applications. In this work, we design, fabricate, and experimentally demonstrate the working of a hybrid resonant acoustic gradient index metasurface for airborne ultrasound at 40 kHz. The fabrication of such a GIM is made possible by projection microstereolithography, an emerging additive manufacturing technique. Numerical simulations were conducted to verify the metasurface design, and experiments were performed to corroborate these simulations. The stronger dissipation associated with airborne ultrasound is highlighted in this paper. The experimental demonstration of such a metasurface for airborne ultrasound could further its prospects as a candidate for miniaturized acoustic devices.
An active Bonner sphere spectrometer capable of intense neutron field measurement
Authors: Hu Z. M. , Ge L. J. , Sun J. Q. , Zhang Y. M. , Du T. F. , Peng X. Y. , Chen J. , Zhang H. , Nocente M. , Rebai M. , Croci G. , Tardocchi M. , Gorini G. , Hu L. Q. , Zhong G. Q. , Zhou R. J. , Chen J. X. , Li X. Q. , Fan T. S.
Published: June 2019

A Bonner sphere spectrometer (BSS) was developed compensating for the lack of active BSSs for intense neutron field characterization. The spectrometer combines the merits of present active and passive BSSs, namely, online data acquisition capability and intense neutron field resistance, respectively. The key elements of the development are the utilization of diamond detectors as thermal neutron sensors of BSSs and the incorporation of the air gap into the design of the diamond detector for optimizing the pulse height spectrum in order to enhance the rejection capability to γ ray backgrounds and to decrease the impacts of spectrometer instabilities. A two-step method capable of >100 times of calculation time saving compared to the whole geometry model was suggested to establish the response function for neutrons below 20 MeV whose reliability was verified by the two other models. The applicability of the BSS to intense neutron field characterization was demonstrated by the good performance in the Experimental Advanced Superconducting Tokamak (EAST) neutron field with an emission rate of ∼1013–1014 neutrons/s. The spectrometer is dedicated to the characterization of intense neutron fields around tokamaks. These devices may find an application in future tokamaks, such as the International Thermonuclear Experimental Reactor, the Demonstration Power Station, and the China Fusion Engineering Test Reactor, whose neutron emission rates will be >104 times higher than those of current tokamaks.
A comparative study of electron-impact cross sections of C4F6 isomers from 15 to 5000 eV
Authors: Bharadvaja Anand , Kaur Savinder , Baluja K. L.
Published: June 2019

Electron-impact differential, integral, and momentum transfer cross sections (CS) are computed for C4F6 isomers from 15 to 5000 eV by employing the Single Center Expansion formalism. The molecular wavefunctions of isomers are obtained using the multicenter expansion of Gaussian-type orbitals within the single determinant Hartree-Fock self-consistent field scheme. The electron-molecule interaction is modeled by summing the static, exchange, and correlation-polarization types of potentials. The exchange and correlation-polarization potentials account for the indistinguishability of incident electron and target electrons and the distortion of charge density of target by the impinging electron, respectively. The multipole expansion of the target at center of mass includes the dipole and higher order terms. The local description of potential permits us to rewrite the scattering radial equations in a simplified form. The electron impact ionization CS are obtained using the Binary-Encounter-Bethe model. The elastic and inelastic CS are summed incoherently to obtain total CS over a wide energy range. A good agreement is observed with the available data for different types of CS obtained.
Investigation of high X-ray conversion efficiency Kr filled gas sources at the National Ignition Facility
Authors: May M. J. , Kemp G. E. , Colvin J. D. , Liedahl D. A. , Poole P. L. , Thorn D. B. , Widmann K. , Benjamin R. , Barrios M. A. , Blue B. E.
Published: June 2019

We report on the performance of high x-ray fluence Kr K-shell sources that are being developed for high energy density experiments. These targets are 4.1 mm in diameter 4.4 mm tall hollow epoxy tubes having a 40 μm thick wall holding 1.5 atm of Kr gas. For these shots, the National Ignition Facility laser delivered a nominally constant total energy of ≈750 kJ of 351 nm (3ω) light at the three power levels [e.g., ≈120 (low), ≈145 (medium), and ≈210 TW (high)]. The Kr K-shell (Ephoton = 8–20 keV) x-ray radiant intensity and radiant energy (kJ/sr) of these sources were found to increase as a function of laser power but began to plateau at the highest laser power. The Kr K-shell radiant energy increased from ≈1 kJ/sr at ≈120 TW to ≈2 kJ/sr at ≈210 TW. Radiation hydrodynamics simulations predict radiant energies to be always higher than these measurements. The increase in K-shell emission is attributed to its strong dependence on the electron temperature. Electron temperature distributions were inferred from measured Heα and Lyα line emission through the use of a genetic algorithm and Scram modeling. The inferred temperatures from the experiment are 20% to 30% higher than those predicted from modeling.
Formation of the orthorhombic phase in CeO2-HfO2 solid solution epitaxial thin films and their ferroelectric properties
Authors: Shiraishi T. , Choi S. , Kiguchi T. , Shimizu T. , Funakubo H. , Konno T. J.
Published: June 2019

The formation of the metastable orthorhombic phase (Pca21) in CeO2-HfO2 solid solution epitaxial thin films has been demonstrated. The films were deposited at room temperature on (001)yttria stabilized zirconia substrates by an Ar ion-beam sputtering method and subsequent annealing, where the Ce content of the films was controlled by changing the composition, x = [CeO2]/([HfO2]+[CeO2]), of the sputtering target. The chemical states of cations in xCeO2 − (1 − x)HfO2 (x = 0–0.5) thin films have been investigated by X-ray photoelectron spectroscopy, which confirmed the coexistence of Ce4+ and Ce3+. The crystal structure has been investigated by using X-ray diffraction and transmission electron microscopy. These analyses revealed that the metastable orthorhombic phase was formed in the films with x = 0.03–0.1, and the lattice constants of that phase increased with the Ce content. Microstructural analysis has been performed by using scanning transmission electron microscopy, which revealed a multidomain structure consisting of the orthorhombic phase. The polarization-electric field loop for the film with x = 0.1 indicated ferroelectricity, demonstrating that CeO2-HfO2 solid solution thin films are candidates for fluorite-type ferroelectrics.
Fano resonance of collective excitations in 1D plasmonic crystal
Authors: Akbari-Moghanjoughi M.
Published: June 2019

The quantum coupled pseudoforce model with the damping term is used to study the plasmon excitations in a variety of systems. Damped plasmon excitations can be used to model different physical situations such as the plasmon penetration into insulating environments and surface plasmon excitations in semiconductors. The application of the pseudoforce model with damping around a charged Dirac sheet reveals that such pseudoforce system can also be used to model the charge shielding. It is also observed that quantum charge shielding possesses two-tone field-density variations due to both single-particle oscillations and collective electrostatic excitations. The effect of uniform electric field on the damped plasmon excitations is also considered in this paper. We further report new findings concerning the effect of collective quantum excitations which may provide further insight into the theory of bandgap structure in crystals. It is remarked that the presence of charge screening in a periodic lattice can lead to Fano resonance. Finally, a new expression for the charge-particle continuity equation in the presence of shielding effect is presented. Current investigation can have fundamental results for better understanding of the quantum transport phenomenon and optical properties of semiconductors, metallic compounds, nanoclusters, and plasmonic crystals.
An experimental and theoretical study of the C 1s ionization satellites in CH3I
Authors: Trofimov A. B. , Belogolova A. M. , Serebrennikova S. A. , Forbes R. , Pratt S. T. , Holland D. M. P.
Published: June 2019

The C 1s ionization spectrum of CH3I has been studied both experimentally and theoretically. Synchrotron radiation has been employed to record polarization dependent photoelectron spectra at a photon energy of 614 eV. These spectra encompass the main-line due to the C 1s single-hole state and the peaks associated with the shake-up satellites. Vertical ionization energies and relative photoelectron intensities have been computed using the fourth-order algebraic-diagrammatic construction approximation scheme for the one-particle Green’s function and the 6-311++G** basis set. The theoretical spectrum derived from these calculations agrees qualitatively with the experimental results, thereby allowing the principal spectral features to be assigned. According to our calculations, two 2A1 shake-up states of the C 1s−1 σCI → σCI* type with singlet and triplet intermediate coupling of the electron spins (S′ = 0, 1) play an important role in the spectrum and contribute significantly to the overall intensity. Both of these states are expected to have dissociative diabatic potential energy surfaces with respect to the C–I separation. Whereas the upper of these states perturbs the manifold of Rydberg states, the lower state forms a band which is characterized by a strongly increased width. Our results indicate that the lowest shake-up peak with significant spectral intensity is due to the pair (S′ = 0, 1) of 2E (C 1s−1 I 5p → σCI*) states. We predict that these 2E states acquire photoelectron intensity due to spin-orbit interaction. Such interactions play an important role here due to the involvement of the I 5p orbitals.
Effect of particle size ratio on shear-induced onset of particle motion at low particle Reynolds numbers: From high shielding to roughness
Authors: Topic N. , Retzepoglu S. , Wensing M. , Illigmann C. , Luzi G. , Agudo J. R. , Wierschem A.
Published: June 2019

We study incipient motion of single beads on regular substrates made of spherical particles of a different size in steady shear flow at small particle Reynolds numbers. We cover a large range of sizes: from small beads that are highly shielded from the shear flow by the substrate spheres, and hence, are susceptible to the flow through the interstices of the substrate, to beads fully exposed to the flow, where the substrate rather acts like roughness of an otherwise flat surface. Numerical and experimental studies agree within measurement uncertainty. To describe the findings, we extend a recently derived model for particles of equal size which was validated over a wide range of substrates [Agudo et al., “Shear-induced incipient motion of a single sphere on uniform substrates at low particle Reynolds numbers,” J. Fluid Mech. 825, 284–314 (2017)]. The extended model covers the entire spectrum of size ratios, where the critical Shields number varies from about zero to infinity. The model properly describes the numerical and experimental data. For well exposed beads, we find a scaling law between the critical Shields number and the size ratio between mobile bead and substrate spheres with an exponent of −1.
Amphiphilic multicomponent molecular brushes
Authors: Ivanov Ivan V. , Meleshko Tamara K. , Kashina Anna V. , Yakimansky Alexander V.
Published: June 2019

Multicomponent molecular brushes containing amphiphilic polymer moieties are promising objects of research of macromolecular chemistry. The development of stimulus-responsive systems sensitive to changes in environmental parameters, based on the molecular brushes, opens up new possibilities for their applications in medicine, biochemistry and microelectronics. The review presents the current understanding of the structures of main types of amphiphilic multicomponent brushes, depending on the chemical nature and type of coupling of the backbone and side chains. The approaches to the controlled synthesis of multicomponent molecular brushes of different architecture are analyzed. Self-assembly processes of multicomponent molecular brushes in selective solvents are considered.

The bibliography includes 259 references.
Redox-Initiated Reversible Addition–Fragmentation Chain Transfer (RAFT) Polymerization
Authors: Reyhani Amin , McKenzie Thomas G. , Fu Qiang , Qiao Greg G.
Published: June 2019

Reversible addition–fragmentation chain transfer (RAFT) polymerization initiated by a radical-forming redox reaction between a reducing and an oxidizing agent (i.e. ‘redox RAFT’) represents a simple, versatile, and highly useful platform for controlled polymer synthesis. Herein, the potency of a wide range of redox initiation systems including enzyme-mediated redox reactions, the Fenton reaction, peroxide-based reactions, and metal-catalyzed redox reactions, and their application in initiating RAFT polymerization, are reviewed. These redox-RAFT polymerization methods have been widely studied for synthesizing a broad range of homo- and co-polymers with tailored molecular weights, compositions, and (macro)molecular structures. It has been demonstrated that redox-RAFT polymerization holds particular promise due to its excellent performance under mild conditions, typically operating at room temperature. Redox-RAFT polymerization is therefore an important and core part of the RAFT methodology handbook and may be of particular importance going forward for the fabrication of polymeric biomaterials under biologically relevant conditions or in biological systems, in which naturally occurring redox reactions are prevalent.
Quantification of inter-regional differences in risk mitigation from prescribed burning across multiple management values
Authors: Cirulis Brett , Clarke Hamish , Boer Matthias , Penman Trent , Price Owen , Bradstock Ross
Published: June 2019

Fire agencies are moving towards planning systems based on risk assessment; however, knowledge of the most effective way to quantify changes in risk to key values by application of prescribed fire is generally lacking. We present a quantification and inter-regional comparison of how risk to management values responds to variations in prescribed burning treatment rate. Fire simulations were run using the PHOENIX RapidFire fire behaviour simulator for two case study landscapes in interface zones in Tasmania and the Australian Capital Territory (ACT), Australia. A Bayesian network approach used these data to explore the influence of treatment and weather on risk from wildfire. Area burnt, length of powerline damaged and length of road damaged responded more strongly to treatment in the ACT than in Tasmania, whereas treatment mitigated house loss and life loss more strongly in Tasmania than the ACT. The effect of prescribed burning treatment rate on area burnt below minimum tolerable fire interval was similar in each case study landscape. Our study shows that the effectiveness of prescribed burning at mitigating area burnt by wildfire and other key values varies considerably across landscapes and values.
1,4-Benzoquinone antimicrobial agents against
Staphylococcus aureus
and
Mycobacterium tuberculosis
derived from scorpion venom
Authors: Carcamo-Noriega Edson Norberto , Sathyamoorthi Shyam , Banerjee Shibdas , Gnanamani Elumalai , Mendoza-Trujillo Monserrat , Mata-Espinosa Dulce , Hernández-Pando Rogelio , Veytia-Bucheli José Ignacio , Possani Lourival D. , Zare Richard N.
Published: June 2019

Significance

Development of new drugs from the venom of dangerous animals (spiders, snakes, scorpions, snails) has recently attracted much chemotherapeutic interest. While most isolated and characterized venom components are found to be proteinic or peptidic in nature, here we report two 1,4-benzoquinone compounds, one red and another blue, derived from the venom of a rarely studied scorpion (
Diplocentrus melici
) indigenous to Mexico. After successful identification and synthesis of these compounds, the red and blue benzoquinones showed remarkable antimicrobial activities against
Staphylococcus aureus
and
Mycobacterium tuberculosis
, respectively. The observation that the blue compound is equally effective against normal and multidrug-resistant tuberculosis while appearing not to affect the epithelium of lungs heightens its potential as a new drug candidate.
Loss of gut barrier integrity triggers activation of islet-reactive T cells and autoimmune diabetes
Authors: Sorini Chiara , Cosorich Ilaria , Lo Conte Marta , De Giorgi Lorena , Facciotti Federica , Lucianò Roberta , Rocchi Martina , Ferrarese Roberto , Sanvito Francesca , Canducci Filippo , Falcone Marika
Published: June 2019

Significance

Functional loss of gut barrier integrity with subsequent increased antigen trafficking and occurrence of low-grade intestinal inflammation precede the onset of type 1 diabetes (T1D) in patients and preclinical models, thus suggesting that these events are mechanistically linked to the autoimmune pathogenesis of the disease. However, a causal relationship between increased intestinal permeability and autoimmune diabetes was never demonstrated. Our data show that breakage of gut barrier continuity leads to activation of islet-reactive T cells in the intestine, thus triggering autoimmune diabetes. An important implication of our findings is that restoration of a healthy gut barrier through microbiota and diet modulation in diabetes-prone individuals could reduce intestinal activation of islet-reactive T cells and prevent T1D occurrence.
Early snowmelt projected to cause population decline in a subalpine plant
Authors: Campbell Diane R.
Published: June 2019

How climate change influences the dynamics of plant populations is not well understood, as few plant studies have measured responses of vital rates to climatic variables and modeled the impact on population growth. The present study used 25 y of demographic data to analyze how survival, growth, and fecundity respond to date of spring snowmelt for a subalpine plant. Fecundity was estimated by seed production (over 15 y) and also divided into flower number, fruit set, seeds per fruit, and escape from seed predation. Despite no apparent effects on flower number, plants produced more seeds in years with later snowmelt. Survival and probability of flowering were reduced by early snowmelt in the previous year. Based on demographic models, earlier snowmelt with warming is expected to lead to negative population growth, driven especially by changes in seedling establishment and seed production. These results provide a rare example of how climate change is expected to influence the dynamics of a plant population. They furthermore illustrate the potential for strong population impacts even in the absence of more commonly reported visual signs, such as earlier blooming or reduced floral display in early melting years.
On the psychology and economics of antisocial personality
Authors: Engelmann J. B. , Schmid B. , De Dreu C. K. W. , Chumbley J. , Fehr E.
Published: June 2019

Significance

Using an interdisciplinary experimental approach grounded in behavioral economics and personality psychology, we identify an antisocial personality profile and examine its role across strategic contexts. Antisocial individuals exhibit a specific combination of behaviors and beliefs: they have a high propensity to betray others’ trust and believe that others are like them, but if given a punishment opportunity, they impose very harsh sanctions on those who betray their trust. More generally, antisocial individuals show beliefs and behaviors that are consistent with the assumption that most others are as antisocial as they themselves are.
QTL × environment interactions underlie adaptive divergence in switchgrass across a large latitudinal gradient
Authors: Lowry David B. , Lovell John T. , Zhang Li , Bonnette Jason , Fay Philip A. , Mitchell Robert B. , Lloyd-Reilley John , Boe Arvid R. , Wu Yanqi , Rouquette Francis M. , Wynia Richard L. , Weng Xiaoyu , Behrman Kathrine D. , Healey Adam , Barry Kerrie , Lipzen Anna , Bauer Diane , Sharma Aditi , Jenkins Jerry , Schmutz Jeremy , Fritschi Felix B. , Juenger Thomas E.
Published: June 2019

Local adaptation is the process by which natural selection drives adaptive phenotypic divergence across environmental gradients. Theory suggests that local adaptation results from genetic trade-offs at individual genetic loci, where adaptation to one set of environmental conditions results in a cost to fitness in alternative environments. However, the degree to which there are costs associated with local adaptation is poorly understood because most of these experiments rely on two-site reciprocal transplant experiments. Here, we quantify the benefits and costs of locally adaptive loci across 17° of latitude in a four-grandparent outbred mapping population in outcrossing switchgrass (Panicum virgatumL.), an emerging biofuel crop and dominant tallgrass species. We conducted quantitative trait locus (QTL) mapping across 10 sites, ranging from Texas to South Dakota. This analysis revealed that beneficial biomass (fitness) QTL generally incur minimal costs when transplanted to other field sites distributed over a large climatic gradient over the 2 y of our study. Therefore, locally advantageous alleles could potentially be combined across multiple loci through breeding to create high-yielding regionally adapted cultivars.
Quantifying the sensing power of vehicle fleets
Authors: O’Keeffe Kevin P. , Anjomshoaa Amin , Strogatz Steven H. , Santi Paolo , Ratti Carlo
Published: June 2019

Significance

Attaching sensors to crowd-sourced vehicles could provide a cheap and accurate way to monitor air pollution, road quality, and other aspects of a city’s health. But in order for so-called drive-by sensing to be practically useful, the sensor-equipped vehicle fleet needs to have large “sensing power”—that is, it needs to cover a large fraction of a city’s area during a given reference period. Here, we provide an analytic description of the sensing power of taxi fleets, which agrees with empirical data from nine major cities. Our results show taxis’ sensing power is unexpectedly large—in Manhattan; just 10 random taxis cover one-third of street segments daily, which certifies that drive-by sensing can be readily implemented in the real world.
Sixty-six million years along the road of mammalian ecomorphological specialization
Authors: Figueirido Borja , Palmqvist Paul , Pérez-Claros Juan A. , Janis Christine M.
Published: June 2019

Significance

The six “evolutionary faunas” of large mammal taxonomic diversity described for the North American Cenozoic have a nonrandom ecomorphological spectrum and show a long-term trend toward greater ecological specialization over the past 66 My. We show here that each successive fauna was characterized by a change toward more specialized ecotypes; these changes were correlated with vegetation shifts caused by major climatic changes, which may have promoted the appearance of new ecological opportunities and morphological innovations.
Flame-formed carbon nanoparticles exhibit quantum dot behaviors
Authors: Liu Changran , Singh Ajay V. , Saggese Chiara , Tang Quanxi , Chen Dongping , Wan Kevin , Vinciguerra Marianna , Commodo Mario , De Falco Gianluigi , Minutolo Patrizia , D’Anna Andrea , Wang Hai
Published: June 2019

Significance

Flame-formed carbon nanoparticles are observed to exhibit quantum confinement behaviors. We demonstrate that the size dependence of photoemission ionization energy in air and optical band gap of flame-generated carbon particles can be well explained by available quantum confinement theory. Carbon nanoparticles comprising mainly polycyclic aromatic hydrocarbons are widespread in nature. The results have important consequences in problems ranging from interpreting the infrared emission spectra of carbon dusts in the interstellar media, to evaluating the climate effects of atmospheric fine carbon particles, measuring soot nucleation and growth rates in flames, and developing applications of carbon nanoparticles in photovoltaic and electrochemical devices.
TMEM16A controls EGF-induced calcium signaling implicated in pancreatic cancer prognosis
Authors: Crottès David , Lin Yu-Hsiu T. , Peters Christian J. , Gilchrist John M. , Wiita Arun P. , Jan Yuh Nung , Jan Lily Yeh
Published: June 2019

Significance

Cancer of the pancreas is highly heterogeneous. Improvement of diagnosis and prognosis requires the discovery of new biomarkers and new methods of classification. In this study, we identify TMEM16A calcium-activated chloride channel as a potential key biomarker for pancreatic cancer. We demonstrate that, through the modulation of chloride homeostasis and the initiation of a calcium signaling pathway, TMEM16A is an important regulator of ligand-induced EGFR signaling in pancreatic cancer cells. Taken together, our findings establish that EGF-induced TMEM16A-dependent calcium pathways constitute a gene set sufficient for classification of pancreatic cancer, and provide inroads for molecular characterization of different subtypes of pancreatic cancer.
Symptomatic plant viroid infections in phytopathogenic fungi
Authors: Wei Shuang , Bian Ruiling , Andika Ida Bagus , Niu Erbo , Liu Qian , Kondo Hideki , Yang Liu , Zhou Hongsheng , Pang Tianxing , Lian Ziqian , Liu Xili , Wu Yunfeng , Sun Liying
Published: June 2019

Significance

Viroids are the only known autonomously replicating pathogenic agents that do not encode proteins. As viroids are known only to naturally infect plants, their infectivity and pathogenicity in other eukaryotes are largely unexplored. Herein, we demonstrate the stable infection of three viroid species in different plant pathogenic filamentous fungi and show that viroid infection can reduce the growth and virulence of fungi. In addition to successful viroid RNA inoculation of fungal spheroplasts, viroid infection of fungus could occur through viroid transmission from the plant and when viroid RNAs are directly applied to fungal mycelia. These findings are relevant to our understanding of viroid replication, transmission, and pathogenicity.
Climate-driven oscillation of phosphorus and iron limitation in the North Pacific Subtropical Gyre
Authors: Letelier Ricardo M. , Björkman Karin M. , Church Matthew J. , Hamilton Douglas S. , Mahowald Natalie M. , Scanza Rachel A. , Schneider Niklas , White Angelicque E. , Karl David M.
Published: June 2019

Significance

Characterizing the mechanisms driving spatial and temporal changes in the stoichiometry of nutrient supply is crucial to understand the controls of an ecosystem’s carrying capacity and productivity. In marine oligotrophic regions, small changes in the ocean and atmospheric nutrient input ratio can shift the nature of the limiting nutrient. The present study documents such a shift at interannual scales between periods of phosphorus limitation and sufficiency in the North Pacific Subtropical Gyre. These shifts appear to be driven by interannual variations in the transport of iron-rich Asian dust across the North Pacific resulting from basin-scale changes in atmospheric pressure gradients, as reflected by the Pacific Decadal Oscillation index, causing the ecosystem to oscillate between phosphorus and iron limitation.
Periodic catastrophes over human evolutionary history are necessary to explain the forager population paradox
Authors: Gurven Michael D. , Davison Raziel J.
Published: June 2019

Significance

Much of what is known about human life histories is based on studying modern hunter-gatherers experiencing rapid population growth. Yet, if populations are near-stationary over most of their evolutionary history, the positive growth of contemporary foragers is puzzling and potentially unrepresentative. Investigating multiple demographic scenarios in a large sample of human and chimpanzee populations, we find that periodic catastrophes combined with plausible fertility or mortality reductions can reasonably generate zero population growth. Our findings bolster arguments about the role of intergenerational cooperation and cumulative culture in supporting the colonizing potential of human populations once released from catastrophes.
Climatic shifts drove major contractions in avian latitudinal distributions throughout the Cenozoic
Authors: Saupe Erin E. , Farnsworth Alexander , Lunt Daniel J. , Sagoo Navjit , Pham Karen V. , Field Daniel J.
Published: June 2019

Many higher level avian clades are restricted to Earth’s lower latitudes, leading to historical biogeographic reconstructions favoring a Gondwanan origin of crown birds and numerous deep subclades. However, several such “tropical-restricted” clades (TRCs) are represented by stem-lineage fossils well outside the ranges of their closest living relatives, often on northern continents. To assess the drivers of these geographic disjunctions, we combined ecological niche modeling, paleoclimate models, and the early Cenozoic fossil record to examine the influence of climatic change on avian geographic distributions over the last ∼56 million years. By modeling the distribution of suitable habitable area through time, we illustrate that most Paleogene fossil-bearing localities would have been suitable for occupancy by extant TRC representatives when their stem-lineage fossils were deposited. Potentially suitable habitat for these TRCs is inferred to have become progressively restricted toward the tropics throughout the Cenozoic, culminating in relatively narrow circumtropical distributions in the present day. Our results are consistent with coarse-scale niche conservatism at the clade level and support a scenario whereby climate change over geological timescales has largely dictated the geographic distributions of many major avian clades. The distinctive modern bias toward high avian diversity at tropical latitudes for most hierarchical taxonomic levels may therefore represent a relatively recent phenomenon, overprinting a complex biogeographic history of dramatic geographic range shifts driven by Earth’s changing climate, variable persistence, and intercontinental dispersal. Earth’s current climatic trajectory portends a return to a megathermal state, which may dramatically influence the geographic distributions of many range-restricted extant clades.
Oxidation of PKGIα mediates an endogenous adaptation to pulmonary hypertension
Authors: Rudyk Olena , Rowan Alice , Prysyazhna Oleksandra , Krasemann Susanne , Hartmann Kristin , Zhang Min , Shah Ajay M. , Ruppert Clemens , Weiss Astrid , Schermuly Ralph T. , Ida Tomoaki , Akaike Takaaki , Zhao Lan , Eaton Philip
Published: June 2019

Significance

This study demonstrates that oxidation of protein kinase G Iα (PKGIα) to its disulfide-activated state occurs in pulmonary arteries during chronic hypoxia, and that this is a protective event that limits progression of pulmonary hypertension by at least two mechanisms. Firstly, it induces pulmonary vasodilation that counters and offsets maladaptive vasoconstriction during chronic hypoxia, and, secondly, disulfide PKGIα is protective by preventing maladaptive growth and fibrosis signaling. Consistent with oxidation of PKGIα being protective, administration of polysulfides to mice during hypoxia, which increased the abundance of the disulfide form of the kinase, was therapeutic and limited disease progression.
Ruminococcus gnavus
, a member of the human gut microbiome associated with Crohn’s disease, produces an inflammatory polysaccharide
Authors: Henke Matthew T. , Kenny Douglas J. , Cassilly Chelsi D. , Vlamakis Hera , Xavier Ramnik J. , Clardy Jon
Published: June 2019

Significance

The bacteria that live within the human gut play crucial roles in regulating our primary metabolism, protecting us from pathogens, and developing our immune system. Imbalances in bacterial community structure have been implicated in many diseases, such as Crohn’s disease, an inflammatory bowel disease. We found and characterized an inflammatory polysaccharide produced by the gut bacterium
Ruminococcus gnavus
, populations of which bloom during flares of symptoms in patients with Crohn’s disease. This molecule induces the production of inflammatory cytokines like TNFα by dendritic cells and may contribute to the association between
R. gnavus
and Crohn’s disease. This work establishes a plausible molecular mechanism that may explain the association between a member of the gut microbiome and an inflammatory disease.
Defects in the origin licensing checkpoint stresses cells exiting G0
Authors: Blow J. Julian
Published: June 2019

The full licensing of replication origins in late G1 is normally enforced by the licensing checkpoint. In this issue, Matson et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201902143) show that this checkpoint is inoperative in cells exiting from G0, resulting in incomplete origin licensing and consequent replicative stress.
Differential invariants of Kundt waves
Authors: Kruglikov Boris , McNutt David , Schneider Eivind
Published: June 2019

Kundt waves belong to the class of spacetimes which are not distinguished by their scalar curvature invariants. We address the equivalence problem for the metrics in this class via scalar differential invariants with respect to the equivalence pseudo-group of the problem. We compute and finitely represent the algebra of those on the generic stratum and also specify the behavior for vacuum Kundt waves. The results are then compared to the invariants computed by the Cartan–Karlhede algorithm.
Coherent coupling of single molecules to on-chip ring resonators
Authors: Rattenbacher Dominik , Shkarin Alexey , Renger Jan , Utikal Tobias , Götzinger Stephan , Sandoghdar Vahid
Published: June 2019

We report on cryogenic coupling of organic molecules to ring microresonators obtained by looping subwavelength waveguides (nanoguides). We discuss fabrication and characterization of the chip-based nanophotonic elements which yield a resonator finesse in the order of 20 when covered by molecular crystals. Our observed extinction dips from single molecules reach 22%, consistent with an expected enhancement factor of up to 11 for the molecular emission into the nanoguide. Future efforts will aim at efficient coupling of a handful of molecules via their interaction with a ring microresonator mode, setting the ground for the realization of quantum optical cooperative effects.
Negative differential response in chemical reactions
Authors: Falasco Gianmaria , Cossetto Tommaso , Penocchio Emanuele , Esposito Massimiliano
Published: June 2019

Reaction currents in chemical networks usually increase when increasing their driving affinities. But far from equilibrium the opposite can also happen. We find that such negative differential response (NDR) occurs in reaction schemes of major biological relevance, namely, substrate inhibition and autocatalysis. We do so by deriving the full counting statistics of two minimal representative models using large deviation methods. We argue that NDR implies the existence of optimal affinities that maximize the robustness against environmental and intrinsic noise at intermediate values of dissipation. An analogous behavior is found in dissipative self-assembly, for which we identify the optimal working conditions set by NDR.
Passive survivability of buildings under changing urban climates across eight US cities
Authors: Baniassadi Amir , Sailor David J , Krayenhoff E Scott , Broadbent Ashley M , Georgescu Matei
Published: June 2019

In the US, more than 80% of fatal cases of heat exposure are reported in urban areas. Notably, indoor exposure is implicated in nearly half of such cases, and lack of functioning air conditioning (AC) is the predominant cause of overheating. For residents with limited capacity to purchase, maintain, and operate an AC system, or during summertime power outages, the ability of buildings to maintain safe thermal conditions without mechanical cooling is the primary protective factor against heat. In this paper, we use whole-building energy simulations to compare indoor air temperature inside archetypical single-family residential buildings without AC at the start and middle of the century in eight US cities. We ran the models using hourly output from 10 year regional climate simulations that explicitly include heating from mid-century projections of urban development and climate change under a ‘business-as-usual’ emissions scenario. Moreover, to identify the impacts from evolving construction practices, we compare different versions of building energy standards. Our analysis shows that summertime overheat time may increase by up to 25% by the middle of century. Moreover, we find that, while newer building energy codes reduce thermal comfort under moderate outdoor weather, they perform better under extreme heat.
Screening of polyhydroxyalkanoates (PHA)-producing bacteria from soil bacteria strains
Authors: Ratnaningrum D , Saraswaty V , Priatni S , Lisdiyanti P , Purnomo A , Pudjiraharti S
Published: June 2019

Plastic wastes and petrochemical-based polymer materials have become a serious problem to the environment due to the characteristics of these materials that are difficult to degrade in nature. Polyhydroxyalkanoates (PHA) is one type of biodegradable plastics that have a great potential to replace the widely-used hydrocarbon plastics since it will decompose completely into carbon dioxide and water after burial for several months in the soil. PHA can be produced by microorganisms such as bacteria and algae through a fermentation process. The objective of this research is to obtain bacteria that can produce PHA. Screening was carried out by two sequential steps, qualitative and followed by quantitative methods. An amount of 29 bacteria strains isolated from Indonesians soil were screened for this purpose. The qualitative screening was conducted by growing the bacteria in a specific medium containing Nile red dye. The results showed that 19 strains were positive, generated pink to orange colonies under UV light at 235 nm. It was also confirmed by fluorescence microscope. The quantitative screening was performed by measuring the intracellular materials (predicted as PHA) of the bacterial cells by gravimetric method. The results indicated that the highest average of PHA content was 52.9%, 35.6% and 35.4 of dried cell weight, respectively for the Burkholderia sp B73, Bacillus sp B58, Bacillus toyonensis B50 and Staphylococcus cohni B66.
Antioxidant activity of biocellulose-based films incorporated with powder of soursop leaves (Annona muricata L)
Authors: Srikandace Y , Indriyati
Published: June 2019

Biocelluloses are natural materials that are produced from Acetobacter sp through fermentation in coconut water as the medium. In this study, biocellulose-based edible film was used as the carrier film for the antioxidant agents (the soursop leave powder (Annona muricata L)). This leave is considered as a good source of natural antioxidant, while all parts of the fruit are used in traditional medicine. This work aimed to evaluate the antioxidant activity of biocellulose-based edible film added with soursop leave powder. The biocellulose was formed in slurry and leaves of fruit was crushed into powder. The edible films were prepared by mixing biocellulose slurry, carboxy methyl cellulose (CMC) as the homogenizer, and the leaves powder, casting, and drying in the oven at 40 °C for 24 h. The IC50 of methanol extract of leaves powder and edible film containing 0.2 g leaves powder were 89.89 mg/mL and 363.26 mg/mL, respectively. All methanol extracts of edible films incorporated with soursop leaves powder inhibited DPPH about 71.10-86.80% and they remained above 70% after storage in a plastic bag at room temperature for one month. The edible films also had the thickness of 0.040-0.067 mm, the solubility of 80.30-90.20% and all compounds of edible films were still available based on SEM and FTIR results.