bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of damped oscillation associated spectra from ultrafast transient absorption spectra
Authors: van Stokkum Ivo H. M. , Jumper Chanelle C. , Snellenburg Joris J. , Scholes Gregory D. , van Grondelle Rienk , Malý Pavel
Published: November 2016

When exciting a complex molecular system with a short optical pulse, all chromophores present in the system can be excited. The resulting superposition of electronically and vibrationally excited states evolves in time, which is monitored with transient absorption spectroscopy. We present a methodology to resolve simultaneously the contributions of the different electronically and vibrationally excited states from the complete data. The evolution of the excited states is described with a superposition of damped oscillations. The amplitude of a damped oscillation cos(ωnt)exp(−γnt) as a function of the detection wavelength constitutes a damped oscillation associated spectrum DOASn(λ) with an accompanying phase characteristic φn(λ). In a case study, the cryptophyte photosynthetic antenna complex PC612 which contains eight bilin chromophores was excited by a broadband optical pulse. Difference absorption spectra from 525 to 715 nm were measured until 1 ns. The population dynamics is described by four lifetimes, with interchromophore equilibration in 0.8 and 7.5 ps. We have resolved 24 DOAS with frequencies between 130 and 1649 cm−1 and with damping rates between 0.9 and 12 ps−1. In addition, 11 more DOAS with faster damping rates were necessary to describe the “coherent artefact.” The DOAS contains both ground and excited state features. Their interpretation is aided by DOAS analysis of simulated transient absorption signals resulting from stimulated emission and ground state bleach.
Ab initio effective rotational and rovibrational Hamiltonians for non-rigid systems via curvilinear second order vibrational Møller–Plesset perturbation theory
Authors: Changala P. Bryan , Baraban Joshua H.
Published: November 2016

We present a perturbative method for ab initio calculations of rotational and rovibrational effective Hamiltonians of both rigid and non-rigid molecules. Our approach is based on a curvilinear implementation of second order vibrational Møller-Plesset perturbation theory extended to include rotational effects via a second order contact transformation. Though more expensive, this approach is significantly more accurate than standard second order vibrational perturbation theory for systems that are poorly described to zeroth order by rectilinear normal mode harmonic oscillators. We apply this method to and demonstrate its accuracy on two molecules: Si2C, a quasilinear triatomic with significant bending anharmonicity, and CH3NO2, which contains a completely unhindered methyl rotor. In addition to these two examples, we discuss several key technical aspects of the method, including an efficient implementation of Eckart and quasi-Eckart frame embedding that does not rely on numerical finite differences.
Energy anisotropy as a function of the direction of spin magnetization for a doublet system
Authors: Cherry Peter J. , Malkin Vladimir G. , Malkina Olga L. , Asher James R.
Published: November 2016

This manuscript describes new phenomena that currently are not taken into account in both experimental EPR spectra interpretations and quantum chemical calculations of EPR parameters. This article presents an argument, with evidence, against the common belief that in the absence of an external magnetic field the total energy of a doublet system is independent of the spin orientation. Consequences of this phenomenon for interpretation of EPR experimental studies as well as for quantum chemical calculations of EPR parameters are discussed.
Three-dimensional fundamental thermo-elastic solutions applied to contact problems
Authors: Wang Z. P. , Wang T. , Li P. D. , Li X. Y. , Chen W. Q. , Müller R.
Published: November 2016

This paper aims to develop three-dimensional fundamental thermo-elastic solutions for an infinite/half-infinite space of a two-dimensional hexagonal quasi-crystal, which is subjected to a point heat source. Starting from the newly developed general solution in terms of quasi-harmonic potential functions, the corresponding fundamental solutions are derived by means of the trial-and-error technique. Six appropriate potential functions involved in the general solution are observed. The present fundamental solutions are applied to construct boundary integral equations governing the contact problems. Numerical calculations are performed to show the distributions of the thermo-elastic coupling field variables in a half-space subjected to a point thermal source.
Theoretical investigation of the phonon-limited carrier mobility in (001) Si films
Authors: Li Jing , Lampin Evelyne , Delerue Christophe , Niquet Yann-Michel
Published: November 2016

We calculate the phonon-limited carrier mobility in (001) Si films with a fully atomistic framework based on a tight-binding (TB) model for the electronic structure, a valence-force-field model for the phonons, and the Boltzmann transport equation. This framework reproduces the electron and phonon bands over the whole first Brillouin zone and accounts for all possible carrier-phonon scattering processes. It can also handle one-dimensional (wires) and three-dimensional (bulk) structures and therefore provides a consistent description of the effects of dimensionality on the phonon-limited mobilities. We first discuss the dependence of the electron and hole mobilities on the film thickness and carrier density. The mobility tends to decrease with decreasing film thickness and increasing carrier density, as the structural and electric confinement enhances the electron-phonon interactions. We then compare hydrogen-passivated and oxidized films in order to understand the impact of surface passivation on the mobility and discuss the transition from nanowires to films and bulk. Finally, we compare the semi-classical TB mobilities with quantum Non-Equilibrium Green's Function calculations based on k ⋅ p band structures and on deformation potentials for the electron-phonon interactions (KP-NEGF). The TB mobilities show a stronger dependence on carrier density than the KP-NEGF mobilities, yet weaker than the experimental data on Fully Depleted-Silicon-on-Insulator devices. We discuss the implications of these results on the nature of the apparent increase of the electron-phonon deformation potentials in silicon thin films.
Turbulence modulation by micro-particles in smooth and rough channels
Authors: De Marchis M. , Milici B.
Published: November 2016

Inertial micro-particles, dispersed in turbulent flows, are affected by the local dynamics of the carrier flow field. The presence of a relative dilute loading of particles entails some relevant changes in the mean velocity field. Moreover, the roughness of the solid boundary affects both the carrier and the carried phase dynamics and their mutual interaction. The underlying physics has been exhaustively tackled in the so-called one-way coupling regime, i.e., negligible action of particles onto the fluid, whereas many aspects of the particle back-reaction have been much less investigated and are still poorly understood. Thus the research in this area remains very active. In order to understand the mutual interaction between carrier and carried phases, direct numerical simulations are particularly suitable, even at low Reynolds number. Here, particle laden flow over a complex domain is investigated at friction Reynolds number Reτ = 180. The numerical analysis is based on the Euler-Lagrange approach, taking into account the fluid-particle interaction (two-way coupling). Point forces are used to represent the back-effect of particles on the turbulence and the effect of the wall’s roughness is taken into account modeling the elastic rebound of particles onto it, instead of using a virtual rebound model. The interest is focused on the effect of micro-particles of different inertia on fluid and particle statistics in the near-wall region. In particular, turbulent and solid phase statistics are compared with those obtained for a one-way coupled flow, for the same Reynolds number in smooth and rough channel flow configurations.
Safe and simple detection of sparse hydrogen by Pd-Au alloy/air based 1D photonic crystal sensor
Authors: Mitra S. , Biswas T. , Chattopadhyay R. , Ghosh J. , Bysakh S. , Bhadra S. K.
Published: November 2016

A simple integrated hydrogen sensor using Pd-Au alloy/air based one dimensional photonic crystal with an air defect layer is theoretically modeled. Structural parameters of the photonic crystal are delicately scaled to generate photonic band gap frequencies in a visible spectral regime. An optimized defect thickness permits a localized defect mode operating at a frequency within the photonic band gap region. Hydrogen absorption causes modification in the band gap characteristics due to variation of refractive index and lattice parameters of the alloy. As a result, the transmission peak appeared due to the resonant defect state gets shifted. This peak shifting is utilized to detect sparse amount of hydrogen present in the surrounding environment. A theoretical framework is built to calculate the refractive index profile of hydrogen loaded alloy using density functional theory and Bruggeman's effective medium approximation. The calculated refractive index variation of Pd3Au alloy film due to hydrogen loading is verified experimentally by measuring the reflectance characteristics. Lattice expansion properties of the alloy are studied through X-ray diffraction analyses. The proposed structure shows about 3 nm red shift of the transmission peak for a rise of 1% atomic hydrogen concentration in the alloy.
Modeling of dynamic mechanical properties of polymer composites reinforced by one dimensional nanofillers
Authors: Yu Y. , Lu M. , Chen M. H. , Wang L. S. , Bu Z. X. , Song G. , Sun L.
Published: November 2016

Owing to their high aspect ratio, large specific surface area, high axial Young's modulus/strength, and low density, one dimensional carbon nanomaterials can introduce significant change to the mechanical properties of polymer matrices, both static and dynamic. Thus, one of the most important potential applications of carbon nanotubes or nanofibers is to utilize the enhanced dynamic damping properties of polymer nanocomposites for improved vibration, acoustic, and fatigue performances. This study focuses on calculating the nanocomposite energy dissipation under dynamic mechanical loading. A micromechanical model based on quasi-static stick-slip analysis has been developed to quantify the dynamic mechanical properties of the nanocomposites as a function of external strain in the elastic region. Storage and loss moduli are used to characterize such dynamic mechanical behaviors. Influences of nanotube bundling and nanotube alignment on the damping property of composites have been quantified. Simulation results are in good agreement with the reported experimental measurements.
Plasmonic ladder–like structure and graphene assisted high surface enhanced Raman scattering detection
Authors: Mandal P. , Mondal Samir , Behera Gangadhar , Sharma Sudesh , Parmar K. P. S.
Published: November 2016

Surface enhanced Raman scattering (SERS) study is an interesting active area of research, where periodically patterned plasmonic substrates play a key role in SERS enhancement. Surface plasmon resonance excitation generates tremendous electromagnetic near-fields (E) in the form of localized or propagating near-fields contributing to the Raman signal (E4 process) to a great extent and overall enhancement is reported to be as high as 1010 or even more. Independently, graphene alone can enhance the Raman signal due to chemical enhancement. In the present study, we have attempted to achieve high SERS from the R6G Raman active probe using plasmonic patterned substrates in the presence and absence of graphene oxide. Plasmonic ladder-like patterned substrates are fabricated using laser interference lithography, which is cost effective, simple to operate, and has potential for large scale nanofabrication. By combining graphene oxide with R6G, we have found additional two time enhancement compared to that obtain from R6G alone on the plasmonic patterned substrate. Further, we have also attempted to understand the underlying mechanism to correlate the uniform and reproducible SERS through Raman mapping and Finite difference time domain computation. Our finding can potentially be applied for SERS investigation at a low molecular concentration.
Design, analysis, and testing of kinematic mount for astronomical observation instrument used in space camera
Authors: An Mingxin , Zhang Lihao , Xu Shuyan , Dong Jihong
Published: November 2016

A statically determinate kinematic mount structure is designed for an astronomical observation instrument. The basic principle of the proposed kinematic mount is introduced in detail, including the design principle, its structure, and its degrees of freedom. The compliance equations for the single-axis right circle flexure hinge are deduced, and mathematical models of the compliances of the bipod in the X-axis and Z-axis directions are established. Based on the index requirements, the range of one design parameter (the hinge groove depth, R) for the kinematic mount is determined. Parametric design is performed, with the entire structure being the design object and the first three eigenfrequencies as the design objective; the final design parameter for the kinematic mount is 1.9 mm. The first three eigenfrequencies of the final structure are 36.49 Hz, 38.65 Hz, and 72.41 Hz, which meet the frequency requirements. The Z-direction deformation and the bipod compliances in the X-axis and Z-axis directions are analyzed through simulations and experiments. The results show that (1) the Z-direction deformation of the bipod meets the displacement requirement; (2) the deviations between the finite element results and the compliance equation Cx results, and between the finite element results and the compliance equation Cz results are 8.8% and 3.92%, respectively; (3) the deviation between the experimental results and the compliance equation Cz results is 10.3%. It is concluded that the bipod compliance equations in the X-axis and Z-axis directions are valid, and that the kinematic mount thus meets the design requirements.
Fine-tuning the metallic core-shell nanostructures for plasmonic perovskite solar cells
Authors: Tang Mingyao , Zhou Lin , Gu Shuai , Zhu Weidong , Wang Yang , Xu Jun , Deng Zhengtao , Yu Tao , Lu Zhenda , Zhu Jia
Published: November 2016

Plasmonic nanostructures have been widely applied in various types of solar cells for improving light absorption and therefore energy conversion efficiency. In this work, we demonstrate that Au@SiO2 core-shell nanorods with finely tuned aspect ratios are highly beneficial for the CH3NH3PbI3 perovskite solar cell, with the simultaneous enhancement of solar absorption and external quantum efficiency across a broad range of wavelength, which can contribute to the increased cross-sectional scattering and spectrally absorbing energy density. Therefore, a 16.1% improvement (from 12.4% to 14.4%) of the maximal external quantum efficiency can be achieved by such structures, accompanied with a 13.5% improvement (from 20.0 to 22.7 mA/cm2) of the maximal short-circuit current density and little improvement of the open-circuit voltage and fill factor. Our findings also provide a general guideline to design solar cell structures with thinner absorber layers and improve the absorption in other poorly light-absorbing devices like lead free perovskite solar cells as well.
Solution-processed high-k magnesium oxide dielectrics for low-voltage oxide thin-film transistors
Authors: Jiang Guixia , Liu Ao , Liu Guoxia , Zhu Chundan , Meng You , Shin Byoungchul , Fortunato Elvira , Martins Rodrigo , Shan Fukai
Published: November 2016

Solution-processed metal-oxide thin films with high dielectric constants (k) have been extensively studied for low-cost and high-performance thin-film transistors (TFTs). In this report, MgO dielectric films were fabricated using the spin-coating method. The MgO dielectric films annealed at various temperatures (300, 400, 500, and 600 °C) were characterized by using thermogravimetric analysis, optical spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and atomic-force microscopy. The electrical measurements indicate that the insulating properties of MgO thin films are improved with an increase in annealing temperature. In order to clarify the potential application of MgO thin films as gate dielectrics in TFTs, solution-derived In2O3 channel layers were separately fabricated on various MgO dielectric layers. The optimized In2O3/MgO TFT exhibited an electron mobility of 5.48 cm2/V s, an on/off current ratio of 107, and a subthreshold swing of 0.33 V/dec at a low operation voltage of 6 V. This work represents a great step toward the development of portable and low-power consumption electronics.
Low power NiN-based resistive switching memory device using Ti doping
Authors: Jeon Dong Su , Park Ju Hyun , Kim Myung Ju , Kim Tae Geun
Published: November 2016

In this study, we investigated the properties of Ti-doped NiN-based resistive switching random access memories (ReRAMs) in comparison with both Al-doped and conventional NiN-based samples. The Ti dopants form metallic TiN particles in the nitride film, which induce local electric fields during the forming process causing filaments to form close to the TiN clusters. The TiN components in the filaments reduce the current level for the high resistive switching state (HRS) and low resistive switching state (LRS). In our testing, the Ti-doped sample had a current of 10 nA in the HRS and 23 μA in the LRS with a high on/off ratio (>103). This implies that the Ti doping effect enabled the sample to operate at low power. Furthermore, the Ti-doped samples also exhibited highly uniform operating parameters. In terms of reliability, the retention was measured to be >106 s at 85 °C, and the endurance was found to be at least 107 cycles. These results indicate that Ti-doped NiN-based ReRAM devices have significant advantages over other approaches for future nonvolatile memory devices.
Performance of planar heterojunction perovskite solar cells under light concentration
Authors: Alnuaimi Aaesha , Almansouri Ibraheem , Nayfeh Ammar
Published: November 2016

In this work, we present 2D simulation of planar heterojunction perovskite solar cells under high concentration using physics-based TCAD. The performance of planar perovskite heterojunction solar cells is examined up to 1000 suns. We analyze the effect of HTM mobility and band structure, surface recombination velocities at interfaces and the effect of series resistance under concentrated light. The simulation results revealed that the low mobility of HTM material limits the improvement in power conversation efficiency of perovskite solar cells under concentration. In addition, large band offset at perovskite/HTM interface contributes to the high series resistance. Moreover, losses due to high surface recombination at interfaces and the high series resistance deteriorate significantly the performance of perovskite solar cells under concentration.
Full-angle negative reflection realized by a gradient acoustic metasurface
Authors: Liu Bingyi , Zhao Wenyu , Jiang Yongyuan
Published: November 2016

We theoretically demonstrate that full-angle negative reflection can be realized by the gradient acoustic metasurface with a specific surface phase gradient value. A straightforward physical picture is presented here to understand such anomalous phenomena by considering the influence of the non-local effect that originates from the supercell periodicity on the gradient metasurface. Basing on the generalized law of reflection which is modified by a reciprocal lattice vector term, the negative reflection that beyond the critical angle is possible. In this paper, we utilize the coiling-up space structures of deep subwavelength geometrical scale to construct the desired gradient acoustic metasurface and observe the apparent full-angle negative reflection phenomenon. The present work enriches the content of the generalized law of reflection and provide new design methodology for functional acoustic wave modulation devices, such like directional ground acoustic cloaking and acoustic isolation devices.
Profile of 1 year of fieldwork experiences for undergraduate occupational therapy students from a large regional Australian university
Authors: Mackenzie Lynette , O'Toole Gjyn
Published: November 2016

Objective Fieldwork experience is a significant component of many health professional education programs and affects future practice for graduates. The present study used self-reported student data to produce a profile of undergraduate student placement experiences. Methods Cross-sectional surveys exploring placement location, setting and client types, models of supervision, interventions and financial costs were completed by students following each placement. Data were analysed using descriptive analysis. Results Placements were predominantly conducted outside capital cities (69.8%; n = 184), with 25.8% (n = 68) in rural settings. Students experienced predominantly public health in-patient settings and community settings, with only 15% experiencing private settings. Conclusions The placement profile of undergraduate occupational therapy students appeared to be consistent with workforce reports on occupational therapy professional practice. What is known about the topic? Fieldwork experienced by health professional students is critical to preparing new graduates for practice. Although the World Federation of Occupational Therapy provides guidance on what is required for occupational therapy fieldwork experience, little is known about what students actually experience during their fieldwork placements. What does this paper add? The present study is the first to document the range of fieldwork experienced by occupational therapy students in one program over 1 year, and provides the basis for comparison with other occupational therapy programs, as well as other disciplines nationally and internationally. What are the implications for practitioners? Occupational therapy students experienced few opportunities in private practice or speciality services, and had mostly one-on-one supervision. To provide a future workforce that is able to address the changing health system, it is vital that students are exposed to a range of fieldwork experiences and supervision styles that replicate the demands of future practice.
Coordination Behaviour of 1-(4,2′:6′,4′′-terpyridin-4′-yl)ferrocene and 1-(3,2′:6′,3′′-terpyridin-4′-yl)ferrocene: Predictable and Unpredictable Assembly Algorithms
Authors: Klein Y. Maximilian , Prescimone Alessandro , Constable Edwin C. , Housecroft Catherine E.
Published: November 2016

The reaction of 1-(4,2′:6′,4″-terpyridin-4′-yl)ferrocene (2) with ZnI2 leads to [{ZnI2(2)}4·1.4MeOH·0.8H2O] which contains a discrete [4+4] metallocycle. Crystal growth experiments demonstrate that reactions of 2 with Zn(OAc)2 or CuCl2 result in the formation of single- or double-stranded 1D polymer chains, respectively, the latter facilitated by the formation of {Cu2Cl4} dinuclear nodes. While both 2 and its isomer 1-(3,2′:6′,3″-terpyridin-4′-yl)ferrocene (3) present V-shaped donor sets, rotation about interannular bonds in 3 generates flexible vectorial properties associated with limiting convergent and divergent orientations of the nitrogen donors. The synthesis and characterisation of 3 are described as are reactions of 3 with ZnCl2 or ZnBr2 which lead, respectively, to a metallosquare in [{ZnCl2(3)}4·3CHCl3·3MeOH] or a helical polymer in [{ZnBr2(3)}·MeOH]n. The tight pitch of the helix in the latter (8.7879(9) Å) is controlled by a combination of the orientations of the N,N″-donor sets in 3, and intra-chain π-stacking interactions involving ferrocenyl and pyridine units.
Structural and functional consequences of a disease mutation in the telomere protein TPP1
Authors: Bisht Kamlesh , Smith Eric M. , Tesmer Valerie M. , Nandakumar Jayakrishnan
Published: November 2016

Significance

Telomerase is an enzyme that replicates chromosome ends to facilitate continued stem cell division. Mutations in telomerase or in telomerase-related genes result in stem cell-dysfunction diseases, such as dyskeratosis congenita (DC). Despite its devastating nature, DC currently has no cure. Here we report the crystal structure of a mutant protein implicated in DC to reveal how the mutation disrupts a region of the protein essential for telomerase function. Furthermore, we demonstrated that this mutation, when introduced into a human cell line, is sufficient to cause the cellular underpinnings of DC. Our results therefore make the strong prediction that correcting the mutation in the stem cells of the patient will reverse the cellular symptoms of disease.
Rapid and independent memory formation in the parietal cortex
Authors: Brodt Svenja , Pöhlchen Dorothee , Flanagin Virginia L. , Glasauer Stefan , Gais Steffen , Schönauer Monika
Published: November 2016

Significance

When it comes to memory, our brain needs to deal with two opposing demands: remaining plastic to acquire new information rapidly and maintaining old information faithfully over long periods. It is assumed that two distinct brain systems are in charge of these functions: the fast-learning hippocampus and the slow-learning neocortex. The interaction between these two systems has traditionally been seen as very slow, requiring weeks or months to build a neocortical memory trace. In this study, brain activity during virtual-reality navigation shows that contributions of hippocampus and parietal neocortex to memory are changing substantially already at the time a spatial memory representation is built. Notably, we show that the posterior parietal cortex fulfills all criteria for a hippocampus-independent memory representation.
Serotonin and arginine–vasopressin mediate sex differences in the regulation of dominance and aggression by the social brain
Authors: Terranova Joseph I. , Song Zhimin , Larkin Tony E. , Hardcastle Nathan , Norvelle Alisa , Riaz Ansa , Albers H. Elliott
Published: November 2016

Significance

There are profound sex differences in the expression of social behavior and in the incidence of many psychiatric disorders, and yet little is known about how the brain mechanisms underlying these phenomena differ in females and males. Here, we report that serotonin (5-HT) and arginine–vasopressin (AVP) act in opposite ways within the hypothalamus to regulate dominance and aggression in females and males. Dominance and aggression are promoted by 5-HT in females and by AVP in males. Because dominance and aggressiveness have been linked to the resistance to stress-related psychiatric disorders, these disorders may be more effectively treated with 5-HT–targeted drugs in females and AVP-targeted drugs in males.
Optimizing countershading camouflage
Authors: Cuthill Innes C. , Sanghera N. Simon , Penacchio Olivier , Lovell Paul George , Ruxton Graeme D. , Harris Julie M.
Published: November 2016

Significance

Because the sun and sky are above us, natural illumination is directional and the cues from shading reveal shape and depth. However, many animals are darker on their backs and, over 100 years ago, it was proposed that this phenomenon was camouflage: countering the cues to shape that directional illumination creates. However, does this camouflage work in practice? We predicted the optimal countershading for different lighting conditions and tested this possibility with correspondingly patterned model “caterpillars” predated by birds in the wild. Predation rates varied with coloration and lighting in exactly the manner predicted. Such subtlety in the effects of countershading vindicates conclusions from prior evidence demonstrating stronger countershading in animals in more brightly lit habitats.
S2 from equine infectious anemia virus is an infectivity factor which counteracts the retroviral inhibitors SERINC5 and SERINC3
Authors: Chande Ajit , Cuccurullo Emilia Cristiana , Rosa Annachiara , Ziglio Serena , Carpenter Susan , Pizzato Massimo
Published: November 2016

Significance

Serine incorporators (SERINC) 5 and 3 are recently discovered cellular inhibitors of retroviruses, which are incorporated into virus particles and impair their ability to propagate the infection to target cells. Only two groups of viruses (represented by HIV-1 and murine leukemia virus) had been identified as having evolved the ability to counteract SERINC inhibition. We found that equine infectious anemia virus, which causes a debilitating disease in horses, also has acquired the capacity to protect the virus particle from inhibition by SERINC5 and SERINC3 by using its small protein S2. That three different retroviruses have independently evolved the ability to elude inhibition by SERINC5 and SERINC3 indicates that these cellular factors play a fundamental role against various retrovirus pathogens.
HIF-KDM3A-MMP12 regulatory circuit ensures trophoblast plasticity and placental adaptations to hypoxia
Authors: Chakraborty Damayanti , Cui Wei , Rosario Gracy X. , Scott Regan L. , Dhakal Pramod , Renaud Stephen J. , Tachibana Makoto , Rumi M. A. Karim , Mason Clifford W. , Krieg Adam J. , Soares Michael J.
Published: November 2016

Significance

The hemochorial placenta is a dynamic structure endowed with responsibilities controlling the extraction of maternal resources, ensuring fetal development and preserving maternal health. A healthy placenta exhibits plasticity and can adapt to environmental challenges. Such adaptations can be executed through instructive actions on trophoblast stem cells, influencing their abilities to expand and differentiate into specialized cells that accommodate the challenge. Hypoxia, when appropriately timed, promotes invasive trophoblast-directed uterine spiral artery remodeling. Hypoxia activates hypoxia inducible factor-dependent expression of lysine demethylase 3A, modifying the histone landscape on key target genes, including matrix metallopeptidase 12, which acts to facilitate trophoblast invasion and uterine vascular remodeling. Plasticity and adaptations at the maternal–fetal interface safeguard placental development and the healthy progression of pregnancy.
Selvamicin, an atypical antifungal polyene from two alternative genomic contexts
Authors: Van Arnam Ethan B. , Ruzzini Antonio C. , Sit Clarissa S. , Horn Heidi , Pinto-Tomás Adrián A. , Currie Cameron R. , Clardy Jon
Published: November 2016

Significance

Bacteria use small molecules to mediate their relationships with nearby microbes, and these molecules represent both a promising source of therapeutic agents and a model system for the evolution and dissemination of molecular diversity. This study deals with one such molecule, selvamicin, which is produced by ant-associated bacteria. These bacteria protect the ants’ nests against fungal pathogens. Selvamicin is an atypical member of a clinically important class of antifungal agents, and it appears to have both better therapeutic properties and a different mechanism of action. Further, the genes for producing it are found on the bacteria’s chromosome in one ant nest but on a plasmid in another, illustrating the likely path by which it has spread.
Effect of electron count and chemical complexity in the Ta-Nb-Hf-Zr-Ti high-entropy alloy superconductor
Authors: von Rohr Fabian , Winiarski Michał J. , Tao Jing , Klimczuk Tomasz , Cava Robert Joseph
Published: November 2016

Significance

High-entropy alloys are a new class of materials that consist of several principal elements arranged on simple lattices. These structures are stabilized by the high configurational entropy of the random mixing of the elements. Here, we show that the properties of a superconducting high-entropy alloy are strongly related to the electron count and that the superconducting transition temperatures of these alloys fall between those of analogous crystalline and amorphous materials. We find that despite the large degree of randomness and disorder in these alloys, the superconducting properties are nevertheless strongly dependent on the chemical composition and complexity. We argue that high-entropy alloys are excellent model systems for understanding how superconductivity and other collective quantum states evolve from crystals to amorphous solids.
The Nagorno-Karabakh conflict in the context of South Caucasus regional security issues: An Armenian perspective†
Authors: Minasyan Sergey
Published: November 2016

For more than a quarter-century, the Nagorno-Karabakh conflict has been one of the most important factors influencing the political map of the South Caucasus. On 12 May 1994, Nagorno-Karabakh, Armenia, and Azerbaijan signed a cease-fire agreement that ended military operations in the conflict zone and has been observed until recently. Negotiations for a peaceful settlement have been underway within the framework of the Organization for Security and Co-operation in Europe Minsk Group co-chaired by the USA, Russia, and France since 1992, but society and the elite in Armenia, Nagorno-Karabakh, and Azerbaijan remain largely unprepared for compromise. Considering the settlement process a zero-sum game, they have generally accused one another of escalating the conflict and of a lack of willingness to restore peace. Other countries and international organizations involved in the negotiations do not share a vision of the future and frequently pursue their own interests. Accordingly, the Karabakh conflict could remain unresolved for decades more. The aim of the paper is a general assessment of the current stage and dynamic of this conflict and the impact of new trends and old obstacles on the prospects for further settlement.
Comparative Use of Shallow and Deepwater Habitats by Juvenile Pacific Salmon in the Columbia River Estuary Prior to Ocean Entry
Authors: Roegner G. Curtis , Weitkamp Laurie A. , Teel David J.
Published: November 2016

The degree to which fine-scale habitat use by salmonid species and stocks varies within habitat types such as estuaries is not fully resolved. We sampled shallow shoreline and deeper main-stem channel habitats in the Columbia River estuary over 3 years to compare salmon species composition, migration timing, density, size, and production type (hatchery or natural). Results indicated a high degree of spatial heterogeneity in habitat occupancy by the five salmonid species that are native to the basin. Salmonid communities at two channel habitat sites were much more similar to each other than to the community at a shoreline site. Salmonids sampled at the shoreline site were primarily subyearling Chinook Salmon Oncorhynchus tshawytscha and Chum Salmon O. keta and yearling Coho Salmon O. kisutch, with few other salmonids present. In contrast, channel habitat contained a higher diversity of salmon species, with samples representing all species of anadromous salmonids, including Sockeye Salmon O. nerka and steelhead O. mykiss. Salmonids in deeper channel habitat were generally larger than salmonids found along the shore, and the proportion of hatchery-origin salmon was also higher in deep channel habitats. On a per-area basis, we also found much higher densities of salmon along the shoreline than in channel habitats. For Chinook Salmon, habitat use also differed by genetic stock of origin: upper-river stocks primarily used deeper channels, while lower-river populations used both channel and shoreline areas. We concluded that sampling at both habitat types is required to fully encompass the migration patterns of all salmon evolutionarily significant units in the Columbia River basin. These spatial and temporal variations in salmon timing and density have ramifications for feeding, growth, and competitive interactions. This study provides information that is relevant for conservation efforts targeting specific fish populations and efforts to evaluate the potential impacts of in-water activities in the Columbia River estuary.

Received May 12, 2016; accepted August 19, 2016
Dynamics of resonant magnetic field penetration and plasma rotation
Authors: Ivanov N.V. , Kakurin A.M.
Published: November 2016

Results of calculations and analysis of the penetration of resonant magnetic perturbations (RMP) into tokamak plasma are presented. The TEAR code used for the calculations is based on a two-fluid magnetohydrodynamics approximation that gives coupled diffusion-type equations for the magnetic flux perturbation and for plasma rotation velocities in toroidal and poloidal directions. The radial distribution of the magnetic flux perturbation is calculated taking account of an externally applied RMP and magnetic perturbation generated by an eddy current in the resistive-vacuum vessel. The decoupling of magnetic-island velocity from the velocity of plasma rotation is employed in the calculations according to available experimental evidence and corresponding theoretical understanding. The account of this decoupling, as well as of plasma rotation in the poloidal direction in addition to the toroidal one, reduces the RMP penetration threshold and accelerates the penetration process. The main attention is paid to the dependences of the RMP penetration dynamics on the simulation conditions. The simulation findings are compared with available experimental data. Some predictions of the penetration threshold values for ITER conditions are presented.
The monotonicity and convexity for the ratios of modified Bessel functions of the second kind and applications
Authors: Yang Zhen-Hang , Zheng Shen-Zhou
Published: November 2016

Let

K

v

(
x
)

K_{v}\left ( x\right )

be the modified Bessel functions of the second kind of order

v
v

. We prove that the function
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="x right-arrow from bar upper K Subscript u Baseline left-parenthesis x right-parenthesis upper K Subscript v Baseline left-parenthesis x right-parenthesis slash upper K Subscript left-parenthesis u plus v right-parenthesis slash 2 Baseline left-parenthesis x right-parenthesis squared">

x
↦

K

u

(
x
)

K

v

(
x
)

/

K

(
u
+
v
)

/

2

(
x
)

2

x\mapsto K_{u}\left ( x\right ) K_{v}\left ( x\right ) /K_{\left ( u+v\right ) /2}\left ( x\right ) ^{2}

is strictly decreasing on

(
0
,
∞
)

\left ( 0,\infty \right )

. Our study not only involves the Turán type inequalities, log-convexity or log-concavity of

K

v

(
x
)

K_{v}\left ( x\right )

, and the conjecture posed by Baricz, but also yields various new results concerning the monotonicity and convexity of the ratios of the modified Bessel functions of the second kind. As applications of our main theorems, some new sharp inequalities involving

K

v

(
x
)

K_{v}\left ( x\right )

are presented, which contain sharp estimates for

K

v

(
x
)

K_{v}\left ( x\right )

and sharp bounds for the ratios

K

v

′

(
x
)

/

K

v

(
x
)

K_{v}^{\prime }\left ( x\right ) /K_{v}\left ( x\right )

and

K

v
+
1

(
x
)

/

K

v

(
x
)

K_{v+1}\left ( x\right ) /K_{v}\left ( x\right )

.
Characterizations of blocks by Loewy lengths of their centers
Authors: Otokita Yoshihiro
Published: November 2016

We study a block

B
B

of a finite group with respect to an algebraically closed field of prime characteristic through the Loewy length

ll

Z

B

\textrm {ll}{\textbf {Z}B}

of the center

Z

B

\textbf {Z}B

. In this paper, we give some upper bounds for

ll

Z

B

\textrm {ll}{\textbf {Z}B}

in terms of characters, subsections and defect groups associated to

B
B

. As a corollary to these results, we characterize some blocks by

ll

Z

B

\textrm {ll}{\textbf {Z}B}

.
Degree bound for separating invariants of abelian groups
Authors: Domokos M.
Published: November 2016

It is proved that the universal degree bound for separating polynomial invariants of a finite abelian group (in non-modular characteristic) is typically strictly smaller than the universal degree bound for generators of polynomial invariants. More precisely, these degree bounds can be equal only if the group is cyclic or is the direct sum ofrreven order cyclic groups where the number of two-element direct summands is not less than the integer part of the half ofrr. A characterization of separating sets of monomials is given in terms of zero-sum sequences over abelian groups.
Finite presentability and isomorphism of Cayley graphs of monoids
Authors: Awang J. , Pfeiffer M. , Ruškuc N.
Published: November 2016

Two finitely generated monoids are constructed, one finitely presented, the other not, whose (directed, unlabelled) Cayley graphs are isomorphic.
Agent-based modeling: case study in cleavage furrow models
Authors: Mogilner Alex , Manhart Angelika
Published: November 2016

The number of studies in cell biology in which quantitative models accompany experiments has been growing steadily. Roughly, mathematical and computational techniques of these models can be classified as “differential equation based” (DE) or “agent based” (AB). Recently AB models have started to outnumber DE models, but understanding of AB philosophy and methodology is much less widespread than familiarity with DE techniques. Here we use the history of modeling a fundamental biological problem—positioning of the cleavage furrow in dividing cells—to explain how and why DE and AB models are used. We discuss differences, advantages, and shortcomings of these two approaches.
HMGB1 translocation and release mediate cigarette smoke–induced pulmonary inflammation in mice through a TLR4/MyD88-dependent signaling pathway
Authors: Cheng Yao , Wang Dan , Wang Bin , Li Huanan , Xiong Junjie , Xu Shuyun , Chen Quan , Tao Kun , Yang Xiaoyan , Zhu Yu , He Sirong
Published: November 2016

We performed studies to determine the role of high-mobility group box 1 (HMGB1) in cigarette smoke (CS)–induced pulmonary inflammation. After mice were exposed to five cigarettes four times a day for 3 d, toll-like receptor 4 (TLR4) expression and TLR4-mediated signaling were significantly up-regulated, and HMGB1 had translocated from the nucleus to the cytoplasm in lung epithelial cells and then been released into the extracellular lung space. On CS exposure, inflammatory cell recruitment and proinflammatory cytokine production were significantly increased in lung tissue and bronchoalveolar lavage, and these effects depended on the TLR4 signaling pathway. HMGB1 inhibition decreased the CS-induced inflammatory response, whereas treatment with exogenous HMGB1 aggravated the damage and increased the phosphorylation of JNK, p38, and IκBα in the lungs of wild-type mice but not in TLR4-knockout mice. Blockade of TLR4 action or TLR4 knockout significantly inhibited HMGB1-induced proinflammatory cytokine production in mouse tracheal epithelial (MTE) cells and lung tissues. In addition, a MyD88 deficiency inhibited JNK, p38, and IκBα phosphorylation, and this effect was associated with the suppressed production of TNF-α and IL-1β in MTE cells and lung tissues in response to CS stimulation. Thus HMGB1 activates the NF-κB and JNK/p38 pathways through TLR4/MyD88-dependent signaling and induces an inflammatory response in lungs exposed to CS.
The p150N domain of chromatin assembly factor-1 regulates Ki-67 accumulation on the mitotic perichromosomal layer
Authors: Matheson Timothy D. , Kaufman Paul D.
Published: November 2016

Chromatin assembly factor 1 (CAF-1) deposits histones during DNA synthesis. The p150 subunit of human CAF-1 contains an N-terminal domain (p150N) that is dispensable for histone deposition but promotes the localization of specific loci (nucleolar-associated domains [NADs]) and proteins to the nucleolus during interphase. One of the p150N-regulated proteins is proliferation antigen Ki-67, whose depletion also decreases the nucleolar association of NADs. Ki-67 is also a fundamental component of the perichromosomal layer (PCL), a sheath of proteins surrounding condensed chromosomes during mitosis. We show here that a subset of p150 localizes to the PCL during mitosis and that p150N is required for normal levels of Ki-67 accumulation on the PCL. This activity requires the sumoylation-interacting motif within p150N, which is also required for the nucleolar localization of NADs and Ki-67 during interphase. In this manner, p150N coordinates both interphase and mitotic nuclear structures via Ki67.
Influence of Neighbor Experience and Exit on Small Farmer Market Participation
Authors: Michelson Hope C.
Published: November 2016

This research analyzes the motivations and dynamics of small farmer participation in supermarket supply chains in developing countries: why some small farmers join these new markets and continue their participation; why others drop out or decline the relationship from the outset. Drawing on insights from the technology‐adoption literature on learning and experimentation, and also on findings from a simple two‐period Bayesian model of farmer decisions to participate in a new market, we incorporate measures of neighboring farmers’ experience into the decision model. Results suggest that farmers delay entry to observe their neighbors’ outcomes; we find a negative relationship between the number of neighbor participants in a given period and a farmer's own decision to enter the supply chain. We find evidence that farmers delay entry for strategic reasons, allowing neighbors to bear the costs associated with a first wave of adjustment to the market, including higher product rejection rates and lower initial annual transactions with supermarkets, compared to revenues from marketing in the traditional way. Results are robust to definitions of neighbors using both administrative and geographic designations. Our results raise questions about the optimal sequence and level of farmers' market participation and exit, which remain largely unexplored in the literature.
Effect of grain-scale gas patches on the seismic properties of double porosity rocks
Authors: Glubokovskikh Stanislav , Gurevich Boris
Published: November 2016

Time-lapse ultrasonic measurements constitute a tool to establish and calibrate rock physics models for surface seismic monitoring of partially saturated rocks. This workflow requires one to take into account seismic dispersion caused by frequency-dependent wave-induced fluid flow. We develop a theory of squirt flow in rocks saturated with a viscoelastic material containing isolated gas patches between compliant intergranular contacts. This model is valid for the entire frequency range, from seismic to ultrasonic. In the limit of full saturation the derived equations reduce to the Gassmann equations in the low-frequency regime and traditional squirt theory in the high-frequency regime. The model prediction of ultrasonic velocities versus saturation matches with experimental observations.
Metabolic cost of calcification in bivalve larvae under experimental ocean acidification
Authors: Frieder Christina A. , Applebaum Scott L. , Pan T.-C. Francis , Hedgecock Dennis , Manahan Donal T.
Published: November 2016

Physiological increases in energy expenditure frequently occur in response to environmental stress. Although energy limitation is often invoked as a basis for decreased calcification under ocean acidification, energy-relevant measurements related to this process are scant. In this study we focus on first-shell (prodissoconch I) formation in larvae of the Pacific oyster, Crassostrea gigas. The energy cost of calcification was empirically derived to be ≤ 1.1 µJ (ng CaCO3)−1. Regardless of the saturation state of aragonite (2.77 vs. 0.77), larvae utilize the same amount of total energy to complete first-shell formation. Even though there was a 56% reduction of shell mass and an increase in dissolution at aragonite undersaturation, first-shell formation is not energy limited because sufficient endogenous reserves are available to meet metabolic demand. Further studies were undertaken on larvae from genetic crosses of pedigreed lines to test for variance in response to aragonite undersaturation. Larval families show variation in response to ocean acidification, with loss of shell size ranging from no effect to 28%. These differences show that resilience to ocean acidification may exist among genotypes. Combined studies of bioenergetics and genetics are promising approaches for understanding climate change impacts on marine organisms that undergo calcification.