bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary experimental investigation of a complex dual-band high power microwave source
Authors: Zhang Xiaoping , Li Yangmei , Li Zhiqiang , Zhong Huihuang , Qian Baoliang
Published: October 2015

In order to promote the power conversion efficiency of a magnetically insulated transmission line oscillator (MILO) and obtain microwaves in dual bands, an axially extracted C-band virtual cathode oscillator (VCO) with multiple resonant cavities is introduced to partially utilize the load current of an S-band MILO. The formed novel dual-band high power microwave source called MILO and VCO is investigated with simulation and experimentally. A dual-band radiation antenna is designed to effectively radiate microwaves generated by the MILO and the VCO, respectively, while avoiding them being influenced by the microwave reflection and diffraction. The preliminary experimental results measured by the dual-band diagnostic system show that both the MILO and the VCO operate normally under repeated shots. A microwave of 2.1 GHz, 1.70 GW is generated from the MILO and a 0.37 GW microwave at frequencies of 4.1 GHz and 3.8 GHz is generated from the VCO under the condition of about 440 kV and 35 kA. Compared with a single MILO (10.6%), a MILO and VCO achieves higher total power and efficiency (13.4%) in both S and C bands, indicating that the load current of the MILO partially couples into the beam-wave interaction in the VCO and then contributes to the output microwaves. However, more works are needed regarding the spectrum purification of the VCO and promotion of the output power of both the MILO and the VCO.
Multiple scattering of metallic wire structures
Authors: Zhan T. R. , Chui S. T. , Lin Z. F.
Published: October 2015

We describe how the electromagnetic resonance and scattering properties of complex structures of which metallic wire structures are constituents can be studied with multiple scattering theory. The t matrix of individual structures is calculated with our recently developed rigorous equivalent circuit theory in which retardation effects are taken into account. We illustrate our method with the example of a planar periodic array of split ring resonators. The transmission is calculated as a function of frequency. The result is found to agree well with that obtained by a commercial code (COMSOL) but our result is two orders of magnitude faster and requires much less memory.
On the stability of a quasicrystal and its crystalline approximant in a system of hard disks with a soft corona
Authors: Pattabhiraman Harini , Gantapara Anjan P. , Dijkstra Marjolein
Published: October 2015

Using computer simulations, we study the phase behavior of a model system of colloidal hard disks with a diameter σ and a soft corona of width 1.4σ. The particles interact with a hard core and a repulsive square-shoulder potential. We calculate the free energy of the random-tiling quasicrystal and its crystalline approximants using the Frenkel-Ladd method. We explicitly account for the configurational entropy associated with the number of distinct configurations of the random-tiling quasicrystal. We map out the phase diagram and find that the random tiling dodecagonal quasicrystal is stabilised by entropy at finite temperatures with respect to the crystalline approximants that we considered, and its stability region seems to extend to zero temperature as the energies of the defect-free quasicrystal and the crystalline approximants are equal within our statistical accuracy.
Beam simulation studies of ECR beam extraction and low energy beam transport for FRIB
Authors: Ren Haitao , Pozdeyev Eduard , Lund Steven M. , Machicoane Guillaume , Wu Xiaoyu , Morgan Glenn
Published: October 2015

To meet the beam power requirements of 400 kW at the fragmentation target for facility for Rare Isotope Beams (FRIB), simultaneous acceleration of two-charge states should be used for heavier ions. These intense multi-charged ion beams will be produced by a 28 GHz electron cyclotron resonance (ECR) ion source at a high voltage of 35 kV. After extraction, the ion beam will be pre-accelerated to 12 keV/u with a 50 kV platform, transported down to an achromatic charge state selection (CSS) system followed by a vertical transport line, and then injected into a radio frequency quadrupole accelerator. The TRACK code developed at ANL is used to perform the simulations of the ECR beam extraction and low energy beam transport for FRIB. In this study, we include the magnetic field of ECR ion source into simulations. Different initial beam conditions as well as different space charge neutralization levels are tested for the ECR beamline. The beam loss in CSS system and the corresponding protective measures are discussed. The detailed results about the beam dynamic simulation and beam loss in CSS system will be presented in this paper.
A computational study of turbulent kinetic energy transport in barotropic turbulence on the f-plane
Authors: Grooms Ian
Published: October 2015

Energy transport by eddies is diagnosed from a series of simulations of stochastically forced, inhomogeneous two-dimensional turbulence—barotropic dynamics on the f-plane. The divergence of the energy flux is compared to diffusive models, both fractional and harmonic, and the inferred diffusivity κ is compared to a mixing-length model κ ∝ Vℓ where V and ℓ are eddy velocity and length scales, respectively. The flux-divergence is found to be well approximated by Laplacian diffusion with a mixing-length approximation. This study provides some support for diffusive modeling of mesoscale eddy energy transport in ocean model parameterizations.
Phase-selective vanadium dioxide (VO2) nanostructured thin films by pulsed laser deposition
Authors: Masina B. N. , Lafane S. , Wu L. , Akande A. A. , Mwakikunga B. , Abdelli-Messaci S. , Kerdja T. , Forbes A.
Published: October 2015

Thin films of monoclinic nanostructured vanadium dioxide are notoriously difficult to produce in a selective manner. To date, post-annealing, after pulsed laser deposition (PLD), has been used to revert the crystal phase or to remove impurities, and non-glass substrates have been employed, thus reducing the efficacy of the transparency switching. Here, we overcome these limitations in PLD by optimizing a laser-ablation and deposition process through optical imaging of the laser-induced plasma. We report high quality monoclinic rutile-type vanadium dioxide (VO2) (M1) nanoparticles without post-annealing, and on a glass substrate. Our samples demonstrate a reversible metal-to-insulator transition at ∼43 °C, without any doping, paving the way to switchable transparency in optical materials at room temperature.
Imaginary time density-density correlations for two-dimensional electron gases at high density
Authors: Motta M. , Galli D. E. , Moroni S. , Vitali E.
Published: October 2015

We evaluate imaginary time density-density correlation functions for two-dimensional homogeneous electron gases of up to 42 particles in the continuum using the phaseless auxiliary field quantum Monte Carlo method. We use periodic boundary conditions and up to 300 plane waves as basis set elements. We show that such methodology, once equipped with suitable numerical stabilization techniques necessary to deal with exponentials, products, and inversions of large matrices, gives access to the calculation of imaginary time correlation functions for medium-sized systems. We discuss the numerical stabilization techniques and the computational complexity of the methodology and we present the limitations related to the size of the systems on a quantitative basis. We perform the inverse Laplace transform of the obtained density-density correlation functions, assessing the ability of the phaseless auxiliary field quantum Monte Carlo method to evaluate dynamical properties of medium-sized homogeneous fermion systems.
Excellent performances of energy harvester using cantilever driving double-clamped 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 plates and symmetric middle-stops
Authors: Zeng Zhou , Ren Bo , Xu Qing , Lin Di , Di Wenning , Luo Haosu , Wang Dong
Published: October 2015

We present a high performance nonlinear piezoelectric energy harvester constituted by a cantilever with symmetrically middle-stops and double-clamped piezoelectric plates based on piezoelectric single crystal 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3. Electrical properties of the device under different excitation frequencies, accelerations, and load resistances are studied systematically. Under a low acceleration of 3 m/s2 (0.3 g), a peak voltage of 26.2 V and a maximum normalized power of 25.6 mW/g2 were obtained across a matching impedance of 600 kΩ with favorable bandwidths. The low excitation acceleration and excellent performances indicate that the device can be a promising candidate for energy harvesting in low-power electronics and wireless sensors.
Uniformity of spherical shock wave dynamically stabilized by two successive laser profiles in direct-drive inertial confinement fusion implosions
Authors: Temporal M. , Canaud B. , Garbett W. J. , Ramis R.
Published: October 2015

The implosion uniformity of a directly driven spherical inertial confinement fusion capsule is considered within the context of the Laser Mégajoule configuration. Two-dimensional (2D) hydrodynamic simulations have been performed assuming irradiation with two laser beam cones located at 49° and 131° with respect to the axis of symmetry. The laser energy deposition causes an inward shock wave whose surface is tracked in time, providing the time evolution of its non-uniformity. The illumination model has been used to optimize the laser intensity profiles used as input in the 2D hydro-calculations. It is found that a single stationary laser profile does not maintain a uniform shock front over time. To overcome this drawback, it is proposed to use two laser profiles acting successively in time, in order to dynamically stabilize the non-uniformity of the shock front.
Electrocaloric effect in core-shell ferroelectric ceramics: Theoretical approach and practical conclusions
Authors: Anoufa M. , Kiat J. M. , Bogicevic C.
Published: October 2015

Most of the theoretical and experimental studies on the electrocaloric effect (ECE) are devoted to thin films, but they can be hardly envisaged for cooling macroscopic systems; moreover, the results obtained cannot be easily transposed for larger systems like multilayered ceramics. Therefore, efforts should also be focused on predicting, synthesizing, and characterizing interesting bulk single crystal or ceramics. In ferroelectric nanoparticles and ceramics, the core-shell structure of grains is of uttermost importance to explain the experimental results at small sizes. Moreover, it can be used to tailor physical properties, such as energy storage, by experimenting with the composition, thickness, and permittivity of the shell. Here, we report the effect of such structures on the electrocaloric effects in a variety of ferroelectric materials. The magnitude of ECE as well as its field and temperature-dependence are obtained for different types of core-shells. The optimal configuration for a maximal ECE is deduced.
Utilizing multiple state variables to improve the dynamic range of analog switching in a memristor
Authors: Jeong YeonJoo , Kim Sungho , Lu Wei D.
Published: October 2015

Memristors and memristive systems have been extensively studied for data storage and computing applications such as neuromorphic systems. To act as synapses in neuromorphic systems, the memristor needs to exhibit analog resistive switching (RS) behavior with incremental conductance change. In this study, we show that the dynamic range of the analog RS behavior can be significantly enhanced in a tantalum-oxide-based memristor. By controlling different state variables enabled by different physical effects during the RS process, the gradual filament expansion stage can be selectively enhanced without strongly affecting the abrupt filament length growth stage. Detailed physics-based modeling further verified the observed experimental effects and revealed the roles of oxygen vacancy drift and diffusion processes, and how the diffusion process can be selectively enhanced during the filament expansion stage. These findings lead to more desirable and reliable memristor behaviors for analog computing applications. Additionally, the ability to selectively control different internal physical processes demonstrated in the current study provides guidance for continued device optimization of memristor devices in general.
Capacitive type magnetoimpedance effect in piezoelectric-magnetostrictive composite resonator
Authors: Wang Wei , Wang Zhifeng , Luo Xiaobin , Tao Jin , Zhang Ning , Xu Xinran , Zhou Lisheng
Published: October 2015

In this article, a significant capacitive type magnetoimpedance effect of piezoelectric-magnetostrictive (PM) composite resonator is presented at room temperature. The variations of relatively effective permittivity of the PM resonator with a dc magnetic field are responsible for the capacitive type magnetoimpedance effect. About 225% and 50% of magnetoimpedance have been achieved at anti-resonance and resonance frequencies of the PM resonator, respectively, which reveals a stronger magnetoelectric coupling at the anti-resonance frequency than that at the resonance frequency of the PM resonator. A detailed analysis also indicates that the magnetocapacitance and magnetoinduction effects of the resonator were originated from the variations of relatively effective permittivity of the resonator. More than 200% and 170% of magnetocapacitance and magnetoinduction were achieved at room temperature in the anti-resonance window, respectively, and also about 150% and 60% of capacitance and induction modulation were observed in the resonance window by applying the dc magnetic fields. The capacitive type magnetoimpedance effect is expected to be used in the design of magnetic-field-tuned ultrasonic transducer.
Local conductance: A means to extract polarization and depolarizing fields near domain walls in ferroelectrics
Authors: Douglas A. M. , Kumar A. , Whatmore R. W. , Gregg J. M.
Published: October 2015

Conducting atomic force microscopy images of bulk semiconducting BaTiO3 surfaces show clear stripe domain contrast. High local conductance correlates with strong out-of-plane polarization (mapped independently using piezoresponse force microscopy), and current-voltage characteristics are consistent with dipole-induced alterations in Schottky barriers at the metallic tip-ferroelectric interface. Indeed, analyzing current-voltage data in terms of established Schottky barrier models allows relative variations in the surface polarization, and hence the local domain structure, to be determined. Fitting also reveals the signature of surface-related depolarizing fields concentrated near domain walls. Domain information obtained from mapping local conductance appears to be more surface-sensitive than that from piezoresponse force microscopy. In the right materials systems, local current mapping could therefore represent a useful complementary technique for evaluating polarization and local electric fields with nanoscale resolution.
Cytomegalovirus infection and pathogenesis in the human placenta
Authors: Pereira Lenore , Tabata Takako , Petitt Matthew
Published: October 2015

Human cytomegalovirus (HCMV) is the most common cause of congenital viral infection. Affected children can have permanent neurological complications, including hearing loss, visual impairment and mental retardation1–3. In Australia, 57% of women are seronegative and at risk for primary infection and transmission of virus to the fetus during pregnancy4. Despite its public health significance, the specific molecular and cellular basis of HCMV replication in the human placenta and pathogenesis associated with poor clinical outcome are unknown. Direct fetal infection is involved in severe cases of neuropathology and infection of the placenta can impair its development and functions resulting in a hypoxic environment5–8 and stillbirth6,9,10. Gestational age at the time of infection is an important determinant of outcome. The rates of virus transmission increase from 30% in first trimester to over 70% in third trimester suggesting different mechanisms for overcoming the placental barrier2. Remarkable insights into viral pathogenesis factors that function in the tissue environment have been gained by studying congenitally infected placentas and explants infected by clinical strains ex vivo. Together these studies revealed that direct infection of specialised placental cells and paracrine factors contribute to impaired development and functional defects.
Transmission of human cytomegalovirus via breastmilk and potential risks to very preterm infants
Authors: Hamprecht Klaus , Goelz Rangmar
Published: October 2015

Breastfeeding has clear short-term benefits for the baby1. Additionally, based on a prospective long-term cohort study from Brazil, breastfeeding is associated with improved IQ scores and increased educational attainment 30 years later2. During lactation, mother-to-infant transmission of viral infections like HIV, hepatitis B (HBV), and human cytomegalovirus (HCMV), may occur. The article presented here will focus on the dynamics of HCMV shedding into breastmilk, describe the short- and long-term risks of HCMV infection of small preterm infants, and options for prevention.
Assessment of the accuracy of profile available water and potential rooting depth estimates held within New Zealand
Authors: Pearse Grant , Moltchanova Elena , Bloomberg Mark
Published: October 2015

The Fundamental Soil Layers (FSL) serve historically as New Zealand’s primary source of soil information. They contain a range of New Zealand’s soil attribute information held in a spatial database. Despite their wide use in a range of applications, few direct assessments of the accuracy of FSL attribute information have been undertaken to date. This study aims to provide an assessment of the accuracy of the FSL by comparing observed data for Profile Available Water (PAW) and Potential Rooting Depth (PRD) with FSL estimates for these two attributes. Two datasets were used to conduct the tests. The first dataset (n = 35) contained measured observations for PAW and PRD. A second dataset (n = 173) contained measured observations for PRD only. A regression model found a weak relationship between measured values and FSL estimates for PAW and PRD (correlations ranged from –0.08 to 0.17). Additional FSL estimates provided in the form of class intervals were tested by calculating the proportion of observed values within the specified FSL class interval. The effect of estimate lineage (underlying data and estimation method) on the accuracy of the class intervals was assessed using a logistic regression. Overall the FSL estimates for PRD and PAW were inaccurate, and allowance for data lineage did not improve the accuracy of the FSL estimates.
Can the application of rare earth elements improve yield and decrease the uptake of cadmium in ryegrass-dominated pastures?
Authors: McDowell R. W. , Catto W. , Orchiston T.
Published: October 2015

Rare earth elements (REEs) have been linked to increases and decreases in plant growth and the uptake of biotoxic metals such as Cadmium (Cd). We hypothesised that under the right soil and climatic conditions the application REEs to soil may improve yield of ryegrass-dominated pasture and inhibit Cd uptake in foliage. A soil survey measuring REEs concentrations in soils from across New Zealand showed that REEs were enriched in Volcanic compared with Sedimentary-derived soils, and in soils used for dairying compared with those used for sheep and beef. From a range of REEs applied to ryegrass with and without N, lanthanum (La) showed minor yield improvement under glasshouse conditions, but only for Sedimentary (not Volcanic) soils low in REE concentration and at 40% available soil moisture or less. A similarly mixed yield response occurred in a field trial. Decreases in the Cd concentration of ryegrass (mg kg–1) only occurred in the harvests after application (40% at 20 kg La ha–1 for one soil) and did not translate into an annual effect. We conclude that there was insufficient evidence to recommend the use of La (screened from a range of REEs as the most promising) to increase annual dry matter yield or decrease Cd uptake from ryegrass-dominated pastures.
Accurate market price formation model with both supply-demand and trend-following for global food prices providing policy recommendations
Authors: Lagi Marco , Bar-Yam Yavni , Bertrand Karla Z. , Bar-Yam Yaneer
Published: October 2015

Significance

Recent increases in food prices are linked to widespread hunger and social unrest. The causes of high food prices have been debated. Here we rule out explanations that are not consistent with the data and construct a dynamic model of food prices using two factors determined to have the largest impact: corn-to-ethanol conversion and investor speculation. We overcome limitations of equilibrium theories that are unable to quantify the impact of speculation by using a dynamic model of trend following. The model accurately fits the data. Ethanol conversion results in a smooth price increase, whereas speculation results in bubbles and crashes. These findings significantly inform the discussion about food prices and market equilibrium and have immediate policy implications.
Determining hydrodynamic forces in bursting bubbles using DNA nanotube mechanics
Authors: Hariadi Rizal F. , Winfree Erik , Yurke Bernard
Published: October 2015

Significance

The hydrodynamic forces within bursting bubbles are of interest for their relevance to small-scale fluid mechanics, bioreactor efficiency, pollutant degradation, and the origin of life. However, despite the 150-year history of their study, the strengths of flows within bursting bubbles are only hypothetically known. Here, we show that DNA nanotubes––architecturally similar to biological microtubules—are fragmented during the bubble bursting process. Further, by analyzing the resulting fragment lengths, we characterize the spectrum of elongational flow rates, revealing that surprisingly strong tensile forces can be generated––in principle sufficient to fragment filamentous cyanobacterial chains, lipid vesicle protocells, genomic DNA, and other long polymeric molecules residing within or near the disintegrating liquid film.
Lion (
Panthera leo
) populations are declining rapidly across Africa, except in intensively managed areas
Authors: Bauer Hans , Chapron Guillaume , Nowell Kristin , Henschel Philipp , Funston Paul , Hunter Luke T. B. , Macdonald David W. , Packer Craig
Published: October 2015

Significance

At a regional scale, lion populations in West, Central, and East Africa are likely to suffer a projected 50% decline over the next two decades, whereas lion populations are only increasing in southern Africa. Many lion populations are either now gone or expected to disappear within the next few decades to the extent that the intensively managed populations in southern Africa may soon supersede the iconic savannah landscapes in East Africa as the most successful sites for lion conservation. The rapid disappearance of lions suggests a major trophic downgrading of African ecosystems with the lion no longer playing a pivotal role as apex predator.
The incidence and role of negative citations in science
Authors: Catalini Christian , Lacetera Nicola , Oettl Alexander
Published: October 2015

Significance

Providing a detailed classification of the types of citations that an article receives is important to establish the quality of a study and to characterize how current research builds upon prior work. The methodology that we propose also informs how to improve the citation process, for example by having scientists attach additional metadata to their citations. The approach is scalable to other fields and periods and can also be used to identify other types of citations (e.g., reuse of methods, materials, empirical tests of theory, and so on). Finally, our methods provide online repositories such as Google Scholar, PubMed, ISI Web of Science, and Scopus with a way to improve their search and ranking algorithms.
Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation
Authors: Bakker Elisabeth S. , Gill Jacquelyn L. , Johnson Christopher N. , Vera Frans W. M. , Sandom Christopher J. , Asner Gregory P. , Svenning Jens-Christian
Published: October 2015

Until recently in Earth history, very large herbivores (mammoths, ground sloths, diprotodons, and many others) occurred in most of the World’s terrestrial ecosystems, but the majority have gone extinct as part of the late-Quaternary extinctions. How has this large-scale removal of large herbivores affected landscape structure and ecosystem functioning? In this review, we combine paleo-data with information from modern exclosure experiments to assess the impact of large herbivores (and their disappearance) on woody species, landscape structure, and ecosystem functions. In modern landscapes characterized by intense herbivory, woody plants can persist by defending themselves or by association with defended species, can persist by growing in places that are physically inaccessible to herbivores, or can persist where high predator activity limits foraging by herbivores. At the landscape scale, different herbivore densities and assemblages may result in dynamic gradients in woody cover. The late-Quaternary extinctions were natural experiments in large-herbivore removal; the paleoecological record shows evidence of widespread changes in community composition and ecosystem structure and function, consistent with modern exclosure experiments. We propose a conceptual framework that describes the impact of large herbivores on woody plant abundance mediated by herbivore diversity and density, predicting that herbivore suppression of woody plants is strongest where herbivore diversity is high. We conclude that the decline of large herbivores induces major alterations in landscape structure and ecosystem functions.
Sea otters, kelp forests, and the extinction of Steller’s sea cow
Authors: Estes James A. , Burdin Alexander , Doak Daniel F.
Published: October 2015

Significance

Human-caused extinctions are normally thought to result from overexploitation or habitat alteration. A third possible cause of extinction is the loss of interactions associated with keystone species. Using recent and historical information on sea otters and kelp forests, we show that the extinction of Steller's sea cow from the Commander Islands in the mid-1700s would have been a nearly inevitable consequence of the overhunting of sea otters, which occurred a decade earlier.
The impact of large terrestrial carnivores on Pleistocene ecosystems
Authors: Van Valkenburgh Blaire , Hayward Matthew W. , Ripple William J. , Meloro Carlo , Roth V. Louise
Published: October 2015

Significance

At very high densities, populations of the largest herbivores, such as elephants, have devastating effects on the environment. What prevented widespread habitat destruction in the Pleistocene, when the ecosystem sustained many species of huge herbivores? We use data on predator–prey body mass relationships to predict the prey size ranges of large extinct mammalian carnivores, which were more diverse and much larger than living species. We then compare these prey size ranges with estimates of young mammoth sizes and show that juvenile mammoths and mastodons were within predicted prey size ranges of many of the Pleistocene carnivores. From this and other fossil evidence we argue that, by limiting population sizes of megaherbivores, large carnivores had a major impact on Pleistocene ecosystems.
No evidence that polygynous marriage is a harmful cultural practice in northern Tanzania
Authors: Lawson David W. , James Susan , Ngadaya Esther , Ngowi Bernard , Mfinanga Sayoki G. M. , Borgerhoff Mulder Monique
Published: October 2015

Significance

Polygynous marriage is commonly regarded as a harmful cultural practice, detrimental to women and children at the individual and group level. We present counterevidence that polygyny is often positively associated with food security and child health within communities and that, although polygyny and health are negatively associated at the group level, such differences are accounted for by alternative socioecological factors. These results support models of polygyny based on female choice and suggest that, in some contexts, prohibiting polygyny could be costly for women and children by restricting marital options. Our study highlights the dangers of naive analyses of aggregated population data and the importance of considering locally realizable alternatives and context dependency when considering the health implications of cultural practices.
OVO-like 1 regulates progenitor cell fate in human trophoblast development
Authors: Renaud Stephen J. , Chakraborty Damayanti , Mason Clifford W. , Rumi M. A. Karim , Vivian Jay L. , Soares Michael J.
Published: October 2015

Significance

Epithelial barrier integrity is dependent on progenitor cells that either divide to replenish themselves or differentiate into a functional epithelium. In the placenta, cytotrophoblast cells comprise this progenitor population, but the differentiation program they undertake is unlike any other in human tissues: acquisition of hormonogenesis and cell fusion to form a syncytialized (syncytio)trophoblast. Syncytiotrophoblast forms the primary epithelial barrier separating maternal and fetal tissue and performs functions vital for pregnancy. In the present study, we found that OVO-like 1 (OVOL1), a transcription factor homolog of Drosophila ovo, regulates the transition between progenitor and differentiated cytotrophoblast. It does so by repressing genes that maintain cytotrophoblast progenitor traits. This study provides insight into the role of OVOL1 in human trophoblast development.
Cortical entrainment to music and its modulation by expertise
Authors: Doelling Keith B. , Poeppel David
Published: October 2015

Significance

We demonstrate that cortical oscillatory activity in both low (<8 Hz) and high (15–30 Hz) frequencies is tightly coupled to behavioral performance in musical listening, in a bidirectional manner. In light of previous work on speech, we propose a framework in which the brain exploits the temporal regularities in music to accurately parse individual notes from the sound stream using lower frequencies (entrainment) and in higher frequencies to generate temporal and content-based predictions of subsequent note events associated with predictive models.
RNAIII of the
Staphylococcus aureus agr
system activates global regulator MgrA by stabilizing mRNA
Authors: Gupta Ravi Kr. , Luong Thanh T. , Lee Chia Y.
Published: October 2015

Significance

In
Staphylococcus aureus
, the
agr
quorum-sensing system is critical for regulation of many virulence genes, primarily through RNAIII, a small RNA. RNAIII functions by interacting with translational elements of its downstream genes typically by inhibiting translation initiation. Only a few direct targets of RNAIII have been identified, one of which is global regulator Rot. However, Rot can only partially account for RNAIII regulation. We show here that RNAIII can affect gene expression through another global regulator MgrA by enhancing MgrA production via mRNA stabilization, a novel mechanism of RNAIII regulation. Our findings provide evidence linking two major master regulators, thereby advancing our understanding of virulence regulation in this important human and animal pathogen.
Behavioral assessment of sensitivity to intracortical microstimulation of primate somatosensory cortex
Authors: Kim Sungshin , Callier Thierri , Tabot Gregg A. , Gaunt Robert A. , Tenore Francesco V. , Bensmaia Sliman J.
Published: October 2015

Significance

Electrical stimulation of sensory structures in the brain is a powerful tool to investigate neural circuits and may provide a means to restore sensation for patients for whom stimulation of the nerve is not an option. For both purposes, however, it is critical to understand how the design of the stimulation shapes the evoked sensory experience. With this in mind, we investigate the ability of monkeys to detect and discriminate trains of electrical pulses delivered to their somatosensory cortex through chronically implanted electrode arrays. We show that artificial touch is highly dependent on various features of the electrical stimuli and discuss the implications of our results for the use of electrical stimulation in neuroscience and neural engineering.
Effects of gendered behavior on testosterone in women and men
Authors: van Anders Sari M. , Steiger Jeffrey , Goldey Katherine L.
Published: October 2015

Significance

Human biology is typically studied within the framework of sex (evolved, innate factors) rather than gender (sociocultural factors), despite some attention to nature/nurture interactions. Testosterone is an exemplar of biology studied as natural difference: men’s higher testosterone is typically seen as an innate “sex” difference. However, our experiment demonstrates that gender-related social factors also matter, even for biological measures. Gender socialization may affect testosterone by encouraging men but not women toward behaviors that increase testosterone. This shows that research on human sex biology needs to account for gender socialization and that nurture, as well as nature, is salient to hormone physiology. Our paper provides a demonstration of a novel gender→testosterone pathway, opening up new avenues for studying gender biology.
Battle between influenza A virus and a newly identified antiviral activity of the PARP-containing ZAPL protein
Authors: Liu Chien-Hung , Zhou Ligang , Chen Guifang , Krug Robert M.
Published: October 2015

Significance

Influenza A viruses cause a contagious human respiratory disease that can result in high mortality rates. Here we identify a new antiviral activity of the cellular ZAPL protein. This activity involves its C-terminal PARP domain and is directed against influenza A virus. The ZAPL PARP domain binds the viral PA and PB2 proteins, leading to their degradation by the proteasome. This degradation pathway involves two posttranslational modifications of PA and PB2, poly(ADP-ribosylation) and ubiquitination. The viral PB1 protein counteracts ZAPL antiviral activity by binding close to the PARP domain, causing PA and PB2 to dissociate from ZAPL and escape degradation, indicating that the PB1 interface with ZAPL is a potential target for antiviral development.
Endocannabinoid signaling mediates oxytocin-driven social reward
Authors: Wei Don , Lee DaYeon , Cox Conor D. , Karsten Carley A. , Peñagarikano Olga , Geschwind Daniel H. , Gall Christine M. , Piomelli Daniele
Published: October 2015

Significance

We present evidence that an oxytocin-dependent endocannabinoid signal contributes to the regulation of social reward. The results provide insights into the functions of oxytocin, a neuropeptide crucial for social behavior, and its interactions with other modulatory systems that regulate the rewarding properties of social behavior. They further suggest that oxytocin-driven anandamide signaling may be defective in autism spectrum disorders, and that correcting such deficits might offer a strategy to treat these conditions.
Atlantic hurricane surge response to geoengineering
Authors: Moore John C. , Grinsted Aslak , Guo Xiaoran , Yu Xiaoyong , Jevrejeva Svetlana , Rinke Annette , Cui Xuefeng , Kravitz Ben , Lenton Andrew , Watanabe Shingo , Ji Duoying
Published: October 2015

Significance

We estimate that stratospheric sulfate aerosol geoengineering may somewhat ameliorate Atlantic hurricane intensity and frequency, but there will be more “Katrina”-level events than during the past 30 y. Geoengineering would likely be reasonably effective at controlling coastal flood risk relative to the coastal flood risk expected under the Representative Concentration Pathway (RCP) 4.5 greenhouse gas warming, in part, due to its impact on global sea level rise, although flood risk would still be significantly larger than at present.
Semisynthetic protein nanoreactor for single-molecule chemistry
Authors: Lee Joongoo , Bayley Hagan
Published: October 2015

Significance

The modulation of ionic current flowing through an individual protein pore provides information at the single-molecule level about chemical reactions occurring within the pore. However, chemistry investigated in this way has been largely confined to the reactions of thiolates, presented by the side chains of cysteine residues. The introduction of unnatural amino acids would provide a large variety of reactive side chains with which additional single-molecule chemistry could be investigated. Here we have produced semisynthetic protein pores containing a terminal alkyne and used the pores as a nanoreactor to study Cu(I)-catalyzed azide-alkyne cycloaddition. A long-lived intermediate (4.5 s) in the reaction was directly observed.
Ancient low–molecular-weight organic acids in permafrost fuel rapid carbon dioxide production upon thaw
Authors: Drake Travis W. , Wickland Kimberly P. , Spencer Robert G. M. , McKnight Diane M. , Striegl Robert G.
Published: October 2015

Significance

To our knowledge, this study is the first to directly link rapid microbial consumption of ancient permafrost-derived dissolved organic carbon (DOC) to CO
2
production using a novel bioreactor. Rapid mineralization of the freshly thawed DOC was attributed to microbial decomposition of low–molecular-weight organic acids, which were completely consumed during the experiments. Our results indicate that substantial biodegradation of permafrost DOC occurs immediately after thaw and before downstream transport occurs. We estimate that, by 2100, between 5 to 10 Tg of DOC will be released from Yedoma soils every year given the most recent estimates for projected thaw. This represents 19–26% of annual DOC loads exported by Arctic rivers, yet it is so far undetectable likely due to rapid mineralization in soils and/or headwater streams.
Effects of pressure on the dynamics of an oligomeric protein from deep-sea hyperthermophile
Authors: Shrestha Utsab R. , Bhowmik Debsindhu , Copley John R. D. , Tyagi Madhusudan , Leão Juscelino B. , Chu Xiang-qiang
Published: October 2015

Significance

Deep-sea microorganisms can adapt to extreme conditions of high temperature and pressure. What makes these organisms survive and reproduce in such critical conditions remains an open question. Here, we use the quasielastic neutron scattering (QENS) technique to study the dynamic behavior of a hyperthermophilic protein that is found in the deep sea. Our results give evidence that high pressure affects the dynamical properties of proteins by distorting the protein energy landscape in ways that are significantly different for hyperthermophilic and mesophilic proteins. Consequently, a general schematic denaturation phase diagram together with energy landscapes for the two different proteins are derived, and this approach can be used as a general picture to understand the effects of pressure on protein dynamics and activities.
Transcriptional read-through is not sufficient to induce an epigenetic switch in the silencing activity of Polycomb response elements
Authors: Erokhin Maksim , Elizar’ev Pavel , Parshikov Aleksander , Schedl Paul , Georgiev Pavel , Chetverina Darya
Published: October 2015

Significance

Gene silencing by Polycomb group (PcG) proteins is required to maintain tissue and stage-specific patterns of gene expression. PcG complexes assemble on special elements, Polycomb response elements (PREs), and function to silence gene activity in the surrounding domain. The activity of PREs is subject to regulation and can be epigenetically switched from “on” (silencing) to “off” (permissive for transcription) as development proceeds. Previous studies suggested that a burst of transcription through a PRE displaces PcG complexes, switching the PRE off in a heritable fashion. Here, we directly tested the transcription read-through hypothesis. We show that transcription through a PRE is not sufficient for induce a heritable switch. In fact, continuous transcription through a PRE fails to displace PcG complexes or eliminate repressive chromatin marks.
Importance of codon usage for the temporal regulation of viral gene expression
Authors: Shin Young C. , Bischof Georg F. , Lauer William A. , Desrosiers Ronald C.
Published: October 2015

Significance

We describe here that different families of persisting viruses consistently use highly unusual codon usage for synthesis of their structural gene products; that the specific nature of the skewed codon usage differs fundamentally from one virus family to another; and that viral-encoded regulatory proteins (specifically Rev of HIV/SIV and ORF57 of herpesviruses) recognize the specific nature of the skewed codon usage to allow expression of their structural gene products. The data include a stunning demonstration of the ability to flip Rev inducibility and ORF57 inducibility simply by changing the nature of the codon usage in the target gene.
Initiating protease with modular domains interacts with β-glucan recognition protein to trigger innate immune response in insects
Authors: Takahashi Daisuke , Garcia Brandon L. , Kanost Michael R.
Published: October 2015

Significance

Serine protease cascades in innate immune responses require autoactivation of initiating modular proteases in response to recognition of nonself/altered self. Molecular mechanisms linking pathogen recognition and protease autoactivation remain unclear. Here, we report biochemical interactions between
Manduca sexta
hemolymph protease 14 (HP14), an initiating protease in an immune cascade, with recognition protein β-1,3-glucan recognition protein (βGRP2). The amino-terminal LA domains of HP14 bind to βGRP2, and this interaction is essential for HP14 autoactivation. Binding of β-1,3-glucan to βGRP2 leads to a dramatic increase in affinity between HP14 LA domains and βGRP2, likely representing a mechanism for promoting HP14 activation upon infection. Our study provides an important insight into a previously unexplored mechanism for the initiation of an insect immune protease cascade.
Nanoscale spatial organization of the
HoxD
gene cluster in distinct transcriptional states
Authors: Fabre Pierre J. , Benke Alexander , Joye Elisabeth , Nguyen Huynh Thi Hanh , Manley Suliana , Duboule Denis
Published: October 2015

Significance

Ultrastructural chromatin dynamics may play a key role in regulating transcriptional activation. Here we have used super-resolution microscopy to study the folding mechanics of the
HoxD
cluster, as assayed by following the elongation of chromatin in single cells with different status of
Hox
gene activation. We observed that the spatial separation of
Hoxd
genes is strongest in those tissues where they are highly expressed. We also document that the opening of chromatin precedes transcription and that the strongest elongations are observed at the location of the boundary between two major topologically associating domains (TADs). These results shed light on how spatial compartmentalization is achieved, likely to accompany efficient chromatin reorganization upon activation of transcriptional switches.
Uterine endoplasmic reticulum stress-unfolded protein response regulation of gestational length is caspase-3 and -7–dependent
Authors: Kyathanahalli Chandrashekara , Organ Kenna , Moreci Rebecca S. , Anamthathmakula Prashanth , Hassan Sonia S. , Caritis Steve N. , Jeyasuria Pancharatnam , Condon Jennifer C.
Published: October 2015

Significance

Preterm birth is a leading cause of neonatal mortality, with a poorly understood etiology. The maintenance of uterine quiescence across gestation is fundamental for term parturition. At the molecular level, an integrated uterine endoplasmic reticulum stress-unfolded protein response (UPR-ERSR) regulates both caspase-3 (CASP3) and caspase-7 (CASP7), preserving myometrial quiescence throughout gestation. Here we show that prolonged ERSR diminishes the tocolytic potential of uterine CASP3 and 7, causing an increase in myometrial contractile responsiveness and onset of preterm labor in pregnant mice. Prophylaxis with 4-phenylbutrate, however, maintains active uterine CASP3 and 7 and prolongs gestational length. This study establishes a critical role for UPR-ERSR in the regulation of pregnant uterine myocyte quiescence.
Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels
Authors: Singh Meenesh R. , Clark Ezra L. , Bell Alexis T.
Published: October 2015

Significance

Direct capture of CO
2
from the air and its conversion to fuels using solar energy offers a means for mitigating global warming while also supporting future energy demands. Whereas natural photosynthesis converts CO
2
and water to carbohydrates, this process is only 0.5–2.0% efficient and the energy content of the resulting biomass is low. Increasing CO
2
levels in the atmosphere combined with rising energy needs motivate the search for an artificial photosynthetic system that is at least 10 times as efficient as that used by nature. Identification of light absorbers that provide a photocurrent density >10 mA cm
-2
and a photovoltage >2 V are prerequisites for a >10% efficient artificial photosynthetic system.
Topography of social touching depends on emotional bonds between humans
Authors: Suvilehto Juulia T. , Glerean Enrico , Dunbar Robin I. M. , Hari Riitta , Nummenmaa Lauri
Published: October 2015

Significance

Touch is a powerful tool for communicating positive emotions. However, it has remained unknown to what extent social touch would maintain and establish social bonds. We asked a total of 1,368 people from five countries to reveal, using an Internet-based topographical self-reporting tool, those parts of their body that they would allow relatives, friends, and strangers to touch. These body regions formed relationship-specific maps in which the total area was directly related to the strength of the emotional bond between the participant and the touching person. Cultural influences were minor. We suggest that these relation-specific bodily patterns of social touch constitute an important mechanism supporting the maintenance of human social bonds.
Doubly robust methods for handling confounding by cluster
Authors: Zetterqvist Johan , Vansteelandt Stijn , Pawitan Yudi , Sjölander Arvid
Published: October 2015

In clustered designs such as family studies, the exposure-outcome association is usually confounded by both cluster-constant and cluster-varying confounders. The influence of cluster-constant confounders can be eliminated by studying the exposure-outcome association within (conditional on) clusters, but additional regression modeling is usually required to control for observed cluster-varying confounders. A problem is that the working regression model may be misspecified, in which case the estimated within-cluster association may be biased. To reduce sensitivity to model misspecification we propose to augment the standard working model for the outcome with an auxiliary working model for the exposure. We derive a doubly robust conditional generalized estimating equation (DRCGEE) estimator for the within-cluster association. This estimator combines the two models in such a way that it is consistent if either model is correct, not necessarily both. Thus, the DRCGEE estimator gives the researcher two chances instead of only one to make valid inference on the within-cluster association. We have implemented the estimator in an R package and we use it to examine the association between smoking during pregnancy and cognitive abilities in offspring, in a sample of siblings.
Primary Larynx Cryptococcus neoformans Infection: A Distinctive Clinical Entity
Authors: Bergeron Mathieu , Gagné Andrée-Anne , Côté Mathieu , Chênevert Jacinthe , Dubé Robert , Pelletier René
Published: October 2015

Cryptococcus neoformans can directly infect the vocal cords. Endoscopic findings were undistinctive from most infiltrative diseases. Tissue biopsy was essential for the diagnosis. Inhaled corticosteroids can predispose to the infection, and fluconazole 400 mg daily for at least 6 weeks appeared to be minimal to achieve a permanent cure.