bluuebunny/crossref_metadata_2025 huggingface dataset:
Single shot x-ray phase contrast imaging using a direct conversion microstrip detector with single photon sensitivity
Authors: Kagias M. , Cartier S. , Wang Z. , Bergamaschi A. , Dinapoli R. , Mozzanica A. , Schmitt B. , Stampanoni M.
Published: June 2016

X-ray phase contrast imaging enables the measurement of the electron density of a sample with high sensitivity compared to the conventional absorption contrast. This is advantageous for the study of dose-sensitive samples, in particular, for biological and medical investigations. Recent developments relaxed the requirement for the beam coherence, such that conventional X-ray sources can be used for phase contrast imaging and thus clinical applications become possible. One of the prominent phase contrast imaging methods, Talbot-Lau grating interferometry, is limited by the manufacturing, alignment, and photon absorption of the analyzer grating, which is placed in the beam path in front of the detector. We propose an alternative improved method based on direct conversion charge integrating detectors, which enables a grating interferometer to be operated without an analyzer grating. Algorithms are introduced, which resolve interference fringes with a periodicity of 4.7 μm recorded with a 25 μm pitch Si microstrip detector (GOTTHARD). The feasibility of the proposed approach is demonstrated by an experiment at the TOMCAT beamline of the Swiss Light Source on a polyethylene sample.
An apparatus to estimate the hydrodynamic coefficients of autonomous underwater vehicles using water tunnel testing
Authors: Nouri N. M. , Mostafapour K. , Bahadori R.
Published: June 2016

Hydrodynamic coefficients or hydrodynamic derivatives of autonomous underwater vehicles (AUVs) play an important role in their development and maneuverability. The most popular way of estimating their coefficients is to implement captive model tests such as straight line tests and planar motion mechanism (PMM) tests in the towing tanks. This paper aims to develop an apparatus based on planar experiments of water tunnel in order to estimate hydrodynamic derivatives due to AUVs’ acceleration and velocity. The capability of implementing straight line tests and PMM ones using mechanical oscillators located in the downstream flow of the model is considered in the design procedure of the system. The hydrodynamic derivatives that resulted from the acceleration and velocity of the AUV model were estimated using the apparatus that we developed. Static and dynamics test results were compared for the similar derivatives. The findings showed that the system provided the basis for conducting static tests, i.e., straight-line and dynamic tests that included pure pitch and pure heave. By conducting such tests in a water tunnel, we were able to eliminate errors related to the time limitation of the tests and the effects of surface waves in the towing tank on AUVs with applications in the deep sea.
Viscoelastic response of neural cells governed by the deposition of amyloid-β peptides (Aβ)
Authors: Gong Ze , You Ran , Chang Raymond Chuen-Chung , Lin Yuan
Published: June 2016

Because of its intimate relation with Alzheimer's disease (AD), the question of how amyloid-β peptide (Aβ) deposition alters the membrane and cytoskeltal structure of neural cells and eventually their mechanical response has received great attention. In this study, the viscoelastic properties of primary neurons subjected to various Aβ treatments were systematically characterized using atomic force microrheology. It was found that both the storage (G′) and loss (G″) moduli of neural cells are rate-dependent and grow by orders of magnitude as the driving frequency ω varies from 1 to 100 Hz. However, a much stronger frequency dependence was observed in the loss moduli (with a scaling exponent of ∼0.96) than that in G′ (∼ω0.2). Furthermore, both cell moduli increase gradually within the first 6 h of Aβ treatment before steady-state values are reached, with a higher dosage of Aβ leading to larger changes in cell properties. Interestingly, we showed that the measured neuron response can be well-explained by a power law structural damping model. Findings here establish a quantitative link between Aβ accumulation and the physical characteristics of neural cells and hence could provide new insights into how disorders like AD affect the progression of different neurological processes from a mechanics point of view.
Fabrication of all diamond scanning probes for nanoscale magnetometry
Authors: Appel Patrick , Neu Elke , Ganzhorn Marc , Barfuss Arne , Batzer Marietta , Gratz Micha , Tschöpe Andreas , Maletinsky Patrick
Published: June 2016

The electronic spin of the nitrogen vacancy (NV) center in diamond forms an atomically sized, highly sensitive sensor for magnetic fields. To harness the full potential of individual NV centers for sensing with high sensitivity and nanoscale spatial resolution, NV centers have to be incorporated into scanning probe structures enabling controlled scanning in close proximity to the sample surface. Here, we present an optimized procedure to fabricate single-crystal, all-diamond scanning probes starting from commercially available diamond and show a highly efficient and robust approach for integrating these devices in a generic atomic force microscope. Our scanning probes consisting of a scanning nanopillar (200 nm diameter, 1–2 μm length) on a thin (<1 μm) cantilever structure enable efficient light extraction from diamond in combination with a high magnetic field sensitivity (ηAC≈50±20nT/Hz). As a first application of our scanning probes, we image the magnetic stray field of a single Ni nanorod. We show that this stray field can be approximated by a single dipole and estimate the NV-to-sample distance to a few tens of nanometer, which sets the achievable resolution of our scanning probes.
High energy X-ray pinhole imaging at the Z facility
Authors: McPherson L. Armon , Ampleford David J. , Coverdale Christine A. , Argo Jeffrey W. , Owen Albert C. , Jaramillo Deanna M.
Published: June 2016

A new high photon energy (hν > 15 keV) time-integrated pinhole camera (TIPC) has been developed as a diagnostic instrument at the Z facility. This camera employs five pinholes in a linear array for recording five images at once onto an image plate detector. Each pinhole may be independently filtered to yield five different spectral responses. The pinhole array is fabricated from a 1-cm thick tungsten block and is available with either straight pinholes or conical pinholes. Each pinhole within the array block is 250 μm in diameter. The five pinholes are splayed with respect to each other such that they point to the same location in space, and hence present the same view of the radiation source at the Z facility. The fielding distance from the radiation source is 66 cm and the nominal image magnification is 0.374. Initial experimental results from TIPC are shown to illustrate the performance of the camera.
Magnetoelectroluminescence in organic light-emitting diodes
Authors: Lawrence Joseph E. , Lewis Alan M. , Manolopoulos David E. , Hore P. J.
Published: June 2016

The magnetoelectroluminescence of conjugated organic polymer films is widely accepted to arise from a polaron pair mechanism, but their magnetoconductance is less well understood. Here we derive a new relationship between the experimentally measurable magnetoelectroluminescence and magnetoconductance and the theoretically calculable singlet yield of the polaron pair recombination reaction. This relationship is expected to be valid regardless of the mechanism of the magnetoconductance, provided the mobilities of the free polarons are independent of the applied magnetic field (i.e., provided one discounts the possibility of spin-dependent transport). We also discuss the semiclassical calculation of the singlet yield of the polaron pair recombination reaction for materials such as poly(2,5-dioctyloxy-paraphenylene vinylene) (DOO-PPV), the hyperfine fields in the polarons of which can be extracted from light-induced electron spin resonance measurements. The resulting theory is shown to give good agreement with experimental data for both normal (H-) and deuterated (D-) DOO-PPV over a wide range of magnetic field strengths once singlet-triplet dephasing is taken into account. Without this effect, which has not been included in any previous simulation of magnetoelectroluminescence, it is not possible to reproduce the experimental data for both isotopologues in a consistent fashion. Our results also indicate that the magnetoconductance of DOO-PPV cannot be solely due to the effect of the magnetic field on the dissociation of polaron pairs.
Trapped charge densities in Al2O3-based silicon surface passivation layers
Authors: Jordan Paul M. , Simon Daniel K. , Mikolajick Thomas , Dirnstorfer Ingo
Published: June 2016

In Al2O3-based passivation layers, the formation of fixed charges and trap sites can be strongly influenced by small modifications in the stack layout. Fixed and trapped charge densities are characterized with capacitance voltage profiling and trap spectroscopy by charge injection and sensing, respectively. Al2O3 layers are grown by atomic layer deposition with very thin (∼1 nm) SiO2 or HfO2 interlayers or interface layers. In SiO2/Al2O3 and HfO2/Al2O3 stacks, both fixed charges and trap sites are reduced by at least a factor of 5 compared with the value measured in pure Al2O3. In Al2O3/SiO2/Al2O3 or Al2O3/HfO2/Al2O3 stacks, very high total charge densities of up to 9 × 1012 cm−2 are achieved. These charge densities are described as functions of electrical stress voltage, time, and the Al2O3 layer thickness between silicon and the HfO2 or the SiO2 interlayer. Despite the strong variation of trap sites, all stacks reach very good effective carrier lifetimes of up to 8 and 20 ms on p- and n-type silicon substrates, respectively. Controlling the trap sites in Al2O3 layers opens the possibility to engineer the field-effect passivation in the solar cells.
Extracting information from multiplex networks
Authors: Iacovacci Jacopo , Bianconi Ginestra
Published: June 2016

Multiplex networks are generalized network structures that are able to describe networks in which the same set of nodes are connected by links that have different connotations. Multiplex networks are ubiquitous since they describe social, financial, engineering, and biological networks as well. Extending our ability to analyze complex networks to multiplex network structures increases greatly the level of information that is possible to extract from big data. For these reasons, characterizing the centrality of nodes in multiplex networks and finding new ways to solve challenging inference problems defined on multiplex networks are fundamental questions of network science. In this paper, we discuss the relevance of the Multiplex PageRank algorithm for measuring the centrality of nodes in multilayer networks and we characterize the utility of the recently introduced indicator function Θ̃S for describing their mesoscale organization and community structure. As working examples for studying these measures, we consider three multiplex network datasets coming for social science.
Effect of laser intensity on radio frequency emissions from laser induced breakdown of atmospheric air
Authors: Vinoth Kumar L. , Manikanta E. , Leela Ch. , Prem Kiran P.
Published: June 2016

The studies on the effect of input laser intensity, through the variation of laser focusing geometry, on radio frequency (RF) emissions, over 30–1000 MHz from nanosecond (ns) and picosecond (ps) laser induced breakdown (LIB) of atmospheric air are presented. The RF emissions from the ns and ps LIB were observed to be decreasing and increasing, respectively, when traversed from tight to loose focusing conditions. The angular and radial intensities of the RF emissions from the ns and ps LIB are found to be consistent with sin2θ/r2 dependence of the electric dipole radiation. The normalized RF emissions were observed to vary with incident laser intensity (Iλ2), indicating the increase in the induced dipole moment at moderate input laser intensities and the damping of radiation due to higher recombination rate of plasma at higher input laser intensities.
Pressure-induced phase transitions of exposed curved surface nano-TiO2 with high photocatalytic activity
Authors: Huang Yanwei , Chen Fengjiao , Li Xin , Yuan Ye , Dong Haini , Samanta Sudeshna , Yu Zhenhai , Rahman Saqib , Zhang Jun , Yang Ke , Yan Shuai , Wang Lin
Published: June 2016

We report a unique phase transition in compressed exposed curved surface nano-TiO2 with high photocatalytic activity using in situ synchrotron X-ray diffraction and Raman Spectroscopy. High-pressure studies indicate that the anatase phase starts to transform into baddeleyite phase upon compression at 19.4 GPa, and completely transforms into the baddeleyite phase above 24.6 GPa. Upon decompression, the baddeleyite phase was maintained until the pressure was released to 6.4 GPa and then transformed into the α-PbO2 phase at 2.7 GPa. Together with the results of high-resolution transmission electron microscopy and the pressure-volume relationship, this phase transition's characteristics during the compression-decompression cycle demonstrate that the truncated biconic morphology possessed excellent stability. This study may provide an insight to the mechanisms of stability for high photocatalytic activity of nano-TiO2.
Electromodulation spectroscopy of direct optical transitions in Ge1−xSnx layers under hydrostatic pressure and built-in strain
Authors: Dybała F. , Żelazna K. , Maczko H. , Gladysiewicz M. , Misiewicz J. , Kudrawiec R. , Lin H. , Chen R. , Shang C. , Huo Y. , Kamins T. I. , Harris J. S.
Published: June 2016

Unstrained Ge1−xSnx layers of various Sn concentration (1.5%, 3%, 6% Sn) and Ge0.97Sn0.03 layers with built-in compressive (ε = −0.5%) and tensile (ε = 0.3%) strain are grown by molecular beam epitaxy and studied by electromodulation spectroscopy (i.e., contactless electroreflectance and photoreflectance (PR)). In order to obtain unstrained GeSn layers and layers with different built-in in-plane strains, virtual InGaAs substrates of different compositions are grown prior to the deposition of GeSn layers. For unstrained Ge1−xSnx layers, the pressure coefficient for the direct band gap transition is determined from PR measurements at various hydrostatic pressures to be 12.2 ± 0.2 meV/kbar, which is very close to the pressure coefficient for the direct band gap transition in Ge (12.9 meV/kbar). This suggests that the hydrostatic deformation potentials typical of Ge can be applied to describe the pressure-induced changes in the electronic band structure of Ge1−xSnx alloys with low Sn concentrations. The same conclusion is derived for the uniaxial deformation potential, which describes the splitting between heavy-hole (HH) and light-hole (LH) bands as well as the strain-related shift of the spin-orbit (SO) split-off band. It is observed that the HH, LH, and SO related transitions shift due to compressive and tensile strain according to the Bir-Pikus theory. The dispersions of HH, LH, and SO bands are calculated for compressive and tensile strained Ge0.97Sn0.03 with the 8-band kp Hamiltonian including strain effects, and the mixing of HH and LH bands is discussed. In addition, the dispersion of the electronic band structure is calculated for unstrained Ge1−xSnx layers (3% and 6% Sn) at high hydrostatic pressure with the 8-band kp Hamiltonian, and the pressure-induced changes in the electronic band structure are discussed.
Investigation on nanoscale processes on the BaF2(111) surface in various solutions by frequency modulation atomic force microscopy
Authors: Kobayashi Naritaka , Kawamura Ryuzo , Yoshikawa Hiroshi Y. , Nakabayashi Seiichiro
Published: June 2016

In this study, we have directly observed nanoscale processes that occur on BaF2(111) surfaces in various solutions using liquid-environment frequency modulation atomic force microscopy (FM-AFM) with a true atomic resolution. In addition, to investigate atomic-scale mechanisms of crystal growth process of BaF2, we determined a suitable solution for atomic-resolution FM-AFM imaging of the BaF2(111) surface. For undersaturated solutions, the surface is roughened by barium hydroxo complexes in the case of high pH, whereas by dissolution and proton or water molecule adsorption throughout the surface in the case of low pH. On the other hand, for supersaturated solutions, the surface shows two-dimensional nucleation and growth (σ = 0.1) and three-dimensional crystal growth with tetrahedral structures (σ = 1), where σ is the degree of supersaturation. The atomic-resolution imaging of the BaF2(111) surface has been demonstrated in potassium fluoride (KF) and the supersaturated (σ = 0.1 and 1) solutions, wherein atomically flat terraces are shown at least for about 30 min.
Inverse and normal magnetocaloric effects in LaFe12B6
Authors: Diop L. V. B. , Isnard O.
Published: June 2016

Intrinsic magnetic properties and magnetocaloric effect were studied for LaFe12B6 itinerant-electron system, which presents an antiferromagnetic ground state below 36 K. For certain magnetic fields values, LaFe12B6 exhibits a sequence of two successive magnetic transitions: an antiferromagnetic-ferromagnetic (AFM-FM) transition at low temperature followed by a ferromagnetic-paramagnetic transition, leading to normal and inverse magnetocaloric effects, respectively. At finite temperatures, both antiferromagnetic (AFM) and paramagnetic states can be transformed into a ferromagnetic (FM) state via a field-induced metamagnetic transition accompanied with a huge magnetic hysteresis. Moreover, we reveal that, at low temperatures, the magnetization displays abrupt jumps across the first-order AFM-FM transition, giving rise to an unusual and unique staircase-like behavior. LaFe12B6 exhibits both normal magnetocaloric effect around the Curie temperature and large inverse magnetocaloric effect around the AFM-FM transition temperature; for μ0ΔH = 7 T, ΔSM is found to be −6.8 and 19 J kg−1 K−1 around 38 and 8 K, respectively.
Investigation of InGaN/GaN laser degradation based on luminescence properties
Authors: Wen Pengyan , Zhang Shuming , Liu Jianping , Li Deyao , Zhang Liqun , Sun Qian , Tian Aiqin , Zhou Kun , Zhou Taofei , Yang Hui
Published: June 2016

Degradation of InGaN/GaN laser diode (LD) is investigated based on the luminescence properties. Gradual degradation of the LD is presented with the threshold current increase and the slope efficiency decrease. The cathodoluminescence and photoluminescence characterizations of the LD show a dislocation independent degradation of the active region under the ridge. Detailed studies on the temperature-dependent micro-photoluminescence and the electroluminescence indicate that the degradation of the LD is attributed to the generation of non-radiative recombination centers in the local multiple quantum well regions with lower indium content. The activation energy of the non-radiative recombination centers is about 10.2 meV.
Mid-infrared metasurface made of composite right/left-handed transmission-line
Authors: Luo Yi , Ying Xiangxiao , Pu Yang , Jiang Yadong , Xu Jimmy , Liu Zhijun
Published: June 2016

We report on the realization of a mid-infrared metasurface based on the concept of composite right/left-handed transmission-line. The metasurface consists of a three-layer metal-insulator-metal structure patterned into transmission-lines by electron-beam lithography. Angle-variable reflection spectroscopy measurements reveal resonant absorption features corresponding to both right- and left-handed propagations in the leaky-wave guided mode region. Material loss is shown to dominate the quality factor of the left-handed modes, while the radiative loss dominates the right-handed ones. The experimental results are in good agreement with full-wave numerical simulations and are explained with an equivalent circuit model.
Microfabrication of large-area circular high-stress silicon nitride membranes for optomechanical applications
Authors: Serra E. , Bawaj M. , Borrielli A. , Di Giuseppe G. , Forte S. , Kralj N. , Malossi N. , Marconi L. , Marin F. , Marino F. , Morana B. , Natali R. , Pandraud G. , Pontin A. , Prodi G. A. , Rossi M. , Sarro P. M. , Vitali D. , Bonaldi M.
Published: June 2016

In view of the integration of membrane resonators with more complex MEMS structures, we developed a general fabrication procedure for circular shape SiNx membranes using Deep Reactive Ion Etching (DRIE). Large area and high-stress SiNx membranes were fabricated and used as optomechanical resonators in a Michelson interferometer, where Q values up to 1.3 × 106 were measured at cryogenic temperatures, and in a Fabry-Pérot cavity, where an optical finesse up to 50000 has been observed.
Novel Thymohydroquinone Derivatives as Potential Anticancer Agents: Design, Synthesis, and Biological Screening
Authors: Abdelazeem Ahmed H. , Mohamed Yasser M. A. , Gouda Ahmed M. , Omar Hany A. , Al Robaian Majed M.
Published: June 2016

The safety and efficacy of naturally occurring anticancer agents and their derivatives such as thymoquinone (TQ) and thymohydroquinone (THQ) have gained a rapidly growing interest. In an attempt to develop novel anticancer agents with superior activity, TQ was allowed to react with hydrazine hydrate, producing hydrazino thymohydroquinone 3. This new intermediate was subsequently reacted with various isocyanates, isothiocyanates, and acyl halides, affording three series of semicarbazone, semithiocarbazone, and acyl hydrazone derivatives, respectively. Subsequently, the anticancer activity of all the newly synthesised compounds against a panel of cancer cell lines was evaluated. Initial screening of the ability of the test compounds to inhibit cancer cell viability using the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay revealed that compounds 5d and 6 exerted better activity against breast cancer than TQ, with half-maximal inhibitory concentration (IC50) values of 9.6 and 10.0 μM, respectively. MTT results were confirmed by the ability of these compounds to elicit apoptotic cell death through the activation of caspase 3/7 enzymes. Together, the present work provided a novel class of THQ-based derivatives with potent anticancer and apoptosis properties, thereby warranting further optimisation of these derivatives as novel members in cancer treatment protocols.
Reduced soybean photosynthetic nitrogen use efficiency associated with evolutionary genetic bottlenecks
Authors: Rotundo José L. , Borrás Lucas
Published: June 2016

Soybean has a narrow genetic base thought to limit future yield genetic gains. However, there is no evidence whether this reduction in genetic diversity correlates with diversity loss for any yield trait. We tested how photosynthetic nitrogen use efficiency (leaf photosynthesis per unit nitrogen, NUEp) evolved from the wild relative Glycine soja Siebold & Zucc. to the current Glycine max (L.) Merr. Five populations resulting from different evolutionary bottlenecks were evaluated under field conditions. Populations were wild ancestors, domesticated Asian landraces, North American ancestors, and modern cultivars. Genotypic differences in photosynthesis and leaf nitrogen were evident, creating a significant 3-fold variation in phenotypic NUEp. There was a parallel reduction in molecular marker and phenotypic NUEp diversity after each evolutionary bottleneck. G. soja had three times more NUEp diversity and 25% more average NUEp compared with the elite modern cultivars. Two strategies for increasing NUEp were identified: (i) increases in light saturated photosynthesis (Pmax), and, alternatively, (ii) reductions in leaf nitrogen. A modelling approach showed that NUEp will increase yield only if based on increased Pmax. Our study quantified the genetic potential of exotic germplasm available for trait-directed breeding. Results antagonise the concept that elite germplasm is always superior for any relevant yield trait when compared with undomesticated germplasm.
Salinity tolerances of three succulent halophytes (Tecticornia spp.) differentially distributed along a salinity gradient
Authors: Moir-Barnetson Louis , Veneklaas Erik J. , Colmer Timothy D.
Published: June 2016

We evaluated tolerances to salinity (10–2000 mM NaCl) in three halophytic succulent Tecticornia species that are differentially distributed along a salinity gradient at an ephemeral salt lake. The three species showed similar relative shoot and root growth rates at 10–1200 mM NaCl; at 2000 mM NaCl, T. indica subsp. bidens (Nees) K.A.Sheph and P.G.Wilson died, but T. medusa (K.A.Sheph and S.J.van Leeuwen) and T. auriculata (P.G.Wilson) K.A.Sheph and P.G.Wilson survived but showed highly diminished growth rates and were at incipient water stress. The mechanisms of salinity tolerance did not differ among the three species and involved the osmotic adjustment of succulent shoot tissues by the accumulation of Na+, Cl– and the compatible solute glycinebetaine, and the maintenance of high net K+ to Na+ selectivity to the shoot. Growth at extreme salinity was presumably limited by the capacity for vacuolar Na+ and Cl– uptake to provide sufficiently low tissue osmotic potentials for turgor-driven growth. Tissue sugar concentrations were not reduced at high salinity, suggesting that declines in growth would not have been caused by inadequate photosynthesis and substrate limitation compared with plants at low salinity. Equable salt tolerance among the three species up to 1200 mM NaCl means that other factors are likely to contribute to species composition at sites with salinities below this level. The lower NaCl tolerance threshold for survival in T. indica suggests that this species would be competitively inferior to T. medusa and T. auriculata in extremely saline soils.
Placing the Fijian Honeyeaters within the meliphagid radiation: implications for origins and conservation
Authors: Yabaki Mere , Winkworth Richard C. , McLenachan Patricia A. , Aalbersberg William , Winder Linton , Trewick Steven A. , Lockhart Peter J.
Published: June 2016

Understanding the evolutionary relationships of threatened species provides an important framework for making decisions about their conservation. However, unrecognised problems with the underlying phylogenetic analyses may bias the decision-making process. Recent phylogenetic studies have improved our understanding of Meliphagidae, but also indicate discordance between molecular datasets. Here, we examine the causes of this discordance using maximum likelihood tree-building and network analyses of identically sampled datasets for four genetic loci. Our results suggest that while we can be reasonably confident of relationships within species groups, discordance within and between molecular datasets tends to obscure relationships towards the base of the meliphagid tree. This ongoing uncertainty likely reflects differences in the sampling of markers and taxa between previously published analyses. To avoid the problems of conflicting data we used divergence time analyses of only the most densely sampled marker, NADH-ubiquinone oxidoreductase chain 2, to investigate the age and origins of the Fijian Meliphagidae. Our analyses suggest two temporally distinct colonisations of the Fijian archipelago. The large-bodied honeyeaters arrived ~15.6 million years ago, subsequently diversifying and spreading to Tonga and Samoa. In contrast, Myzomela appears to have arrived within the last 5.0 million years. The phylogenetic results therefore imply that conserving the evolutionary diversity of Meliphagidae in Polynesia requires that effort be spread across both the currently recognised taxa and geographical range.
Ancient mtDNA sequences from the First Australians revisited
Authors: Heupink Tim H. , Subramanian Sankar , Wright Joanne L. , Endicott Phillip , Westaway Michael Carrington , Huynen Leon , Parson Walther , Millar Craig D. , Willerslev Eske , Lambert David M.
Published: June 2016

Significance

This report is the first publication, to our knowledge, to report the complete mitochondrial genome of an ancient Aboriginal Australian. In addition, it also provides important evidence about the reliability of the only previous publication of this kind. The paper attained international significance, although its conclusions have remained controversial. Using second generation DNA sequencing methods, we provide strong evidence that the DNA sequences reported by Adcock et al. were, indeed, contamination. Our manuscript is also important, because the research was planned and conducted and is published with the support of the Barkindji, Ngiyampaa, and Muthi Muthi indigenous groups.
The Pliocene hominin diversity conundrum: Do more fossils mean less clarity?
Authors: Haile-Selassie Yohannes , Melillo Stephanie M. , Su Denise F.
Published: June 2016

Recent discoveries of multiple middle Pliocene hominins have raised the possibility that early hominins were as speciose as later hominins. However, debates continue to arise around the validity of most of these new taxa, largely based on poor preservation of holotype specimens, small sample size, or the lack of evidence for ecological diversity. A closer look at the currently available fossil evidence from Ethiopia, Kenya, and Chad indicate that
Australopithecus afarensis
was not the only hominin species during the middle Pliocene, and that there were other species clearly distinguishable from it by their locomotor adaptation and diet. Although there is no doubt that the presence of multiple species during the middle Pliocene opens new windows into our evolutionary past, it also complicates our understanding of early hominin taxonomy and phylogenetic relationships.
Early farmers from across Europe directly descended from Neolithic Aegeans
Authors: Hofmanová Zuzana , Kreutzer Susanne , Hellenthal Garrett , Sell Christian , Diekmann Yoan , Díez-del-Molino David , van Dorp Lucy , López Saioa , Kousathanas Athanasios , Link Vivian , Kirsanow Karola , Cassidy Lara M. , Martiniano Rui , Strobel Melanie , Scheu Amelie , Kotsakis Kostas , Halstead Paul , Triantaphyllou Sevi , Kyparissi-Apostolika Nina , Urem-Kotsou Dushka , Ziota Christina , Adaktylou Fotini , Gopalan Shyamalika , Bobo Dean M. , Winkelbach Laura , Blöcher Jens , Unterländer Martina , Leuenberger Christoph , Çilingiroğlu Çiler , Horejs Barbara , Gerritsen Fokke , Shennan Stephen J. , Bradley Daniel G. , Currat Mathias , Veeramah Krishna R. , Wegmann Daniel , Thomas Mark G. , Papageorgopoulou Christina , Burger Joachim
Published: June 2016

Significance

One of the most enduring and widely debated questions in prehistoric archaeology concerns the origins of Europe’s earliest farmers: Were they the descendants of local hunter-gatherers, or did they migrate from southwestern Asia, where farming began? We recover genome-wide DNA sequences from early farmers on both the European and Asian sides of the Aegean to reveal an unbroken chain of ancestry leading from central and southwestern Europe back to Greece and northwestern Anatolia. Our study provides the coup de grâce to the notion that farming spread into and across Europe via the dissemination of ideas but without, or with only a limited, migration of people.
Ancient DNA and human history
Authors: Slatkin Montgomery , Racimo Fernando
Published: June 2016

We review studies of genomic data obtained by sequencing hominin fossils with particular emphasis on the unique information that ancient DNA (aDNA) can provide about the demographic history of humans and our closest relatives. We concentrate on nuclear genomic sequences that have been published in the past few years. In many cases, particularly in the Arctic, the Americas, and Europe, aDNA has revealed historical demographic patterns in a way that could not be resolved by analyzing present-day genomes alone. Ancient DNA from archaic hominins has revealed a rich history of admixture between early modern humans, Neanderthals, and Denisovans, and has allowed us to disentangle complex selective processes. Information from aDNA studies is nowhere near saturation, and we believe that future aDNA sequences will continue to change our understanding of hominin history.
Scaling identity connects human mobility and social interactions
Authors: Deville Pierre , Song Chaoming , Eagle Nathan , Blondel Vincent D. , Barabási Albert-László , Wang Dashun
Published: June 2016

Significance

Both our mobility and communication patterns obey spatial constraints: Most of the time, our trips or communications occur over a short distance, and occasionally, we take longer trips or call a friend who lives far away. These spatial dependencies, best described as power laws, play a consequential role in broad areas ranging from how an epidemic spreads to diffusion of ideas and information. Here we established the first formal link, to our knowledge, between mobility and communication patterns by deriving a scaling relationship connecting them. The uncovered scaling theory not only allows us to derive human movements from communication volumes, or vice versa, but it also documents a new degree of regularity that helps deepen our quantitative understanding of human behavior.
Directed vaccination against pneumococcal disease
Authors: Li Yi , Hill Andrew , Beitelshees Marie , Shao Shuai , Lovell Jonathan F. , Davidson Bruce A. , Knight Paul R. , Hakansson Anders P. , Pfeifer Blaine A. , Jones Charles H.
Published: June 2016

Significance

Pneumococcal disease represents a global health problem, especially for the young, the elderly, and the resource-limited. Disease progression begins with asymptomatic nasopharyngeal bacterial colonization before subsequent dissemination and disease (pneumonia, sepsis, and middle ear infection). Analysis of this transition from colonization to disease provided antigens that were tested in this study for directed vaccination against only the virulent subset of pneumococci. In so doing, a “smart” vaccine was sought that would address this disease broadly, effectively, and selectively.
Leaping eels electrify threats, supporting Humboldt’s account of a battle with horses
Authors: Catania Kenneth C.
Published: June 2016

Significance

Electric eels are shown to leap from the water to directly electrify threats. This shocking behavior likely allows electric eels to defend themselves during the Amazonian dry season, when they may be found in small pools and in danger of predation. The results support Alexander von Humboldt’s story of electric eels attacking horses that had been herded into a muddy pool during the dry season in 1800. The finding highlights sophisticated behaviors that have evolved in concert with the eel’s powerful electrical organs.
Measurement of background gamma radiation in the northern Marshall Islands
Authors: Bordner Autumn S. , Crosswell Danielle A. , Katz Ainsley O. , Shah Jill T. , Zhang Catherine R. , Nikolic-Hughes Ivana , Hughes Emlyn W. , Ruderman Malvin A.
Published: June 2016

Significance

Sixty-seven nuclear tests were conducted on two atolls in the northern Marshall Islands between 1946 and 1958. These tests produced radioactive fallout, which even today gives rise to radiation measurable above naturally occurring background levels. Rather than obtain new data, recent estimates of contamination levels in the northern Marshall Islands use measurements made decades ago to calculate present radiation levels. In contrast, we report on timely measurements on three different atolls, and also provide detailed fits and simulated maps across several islands, including the islands of Bikini and Rongelap. Bikini and Rongelap Islands are of particular interest as they are relevant to the discussion of human resettlement; indeed, our radiation values for Bikini Island are higher than those previously reported.
Role of quasiresonant planetary wave dynamics in recent boreal spring-to-autumn extreme events
Authors: Petoukhov Vladimir , Petri Stefan , Rahmstorf Stefan , Coumou Dim , Kornhuber Kai , Schellnhuber Hans Joachim
Published: June 2016

Significance

Weather extremes are becoming more frequent and severe in many regions of the world. The physical mechanisms have not been fully identified yet, but there is growing evidence that there are connections to planetary wave dynamics. Our study shows that, in boreal spring-to-autumn 2012 and 2013, a majority of the weather extremes in the Northern Hemisphere midlatitudes were accompanied by highly magnified planetary waves with zonal wave numbers
m
= 6, 7, and 8. A substantial part of those waves was probably forced by subseasonal variability in the extratropical midtroposphere circulation via the mechanism of quasiresonant amplification (QRA). The results presented here support the overall hypothesis that QRA is an important mechanism driving many of the recent exceptional extreme weather events.
Pseudomonas syringae
type III effector HopAF1 suppresses plant immunity by targeting methionine recycling to block ethylene induction
Authors: Washington Erica J. , Mukhtar M. Shahid , Finkel Omri M. , Wan Li , Banfield Mark J. , Kieber Joseph J. , Dangl Jeffery L.
Published: June 2016

Significance

Pseudomonas syringae
is a Gram-negative bacterium that uses a type III secretion system to inject type III effector (T3E) proteins into the host to cause disease in plants. Multiple
P
.
syringae
T3Es promote virulence by targeting immune system signaling pathways using diverse biochemical mechanisms. We provide evidence for a molecular function of the
P
.
syringae
T3E HopAF1. We demonstrate that the C-terminal region of HopAF1 has structural homology to deamidases. We demonstrate that an enzyme important for production of the gaseous signaling hormone ethylene is a target for HopAF1 and show that HopAF1 targets methylthioadenosine nucleosidase proteins MTN1 and MTN2 to dampen ethylene production during bacterial infection.
A scalable strategy for high-throughput GFP tagging of endogenous human proteins
Authors: Leonetti Manuel D. , Sekine Sayaka , Kamiyama Daichi , Weissman Jonathan S. , Huang Bo
Published: June 2016

Significance

The function of a large fraction of the human proteome still remains poorly characterized. Tagging proteins with a functional sequence is a powerful way to access function, and inserting tags at endogenous genomic loci allows the preservation of a near-native cellular background. To characterize the cellular role of human proteins in a systematic manner and in a native context, we developed a method for tagging endogenous human proteins with GFP that is both rapid and readily applicable at a genome-wide scale. Our approach allows studying both localization and interaction partners of the protein target. Our results pave the way for the large-scale generation of endogenously tagged human cell lines for a systematic functional interrogation of the human proteome.
GEFs and Rac GTPases control directional specificity of neurite extension along the anterior–posterior axis
Authors: Zheng Chaogu , Diaz-Cuadros Margarete , Chalfie Martin
Published: June 2016

Significance

Most previous studies on intracellular signaling during neurite guidance were performed in the context of unidirectional neurite growth. They could not address the molecular basis of directional outgrowth of multiple neurites mainly because of the lack of a good model system. Using a pair of bipolar neurons in the nematode
Caenorhabditis elegans
, we found that distinct sets of intracellular molecules are required for neurite extension toward the anterior and the posterior. Moreover, signaling pathways that promote neurite extension in different directions antagonize each other to achieve balanced growth. Therefore, our study offers an in vivo example for a long-standing concept that spatially selective activation of intracellular signaling molecules could enable a diverse range of neuronal growth patterns.
Resumptivity and two types of A′‑dependencies in the Minimalist Program
Authors: Pan Victor Junnan
Published: June 2016

This paper examines the derivation of two types of A′-dependencies — relative clauses and Left-Dislocation structures — in the framework of Minimalist Program based on Mandarin data. Relatives and LD structures demonstrate many distinct syntactic and semantic properties when they contain a gap and a resumptive pronoun respectively. A thorough study of the relevant data reveals that when a gap strategy is adopted, island effects and crossover effects are always observed, irrespective of whether the relevant gap is embedded within a relative clause or within an LD structure; on the contrary, when the resumptive strategy is adopted, a sharp distinction is observed between these two structures. A resumptive relative clause gives rise to island effects and crossover effects systematically; by contrast, a resumptive LD structure never gives rise to these effects. In the Minimalist Program, island effects and crossover effects are not exclusively used as diagnostic tests for movement since the operationAgreeis also subject to locality constraints. I will argue that a relative clause containing either a gap or an RP and an LD structure with gap are derived byAgreeand they are subject to the locality condition whereas a resumptive LD structure is derived byMatchthat is an island free operation and it is not subject to the locality constraint. MultipleTransferand multiple Spell-Out are possible in anAgreechain, but not in aMatchingchain. The choice of the derivational mechanism depends on the interpretability of the formal features attached to the Probe and to the Goal in the relevant A′-dependencies.
代表属性: 发音人的选择和语料有效性 [Parameters of representativeness: Subject selection and data integrity]
Authors: Liang Yuan , Wee Lian-Hee
Published: June 2016

As an empirical study, linguistic investigations rely heavily on the selection of suitable subject speakers as representatives of a language community, which in turn underline the necessity of determining representativeness. Through explicit description of the parameters that define a target population, this paper argues that (i) representativeness can be most straightforwardly captured using the same parametric description; and (ii) the degree of representativeness of the subject increases with the degree of satisfaction of the parameters. On this footing, this paper exemplifies the fundamental quality of the parameters of representativeness across different linguistic research topics, purposes and even methodologies. Evidently, the clarification on what counts as representative through the use of parametric description is a founding stone to ensuring reliability of language data in the establishment of any linguistic theorizing.
The evolution of the “hot news” perfect in English
Authors: Yao Xinyue
Published: June 2016

This paper deals with the “hot news” use of the English present perfect. Previous research has suggested that this use marks the end point of the perfect category, paving the way for further grammaticalisation to a perfective or past tense. To examine its historical development in Modern English, verb forms in the leads of hard news reports in theNew York Timesand theSydney Morning Heraldwere examined, with comparison made between two time periods, 1851–1900 and 1951–2000. Attention was given to contextual influence on the choice between the present perfect and the past tense for expressing hot news meanings. The quantitative findings show that the hot news perfect has not taken over the ground of other tense forms, but has become increasingly associated with unspecified, recent past time. The evolution of the English present perfect in general is characterised by register-mediated functional specialisation.
The carnival is not over: Cultural resistance in dementia care
Authors: Capstick Andrea , Chatwin John
Published: June 2016

Within the still-dominant medical discourse on dementia, disorders of language feature prominently among diagnostic criteria. In this view, changes in ability to produce or understand coherent speech are considered to be an inevitable result of neuropathology. Alternative psychosocial accounts of communicative challenges in dementia exists, but to date, little emphasis has been placed on people with dementia as social actors who create meaning and context from their social interactions. In this article we draw on Bakhtin’s concepts of the carnivalesque, heteroglossia, polyphony and dialogism to analyse a series of interactions involving people with dementia in day and residential care environments. We argue that many of the communicative challenges faced by people with dementia arise from the social environments in which they find themselves, and that the utterances of people with dementia in the face of these social challenges show many of the hallmarks of cultural resistance identified by Bakhtin.
The International Classification of Disability, Functioning and Health (ICF)
Authors: Rasmussen Gitte
Published: June 2016

University of Southern Denmark
Microstructural evolution study of severely deformed commercial aluminium by transmission Kikuchi diffraction
Authors: Naghdy S. , Percq L. L. , Serret R. , Petrov R. , Hertelé S. , Kestens L. , Verleysen P.
Published: June 2016

Commercially pure aluminium was selected as a model fcc material for a detailed investigation of the microstructural and textural evolution during processing by high pressure torsion (HPT). Vickers hardness measurements reveal that: the hardness is the lowest where the lowest strain is imposed and increases with increasing strain until saturation hardness is obtained. The microstructural evolution is investigated by means of electron backscattered diffraction and transmission Kikuchi diffraction. During HPT a grain fragmentation process takes place: within the original grains dislocations aggregate, resulting in the creation of very fine grains separated first by low and later by high angle grain boundaries. At a strain level of [Formula: see text] a simple shear texture of fcc structure was observed.

This paper is part of a Themed Issue on Aluminium-based materials: processing, microstructure, properties, and recycling.
Properties of CdS films doped with magnesium and fluorine
Authors: Sivaraman T. , Nagarethinam V. S. , Balu A. R.
Published: June 2016

Nanostructured CdS thin films co-doped with Mg and F were prepared on glass substrates maintained at 400°C by spray technique using perfume atomiser. Structural, morphological, optical and electrical properties of the films were investigated in order to study the effect of Mg, F doping concentration. XRD patterns confirm that both undoped and co-doped CdS films exhibit hexagonal crystal structure with preferential orientation along the (0 0 2) plane. Crystallite size decreased from 33.19 to 24.51 nm with increase in Mg, F concentration. Increased transparency and blue shift in optical band gap from 2.48 to 2.75 eV is observed with increase in Mg, F concentration. All the films have resistivity in the order of 10−2 Ω cm which decreased with co-doping. Improved optical transparency, widened band gap and decreased resistivity were observed for the CdS films simultaneously doped with Mg and F.