bluuebunny/crossref_metadata_2025 huggingface dataset:
Signature of structural distortion in optical spectra of YFe2O4 thin film
Authors: Rai R. C. , Hinz J. , Petronilo G. X. A. , Sun F. , Zeng H. , Nakarmi M. L. , Niraula P. R.
Published: February 2016

We report structural, optical, and electro-optical properties of polycrystalline YFe2O4 thin films, deposited on (0001) sapphire substrates using the electron-beam deposition technique. The optical spectra of a 120 nm YFe2O4 show Fe d to d on-site and O 2p to Fe 3d, Y 4d, and Y 5s charge-transfer electronic excitations. Anomalies in the temperature dependence data of the charge-transfer excitations and the splitting of the 4.46 eV charge-transfer peak strongly suggest a structural distortion at 180 ± 10 K. Evidence of such a structural distortion is also manifested in the surface resistance versus temperature data. In addition, the YFe2O4 thin film at low temperatures shows strong electro-optical properties, as high as 9% in the energy range of 1 - 2.5 eV, for applied electric fields up to 500 V.cm−1.
Energy harvesting in a quad-stable harvester subjected to random excitation
Authors: Zhou Zhi-yong , Qin Wei-yang , Zhu Pei
Published: February 2016

In response to the defects of bi-stable energy harvester (BEH), we develop a novel quad-stable energy harvester (QEH) to improve harvesting efficiency. The device is made up of a bimorph cantilever beam having a tip magnet and three external fixed magnets. By adjusting the positions of the fixed magnets and the distances between the tip magnet and the fixed ones, the quad-stable equilibrium positions can emerge. The potential energy shows that the barriers of the QEH are lower than those of the BEH for the same separation distance. Experiment results reveal that the QEH can realize snap-through easier and make a dense snap-through in response under random excitation. Moreover, its strain and voltage both become large for snap-through between the nonadjacent stable positions. There exists an optimal separation distance for different excitation intensities.
Anomalous magnetism of superconducting Mg-doped InN film
Authors: Chang P. H. , Hong S. Y. , Lin W. T. , Guo Y. X.
Published: February 2016

We report on the Meissner effect of Mg-doped InN film with superconducting transition onset temperature Tc,onset of 5 K. Mg-doped InN is magnetically ordered and exhibits a simultaneous first-order magnetic and electric transition near 50 K. Its behavior is similar to that of iron-based superconductors. A strong correlation is proposed to exist between structural distortion and superconductivity when Mg is doped into InN. The suppression of magnetic ordering close to Tc by doping is further demonstrated by anisotropic magnetoresistance and M-H measurements. The findings suggest that the superconducting mechanism in the system may not be conventional BCS.
Solution processed Cu2SnS3 thin films for visible and infrared photodetector applications
Authors: Dias Sandra , Krupanidhi S. B.
Published: February 2016

The Cu2SnS3 thin films were deposited using an economic, solution processible, spin coating technique. The films were found to possess a tetragonal crystal structure using X-ray diffraction. The film morphology and the particle size were determined using scanning electron microscopy. The various planes in the crystal were observed using transmission electron microscopy. The optimum band gap of 1.23 eV and a high absorption coefficient of 104 cm−1 corroborate its application as a photoactive material. The visible and infrared (IR) photo response was studied for various illumination intensities. The current increased by one order from a dark current of 0.31 μA to a current of 1.78 μA at 1.05 suns and 8.7 μA under 477.7 mW/cm2 IR illumination intensity, at 3 V applied bias. The responsivity, sensitivity, external quantum efficiency and specific detectivity were found to be 10.93 mA/W, 5.74, 2.47% and 3.47 × 1010 Jones respectively at 1.05 suns and 16.32 mA/W, 27.16, 2.53% and 5.10 × 1010 Jones respectively at 477.7 mW/cm2 IR illumination. The transient photoresponse was measured both for visible and IR illuminations.
Current pulse shaping of the load current on PTS
Authors: Xia Minghe , Li Fengping , Ji Ce , Wei Bing , Feng Shuping , Wang Meng , Xie Weiping
Published: February 2016

The typical rise time of PTS machine is ∼110 ns with about 10 MA peak current under short pulse mode when all 24 modules discharge simultaneously. By distributing the trigger times of 12 laser beams logically and adjusting the statues of the pulse output switches, longer rise-time pulse can be obtained on the PTS facility. Based on the required pulse shape, whole circuit simulations will be used to calculate the trigger times of each laser triggering gas switch and the status of the pulse output switches. The rise time of the current is determined by the time difference between the first and last trigged laser triggering gas switches. In order to trigger the laser triggering gas switch, sufficient laser power is needed to be sent into the gap of the gas switches. The gas pressure and voltage difference on the two electrodes of the gas switches also affect the triggering of the gas switches, and the voltage added on the gas switch is determined by its transition time. Traditionally the trigger time difference should be less than the transition time of the two neighboring modules. A new simulation model of PTS shows one can break this transition time limits. Series of current pulse shaping experiments have been investigated on the PTS (Primary Test Stand). As results, more than 5 MA peak current were successfully achieved on the load with a rise time of 600 ns. This study and experiments of the pulse shaping on PTS demonstrate the adaptable ability of the PTS for offering different waveform of mega ampere current pulse for different research purpose.
Research on aluminum alloy sheet thermoplastic deformation behavior based upon warm bulging test
Authors: Cai Gaoshen , Zhou Xiaojun , Lang Lihui , Alexandrov Sergei
Published: February 2016

The rate of fluid pressure variation is a crucial factor to indicate the forming speed and the pressure rate is applied to be one factor that can influence the deformation of material in warm sheet hydroforming. In this study, warm bulging test was conducted to obtain bulging pressure-height curves with different temperatures and pressure rates. Fitting the bulging pressure-equivalent strain curves obtained using bulging test with surface fitting method, the fitted equation of bulging pressure on equivalent strain and pressure rate was achieved, and the fitting result shows a good accordance with experimental and calculated values. Then, the relation between pressure rate and strain rate was obtained. The results of warm bulging test indicated that the deformation behavior of metal material is sensitive to pressure rate, which is of great significance for warm sheet hydroforming.
From zirconia to yttria: Sampling the YSZ phase diagram using sputter-deposited thin films
Authors: Götsch Thomas , Wallisch Wolfgang , Stöger-Pollach Michael , Klötzer Bernhard , Penner Simon
Published: February 2016

Yttria-stabilized zirconia (YSZ) thin films with varying composition between 3 mol% and 40 mol% have been prepared by direct-current ion beam sputtering at a substrate temperature of 300 °C, with ideal transfer of the stoichiometry from the target to the thin film and a high degree of homogeneity, as determined by X-ray photoelectron and energy-dispersive X-ray spectroscopy. The films were analyzed using transmission electron microscopy, revealing that, while the films with 8 mol% and 20 mol% yttria retain their crystal structure from the bulk compound (tetragonal and cubic, respectively), those with 3 mol% and 40 mol% Y2O3 undergo a phase transition upon sputtering (from a tetragonal/monoclinic mixture to purely tetragonal YSZ, and from a rhombohedral structure to a cubic one, respectively). Selected area electron diffraction shows a strong texturing for the three samples with lower yttria-content, while the one with 40 mol% Y2O3 is fully disordered, owing to the phase transition. Additionally, AFM topology images show somewhat similar structures up to 20 mol% yttria, while the specimen with the highest amount of dopant features a lower roughness. In order to facilitate the discussion of the phases present for each sample, a thorough review of previously published phase diagrams is presented.
High sensitivity zero-biased magnetic field sensor based on multiphase laminate heterostructures with FeCuNbSiB nanocrystalline soft magnetic alloy
Authors: Qiu Jing , Wen Yumei , Li Ping , Chen Hengjia
Published: February 2016

In this paper, a high sensitivity zero-biased magnetic field sensor based on multiphase laminate heterostructures consisting of FeCuNbSiB/Terfenol-D (Tb1−xDyxFe2)/PZT (Pb(Zr1-x,Tix)O3)/Terfenol-D/PZT/Ternol-D/FeCuNbSiB (FMPMPMF) is presented, whose ME coupling characteristics and sensing performances have been investigated. Compared to traditional Terfenol-D/PZT/Terfenol-D (MPM) and Terfenol-D/PZT/Terfenol-D/PZT/Terfenol-D (MPMPM) sensors, the zero-biased ME coupling characteristics of FMPMPMF sensor were significantly improved, owing to a build-in magnetic field in FeCuNbSiB/Terfenol-D layers. The optimum zero-biased resonant ME voltage coefficient of 3.02 V/Oe is achieved, which is 1.65 times as great as that of MPMPM and 2.51 times of MPM sensors. The mean value of low-frequency ME field coefficient of FMPMPMF reaches 122.53 mV/cm Oe, which is 2.39 times as great as that of MPMPM and 1.79 times of MPM sensors. Meanwhile, the induced zero-biased ME voltage of FMPMPMF sensor shows an excellent linear relationship to ac magnetic field both at the low frequency (1 kHz) and the resonant frequency (106.6 kHz). Remarkably, it indicates that the proposed zero-biased magnetic field sensor give the prospect of being able to applied to the field of highly sensitive ac magnetic field sensing.
Topological phase transition of a fractal spin system: The relevance of the network complexity
Authors: Torres Felipe , Rogan José , Kiwi Miguel , Valdivia Juan Alejandro
Published: February 2016

A new type of collective excitations, due to the topology of a complex random network that can be characterized by a fractal dimension DF, is investigated. We show analytically that these excitations generate phase transitions due to the non-periodic topology of the DF > 1 complex network. An Ising system, with long range interactions, is studied in detail to support the claim. The analytic treatment is possible because the evaluation of the partition function can be decomposed into closed factor loops, in spite of the architectural complexity. The removal of the infrared divergences leads to an unconventional phase transition, with spin correlations that are robust against thermal fluctuations.
Reaching sentence and reference meaning
Authors: Engelhardt Paul E. , Ferreira Fernanda L.
Published: February 2016

This chapter focuses on how people establish reference to objects in the external world and the meaning of sentences more broadly. The review proceeds from psychological and computational models of semantic memory up to how people establish reference to particular objects in the environment via pre- and post-nominal (linguistic) modification. We also briefly touch upon the interpretation of events and enriched composition. A distinction is drawn between meaning activation pre-lexical access and meaning activation that results from the combinatorial process of integrating multiple words together into structured constituents and phrases. Many of the reviewed studies used the Visual World Paradigm, and thus, eye movements are the primary outcome measure.
Discourse level processing
Authors: Kaiser Elsi
Published: February 2016

This chapter provides an overview of how the visual-world eye-tracking paradigm has been used to investigate the processing and representation of discourse-level information. The chapter starts by reviewing some theoretical approaches to information structure, and then turns to visual-world experiments on the prosodic and syntactic reflexes of information structure, as well as the consequences of information structure for reference resolution. The notion of ‘prominence’ plays a central role in many of these investigations, in the shape of prosodic prominence (associated with new information), syntactic prominence (often associated with given or topical information) and representational prominence / accessibility in the domain of reference resolution. Comprehenders use prominence-related information to guide discourse-level aspects of processing, but prosodic prominence and syntactic prominence have different information-structural correlates. Furthermore, if we want to conceptualize reference resolution as a process sensitive to the prominence of mental representations, our view of what factors influence referential prominence needs to include not only entity-related factors (e.g. givenness), but also event-related factors (e.g. verb semantics and coherence relations between events). As a whole, the findings discussed in this chapter highlight the rapidity with which the human language processing system uses of discourse-level information, whether it be encoded in pitch accents, word order or the form of referring expressions. These findings suggest that discourse-level comprehension should not be relegated to a secondary stage of processing and instead occurs in tandem with other aspects of language comprehension, such as lexical access and syntactic processing.
Figurative language processing
Authors: Huette Stephanie , Matlock Teenie
Published: February 2016

This chapter is concerned with visual processing in the context of figurative language. Included is background on research that has used the visual world paradigm to study the processing of fictive motion sentences. These sentences, which are ubiquitous in everyday language, include a motion verb but describe no motion (e.g., “A road goes through the desert”, “The cord runs along the wall”). Also included is discussion of emerging concepts that form novel hypotheses for how figurative language is processed. This chapter grounds fictive motion processing in interactive dynamical systems and takes figurative language in a new direction.
Visual environment and interlocutors in situated dialogue
Authors: Brown-Schmidt Sarah
Published: February 2016

Face-to-face conversation is often considered the most basic form of language use, as it was likely a dominant mode of communication as languages evolved, it is often the primary form of language input during children’s language acquisition, and it is a dominant mode of adult communication today. Conversational language differs in important ways from the language traditionally studied in psycholinguistics; thus, characterizing language processing in conversation is essential if models of language understanding are to extend to this most basic form of language use. This chapter will examine key features of language comprehension in conversation, and will highlight the role of the visual environment in establishing joint domains of reference. Unlike in non-interactive settings, in conversation language is jointly created by conversational partners who hold different, but partially overlapping representations of the relevant context. Understanding if and how partners appreciate their partner’s perspective has emerged as a central question in this domain.
The use of photographs as historical sources, a case study
Authors: Baigorri-Jalón Jesús
Published: February 2016

This chapter presents a case study of how photographs can offer different angles
of the dynamics involved in a complex observable event or series of events. As
shown in previous research, photographs can only be valid historical sources if
we are able to interpret them, and that requires the observer’s active participation
and the use of additional sources, such as written or oral records. I analyze
eight United Nations (UN) official photographs as part of the founding narrative
of simultaneous interpreting (SI) history. After introducing the theoretical
and methodological background, I present the historical context of SI at the
UN. The analysis of the photographs focuses on (1) the SI equipment, (2) the
interpreters, and (3) the users of their services.
Guilt, survival, opportunities, and stigma
Authors: Takeda Kayoko
Published: February 2016

Following the end of World War II, Japanese interpreters faced unique and
complex opportunities and hardships. In occupied Japan, thousands of local
interpreters (and translators) were recruited to assist in a variety of occupation operations led by
the US forces. In war crimes trials, Japanese linguists played an important role
as interpreters in court proceedings against their former superiors and compatriots.
At the same time, some interpreters who had served in the Japanese
Army were prosecuted as war criminals. Wartime interpreters were also tapped
as witnesses to testify for the prosecution during trials. These
diverse experiences of Japanese interpreters during the occupation period shine
light on some issues and risks faced by wartime interpreters and local interpreters
serving foreign military occupiers.
The verbal form V-ā in Hindi/Urdu
Authors: Montaut Annie
Published: February 2016

Although the term aorist has not been frequently used in the various grammars of Hindi, and the current label for the simple past is now “perfective”, the simple form used for the narrative past has a unique position within the global TAM system, as well as in the indicative paradigm. It displays the standard meanings usually associated to the aorist, and some of its specific meanings can help better describe this linguistic category. Distinct both from the perfective and from the perfect, it conveys the aspectual and temporal meaning of an anterior event, of eventual, gnomic present, anticipation, treated in the study within a topological and enunciative frame. The historical evolution of the verbal paradigm partially accounts for its present form and function; it also explains why it has come to convey mirative meanings, rather than the perfect.
No escape from the future
Authors: Vapnarsky Valentina
Published: February 2016

This article deals with debated questions on the semantics and cognition of temporality: the existence of tenseless languages, the cultural variability of the representation of the future and the plurality of temporal frames and its contextdependency. It explores the hypothesis that even in tenseless languages, inferences relative to temporal location may ultimately become conventionalized and encoded by grammatical markers. While futurity is generally taken as the least tensy of tenses, this hypothesis is proposed for a future marker in Yucatec Maya (bíin). Features of factuality, remoteness and dissociation from the contemporal domain are further analysed, and lead to a characterization of bíin as triggering a non-actualized temporal frame of reference, associated with the domain of predetermined events outside human control.
Chapter 11. From Diacritics to the Mental Lexicon
Authors: Protopapas Athanassios
Published: February 2016

This chapter presents recent work on stress assignment in reading Greek, aiming to help understand the cognitive processes of reading and the representation of words in the mental lexicon. Word spelling and pseudoword reading studies spanning a wide range from early grades through adulthood have suggested a developmentally limited role for the processing of the obligatory stress diacritic. Children with reading difficulties are especially impaired in explicit stress assignment tasks involving pseudowords. Considered alongside stress priming experiments, these studies suggest that stress information is primarily derived from the lexicon and that it is associated with specific words rather than represented generically in the form of abstract templates. Further research is needed to elucidate stress representations and stress assignment processes.
The 1D Kardar–Parisi–Zhang equation: Height distribution and universality
Authors: Sasamoto Tomohiro
Published: February 2016

The Kardar–Parisi–Zhang (KPZ) equation, which was introduced in 1986 as a model equation to describe the dynamics of an interface motion, has been attracting renewed interest in recent years. In particular, the height distribution of its 1D version was determined exactly for a few special initial conditions. Its relevance in experiments was demonstrated and our understanding of the mathematical structures behind its tractability has deepened considerably. There are also new developments in the applicability of the KPZ universality in wider contexts. This paper is a short introductory review on the basics of the equation and on a few recent topics.
Noncoding RNAs of Plant Viruses and Viroids: Sponges of Host Translation and RNA Interference Machinery
Authors: Miller W. Allen , Shen Ruizhong , Staplin William , Kanodia Pulkit
Published: February 2016

Noncoding sequences in plant viral genomes are well-known to control viral replication and gene expression in cis. However, plant viral and viroid noncoding (nc)RNA sequences can also regulate gene expression acting in trans, often acting like ‘sponges’ that bind and sequester host cellular machinery to favor viral infection. Noncoding sequences of small subgenomic (sg)RNAs of Barley yellow dwarf virus (BYDV) and Red clover necrotic mosaic virus (RCNMV) contain a cap-independent translation element that binds translation initiation factor eIF4G. We provide new evidence that a sgRNA of BYDV can globally attenuate host translation, probably by sponging eIF4G. Subgenomic ncRNA of RCNMV is generated via 5′ to 3′ degradation by a host exonuclease. The similar noncoding subgenomic flavivirus (sf)RNA, inhibits the innate immune response, enhancing viral pathogenesis. Cauliflower mosaic virus transcribes massive amounts of a 600-nt ncRNA, which is processed into small RNAs that overwhelm the host’s RNA interference (RNAi) system. Viroids use the host RNAi machinery to generate viroid-derived ncRNAs that inhibit expression of host defense genes by mimicking a microRNA. More examples of plant viral and viroid ncRNAs are likely to be discovered, revealing fascinating new weaponry in the host-virus arms race.
Evolution of HIV virulence in response to widespread scale up of antiretroviral therapy: a modeling study
Authors: Herbeck Joshua , Mittler John E. , Gottlieb Geoffrey S. , Goodreau Steven , Murphy James T. , Cori Anne , Pickles Michael , Fraser Christophe
Published: February 2016

There are global increases in the use of HIV antiretroviral therapy (ART), guided by clinical benefits of early ART initiation, and the efficacy of treatment as prevention of transmission. Separately, it has been shown theoretically and empirically that HIV virulence can evolve over time. Observed virulence levels may reflect an adaptive balance between infected lifespan and per-contact transmission rate. Critically, the potential effects of widespread ART on HIV virulence are unknown. To predict these effects, we used an agent-based stochastic model to simulate changes in HIV virulence, using set point viral load as a virulence proxy. We calibrated our epidemic model to the prevalence and incidence trends of South Africa. We repeated our analysis using a separate calibration, as a sensitivity analysis, and found that predicted impact of ART on virulence was relatively insensitive to calibration. We explored two ART scenarios, at increasing coverage : ART initiation based on patients reaching a CD4 cell count threshold, or based on time elapsed since infection (a scenario that mimics the “universal testing and treatment” aspirations). We found that HIV virulence is generally unchanged in scenarios of CD4-based initiation. However, with ART initiation based on time since infection, virulence can increase moderately within several years of ART rollout, under high coverage and early treatment initiation, albeit within the context of rapidly shrinking epidemics. Our modeling study suggests that increasing virulence driven by universal test and treat is likely not a major public health concern, but could be monitored in sentinel surveillance, in a manner similar to transmitted drug resistance.
Identifying Network Perturbation in Cancer
Authors: Grechkin Maxim , Logsdon Benjamin , Gentles Andrew , Lee Su-In
Published: February 2016

We present a computational framework, called DISCERN (DIfferentialSparsE RegulatoryNetwork), to identify informative topological changes in gene-regulator dependence networks inferred on the basis of mRNA expression datasets within distinct biological states. DISCERN takes two expression datasets as input: an expression dataset of diseased tissues from patients with a disease of interest and another expression dataset from matching normal tissues. DISCERN estimates the extent to which each gene isperturbed– having distinct regulator connectivity in the inferred gene-regulatory dependencies between the disease and normal conditions. This approach has distinct advantages over existing methods. First, DISCERN infersconditional dependenciesbetween candidate regulators and genes, where conditional dependence relationships discriminate the evidence for direct interactions from indirect interactions more precisely than pairwise correlation. Second, DISCERN uses a new likelihood-based scoring function to alleviate concerns about accuracy of the specific edges inferred in a particular network. DISCERN identifies perturbed genes more accurately in synthetic data than existing methods to identify perturbed genes between distinct states. In expression datasets from patients with acute myeloid leukemia (AML), breast cancer and lung cancer, genes with high DISCERN scores in each cancer are enriched for known tumor drivers, genes associated with the biological processes known to be important in the disease, and genes associated with patient prognosis, in the respective cancer. Finally, we show that DISCERN can uncover potential mechanisms underlying network perturbation by explaining observed epigenomic activity patterns in cancer and normal tissue types more accurately than alternative methods, based on the available epigenomic from the ENCODE project.
Enabling the democratization of the genomics revolution with a fully integrated web-based bioinformatics platform
Authors: Li Po-E , Lo Chien-Chi , Anderson Joseph J. , Davenport Karen W. , Bishop-Lilly Kimberly A. , Xu Yan , Ahmed Sanaa , Feng Shihai , Mokashi Vishwesh P. , Chain Patrick S. G.
Published: February 2016

Continued advancements in sequencing technologies have fueled the development of new sequencing applications and promise to flood current databases with raw data. A number of factors prevent the seamless and easy use of these data, including the breadth of project goals, the wide array of tools that individually perform fractions of any given analysis, the large number of associated software/hardware dependencies, and the detailed expertise required to perform these analyses. To address these issues, we have developed an intuitive web-based environment with a wide assortment of integrated and cutting-edge bioinformatics tools. These preconfigured workflows provide even novice next-generation sequencing users with the ability to perform many complex analyses with only a few mouse clicks, and, within the context of the same environment, to visualize and further interrogate their results. This bioinformatics platform is an initial attempt at Empowering the Development of Genomics Expertise (EDGE) in a wide range of applications.
Microarray analysis identifies malignant field signatures in biopsy samples at diagnosis predicting the likelihood of lethal disease in patients with localized Gleason 6 and 7 prostate cancer
Authors: Glinsky Gennadi V.
Published: February 2016

Overtreatment of early-stage low-risk prostate cancer patients represents a significant problem in disease management and has significant socio-economic implications. Development of genetic and molecular markers of clinically significant disease in patients diagnosed with low grade localized prostate cancer would have a major impact in disease management. A gene expression signature (GES) is reported for lethal prostate cancer in biopsy specimens obtained at the time of diagnosis from patients with Gleason 6 and Gleason 7 tumors in a Swedish watchful waiting cohort with up to 30 years follow-up. A 98-genes GES identified 89% and 100% of all death events 4 years after diagnosis in Gleason 7 and Gleason 6 patients, respectively; at 6 years follow-up, 83% and 100% of all deaths events were captured in Gleason 7 and Gleason 6 patients, respectively. Remarkably, the 98-genes GES appears to perform successfully in patients stratification with as little as 2% of cancer cells in a specimen, strongly indicating that it captures a malignant field effect in human prostates harboring cancer cells of different degrees of aggressiveness. In Gleason 6 and Gleason 7 tumors from prostate cancer patients of age 65 or younger, GES identified 86% of all death events during the entire follow-up period. In Gleason 6 and Gleason 7 tumors from prostate cancer patients of age 70 or younger, GES identified 90% of all death events 6 years after diagnosis. Classification performance of the reported in this study 98-genes GES of lethal prostate cancer appeared suitable to meet design and feasibility requirements of a prospective 4 to 6 years clinical trial, which is essential for regulatory approval of diagnostic and prognostic tests in clinical setting. Prospectively validated GES of lethal PC in biopsy specimens of Gleason 6 and Gleason 7 tumors will help physicians to identify, at the time of diagnosis, patients who should be considered for exclusion from active surveillance programs and who would most likely benefit from immediate curative interventions.
A trait‐mediated, neighbourhood approach to quantify climate impacts on successional dynamics of tropical rainforests
Authors: Uriarte María , Lasky Jesse R. , Boukili Vanessa K. , Chazdon Robin L.
Published: February 2016

Second‐growth forests account for 40% of the terrestrial forest carbon sink and represent the dominant forest cover in tropical regions. Uncertainties in predicting responses of these ecosystems to climate change arise from high tree species diversity, complex links between eco‐physiology and demography, and the role of ontogeny and competition in mediating individual tree responses to climate. The dynamic nature of second‐growth forests adds further uncertainty to our ability to quantify the relative importance of climate in mediating successional trajectories.

To address these uncertainties, we develop a hierarchical Bayesian neighbourhood modelling approach that quantifies how the joint response of two key functional axes, wood density and specific leaf area (SLA), modulate impacts of inter‐annual variation in seasonal water stress (number of days during dry season > 1 kPa vapour pressure deficit) and night‐time temperature on growth and survival of small (5–10 cm dbh) and large (≥ 10 cm dbh) trees for 171 rainforest species in 6 s‐growth and 2 old‐growth 1‐ha mapped stands. We use model results to examine potential climate impacts on the successional trajectories of these stands.

High water stress reduced large tree growth but favoured growth of small trees. Drought also reduced tree survival for both large and small trees. Tree species with high wood density suffered lower growth reductions and had higher survival under water stress. High SLA magnified the negative effects of water stress on tree growth and survival. Across all tree sizes, high night‐time temperatures did not influence growth or survival. Simulated successional trajectories under different climate scenarios using these results suggest that multi‐annual droughts will have substantial impacts of the successional trajectories of tropical forests, leading to lower stem numbers, basal area and biomass. Sustained drought will also shift functional composition of second‐growth forest by favouring species with low SLA which tend to dominate in late stages of succession.

By incorporating trait‐mediated effects on key drivers of tree demography and successional dynamics, our approach provides an integrated perspective on interspecific variation in vulnerability to drought and consequences for successional trajectories in tropical rainforests. Our results suggest that multi‐annual drought stress will significantly alter structure, composition and dynamics of second‐growth forests and, from a functional perspective, accelerate succession. However, this effect may be hampered by dispersal limitation of old‐growth species into second‐growth forests.
Functional traits as predictors of vital rates across the life cycle of tropical trees
Authors: Visser Marco D. , Bruijning Marjolein , Wright S. Joseph , Muller‐Landau Helene C. , Jongejans Eelke , Comita Liza S. , de Kroon Hans
Published: February 2016

The ‘functional traits’ of species have been heralded as promising predictors for species’ demographic rates and life history. Multiple studies have linked plant species’ demographic rates to commonly measured traits. However, predictive power is usually low – raising questions about the practical usefulness of traits – and analyses have been limited to size‐independent univariate approaches restricted to a particular life stage.

Here we directly evaluated the predictive power of multiple traits simultaneously across the entire life cycle of 136 tropical tree species from centralPanama. Using a model‐averaging approach, we related wood density, seed mass, leaf mass per area and adult stature (maximum diameter) to onset of reproduction, seed production, seedling establishment, and growth and survival at seedling, sapling and adult stages.

Three of the four traits analysed here (wood density, seed mass and adult stature) typically explained 20–60% of interspecific variation at a given vital rate and life stage. There were strong shifts in the importance of different traits throughout the life cycle of trees, with seed mass and adult stature being most important early in life, and wood density becoming most important after establishment. Every trait had opposing effects on different vital rates or at different life stages; for example, seed mass was associated with higher seedling establishment and lower initial survival, wood density with higher survival and lower growth, and adult stature with decreased juvenile but increased adult growth and survival.

Forest dynamics are driven by the combined effects of all demographic processes across the full life cycle. Application of a multitrait and full‐life cycle approach revealed the full role of key traits, and illuminated how trait effects on demography change through the life cycle. The effects of traits on one life stage or vital rate were sometimes offset by opposing effects at another stage, revealing the danger of drawing broad conclusions about functional trait–demography relationships from analysis of a single life stage or vital rate. Robust ecological and evolutionary conclusions about the roles of functional traits rely on an understanding of the relationships of traits to vital rates across all life stages.
Getting the smell of it – odour cues structure pollinator networks
Authors: Hambäck Peter A.
Published: February 2016

Floral visitors vary greatly among plant species and depend on the volatiles emitted by the flowers. Creeping thistle is normally visited by bees and bumblebees while common yarrow is rather visited by flies. Manipulating the flower volatiles caused pollinator communities to become more similar among the two plant species. Image credit: Robert Junker and Anna‐Amelie Larue.

In Focus: Larue, A.‐A.C., Raguso, R.A. & Junker, R.R. (2015) Experimental manipulation of floral scent bouquets restructures flower–visitor interactions in the field. Journal of Animal Ecology, 85, 396–408.

Pollinators use multiple cues to locate suitable flowers, and recent studies argue that flower volatiles are more important than previously believed. However, the role of volatiles is seldom separated from other cues. Larue, Raguso & Junker (2015) manipulated the volatile profile of two plants that are normally visited by different pollinators. Achillea millefolium is normally not visited by honeybees and bumblebees, but these pollinator groups did visit plants that were sprayed with volatiles from Cirsium arvense. Cirsium arvense, on the other hand, was less visited by honeybees and bumblebees when sprayed with volatiles from A. millefolium. These findings highlight the potential role of volatiles in structuring pollinator communities on plants.
Thresholds and gradients in a semi‐arid grassland: long‐term grazing treatments induce slow, continuous and reversible vegetation change
Authors: Porensky Lauren M. , Mueller Kevin E. , Augustine David J. , Derner Justin D.
Published: February 2016

Temporal changes in semi‐arid ecosystems can include transitions between alternative stable states, involving thresholds and multiple domains of attraction, but can also include relatively continuous, symmetric and reversible shifts within a single stable state. Conceptual state‐and‐transition models (STMs) describe both types of ecosystem dynamics by including state transitions (plant community changes difficult‐to‐reverse without substantial input or effort) and phase shifts (easily reversible community changes) as consequences of management practices and environmental variability. Grazing management is purported to be the primary driver of state transitions in current STMs for North American grasslands, but there is limited empirical evidence from these grasslands showing that grazing can cause difficult‐to‐reverse transitions between alternate stable states.

In a northern mixed‐grass prairie in Wyoming, USA, we examined plant community responses to (i) long‐term (33‐year) grazing intensity treatments (none, light, moderate and heavy stocking rates) and (ii) 8 years of light or no grazing in pastures that were grazed heavily for the previous 25 years.

Long‐term grazing treatments were associated with distinct, but not stable, plant communities. From year 22 to 33, heavier stocking rates decreased cover of dominant C3 grasses and increased cover of the dominant C4 grass Bouteloua gracilis.

Reversing stocking rates from heavy to light or no grazing resulted in reversal of changes induced by prior heavy stocking for dominant C3 grasses, but not for B. gracilis. For both groups, rates of change following grazing treatment reversals were consistent with rates of change during the initial years of the experiment (1982–1990).

Synthesis and applications. In a semi‐arid rangeland with a long evolutionary history of grazing, different long‐term grazing intensity treatments caused slow, continuous and directional changes with important management implications, but did not appear to induce alternative stable states. For this and similar ecosystems, quantifying the time‐scales and compositional gradients associated with key phase shifts may be more important than identifying thresholds between alternative stable states.
Contrasting effects of spatial heterogeneity and environmental stochasticity on population dynamics of a perennial wildflower
Authors: Crone Elizabeth E.
Published: February 2016

Understanding how variation in growth, survival and reproduction affect population dynamics is a fundamental question in ecology. Although the effects of among‐year variation (environmental stochasticity) are well understood, the effects of among‐site variation (spatial heterogeneity) are less clearly defined.

I evaluated the effects of spatial and temporal variation on the population dynamics of Pulsatilla patens, pasqueflower, a perennial prairie forb. I conducted a 10‐year demographic monitoring study, and quantified vital rate variation among sites and years using generalized linear models. I incorporated vital rate functions using this variation into integral projection models for stochastic and spatially heterogeneous environments.

I also explored the effects of temporal and spatial autocorrelation, by exploring model predictions over the range of possible values for temporal autocorrelation and local seed dispersal.

Vital rates varied more among years than among sites. However, environmental stochasticity and spatial heterogeneity had similar magnitude effects on population dynamics. These effects were also qualitatively different: environmental stochasticity reduced population growth rates relative to the average, whereas spatial heterogeneity increased population growth rates.

Spatial autocorrelation and negative temporal autocorrelation led to higher population growth rates, although environmental stochasticity still reduced growth rates for all autocorrelation values, and spatial heterogeneity increased growth rates for all autocorrelation values. Some form of autocorrelation would be necessary for model projections to match observed population trends.

Synthesis. Spatial heterogeneity is as important as environmental stochasticity for population dynamics, but it is much less often incorporated into population projection models. This study points to a number of interesting avenues for future research into the roles of spatial heterogeneity and spatiotemporal variation for long‐term population dynamics.
Environmental drivers of demographic variation across the global geographical range of 26 plant species
Authors: Treurnicht Martina , Pagel Jörn , Esler Karen J. , Schutte‐Vlok AnneLise , Nottebrock Henning , Kraaij Tineke , Rebelo Anthony G. , Schurr Frank M.
Published: February 2016

Understanding how rates of reproduction and survival respond to environmental variation across species’ geographical ranges is a key task for both basic and applied ecology. So far, however, environmental drivers of range‐wide demographic variation have only been studied in a few plant species without considering the potentially confounding effects of population density on demographic rates.

We present a large‐scale demographic study of 26 shrub species (Proteaceae) from the Cape Floristic Region. All study species have a fire‐dependent life cycle and are serotinous: they exclusively form a canopy seed bank which contains the seeds produced since the last fire. Fire triggers seed release from the canopy so that recruitment is largely limited to a short period after fire.

Across the global geographical ranges of the study species, we collected 3454 population‐level records of total fecundity since the last fire (size of individual canopy seed banks), per‐capita recruitment (ratio between post‐fire recruits and pre‐fire adults) and adult fire survival. We used linear regressions to quantify how climate, population density, fire interval and soil nutrients affect demographic variation.

A trade‐off between survival and reproduction is evident throughout the geographical ranges of our study species: resprouting species with fire‐protected buds had much higher fire survival than nonsprouters without fire‐protected buds (97% vs. 2%) but they also had substantially lower fecundity and recruitment rates. We found little intraspecific variation in fire survival rates but considerable intraspecific variation in fecundity and recruitment.

Range‐wide variation in fecundity was dominated by fire interval whereas recruitment was mostly climate‐driven. Population density and soil nutrients generally had smaller effects but were important for the fecundity and recruitment of several species. Effects of fire interval on fecundity were consistent across species, but other demography–environment relationships showed substantial interspecific differentiation.

Synthesis. This study extends demographic research beyond the population to cover the geographical ranges of multiple species. Such large‐scale studies are a necessary first step of a research agenda that aims to understand how range dynamics emerge from first principles of demography, how they are shaped by functional traits and macroevolution and how they will be impacted by global change.
Forest community response to invasive pathogens: the case of ash dieback in a British woodland
Authors: Needham Jessica , Merow Cory , Butt Nathalie , Malhi Yadvinder , Marthews Toby R. , Morecroft Michael , McMahon Sean M.
Published: February 2016

Large‐scale mortality events in forests are increasing in frequency and intensity and can lead to both intermediate‐ and long‐term changes in these systems. Specialist pests and pathogens are unique disturbances, as they commonly target individual species that are relatively prevalent in the community.

Understanding the consequences of pathogen‐caused mortality requires using sometimes limited available data to create statistical models that can forecast future community states.

In the last two decades, ash dieback disease has swept through Europe causing widespread mortality ofFraxinus excelsiorL. (European ash) across much of its distribution. In theUK,F. excelsioris an abundant and ecologically important species.

Using demographic data from an 18 ha plot in Wytham Woods, Oxfordshire, we built models that forecast the response of this forest plot to the loss ofF. excelsior. We combine integral projection models and individual‐based models to link models of growth, survival and fecundity to population dynamics. We demonstrate likely responses in Wytham by comparing projections under different levels ofF. excelsiormortality. To extrapolate results to other systems, we test hypotheses regarding the role of abundance, spatial structure and demographic differences between species in determining community response to disease disturbance.

We show that the outcome of succession is determined largely by the differing demographic strategies and starting abundances of competing species. Spatial associations between species were shown to have little effect on community dynamics at the spatial scale of this plot.

Synthesis. Host‐specific pests and pathogens are an increasingly important type of disturbance. We have developed a framework that makes use of forest inventory data to forecast changes in the population dynamics of remaining species and the consequences for community structure. We use our framework to predict how a typical British woodland will respond to ash dieback disease and show how vital rates, spatial structure and abundance impact the community response to the loss of a key species.
Global coherence during discourse production in adults: a review of the literature
Authors: Ellis Charles , Henderson Amy , Wright Heather Harris , Rogalski Yvonne
Published: February 2016

Background

Global coherence is a metric of expressive language performance that represents the speaker's ability to initiate, plan and maintain a topic of discussion. Studies indicate that disruptions of global coherence can occur during the ageing process and following neurological disease or injury. However, little is known about the specific impact that the ageing process, disease or injury has on global coherence during discourse production.

Aims

To review the literature on global coherence in adult populations and assess the impact that age, disease or injury has on global coherence during expressive language tasks.

Methods & Procedures

We completed an in‐depth search of Medline and PyschInfo (1990–2014) to identify studies of global coherence in adult populations. We identified studies that included a comparison group and utilized a measure of global coherence during expressive language production among adults.

Outcomes & Results

Twenty studies comprised of 692 study participants who met inclusion criteria were identified for the review of the literature. Studies included participants without neurological impairments and individuals with aphasia, traumatic brain injury, dementia, generalized memory impairment and other neurological conditions. Study results indicated global coherence is an expressive language skill that is influenced by the ageing process and neurological disease or injury.

Conclusions & Implications

Although evidence indicated that global coherence is negatively influenced by ageing and neurological disease/injury, the heterogeneity of study populations, measurement tools and study designs were limiting factors in determining the exact nature by which these factors impact the skill of global coherence.