bluuebunny/crossref_metadata_2025_split huggingface dataset:
The spectral and chemical measurement of pollutants on snow near South Pole, Antarctica
Authors: Casey K. A. , Kaspari S. D. , Skiles S. M. , Kreutz K. , Handley M. J. 
Published: May 2017

AbstractRemote sensing of light‐absorbing particles (LAPs), or dark colored impurities, such as black carbon (BC) and dust on snow, is a key remaining challenge in cryospheric surface characterization and application to snow, ice, and climate models. We present a quantitative data set of in situ snow reflectance, measured and modeled albedo, and BC and trace element concentrations from clean to heavily fossil fuel emission contaminated snow near South Pole, Antarctica. Over 380 snow reflectance spectra (350–2500 nm) and 28 surface snow samples were collected at seven distinct sites in the austral summer season of 2014–2015. Snow samples were analyzed for BC concentration via a single particle soot photometer and for trace element concentration via an inductively coupled plasma mass spectrometer. Snow impurity concentrations ranged from 0.14 to 7000 part per billion (ppb) BC, 9.5 to 1200 ppb sulfur, 0.19 to 660 ppb iron, 0.013 to 1.9 ppb chromium, 0.13 to 120 ppb copper, 0.63 to 6.3 ppb zinc, 0.45 to 82 parts per trillion (ppt) arsenic, 0.0028 to 6.1 ppb cadmium, 0.062 to 22 ppb barium, and 0.0044 to 6.2 ppb lead. Broadband visible to shortwave infrared albedo ranged from 0.85 in pristine snow to 0.62 in contaminated snow. LAP radiative forcing, the enhanced surface absorption due to BC and trace elements, spanned from <1 W m−2 for clean snow to ~70 W m−2 for snow with high BC and trace element content. Measured snow reflectance differed from modeled snow albedo due to specific impurity‐dependent absorption features, which we recommend be further studied and improved in snow albedo models.
A new unconditionally stable and consistent quasi‐analytical in‐stream water quality solution scheme for CSTR‐based water quality simulators
Authors: Woldegiorgis Befekadu Taddesse , van Griensven Ann , Pereira Fernando , Bauwens Willy 
Published: May 2017

AbstractMost common numerical solutions used in CSTR‐based in‐stream water quality simulators are susceptible to instabilities and/or solution inconsistencies. Usually, they cope with instability problems by adopting computationally expensive small time steps. However, some simulators use fixed computation time steps and hence do not have the flexibility to do so. This paper presents a novel quasi‐analytical solution for CSTR‐based water quality simulators of an unsteady system. The robustness of the new method is compared with the commonly used fourth‐order Runge‐Kutta methods, the Euler method and three versions of the SWAT model (SWAT2012, SWAT‐TCEQ, and ESWAT). The performance of each method is tested for different hypothetical experiments. Besides the hypothetical data, a real case study is used for comparison. The growth factors we derived as stability measures for the different methods and the R‐factor—considered as a consistency measure—turned out to be very useful for determining the most robust method. The new method outperformed all the numerical methods used in the hypothetical comparisons. The application for the Zenne River (Belgium) shows that the new method provides stable and consistent BOD simulations whereas the SWAT2012 model is shown to be unstable for the standard daily computation time step. The new method unconditionally simulates robust solutions. Therefore, it is a reliable scheme for CSTR‐based water quality simulators that use first‐order reaction formulations.
Biofilm‐induced bioclogging produces sharp interfaces in hyporheic flow, redox conditions, and microbial community structure
Authors: Caruso Alice , Boano Fulvio , Ridolfi Luca , Chopp David L. , Packman Aaron 
Published: May 2017

AbstractRiverbed sediments host important biogeochemical processes that play a key role in nutrient dynamics. Sedimentary nutrient transformations are mediated by bacteria in the form of attached biofilms. The influence of microbial metabolic activity on the hydrochemical conditions within the hyporheic zone is poorly understood. We present a hydrobiogeochemical model to assess how the growth of heterotrophic and autotrophic biomass affects the transport and transformation of dissolved nitrogen compounds in bed form‐induced hyporheic zones. Coupling between hyporheic exchange, nitrogen metabolism, and biomass growth leads to an equilibrium between permeability reduction and microbial metabolism that yields shallow hyporheic flows in a region with low permeability and high rates of microbial metabolism near the stream‐sediment interface. The results show that the bioclogging caused by microbial growth can constrain rates and patterns of hyporheic fluxes and microbial transformation rate in many streams.
Modeling the climate impacts of deploying solar reflective cool pavements in California cities
Authors: Mohegh Arash , Rosado Pablo , Jin Ling , Millstein Dev , Levinson Ronnen , Ban‐Weiss George 
Published: May 2017

AbstractSolar reflective “cool pavements” have been proposed as a potential heat mitigation strategy for cities. However, previous research has not systematically investigated the extent to which cool pavements could reduce urban temperatures. In this study we investigated the climate impacts of widespread deployment of cool pavements in California cities. Using the Weather Research and Forecasting model, we simulated the current climate of California at 4 km spatial resolution. Comparing this simulation to 105 weather stations in California suggested an overall mean bias (model minus observation) of −0.30°C. Widespread pavement albedo increases of 0.1 and 0.4 in California cities were then simulated. Comparing temperature reductions for each scenario showed that the climate response to pavement albedo modification was nearly linear. Temperature reductions at 14:00 local standard time were found to be 0.32°C per 0.1 increase in grid cell average albedo. Temperature reductions were found to peak in the late morning and evening when (a) boundary layer heights were low and (b) solar irradiance (late morning) and heat accumulation in the pavement (evening) was high. Temperature reductions in summer were found to exceed those in winter, as expected. After scaling the results using realistic data‐derived urban canyon morphologies and an off‐line urban canyon albedo model, annual average surface air temperature reductions from increasing pavement albedo by 0.4 ranged from 0.18°C (Palm Springs) to 0.86°C (San Jose). The variation among cities was due to differences in baseline climate, size of the city, urban fraction, and urban morphology.
Nonparametric triple collocation
Authors: Nearing Grey S. , Yatheendradas Soni , Crow Wade T. , Bosch David D. , Cosh Michael H. , Goodrich David C. , Seyfried Mark S. , Starks Patrick J. 
Published: May 2017

AbstractTriple collocation has found widespread application in the hydrological sciences because it provides information about the errors in our measurements without requiring that we have any direct access to the true value of the variable being measured. Triple collocation derives variance‐covariance relationships between three or more independent measurement sources and an indirectly observed truth variable in the case where the measurement operators are additive. We generalize that theory to arbitrary observation operators by deriving nonparametric analogues to the total error and total correlation statistics as integrations of divergences from conditional to marginal probability ratios. The nonparametric solution to the full measurement problem is underdetermined, and we therefore retrieve conservative bounds on the theoretical total nonparametric error and correlation statistics. We examine the application of both linear and nonlinear triple collocation to synthetic examples and to a real‐data test case related to evaluating space‐borne soil moisture retrievals using sparse monitoring networks and dynamical process models.
The Formation ofACCand Competition between Polyamines and Ethylene forSAM
Authors: Harpaz‐Saad Smadar , Yoon Gyeong M. , Mattoo Autar K. , Kieber Joseph J. 
Published: May 2017

AbstractS‐adenosylmethionine (SAM) acts both as a precursor for the production of ethylene and as a substrate in the biosynthesis of polyamines. The conversion of SAM to 1‐aminocyclopropane‐1‐carboxylic acid (ACC) is a key regulatory step in the biosynthesis of ethylene and is catalyzed by the enzyme ACC synthase (ACS), which is encoded by a multi‐gene family in plants. The various ACS isoforms have diverse properties, both in terms of biochemical characteristics and regulated turnoverin vivo. Here, the characteristics of theACSgene families and the encoded proteins in various plant species, as well as the synthesis and role of polyamines and the flow of SAM into these two pathways, are discussed.
The Fate ofACCin Higher Plants
Authors: Dorling Sarah J. , McManus Michael T. 
Published: May 2017

AbstractThe fate of 1‐aminocyclopropane‐1‐carboxylate (ACC), generated by the activity of ACC synthase (ACS), is reviewed. In higher plants, ACC undergoes two known fates – the first being malonylation to form malonyl‐ACC (M‐ACC), and the role of this conjugation step as a reversible one to generate free ACC is considered. The second fate is oxidation to form ethylene and HCN. The metabolism of HCN by β‐cyanoalanine synthase (β‐CAS) is considered, including an emerging view of a role for HCN as a signalling compound in plants. For ethylene biosynthesis, the identification of the first candidate gene –pTOM13– with the demonstration of an authentic ethylene‐forming enzyme activity,in vivo, led to a very active research period concerned with the subsequent cloning of ACC oxidase (ACO) genes from a wide variety of plant species and the characterization of the biochemical properties of the enzyme. Together, these studies have contributed to the central conclusion that the ACO gene family is, in most plant species examined, comprised of (usually) 3–5 members that display differential expression in response to developmental and environmental cues. Further, there is growing evidence that ACO (and not ACS) can be the limiting step in terms of ethylene biosynthesis in certain physiological processes. Finally, the evolution of ACO is considered as the key development in the inheritance of the ACC‐dependent ethylene biosynthetic pathway in higher plants.
Ethylene in Seed Development, Dormancy and Germination
Authors: Bogatek Renata , Gniazdowska Agnieszka 
Published: May 2017

AbstractSeeds are the organs by which higher plants disperse and propagate. Seeds are relatively insensitive to stress‐inducing environmental conditions and can survive in the soil for many years in a dormant state. The alleviation of dormancy results in germination and finally seedling growth and these processes are complex and subject to hormonal control. Many plant species produce ethylene during the final phase of seed development and germination, and the application of some seed dormancy‐breaking agents, for example HCN or NO, also induces ethylene production. Therefore, it has been proposed that ethylene contributes to the alleviation of seed dormancy as well as germination. The action of ethylene during dormancy release and germination also depends on interactions with other phytohormones, and so this chapter summarizes our current knowledge on the role of ethylene as well as crosstalk between ethylene and the other phytohormones (gibberellins, abscisic acid, brassinosteroids, jasmonate and polyamines). Further, other signalling molecules such as reactive oxygen species (e.g. H2O2) or reactive nitrogen species (e.g. NO) and HCN are also discussed in terms of their roles in the regulation of seed physiology.
The Role of Ethylene in Plant Growth and Development
Authors: Vandenbussche Filip , Van Der Straeten Dominique 
Published: May 2017

AbstractEthylene has a profound effect on the shape of plants. It determines many aspects of vegetative development by interacting with other hormones. Foremost, ethylene relies on a tight collaboration with auxin to influence plant growth and can stimulate or inhibit elongation of roots and shoots. This stimulatory or inhibitory action depends on the species and on growth conditions and is controlled by modification of cell wall properties. Later in life, ethylene regulates floral transition, and in some species the gender of the flowers. In determining these architectural features, ethylene allows the plants to reach a high level of plasticity to adapt to multiple environmental challenges.
Ethylene and Senescence Processes
Authors: Graham Laura E. , Schippers Jos H.M. , Dijkwel Paul P. , Wagstaff Carol 
Published: May 2017

AbstractSenescence is a vitally important sequence of events in the latter phase of the life cycle of a plant that determines yield and reproductive success. In many species, and in different plant organs, ethylene is a key regulator of senescence and an increased understanding of the way the hormone functions will enable the timing and location of senescence to be manipulated in order to improve yield, quality and longevity. This chapter examines the physiological and molecular regulation of senescence in different plant organs and introduces the concept of the ‘senescence window’ in which plant organs are receptive to ethylene‐mediated senescence cues. Several studies have attempted to elucidate global patterns of the regulation of senescence, which have enabled the function of ethylene to be placed in the context of the involvement of other, often antagonistic, hormones in the execution of senescence and downstream processes. Finally, we examine the consequences of senescence for post‐harvest biology, an area where the control of ethylene action has been actively sought in order to control precisely the timing of senescence and ripening processes so that crop quality can be enhanced and maintained.
Phylogenetic Analyses and Morphological Innovations in Land Plants
Authors: Doyle James A. 
Published: May 2017

AbstractAn increasingly robust phylogenetic framework based on molecular and fossil data clarifies the sequence of evolutionary innovations in land plants. Oogamy and cellular novelties (phragmoplast, plasmodesmata, incipient meristems) evolved in aquatic streptophytes. Invasion of the land entailed interpolation of the sporophyte, jacketed gametangia and sporangia, and air‐dispersed spores, followed by stomata. Origin of vascular plants involved branching of the sporophyte and stepwise evolution of vascular tissue. Leaves originated independently in lycophytes and euphyllophytes; in some euphyllophytes leaves were derived from single dichotomous branches, in others from whole branch systems. In seed plants, secondary growth evolved before the seed. Pinnately compound leaves were replaced by simple leaves in coniferophytes. The origin of the angiosperm flower remains unresolved, but bitegmic ovules may be derived from cupules, and the ancestral carpel can be reconstructed as ascidiate. Evolution of double fertilization was a stepwise process that continued within angiosperms; vessels also evolved within the group. Monocots show major reorganization tied to loss of secondary growth, while pentamerous flowers evolved from dimerous within eudicots.
Comparative Evolutionary Genomics of Land Plants
Authors: Litt Amy 
Published: May 2017

AbstractThe evolution of land plants is characterized by increasing adaptation to the terrestrial environment and increasing structural complexity. Flowering plants have more elaborate structure and life cycles than do mosses, and have diversified and colonized a wider variety of habitats. Nonetheless, analyses suggest that on average flowering plants have neither larger genomes nor more genes than mosses. Genome size varies dramatically among embryophytes but the most significant factor appears to be amplification of transposable elements, which not only mediate genome size but dynamically affect genome structure and function as well. Along with whole genome duplications and lineage‐specific expansion of individual gene families, they are responsible for shaping land plant genomes, generating substantial differences in genome size, gene number, and gene order even among closely related cultivars. Comparative analyses of fully sequenced genomes have shed substantial light on the dynamics of genome and gene family evolution; they are just beginning, however, to help us understand the molecular basis of the key adaptations that have allowed plants to thrive on land.
Development and the Evolution of Plant Form
Authors: Ambrose Barbara A. , Ferrándiz Cristina 
Published: May 2017

AbstractDevelopment in land plants is the process whereby a single cell becomes a large multicellular organism. Developmental networks specify every organ, tissue, or cell type from egg to juvenile to a reproducing adult. Therefore, it would follow that changes in developmental networks result in changes in form, and understanding these developmental networks and their changes would provide great insight into the evolution of plant form. Only recently has the field of evolutionary developmental biology (evo‐devo) been recognized as an important evolutionary mechanism; however, this field is still in its nascent stages in plants. Much of the plant evo‐devo studies have focused on the flower and to some extent on the leaf. However, to understand the evolution of plant form, these ideas and studies need to be extended across the land plants. We review what we know about the contribution of development to the evolution of plant form and discuss avenues of future research.
Development in the Wild: Phenotypic Plasticity
Authors: Donohue Kathleen 
Published: May 2017

AbstractDevelopment of organisms in the wild occurs in ecologically variable environments. Phenotypic plasticity occurs when a single genotype alters its phenotype in response to its environment. Some traits are more plastic than others, and whether a particular trait evolves plasticity depends on the degree of environmental variation experienced by that trait, the quality of environment‐dependent natural selection on that trait, and the strength of genetic correlations between the trait expressed in different environments. Thus, identifying the molecular basis of pleiotropy of traits expressed in different environments should be an important agenda in studies of development and plasticity. The strength of pleiotropy across environments can be influenced by environment‐dependent gene expression and signal transduction and by the structure of genetic pathways. The degree of environmental dependence of many of these molecular processes, however, is only beginning to be elucidated. Phenotypic plasticity influences adaptation, niche breadth, and ecological ranges and has the potential to influence the evolution of reproductive isolation. Understanding the genetic and ecological mechanisms of plasticity, therefore, will enhance our knowledge of the genetic basis of adaptation and the evolution of diversity.
The Evolution of Plant Form: A Summary Perspective
Authors: Purugganan Michael 
Published: May 2017

AbstractThe study of the evolution of development (evo‐devo) has advanced dramatically in the last two decades. Although there had been a strong interest in evo‐devo for nearly a century, it was only with the advent of molecular developmental genetics that provided a strong basis for a conceptual and methodological integration of developmental studies with evolutionary biology. The study of plant evolution of development has also progressed in the last two decades beginning with the study of the molecular basis for floral diversification in the angiosperms. The confluence of studies in development, molecular genetics, phylogenetics, paleobotany, population genetics, and molecular evolution in the study of plant form is now a robust discipline, with various opportunities to further our understanding of plant morphological evolution at all levels of biological organization.
Introduction: Mysteries, Molecules and Mechanisms
Authors: Bryant John A. 
Published: May 2017

Abstract
This brief chapter mentions the main structural and functional features of plant nuclei and in doing so, provides a very general introduction to other chapters in the book. It also covers aspects that are not featured elsewhere, especially the replication of nuclear DNA and the import of the replication proteins. Throughout the chapter there is an underlying theme of evolution, relating both to the similarities to and differences from the Archaea and to the possible evolutionary origins of the nucleus.
The Nuclear Envelope – Structure and Protein Interactions
Authors: Graumann Katja , Evans David E. 
Published: May 2017

AbstractThe proteins of the nuclear envelope have been characteriszd in detail in non‐plant systems, revealing a complex series of interactions between the inner and outer nuclear envelope, with the proteins of the nuclear pore complex and connecting to the nucleoskeleton and cytoskeleton. Many of the proteins described in animal and fungal systems have not been identified in plants; however, recent advances have resulted in the description of several key plant nuclear envelope proteins including members of the Sad1/UNC84 (SUN) domain family and recently the first Klarsicht/Anc‐1/Syne‐1 Homology (KASH)‐domain protein. This chapter describes the emerging networks of protein interactions at the plant nuclear envelope, together with discussion of their likely functions. In particular, the important role of plant SUN domain proteins as a key component of a linker of nucleoskeleton and cytoskeleton complex is described together with prospects for future study of plant nuclear envelope interaction networks.
The Plant Nuclear Pore Complex – The Nucleocytoplasmic Barrier and Beyond
Authors: Zhou Xiao , Boruc Joanna , Meier Iris 
Published: May 2017

AbstractThe nuclear pore complex (NPC) provides a highly organized pathway for selective transport between the nucleoplasm and the cytoplasm. Recent work undertaken to characterize the mechanisms and regulation of transport through the plant NPC has resulted in the identification of key components showing similarities – and also significant differences – between plants and other organisms. Mutant studies reveal roles for nucleoporins in plant–microbe interactions, hormone response, abiotic‐stress tolerance, plant development, and flowering‐time regulation. Recently, significant progress has been made in identifying about 30 proteins that constitute the plant NPC as well as several NPC‐associated proteins and in characterizing the structure of the plant NPC. A newly discovered connection between nuclear pore‐associated proteins and inner nuclear envelope proteins expands our knowledge of plant nuclear envelope architecture. Dynamic patterns of subcellular localization suggest mitotic functions of plant nucleoporins away from the nuclear pore.
Genomics and Chromatin Packaging
Authors: Sanchez‐Moran Eugenio 
Published: May 2017

AbstractThe role of DNA is to store an individual's genetic information so that it can be used during development and can be copied accurately during the divisions of the cell. DNA has to be packed within a small nucleus in an organized manner to be accessible for a variety of vital cell processes (transcription, DNA replication, repair, mitosis and meiosis). This is achieved by DNA associating with different proteins to form chromatin.Different levels of compaction are involved, from the nucleosome fibre to higher order chromatin structures. All the chromatin components involved at different levels of DNA compaction are highly dynamic, allowing the required accessibility.The understanding of chromatin components, their dynamics and interactions in plants would allow us to provide plant breeders with new tools to help fulfil the increased demand for food that will be required in future decades of increased global population and climate change.