bluuebunny/crossref_metadata_2025_split huggingface dataset:
The magmatic plumbing system of the Askja central volcano, Iceland, as imaged by seismic tomography
Authors: Greenfield Tim , White Robert S. , Roecker Steven 
Published: September 2016

AbstractThe magmatic plumbing system beneath Askja, a volcano in the central Icelandic highlands, is imaged using local earthquake tomography. We use a catalog of more than 1300 earthquakes widely distributed in location and depth to invert for the P wave velocity (Vp) and the Vp/Vs ratio. Extensive synthetic tests show that the minimum size of any velocity anomaly recovered by the model is ~4 km in the upper crust (depth < 8 km below sea level (bsl)), increasing to ~10 km in the lower crust at a depth of 20 km bsl. The plumbing system of Askja is revealed as a series of high‐Vp/Vs ratio bodies situated at discrete depths throughout the crust to depths of over 20 km. We interpret these to be regions of the crust which currently store melt with melt fractions of ~10%. The lower crustal bodies are all seismically active, suggesting that melt is being actively transported in these regions. The main melt storage regions lie beneath Askja volcano, concentrated at depths of 5 km bsl with a smaller region at 9 km bsl. Their total volume is ~100 km3. Using the recorded waveforms, we show that there is also likely to be a small, highly attenuating magmatic body at a shallower depth of about 2 km bsl.
Surface shear stress dependence of gas transfer velocity parameterizations using DNS
Authors: Fredriksson S. T. , Arneborg L. , Nilsson H. , Handler R. A. 
Published: September 2016

AbstractAir‐water gas‐exchange is studied in direct numerical simulations (DNS) of free‐surface flows driven by natural convection and weak winds. The wind is modeled as a constant surface‐shear‐stress and the gas‐transfer is modeled via a passive scalar. The simulations are characterized via a Richardson number
where
,
, and
are the buoyancy flux, kinematic viscosity, and friction velocity respectively. The simulations comprise
ranging from convection‐dominated to shear‐dominated cases. The results are used to: (i) evaluate parameterizations of the air‐water gas‐exchange, (ii) determine, for a given buoyancy flux, the wind speed at which gas transfer becomes primarily shear driven, and (iii) find an expression for the gas‐transfer velocity for flows driven by both convection and shear. The evaluated gas transfer‐velocity parametrizations are based on either the rate of turbulent kinetic energy dissipation, the surface flow‐divergence, the surface heat‐flux, or the wind‐speed. The parametrizations based on dissipation or divergence show an unfavorable
dependence for flows with combined forcing whereas the parametrization based on heat‐flux only shows a limited
dependence. The two parametrizations based on wind speed give reasonable estimates for the transfer‐velocity, depending however on the surface heat‐flux. The transition from convection‐ to shear‐dominated gas‐transfer‐velocity is shown to be at
. Furthermore, the gas‐transfer is shown to be well represented by two different approaches: (i) additive forcing expressed as
where
, and (ii) either buoyancy or shear dominated expressed as,
or
. Here
and
are constants, and
is an exponent that depends on the water surface‐characteristics.
Uncertainties in radiometer intercalibration associated with variability in geophysical parameters
Authors: Yang John Xun , McKague Darren S. , Ruf Christopher S. 
Published: September 2016

AbstractSpaceborne radiometry plays a major role in weather and climate science and applications. Intercalibrating different radiometers has become an indispensable task for diagnosing instrument performance and integrating constellation data to extend the observational record. Because intercalibration affects both base radiance data and downstream science products, it is critical to examine intercalibration performance. In this study, we use constellation radiometer data from the Global Precipitation Measurement mission to detect and characterize a pronounced variability in intercalibration stability with a ~40 day periodicity. A regional dependence of the calibration is also found. The variability is related to geophysical parameters including water vapor, surface wind speed, and sea surface temperature. It is found that the variability is caused by periodic variations in the local times and locations of the overlap regions between spacecraft. An analytical orbit model is developed for calculating the period of oscillation and agrees well with observation. Calibration errors show nonlinear and nonmonotonic dependences on geophysical parameters and brightness temperature, which cannot be removed by simple linear regression. The variability affects both base radiance calibration accuracy and retrieved science data products.
Temperature and precipitation extremes in century‐long gridded observations, reanalyses, and atmospheric model simulations
Authors: Donat Markus G. , Alexander Lisa V. , Herold Nicholas , Dittus Andrea J. 
Published: September 2016

AbstractKnowledge about long‐term changes in climate extremes is vital to better understand multidecadal climate variability and long‐term changes and to place today's extreme events in a historical context. While global changes in temperature and precipitation extremes since the midtwentieth century are well studied, knowledge about century‐scale changes is limited. This paper analyses a range of largely independent observations‐based data sets covering 1901–2010 for long‐term changes and interannual variability in daily scale temperature and precipitation extremes. We compare across data sets for consistency to ascertain our confidence in century‐scale changes in extremes. We find consistent warming trends in temperature extremes globally and in most land areas over the past century. For precipitation extremes we find global tendencies toward more intense rainfall throughout much of the twentieth century; however, local changes are spatially more variable. While global time series of the different data sets agree well after about 1950, they often show different changes during the first half of the twentieth century. In regions with good observational coverage, gridded observations and reanalyses agree well throughout the entire past century. Simulations with an atmospheric model suggest that ocean temperatures and sea ice may explain up to about 50% of interannual variability in the global average of temperature extremes, and about 15% in the global average of moderate precipitation extremes, but local correlations are mostly significant only in low latitudes.
Contrasting cloud composition between coupled and decoupled marine boundary layer clouds
Authors: Wang Zhen , Mora Ramirez Marco , Dadashazar Hossein , MacDonald Alex B. , Crosbie Ewan , Bates Kelvin H. , Coggon Matthew M. , Craven Jill S. , Lynch Peng , Campbell James R. , Azadi Aghdam Mojtaba , Woods Roy K. , Jonsson Haflidi , Flagan Richard C. , Seinfeld John H. , Sorooshian Armin 
Published: September 2016

AbstractMarine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds for dissolved nonwater substances. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July–August of separate years (Eastern Pacific Emitted Aerosol Cloud Experiment 2011, Nucleation in California Experiment 2013, and Biological and Oceanic Atmospheric Study 2015). Decoupled clouds exhibited significantly lower air‐equivalent mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and subcloud aerosol (Dp > 100 nm) number concentration, owing to detachment from surface sources. Nonrefractory submicrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long‐range transport from more distant sources. Sodium and chloride dominated in terms of air‐equivalent concentration in cloud water for coupled clouds, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea‐salt constituents (e.g., Cl, Na, Mg, and K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. Satellite and Navy Aerosol Analysis and Prediction System‐based reanalysis data are compared with each other, and the airborne data to conclude that limitations in resolving boundary layer processes in a global model prevent it from accurately quantifying observed differences between coupled and decoupled cloud composition.
Timing and conditions of clay fault gouge formation on the Naxos detachment (Cyclades, Greece)
Authors: Mancktelow N. , Zwingmann H. , Mulch A. 
Published: September 2016

AbstractClay fault gouge from the Naxos detachment (locally up to 1.0–1.5 m thick) is reported and dated for the first time. K‐Ar ages on eight clay size fractions from the detachment and a minor fault in the immediate footwall have a narrow range, from 10.3 to 9.0 Ma, with an average of 9.7 ± 0.5 Ma (±1σ). These results are in excellent accord with regional and local age constraints, independently demonstrating the reliability of the method. Hydrogen δD values fall in the range −89 to −95‰, indicating interaction with infiltrating meteoric water during gouge formation, which is consistent with deposition of freshwater sediments in the hanging wall at the same time. Clay mineralogy in the detachment gouge is predominantly mixed layer illite‐smectite with subordinate 1 M illite and kaolinite but without higher‐temperature 2 M1 illite/mica. Clay fault gouge predominantly formed over a limited time and temperature range, potentially acting as a weak lubricant promoting movement on the Naxos detachment, with correspondingly rapid exhumation and cooling of the underlying footwall.
Lithospheric strength variations in Mainland China: Tectonic implications
Authors: Deng Yangfan , Tesauro Magdala 
Published: September 2016

AbstractWe present a new thermal and strength model for the lithosphere of Mainland China. To this purpose, we integrate a thermal model for the crust, using a 3‐D steady state heat conduction equation, with estimates for the upper mantle thermal structure, obtained by inverting a S wave tomography model. With this new thermal model and assigning to the lithospheric layers a “soft” and “hard” rheology, respectively, we estimate integrated strength of the lithosphere. In the Ordos and the Sichuan basins, characterized by intermediate temperatures, strength is primarily concentrated in the crust, when the rheology is soft, and in both the crust and upper mantle, when the rheology is hard. In turn, the Tibetan Plateau and the Tarim basin have a weak and strong lithosphere mainly on account of their high and low temperatures, respectively. A comparison of temperatures, strength, and effective viscosity variations with earthquakes distribution and their seismic energy released indicates that both the deep part of the crust and the upper mantle of the Tibetan Plateau are weak and prone to flow toward adjacent areas. The high strength of some of the tectonic domains surrounding Tibet (Tarim, Ordos, and Sichuan basins) favors the flow toward the weak western part of South China block.
Predator Avoidance
Authors: Abrahams Mark V , Piersiak Michael G 
Published: September 2016

AbstractFor prey species to be successful, they must balance the conflicting demands of obtaining the resources necessary for survival while avoiding being killed by predators. This has a hierarchy of approaches that begins with avoiding dangerous (=predators) times and locations, using dangerous locations but adopting behaviours and tactics that assist prey in detecting predators first. If a predator detects them, they may also plan for this by staying in groups, thereby diluting the chance of being the individual that is killed or using coordinated group defence. Individuals may also employ toxins or specialised morphologies that deter a predator from attacking or assist in escape. Assuming that individual behaviour is not affected by the presence of parasites, prey may also escape predators after capture using specialised morphologies, and even ejecting limbs. Ultimately, captured prey may even try to attract other predators with the hope of escaping during the ensuing melee.Key ConceptsBehavioural trade‐offs.The role of predators in affecting habitat quality.Costs and benefits of group living.The role of antipredator morphology.Batesian and Mullerian mimicry.The impact of parasites and how they can modify behaviour.Animal scaling, physics and its impact upon behaviour.The ecological importance of predators.Conservation ecology.
Simple Repeats
Authors: Schlötterer Christian 
Published: September 2016

Abstract

The eukaryotic genome deviates in many aspects from a random base composition. One interesting deviation is that some parts of the genome are less complex than expected, leading to an overrepresentation of short sequence motifs. Owing to their low complexity, these genomic regions are called simple sequences. The most extreme case is the tandem repetition of a single motif. Once the motif is repeated multiple times (at least ≈ 10x), this sequence is called a microsatellite. Like the rest of the genome, simple sequences acquire base substitutions, but on top of this they have a proprietary mutation process – deoxyribonucleic acid replication slippage. With increasing simplicity, this mutation process becomes increasingly important, resulting in the gain and loss of repeat units. Their high mutation rate provides the basis for the successful use of microsatellites as genetic markers.

Key Concepts

Some parts of the genome have low complexity

These simple sequences have a proprietary mutation process called DNA replication slippage.

DNA replication slippage adds/removes repeat units.

Microsatellites are an informative genetic marker.

Simple sequences are distributed throughout the entire genome, making them an excellent tool for gene mapping.
History of Scientific Agriculture: Animals
Authors: Thompson R Paul 
Published: September 2016

Abstract

Domestication of agricultural animals began 10 000 years ago. From a wide array of wild animals, only a small number were and, for specifiable reasons, could be domesticated. Trait selection and breeding has been the principal mechanism of animal improvement until the late twentieth century. As with much of early science, enhancing beneficial traits was a trial and error process. An understanding of the genetic mechanisms and environmental factors in that process was a twentieth‐century triumph. Drawing on physiological, behavioural, genetic, evolutionary and ecological knowledge significantly enhanced selection and breeding efforts. In the twentieth century, scientific advancements were numerous. Of special significance were the introduction of artificial insemination, and the nature, prevention and treatment of pathogenic diseases. Late twentieth‐century agricultural biology began to employ techniques of molecular genetic manipulation (transgenic animals), initially using farm animals as bioreactors. Improvements in cloning, pronuclear injection and use of stem cells can be expected to dominate research and development in twenty‐first‐century animal agriculture.

Key Concepts

The early evolution of animal domestication was trial and error.

Human and agricultural animals coevolved.

The mechanisms of speciation were important processes in the early period but only well understood in the twentieth century.

The quantitative genetics of farm animal makes trait improvement challenging.

Critical variables in the trait farm animals are understood but difficult to manipulate.

The importance of multiple trait selection is now well understood.

Artificial insemination and cryopreservation of sperm have significantly improved trait manipulation and preservation.

Knowledge of pathogens has allowed antibiotics and sanitation to be effectively employed.

Animals as pharmaceutical and material bioreactors has been recent and expanded the genetic modification of animals.

There are challenges and promises of cloning, pronuclear injection and stem cell use in animal agriculture emerging in the twenty‐first century.
Positional Information
Authors: Wolpert Lewis 
Published: September 2016

Abstract

The concept of positional information proposes that cells acquire positional values as in a coordinate system, which they interpret by developing in particular ways to give rise to spatial patterns. Some of the best evidence for positional information comes from regeneration experiments, and the patterning of the vertebrate limb. Central problems are how positional information is set up, how it is recorded and then how it is interpreted by the cells. A number of models have been proposed for the setting up of positional gradients, and most are based on diffusion of a morphogen and its interactions with extracellular molecules; however, diffusion may not be reliable mechanism. There are also mechanisms based on timing. There is no good evidence for the quantitative aspects of any of the proposed gradients and details of how they are set up.

Key Concepts

Pattern is the spatial organisation of the embryo.

Positional information proposes that cells acquire positional values as in a coordinate system, which they interpret by developing in particular ways to give rise to spatial patterns.

Morphogens are chemical gradients that might provide positional Information.

Position can be specified by a timing mechanism.

Turing spatial models are based on reaction diffusion and can generate repeated forms.
X
‐Ray Emission Spectroscopic Techniques in Bioinorganic Applications
Authors: DeBeer Serena , Bergmann Uwe 
Published: September 2016

Abstract
Hard X‐ray core hole spectroscopy plays an important role in countless areas of research including chemistry, physics, biology, materials science, medicine, geoscience, and even natural and cultural heritage. The main attraction of these methods lies in the atomic level structural and chemical information, the elemental selectivity, and the practical advantages related to the penetration power of hard X‐rays, allowing for a wide range of samples and sample environments. Powerful synchrotron sources with intense, tunable, and highly collimated X‐ray beams have pushed the detection limit for X‐ray spectroscopy to minute elemental concentrations, including the active sites in dilute metalloproteins. Much of the focus over the past 40 years has been on X‐ray absorption spectroscopy (XAS) methods including X‐ray absorption near edge structure (XANES) and extended range X‐ray absorption fine structure (EXAFS) spectroscopy. More recently, there has been an increasing activity in X‐ray emission spectroscopy (XES) and other high‐resolution photon‐out techniques such as X‐ray Raman scattering. These efforts have been aided by the development of efficient, dedicated, high‐resolution photon‐out X‐ray spectrometers that are now routinely used at many synchrotron facilities. XES provides information on the local atomic and electronic structure that is complementary to X‐ray scattering and diffraction methods and XAS. We will discuss various XES techniques and their specific benefits and limitations regarding studies in bioinorganic chemistry and describe examples of recent results. We will present the basic information regarding the required instrumentation, discuss the various approaches, and give a comprehensive instrumentation literature review.
With the advent of X‐ray free electron lasers (XFELs), fourth‐generation synchrotron light sources that are many orders of magnitude brighter than storage rings, revolutionary new capabilities for the studies of many materials on times scales down to femtoseconds have become available. Owing to the stochastic nature of the XFEL pulses, XES techniques, where the whole spectrum is collected in a shot‐by‐shot manner, are specifically attractive and have been the predominant choice of the early XFEL‐based X‐ray spectroscopy work. We will discuss this work and the related instrumentation from the perspective of the bioinorganic field. We conclude with a few thoughts on potential future XES techniques, which take advantage of nonlinear processes that result from the interaction of very intense XFEL pulses with matter.
Photocatalytic Production of Hydrogen with Earth‐Abundant Metal Catalysts
Authors: Fukuzumi Shunichi , Yamada Yusuke 
Published: September 2016

Abstract

Photocatalytic production of hydrogen occurs by combination of model compounds of the photosynthetic reaction center with organic photocatalysts and earth‐abundant metal nanoparticles as proton reduction catalysts and with visible light irradiation of an acetonitrile–water mixture solvent containing a sacrificial electron donor. Mesoporous silica–alumina was utilized to incorporate organic photocatalysts and earth‐abundant metal nanoparticles together as composite catalysts in an aqueous solution. Earth‐abundant metal nanoparticles were produced
in situ
by the photoreduction of metal salts with oxalate anion in mesoporous silica–alumina. The photocatalytic hydrogen evolution with nicotinamide adenine dinucleotide (NADH) was enhanced by a synergistic effect of Ni and Cu supported on TiO
2
and SiO
2
. Such a synergistic effect among base metals and metal oxides provides a promising strategy to develop active catalysts for hydrogen evolution without using platinum group metals.