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"Knight, J"
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Iconographic method in new world prehistory
\"This book offers an overview of iconographic methods and their application to archaeological analysis\"-- Provided by publisher.
Book
Soil organic nitrogen
Background
For more than a century, crop N nutrition research has primarily focused on inorganic N (IN) dynamics, building the traditional model that agricultural plants predominantly take up N in the form of NO
3
−
and NH
4
+
. However, results reported in the ecological and agricultural literature suggest that the traditional model of plant N nutrition is oversimplified.
Scope
We examine the role of organic N (ON) in plant N nutrition, first by reviewing the historical discoveries by ecologists of plant ON uptake, then by discussing the advancements of key analytical techniques that have furthered the cause (stable isotope and microdialysis techniques). The current state of knowledge on soil ON dynamics is analyzed concurrently with recent developments that show ON uptake and assimilation by agricultural plant species. Lastly, we consider the relationship between ON uptake and nitrogen use efficiency (NUE) in an agricultural context.
Conclusions
We propose several mechanisms by which ON uptake and assimilation may increase crop NUE, such as by reducing N assimilation costs, promoting root biomass growth, shaping N cycling microbial communities, recapturing exuded N compounds, and aligning the root uptake capacity to the soil N supply in highly fertilized systems. These hypothetical mechanisms should direct future research on the topic. Although the quantitative role remains unknown, ON compounds should be considered as significant contributors to plant N nutrition.
Journal Article
Robust but weak winter atmospheric circulation response to future Arctic sea ice loss
The possibility that Arctic sea ice loss weakens mid-latitude westerlies, promoting more severe cold winters, has sparked more than a decade of scientific debate, with apparent support from observations but inconclusive modelling evidence. Here we show that sixteen models contributing to the Polar Amplification Model Intercomparison Project simulate a weakening of mid-latitude westerlies in response to projected Arctic sea ice loss. We develop an emergent constraint based on eddy feedback, which is 1.2 to 3 times too weak in the models, suggesting that the real-world weakening lies towards the higher end of the model simulations. Still, the modelled response to Arctic sea ice loss is weak: the North Atlantic Oscillation response is similar in magnitude and offsets the projected response to increased greenhouse gases, but would only account for around 10% of variations in individual years. We further find that relationships between Arctic sea ice and atmospheric circulation have weakened recently in observations and are no longer inconsistent with those in models.
The degree to which Arctic sea ice decline influences the mid-latitude atmospheric circulation is widely debated. Here, the authors use a coordinated multi-model experiment to show that Arctic sea ice loss causes a weakening of the mid-latitude westerly winds, but the effect is overall small.
Journal Article
The Bloomsbury companion to phonetics
The 'Bloomsbury Companion To Phonetics' is designed to be the essential one-volume resource for advanced students and academics. It offers a comprehensive reference resource, giving an overview of key topics and key terms in phonetics. It offers a survey of current research areas and new directions in the field as well as featuring a manageable guide to beginning or developing research.
Book
Landsat-8 Operational Land Imager Design, Characterization and Performance
The Operational Land Imager (OLI) on Landsat-8 represents a generational change from heritage Landsat instruments in its design, while it maintains data continuity with the 40+ year Landsat data archive. It preserves the 30-m ground sample distance, 185-km swath width and VIS/NIR/SWIR spectral bands. Furthermore, data continuity resulted from extensive pre-launch and on-orbit calibration and characterization campaigns. This paper presents an overview of the OLI design, the pre-launch characterization results and the on-orbit performance.
Journal Article
Functions and mechanics of dynein motor proteins
Key Points
Cell biological studies have identified roles for dynein motors in many
in vivo
processes. These include transporting diverse intracellular cargo along microtubules, organizing microtubules within the cell division machinery and powering the beating of cilia and flagella.
Unlike myosin and kinesin, which share an ancestry with G proteins, dynein evolved from the AAA+ superfamily of ring-shaped ATPases.
In outline, the mechanochemical cycle of dynein is similar to that of myosin, but the underlying mechanism of its movement is quite different.
Recent structural studies point towards a model in which nucleotide-driven flexing motions in the dynein AAA+ ring are coupled to the remodelling of a mechanical element called the linker domain.
The ATPase and microtubule-binding domains of dynein are spatially separated by a coiled-coil stalk, which is thought to mediate allosteric communication via small sliding movements between its constituent α-helices.
Single-molecule studies are starting to reveal how the paired motor domains in cytoplasmic dynein dimers move along microtubules, but the extent to which the motor domains communicate with each other and how much force they produce are controversial.
Fuelled by ATP hydrolysis, dyneins generate force and movement on microtubules in a wealth of biological processes. A model for the mechanochemical cycle of dynein is emerging, in which nucleotide-driven flexing motions within the AAA+ ring of dynein alter the affinity of its microtubule-binding 'stalk' and reshape its mechanical element to generate movement.
Fuelled by ATP hydrolysis, dyneins generate force and movement on microtubules in a wealth of biological processes, including ciliary beating, cell division and intracellular transport. The large mass and complexity of dynein motors have made elucidating their mechanisms a sizable task. Yet, through a combination of approaches, including X-ray crystallography, cryo-electron microscopy, single-molecule assays and biochemical experiments, important progress has been made towards understanding how these giant motor proteins work. From these studies, a model for the mechanochemical cycle of dynein is emerging, in which nucleotide-driven flexing motions within the AAA+ ring of dynein alter the affinity of its microtubule-binding stalk and reshape its mechanical element to generate movement.
Journal Article
Why Peer Discussion Improves Student Performance on In-Class Concept Questions
When students answer an in-class conceptual question individually using clickers, discuss it with their neighbors, and then revote on the same question, the percentage of correct answers typically increases. This outcome could result from gains in understanding during discussion, or simply from peer influence of knowledgeable students on their neighbors. To distinguish between these alternatives in an undergraduate genetics course, we followed the above exercise with a second, similar (isomorphic) question on the same concept that students answered individually. Our results indicate that peer discussion enhances understanding, even when none of the students in a discussion group originally knows the correct answer.
Journal Article