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Plate tectonics : continental drift and mountain building
This volume presents an introduction to the field of plate tectonics. Plate tectonics is a scientific theory which describes the large scale motions of Earth's rigid outermost shell. The authors begin with an historical introduction concerning early ideas of continental drift and Earth dynamics that leads into discussion and consideration of plate motions and geometry. This is followed by several chapters that define, describe in detail, and illustrate the various features, processes, and settings that comprise the plate tectonic realm: graben structures, passive continental margins, ocean basins, mid-ocean ridges, subduction zones, and transform faults. The remaining chapters deal with mountain-building processes as a consequence of plate tectonics and the collision of terranes and large continents. These chapters illuminate plate tectonic processes from the early history of the Earth to the present.-- Source other than Library of Congress.
Book
Antibody evasion by SARS-CoV-2 Omicron subvariants BA.2.12.1, BA.4 and BA.5
SARS-CoV-2 Omicron subvariants BA.2.12.1 and BA.4/5 have surged notably to become dominant in the United States and South Africa, respectively
. These new subvariants carrying further mutations in their spike proteins raise concerns that they may further evade neutralizing antibodies, thereby further compromising the efficacy of COVID-19 vaccines and therapeutic monoclonals. We now report findings from a systematic antigenic analysis of these surging Omicron subvariants. BA.2.12.1 is only modestly (1.8-fold) more resistant to sera from vaccinated and boosted individuals than BA.2. However, BA.4/5 is substantially (4.2-fold) more resistant and thus more likely to lead to vaccine breakthrough infections. Mutation at spike residue L452 found in both BA.2.12.1 and BA.4/5 facilitates escape from some antibodies directed to the so-called class 2 and 3 regions of the receptor-binding domain
. The F486V mutation found in BA.4/5 facilitates escape from certain class 1 and 2 antibodies but compromises the spike affinity for the viral receptor. The R493Q reversion mutation, however, restores receptor affinity and consequently the fitness of BA.4/5. Among therapeutic antibodies authorized for clinical use, only bebtelovimab retains full potency against both BA.2.12.1 and BA.4/5. The Omicron lineage of SARS-CoV-2 continues to evolve, successively yielding subvariants that are not only more transmissible but also more evasive to antibodies.
Journal Article
Emergence of Drift Variants That May Affect COVID-19 Vaccine Development and Antibody Treatment
New coronavirus (SARS-CoV-2) treatments and vaccines are under development to combat COVID-19. Several approaches are being used by scientists for investigation, including (1) various small molecule approaches targeting RNA polymerase, 3C-like protease, and RNA endonuclease; and (2) exploration of antibodies obtained from convalescent plasma from patients who have recovered from COVID-19. The coronavirus genome is highly prone to mutations that lead to genetic drift and escape from immune recognition; thus, it is imperative that sub-strains with different mutations are also accounted for during vaccine development. As the disease has grown to become a pandemic, B-cell and T-cell epitopes predicted from SARS coronavirus have been reported. Using the epitope information along with variants of the virus, we have found several variants which might cause drifts. Among such variants, 23403A>G variant (p.D614G) in spike protein B-cell epitope is observed frequently in European countries, such as the Netherlands, Switzerland, and France, but seldom observed in China.
Journal Article
Broadly neutralizing antibodies overcome SARS-CoV-2 Omicron antigenic shift
The recently emerged SARS-CoV-2 Omicron variant encodes 37 amino acid substitutions in the spike protein, 15 of which are in the receptor-binding domain (RBD), thereby raising concerns about the effectiveness of available vaccines and antibody-based therapeutics. Here we show that the Omicron RBD binds to human ACE2 with enhanced affinity, relative to the Wuhan-Hu-1 RBD, and binds to mouse ACE2. Marked reductions in neutralizing activity were observed against Omicron compared to the ancestral pseudovirus in plasma from convalescent individuals and from individuals who had been vaccinated against SARS-CoV-2, but this loss was less pronounced after a third dose of vaccine. Most monoclonal antibodies that are directed against the receptor-binding motif lost in vitro neutralizing activity against Omicron, with only 3 out of 29 monoclonal antibodies retaining unaltered potency, including the ACE2-mimicking S2K146 antibody
. Furthermore, a fraction of broadly neutralizing sarbecovirus monoclonal antibodies neutralized Omicron through recognition of antigenic sites outside the receptor-binding motif, including sotrovimab
, S2X259
and S2H97
. The magnitude of Omicron-mediated immune evasion marks a major antigenic shift in SARS-CoV-2. Broadly neutralizing monoclonal antibodies that recognize RBD epitopes that are conserved among SARS-CoV-2 variants and other sarbecoviruses may prove key to controlling the ongoing pandemic and future zoonotic spillovers.
Journal Article
Concept learning using one-class classifiers for implicit drift detection in evolving data streams
Data stream mining has become an important research area over the past decade due to the increasing amount of data available today. Sources from various domains generate a near-limitless volume of data in temporal order. Such data are referred to as data streams, and are generally nonstationary as the characteristics of data evolves over time. This phenomenon is called concept drift, and is an issue of great importance in the literature, since it makes models obsolete by decreasing their predictive performance. In the presence of concept drift, it is necessary to adapt to change in data to build more robust and effective classifiers. Drift detectors are designed to run jointly with classification models, updating them when a significant change in data distribution is observed. In this paper, we present an implicit (unsupervised) algorithm called One-Class Drift Detector (OCDD), which uses a one-class learner with a sliding window to detect concept drift. We perform a comprehensive evaluation on mostly recent 17 prevalent concept drift detection methods and an adaptive classifier using 13 datasets. The results show that OCDD outperforms the other methods by producing models with better predictive performance on both real-world and synthetic datasets.
Journal Article
Rorke's Drift and Isandlwana
The battle of Isandlwana on 22 January 1879, the first major encounter in the Anglo-Zulu War, witnessed the worst single day's loss of British troops between the battle of Waterloo in 1815 and the opening campaigns of the First World War in August 1914. Moreover, decisive defeat at the hands of the Zulu came as an immense shock to a Victorian public that had become used to easy victories over less technologically advanced indigenous foes in an expanding empire. 0The successful defence of Rorke's Drift, which immediately followed the encounter at Isandlwana (and for which 11 Victoria Crosses were awarded), averted military disaster and went some way to restore wounded British pride, but the sobering memory of defeat at Isandlwana lingered for many years, while the legendary tale of the defence of Rorke's Drift was re-awakened for a new generation in the epic 1964 film Zulu, starring Michael Caine. 0In this new volume in the Great Battles series, Ian F. W. Beckett tells the story of both battles, investigating not only their immediate military significance but also providing the first overarching account of their continuing cultural impact and legacy in the years since 1879, not just in Britain but also from the once largely inaccessible and overlooked Zulu perspective.
Book
Seasonal changes in invertebrate drift: effects of declining summer flows on prey abundance for drift-feeding fishes
To evaluate the consequences of declining summer discharge for drift abundance and energy flux to drift-feeding fish, we collected monthly drift samples from April to September in three small British Columbia salmonid streams. We complemented this with an analysis of published studies to test for broader-scale effects of summer low flows across multiple streams. This analysis indicated that a reduction in drift biomass concentration (mg m
−3
) over the summer low-flow recession appears to be typical in most temperate and Mediterranean climate streams. However, there was also some evidence for a behavioral increase in drift at flows below 5% of mean annual discharge (MAD), although this threshold should be treated as provisional because of low sample size. A general decline in drift biomass per m
3
over the summer low-flow recession suggests that energy flow and therefore habitat capacity for drift-feeding salmonids likely decreases much more quickly than discharge, or with predictions from traditional instream flow models that only consider flow-related changes in available physical habitat and neglect changes in prey abundance.
Journal Article