Life histories and population dynamics of early successional corals

The sequence and prog~ession of early colonization by Jamaican reef corals was followed for up to six years. Replicate m areas at depths of 10m to 20m were initially cleared and monitored pbotographicallyat annual intervals. Both sexual (larval) and asexual (vegetative) recruituent occurred. Rates of larval r~cruitment into adjacent control areas was almost 4 tim~s lower, indicating that coral settleuent and/or early survival is strongly density-dependent. Asexual recruitment was independent of coral cover. Almost 90% of larval recruitment was by LePtoseris cucullata and Agaricia agaricites, which wer~ characterized by rapid growth rates, fragile foliaceous skeletons, small colony size, and high mortality. Asexual propagules of corals were virtually absent at 20m, but ramose fragments of Madracis mirabilis, Porites porites, and Acropora cervicornis accounted for one-third of the total recruitement at 10m. These species had low rates of larval recruituent, fast growth rates, and formed large branching clones. Although asexual recruits were larger than newly settled larvae, their survivorship was generally DlJch lower. Recruitment and mortality rates varied significantly from year to year. Larval input varied four-fold, while asexual recruitment fluctuated over a 12-fold range. furtality, especially of small corals, rose sharply in 1983/84 following an algal bloom caused by the mass mortality of the grazing echinoid Diadema antillarum. The number of colonies of ~ agaricites and ~ cucullata in cleared quadrats reached and then exceeded control levels after only 4 years, although after 6 years few colonies had gro~ to the size of the largest colonies found nearby. Populations of these two species had almost fully recovered in the experiuentally disturbed sites, while other locally abundant species were virtually absent

Genetic differentiation, reproductive mode, and gene flow in the brooding coral Pocillopora damicornis along the Great Barrier Reef, Australia

The widespread and morphologically variable coral Pocillopora damicornis has been reported to exhibit huge variation in life-history traits (e.g. mode of reproduction, growth rate, longevity and dispersal) both locally and regionally throughout the Indo-Pacific Ocean. Dispersal may be achieved by the settlement of sexually or asexually generated brooded planula larvae, by broadcast spawning or more locally through asexual fragmentation of large colonies. In the present study, we conducted a hierarchical survey of allozyme variation within and among reef-crest sites on 3 mid-shelf reefs separated by up to 1200 km on the Great Barrier Reef (GBR), Australia. Our objective was to use allozyme data (1) to quantify local and regional patterns of variation in P. damicornis (along the northeastern coast of Australia), (2) to determine the relative contribution of sexual versus asexual production of planulae in P. damicornis, and (3) to estimate levels of gene flow among adjacent sites (>5 km apart) and among reefs separated by 500 to 1200 km. High levels of genotypic diversity in our samples of P. damicornis imply that dispersive propagules in this species are produced sexually rather than asexually along the length of the GBR. Corals at all sites displayed the same level of multi-locus genotypic diversity expected for randomly mating, sexually derived populations, and the majority of individual colonies possessed unique 7-locus genotypes. We also detected consistent deficits of heterozygotes within each collection (from 3 local sites on each of the 3 widely spaced reefs). This pattern is consistent with the predicted effects of sexual reproduction associated with some localised dispersal of gametes or larvae (although other explanations cannot be excluded). Furthermore, each reef was genetically subdivided, suggesting that larval recruitment was localised and that these populations are slightly inbred: hierarchical analysis of the standardised genetic variances (FST)(estimated as Weir & Cockerham's Θ) revealed that, although there was only moderate variation among all 9 sites (FST = 0.055 ± 0.029), more variation was found among sites within reefs (FSL= 0.035 ± 0.04 to 0.088 ± 0.033) than among distant reefs (FLT= 0.008 ± 0.014). This homogeneity of gene frequencies across widely separated reefs implies that reefs are connected by high levels of gene flow (Nem = ca 31) and that local populations of P. damicornis separated by >1000 km can interbreed sufficiently to maintain a consistent suite of life-history characters

Increasing thermal stress for tropical coral reefs: 1871-2017

Tropical corals live close to their upper thermal limit making them vulnerable to unusually warm summer sea temperatures. The resulting thermal stress can lead to breakdown of the coral-algal symbiosis, essential for the functioning of reefs, and cause coral bleaching. Mass coral bleaching is a modern phenomenon associated with increases in reef temperatures due to recent global warming. Widespread bleaching has typically occurred during El Nino events. We examine the historical level of stress for 100 coral reef locations with robust bleaching histories. The level of thermal stress (based on a degree heating month index, DHMI) at these locations during the 2015-2016 El Nino was unprecedented over the period 1871-2017 and exceeded that of the strong 1997-1998 El Nino. The DHMI was also 5 times the level of thermal stress associated with the 'pre-industrial', 1877-1878, El Nino. Coral reefs have, therefore, already shown their vulnerability to the modest (similar to 0.92 degrees C) global warming that has occurred to date. Estimates of future levels of thermal stress suggest that even the optimistic 1.5 degrees C Paris Agreement target is insufficient to prevent more frequent mass bleaching events for the world's reefs. Effectively, reefs of the future will not be the same as those of the past

Moving on up: Second-Line Agents as Initial Treatment for Newly-Diagnosed Patients with Chronic Phase CML

The treatment of chronic myelogenous leukemia (CML) was revolutionized by the development of imatinib mesylate, a small molecule inhibitor of several protein tyrosine kinases, including the ABL1 protein tyrosine kinase. The current second generation of FDA-approved ABL tyrosine kinase inhibitors, dasatinib and nilotinib, are more potent inhibitors of BCR-ABL1 kinase in vitro. Originally approved for the treatment of patients who were refractory to or intolerant of imatinib, dasatinib and nilotinib are now also FDA approved in the first-line setting. The choice of tyrosine kinase inhibitor (ie, standard or high dose imatinib, dasatinib, nilotinib) to use for initial therapy in chronic-phase CML (CML-CP) will not always be obvious. Therapy selection will depend on both clinical and molecular factors, which we will discuss in this review

Chapter 04: Ecological resilience, climate change and the Great Barrier Reef

The vulnerability assessments in this volume frequently refer to the resilience of various ecosystem elements in the face of climate change. This chapter provides an introduction to the concept of ecological resilience, and its application as part of a management response to climate change threats. As defined in the glossary, resilience refers to the capacity of a system to absorb shocks, resist dramatic changes in condition, and maintain or recover key functions and processes, without undergoing “phase shifts” to a qualitatively different state. For example, people who are physically and mentally fit and strong will have good prospect of recovery from disease, injury or trauma: they are resilient.This is Chapter 4 of Climate change and the Great Barrier Reef: a vulnerability assessment. The entire book can be found at http://hdl.handle.net/11017/13

Diode and final-focus simulations for DARHT

Beam dynamics calculations for the injector and final-focus region of a 4 kA, 20 MeV linear induction accelerator are presented. The injector is a low-emittance 4 MeV thermionic or photocathode diode designed to produce four 70 ns pulses over 2 {micro}sec. Due to the long total pule length, the authors have kept the field stress to < 200 kV/cm over the cathode electrode, and to {approx} 50 kV/cm on the radial insulator stacks. The normalized edge emittance produced by the diode is only {approx} 0.019 cm-rad. In the final-focus region, the authors have modeled the effect of ion emission from the target. The intense electric field of the beam at the 1-mm-diameter focal spot produces substantial ion velocities, and, if the space-charge-limited current density can be supplied, significant focal spot degradation may occur due to ion space-charge. Calculations for the existing Integrated Test Stand, which has a larger focal spot, show that the effect should be observable for H{sup +} and C{sup +} ion species. The effect is lessened if there is insufficient ion density on the target to supply the space-charge-limited current density, or if the ion charge-to-mass ratio is sufficiently small

Optical fibers with interferometric path length stability by controlled heating for transmission of optical signals and as components in frequency standards

We present a simple method to stabilize the optical path length of an optical fiber to an accuracy of about 1/100 of the laser wavelength. We study the dynamic response of the path length to modulation of an electrically conductive heater layer of the fiber. The path length is measured against the laser wavelength by use of the Pound-Drever-Hall method; negative feedback is applied via the heater. We apply the method in the context of a cryogenic resonator frequency standard.Comment: Expanded introduction and outlook. 9 pages, 5 figure

Modelling ponatinib resistance in tyrosine kinase inhibitor-naive and dasatinib resistant BCR-ABL1+ cell lines

TKI resistance remains a major impediment to successful treatment of CML. In this study, we investigated the emerging modes of ponatinib resistance in TKI-naïve and dasatinib resistant BCR-ABL1+ cell lines. To investigate potential resistance mechanisms, ponatinib resistance was generated in BCR-ABL1+ cell-lines by long-term exposure to increasing concentrations of ponatinib. Two cell lines with prior dasatinib resistance demonstrated BCR-ABL1 kinase domain (KD) mutation(s) upon exposure to ponatinib. In one of these cell lines the T315I mutation had emerged during dasatinib exposure. When further cultured with ponatinib, the T315I mutation level and BCR-ABL1 mRNA expression level were increased. In the other cell line, compound mutations G250E/E255K developed with ponatinib exposure. In contrast, the ponatinib resistant cell lines that had no prior exposure to other TKIs (TKI-naïve) did not develop BCR-ABL1 KD mutations. Rather, both of these cell lines demonstrated Bcr-Abl-independent resistance via Axl overexpression. Axl, a receptor tyrosine kinase, has previously been associated with imatinib and nilotinib resistance. Ponatinib sensitivity was restored following Axl inhibition or shRNA-mediated-knockdown of Axl, suggesting that Axl was the primary driver of resistance and a potential target for therapy in this setting.Liu Lu, Chung Hoow Kok, Verity Ann Saunders, Jueqiong Wang, Jennifer Anne McLean, Timothy Peter Hughes, and Deborah Lee Whit

Multi-lingual and multi-cultural information literacy; perspectives, models and good practice

Purpose This paper reviews current approaches to, and good practice, in information literacy development in multi-lingual and multi-cultural settings, with particular emphasis on provision for international students. Design/methodology/approach A selective and critical review of published literature is extended by evaluation of examples of multi-lingual information literacy tutorials and MOOCs. Findings Multi-lingual and multi-cultural information literacy are umbrella terms covering a variety of situations and issues. This provision is of increasing importance in an increasingly mobile and multi-cultural world. This article evaluates current approaches and good practice, focusing on issues of culture vis a vis language, the balance between individual and group needs, specific and generic information literacy instruction, and models for information literacy, pedagogy and culture. Recommendations for good practice and for further research are given, Originality/value This is one of very few articles critically reviewing how information literacy development is affected by linguistic and cultural factors