Impacts of climate change on non-native species

Anthropogenic changes to climate and extreme weather events have already led to the introduction of non-native species (NNS) to the North Atlantic. Regional climate models predict that there will be a continuation of the current trend of warming throughout the 21st century providing enhanced opportunities for NNS at each stage of the invasion process. Increasing evidence is now available to show that climate change has led to the northwards range expansion of a number of NNS in the UK and Ireland, such as the Asian club tunicate Styela clava and the Pacific oyster Crassostrea gigas. Providing definitive evidence though of the direct linkage between climate change and the spread of the majority of NNS is extremely challenging, due to other confounding factors, such as anthropogenic activity. Localised patterns of water movement and food supply may also be complicating the overall pattern of northwards range expansion, by preventing the expansion of some NNS, such as the slipper limpet Crepidula fornicata and the Chilean oyster Ostrea chilensis, from a particular region. A greater understanding of the other aspects of climate change and increased atmospheric CO2, such as increased rainfall, heat waves, frequency of storm events, and ocean acidification may aid in increasing the confidence that scientists have in predicting the long term influence of climate change on the introduction, spread and establishment of NNS.

Through the portal – improving the flow of information on non-native marine species in Great Britain.

Abstract: The UK Government funded, GB Non-Native Species Information Portal (GBNNSIP) collects and collates data on non-native species in Great Britain making information available online. Resources include a comprehensive register of non-native species and detailed fact sheets for a sub-set, significant to humans or the environment. Reporting of species records are linked to risk analyses, rapid responses and horizon scanning to support the early recognition of threats (Figure 12). The portal has improved flow of new and existing distributional data to the National Biodiversity Network (NBN) to generate distribution maps for the portal. The project is led by the Biological Records Centre and the Marine Biological Association is responsible for marine non-native species within this scheme. The INTERREG IV funded project Marinexus has included professional research and citizen science work, which has fed directly into the portal. The portal outputs and the work of Marinexus have a range of marine governance applications, including supporting work towards MSFD compliance.

Effect of self-generated magnetic fields on fast-electron beam divergence in solid targets

The collimating effect of self-generated magnetic fields on fast-electron transport in solid aluminium targets irradiated by ultra-intense, picosecond laser pulses is investigated in this study. As the target thickness is varied in the range of 25 mu m to 1.4 mm, the maximum energies of protons accelerated from the rear surface are measured to infer changes in the fast-electron density and therefore the divergence of the fast-electron beam transported through the target. Purely ballistic spreading of the fast-electrons would result in a much faster decrease in the maximum proton energy with increasing target thickness than that measured. This implies that some degree of 'global' magnetic pinching of the fast-electrons occurs, particularly for thick (>400 mu m) targets. Numerical simulations of electron transport are in good agreement with the experimental data and show that the pinching effect of the magnetic field in thin targets is significantly reduced due to disruption of the field growth by refluxing fast-electrons.

Spectral isometries on non-simple C*-algebras

We prove that unital surjective spectral isometries on certain non-simple unital C*-algebras are Jordan isomorphisms. Along the way, we establish several general facts in the setting of semisimple Banach algebras.

Monte Carlo studies of quantum and classical annealing on a double well

We present results for a variety of Monte Carlo annealing approaches, both classical and quantum, benchmarked against one another for the textbook optimization exercise of a simple one-dimensional double well. In classical (thermal) annealing, the dependence upon the move chosen in a Metropolis scheme is studied and correlated with the spectrum of the associated Markov transition matrix. In quantum annealing, the path integral Monte Carlo approach is found to yield nontrivial sampling difficulties associated with the tunneling between the two wells. The choice of fictitious quantum kinetic energy is also addressed. We find that a "relativistic" kinetic energy form, leading to a higher probability of long real-space jumps, can be considerably more effective than the standard nonrelativistic one.

Hybrid address spaces: A methodology for implementing scalable high-level programming models on non-coherent many-core architectures

This paper introduces hybrid address spaces as a fundamental design methodology for implementing scalable runtime systems on many-core architectures without hardware support for cache coherence. We use hybrid address spaces for an implementation of MapReduce, a programming model for large-scale data processing, and the implementation of a remote memory access (RMA) model. Both implementations are available on the Intel SCC and are portable to similar architectures. We present the design and implementation of HyMR, a MapReduce runtime system whereby different stages and the synchronization operations between them alternate between a distributed memory address space and a shared memory address space, to improve performance and scalability. We compare HyMR to a reference implementation and we find that HyMR improves performance by a factor of 1.71× over a set of representative MapReduce benchmarks. We also compare HyMR with Phoenix++, a state-of-art implementation for systems with hardware-managed cache coherence in terms of scalability and sustained to peak data processing bandwidth, where HyMR demon- strates improvements of a factor of 3.1× and 3.2× respectively. We further evaluate our hybrid remote memory access (HyRMA) programming model and assess its performance to be superior of that of message passing.