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In this paper, the applicability of heuristic methods for an automated and reactive optimization of network infrastructures in highly-dynamic communication networks is studied. With an increasing amount of (mobile) participants and at the same time significantly growing quality requirements in communication networks over the past years, optimization of communication infrastructures will become an inevitable challenge in providing a reliable and high-quality communication service. Mostly, changes in highly-dynamic networks, which may be planned or unplanned, happen swiftly, such that it is not possible to apply manual optimization. Thus, an automated and reactive optimization becomes necessary to address this problem. Two major issues arise from the optimization of highly-dynamic communication networks. First, the complexity of problems, which is either implied by the complex optimization problem or the number of different possibly concurrent goals subject to optimization. Second, the highly-dynamic optimization search space, where network topologies may change rapidly introducing severe challenges for the optimization process. Here, different evolutionary and greedy optimization heuristics for the optimal selection of monitors in communication networks are studied and compared. Monitor selection is a well-known, important, and complex (NP-hard) optimization problem, serving as a current and actual use case for the general concept of highly-dynamic communication network optimization. As the results show, two of three methods reliably provide solutions of sufficiently high quality in reasonable time, enabling the applicability of heuristic methods of optimization in highly-dynamic communication networks. Results of the experiments are obtained using state-of-the-art statistical methods for evaluation of (evolutionary) search heuristics on a set of 39 real-world and synthetic benchmark problem instances.

Past tracking studies of marine animals have primarily targeted adults, biasing our understanding of at-sea habitat use toward older life stages. Anthropogenic threats persist throughout the at-sea ranges of all life stages and it is therefore of interest to population ecologists and managers alike to understand spatiotemporal distributions and possible niche differentiation between age-classes. In albatrosses, particularly little is known about the juvenile life stage when fledglings depart the colonies and venture to sea with no prior experience or parental guidance. We compared the dispersal of 22 fledgling Black-footed Albatross Phoebastria nigripes between 2006 and 2008 using satellite telemetry and 16 adults between 2008 and 2009 using geolocaters from Midway Atoll National Wildlife Refuge, Northwest Hawaiian Islands. Following tag deployment, all fledglings spent several days within the calm atoll waters, then travelled northward until reaching 750-900km from the colony. At this point, fledgling distributions approached the productive North Pacific Transition Zone (NPTZ). Rather than reaching the high chlorophyll a densities on the leading edge of this zone, however, fledglings remained in areas of low productivity in the subtropical gyre. In contrast, adult albatrosses from the same breeding colony did not utilize the NPTZ at this time of year but rather ranged throughout the highly productive northern periphery of the Pacific Ocean Basin among the shelf regions off Japan and the Aleutian Islands. The dichotomy in habitat use between fledglings and adults from Midway Atoll results in complete spatial segregation between age-classes and suggests ontogenetic niche separation in this species. This research fills a large knowledge gap in at-sea habitat use during a little known yet critical life stage of albatrosses, and contributes to a more comprehensive understanding of differential mortality pressure between age-classes and overall conservation status for the vulnerable Black-footed Albatross.

A goal of seabird ecology is to relate the physiology, population dynamics, distribution and behaviour of seabirds with their biotic and abiotic environments. One of the most challenging aspects is to understand how seabirds interact with their environment when direct observations are not always possible or practical. In the present paper, we reviewed 218 published studies that examined associations between seabird distribution, behaviour and their environment, in order to assess current trends, weaknesses and the future directions of research. Based on the number of publications, it is evident that the field is growing rapidly and that methods for evaluating seabird distribution are becoming increasingly more sophisticated and are changing from Eulerian (grid-like) to Lagrangian (particle-like) data types. This has been accompanied by a reduction in the spatial and temporal scale of observation, where, in most cases, no behavioural information is inferred from Lagrangian data; instead they are often used as if they were Eulerian data. In parallel, environmental remote sensing is becoming more common; however, we did not record significant changes in the statistical approaches used to describe seabird distributions and used to link them with oceanographic variables. In particular, despite the spatially explicit nature of the data, spatial statistics have rarely been used. The vast majority of studies used environmental variables that described water masses (descriptive approach), whereas a few studies determined oceanographic features that enhance prey availability to seabirds (process-based approach). Future studies could enhance their ecological interpretation of seabird-environment interactions by making greater use of ad hoc statistical approaches that facilitate appropriate pattern detection (e.g. area-restricted searching pattern for birds, mesoscale patterns for environment). Furthermore, appropriate hypothesis testing and modelling that accounts for the spatially explicit, multiscale and multivariate nature of the interaction between seabirds and their habitats is recommended. Although quantitative methods currently exist (but are rarely used), further application could greatly improve our understanding of the processes linking seabird distribution to their environment.

A Pt(II) complex, bearing an oligo-ethyleneoxide pendant, is able to self-assemble in ultralong ribbons that display mechanochromism upon nanoscale mechanical stimuli, delivered through atomic force microscopy (AFM). Such observation paves the way to fine understanding and manipulation of the mechanochromic properties of such material at the nanoscale. AFM allows quantitative assessment of nanoscale mechanochromism as arising from static pressure (piezochromism) and from shear-based mechanical stimuli (tribochromism), and to compare them with bulk pressure-dependent luminescence observed with diamond-anvil cell (DAC) technique. Confocal spectral imaging reveals that mechanochromism only takes place within short distance from the localized mechanical stimulation, which allows to design high-density information writing with AFM nanolithography applied on individual self-assembled ribbons. Each ribbon hence serves as an individual microsystem for data storage. The orange luminescence of written information displays high contrast compared to cyan native luminescence; moreover, it can be selectively excited with visible light. In addition, ribbons show photochromism, i.e., the emission spectrum changes upon exposure to light, in a similar way as upon mechanical stress. Photochromism is here conveniently used to conceal and eventually erase information previously written with nanolithography by irradiation.