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In drag-based swimming, individual propulsors operating at low Reynolds numbers (where viscous forces dominate over inertial forces) must execute a spatially asymmetric stroke to produce net fluid displacement. Temporal asymmetry (that is, differing duration between the power vs. recovery stroke) does not affect the overall generated thrust in this time-reversible regime. Metachronal rowing, in which multiple appendages beat sequentially, is used by a wide variety of organisms from low to intermediate Reynolds numbers. At the upper end of this range, inertia becomes important, and increasing temporal asymmetry can be an effective way to increase thrust. However, the combined effects of spatial and temporal asymmetry are not fully understood in the context of metachronal rowing. To explore the role of spatiotemporal asymmetry in metachronal rowing, we combine laboratory experiments and reduced-order analytical modeling. We measure beat kinematics and generated flows in two species of lobate ctenophores across a range of body sizes, from 7 to 40 mm in length. We observe characteristically different flows in ctenophores of differing body size and Reynolds number, and a general decrease in spatial asymmetry and increase in temporal asymmetry with increasing Reynolds number. We also construct a one-dimensional mathematical model consisting of a row of oscillating flat plates whose flow-normal areas change with time, and use it to explore the propulsive forces generated across a range of Reynolds numbers and kinematic parameters. The model results show that while both types of asymmetry increase force production, they have different effects in different regions of the parameter space. These results may have strong biological implications, as temporal asymmetry can be actively controlled while spatial asymmetry is likely to be partially or entirely driven by passive fluid-structure interaction.

J. G. Ballard – sometime science fiction (sf) writer, catastrophist, literary provocateur, war writer, and diagnostician of late-twentieth and early-twenty-first century consumer society – launched...

China Mieville has been identified with the “new weird”, a loose-knit cabal of contemporary writers unsettling the generic borders between horror, sf and speculative fiction. Donna Haraway’s call for “tentacular thinking” seems aimed at smothering, feeling around and through, creeping out of the binaries and border policing of the Anthropocene/Capitalocene/Chthulucene, while Mieville’s novels thrill in different ways to the overrunning of borders—borders between ideas, beliefs, languages, people and species. Such border crossings abound in Mieville’s short fictions, too, and this chapter focusses on the short stories “Looking for Jake” (1998) “The Tain” (2002) and “Sacken” (2014), as ways into his weird and eerie border crossings.

The manipulation of host organisms by their parasites has captured the attention of ecologists, parasitologists, and the public. However, our knowledge of parasite behavior independent of a host is limited despite the far-reaching implications of parasite behavior. Parasite behaviors can help explain trematode community structure, the aggregation of parasites within host populations, and can potentially be harnessed in biocontrol measures. In this study, we used a simple choice chamber design to examine whether trematode parasites can detect the infection status of a potential host and avoid hosts infected with a competitively dominant species. Our results show that Schistosoma mansoni, a competitively subordinate species, can detect and avoid hosts infected with a competitively dominant parasite, Echinostoma caproni. However, E. caproni, despite showing a significant preference for snails infected with S. mansoni over uninfected snails, showed little ability to detect the infection status of the host or even the host's presence. We propose subordinate species may be under stronger selection to avoid dominant competitors whereas dominant competitors may be more strongly selected to find any suitable host, regardless of infection status. Previous research has focused on parasites distinguishing between ‘host’ and ‘non-host’, which does not fully capture the complexity of these interactions. However, the ability of subordinate parasites to determine the infection status of a host results in a consistent evolutionary advantage.

The nineteenth-century asylum was the scene of both terrible abuses and significant advancements in treatment and care. The essays in this collection look at the asylum from the perspective of the place itself - its architecture, funding and purpose - and at the experience of those who were sent there. © Taylor & Francis 2015. All rights reserved.

Free/Libre/Open Source Software (FLOSS) practitioners and developers are typically also users of their own systems: as a result, traditional software engineering (SE) processes (e.g., the requirements and design phases), take less time to articulate and negotiate among FLOSS developers. Design and requirements are kept more as informal knowledge, rather than formally described and assessed. This paper attempts to recover the SE concepts of software design and architectures from three FLOSS case studies, sharing the same application domain (i.e., Instant Messaging). Its first objective is to determine whether a common architecture emerges from the three systems, which can be used as shared knowledge for future applications. The second objective is to determine whether these architectures evolve or decay during the evolution of these systems. The results of this study are encouraging: albeit no explicit effort was done by FLOSS developers to define a high-level view of the architecture, a common shared architecture could be distilled for the Instant Messaging application domain. It was also found that, for two of the three systems, the architecture becomes better organised, and the components better specified, as long as the system evolves in time.