Influence of tides on melting and freezing beneath Filchner-Ronne Ice Shelf, Antarctica

An isopycnic coordinate ocean circulation model is applied to the ocean cavity beneath Filchner-Ronne Ice Shelf, investigating the role of tides on sub-ice shelf circulation and ice shelf basal mass balance. Including tidal forcing causes a significant intensification in the sub-ice shelf circulation, with an increase in melting (3-fold) and refreezing (6-fold); the net melt rate and seawater flux through the cavity approximately doubles. With tidal forcing, the spatial pattern and magnitude of basal melting and freezing generally match observations. The 0.22 m a(-1) net melt rate is close to satellite-derived estimates and at the lower end of oceanographic values. The Ice Shelf Water outflow mixes with shelf waters, forming a cold (<-1.9 degrees C), dense overflow (0.83 Sv) that spills down the continental slope. These results demonstrate that tidal forcing is fundamental to both ice shelf-ocean interactions and deep-water formation in the southern Weddell Sea. Citation: Makinson, K., P. R. Holland, A. Jenkins, K. W. Nicholls, and D. M. Holland (2011), Influence of tides on melting and freezing beneath Filchner-Ronne Ice Shelf, Antarctica, Geophys. Res. Lett., 38, L06601, doi: 10.1029/2010GL046462

Honeybee linguistics—a comparative analysis of the waggle dance among species of Apis

All honeybees use the waggle dance to recruit nestmates. Studies on the dance precision of Apis mellifera have shown that the dance is often imprecise. Two hypotheses have been put forward aimed at explaining this imprecision. The first argues that imprecision in the context of foraging is adaptive as it ensures that the dance advertises the same patch size irrespective of distance. The second argues that the bees are constrained in their ability to be more precise, especially when the source is nearby. Recent studies have found support for the latter hypothesis but not for the “tuned-error” hypothesis, as the adaptive hypothesis became known. Here we investigate intra-dance variation among Apis species. We analyse the dance precision of A. florea, A. dorsata, and A. mellifera in the context of foraging and swarming. A. mellifera performs forage dances in the dark, using gravity as point of reference, and in the light when dancing for nest sites, using the sun as point of reference. Both A. dorsata and A. florea are open-nesting species; they do not use a different point of reference depending on context. A. florea differs from both A. mellifera and A. dorsata in that it dances on a horizontal surface and does not use gravity but instead “points” directly toward the goal when indicating direction. Previous work on A. mellifera has suggested that differences in dance orientation and point of reference can affect dance precision. We find that all three species improve dance precision with increasing waggle phase duration, irrespective of differences in dance orientation, and point of reference. When dancing for sources nearby, dances are highly variable. When the distance increases, dance precision converges. The exception is dances performed by A. mellifera on swarms. Here, dance precision decreases as the distance increases. We also show that the size of the patch advertised increases with increasing distance, contrary to what is predicted under the tuned-error hypothesis

A comparative study on the felting propensity of animal fibers

The felting propensity of different animal fibers, particularly alpaca and wool, has been examined. The Aachen felting test method was employed. 1 g of each type of fiber was soaked in 50 ml of wetting solution and agitated in a dyeing machine to make felt balls. The diameter of each ball was measured in nine directions and the ball density was calculated in g/cm3; the higher the density value of the ball, the higher the feltability of the fibers. The effects of fiber diameter and fiber length on the felting propensity of these fibers were investigated. The results show that the alpaca fibers felt to a higher degree than wool fibers, and short and fine cashmere fibers have lower felting propensity than wool fibers at a similar diameter range. There is a higher tendency of felting for bleached and dyed alpaca fibers than for untreated fibers. Fiber length has a remarkable influence on the propensity of fiber felting. Cotton and nylon fibers were also tested for felting propensity to verify the mechanism responsible for the different fiber felting behavior. <br /

Harmonic radar tracking reveals that honeybee drones navigate between multiple aerial leks

Male honeybees (drones) are thought to congregate in large numbers in particular “drone congregation areas” to mate. We used harmonic radar to record the flight paths of individual drones and found that drones favored certain locations within the landscape which were stable over two years. Drones often visit multiple potential lekking sites within a single flight and take shared flight paths between them. Flights between such sites are relatively straight and begin as early as the drone's second flight, indicating familiarity with the sites acquired during initial learning flights. Arriving at congregation areas, drones display convoluted, looping flight patterns. We found a correlation between a drone's distance from the center of each area and its acceleration toward the center, a signature of collective behavior leading to congregation in these areas. Our study reveals the behavior of individual drones as they navigate between and within multiple aerial leks

Safety, the Preface Paradox and Possible Worlds Semantics

This paper contains an argument to the effect that possible worlds semantics renders semantic knowledge impossible, no matter what ontological interpretation is given to possible worlds. The essential contention made is that possible worlds semantic knowledge is unsafe and this is shown by a parallel with the preface paradox

A Review of Contemporary Methods for the Presentation of Scientific Uncertainty

Graphical methods for displaying uncertainty are often the most concise and informative way to communicate abstract concepts. Presentation methods currently in use for the display and interpretation of scientific uncertainty are reviewed. Numerous subjective and objective uncertainty display methods are presented, including qualitative assessments, node and arrow diagrams, standard statistical methods, box-and-whisker plots, robustness and opportunity functions, contribution indexes, probability density functions, cumulative distribution functions, and graphical likelihood functions.This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by the Health Physics Society and published by Lippincott Williams & Wilkins. The published article can be found at: http://journals.lww.com/health-physics/pages/default.aspx.Keywords: Reviews, Risk Communication, Risk Estimates, Public Informatio

Regulation of Thalamic and Cortical Network Synchrony by Scn8a.

Voltage-gated sodium channel (VGSC) mutations cause severe epilepsies marked by intermittent, pathological hypersynchronous brain states. Here we present two mechanisms that help to explain how mutations in one VGSC gene, Scn8a, contribute to two distinct seizure phenotypes: (1) hypoexcitation of cortical circuits leading to convulsive seizure resistance, and (2) hyperexcitation of thalamocortical circuits leading to non-convulsive absence epilepsy. We found that loss of Scn8a leads to altered RT cell intrinsic excitability and a failure in recurrent RT synaptic inhibition. We propose that these deficits cooperate to enhance thalamocortical network synchrony and generate pathological oscillations. To our knowledge, this finding is the first clear demonstration of a pathological state tied to disruption of the RT-RT synapse. Our observation that loss of a single gene in the thalamus of an adult wild-type animal is sufficient to cause spike-wave discharges is striking and represents an example of absence epilepsy of thalamic origin

Clean subglacial access:Prospects for future deep hot-water drilling

Accessing and sampling subglacial environments deep beneath the Antarctic Ice Sheet presents several challenges to existing drilling technologies. With over half of the ice sheet believed to be resting on a wet bed, drilling down to this environment must conform to international agreements on environmental stewardship and protection, making clean hot-water drilling the most viable option. Such a drill, and its water recovery system, must be capable of accessing significantly greater ice depths than previous hot-water drills, and remain fully operational after connecting with the basal hydrological system. The Subglacial Lake Ellsworth (SLE) project developed a comprehensive plan for deep (greater than 3000 m) subglacial lake research, involving the design and development of a clean deep-ice hot-water drill. However, during fieldwork in December 2012 drilling was halted after a succession of equipment issues culminated in a failure to link with a subsurface cavity and abandonment of the access holes. The lessons learned from this experience are presented here. Combining knowledge gained from these lessons with experience from other hot-water drilling programmes, and recent field testing, we describe the most viable technical options and operational procedures for future clean entry into SLE and other deep subglacial access targets.</p

Bumble bees strategically use ground level linear features in navigation

Extended ground level structures like roads or field edges can be important cues for navigating animals,seen for example in road-following pigeons. In a landscape devoid of skyline cues but with a rectangular grid of pathways and roads, we used harmonic radar to track free-flying bumble bees,Bombus terrestris. Individual bees consistently used ground level linear features for navigation in a wide range of behavioural contexts. Bee exploration flights, search behaviour and foraging routes were shaped by linear features, with bees frequently flying along and parallel to pathways and roads. Comparisons off light trajectories across these behavioural contexts show that individuals modulated their use of linear features strategically with respect to their individual goals and experience. Bees searching for a feeder used linear features to target their search, while foragers often followed pathways to return to their hive without overshooting. These findings on a major pollinator have important implications for the placements of bee colonies for agriculture and floral resources for conservation

Boolean Game with Prioritized Norms

In this paper we study boolean game with prioritized norms. Norms distinguish illegal strategies from legal strategies. Notions like legal strategy and legal Nash equilibrium are introduced. Our formal model is a combination of (weighted) boolean game and so called (prioritized) input/output logic. After formally presenting the model, we use examples to show that non-optimal Nash equilibrium can be avoided by making use of norms.We study various complexity issues related to legal strategy and legal Nash equilibrium