Rhythms of Locomotion Expressed by Limulus polyphemus, the American Horseshoe Crab: I. Synchronization by Artificial Tides

Limulus polyphemus, the American horseshoe crab, has an endogenous clock that drives circatidal rhythms of locomotor activity. In this study, we examined the ability of artificial tides to entrain the locomotor rhythms of Limulus in the laboratory. In experiments one and two, the activity of 16 individuals of L. polyphemus was monitored with activity boxes and “running wheels.” When the crabs were exposed to artificial tides created by changes in water depth, circatidal rhythms were observed in animals exposed to 12.4-h “tidal” cycles of either water depth changes (8 of 8 animals) or inundation (7 of 8 animals). In experiment three, an additional 8 animals were exposed to water depth changes under cyclic conditions of light and dark and then monitored for 10 days with no imposed artificial tides. Most animals (5) clearly synchronized their activity to the imposed artificial tidal cycles, and 3 of these animals showed clear evidence of entrainment after the artificial tides were terminated. Overall, these results demonstrate that the endogenous tidal clock that influences locomotion in Limulus can be entrained by imposed artificial tides. In the laboratory, these tidal cues override the influence of light/dark cycles. In their natural habitat, where both tidal and photoperiod inputs are typically always present, their activity rhythms are likely to be much more complex

Sisyphus effects in a microwave-excited flux-qubit resonator system

Sisyphus amplification, familiar from quantum optics, has recently been reported as a mechanism to explain the enhanced quality factor of a classical resonant (tank) circuit coupled to a superconducting flux qubit. Here we present data from a coupled system, comprising a quantum mechanical rf SQUID (flux qubit) reactively monitored by an ultrahigh quality factor noise driven rf resonator and excited by microwaves. The system exhibits enhancement of the tank-circuit resonance, bringing it significantly closer (within 1%) to the lasing limit, than previously reported results. 2010 The American Physical Society

Towards a theoretical framework on sensorial place brand identity

Purpose: This paper proposes a new framework on sensorial place brand identity. Design/Methodology/Approach: This conceptual paper draws from sensory marketing and brand identity theories to propose an integrative model to develop sensorial place brand identity. Findings: By relying on a broad spectrum of literature the study supports the notion that sensorial place brand identity is a bottom-up approach to branding that involves several enactment stakeholders and key influences as co-creators in the process of delivering sensory place branding messages based on a strong and unique place brand identity. This leads to the presentation of a provisional framework linking sensorial place identity, experiencescapes and multisensory place brand image. Originality/Value: This novel approach to place brand identity follows a holistic approach by considering several enactment stakeholders and key influencers as co-creators in the process of branding a place through the senses

A Spitzer Study of the Mass Loss Histories of Three Bipolar Pre-Planetary Nebulae

We present the results of far-infrared imaging of extended regions around three bipolar pre-planetary nebulae, AFGL 2688, OH 231.8+4.2, and IRAS 16342$-$3814, at 70 and 160 $\mu$m with the MIPS instrument on the Spitzer Space Telescope. After a careful subtraction of the point spread function of the central star from these images, we place constraints on the existence of extended shells and thus on the mass outflow rates as a function of radial distance from these stars. We find no apparent extended emission in AFGL 2688 and OH 231.8+4.2 beyond 100 arcseconds from the central source. In the case of AFGL 2688, this result is inconsistent with a previous report of two extended dust shells made on the basis of ISO observations. We derive an upper limit of $2.1\times10^{-7}$ M$_\odot$ yr$^{-1}$ and $1.0\times10^{-7}$ M$_\odot$ yr$^{-1}$ for the dust mass loss rate of AFGL 2688 and OH 231.8, respectively, at 200 arcseconds from each source. In contrast to these two sources, IRAS 16342$-$3814 does show extended emission at both wavelengths, which can be interpreted as a very large dust shell with a radius of $\sim$ 400 arcseconds and a thickness of $\sim$ 100 arcseconds, corresponding to 4 pc and 1 pc, respectively, at a distance of 2 kpc. However, this enhanced emission may also be galactic cirrus; better azimuthal coverage is necessary for confirmation of a shell. If the extended emission is a shell, it can be modeled as enhanced mass outflow at a dust mass outflow rate of $1.5\times10^{-6}$ M$_\odot$ yr$^{-1}$ superimposed on a steady outflow with a dust mass outflow rate of $1.5\times10^{-7}$ M$_\odot$ yr$^{-1}$. It is likely that this shell has swept up a substantial mass of interstellar gas during its expansion, so these estimates are upper limits to the stellar mass loss rate.Comment: 31 pages, 12 figures, accepted to A

Simulating Ability: Representing Skills in Games

Throughout the history of games, representing the abilities of the various agents acting on behalf of the players has been a central concern. With increasingly sophisticated games emerging, these simulations have become more realistic, but the underlying mechanisms are still, to a large extent, of an ad hoc nature. This paper proposes using a logistic model from psychometrics as a unified mechanism for task resolution in simulation-oriented games

Enhancing Academic Engagement: Providing Opportunities for Responding and Influencing Students to Choose to Respond

Although educators often provide opportunities for students to engage in active academic responding, in many situations, students either cannot or will not respond. In the current article, we analyze the reasons students fail to respond. Practical procedures educators can use to prevent can\u27t do problems are provided. Won\u27t do problems are conceptualized as choice behaviors. Both applied and theoretical research on choice behavior provides the basis for recommendations designed to enhance the probability of students choosing to engage in active accurate academic (AAA) responding. Such procedures can increase skill development and achievement while decreasing inappropriate behaviors that are incompatible with AAA responding. School psychologists may utilize this information during the initial stages of collaborative problem solving (e.g., consultation) to help conceptualize problems. This conceptualization may then guide the assessment and intervention processes

Millennial-scale variability of deep-water temperature and δ18Odwindicating deep-water source variations in the Northeast Atlantic, 0-34 cal. ka BP

Paired measurements of Mg/Ca and δ18Occ (calcite δ18O) in benthic foraminifera from a deep-sea core recovered on the Iberian Margin (MD99-2334K; 37°48′N, 10°10′W; 3,146 m) have been performed in parallel with planktonic δ18Occ analyses and counts of ice-rafted debris (IRD). The synchrony of temperature changes recorded in the Greenland ice cores and in North Atlantic planktonic δ18Occ allows the proxy records from MD99-2334K to be placed confidently on the GISP2 time-scale. This correlation is further corroborated by AMS 14C-dates. Benthic Mg/Ca measurements in MD99-2334K permit the reconstruction of past deep-water temperature (Tdw) changes since ∼34 cal. ka BP (calendar kiloyears before present). Using these Tdw estimates and parallel benthic δ18Occ measurements, a record of deep-water δ18O (δ18Odw) has been calculated. Results indicate greatly reduced Tdw in the deep Northeast Atlantic during the last glaciation until ∼15 cal. ka BP, when Tdw warmed abruptly to near-modern values in parallel with the onset of the Bølling-Allerød interstadial. Subsequently, Tdw reverted to cold glacial values between ∼13.4 and ∼11.4 cal. ka BP, in parallel with the Younger Dryas cold reversal and the H0 ice-rafting event. Similar millennial-scale Tdw changes also occurred during the last glaciation. Indeed, throughout the last ∼34 cal. ka, millennial δ18Odw and Tdw changes have remained well coupled and are linked with IRD pulses coincident with Heinrich events 3, 2, 1, and the Younger Dryas, when transitions to lower Tdw and δ18Odw conditions occurred. In general, millennial Tdw and δ18Odw variations recorded in MD99-2334K describe an alternation between colder, low-δ18Odw and warmer, high δ18Odw conditions, which suggests the changing local dominance of northern-sourced North Atlantic Deep Water (NADW) versus southern-sourced Antarctic Bottom Water (AABW). The observed similarity of the Tdw and GISP2 δ18Oice records would therefore suggest a common component of variability resulting from the coupling of NADW formation and Greenland climate. A link between Greenland stadials and the incursion of cold, low-δ18Odw AABW in the deep Northeast Atlantic is thus implied, which contributes to the relationship between Greenland climate and the millennial benthic δ18Occ signal since ∼34 cal. ka BP

Provenance and geochemistry of exotic clasts in conglomerates of the Oligocene Torehina Formation, Coromandel Peninsula, New Zealand

Non-marine pebble to cobble conglomerates of the lower Torehina Formation (Oligocene) crop out along western Coromandel Peninsula and overlie, with strong angular discordance, continental-margin metasedimentary rocks (Manaia Hill Group) of Mesozoic (Late Jurassic to ?Early Cretaceous) age. The conglomerates contain provenance information that identifies a pre-Oligocene depositional history obscured by the unconformable juxtaposition of these Tertiary and Mesozoic strata. Most clasts in the lower Torehina Formation are visually similar to local bedrock lithologies, including metamorphosed sandstones and argillites, but are kaolinitic and contain more detrital and authigenic chert, quartz, and potash feldspar. Local derivation of these clasts seems unlikely. By comparing geochemical ratios with those defined for continental margin sandstones, and well characterised New Zealand tectonic terranes, we interpret the majority of clasts in the lower Torehina Formation to have been derived from a dissected orogen, with mixtures of felsic and volcanogenic-derived sediment. The most likely sources are the Waipapa and Torlesse Terranes. The remaining 20–30% of the clasts in the lower Torehina Formation were originally friable, are coarse grained, and appear to be lithologically exotic relative to known metamorphosed sandstones in basement terrane sources on North Island. Some clasts contain coal laminae and particles, and all contain detrital kaolinite as lithic fragments and matrix. Such characteristics imply a non-marine to marginal-marine source containing sediment derived from strongly weathered granite or granodiorite. Mechanical fragility implies a likely proximal, easily erodible source. We propose that this group of clasts was derived from an Upper Cretaceous sedimentary cover, either part of a locally developed basin fill or part of a once regionally extensive cover on North Island. Either case defines a more widely distributed Cretaceous source than found today